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Diffstat (limited to 'contrib/gcc/loop.c')
| -rw-r--r-- | contrib/gcc/loop.c | 10846 |
1 files changed, 0 insertions, 10846 deletions
diff --git a/contrib/gcc/loop.c b/contrib/gcc/loop.c deleted file mode 100644 index fa74b8e..0000000 --- a/contrib/gcc/loop.c +++ /dev/null @@ -1,10846 +0,0 @@ -/* Perform various loop optimizations, including strength reduction. - Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997, - 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. - -This file is part of GCC. - -GCC is free software; you can redistribute it and/or modify it under -the terms of the GNU General Public License as published by the Free -Software Foundation; either version 2, or (at your option) any later -version. - -GCC is distributed in the hope that it will be useful, but WITHOUT ANY -WARRANTY; without even the implied warranty of MERCHANTABILITY or -FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -for more details. - -You should have received a copy of the GNU General Public License -along with GCC; see the file COPYING. If not, write to the Free -Software Foundation, 59 Temple Place - Suite 330, Boston, MA -02111-1307, USA. */ - -/* This is the loop optimization pass of the compiler. - It finds invariant computations within loops and moves them - to the beginning of the loop. Then it identifies basic and - general induction variables. - - Basic induction variables (BIVs) are a pseudo registers which are set within - a loop only by incrementing or decrementing its value. General induction - variables (GIVs) are pseudo registers with a value which is a linear function - of a basic induction variable. BIVs are recognized by `basic_induction_var'; - GIVs by `general_induction_var'. - - Once induction variables are identified, strength reduction is applied to the - general induction variables, and induction variable elimination is applied to - the basic induction variables. - - It also finds cases where - a register is set within the loop by zero-extending a narrower value - and changes these to zero the entire register once before the loop - and merely copy the low part within the loop. - - Most of the complexity is in heuristics to decide when it is worth - while to do these things. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include "tm.h" -#include "rtl.h" -#include "tm_p.h" -#include "function.h" -#include "expr.h" -#include "hard-reg-set.h" -#include "basic-block.h" -#include "insn-config.h" -#include "regs.h" -#include "recog.h" -#include "flags.h" -#include "real.h" -#include "loop.h" -#include "cselib.h" -#include "except.h" -#include "toplev.h" -#include "predict.h" -#include "insn-flags.h" -#include "optabs.h" -#include "cfgloop.h" -#include "ggc.h" - -/* Not really meaningful values, but at least something. */ -#ifndef SIMULTANEOUS_PREFETCHES -#define SIMULTANEOUS_PREFETCHES 3 -#endif -#ifndef PREFETCH_BLOCK -#define PREFETCH_BLOCK 32 -#endif -#ifndef HAVE_prefetch -#define HAVE_prefetch 0 -#define CODE_FOR_prefetch 0 -#define gen_prefetch(a,b,c) (abort(), NULL_RTX) -#endif - -/* Give up the prefetch optimizations once we exceed a given threshold. - It is unlikely that we would be able to optimize something in a loop - with so many detected prefetches. */ -#define MAX_PREFETCHES 100 -/* The number of prefetch blocks that are beneficial to fetch at once before - a loop with a known (and low) iteration count. */ -#define PREFETCH_BLOCKS_BEFORE_LOOP_MAX 6 -/* For very tiny loops it is not worthwhile to prefetch even before the loop, - since it is likely that the data are already in the cache. */ -#define PREFETCH_BLOCKS_BEFORE_LOOP_MIN 2 - -/* Parameterize some prefetch heuristics so they can be turned on and off - easily for performance testing on new architectures. These can be - defined in target-dependent files. */ - -/* Prefetch is worthwhile only when loads/stores are dense. */ -#ifndef PREFETCH_ONLY_DENSE_MEM -#define PREFETCH_ONLY_DENSE_MEM 1 -#endif - -/* Define what we mean by "dense" loads and stores; This value divided by 256 - is the minimum percentage of memory references that worth prefetching. */ -#ifndef PREFETCH_DENSE_MEM -#define PREFETCH_DENSE_MEM 220 -#endif - -/* Do not prefetch for a loop whose iteration count is known to be low. */ -#ifndef PREFETCH_NO_LOW_LOOPCNT -#define PREFETCH_NO_LOW_LOOPCNT 1 -#endif - -/* Define what we mean by a "low" iteration count. */ -#ifndef PREFETCH_LOW_LOOPCNT -#define PREFETCH_LOW_LOOPCNT 32 -#endif - -/* Do not prefetch for a loop that contains a function call; such a loop is - probably not an internal loop. */ -#ifndef PREFETCH_NO_CALL -#define PREFETCH_NO_CALL 1 -#endif - -/* Do not prefetch accesses with an extreme stride. */ -#ifndef PREFETCH_NO_EXTREME_STRIDE -#define PREFETCH_NO_EXTREME_STRIDE 1 -#endif - -/* Define what we mean by an "extreme" stride. */ -#ifndef PREFETCH_EXTREME_STRIDE -#define PREFETCH_EXTREME_STRIDE 4096 -#endif - -/* Define a limit to how far apart indices can be and still be merged - into a single prefetch. */ -#ifndef PREFETCH_EXTREME_DIFFERENCE -#define PREFETCH_EXTREME_DIFFERENCE 4096 -#endif - -/* Issue prefetch instructions before the loop to fetch data to be used - in the first few loop iterations. */ -#ifndef PREFETCH_BEFORE_LOOP -#define PREFETCH_BEFORE_LOOP 1 -#endif - -/* Do not handle reversed order prefetches (negative stride). */ -#ifndef PREFETCH_NO_REVERSE_ORDER -#define PREFETCH_NO_REVERSE_ORDER 1 -#endif - -/* Prefetch even if the GIV is in conditional code. */ -#ifndef PREFETCH_CONDITIONAL -#define PREFETCH_CONDITIONAL 1 -#endif - -#define LOOP_REG_LIFETIME(LOOP, REGNO) \ -((REGNO_LAST_LUID (REGNO) - REGNO_FIRST_LUID (REGNO))) - -#define LOOP_REG_GLOBAL_P(LOOP, REGNO) \ -((REGNO_LAST_LUID (REGNO) > INSN_LUID ((LOOP)->end) \ - || REGNO_FIRST_LUID (REGNO) < INSN_LUID ((LOOP)->start))) - -#define LOOP_REGNO_NREGS(REGNO, SET_DEST) \ -((REGNO) < FIRST_PSEUDO_REGISTER \ - ? (int) HARD_REGNO_NREGS ((REGNO), GET_MODE (SET_DEST)) : 1) - - -/* Vector mapping INSN_UIDs to luids. - The luids are like uids but increase monotonically always. - We use them to see whether a jump comes from outside a given loop. */ - -int *uid_luid; - -/* Indexed by INSN_UID, contains the ordinal giving the (innermost) loop - number the insn is contained in. */ - -struct loop **uid_loop; - -/* 1 + largest uid of any insn. */ - -int max_uid_for_loop; - -/* Number of loops detected in current function. Used as index to the - next few tables. */ - -static int max_loop_num; - -/* Bound on pseudo register number before loop optimization. - A pseudo has valid regscan info if its number is < max_reg_before_loop. */ -unsigned int max_reg_before_loop; - -/* The value to pass to the next call of reg_scan_update. */ -static int loop_max_reg; - -/* During the analysis of a loop, a chain of `struct movable's - is made to record all the movable insns found. - Then the entire chain can be scanned to decide which to move. */ - -struct movable -{ - rtx insn; /* A movable insn */ - rtx set_src; /* The expression this reg is set from. */ - rtx set_dest; /* The destination of this SET. */ - rtx dependencies; /* When INSN is libcall, this is an EXPR_LIST - of any registers used within the LIBCALL. */ - int consec; /* Number of consecutive following insns - that must be moved with this one. */ - unsigned int regno; /* The register it sets */ - short lifetime; /* lifetime of that register; - may be adjusted when matching movables - that load the same value are found. */ - short savings; /* Number of insns we can move for this reg, - including other movables that force this - or match this one. */ - ENUM_BITFIELD(machine_mode) savemode : 8; /* Nonzero means it is a mode for - a low part that we should avoid changing when - clearing the rest of the reg. */ - unsigned int cond : 1; /* 1 if only conditionally movable */ - unsigned int force : 1; /* 1 means MUST move this insn */ - unsigned int global : 1; /* 1 means reg is live outside this loop */ - /* If PARTIAL is 1, GLOBAL means something different: - that the reg is live outside the range from where it is set - to the following label. */ - unsigned int done : 1; /* 1 inhibits further processing of this */ - - unsigned int partial : 1; /* 1 means this reg is used for zero-extending. - In particular, moving it does not make it - invariant. */ - unsigned int move_insn : 1; /* 1 means that we call emit_move_insn to - load SRC, rather than copying INSN. */ - unsigned int move_insn_first:1;/* Same as above, if this is necessary for the - first insn of a consecutive sets group. */ - unsigned int is_equiv : 1; /* 1 means a REG_EQUIV is present on INSN. */ - unsigned int insert_temp : 1; /* 1 means we copy to a new pseudo and replace - the original insn with a copy from that - pseudo, rather than deleting it. */ - struct movable *match; /* First entry for same value */ - struct movable *forces; /* An insn that must be moved if this is */ - struct movable *next; -}; - - -FILE *loop_dump_stream; - -/* Forward declarations. */ - -static void invalidate_loops_containing_label (rtx); -static void find_and_verify_loops (rtx, struct loops *); -static void mark_loop_jump (rtx, struct loop *); -static void prescan_loop (struct loop *); -static int reg_in_basic_block_p (rtx, rtx); -static int consec_sets_invariant_p (const struct loop *, rtx, int, rtx); -static int labels_in_range_p (rtx, int); -static void count_one_set (struct loop_regs *, rtx, rtx, rtx *); -static void note_addr_stored (rtx, rtx, void *); -static void note_set_pseudo_multiple_uses (rtx, rtx, void *); -static int loop_reg_used_before_p (const struct loop *, rtx, rtx); -static rtx find_regs_nested (rtx, rtx); -static void scan_loop (struct loop*, int); -#if 0 -static void replace_call_address (rtx, rtx, rtx); -#endif -static rtx skip_consec_insns (rtx, int); -static int libcall_benefit (rtx); -static void ignore_some_movables (struct loop_movables *); -static void force_movables (struct loop_movables *); -static void combine_movables (struct loop_movables *, struct loop_regs *); -static int num_unmoved_movables (const struct loop *); -static int regs_match_p (rtx, rtx, struct loop_movables *); -static int rtx_equal_for_loop_p (rtx, rtx, struct loop_movables *, - struct loop_regs *); -static void add_label_notes (rtx, rtx); -static void move_movables (struct loop *loop, struct loop_movables *, int, - int); -static void loop_movables_add (struct loop_movables *, struct movable *); -static void loop_movables_free (struct loop_movables *); -static int count_nonfixed_reads (const struct loop *, rtx); -static void loop_bivs_find (struct loop *); -static void loop_bivs_init_find (struct loop *); -static void loop_bivs_check (struct loop *); -static void loop_givs_find (struct loop *); -static void loop_givs_check (struct loop *); -static int loop_biv_eliminable_p (struct loop *, struct iv_class *, int, int); -static int loop_giv_reduce_benefit (struct loop *, struct iv_class *, - struct induction *, rtx); -static void loop_givs_dead_check (struct loop *, struct iv_class *); -static void loop_givs_reduce (struct loop *, struct iv_class *); -static void loop_givs_rescan (struct loop *, struct iv_class *, rtx *); -static void loop_ivs_free (struct loop *); -static void strength_reduce (struct loop *, int); -static void find_single_use_in_loop (struct loop_regs *, rtx, rtx); -static int valid_initial_value_p (rtx, rtx, int, rtx); -static void find_mem_givs (const struct loop *, rtx, rtx, int, int); -static void record_biv (struct loop *, struct induction *, rtx, rtx, rtx, - rtx, rtx *, int, int); -static void check_final_value (const struct loop *, struct induction *); -static void loop_ivs_dump (const struct loop *, FILE *, int); -static void loop_iv_class_dump (const struct iv_class *, FILE *, int); -static void loop_biv_dump (const struct induction *, FILE *, int); -static void loop_giv_dump (const struct induction *, FILE *, int); -static void record_giv (const struct loop *, struct induction *, rtx, rtx, - rtx, rtx, rtx, rtx, int, enum g_types, int, int, - rtx *); -static void update_giv_derive (const struct loop *, rtx); -static HOST_WIDE_INT get_monotonic_increment (struct iv_class *); -static bool biased_biv_fits_mode_p (const struct loop *, struct iv_class *, - HOST_WIDE_INT, enum machine_mode, - unsigned HOST_WIDE_INT); -static bool biv_fits_mode_p (const struct loop *, struct iv_class *, - HOST_WIDE_INT, enum machine_mode, bool); -static bool extension_within_bounds_p (const struct loop *, struct iv_class *, - HOST_WIDE_INT, rtx); -static void check_ext_dependent_givs (const struct loop *, struct iv_class *); -static int basic_induction_var (const struct loop *, rtx, enum machine_mode, - rtx, rtx, rtx *, rtx *, rtx **); -static rtx simplify_giv_expr (const struct loop *, rtx, rtx *, int *); -static int general_induction_var (const struct loop *loop, rtx, rtx *, rtx *, - rtx *, rtx *, int, int *, enum machine_mode); -static int consec_sets_giv (const struct loop *, int, rtx, rtx, rtx, rtx *, - rtx *, rtx *, rtx *); -static int check_dbra_loop (struct loop *, int); -static rtx express_from_1 (rtx, rtx, rtx); -static rtx combine_givs_p (struct induction *, struct induction *); -static int cmp_combine_givs_stats (const void *, const void *); -static void combine_givs (struct loop_regs *, struct iv_class *); -static int product_cheap_p (rtx, rtx); -static int maybe_eliminate_biv (const struct loop *, struct iv_class *, int, - int, int); -static int maybe_eliminate_biv_1 (const struct loop *, rtx, rtx, - struct iv_class *, int, basic_block, rtx); -static int last_use_this_basic_block (rtx, rtx); -static void record_initial (rtx, rtx, void *); -static void update_reg_last_use (rtx, rtx); -static rtx next_insn_in_loop (const struct loop *, rtx); -static void loop_regs_scan (const struct loop *, int); -static int count_insns_in_loop (const struct loop *); -static int find_mem_in_note_1 (rtx *, void *); -static rtx find_mem_in_note (rtx); -static void load_mems (const struct loop *); -static int insert_loop_mem (rtx *, void *); -static int replace_loop_mem (rtx *, void *); -static void replace_loop_mems (rtx, rtx, rtx, int); -static int replace_loop_reg (rtx *, void *); -static void replace_loop_regs (rtx insn, rtx, rtx); -static void note_reg_stored (rtx, rtx, void *); -static void try_copy_prop (const struct loop *, rtx, unsigned int); -static void try_swap_copy_prop (const struct loop *, rtx, unsigned int); -static rtx check_insn_for_givs (struct loop *, rtx, int, int); -static rtx check_insn_for_bivs (struct loop *, rtx, int, int); -static rtx gen_add_mult (rtx, rtx, rtx, rtx); -static void loop_regs_update (const struct loop *, rtx); -static int iv_add_mult_cost (rtx, rtx, rtx, rtx); - -static rtx loop_insn_emit_after (const struct loop *, basic_block, rtx, rtx); -static rtx loop_call_insn_emit_before (const struct loop *, basic_block, - rtx, rtx); -static rtx loop_call_insn_hoist (const struct loop *, rtx); -static rtx loop_insn_sink_or_swim (const struct loop *, rtx); - -static void loop_dump_aux (const struct loop *, FILE *, int); -static void loop_delete_insns (rtx, rtx); -static HOST_WIDE_INT remove_constant_addition (rtx *); -static rtx gen_load_of_final_value (rtx, rtx); -void debug_ivs (const struct loop *); -void debug_iv_class (const struct iv_class *); -void debug_biv (const struct induction *); -void debug_giv (const struct induction *); -void debug_loop (const struct loop *); -void debug_loops (const struct loops *); - -typedef struct loop_replace_args -{ - rtx match; - rtx replacement; - rtx insn; -} loop_replace_args; - -/* Nonzero iff INSN is between START and END, inclusive. */ -#define INSN_IN_RANGE_P(INSN, START, END) \ - (INSN_UID (INSN) < max_uid_for_loop \ - && INSN_LUID (INSN) >= INSN_LUID (START) \ - && INSN_LUID (INSN) <= INSN_LUID (END)) - -/* Indirect_jump_in_function is computed once per function. */ -static int indirect_jump_in_function; -static int indirect_jump_in_function_p (rtx); - -static int compute_luids (rtx, rtx, int); - -static int biv_elimination_giv_has_0_offset (struct induction *, - struct induction *, rtx); - -/* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to - copy the value of the strength reduced giv to its original register. */ -static int copy_cost; - -/* Cost of using a register, to normalize the benefits of a giv. */ -static int reg_address_cost; - -void -init_loop (void) -{ - rtx reg = gen_rtx_REG (word_mode, LAST_VIRTUAL_REGISTER + 1); - - reg_address_cost = address_cost (reg, SImode); - - copy_cost = COSTS_N_INSNS (1); -} - -/* Compute the mapping from uids to luids. - LUIDs are numbers assigned to insns, like uids, - except that luids increase monotonically through the code. - Start at insn START and stop just before END. Assign LUIDs - starting with PREV_LUID + 1. Return the last assigned LUID + 1. */ -static int -compute_luids (rtx start, rtx end, int prev_luid) -{ - int i; - rtx insn; - - for (insn = start, i = prev_luid; insn != end; insn = NEXT_INSN (insn)) - { - if (INSN_UID (insn) >= max_uid_for_loop) - continue; - /* Don't assign luids to line-number NOTEs, so that the distance in - luids between two insns is not affected by -g. */ - if (GET_CODE (insn) != NOTE - || NOTE_LINE_NUMBER (insn) <= 0) - uid_luid[INSN_UID (insn)] = ++i; - else - /* Give a line number note the same luid as preceding insn. */ - uid_luid[INSN_UID (insn)] = i; - } - return i + 1; -} - -/* Entry point of this file. Perform loop optimization - on the current function. F is the first insn of the function - and DUMPFILE is a stream for output of a trace of actions taken - (or 0 if none should be output). */ - -void -loop_optimize (rtx f, FILE *dumpfile, int flags) -{ - rtx insn; - int i; - struct loops loops_data; - struct loops *loops = &loops_data; - struct loop_info *loops_info; - - loop_dump_stream = dumpfile; - - init_recog_no_volatile (); - - max_reg_before_loop = max_reg_num (); - loop_max_reg = max_reg_before_loop; - - regs_may_share = 0; - - /* Count the number of loops. */ - - max_loop_num = 0; - for (insn = f; insn; insn = NEXT_INSN (insn)) - { - if (GET_CODE (insn) == NOTE - && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) - max_loop_num++; - } - - /* Don't waste time if no loops. */ - if (max_loop_num == 0) - return; - - loops->num = max_loop_num; - - /* Get size to use for tables indexed by uids. - Leave some space for labels allocated by find_and_verify_loops. */ - max_uid_for_loop = get_max_uid () + 1 + max_loop_num * 32; - - uid_luid = xcalloc (max_uid_for_loop, sizeof (int)); - uid_loop = xcalloc (max_uid_for_loop, sizeof (struct loop *)); - - /* Allocate storage for array of loops. */ - loops->array = xcalloc (loops->num, sizeof (struct loop)); - - /* Find and process each loop. - First, find them, and record them in order of their beginnings. */ - find_and_verify_loops (f, loops); - - /* Allocate and initialize auxiliary loop information. */ - loops_info = xcalloc (loops->num, sizeof (struct loop_info)); - for (i = 0; i < (int) loops->num; i++) - loops->array[i].aux = loops_info + i; - - /* Now find all register lifetimes. This must be done after - find_and_verify_loops, because it might reorder the insns in the - function. */ - reg_scan (f, max_reg_before_loop, 1); - - /* This must occur after reg_scan so that registers created by gcse - will have entries in the register tables. - - We could have added a call to reg_scan after gcse_main in toplev.c, - but moving this call to init_alias_analysis is more efficient. */ - init_alias_analysis (); - - /* See if we went too far. Note that get_max_uid already returns - one more that the maximum uid of all insn. */ - if (get_max_uid () > max_uid_for_loop) - abort (); - /* Now reset it to the actual size we need. See above. */ - max_uid_for_loop = get_max_uid (); - - /* find_and_verify_loops has already called compute_luids, but it - might have rearranged code afterwards, so we need to recompute - the luids now. */ - compute_luids (f, NULL_RTX, 0); - - /* Don't leave gaps in uid_luid for insns that have been - deleted. It is possible that the first or last insn - using some register has been deleted by cross-jumping. - Make sure that uid_luid for that former insn's uid - points to the general area where that insn used to be. */ - for (i = 0; i < max_uid_for_loop; i++) - { - uid_luid[0] = uid_luid[i]; - if (uid_luid[0] != 0) - break; - } - for (i = 0; i < max_uid_for_loop; i++) - if (uid_luid[i] == 0) - uid_luid[i] = uid_luid[i - 1]; - - /* Determine if the function has indirect jump. On some systems - this prevents low overhead loop instructions from being used. */ - indirect_jump_in_function = indirect_jump_in_function_p (f); - - /* Now scan the loops, last ones first, since this means inner ones are done - before outer ones. */ - for (i = max_loop_num - 1; i >= 0; i--) - { - struct loop *loop = &loops->array[i]; - - if (! loop->invalid && loop->end) - { - scan_loop (loop, flags); - ggc_collect (); - } - } - - end_alias_analysis (); - - /* Clean up. */ - for (i = 0; i < (int) loops->num; i++) - free (loops_info[i].mems); - - free (uid_luid); - free (uid_loop); - free (loops_info); - free (loops->array); -} - -/* Returns the next insn, in execution order, after INSN. START and - END are the NOTE_INSN_LOOP_BEG and NOTE_INSN_LOOP_END for the loop, - respectively. LOOP->TOP, if non-NULL, is the top of the loop in the - insn-stream; it is used with loops that are entered near the - bottom. */ - -static rtx -next_insn_in_loop (const struct loop *loop, rtx insn) -{ - insn = NEXT_INSN (insn); - - if (insn == loop->end) - { - if (loop->top) - /* Go to the top of the loop, and continue there. */ - insn = loop->top; - else - /* We're done. */ - insn = NULL_RTX; - } - - if (insn == loop->scan_start) - /* We're done. */ - insn = NULL_RTX; - - return insn; -} - -/* Find any register references hidden inside X and add them to - the dependency list DEPS. This is used to look inside CLOBBER (MEM - when checking whether a PARALLEL can be pulled out of a loop. */ - -static rtx -find_regs_nested (rtx deps, rtx x) -{ - enum rtx_code code = GET_CODE (x); - if (code == REG) - deps = gen_rtx_EXPR_LIST (VOIDmode, x, deps); - else - { - const char *fmt = GET_RTX_FORMAT (code); - int i, j; - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - deps = find_regs_nested (deps, XEXP (x, i)); - else if (fmt[i] == 'E') - for (j = 0; j < XVECLEN (x, i); j++) - deps = find_regs_nested (deps, XVECEXP (x, i, j)); - } - } - return deps; -} - -/* Optimize one loop described by LOOP. */ - -/* ??? Could also move memory writes out of loops if the destination address - is invariant, the source is invariant, the memory write is not volatile, - and if we can prove that no read inside the loop can read this address - before the write occurs. If there is a read of this address after the - write, then we can also mark the memory read as invariant. */ - -static void -scan_loop (struct loop *loop, int flags) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_regs *regs = LOOP_REGS (loop); - int i; - rtx loop_start = loop->start; - rtx loop_end = loop->end; - rtx p; - /* 1 if we are scanning insns that could be executed zero times. */ - int maybe_never = 0; - /* 1 if we are scanning insns that might never be executed - due to a subroutine call which might exit before they are reached. */ - int call_passed = 0; - /* Number of insns in the loop. */ - int insn_count; - int tem; - rtx temp, update_start, update_end; - /* The SET from an insn, if it is the only SET in the insn. */ - rtx set, set1; - /* Chain describing insns movable in current loop. */ - struct loop_movables *movables = LOOP_MOVABLES (loop); - /* Ratio of extra register life span we can justify - for saving an instruction. More if loop doesn't call subroutines - since in that case saving an insn makes more difference - and more registers are available. */ - int threshold; - /* Nonzero if we are scanning instructions in a sub-loop. */ - int loop_depth = 0; - int in_libcall; - - loop->top = 0; - - movables->head = 0; - movables->last = 0; - - /* Determine whether this loop starts with a jump down to a test at - the end. This will occur for a small number of loops with a test - that is too complex to duplicate in front of the loop. - - We search for the first insn or label in the loop, skipping NOTEs. - However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG - (because we might have a loop executed only once that contains a - loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END - (in case we have a degenerate loop). - - Note that if we mistakenly think that a loop is entered at the top - when, in fact, it is entered at the exit test, the only effect will be - slightly poorer optimization. Making the opposite error can generate - incorrect code. Since very few loops now start with a jump to the - exit test, the code here to detect that case is very conservative. */ - - for (p = NEXT_INSN (loop_start); - p != loop_end - && GET_CODE (p) != CODE_LABEL && ! INSN_P (p) - && (GET_CODE (p) != NOTE - || (NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_BEG - && NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_END)); - p = NEXT_INSN (p)) - ; - - loop->scan_start = p; - - /* If loop end is the end of the current function, then emit a - NOTE_INSN_DELETED after loop_end and set loop->sink to the dummy - note insn. This is the position we use when sinking insns out of - the loop. */ - if (NEXT_INSN (loop->end) != 0) - loop->sink = NEXT_INSN (loop->end); - else - loop->sink = emit_note_after (NOTE_INSN_DELETED, loop->end); - - /* Set up variables describing this loop. */ - prescan_loop (loop); - threshold = (loop_info->has_call ? 1 : 2) * (1 + n_non_fixed_regs); - - /* If loop has a jump before the first label, - the true entry is the target of that jump. - Start scan from there. - But record in LOOP->TOP the place where the end-test jumps - back to so we can scan that after the end of the loop. */ - if (GET_CODE (p) == JUMP_INSN - /* Loop entry must be unconditional jump (and not a RETURN) */ - && any_uncondjump_p (p) - && JUMP_LABEL (p) != 0 - /* Check to see whether the jump actually - jumps out of the loop (meaning it's no loop). - This case can happen for things like - do {..} while (0). If this label was generated previously - by loop, we can't tell anything about it and have to reject - the loop. */ - && INSN_IN_RANGE_P (JUMP_LABEL (p), loop_start, loop_end)) - { - loop->top = next_label (loop->scan_start); - loop->scan_start = JUMP_LABEL (p); - } - - /* If LOOP->SCAN_START was an insn created by loop, we don't know its luid - as required by loop_reg_used_before_p. So skip such loops. (This - test may never be true, but it's best to play it safe.) - - Also, skip loops where we do not start scanning at a label. This - test also rejects loops starting with a JUMP_INSN that failed the - test above. */ - - if (INSN_UID (loop->scan_start) >= max_uid_for_loop - || GET_CODE (loop->scan_start) != CODE_LABEL) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "\nLoop from %d to %d is phony.\n\n", - INSN_UID (loop_start), INSN_UID (loop_end)); - return; - } - - /* Allocate extra space for REGs that might be created by load_mems. - We allocate a little extra slop as well, in the hopes that we - won't have to reallocate the regs array. */ - loop_regs_scan (loop, loop_info->mems_idx + 16); - insn_count = count_insns_in_loop (loop); - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "\nLoop from %d to %d: %d real insns.\n", - INSN_UID (loop_start), INSN_UID (loop_end), insn_count); - if (loop->cont) - fprintf (loop_dump_stream, "Continue at insn %d.\n", - INSN_UID (loop->cont)); - } - - /* Scan through the loop finding insns that are safe to move. - Set REGS->ARRAY[I].SET_IN_LOOP negative for the reg I being set, so that - this reg will be considered invariant for subsequent insns. - We consider whether subsequent insns use the reg - in deciding whether it is worth actually moving. - - MAYBE_NEVER is nonzero if we have passed a conditional jump insn - and therefore it is possible that the insns we are scanning - would never be executed. At such times, we must make sure - that it is safe to execute the insn once instead of zero times. - When MAYBE_NEVER is 0, all insns will be executed at least once - so that is not a problem. */ - - for (in_libcall = 0, p = next_insn_in_loop (loop, loop->scan_start); - p != NULL_RTX; - p = next_insn_in_loop (loop, p)) - { - if (in_libcall && INSN_P (p) && find_reg_note (p, REG_RETVAL, NULL_RTX)) - in_libcall--; - if (GET_CODE (p) == INSN) - { - /* Do not scan past an optimization barrier. */ - if (GET_CODE (PATTERN (p)) == ASM_INPUT) - break; - temp = find_reg_note (p, REG_LIBCALL, NULL_RTX); - if (temp) - in_libcall++; - if (! in_libcall - && (set = single_set (p)) - && GET_CODE (SET_DEST (set)) == REG -#ifdef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED - && SET_DEST (set) != pic_offset_table_rtx -#endif - && ! regs->array[REGNO (SET_DEST (set))].may_not_optimize) - { - int tem1 = 0; - int tem2 = 0; - int move_insn = 0; - int insert_temp = 0; - rtx src = SET_SRC (set); - rtx dependencies = 0; - - /* Figure out what to use as a source of this insn. If a - REG_EQUIV note is given or if a REG_EQUAL note with a - constant operand is specified, use it as the source and - mark that we should move this insn by calling - emit_move_insn rather that duplicating the insn. - - Otherwise, only use the REG_EQUAL contents if a REG_RETVAL - note is present. */ - temp = find_reg_note (p, REG_EQUIV, NULL_RTX); - if (temp) - src = XEXP (temp, 0), move_insn = 1; - else - { - temp = find_reg_note (p, REG_EQUAL, NULL_RTX); - if (temp && CONSTANT_P (XEXP (temp, 0))) - src = XEXP (temp, 0), move_insn = 1; - if (temp && find_reg_note (p, REG_RETVAL, NULL_RTX)) - { - src = XEXP (temp, 0); - /* A libcall block can use regs that don't appear in - the equivalent expression. To move the libcall, - we must move those regs too. */ - dependencies = libcall_other_reg (p, src); - } - } - - /* For parallels, add any possible uses to the dependencies, as - we can't move the insn without resolving them first. - MEMs inside CLOBBERs may also reference registers; these - count as implicit uses. */ - if (GET_CODE (PATTERN (p)) == PARALLEL) - { - for (i = 0; i < XVECLEN (PATTERN (p), 0); i++) - { - rtx x = XVECEXP (PATTERN (p), 0, i); - if (GET_CODE (x) == USE) - dependencies - = gen_rtx_EXPR_LIST (VOIDmode, XEXP (x, 0), - dependencies); - else if (GET_CODE (x) == CLOBBER - && GET_CODE (XEXP (x, 0)) == MEM) - dependencies = find_regs_nested (dependencies, - XEXP (XEXP (x, 0), 0)); - } - } - - if (/* The register is used in basic blocks other - than the one where it is set (meaning that - something after this point in the loop might - depend on its value before the set). */ - ! reg_in_basic_block_p (p, SET_DEST (set)) - /* And the set is not guaranteed to be executed once - the loop starts, or the value before the set is - needed before the set occurs... - - ??? Note we have quadratic behavior here, mitigated - by the fact that the previous test will often fail for - large loops. Rather than re-scanning the entire loop - each time for register usage, we should build tables - of the register usage and use them here instead. */ - && (maybe_never - || loop_reg_used_before_p (loop, set, p))) - /* It is unsafe to move the set. However, it may be OK to - move the source into a new pseudo, and substitute a - reg-to-reg copy for the original insn. - - This code used to consider it OK to move a set of a variable - which was not created by the user and not used in an exit - test. - That behavior is incorrect and was removed. */ - insert_temp = 1; - - /* Don't try to optimize a MODE_CC set with a constant - source. It probably will be combined with a conditional - jump. */ - if (GET_MODE_CLASS (GET_MODE (SET_DEST (set))) == MODE_CC - && CONSTANT_P (src)) - ; - /* Don't try to optimize a register that was made - by loop-optimization for an inner loop. - We don't know its life-span, so we can't compute - the benefit. */ - else if (REGNO (SET_DEST (set)) >= max_reg_before_loop) - ; - /* Don't move the source and add a reg-to-reg copy: - - with -Os (this certainly increases size), - - if the mode doesn't support copy operations (obviously), - - if the source is already a reg (the motion will gain nothing), - - if the source is a legitimate constant (likewise). */ - else if (insert_temp - && (optimize_size - || ! can_copy_p (GET_MODE (SET_SRC (set))) - || GET_CODE (SET_SRC (set)) == REG - || (CONSTANT_P (SET_SRC (set)) - && LEGITIMATE_CONSTANT_P (SET_SRC (set))))) - ; - else if ((tem = loop_invariant_p (loop, src)) - && (dependencies == 0 - || (tem2 - = loop_invariant_p (loop, dependencies)) != 0) - && (regs->array[REGNO (SET_DEST (set))].set_in_loop == 1 - || (tem1 - = consec_sets_invariant_p - (loop, SET_DEST (set), - regs->array[REGNO (SET_DEST (set))].set_in_loop, - p))) - /* If the insn can cause a trap (such as divide by zero), - can't move it unless it's guaranteed to be executed - once loop is entered. Even a function call might - prevent the trap insn from being reached - (since it might exit!) */ - && ! ((maybe_never || call_passed) - && may_trap_p (src))) - { - struct movable *m; - int regno = REGNO (SET_DEST (set)); - - /* A potential lossage is where we have a case where two insns - can be combined as long as they are both in the loop, but - we move one of them outside the loop. For large loops, - this can lose. The most common case of this is the address - of a function being called. - - Therefore, if this register is marked as being used - exactly once if we are in a loop with calls - (a "large loop"), see if we can replace the usage of - this register with the source of this SET. If we can, - delete this insn. - - Don't do this if P has a REG_RETVAL note or if we have - SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */ - - if (loop_info->has_call - && regs->array[regno].single_usage != 0 - && regs->array[regno].single_usage != const0_rtx - && REGNO_FIRST_UID (regno) == INSN_UID (p) - && (REGNO_LAST_UID (regno) - == INSN_UID (regs->array[regno].single_usage)) - && regs->array[regno].set_in_loop == 1 - && GET_CODE (SET_SRC (set)) != ASM_OPERANDS - && ! side_effects_p (SET_SRC (set)) - && ! find_reg_note (p, REG_RETVAL, NULL_RTX) - && (! SMALL_REGISTER_CLASSES - || (! (GET_CODE (SET_SRC (set)) == REG - && (REGNO (SET_SRC (set)) - < FIRST_PSEUDO_REGISTER)))) - && regno >= FIRST_PSEUDO_REGISTER - /* This test is not redundant; SET_SRC (set) might be - a call-clobbered register and the life of REGNO - might span a call. */ - && ! modified_between_p (SET_SRC (set), p, - regs->array[regno].single_usage) - && no_labels_between_p (p, - regs->array[regno].single_usage) - && validate_replace_rtx (SET_DEST (set), SET_SRC (set), - regs->array[regno].single_usage)) - { - /* Replace any usage in a REG_EQUAL note. Must copy - the new source, so that we don't get rtx sharing - between the SET_SOURCE and REG_NOTES of insn p. */ - REG_NOTES (regs->array[regno].single_usage) - = (replace_rtx - (REG_NOTES (regs->array[regno].single_usage), - SET_DEST (set), copy_rtx (SET_SRC (set)))); - - delete_insn (p); - for (i = 0; i < LOOP_REGNO_NREGS (regno, SET_DEST (set)); - i++) - regs->array[regno+i].set_in_loop = 0; - continue; - } - - m = xmalloc (sizeof (struct movable)); - m->next = 0; - m->insn = p; - m->set_src = src; - m->dependencies = dependencies; - m->set_dest = SET_DEST (set); - m->force = 0; - m->consec - = regs->array[REGNO (SET_DEST (set))].set_in_loop - 1; - m->done = 0; - m->forces = 0; - m->partial = 0; - m->move_insn = move_insn; - m->move_insn_first = 0; - m->insert_temp = insert_temp; - m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); - m->savemode = VOIDmode; - m->regno = regno; - /* Set M->cond if either loop_invariant_p - or consec_sets_invariant_p returned 2 - (only conditionally invariant). */ - m->cond = ((tem | tem1 | tem2) > 1); - m->global = LOOP_REG_GLOBAL_P (loop, regno); - m->match = 0; - m->lifetime = LOOP_REG_LIFETIME (loop, regno); - m->savings = regs->array[regno].n_times_set; - if (find_reg_note (p, REG_RETVAL, NULL_RTX)) - m->savings += libcall_benefit (p); - for (i = 0; i < LOOP_REGNO_NREGS (regno, SET_DEST (set)); i++) - regs->array[regno+i].set_in_loop = move_insn ? -2 : -1; - /* Add M to the end of the chain MOVABLES. */ - loop_movables_add (movables, m); - - if (m->consec > 0) - { - /* It is possible for the first instruction to have a - REG_EQUAL note but a non-invariant SET_SRC, so we must - remember the status of the first instruction in case - the last instruction doesn't have a REG_EQUAL note. */ - m->move_insn_first = m->move_insn; - - /* Skip this insn, not checking REG_LIBCALL notes. */ - p = next_nonnote_insn (p); - /* Skip the consecutive insns, if there are any. */ - p = skip_consec_insns (p, m->consec); - /* Back up to the last insn of the consecutive group. */ - p = prev_nonnote_insn (p); - - /* We must now reset m->move_insn, m->is_equiv, and - possibly m->set_src to correspond to the effects of - all the insns. */ - temp = find_reg_note (p, REG_EQUIV, NULL_RTX); - if (temp) - m->set_src = XEXP (temp, 0), m->move_insn = 1; - else - { - temp = find_reg_note (p, REG_EQUAL, NULL_RTX); - if (temp && CONSTANT_P (XEXP (temp, 0))) - m->set_src = XEXP (temp, 0), m->move_insn = 1; - else - m->move_insn = 0; - - } - m->is_equiv - = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); - } - } - /* If this register is always set within a STRICT_LOW_PART - or set to zero, then its high bytes are constant. - So clear them outside the loop and within the loop - just load the low bytes. - We must check that the machine has an instruction to do so. - Also, if the value loaded into the register - depends on the same register, this cannot be done. */ - else if (SET_SRC (set) == const0_rtx - && GET_CODE (NEXT_INSN (p)) == INSN - && (set1 = single_set (NEXT_INSN (p))) - && GET_CODE (set1) == SET - && (GET_CODE (SET_DEST (set1)) == STRICT_LOW_PART) - && (GET_CODE (XEXP (SET_DEST (set1), 0)) == SUBREG) - && (SUBREG_REG (XEXP (SET_DEST (set1), 0)) - == SET_DEST (set)) - && !reg_mentioned_p (SET_DEST (set), SET_SRC (set1))) - { - int regno = REGNO (SET_DEST (set)); - if (regs->array[regno].set_in_loop == 2) - { - struct movable *m; - m = xmalloc (sizeof (struct movable)); - m->next = 0; - m->insn = p; - m->set_dest = SET_DEST (set); - m->dependencies = 0; - m->force = 0; - m->consec = 0; - m->done = 0; - m->forces = 0; - m->move_insn = 0; - m->move_insn_first = 0; - m->insert_temp = insert_temp; - m->partial = 1; - /* If the insn may not be executed on some cycles, - we can't clear the whole reg; clear just high part. - Not even if the reg is used only within this loop. - Consider this: - while (1) - while (s != t) { - if (foo ()) x = *s; - use (x); - } - Clearing x before the inner loop could clobber a value - being saved from the last time around the outer loop. - However, if the reg is not used outside this loop - and all uses of the register are in the same - basic block as the store, there is no problem. - - If this insn was made by loop, we don't know its - INSN_LUID and hence must make a conservative - assumption. */ - m->global = (INSN_UID (p) >= max_uid_for_loop - || LOOP_REG_GLOBAL_P (loop, regno) - || (labels_in_range_p - (p, REGNO_FIRST_LUID (regno)))); - if (maybe_never && m->global) - m->savemode = GET_MODE (SET_SRC (set1)); - else - m->savemode = VOIDmode; - m->regno = regno; - m->cond = 0; - m->match = 0; - m->lifetime = LOOP_REG_LIFETIME (loop, regno); - m->savings = 1; - for (i = 0; - i < LOOP_REGNO_NREGS (regno, SET_DEST (set)); - i++) - regs->array[regno+i].set_in_loop = -1; - /* Add M to the end of the chain MOVABLES. */ - loop_movables_add (movables, m); - } - } - } - } - /* Past a call insn, we get to insns which might not be executed - because the call might exit. This matters for insns that trap. - Constant and pure call insns always return, so they don't count. */ - else if (GET_CODE (p) == CALL_INSN && ! CONST_OR_PURE_CALL_P (p)) - call_passed = 1; - /* Past a label or a jump, we get to insns for which we - can't count on whether or how many times they will be - executed during each iteration. Therefore, we can - only move out sets of trivial variables - (those not used after the loop). */ - /* Similar code appears twice in strength_reduce. */ - else if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) - /* If we enter the loop in the middle, and scan around to the - beginning, don't set maybe_never for that. This must be an - unconditional jump, otherwise the code at the top of the - loop might never be executed. Unconditional jumps are - followed by a barrier then the loop_end. */ - && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop->top - && NEXT_INSN (NEXT_INSN (p)) == loop_end - && any_uncondjump_p (p))) - maybe_never = 1; - else if (GET_CODE (p) == NOTE) - { - /* At the virtual top of a converted loop, insns are again known to - be executed: logically, the loop begins here even though the exit - code has been duplicated. */ - if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0) - maybe_never = call_passed = 0; - else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG) - loop_depth++; - else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END) - loop_depth--; - } - } - - /* If one movable subsumes another, ignore that other. */ - - ignore_some_movables (movables); - - /* For each movable insn, see if the reg that it loads - leads when it dies right into another conditionally movable insn. - If so, record that the second insn "forces" the first one, - since the second can be moved only if the first is. */ - - force_movables (movables); - - /* See if there are multiple movable insns that load the same value. - If there are, make all but the first point at the first one - through the `match' field, and add the priorities of them - all together as the priority of the first. */ - - combine_movables (movables, regs); - - /* Now consider each movable insn to decide whether it is worth moving. - Store 0 in regs->array[I].set_in_loop for each reg I that is moved. - - For machines with few registers this increases code size, so do not - move moveables when optimizing for code size on such machines. - (The 18 below is the value for i386.) */ - - if (!optimize_size - || (reg_class_size[GENERAL_REGS] > 18 && !loop_info->has_call)) - { - move_movables (loop, movables, threshold, insn_count); - - /* Recalculate regs->array if move_movables has created new - registers. */ - if (max_reg_num () > regs->num) - { - loop_regs_scan (loop, 0); - for (update_start = loop_start; - PREV_INSN (update_start) - && GET_CODE (PREV_INSN (update_start)) != CODE_LABEL; - update_start = PREV_INSN (update_start)) - ; - update_end = NEXT_INSN (loop_end); - - reg_scan_update (update_start, update_end, loop_max_reg); - loop_max_reg = max_reg_num (); - } - } - - /* Now candidates that still are negative are those not moved. - Change regs->array[I].set_in_loop to indicate that those are not actually - invariant. */ - for (i = 0; i < regs->num; i++) - if (regs->array[i].set_in_loop < 0) - regs->array[i].set_in_loop = regs->array[i].n_times_set; - - /* Now that we've moved some things out of the loop, we might be able to - hoist even more memory references. */ - load_mems (loop); - - /* Recalculate regs->array if load_mems has created new registers. */ - if (max_reg_num () > regs->num) - loop_regs_scan (loop, 0); - - for (update_start = loop_start; - PREV_INSN (update_start) - && GET_CODE (PREV_INSN (update_start)) != CODE_LABEL; - update_start = PREV_INSN (update_start)) - ; - update_end = NEXT_INSN (loop_end); - - reg_scan_update (update_start, update_end, loop_max_reg); - loop_max_reg = max_reg_num (); - - if (flag_strength_reduce) - { - if (update_end && GET_CODE (update_end) == CODE_LABEL) - /* Ensure our label doesn't go away. */ - LABEL_NUSES (update_end)++; - - strength_reduce (loop, flags); - - reg_scan_update (update_start, update_end, loop_max_reg); - loop_max_reg = max_reg_num (); - - if (update_end && GET_CODE (update_end) == CODE_LABEL - && --LABEL_NUSES (update_end) == 0) - delete_related_insns (update_end); - } - - - /* The movable information is required for strength reduction. */ - loop_movables_free (movables); - - free (regs->array); - regs->array = 0; - regs->num = 0; -} - -/* Add elements to *OUTPUT to record all the pseudo-regs - mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */ - -void -record_excess_regs (rtx in_this, rtx not_in_this, rtx *output) -{ - enum rtx_code code; - const char *fmt; - int i; - - code = GET_CODE (in_this); - - switch (code) - { - case PC: - case CC0: - case CONST_INT: - case CONST_DOUBLE: - case CONST: - case SYMBOL_REF: - case LABEL_REF: - return; - - case REG: - if (REGNO (in_this) >= FIRST_PSEUDO_REGISTER - && ! reg_mentioned_p (in_this, not_in_this)) - *output = gen_rtx_EXPR_LIST (VOIDmode, in_this, *output); - return; - - default: - break; - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - int j; - - switch (fmt[i]) - { - case 'E': - for (j = 0; j < XVECLEN (in_this, i); j++) - record_excess_regs (XVECEXP (in_this, i, j), not_in_this, output); - break; - - case 'e': - record_excess_regs (XEXP (in_this, i), not_in_this, output); - break; - } - } -} - -/* Check what regs are referred to in the libcall block ending with INSN, - aside from those mentioned in the equivalent value. - If there are none, return 0. - If there are one or more, return an EXPR_LIST containing all of them. */ - -rtx -libcall_other_reg (rtx insn, rtx equiv) -{ - rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX); - rtx p = XEXP (note, 0); - rtx output = 0; - - /* First, find all the regs used in the libcall block - that are not mentioned as inputs to the result. */ - - while (p != insn) - { - if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN - || GET_CODE (p) == CALL_INSN) - record_excess_regs (PATTERN (p), equiv, &output); - p = NEXT_INSN (p); - } - - return output; -} - -/* Return 1 if all uses of REG - are between INSN and the end of the basic block. */ - -static int -reg_in_basic_block_p (rtx insn, rtx reg) -{ - int regno = REGNO (reg); - rtx p; - - if (REGNO_FIRST_UID (regno) != INSN_UID (insn)) - return 0; - - /* Search this basic block for the already recorded last use of the reg. */ - for (p = insn; p; p = NEXT_INSN (p)) - { - switch (GET_CODE (p)) - { - case NOTE: - break; - - case INSN: - case CALL_INSN: - /* Ordinary insn: if this is the last use, we win. */ - if (REGNO_LAST_UID (regno) == INSN_UID (p)) - return 1; - break; - - case JUMP_INSN: - /* Jump insn: if this is the last use, we win. */ - if (REGNO_LAST_UID (regno) == INSN_UID (p)) - return 1; - /* Otherwise, it's the end of the basic block, so we lose. */ - return 0; - - case CODE_LABEL: - case BARRIER: - /* It's the end of the basic block, so we lose. */ - return 0; - - default: - break; - } - } - - /* The "last use" that was recorded can't be found after the first - use. This can happen when the last use was deleted while - processing an inner loop, this inner loop was then completely - unrolled, and the outer loop is always exited after the inner loop, - so that everything after the first use becomes a single basic block. */ - return 1; -} - -/* Compute the benefit of eliminating the insns in the block whose - last insn is LAST. This may be a group of insns used to compute a - value directly or can contain a library call. */ - -static int -libcall_benefit (rtx last) -{ - rtx insn; - int benefit = 0; - - for (insn = XEXP (find_reg_note (last, REG_RETVAL, NULL_RTX), 0); - insn != last; insn = NEXT_INSN (insn)) - { - if (GET_CODE (insn) == CALL_INSN) - benefit += 10; /* Assume at least this many insns in a library - routine. */ - else if (GET_CODE (insn) == INSN - && GET_CODE (PATTERN (insn)) != USE - && GET_CODE (PATTERN (insn)) != CLOBBER) - benefit++; - } - - return benefit; -} - -/* Skip COUNT insns from INSN, counting library calls as 1 insn. */ - -static rtx -skip_consec_insns (rtx insn, int count) -{ - for (; count > 0; count--) - { - rtx temp; - - /* If first insn of libcall sequence, skip to end. */ - /* Do this at start of loop, since INSN is guaranteed to - be an insn here. */ - if (GET_CODE (insn) != NOTE - && (temp = find_reg_note (insn, REG_LIBCALL, NULL_RTX))) - insn = XEXP (temp, 0); - - do - insn = NEXT_INSN (insn); - while (GET_CODE (insn) == NOTE); - } - - return insn; -} - -/* Ignore any movable whose insn falls within a libcall - which is part of another movable. - We make use of the fact that the movable for the libcall value - was made later and so appears later on the chain. */ - -static void -ignore_some_movables (struct loop_movables *movables) -{ - struct movable *m, *m1; - - for (m = movables->head; m; m = m->next) - { - /* Is this a movable for the value of a libcall? */ - rtx note = find_reg_note (m->insn, REG_RETVAL, NULL_RTX); - if (note) - { - rtx insn; - /* Check for earlier movables inside that range, - and mark them invalid. We cannot use LUIDs here because - insns created by loop.c for prior loops don't have LUIDs. - Rather than reject all such insns from movables, we just - explicitly check each insn in the libcall (since invariant - libcalls aren't that common). */ - for (insn = XEXP (note, 0); insn != m->insn; insn = NEXT_INSN (insn)) - for (m1 = movables->head; m1 != m; m1 = m1->next) - if (m1->insn == insn) - m1->done = 1; - } - } -} - -/* For each movable insn, see if the reg that it loads - leads when it dies right into another conditionally movable insn. - If so, record that the second insn "forces" the first one, - since the second can be moved only if the first is. */ - -static void -force_movables (struct loop_movables *movables) -{ - struct movable *m, *m1; - - for (m1 = movables->head; m1; m1 = m1->next) - /* Omit this if moving just the (SET (REG) 0) of a zero-extend. */ - if (!m1->partial && !m1->done) - { - int regno = m1->regno; - for (m = m1->next; m; m = m->next) - /* ??? Could this be a bug? What if CSE caused the - register of M1 to be used after this insn? - Since CSE does not update regno_last_uid, - this insn M->insn might not be where it dies. - But very likely this doesn't matter; what matters is - that M's reg is computed from M1's reg. */ - if (INSN_UID (m->insn) == REGNO_LAST_UID (regno) - && !m->done) - break; - if (m != 0 && m->set_src == m1->set_dest - /* If m->consec, m->set_src isn't valid. */ - && m->consec == 0) - m = 0; - - /* Increase the priority of the moving the first insn - since it permits the second to be moved as well. - Likewise for insns already forced by the first insn. */ - if (m != 0) - { - struct movable *m2; - - m->forces = m1; - for (m2 = m1; m2; m2 = m2->forces) - { - m2->lifetime += m->lifetime; - m2->savings += m->savings; - } - } - } -} - -/* Find invariant expressions that are equal and can be combined into - one register. */ - -static void -combine_movables (struct loop_movables *movables, struct loop_regs *regs) -{ - struct movable *m; - char *matched_regs = xmalloc (regs->num); - enum machine_mode mode; - - /* Regs that are set more than once are not allowed to match - or be matched. I'm no longer sure why not. */ - /* Only pseudo registers are allowed to match or be matched, - since move_movables does not validate the change. */ - /* Perhaps testing m->consec_sets would be more appropriate here? */ - - for (m = movables->head; m; m = m->next) - if (m->match == 0 && regs->array[m->regno].n_times_set == 1 - && m->regno >= FIRST_PSEUDO_REGISTER - && !m->insert_temp - && !m->partial) - { - struct movable *m1; - int regno = m->regno; - - memset (matched_regs, 0, regs->num); - matched_regs[regno] = 1; - - /* We want later insns to match the first one. Don't make the first - one match any later ones. So start this loop at m->next. */ - for (m1 = m->next; m1; m1 = m1->next) - if (m != m1 && m1->match == 0 - && !m1->insert_temp - && regs->array[m1->regno].n_times_set == 1 - && m1->regno >= FIRST_PSEUDO_REGISTER - /* A reg used outside the loop mustn't be eliminated. */ - && !m1->global - /* A reg used for zero-extending mustn't be eliminated. */ - && !m1->partial - && (matched_regs[m1->regno] - || - ( - /* Can combine regs with different modes loaded from the - same constant only if the modes are the same or - if both are integer modes with M wider or the same - width as M1. The check for integer is redundant, but - safe, since the only case of differing destination - modes with equal sources is when both sources are - VOIDmode, i.e., CONST_INT. */ - (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest) - || (GET_MODE_CLASS (GET_MODE (m->set_dest)) == MODE_INT - && GET_MODE_CLASS (GET_MODE (m1->set_dest)) == MODE_INT - && (GET_MODE_BITSIZE (GET_MODE (m->set_dest)) - >= GET_MODE_BITSIZE (GET_MODE (m1->set_dest))))) - /* See if the source of M1 says it matches M. */ - && ((GET_CODE (m1->set_src) == REG - && matched_regs[REGNO (m1->set_src)]) - || rtx_equal_for_loop_p (m->set_src, m1->set_src, - movables, regs)))) - && ((m->dependencies == m1->dependencies) - || rtx_equal_p (m->dependencies, m1->dependencies))) - { - m->lifetime += m1->lifetime; - m->savings += m1->savings; - m1->done = 1; - m1->match = m; - matched_regs[m1->regno] = 1; - } - } - - /* Now combine the regs used for zero-extension. - This can be done for those not marked `global' - provided their lives don't overlap. */ - - for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode; - mode = GET_MODE_WIDER_MODE (mode)) - { - struct movable *m0 = 0; - - /* Combine all the registers for extension from mode MODE. - Don't combine any that are used outside this loop. */ - for (m = movables->head; m; m = m->next) - if (m->partial && ! m->global - && mode == GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m->insn))))) - { - struct movable *m1; - - int first = REGNO_FIRST_LUID (m->regno); - int last = REGNO_LAST_LUID (m->regno); - - if (m0 == 0) - { - /* First one: don't check for overlap, just record it. */ - m0 = m; - continue; - } - - /* Make sure they extend to the same mode. - (Almost always true.) */ - if (GET_MODE (m->set_dest) != GET_MODE (m0->set_dest)) - continue; - - /* We already have one: check for overlap with those - already combined together. */ - for (m1 = movables->head; m1 != m; m1 = m1->next) - if (m1 == m0 || (m1->partial && m1->match == m0)) - if (! (REGNO_FIRST_LUID (m1->regno) > last - || REGNO_LAST_LUID (m1->regno) < first)) - goto overlap; - - /* No overlap: we can combine this with the others. */ - m0->lifetime += m->lifetime; - m0->savings += m->savings; - m->done = 1; - m->match = m0; - - overlap: - ; - } - } - - /* Clean up. */ - free (matched_regs); -} - -/* Returns the number of movable instructions in LOOP that were not - moved outside the loop. */ - -static int -num_unmoved_movables (const struct loop *loop) -{ - int num = 0; - struct movable *m; - - for (m = LOOP_MOVABLES (loop)->head; m; m = m->next) - if (!m->done) - ++num; - - return num; -} - - -/* Return 1 if regs X and Y will become the same if moved. */ - -static int -regs_match_p (rtx x, rtx y, struct loop_movables *movables) -{ - unsigned int xn = REGNO (x); - unsigned int yn = REGNO (y); - struct movable *mx, *my; - - for (mx = movables->head; mx; mx = mx->next) - if (mx->regno == xn) - break; - - for (my = movables->head; my; my = my->next) - if (my->regno == yn) - break; - - return (mx && my - && ((mx->match == my->match && mx->match != 0) - || mx->match == my - || mx == my->match)); -} - -/* Return 1 if X and Y are identical-looking rtx's. - This is the Lisp function EQUAL for rtx arguments. - - If two registers are matching movables or a movable register and an - equivalent constant, consider them equal. */ - -static int -rtx_equal_for_loop_p (rtx x, rtx y, struct loop_movables *movables, - struct loop_regs *regs) -{ - int i; - int j; - struct movable *m; - enum rtx_code code; - const char *fmt; - - if (x == y) - return 1; - if (x == 0 || y == 0) - return 0; - - code = GET_CODE (x); - - /* If we have a register and a constant, they may sometimes be - equal. */ - if (GET_CODE (x) == REG && regs->array[REGNO (x)].set_in_loop == -2 - && CONSTANT_P (y)) - { - for (m = movables->head; m; m = m->next) - if (m->move_insn && m->regno == REGNO (x) - && rtx_equal_p (m->set_src, y)) - return 1; - } - else if (GET_CODE (y) == REG && regs->array[REGNO (y)].set_in_loop == -2 - && CONSTANT_P (x)) - { - for (m = movables->head; m; m = m->next) - if (m->move_insn && m->regno == REGNO (y) - && rtx_equal_p (m->set_src, x)) - return 1; - } - - /* Otherwise, rtx's of different codes cannot be equal. */ - if (code != GET_CODE (y)) - return 0; - - /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. - (REG:SI x) and (REG:HI x) are NOT equivalent. */ - - if (GET_MODE (x) != GET_MODE (y)) - return 0; - - /* These three types of rtx's can be compared nonrecursively. */ - if (code == REG) - return (REGNO (x) == REGNO (y) || regs_match_p (x, y, movables)); - - if (code == LABEL_REF) - return XEXP (x, 0) == XEXP (y, 0); - if (code == SYMBOL_REF) - return XSTR (x, 0) == XSTR (y, 0); - - /* Compare the elements. If any pair of corresponding elements - fail to match, return 0 for the whole things. */ - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - switch (fmt[i]) - { - case 'w': - if (XWINT (x, i) != XWINT (y, i)) - return 0; - break; - - case 'i': - if (XINT (x, i) != XINT (y, i)) - return 0; - break; - - case 'E': - /* Two vectors must have the same length. */ - if (XVECLEN (x, i) != XVECLEN (y, i)) - return 0; - - /* And the corresponding elements must match. */ - for (j = 0; j < XVECLEN (x, i); j++) - if (rtx_equal_for_loop_p (XVECEXP (x, i, j), XVECEXP (y, i, j), - movables, regs) == 0) - return 0; - break; - - case 'e': - if (rtx_equal_for_loop_p (XEXP (x, i), XEXP (y, i), movables, regs) - == 0) - return 0; - break; - - case 's': - if (strcmp (XSTR (x, i), XSTR (y, i))) - return 0; - break; - - case 'u': - /* These are just backpointers, so they don't matter. */ - break; - - case '0': - break; - - /* It is believed that rtx's at this level will never - contain anything but integers and other rtx's, - except for within LABEL_REFs and SYMBOL_REFs. */ - default: - abort (); - } - } - return 1; -} - -/* If X contains any LABEL_REF's, add REG_LABEL notes for them to all - insns in INSNS which use the reference. LABEL_NUSES for CODE_LABEL - references is incremented once for each added note. */ - -static void -add_label_notes (rtx x, rtx insns) -{ - enum rtx_code code = GET_CODE (x); - int i, j; - const char *fmt; - rtx insn; - - if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) - { - /* This code used to ignore labels that referred to dispatch tables to - avoid flow generating (slightly) worse code. - - We no longer ignore such label references (see LABEL_REF handling in - mark_jump_label for additional information). */ - for (insn = insns; insn; insn = NEXT_INSN (insn)) - if (reg_mentioned_p (XEXP (x, 0), insn)) - { - REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0), - REG_NOTES (insn)); - if (LABEL_P (XEXP (x, 0))) - LABEL_NUSES (XEXP (x, 0))++; - } - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - add_label_notes (XEXP (x, i), insns); - else if (fmt[i] == 'E') - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - add_label_notes (XVECEXP (x, i, j), insns); - } -} - -/* Scan MOVABLES, and move the insns that deserve to be moved. - If two matching movables are combined, replace one reg with the - other throughout. */ - -static void -move_movables (struct loop *loop, struct loop_movables *movables, - int threshold, int insn_count) -{ - struct loop_regs *regs = LOOP_REGS (loop); - int nregs = regs->num; - rtx new_start = 0; - struct movable *m; - rtx p; - rtx loop_start = loop->start; - rtx loop_end = loop->end; - /* Map of pseudo-register replacements to handle combining - when we move several insns that load the same value - into different pseudo-registers. */ - rtx *reg_map = xcalloc (nregs, sizeof (rtx)); - char *already_moved = xcalloc (nregs, sizeof (char)); - - for (m = movables->head; m; m = m->next) - { - /* Describe this movable insn. */ - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "Insn %d: regno %d (life %d), ", - INSN_UID (m->insn), m->regno, m->lifetime); - if (m->consec > 0) - fprintf (loop_dump_stream, "consec %d, ", m->consec); - if (m->cond) - fprintf (loop_dump_stream, "cond "); - if (m->force) - fprintf (loop_dump_stream, "force "); - if (m->global) - fprintf (loop_dump_stream, "global "); - if (m->done) - fprintf (loop_dump_stream, "done "); - if (m->move_insn) - fprintf (loop_dump_stream, "move-insn "); - if (m->match) - fprintf (loop_dump_stream, "matches %d ", - INSN_UID (m->match->insn)); - if (m->forces) - fprintf (loop_dump_stream, "forces %d ", - INSN_UID (m->forces->insn)); - } - - /* Ignore the insn if it's already done (it matched something else). - Otherwise, see if it is now safe to move. */ - - if (!m->done - && (! m->cond - || (1 == loop_invariant_p (loop, m->set_src) - && (m->dependencies == 0 - || 1 == loop_invariant_p (loop, m->dependencies)) - && (m->consec == 0 - || 1 == consec_sets_invariant_p (loop, m->set_dest, - m->consec + 1, - m->insn)))) - && (! m->forces || m->forces->done)) - { - int regno; - rtx p; - int savings = m->savings; - - /* We have an insn that is safe to move. - Compute its desirability. */ - - p = m->insn; - regno = m->regno; - - if (loop_dump_stream) - fprintf (loop_dump_stream, "savings %d ", savings); - - if (regs->array[regno].moved_once && loop_dump_stream) - fprintf (loop_dump_stream, "halved since already moved "); - - /* An insn MUST be moved if we already moved something else - which is safe only if this one is moved too: that is, - if already_moved[REGNO] is nonzero. */ - - /* An insn is desirable to move if the new lifetime of the - register is no more than THRESHOLD times the old lifetime. - If it's not desirable, it means the loop is so big - that moving won't speed things up much, - and it is liable to make register usage worse. */ - - /* It is also desirable to move if it can be moved at no - extra cost because something else was already moved. */ - - if (already_moved[regno] - || flag_move_all_movables - || (threshold * savings * m->lifetime) >= - (regs->array[regno].moved_once ? insn_count * 2 : insn_count) - || (m->forces && m->forces->done - && regs->array[m->forces->regno].n_times_set == 1)) - { - int count; - struct movable *m1; - rtx first = NULL_RTX; - rtx newreg = NULL_RTX; - - if (m->insert_temp) - newreg = gen_reg_rtx (GET_MODE (m->set_dest)); - - /* Now move the insns that set the reg. */ - - if (m->partial && m->match) - { - rtx newpat, i1; - rtx r1, r2; - /* Find the end of this chain of matching regs. - Thus, we load each reg in the chain from that one reg. - And that reg is loaded with 0 directly, - since it has ->match == 0. */ - for (m1 = m; m1->match; m1 = m1->match); - newpat = gen_move_insn (SET_DEST (PATTERN (m->insn)), - SET_DEST (PATTERN (m1->insn))); - i1 = loop_insn_hoist (loop, newpat); - - /* Mark the moved, invariant reg as being allowed to - share a hard reg with the other matching invariant. */ - REG_NOTES (i1) = REG_NOTES (m->insn); - r1 = SET_DEST (PATTERN (m->insn)); - r2 = SET_DEST (PATTERN (m1->insn)); - regs_may_share - = gen_rtx_EXPR_LIST (VOIDmode, r1, - gen_rtx_EXPR_LIST (VOIDmode, r2, - regs_may_share)); - delete_insn (m->insn); - - if (new_start == 0) - new_start = i1; - - if (loop_dump_stream) - fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); - } - /* If we are to re-generate the item being moved with a - new move insn, first delete what we have and then emit - the move insn before the loop. */ - else if (m->move_insn) - { - rtx i1, temp, seq; - - for (count = m->consec; count >= 0; count--) - { - /* If this is the first insn of a library call sequence, - something is very wrong. */ - if (GET_CODE (p) != NOTE - && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) - abort (); - - /* If this is the last insn of a libcall sequence, then - delete every insn in the sequence except the last. - The last insn is handled in the normal manner. */ - if (GET_CODE (p) != NOTE - && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) - { - temp = XEXP (temp, 0); - while (temp != p) - temp = delete_insn (temp); - } - - temp = p; - p = delete_insn (p); - - /* simplify_giv_expr expects that it can walk the insns - at m->insn forwards and see this old sequence we are - tossing here. delete_insn does preserve the next - pointers, but when we skip over a NOTE we must fix - it up. Otherwise that code walks into the non-deleted - insn stream. */ - while (p && GET_CODE (p) == NOTE) - p = NEXT_INSN (temp) = NEXT_INSN (p); - - if (m->insert_temp) - { - /* Replace the original insn with a move from - our newly created temp. */ - start_sequence (); - emit_move_insn (m->set_dest, newreg); - seq = get_insns (); - end_sequence (); - emit_insn_before (seq, p); - } - } - - start_sequence (); - emit_move_insn (m->insert_temp ? newreg : m->set_dest, - m->set_src); - seq = get_insns (); - end_sequence (); - - add_label_notes (m->set_src, seq); - - i1 = loop_insn_hoist (loop, seq); - if (! find_reg_note (i1, REG_EQUAL, NULL_RTX)) - set_unique_reg_note (i1, - m->is_equiv ? REG_EQUIV : REG_EQUAL, - m->set_src); - - if (loop_dump_stream) - fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); - - /* The more regs we move, the less we like moving them. */ - threshold -= 3; - } - else - { - for (count = m->consec; count >= 0; count--) - { - rtx i1, temp; - - /* If first insn of libcall sequence, skip to end. */ - /* Do this at start of loop, since p is guaranteed to - be an insn here. */ - if (GET_CODE (p) != NOTE - && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) - p = XEXP (temp, 0); - - /* If last insn of libcall sequence, move all - insns except the last before the loop. The last - insn is handled in the normal manner. */ - if (GET_CODE (p) != NOTE - && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) - { - rtx fn_address = 0; - rtx fn_reg = 0; - rtx fn_address_insn = 0; - - first = 0; - for (temp = XEXP (temp, 0); temp != p; - temp = NEXT_INSN (temp)) - { - rtx body; - rtx n; - rtx next; - - if (GET_CODE (temp) == NOTE) - continue; - - body = PATTERN (temp); - - /* Find the next insn after TEMP, - not counting USE or NOTE insns. */ - for (next = NEXT_INSN (temp); next != p; - next = NEXT_INSN (next)) - if (! (GET_CODE (next) == INSN - && GET_CODE (PATTERN (next)) == USE) - && GET_CODE (next) != NOTE) - break; - - /* If that is the call, this may be the insn - that loads the function address. - - Extract the function address from the insn - that loads it into a register. - If this insn was cse'd, we get incorrect code. - - So emit a new move insn that copies the - function address into the register that the - call insn will use. flow.c will delete any - redundant stores that we have created. */ - if (GET_CODE (next) == CALL_INSN - && GET_CODE (body) == SET - && GET_CODE (SET_DEST (body)) == REG - && (n = find_reg_note (temp, REG_EQUAL, - NULL_RTX))) - { - fn_reg = SET_SRC (body); - if (GET_CODE (fn_reg) != REG) - fn_reg = SET_DEST (body); - fn_address = XEXP (n, 0); - fn_address_insn = temp; - } - /* We have the call insn. - If it uses the register we suspect it might, - load it with the correct address directly. */ - if (GET_CODE (temp) == CALL_INSN - && fn_address != 0 - && reg_referenced_p (fn_reg, body)) - loop_insn_emit_after (loop, 0, fn_address_insn, - gen_move_insn - (fn_reg, fn_address)); - - if (GET_CODE (temp) == CALL_INSN) - { - i1 = loop_call_insn_hoist (loop, body); - /* Because the USAGE information potentially - contains objects other than hard registers - we need to copy it. */ - if (CALL_INSN_FUNCTION_USAGE (temp)) - CALL_INSN_FUNCTION_USAGE (i1) - = copy_rtx (CALL_INSN_FUNCTION_USAGE (temp)); - } - else - i1 = loop_insn_hoist (loop, body); - if (first == 0) - first = i1; - if (temp == fn_address_insn) - fn_address_insn = i1; - REG_NOTES (i1) = REG_NOTES (temp); - REG_NOTES (temp) = NULL; - delete_insn (temp); - } - if (new_start == 0) - new_start = first; - } - if (m->savemode != VOIDmode) - { - /* P sets REG to zero; but we should clear only - the bits that are not covered by the mode - m->savemode. */ - rtx reg = m->set_dest; - rtx sequence; - rtx tem; - - start_sequence (); - tem = expand_simple_binop - (GET_MODE (reg), AND, reg, - GEN_INT ((((HOST_WIDE_INT) 1 - << GET_MODE_BITSIZE (m->savemode))) - - 1), - reg, 1, OPTAB_LIB_WIDEN); - if (tem == 0) - abort (); - if (tem != reg) - emit_move_insn (reg, tem); - sequence = get_insns (); - end_sequence (); - i1 = loop_insn_hoist (loop, sequence); - } - else if (GET_CODE (p) == CALL_INSN) - { - i1 = loop_call_insn_hoist (loop, PATTERN (p)); - /* Because the USAGE information potentially - contains objects other than hard registers - we need to copy it. */ - if (CALL_INSN_FUNCTION_USAGE (p)) - CALL_INSN_FUNCTION_USAGE (i1) - = copy_rtx (CALL_INSN_FUNCTION_USAGE (p)); - } - else if (count == m->consec && m->move_insn_first) - { - rtx seq; - /* The SET_SRC might not be invariant, so we must - use the REG_EQUAL note. */ - start_sequence (); - emit_move_insn (m->insert_temp ? newreg : m->set_dest, - m->set_src); - seq = get_insns (); - end_sequence (); - - add_label_notes (m->set_src, seq); - - i1 = loop_insn_hoist (loop, seq); - if (! find_reg_note (i1, REG_EQUAL, NULL_RTX)) - set_unique_reg_note (i1, m->is_equiv ? REG_EQUIV - : REG_EQUAL, m->set_src); - } - else if (m->insert_temp) - { - rtx *reg_map2 = xcalloc (REGNO (newreg), - sizeof(rtx)); - reg_map2 [m->regno] = newreg; - - i1 = loop_insn_hoist (loop, copy_rtx (PATTERN (p))); - replace_regs (i1, reg_map2, REGNO (newreg), 1); - free (reg_map2); - } - else - i1 = loop_insn_hoist (loop, PATTERN (p)); - - if (REG_NOTES (i1) == 0) - { - REG_NOTES (i1) = REG_NOTES (p); - REG_NOTES (p) = NULL; - - /* If there is a REG_EQUAL note present whose value - is not loop invariant, then delete it, since it - may cause problems with later optimization passes. - It is possible for cse to create such notes - like this as a result of record_jump_cond. */ - - if ((temp = find_reg_note (i1, REG_EQUAL, NULL_RTX)) - && ! loop_invariant_p (loop, XEXP (temp, 0))) - remove_note (i1, temp); - } - - if (new_start == 0) - new_start = i1; - - if (loop_dump_stream) - fprintf (loop_dump_stream, " moved to %d", - INSN_UID (i1)); - - /* If library call, now fix the REG_NOTES that contain - insn pointers, namely REG_LIBCALL on FIRST - and REG_RETVAL on I1. */ - if ((temp = find_reg_note (i1, REG_RETVAL, NULL_RTX))) - { - XEXP (temp, 0) = first; - temp = find_reg_note (first, REG_LIBCALL, NULL_RTX); - XEXP (temp, 0) = i1; - } - - temp = p; - delete_insn (p); - p = NEXT_INSN (p); - - /* simplify_giv_expr expects that it can walk the insns - at m->insn forwards and see this old sequence we are - tossing here. delete_insn does preserve the next - pointers, but when we skip over a NOTE we must fix - it up. Otherwise that code walks into the non-deleted - insn stream. */ - while (p && GET_CODE (p) == NOTE) - p = NEXT_INSN (temp) = NEXT_INSN (p); - - if (m->insert_temp) - { - rtx seq; - /* Replace the original insn with a move from - our newly created temp. */ - start_sequence (); - emit_move_insn (m->set_dest, newreg); - seq = get_insns (); - end_sequence (); - emit_insn_before (seq, p); - } - } - - /* The more regs we move, the less we like moving them. */ - threshold -= 3; - } - - m->done = 1; - - if (!m->insert_temp) - { - /* Any other movable that loads the same register - MUST be moved. */ - already_moved[regno] = 1; - - /* This reg has been moved out of one loop. */ - regs->array[regno].moved_once = 1; - - /* The reg set here is now invariant. */ - if (! m->partial) - { - int i; - for (i = 0; i < LOOP_REGNO_NREGS (regno, m->set_dest); i++) - regs->array[regno+i].set_in_loop = 0; - } - - /* Change the length-of-life info for the register - to say it lives at least the full length of this loop. - This will help guide optimizations in outer loops. */ - - if (REGNO_FIRST_LUID (regno) > INSN_LUID (loop_start)) - /* This is the old insn before all the moved insns. - We can't use the moved insn because it is out of range - in uid_luid. Only the old insns have luids. */ - REGNO_FIRST_UID (regno) = INSN_UID (loop_start); - if (REGNO_LAST_LUID (regno) < INSN_LUID (loop_end)) - REGNO_LAST_UID (regno) = INSN_UID (loop_end); - } - - /* Combine with this moved insn any other matching movables. */ - - if (! m->partial) - for (m1 = movables->head; m1; m1 = m1->next) - if (m1->match == m) - { - rtx temp; - - /* Schedule the reg loaded by M1 - for replacement so that shares the reg of M. - If the modes differ (only possible in restricted - circumstances, make a SUBREG. - - Note this assumes that the target dependent files - treat REG and SUBREG equally, including within - GO_IF_LEGITIMATE_ADDRESS and in all the - predicates since we never verify that replacing the - original register with a SUBREG results in a - recognizable insn. */ - if (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest)) - reg_map[m1->regno] = m->set_dest; - else - reg_map[m1->regno] - = gen_lowpart_common (GET_MODE (m1->set_dest), - m->set_dest); - - /* Get rid of the matching insn - and prevent further processing of it. */ - m1->done = 1; - - /* If library call, delete all insns. */ - if ((temp = find_reg_note (m1->insn, REG_RETVAL, - NULL_RTX))) - delete_insn_chain (XEXP (temp, 0), m1->insn); - else - delete_insn (m1->insn); - - /* Any other movable that loads the same register - MUST be moved. */ - already_moved[m1->regno] = 1; - - /* The reg merged here is now invariant, - if the reg it matches is invariant. */ - if (! m->partial) - { - int i; - for (i = 0; - i < LOOP_REGNO_NREGS (regno, m1->set_dest); - i++) - regs->array[m1->regno+i].set_in_loop = 0; - } - } - } - else if (loop_dump_stream) - fprintf (loop_dump_stream, "not desirable"); - } - else if (loop_dump_stream && !m->match) - fprintf (loop_dump_stream, "not safe"); - - if (loop_dump_stream) - fprintf (loop_dump_stream, "\n"); - } - - if (new_start == 0) - new_start = loop_start; - - /* Go through all the instructions in the loop, making - all the register substitutions scheduled in REG_MAP. */ - for (p = new_start; p != loop_end; p = NEXT_INSN (p)) - if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN - || GET_CODE (p) == CALL_INSN) - { - replace_regs (PATTERN (p), reg_map, nregs, 0); - replace_regs (REG_NOTES (p), reg_map, nregs, 0); - INSN_CODE (p) = -1; - } - - /* Clean up. */ - free (reg_map); - free (already_moved); -} - - -static void -loop_movables_add (struct loop_movables *movables, struct movable *m) -{ - if (movables->head == 0) - movables->head = m; - else - movables->last->next = m; - movables->last = m; -} - - -static void -loop_movables_free (struct loop_movables *movables) -{ - struct movable *m; - struct movable *m_next; - - for (m = movables->head; m; m = m_next) - { - m_next = m->next; - free (m); - } -} - -#if 0 -/* Scan X and replace the address of any MEM in it with ADDR. - REG is the address that MEM should have before the replacement. */ - -static void -replace_call_address (rtx x, rtx reg, rtx addr) -{ - enum rtx_code code; - int i; - const char *fmt; - - if (x == 0) - return; - code = GET_CODE (x); - switch (code) - { - case PC: - case CC0: - case CONST_INT: - case CONST_DOUBLE: - case CONST: - case SYMBOL_REF: - case LABEL_REF: - case REG: - return; - - case SET: - /* Short cut for very common case. */ - replace_call_address (XEXP (x, 1), reg, addr); - return; - - case CALL: - /* Short cut for very common case. */ - replace_call_address (XEXP (x, 0), reg, addr); - return; - - case MEM: - /* If this MEM uses a reg other than the one we expected, - something is wrong. */ - if (XEXP (x, 0) != reg) - abort (); - XEXP (x, 0) = addr; - return; - - default: - break; - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - replace_call_address (XEXP (x, i), reg, addr); - else if (fmt[i] == 'E') - { - int j; - for (j = 0; j < XVECLEN (x, i); j++) - replace_call_address (XVECEXP (x, i, j), reg, addr); - } - } -} -#endif - -/* Return the number of memory refs to addresses that vary - in the rtx X. */ - -static int -count_nonfixed_reads (const struct loop *loop, rtx x) -{ - enum rtx_code code; - int i; - const char *fmt; - int value; - - if (x == 0) - return 0; - - code = GET_CODE (x); - switch (code) - { - case PC: - case CC0: - case CONST_INT: - case CONST_DOUBLE: - case CONST: - case SYMBOL_REF: - case LABEL_REF: - case REG: - return 0; - - case MEM: - return ((loop_invariant_p (loop, XEXP (x, 0)) != 1) - + count_nonfixed_reads (loop, XEXP (x, 0))); - - default: - break; - } - - value = 0; - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - value += count_nonfixed_reads (loop, XEXP (x, i)); - if (fmt[i] == 'E') - { - int j; - for (j = 0; j < XVECLEN (x, i); j++) - value += count_nonfixed_reads (loop, XVECEXP (x, i, j)); - } - } - return value; -} - -/* Scan a loop setting the elements `cont', `vtop', `loops_enclosed', - `has_call', `has_nonconst_call', `has_volatile', `has_tablejump', - `unknown_address_altered', `unknown_constant_address_altered', and - `num_mem_sets' in LOOP. Also, fill in the array `mems' and the - list `store_mems' in LOOP. */ - -static void -prescan_loop (struct loop *loop) -{ - int level = 1; - rtx insn; - struct loop_info *loop_info = LOOP_INFO (loop); - rtx start = loop->start; - rtx end = loop->end; - /* The label after END. Jumping here is just like falling off the - end of the loop. We use next_nonnote_insn instead of next_label - as a hedge against the (pathological) case where some actual insn - might end up between the two. */ - rtx exit_target = next_nonnote_insn (end); - - loop_info->has_indirect_jump = indirect_jump_in_function; - loop_info->pre_header_has_call = 0; - loop_info->has_call = 0; - loop_info->has_nonconst_call = 0; - loop_info->has_prefetch = 0; - loop_info->has_volatile = 0; - loop_info->has_tablejump = 0; - loop_info->has_multiple_exit_targets = 0; - loop->level = 1; - - loop_info->unknown_address_altered = 0; - loop_info->unknown_constant_address_altered = 0; - loop_info->store_mems = NULL_RTX; - loop_info->first_loop_store_insn = NULL_RTX; - loop_info->mems_idx = 0; - loop_info->num_mem_sets = 0; - /* If loop opts run twice, this was set on 1st pass for 2nd. */ - loop_info->preconditioned = NOTE_PRECONDITIONED (end); - - for (insn = start; insn && GET_CODE (insn) != CODE_LABEL; - insn = PREV_INSN (insn)) - { - if (GET_CODE (insn) == CALL_INSN) - { - loop_info->pre_header_has_call = 1; - break; - } - } - - for (insn = NEXT_INSN (start); insn != NEXT_INSN (end); - insn = NEXT_INSN (insn)) - { - switch (GET_CODE (insn)) - { - case NOTE: - if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) - { - ++level; - /* Count number of loops contained in this one. */ - loop->level++; - } - else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) - --level; - break; - - case CALL_INSN: - if (! CONST_OR_PURE_CALL_P (insn)) - { - loop_info->unknown_address_altered = 1; - loop_info->has_nonconst_call = 1; - } - else if (pure_call_p (insn)) - loop_info->has_nonconst_call = 1; - loop_info->has_call = 1; - if (can_throw_internal (insn)) - loop_info->has_multiple_exit_targets = 1; - - /* Calls initializing constant objects have CLOBBER of MEM /u in the - attached FUNCTION_USAGE expression list, not accounted for by the - code above. We should note these to avoid missing dependencies in - later references. */ - { - rtx fusage_entry; - - for (fusage_entry = CALL_INSN_FUNCTION_USAGE (insn); - fusage_entry; fusage_entry = XEXP (fusage_entry, 1)) - { - rtx fusage = XEXP (fusage_entry, 0); - - if (GET_CODE (fusage) == CLOBBER - && GET_CODE (XEXP (fusage, 0)) == MEM - && RTX_UNCHANGING_P (XEXP (fusage, 0))) - { - note_stores (fusage, note_addr_stored, loop_info); - if (! loop_info->first_loop_store_insn - && loop_info->store_mems) - loop_info->first_loop_store_insn = insn; - } - } - } - break; - - case JUMP_INSN: - if (! loop_info->has_multiple_exit_targets) - { - rtx set = pc_set (insn); - - if (set) - { - rtx src = SET_SRC (set); - rtx label1, label2; - - if (GET_CODE (src) == IF_THEN_ELSE) - { - label1 = XEXP (src, 1); - label2 = XEXP (src, 2); - } - else - { - label1 = src; - label2 = NULL_RTX; - } - - do - { - if (label1 && label1 != pc_rtx) - { - if (GET_CODE (label1) != LABEL_REF) - { - /* Something tricky. */ - loop_info->has_multiple_exit_targets = 1; - break; - } - else if (XEXP (label1, 0) != exit_target - && LABEL_OUTSIDE_LOOP_P (label1)) - { - /* A jump outside the current loop. */ - loop_info->has_multiple_exit_targets = 1; - break; - } - } - - label1 = label2; - label2 = NULL_RTX; - } - while (label1); - } - else - { - /* A return, or something tricky. */ - loop_info->has_multiple_exit_targets = 1; - } - } - /* Fall through. */ - - case INSN: - if (volatile_refs_p (PATTERN (insn))) - loop_info->has_volatile = 1; - - if (GET_CODE (insn) == JUMP_INSN - && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC - || GET_CODE (PATTERN (insn)) == ADDR_VEC)) - loop_info->has_tablejump = 1; - - note_stores (PATTERN (insn), note_addr_stored, loop_info); - if (! loop_info->first_loop_store_insn && loop_info->store_mems) - loop_info->first_loop_store_insn = insn; - - if (flag_non_call_exceptions && can_throw_internal (insn)) - loop_info->has_multiple_exit_targets = 1; - break; - - default: - break; - } - } - - /* Now, rescan the loop, setting up the LOOP_MEMS array. */ - if (/* An exception thrown by a called function might land us - anywhere. */ - ! loop_info->has_nonconst_call - /* We don't want loads for MEMs moved to a location before the - one at which their stack memory becomes allocated. (Note - that this is not a problem for malloc, etc., since those - require actual function calls. */ - && ! current_function_calls_alloca - /* There are ways to leave the loop other than falling off the - end. */ - && ! loop_info->has_multiple_exit_targets) - for (insn = NEXT_INSN (start); insn != NEXT_INSN (end); - insn = NEXT_INSN (insn)) - for_each_rtx (&insn, insert_loop_mem, loop_info); - - /* BLKmode MEMs are added to LOOP_STORE_MEM as necessary so - that loop_invariant_p and load_mems can use true_dependence - to determine what is really clobbered. */ - if (loop_info->unknown_address_altered) - { - rtx mem = gen_rtx_MEM (BLKmode, const0_rtx); - - loop_info->store_mems - = gen_rtx_EXPR_LIST (VOIDmode, mem, loop_info->store_mems); - } - if (loop_info->unknown_constant_address_altered) - { - rtx mem = gen_rtx_MEM (BLKmode, const0_rtx); - - RTX_UNCHANGING_P (mem) = 1; - loop_info->store_mems - = gen_rtx_EXPR_LIST (VOIDmode, mem, loop_info->store_mems); - } -} - -/* Invalidate all loops containing LABEL. */ - -static void -invalidate_loops_containing_label (rtx label) -{ - struct loop *loop; - for (loop = uid_loop[INSN_UID (label)]; loop; loop = loop->outer) - loop->invalid = 1; -} - -/* Scan the function looking for loops. Record the start and end of each loop. - Also mark as invalid loops any loops that contain a setjmp or are branched - to from outside the loop. */ - -static void -find_and_verify_loops (rtx f, struct loops *loops) -{ - rtx insn; - rtx label; - int num_loops; - struct loop *current_loop; - struct loop *next_loop; - struct loop *loop; - - num_loops = loops->num; - - compute_luids (f, NULL_RTX, 0); - - /* If there are jumps to undefined labels, - treat them as jumps out of any/all loops. - This also avoids writing past end of tables when there are no loops. */ - uid_loop[0] = NULL; - - /* Find boundaries of loops, mark which loops are contained within - loops, and invalidate loops that have setjmp. */ - - num_loops = 0; - current_loop = NULL; - for (insn = f; insn; insn = NEXT_INSN (insn)) - { - if (GET_CODE (insn) == NOTE) - switch (NOTE_LINE_NUMBER (insn)) - { - case NOTE_INSN_LOOP_BEG: - next_loop = loops->array + num_loops; - next_loop->num = num_loops; - num_loops++; - next_loop->start = insn; - next_loop->outer = current_loop; - current_loop = next_loop; - break; - - case NOTE_INSN_LOOP_CONT: - current_loop->cont = insn; - break; - - case NOTE_INSN_LOOP_VTOP: - current_loop->vtop = insn; - break; - - case NOTE_INSN_LOOP_END: - if (! current_loop) - abort (); - - current_loop->end = insn; - current_loop = current_loop->outer; - break; - - default: - break; - } - - if (GET_CODE (insn) == CALL_INSN - && find_reg_note (insn, REG_SETJMP, NULL)) - { - /* In this case, we must invalidate our current loop and any - enclosing loop. */ - for (loop = current_loop; loop; loop = loop->outer) - { - loop->invalid = 1; - if (loop_dump_stream) - fprintf (loop_dump_stream, - "\nLoop at %d ignored due to setjmp.\n", - INSN_UID (loop->start)); - } - } - - /* Note that this will mark the NOTE_INSN_LOOP_END note as being in the - enclosing loop, but this doesn't matter. */ - uid_loop[INSN_UID (insn)] = current_loop; - } - - /* Any loop containing a label used in an initializer must be invalidated, - because it can be jumped into from anywhere. */ - for (label = forced_labels; label; label = XEXP (label, 1)) - invalidate_loops_containing_label (XEXP (label, 0)); - - /* Any loop containing a label used for an exception handler must be - invalidated, because it can be jumped into from anywhere. */ - for_each_eh_label (invalidate_loops_containing_label); - - /* Now scan all insn's in the function. If any JUMP_INSN branches into a - loop that it is not contained within, that loop is marked invalid. - If any INSN or CALL_INSN uses a label's address, then the loop containing - that label is marked invalid, because it could be jumped into from - anywhere. - - Also look for blocks of code ending in an unconditional branch that - exits the loop. If such a block is surrounded by a conditional - branch around the block, move the block elsewhere (see below) and - invert the jump to point to the code block. This may eliminate a - label in our loop and will simplify processing by both us and a - possible second cse pass. */ - - for (insn = f; insn; insn = NEXT_INSN (insn)) - if (INSN_P (insn)) - { - struct loop *this_loop = uid_loop[INSN_UID (insn)]; - - if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN) - { - rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX); - if (note) - invalidate_loops_containing_label (XEXP (note, 0)); - } - - if (GET_CODE (insn) != JUMP_INSN) - continue; - - mark_loop_jump (PATTERN (insn), this_loop); - - /* See if this is an unconditional branch outside the loop. */ - if (this_loop - && (GET_CODE (PATTERN (insn)) == RETURN - || (any_uncondjump_p (insn) - && onlyjump_p (insn) - && (uid_loop[INSN_UID (JUMP_LABEL (insn))] - != this_loop))) - && get_max_uid () < max_uid_for_loop) - { - rtx p; - rtx our_next = next_real_insn (insn); - rtx last_insn_to_move = NEXT_INSN (insn); - struct loop *dest_loop; - struct loop *outer_loop = NULL; - - /* Go backwards until we reach the start of the loop, a label, - or a JUMP_INSN. */ - for (p = PREV_INSN (insn); - GET_CODE (p) != CODE_LABEL - && ! (GET_CODE (p) == NOTE - && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG) - && GET_CODE (p) != JUMP_INSN; - p = PREV_INSN (p)) - ; - - /* Check for the case where we have a jump to an inner nested - loop, and do not perform the optimization in that case. */ - - if (JUMP_LABEL (insn)) - { - dest_loop = uid_loop[INSN_UID (JUMP_LABEL (insn))]; - if (dest_loop) - { - for (outer_loop = dest_loop; outer_loop; - outer_loop = outer_loop->outer) - if (outer_loop == this_loop) - break; - } - } - - /* Make sure that the target of P is within the current loop. */ - - if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) - && uid_loop[INSN_UID (JUMP_LABEL (p))] != this_loop) - outer_loop = this_loop; - - /* If we stopped on a JUMP_INSN to the next insn after INSN, - we have a block of code to try to move. - - We look backward and then forward from the target of INSN - to find a BARRIER at the same loop depth as the target. - If we find such a BARRIER, we make a new label for the start - of the block, invert the jump in P and point it to that label, - and move the block of code to the spot we found. */ - - if (! outer_loop - && GET_CODE (p) == JUMP_INSN - && JUMP_LABEL (p) != 0 - /* Just ignore jumps to labels that were never emitted. - These always indicate compilation errors. */ - && INSN_UID (JUMP_LABEL (p)) != 0 - && any_condjump_p (p) && onlyjump_p (p) - && next_real_insn (JUMP_LABEL (p)) == our_next - /* If it's not safe to move the sequence, then we - mustn't try. */ - && insns_safe_to_move_p (p, NEXT_INSN (insn), - &last_insn_to_move)) - { - rtx target - = JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn (); - struct loop *target_loop = uid_loop[INSN_UID (target)]; - rtx loc, loc2; - rtx tmp; - - /* Search for possible garbage past the conditional jumps - and look for the last barrier. */ - for (tmp = last_insn_to_move; - tmp && GET_CODE (tmp) != CODE_LABEL; tmp = NEXT_INSN (tmp)) - if (GET_CODE (tmp) == BARRIER) - last_insn_to_move = tmp; - - for (loc = target; loc; loc = PREV_INSN (loc)) - if (GET_CODE (loc) == BARRIER - /* Don't move things inside a tablejump. */ - && ((loc2 = next_nonnote_insn (loc)) == 0 - || GET_CODE (loc2) != CODE_LABEL - || (loc2 = next_nonnote_insn (loc2)) == 0 - || GET_CODE (loc2) != JUMP_INSN - || (GET_CODE (PATTERN (loc2)) != ADDR_VEC - && GET_CODE (PATTERN (loc2)) != ADDR_DIFF_VEC)) - && uid_loop[INSN_UID (loc)] == target_loop) - break; - - if (loc == 0) - for (loc = target; loc; loc = NEXT_INSN (loc)) - if (GET_CODE (loc) == BARRIER - /* Don't move things inside a tablejump. */ - && ((loc2 = next_nonnote_insn (loc)) == 0 - || GET_CODE (loc2) != CODE_LABEL - || (loc2 = next_nonnote_insn (loc2)) == 0 - || GET_CODE (loc2) != JUMP_INSN - || (GET_CODE (PATTERN (loc2)) != ADDR_VEC - && GET_CODE (PATTERN (loc2)) != ADDR_DIFF_VEC)) - && uid_loop[INSN_UID (loc)] == target_loop) - break; - - if (loc) - { - rtx cond_label = JUMP_LABEL (p); - rtx new_label = get_label_after (p); - - /* Ensure our label doesn't go away. */ - LABEL_NUSES (cond_label)++; - - /* Verify that uid_loop is large enough and that - we can invert P. */ - if (invert_jump (p, new_label, 1)) - { - rtx q, r; - - /* If no suitable BARRIER was found, create a suitable - one before TARGET. Since TARGET is a fall through - path, we'll need to insert a jump around our block - and add a BARRIER before TARGET. - - This creates an extra unconditional jump outside - the loop. However, the benefits of removing rarely - executed instructions from inside the loop usually - outweighs the cost of the extra unconditional jump - outside the loop. */ - if (loc == 0) - { - rtx temp; - - temp = gen_jump (JUMP_LABEL (insn)); - temp = emit_jump_insn_before (temp, target); - JUMP_LABEL (temp) = JUMP_LABEL (insn); - LABEL_NUSES (JUMP_LABEL (insn))++; - loc = emit_barrier_before (target); - } - - /* Include the BARRIER after INSN and copy the - block after LOC. */ - if (squeeze_notes (&new_label, &last_insn_to_move)) - abort (); - reorder_insns (new_label, last_insn_to_move, loc); - - /* All those insns are now in TARGET_LOOP. */ - for (q = new_label; - q != NEXT_INSN (last_insn_to_move); - q = NEXT_INSN (q)) - uid_loop[INSN_UID (q)] = target_loop; - - /* The label jumped to by INSN is no longer a loop - exit. Unless INSN does not have a label (e.g., - it is a RETURN insn), search loop->exit_labels - to find its label_ref, and remove it. Also turn - off LABEL_OUTSIDE_LOOP_P bit. */ - if (JUMP_LABEL (insn)) - { - for (q = 0, r = this_loop->exit_labels; - r; - q = r, r = LABEL_NEXTREF (r)) - if (XEXP (r, 0) == JUMP_LABEL (insn)) - { - LABEL_OUTSIDE_LOOP_P (r) = 0; - if (q) - LABEL_NEXTREF (q) = LABEL_NEXTREF (r); - else - this_loop->exit_labels = LABEL_NEXTREF (r); - break; - } - - for (loop = this_loop; loop && loop != target_loop; - loop = loop->outer) - loop->exit_count--; - - /* If we didn't find it, then something is - wrong. */ - if (! r) - abort (); - } - - /* P is now a jump outside the loop, so it must be put - in loop->exit_labels, and marked as such. - The easiest way to do this is to just call - mark_loop_jump again for P. */ - mark_loop_jump (PATTERN (p), this_loop); - - /* If INSN now jumps to the insn after it, - delete INSN. */ - if (JUMP_LABEL (insn) != 0 - && (next_real_insn (JUMP_LABEL (insn)) - == next_real_insn (insn))) - delete_related_insns (insn); - } - - /* Continue the loop after where the conditional - branch used to jump, since the only branch insn - in the block (if it still remains) is an inter-loop - branch and hence needs no processing. */ - insn = NEXT_INSN (cond_label); - - if (--LABEL_NUSES (cond_label) == 0) - delete_related_insns (cond_label); - - /* This loop will be continued with NEXT_INSN (insn). */ - insn = PREV_INSN (insn); - } - } - } - } -} - -/* If any label in X jumps to a loop different from LOOP_NUM and any of the - loops it is contained in, mark the target loop invalid. - - For speed, we assume that X is part of a pattern of a JUMP_INSN. */ - -static void -mark_loop_jump (rtx x, struct loop *loop) -{ - struct loop *dest_loop; - struct loop *outer_loop; - int i; - - switch (GET_CODE (x)) - { - case PC: - case USE: - case CLOBBER: - case REG: - case MEM: - case CONST_INT: - case CONST_DOUBLE: - case RETURN: - return; - - case CONST: - /* There could be a label reference in here. */ - mark_loop_jump (XEXP (x, 0), loop); - return; - - case PLUS: - case MINUS: - case MULT: - mark_loop_jump (XEXP (x, 0), loop); - mark_loop_jump (XEXP (x, 1), loop); - return; - - case LO_SUM: - /* This may refer to a LABEL_REF or SYMBOL_REF. */ - mark_loop_jump (XEXP (x, 1), loop); - return; - - case SIGN_EXTEND: - case ZERO_EXTEND: - mark_loop_jump (XEXP (x, 0), loop); - return; - - case LABEL_REF: - dest_loop = uid_loop[INSN_UID (XEXP (x, 0))]; - - /* Link together all labels that branch outside the loop. This - is used by final_[bg]iv_value and the loop unrolling code. Also - mark this LABEL_REF so we know that this branch should predict - false. */ - - /* A check to make sure the label is not in an inner nested loop, - since this does not count as a loop exit. */ - if (dest_loop) - { - for (outer_loop = dest_loop; outer_loop; - outer_loop = outer_loop->outer) - if (outer_loop == loop) - break; - } - else - outer_loop = NULL; - - if (loop && ! outer_loop) - { - LABEL_OUTSIDE_LOOP_P (x) = 1; - LABEL_NEXTREF (x) = loop->exit_labels; - loop->exit_labels = x; - - for (outer_loop = loop; - outer_loop && outer_loop != dest_loop; - outer_loop = outer_loop->outer) - outer_loop->exit_count++; - } - - /* If this is inside a loop, but not in the current loop or one enclosed - by it, it invalidates at least one loop. */ - - if (! dest_loop) - return; - - /* We must invalidate every nested loop containing the target of this - label, except those that also contain the jump insn. */ - - for (; dest_loop; dest_loop = dest_loop->outer) - { - /* Stop when we reach a loop that also contains the jump insn. */ - for (outer_loop = loop; outer_loop; outer_loop = outer_loop->outer) - if (dest_loop == outer_loop) - return; - - /* If we get here, we know we need to invalidate a loop. */ - if (loop_dump_stream && ! dest_loop->invalid) - fprintf (loop_dump_stream, - "\nLoop at %d ignored due to multiple entry points.\n", - INSN_UID (dest_loop->start)); - - dest_loop->invalid = 1; - } - return; - - case SET: - /* If this is not setting pc, ignore. */ - if (SET_DEST (x) == pc_rtx) - mark_loop_jump (SET_SRC (x), loop); - return; - - case IF_THEN_ELSE: - mark_loop_jump (XEXP (x, 1), loop); - mark_loop_jump (XEXP (x, 2), loop); - return; - - case PARALLEL: - case ADDR_VEC: - for (i = 0; i < XVECLEN (x, 0); i++) - mark_loop_jump (XVECEXP (x, 0, i), loop); - return; - - case ADDR_DIFF_VEC: - for (i = 0; i < XVECLEN (x, 1); i++) - mark_loop_jump (XVECEXP (x, 1, i), loop); - return; - - default: - /* Strictly speaking this is not a jump into the loop, only a possible - jump out of the loop. However, we have no way to link the destination - of this jump onto the list of exit labels. To be safe we mark this - loop and any containing loops as invalid. */ - if (loop) - { - for (outer_loop = loop; outer_loop; outer_loop = outer_loop->outer) - { - if (loop_dump_stream && ! outer_loop->invalid) - fprintf (loop_dump_stream, - "\nLoop at %d ignored due to unknown exit jump.\n", - INSN_UID (outer_loop->start)); - outer_loop->invalid = 1; - } - } - return; - } -} - -/* Return nonzero if there is a label in the range from - insn INSN to and including the insn whose luid is END - INSN must have an assigned luid (i.e., it must not have - been previously created by loop.c). */ - -static int -labels_in_range_p (rtx insn, int end) -{ - while (insn && INSN_LUID (insn) <= end) - { - if (GET_CODE (insn) == CODE_LABEL) - return 1; - insn = NEXT_INSN (insn); - } - - return 0; -} - -/* Record that a memory reference X is being set. */ - -static void -note_addr_stored (rtx x, rtx y ATTRIBUTE_UNUSED, - void *data ATTRIBUTE_UNUSED) -{ - struct loop_info *loop_info = data; - - if (x == 0 || GET_CODE (x) != MEM) - return; - - /* Count number of memory writes. - This affects heuristics in strength_reduce. */ - loop_info->num_mem_sets++; - - /* BLKmode MEM means all memory is clobbered. */ - if (GET_MODE (x) == BLKmode) - { - if (RTX_UNCHANGING_P (x)) - loop_info->unknown_constant_address_altered = 1; - else - loop_info->unknown_address_altered = 1; - - return; - } - - loop_info->store_mems = gen_rtx_EXPR_LIST (VOIDmode, x, - loop_info->store_mems); -} - -/* X is a value modified by an INSN that references a biv inside a loop - exit test (ie, X is somehow related to the value of the biv). If X - is a pseudo that is used more than once, then the biv is (effectively) - used more than once. DATA is a pointer to a loop_regs structure. */ - -static void -note_set_pseudo_multiple_uses (rtx x, rtx y ATTRIBUTE_UNUSED, void *data) -{ - struct loop_regs *regs = (struct loop_regs *) data; - - if (x == 0) - return; - - while (GET_CODE (x) == STRICT_LOW_PART - || GET_CODE (x) == SIGN_EXTRACT - || GET_CODE (x) == ZERO_EXTRACT - || GET_CODE (x) == SUBREG) - x = XEXP (x, 0); - - if (GET_CODE (x) != REG || REGNO (x) < FIRST_PSEUDO_REGISTER) - return; - - /* If we do not have usage information, or if we know the register - is used more than once, note that fact for check_dbra_loop. */ - if (REGNO (x) >= max_reg_before_loop - || ! regs->array[REGNO (x)].single_usage - || regs->array[REGNO (x)].single_usage == const0_rtx) - regs->multiple_uses = 1; -} - -/* Return nonzero if the rtx X is invariant over the current loop. - - The value is 2 if we refer to something only conditionally invariant. - - A memory ref is invariant if it is not volatile and does not conflict - with anything stored in `loop_info->store_mems'. */ - -int -loop_invariant_p (const struct loop *loop, rtx x) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_regs *regs = LOOP_REGS (loop); - int i; - enum rtx_code code; - const char *fmt; - int conditional = 0; - rtx mem_list_entry; - - if (x == 0) - return 1; - code = GET_CODE (x); - switch (code) - { - case CONST_INT: - case CONST_DOUBLE: - case SYMBOL_REF: - case CONST: - return 1; - - case LABEL_REF: - /* A LABEL_REF is normally invariant, however, if we are unrolling - loops, and this label is inside the loop, then it isn't invariant. - This is because each unrolled copy of the loop body will have - a copy of this label. If this was invariant, then an insn loading - the address of this label into a register might get moved outside - the loop, and then each loop body would end up using the same label. - - We don't know the loop bounds here though, so just fail for all - labels. */ - if (flag_old_unroll_loops) - return 0; - else - return 1; - - case PC: - case CC0: - case UNSPEC_VOLATILE: - return 0; - - case REG: - /* We used to check RTX_UNCHANGING_P (x) here, but that is invalid - since the reg might be set by initialization within the loop. */ - - if ((x == frame_pointer_rtx || x == hard_frame_pointer_rtx - || x == arg_pointer_rtx || x == pic_offset_table_rtx) - && ! current_function_has_nonlocal_goto) - return 1; - - if (LOOP_INFO (loop)->has_call - && REGNO (x) < FIRST_PSEUDO_REGISTER && call_used_regs[REGNO (x)]) - return 0; - - /* Out-of-range regs can occur when we are called from unrolling. - These registers created by the unroller are set in the loop, - hence are never invariant. - Other out-of-range regs can be generated by load_mems; those that - are written to in the loop are not invariant, while those that are - not written to are invariant. It would be easy for load_mems - to set n_times_set correctly for these registers, however, there - is no easy way to distinguish them from registers created by the - unroller. */ - - if (REGNO (x) >= (unsigned) regs->num) - return 0; - - if (regs->array[REGNO (x)].set_in_loop < 0) - return 2; - - return regs->array[REGNO (x)].set_in_loop == 0; - - case MEM: - /* Volatile memory references must be rejected. Do this before - checking for read-only items, so that volatile read-only items - will be rejected also. */ - if (MEM_VOLATILE_P (x)) - return 0; - - /* See if there is any dependence between a store and this load. */ - mem_list_entry = loop_info->store_mems; - while (mem_list_entry) - { - if (true_dependence (XEXP (mem_list_entry, 0), VOIDmode, - x, rtx_varies_p)) - return 0; - - mem_list_entry = XEXP (mem_list_entry, 1); - } - - /* It's not invalidated by a store in memory - but we must still verify the address is invariant. */ - break; - - case ASM_OPERANDS: - /* Don't mess with insns declared volatile. */ - if (MEM_VOLATILE_P (x)) - return 0; - break; - - default: - break; - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - { - int tem = loop_invariant_p (loop, XEXP (x, i)); - if (tem == 0) - return 0; - if (tem == 2) - conditional = 1; - } - else if (fmt[i] == 'E') - { - int j; - for (j = 0; j < XVECLEN (x, i); j++) - { - int tem = loop_invariant_p (loop, XVECEXP (x, i, j)); - if (tem == 0) - return 0; - if (tem == 2) - conditional = 1; - } - - } - } - - return 1 + conditional; -} - -/* Return nonzero if all the insns in the loop that set REG - are INSN and the immediately following insns, - and if each of those insns sets REG in an invariant way - (not counting uses of REG in them). - - The value is 2 if some of these insns are only conditionally invariant. - - We assume that INSN itself is the first set of REG - and that its source is invariant. */ - -static int -consec_sets_invariant_p (const struct loop *loop, rtx reg, int n_sets, - rtx insn) -{ - struct loop_regs *regs = LOOP_REGS (loop); - rtx p = insn; - unsigned int regno = REGNO (reg); - rtx temp; - /* Number of sets we have to insist on finding after INSN. */ - int count = n_sets - 1; - int old = regs->array[regno].set_in_loop; - int value = 0; - int this; - - /* If N_SETS hit the limit, we can't rely on its value. */ - if (n_sets == 127) - return 0; - - regs->array[regno].set_in_loop = 0; - - while (count > 0) - { - enum rtx_code code; - rtx set; - - p = NEXT_INSN (p); - code = GET_CODE (p); - - /* If library call, skip to end of it. */ - if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) - p = XEXP (temp, 0); - - this = 0; - if (code == INSN - && (set = single_set (p)) - && GET_CODE (SET_DEST (set)) == REG - && REGNO (SET_DEST (set)) == regno) - { - this = loop_invariant_p (loop, SET_SRC (set)); - if (this != 0) - value |= this; - else if ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX))) - { - /* If this is a libcall, then any invariant REG_EQUAL note is OK. - If this is an ordinary insn, then only CONSTANT_P REG_EQUAL - notes are OK. */ - this = (CONSTANT_P (XEXP (temp, 0)) - || (find_reg_note (p, REG_RETVAL, NULL_RTX) - && loop_invariant_p (loop, XEXP (temp, 0)))); - if (this != 0) - value |= this; - } - } - if (this != 0) - count--; - else if (code != NOTE) - { - regs->array[regno].set_in_loop = old; - return 0; - } - } - - regs->array[regno].set_in_loop = old; - /* If loop_invariant_p ever returned 2, we return 2. */ - return 1 + (value & 2); -} - -#if 0 -/* I don't think this condition is sufficient to allow INSN - to be moved, so we no longer test it. */ - -/* Return 1 if all insns in the basic block of INSN and following INSN - that set REG are invariant according to TABLE. */ - -static int -all_sets_invariant_p (rtx reg, rtx insn, short *table) -{ - rtx p = insn; - int regno = REGNO (reg); - - while (1) - { - enum rtx_code code; - p = NEXT_INSN (p); - code = GET_CODE (p); - if (code == CODE_LABEL || code == JUMP_INSN) - return 1; - if (code == INSN && GET_CODE (PATTERN (p)) == SET - && GET_CODE (SET_DEST (PATTERN (p))) == REG - && REGNO (SET_DEST (PATTERN (p))) == regno) - { - if (! loop_invariant_p (loop, SET_SRC (PATTERN (p)), table)) - return 0; - } - } -} -#endif /* 0 */ - -/* Look at all uses (not sets) of registers in X. For each, if it is - the single use, set USAGE[REGNO] to INSN; if there was a previous use in - a different insn, set USAGE[REGNO] to const0_rtx. */ - -static void -find_single_use_in_loop (struct loop_regs *regs, rtx insn, rtx x) -{ - enum rtx_code code = GET_CODE (x); - const char *fmt = GET_RTX_FORMAT (code); - int i, j; - - if (code == REG) - regs->array[REGNO (x)].single_usage - = (regs->array[REGNO (x)].single_usage != 0 - && regs->array[REGNO (x)].single_usage != insn) - ? const0_rtx : insn; - - else if (code == SET) - { - /* Don't count SET_DEST if it is a REG; otherwise count things - in SET_DEST because if a register is partially modified, it won't - show up as a potential movable so we don't care how USAGE is set - for it. */ - if (GET_CODE (SET_DEST (x)) != REG) - find_single_use_in_loop (regs, insn, SET_DEST (x)); - find_single_use_in_loop (regs, insn, SET_SRC (x)); - } - else - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e' && XEXP (x, i) != 0) - find_single_use_in_loop (regs, insn, XEXP (x, i)); - else if (fmt[i] == 'E') - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - find_single_use_in_loop (regs, insn, XVECEXP (x, i, j)); - } -} - -/* Count and record any set in X which is contained in INSN. Update - REGS->array[I].MAY_NOT_OPTIMIZE and LAST_SET for any register I set - in X. */ - -static void -count_one_set (struct loop_regs *regs, rtx insn, rtx x, rtx *last_set) -{ - if (GET_CODE (x) == CLOBBER && GET_CODE (XEXP (x, 0)) == REG) - /* Don't move a reg that has an explicit clobber. - It's not worth the pain to try to do it correctly. */ - regs->array[REGNO (XEXP (x, 0))].may_not_optimize = 1; - - if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER) - { - rtx dest = SET_DEST (x); - while (GET_CODE (dest) == SUBREG - || GET_CODE (dest) == ZERO_EXTRACT - || GET_CODE (dest) == SIGN_EXTRACT - || GET_CODE (dest) == STRICT_LOW_PART) - dest = XEXP (dest, 0); - if (GET_CODE (dest) == REG) - { - int i; - int regno = REGNO (dest); - for (i = 0; i < LOOP_REGNO_NREGS (regno, dest); i++) - { - /* If this is the first setting of this reg - in current basic block, and it was set before, - it must be set in two basic blocks, so it cannot - be moved out of the loop. */ - if (regs->array[regno].set_in_loop > 0 - && last_set[regno] == 0) - regs->array[regno+i].may_not_optimize = 1; - /* If this is not first setting in current basic block, - see if reg was used in between previous one and this. - If so, neither one can be moved. */ - if (last_set[regno] != 0 - && reg_used_between_p (dest, last_set[regno], insn)) - regs->array[regno+i].may_not_optimize = 1; - if (regs->array[regno+i].set_in_loop < 127) - ++regs->array[regno+i].set_in_loop; - last_set[regno+i] = insn; - } - } - } -} - -/* Given a loop that is bounded by LOOP->START and LOOP->END and that - is entered at LOOP->SCAN_START, return 1 if the register set in SET - contained in insn INSN is used by any insn that precedes INSN in - cyclic order starting from the loop entry point. - - We don't want to use INSN_LUID here because if we restrict INSN to those - that have a valid INSN_LUID, it means we cannot move an invariant out - from an inner loop past two loops. */ - -static int -loop_reg_used_before_p (const struct loop *loop, rtx set, rtx insn) -{ - rtx reg = SET_DEST (set); - rtx p; - - /* Scan forward checking for register usage. If we hit INSN, we - are done. Otherwise, if we hit LOOP->END, wrap around to LOOP->START. */ - for (p = loop->scan_start; p != insn; p = NEXT_INSN (p)) - { - if (INSN_P (p) && reg_overlap_mentioned_p (reg, PATTERN (p))) - return 1; - - if (p == loop->end) - p = loop->start; - } - - return 0; -} - - -/* Information we collect about arrays that we might want to prefetch. */ -struct prefetch_info -{ - struct iv_class *class; /* Class this prefetch is based on. */ - struct induction *giv; /* GIV this prefetch is based on. */ - rtx base_address; /* Start prefetching from this address plus - index. */ - HOST_WIDE_INT index; - HOST_WIDE_INT stride; /* Prefetch stride in bytes in each - iteration. */ - unsigned int bytes_accessed; /* Sum of sizes of all accesses to this - prefetch area in one iteration. */ - unsigned int total_bytes; /* Total bytes loop will access in this block. - This is set only for loops with known - iteration counts and is 0xffffffff - otherwise. */ - int prefetch_in_loop; /* Number of prefetch insns in loop. */ - int prefetch_before_loop; /* Number of prefetch insns before loop. */ - unsigned int write : 1; /* 1 for read/write prefetches. */ -}; - -/* Data used by check_store function. */ -struct check_store_data -{ - rtx mem_address; - int mem_write; -}; - -static void check_store (rtx, rtx, void *); -static void emit_prefetch_instructions (struct loop *); -static int rtx_equal_for_prefetch_p (rtx, rtx); - -/* Set mem_write when mem_address is found. Used as callback to - note_stores. */ -static void -check_store (rtx x, rtx pat ATTRIBUTE_UNUSED, void *data) -{ - struct check_store_data *d = (struct check_store_data *) data; - - if ((GET_CODE (x) == MEM) && rtx_equal_p (d->mem_address, XEXP (x, 0))) - d->mem_write = 1; -} - -/* Like rtx_equal_p, but attempts to swap commutative operands. This is - important to get some addresses combined. Later more sophisticated - transformations can be added when necessary. - - ??? Same trick with swapping operand is done at several other places. - It can be nice to develop some common way to handle this. */ - -static int -rtx_equal_for_prefetch_p (rtx x, rtx y) -{ - int i; - int j; - enum rtx_code code = GET_CODE (x); - const char *fmt; - - if (x == y) - return 1; - if (code != GET_CODE (y)) - return 0; - - code = GET_CODE (x); - - if (GET_RTX_CLASS (code) == 'c') - { - return ((rtx_equal_for_prefetch_p (XEXP (x, 0), XEXP (y, 0)) - && rtx_equal_for_prefetch_p (XEXP (x, 1), XEXP (y, 1))) - || (rtx_equal_for_prefetch_p (XEXP (x, 0), XEXP (y, 1)) - && rtx_equal_for_prefetch_p (XEXP (x, 1), XEXP (y, 0)))); - } - /* Compare the elements. If any pair of corresponding elements fails to - match, return 0 for the whole thing. */ - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - switch (fmt[i]) - { - case 'w': - if (XWINT (x, i) != XWINT (y, i)) - return 0; - break; - - case 'i': - if (XINT (x, i) != XINT (y, i)) - return 0; - break; - - case 'E': - /* Two vectors must have the same length. */ - if (XVECLEN (x, i) != XVECLEN (y, i)) - return 0; - - /* And the corresponding elements must match. */ - for (j = 0; j < XVECLEN (x, i); j++) - if (rtx_equal_for_prefetch_p (XVECEXP (x, i, j), - XVECEXP (y, i, j)) == 0) - return 0; - break; - - case 'e': - if (rtx_equal_for_prefetch_p (XEXP (x, i), XEXP (y, i)) == 0) - return 0; - break; - - case 's': - if (strcmp (XSTR (x, i), XSTR (y, i))) - return 0; - break; - - case 'u': - /* These are just backpointers, so they don't matter. */ - break; - - case '0': - break; - - /* It is believed that rtx's at this level will never - contain anything but integers and other rtx's, - except for within LABEL_REFs and SYMBOL_REFs. */ - default: - abort (); - } - } - return 1; -} - -/* Remove constant addition value from the expression X (when present) - and return it. */ - -static HOST_WIDE_INT -remove_constant_addition (rtx *x) -{ - HOST_WIDE_INT addval = 0; - rtx exp = *x; - - /* Avoid clobbering a shared CONST expression. */ - if (GET_CODE (exp) == CONST) - { - if (GET_CODE (XEXP (exp, 0)) == PLUS - && GET_CODE (XEXP (XEXP (exp, 0), 0)) == SYMBOL_REF - && GET_CODE (XEXP (XEXP (exp, 0), 1)) == CONST_INT) - { - *x = XEXP (XEXP (exp, 0), 0); - return INTVAL (XEXP (XEXP (exp, 0), 1)); - } - return 0; - } - - if (GET_CODE (exp) == CONST_INT) - { - addval = INTVAL (exp); - *x = const0_rtx; - } - - /* For plus expression recurse on ourself. */ - else if (GET_CODE (exp) == PLUS) - { - addval += remove_constant_addition (&XEXP (exp, 0)); - addval += remove_constant_addition (&XEXP (exp, 1)); - - /* In case our parameter was constant, remove extra zero from the - expression. */ - if (XEXP (exp, 0) == const0_rtx) - *x = XEXP (exp, 1); - else if (XEXP (exp, 1) == const0_rtx) - *x = XEXP (exp, 0); - } - - return addval; -} - -/* Attempt to identify accesses to arrays that are most likely to cause cache - misses, and emit prefetch instructions a few prefetch blocks forward. - - To detect the arrays we use the GIV information that was collected by the - strength reduction pass. - - The prefetch instructions are generated after the GIV information is done - and before the strength reduction process. The new GIVs are injected into - the strength reduction tables, so the prefetch addresses are optimized as - well. - - GIVs are split into base address, stride, and constant addition values. - GIVs with the same address, stride and close addition values are combined - into a single prefetch. Also writes to GIVs are detected, so that prefetch - for write instructions can be used for the block we write to, on machines - that support write prefetches. - - Several heuristics are used to determine when to prefetch. They are - controlled by defined symbols that can be overridden for each target. */ - -static void -emit_prefetch_instructions (struct loop *loop) -{ - int num_prefetches = 0; - int num_real_prefetches = 0; - int num_real_write_prefetches = 0; - int num_prefetches_before = 0; - int num_write_prefetches_before = 0; - int ahead = 0; - int i; - struct iv_class *bl; - struct induction *iv; - struct prefetch_info info[MAX_PREFETCHES]; - struct loop_ivs *ivs = LOOP_IVS (loop); - - if (!HAVE_prefetch || PREFETCH_BLOCK == 0) - return; - - /* Consider only loops w/o calls. When a call is done, the loop is probably - slow enough to read the memory. */ - if (PREFETCH_NO_CALL && LOOP_INFO (loop)->has_call) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Prefetch: ignoring loop: has call.\n"); - - return; - } - - /* Don't prefetch in loops known to have few iterations. */ - if (PREFETCH_NO_LOW_LOOPCNT - && LOOP_INFO (loop)->n_iterations - && LOOP_INFO (loop)->n_iterations <= PREFETCH_LOW_LOOPCNT) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Prefetch: ignoring loop: not enough iterations.\n"); - return; - } - - /* Search all induction variables and pick those interesting for the prefetch - machinery. */ - for (bl = ivs->list; bl; bl = bl->next) - { - struct induction *biv = bl->biv, *biv1; - int basestride = 0; - - biv1 = biv; - - /* Expect all BIVs to be executed in each iteration. This makes our - analysis more conservative. */ - while (biv1) - { - /* Discard non-constant additions that we can't handle well yet, and - BIVs that are executed multiple times; such BIVs ought to be - handled in the nested loop. We accept not_every_iteration BIVs, - since these only result in larger strides and make our - heuristics more conservative. */ - if (GET_CODE (biv->add_val) != CONST_INT) - { - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Prefetch: ignoring biv %d: non-constant addition at insn %d:", - REGNO (biv->src_reg), INSN_UID (biv->insn)); - print_rtl (loop_dump_stream, biv->add_val); - fprintf (loop_dump_stream, "\n"); - } - break; - } - - if (biv->maybe_multiple) - { - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Prefetch: ignoring biv %d: maybe_multiple at insn %i:", - REGNO (biv->src_reg), INSN_UID (biv->insn)); - print_rtl (loop_dump_stream, biv->add_val); - fprintf (loop_dump_stream, "\n"); - } - break; - } - - basestride += INTVAL (biv1->add_val); - biv1 = biv1->next_iv; - } - - if (biv1 || !basestride) - continue; - - for (iv = bl->giv; iv; iv = iv->next_iv) - { - rtx address; - rtx temp; - HOST_WIDE_INT index = 0; - int add = 1; - HOST_WIDE_INT stride = 0; - int stride_sign = 1; - struct check_store_data d; - const char *ignore_reason = NULL; - int size = GET_MODE_SIZE (GET_MODE (iv)); - - /* See whether an induction variable is interesting to us and if - not, report the reason. */ - if (iv->giv_type != DEST_ADDR) - ignore_reason = "giv is not a destination address"; - - /* We are interested only in constant stride memory references - in order to be able to compute density easily. */ - else if (GET_CODE (iv->mult_val) != CONST_INT) - ignore_reason = "stride is not constant"; - - else - { - stride = INTVAL (iv->mult_val) * basestride; - if (stride < 0) - { - stride = -stride; - stride_sign = -1; - } - - /* On some targets, reversed order prefetches are not - worthwhile. */ - if (PREFETCH_NO_REVERSE_ORDER && stride_sign < 0) - ignore_reason = "reversed order stride"; - - /* Prefetch of accesses with an extreme stride might not be - worthwhile, either. */ - else if (PREFETCH_NO_EXTREME_STRIDE - && stride > PREFETCH_EXTREME_STRIDE) - ignore_reason = "extreme stride"; - - /* Ignore GIVs with varying add values; we can't predict the - value for the next iteration. */ - else if (!loop_invariant_p (loop, iv->add_val)) - ignore_reason = "giv has varying add value"; - - /* Ignore GIVs in the nested loops; they ought to have been - handled already. */ - else if (iv->maybe_multiple) - ignore_reason = "giv is in nested loop"; - } - - if (ignore_reason != NULL) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Prefetch: ignoring giv at %d: %s.\n", - INSN_UID (iv->insn), ignore_reason); - continue; - } - - /* Determine the pointer to the basic array we are examining. It is - the sum of the BIV's initial value and the GIV's add_val. */ - address = copy_rtx (iv->add_val); - temp = copy_rtx (bl->initial_value); - - address = simplify_gen_binary (PLUS, Pmode, temp, address); - index = remove_constant_addition (&address); - - d.mem_write = 0; - d.mem_address = *iv->location; - - /* When the GIV is not always executed, we might be better off by - not dirtying the cache pages. */ - if (PREFETCH_CONDITIONAL || iv->always_executed) - note_stores (PATTERN (iv->insn), check_store, &d); - else - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Prefetch: Ignoring giv at %d: %s\n", - INSN_UID (iv->insn), "in conditional code."); - continue; - } - - /* Attempt to find another prefetch to the same array and see if we - can merge this one. */ - for (i = 0; i < num_prefetches; i++) - if (rtx_equal_for_prefetch_p (address, info[i].base_address) - && stride == info[i].stride) - { - /* In case both access same array (same location - just with small difference in constant indexes), merge - the prefetches. Just do the later and the earlier will - get prefetched from previous iteration. - The artificial threshold should not be too small, - but also not bigger than small portion of memory usually - traversed by single loop. */ - if (index >= info[i].index - && index - info[i].index < PREFETCH_EXTREME_DIFFERENCE) - { - info[i].write |= d.mem_write; - info[i].bytes_accessed += size; - info[i].index = index; - info[i].giv = iv; - info[i].class = bl; - info[num_prefetches].base_address = address; - add = 0; - break; - } - - if (index < info[i].index - && info[i].index - index < PREFETCH_EXTREME_DIFFERENCE) - { - info[i].write |= d.mem_write; - info[i].bytes_accessed += size; - add = 0; - break; - } - } - - /* Merging failed. */ - if (add) - { - info[num_prefetches].giv = iv; - info[num_prefetches].class = bl; - info[num_prefetches].index = index; - info[num_prefetches].stride = stride; - info[num_prefetches].base_address = address; - info[num_prefetches].write = d.mem_write; - info[num_prefetches].bytes_accessed = size; - num_prefetches++; - if (num_prefetches >= MAX_PREFETCHES) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Maximal number of prefetches exceeded.\n"); - return; - } - } - } - } - - for (i = 0; i < num_prefetches; i++) - { - int density; - - /* Attempt to calculate the total number of bytes fetched by all - iterations of the loop. Avoid overflow. */ - if (LOOP_INFO (loop)->n_iterations - && ((unsigned HOST_WIDE_INT) (0xffffffff / info[i].stride) - >= LOOP_INFO (loop)->n_iterations)) - info[i].total_bytes = info[i].stride * LOOP_INFO (loop)->n_iterations; - else - info[i].total_bytes = 0xffffffff; - - density = info[i].bytes_accessed * 100 / info[i].stride; - - /* Prefetch might be worthwhile only when the loads/stores are dense. */ - if (PREFETCH_ONLY_DENSE_MEM) - if (density * 256 > PREFETCH_DENSE_MEM * 100 - && (info[i].total_bytes / PREFETCH_BLOCK - >= PREFETCH_BLOCKS_BEFORE_LOOP_MIN)) - { - info[i].prefetch_before_loop = 1; - info[i].prefetch_in_loop - = (info[i].total_bytes / PREFETCH_BLOCK - > PREFETCH_BLOCKS_BEFORE_LOOP_MAX); - } - else - { - info[i].prefetch_in_loop = 0, info[i].prefetch_before_loop = 0; - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Prefetch: ignoring giv at %d: %d%% density is too low.\n", - INSN_UID (info[i].giv->insn), density); - } - else - info[i].prefetch_in_loop = 1, info[i].prefetch_before_loop = 1; - - /* Find how many prefetch instructions we'll use within the loop. */ - if (info[i].prefetch_in_loop != 0) - { - info[i].prefetch_in_loop = ((info[i].stride + PREFETCH_BLOCK - 1) - / PREFETCH_BLOCK); - num_real_prefetches += info[i].prefetch_in_loop; - if (info[i].write) - num_real_write_prefetches += info[i].prefetch_in_loop; - } - } - - /* Determine how many iterations ahead to prefetch within the loop, based - on how many prefetches we currently expect to do within the loop. */ - if (num_real_prefetches != 0) - { - if ((ahead = SIMULTANEOUS_PREFETCHES / num_real_prefetches) == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Prefetch: ignoring prefetches within loop: ahead is zero; %d < %d\n", - SIMULTANEOUS_PREFETCHES, num_real_prefetches); - num_real_prefetches = 0, num_real_write_prefetches = 0; - } - } - /* We'll also use AHEAD to determine how many prefetch instructions to - emit before a loop, so don't leave it zero. */ - if (ahead == 0) - ahead = PREFETCH_BLOCKS_BEFORE_LOOP_MAX; - - for (i = 0; i < num_prefetches; i++) - { - /* Update if we've decided not to prefetch anything within the loop. */ - if (num_real_prefetches == 0) - info[i].prefetch_in_loop = 0; - - /* Find how many prefetch instructions we'll use before the loop. */ - if (info[i].prefetch_before_loop != 0) - { - int n = info[i].total_bytes / PREFETCH_BLOCK; - if (n > ahead) - n = ahead; - info[i].prefetch_before_loop = n; - num_prefetches_before += n; - if (info[i].write) - num_write_prefetches_before += n; - } - - if (loop_dump_stream) - { - if (info[i].prefetch_in_loop == 0 - && info[i].prefetch_before_loop == 0) - continue; - fprintf (loop_dump_stream, "Prefetch insn: %d", - INSN_UID (info[i].giv->insn)); - fprintf (loop_dump_stream, - "; in loop: %d; before: %d; %s\n", - info[i].prefetch_in_loop, - info[i].prefetch_before_loop, - info[i].write ? "read/write" : "read only"); - fprintf (loop_dump_stream, - " density: %d%%; bytes_accessed: %u; total_bytes: %u\n", - (int) (info[i].bytes_accessed * 100 / info[i].stride), - info[i].bytes_accessed, info[i].total_bytes); - fprintf (loop_dump_stream, " index: " HOST_WIDE_INT_PRINT_DEC - "; stride: " HOST_WIDE_INT_PRINT_DEC "; address: ", - info[i].index, info[i].stride); - print_rtl (loop_dump_stream, info[i].base_address); - fprintf (loop_dump_stream, "\n"); - } - } - - if (num_real_prefetches + num_prefetches_before > 0) - { - /* Record that this loop uses prefetch instructions. */ - LOOP_INFO (loop)->has_prefetch = 1; - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "Real prefetches needed within loop: %d (write: %d)\n", - num_real_prefetches, num_real_write_prefetches); - fprintf (loop_dump_stream, "Real prefetches needed before loop: %d (write: %d)\n", - num_prefetches_before, num_write_prefetches_before); - } - } - - for (i = 0; i < num_prefetches; i++) - { - int y; - - for (y = 0; y < info[i].prefetch_in_loop; y++) - { - rtx loc = copy_rtx (*info[i].giv->location); - rtx insn; - int bytes_ahead = PREFETCH_BLOCK * (ahead + y); - rtx before_insn = info[i].giv->insn; - rtx prev_insn = PREV_INSN (info[i].giv->insn); - rtx seq; - - /* We can save some effort by offsetting the address on - architectures with offsettable memory references. */ - if (offsettable_address_p (0, VOIDmode, loc)) - loc = plus_constant (loc, bytes_ahead); - else - { - rtx reg = gen_reg_rtx (Pmode); - loop_iv_add_mult_emit_before (loop, loc, const1_rtx, - GEN_INT (bytes_ahead), reg, - 0, before_insn); - loc = reg; - } - - start_sequence (); - /* Make sure the address operand is valid for prefetch. */ - if (! (*insn_data[(int)CODE_FOR_prefetch].operand[0].predicate) - (loc, insn_data[(int)CODE_FOR_prefetch].operand[0].mode)) - loc = force_reg (Pmode, loc); - emit_insn (gen_prefetch (loc, GEN_INT (info[i].write), - GEN_INT (3))); - seq = get_insns (); - end_sequence (); - emit_insn_before (seq, before_insn); - - /* Check all insns emitted and record the new GIV - information. */ - insn = NEXT_INSN (prev_insn); - while (insn != before_insn) - { - insn = check_insn_for_givs (loop, insn, - info[i].giv->always_executed, - info[i].giv->maybe_multiple); - insn = NEXT_INSN (insn); - } - } - - if (PREFETCH_BEFORE_LOOP) - { - /* Emit insns before the loop to fetch the first cache lines or, - if we're not prefetching within the loop, everything we expect - to need. */ - for (y = 0; y < info[i].prefetch_before_loop; y++) - { - rtx reg = gen_reg_rtx (Pmode); - rtx loop_start = loop->start; - rtx init_val = info[i].class->initial_value; - rtx add_val = simplify_gen_binary (PLUS, Pmode, - info[i].giv->add_val, - GEN_INT (y * PREFETCH_BLOCK)); - - /* Functions called by LOOP_IV_ADD_EMIT_BEFORE expect a - non-constant INIT_VAL to have the same mode as REG, which - in this case we know to be Pmode. */ - if (GET_MODE (init_val) != Pmode && !CONSTANT_P (init_val)) - { - rtx seq; - - start_sequence (); - init_val = convert_to_mode (Pmode, init_val, 0); - seq = get_insns (); - end_sequence (); - loop_insn_emit_before (loop, 0, loop_start, seq); - } - loop_iv_add_mult_emit_before (loop, init_val, - info[i].giv->mult_val, - add_val, reg, 0, loop_start); - emit_insn_before (gen_prefetch (reg, GEN_INT (info[i].write), - GEN_INT (3)), - loop_start); - } - } - } - - return; -} - -/* Communication with routines called via `note_stores'. */ - -static rtx note_insn; - -/* Dummy register to have nonzero DEST_REG for DEST_ADDR type givs. */ - -static rtx addr_placeholder; - -/* ??? Unfinished optimizations, and possible future optimizations, - for the strength reduction code. */ - -/* ??? The interaction of biv elimination, and recognition of 'constant' - bivs, may cause problems. */ - -/* ??? Add heuristics so that DEST_ADDR strength reduction does not cause - performance problems. - - Perhaps don't eliminate things that can be combined with an addressing - mode. Find all givs that have the same biv, mult_val, and add_val; - then for each giv, check to see if its only use dies in a following - memory address. If so, generate a new memory address and check to see - if it is valid. If it is valid, then store the modified memory address, - otherwise, mark the giv as not done so that it will get its own iv. */ - -/* ??? Could try to optimize branches when it is known that a biv is always - positive. */ - -/* ??? When replace a biv in a compare insn, we should replace with closest - giv so that an optimized branch can still be recognized by the combiner, - e.g. the VAX acb insn. */ - -/* ??? Many of the checks involving uid_luid could be simplified if regscan - was rerun in loop_optimize whenever a register was added or moved. - Also, some of the optimizations could be a little less conservative. */ - -/* Scan the loop body and call FNCALL for each insn. In the addition to the - LOOP and INSN parameters pass MAYBE_MULTIPLE and NOT_EVERY_ITERATION to the - callback. - - NOT_EVERY_ITERATION is 1 if current insn is not known to be executed at - least once for every loop iteration except for the last one. - - MAYBE_MULTIPLE is 1 if current insn may be executed more than once for every - loop iteration. - */ -void -for_each_insn_in_loop (struct loop *loop, loop_insn_callback fncall) -{ - int not_every_iteration = 0; - int maybe_multiple = 0; - int past_loop_latch = 0; - int loop_depth = 0; - rtx p; - - /* If loop_scan_start points to the loop exit test, we have to be wary of - subversive use of gotos inside expression statements. */ - if (prev_nonnote_insn (loop->scan_start) != prev_nonnote_insn (loop->start)) - maybe_multiple = back_branch_in_range_p (loop, loop->scan_start); - - /* Scan through loop and update NOT_EVERY_ITERATION and MAYBE_MULTIPLE. */ - for (p = next_insn_in_loop (loop, loop->scan_start); - p != NULL_RTX; - p = next_insn_in_loop (loop, p)) - { - p = fncall (loop, p, not_every_iteration, maybe_multiple); - - /* Past CODE_LABEL, we get to insns that may be executed multiple - times. The only way we can be sure that they can't is if every - jump insn between here and the end of the loop either - returns, exits the loop, is a jump to a location that is still - behind the label, or is a jump to the loop start. */ - - if (GET_CODE (p) == CODE_LABEL) - { - rtx insn = p; - - maybe_multiple = 0; - - while (1) - { - insn = NEXT_INSN (insn); - if (insn == loop->scan_start) - break; - if (insn == loop->end) - { - if (loop->top != 0) - insn = loop->top; - else - break; - if (insn == loop->scan_start) - break; - } - - if (GET_CODE (insn) == JUMP_INSN - && GET_CODE (PATTERN (insn)) != RETURN - && (!any_condjump_p (insn) - || (JUMP_LABEL (insn) != 0 - && JUMP_LABEL (insn) != loop->scan_start - && !loop_insn_first_p (p, JUMP_LABEL (insn))))) - { - maybe_multiple = 1; - break; - } - } - } - - /* Past a jump, we get to insns for which we can't count - on whether they will be executed during each iteration. */ - /* This code appears twice in strength_reduce. There is also similar - code in scan_loop. */ - if (GET_CODE (p) == JUMP_INSN - /* If we enter the loop in the middle, and scan around to the - beginning, don't set not_every_iteration for that. - This can be any kind of jump, since we want to know if insns - will be executed if the loop is executed. */ - && !(JUMP_LABEL (p) == loop->top - && ((NEXT_INSN (NEXT_INSN (p)) == loop->end - && any_uncondjump_p (p)) - || (NEXT_INSN (p) == loop->end && any_condjump_p (p))))) - { - rtx label = 0; - - /* If this is a jump outside the loop, then it also doesn't - matter. Check to see if the target of this branch is on the - loop->exits_labels list. */ - - for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label)) - if (XEXP (label, 0) == JUMP_LABEL (p)) - break; - - if (!label) - not_every_iteration = 1; - } - - else if (GET_CODE (p) == NOTE) - { - /* At the virtual top of a converted loop, insns are again known to - be executed each iteration: logically, the loop begins here - even though the exit code has been duplicated. - - Insns are also again known to be executed each iteration at - the LOOP_CONT note. */ - if ((NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP - || NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_CONT) - && loop_depth == 0) - not_every_iteration = 0; - else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG) - loop_depth++; - else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END) - loop_depth--; - } - - /* Note if we pass a loop latch. If we do, then we can not clear - NOT_EVERY_ITERATION below when we pass the last CODE_LABEL in - a loop since a jump before the last CODE_LABEL may have started - a new loop iteration. - - Note that LOOP_TOP is only set for rotated loops and we need - this check for all loops, so compare against the CODE_LABEL - which immediately follows LOOP_START. */ - if (GET_CODE (p) == JUMP_INSN - && JUMP_LABEL (p) == NEXT_INSN (loop->start)) - past_loop_latch = 1; - - /* Unlike in the code motion pass where MAYBE_NEVER indicates that - an insn may never be executed, NOT_EVERY_ITERATION indicates whether - or not an insn is known to be executed each iteration of the - loop, whether or not any iterations are known to occur. - - Therefore, if we have just passed a label and have no more labels - between here and the test insn of the loop, and we have not passed - a jump to the top of the loop, then we know these insns will be - executed each iteration. */ - - if (not_every_iteration - && !past_loop_latch - && GET_CODE (p) == CODE_LABEL - && no_labels_between_p (p, loop->end) - && loop_insn_first_p (p, loop->cont)) - not_every_iteration = 0; - } -} - -static void -loop_bivs_find (struct loop *loop) -{ - struct loop_regs *regs = LOOP_REGS (loop); - struct loop_ivs *ivs = LOOP_IVS (loop); - /* Temporary list pointers for traversing ivs->list. */ - struct iv_class *bl, **backbl; - - ivs->list = 0; - - for_each_insn_in_loop (loop, check_insn_for_bivs); - - /* Scan ivs->list to remove all regs that proved not to be bivs. - Make a sanity check against regs->n_times_set. */ - for (backbl = &ivs->list, bl = *backbl; bl; bl = bl->next) - { - if (REG_IV_TYPE (ivs, bl->regno) != BASIC_INDUCT - /* Above happens if register modified by subreg, etc. */ - /* Make sure it is not recognized as a basic induction var: */ - || regs->array[bl->regno].n_times_set != bl->biv_count - /* If never incremented, it is invariant that we decided not to - move. So leave it alone. */ - || ! bl->incremented) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Biv %d: discarded, %s\n", - bl->regno, - (REG_IV_TYPE (ivs, bl->regno) != BASIC_INDUCT - ? "not induction variable" - : (! bl->incremented ? "never incremented" - : "count error"))); - - REG_IV_TYPE (ivs, bl->regno) = NOT_BASIC_INDUCT; - *backbl = bl->next; - } - else - { - backbl = &bl->next; - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Biv %d: verified\n", bl->regno); - } - } -} - - -/* Determine how BIVS are initialized by looking through pre-header - extended basic block. */ -static void -loop_bivs_init_find (struct loop *loop) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - /* Temporary list pointers for traversing ivs->list. */ - struct iv_class *bl; - int call_seen; - rtx p; - - /* Find initial value for each biv by searching backwards from loop_start, - halting at first label. Also record any test condition. */ - - call_seen = 0; - for (p = loop->start; p && GET_CODE (p) != CODE_LABEL; p = PREV_INSN (p)) - { - rtx test; - - note_insn = p; - - if (GET_CODE (p) == CALL_INSN) - call_seen = 1; - - if (INSN_P (p)) - note_stores (PATTERN (p), record_initial, ivs); - - /* Record any test of a biv that branches around the loop if no store - between it and the start of loop. We only care about tests with - constants and registers and only certain of those. */ - if (GET_CODE (p) == JUMP_INSN - && JUMP_LABEL (p) != 0 - && next_real_insn (JUMP_LABEL (p)) == next_real_insn (loop->end) - && (test = get_condition_for_loop (loop, p)) != 0 - && GET_CODE (XEXP (test, 0)) == REG - && REGNO (XEXP (test, 0)) < max_reg_before_loop - && (bl = REG_IV_CLASS (ivs, REGNO (XEXP (test, 0)))) != 0 - && valid_initial_value_p (XEXP (test, 1), p, call_seen, loop->start) - && bl->init_insn == 0) - { - /* If an NE test, we have an initial value! */ - if (GET_CODE (test) == NE) - { - bl->init_insn = p; - bl->init_set = gen_rtx_SET (VOIDmode, - XEXP (test, 0), XEXP (test, 1)); - } - else - bl->initial_test = test; - } - } -} - - -/* Look at the each biv and see if we can say anything better about its - initial value from any initializing insns set up above. (This is done - in two passes to avoid missing SETs in a PARALLEL.) */ -static void -loop_bivs_check (struct loop *loop) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - /* Temporary list pointers for traversing ivs->list. */ - struct iv_class *bl; - struct iv_class **backbl; - - for (backbl = &ivs->list; (bl = *backbl); backbl = &bl->next) - { - rtx src; - rtx note; - - if (! bl->init_insn) - continue; - - /* IF INIT_INSN has a REG_EQUAL or REG_EQUIV note and the value - is a constant, use the value of that. */ - if (((note = find_reg_note (bl->init_insn, REG_EQUAL, 0)) != NULL - && CONSTANT_P (XEXP (note, 0))) - || ((note = find_reg_note (bl->init_insn, REG_EQUIV, 0)) != NULL - && CONSTANT_P (XEXP (note, 0)))) - src = XEXP (note, 0); - else - src = SET_SRC (bl->init_set); - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Biv %d: initialized at insn %d: initial value ", - bl->regno, INSN_UID (bl->init_insn)); - - if ((GET_MODE (src) == GET_MODE (regno_reg_rtx[bl->regno]) - || GET_MODE (src) == VOIDmode) - && valid_initial_value_p (src, bl->init_insn, - LOOP_INFO (loop)->pre_header_has_call, - loop->start)) - { - bl->initial_value = src; - - if (loop_dump_stream) - { - print_simple_rtl (loop_dump_stream, src); - fputc ('\n', loop_dump_stream); - } - } - /* If we can't make it a giv, - let biv keep initial value of "itself". */ - else if (loop_dump_stream) - fprintf (loop_dump_stream, "is complex\n"); - } -} - - -/* Search the loop for general induction variables. */ - -static void -loop_givs_find (struct loop* loop) -{ - for_each_insn_in_loop (loop, check_insn_for_givs); -} - - -/* For each giv for which we still don't know whether or not it is - replaceable, check to see if it is replaceable because its final value - can be calculated. */ - -static void -loop_givs_check (struct loop *loop) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - - for (bl = ivs->list; bl; bl = bl->next) - { - struct induction *v; - - for (v = bl->giv; v; v = v->next_iv) - if (! v->replaceable && ! v->not_replaceable) - check_final_value (loop, v); - } -} - - -/* Return nonzero if it is possible to eliminate the biv BL provided - all givs are reduced. This is possible if either the reg is not - used outside the loop, or we can compute what its final value will - be. */ - -static int -loop_biv_eliminable_p (struct loop *loop, struct iv_class *bl, - int threshold, int insn_count) -{ - /* For architectures with a decrement_and_branch_until_zero insn, - don't do this if we put a REG_NONNEG note on the endtest for this - biv. */ - -#ifdef HAVE_decrement_and_branch_until_zero - if (bl->nonneg) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Cannot eliminate nonneg biv %d.\n", bl->regno); - return 0; - } -#endif - - /* Check that biv is used outside loop or if it has a final value. - Compare against bl->init_insn rather than loop->start. We aren't - concerned with any uses of the biv between init_insn and - loop->start since these won't be affected by the value of the biv - elsewhere in the function, so long as init_insn doesn't use the - biv itself. */ - - if ((REGNO_LAST_LUID (bl->regno) < INSN_LUID (loop->end) - && bl->init_insn - && INSN_UID (bl->init_insn) < max_uid_for_loop - && REGNO_FIRST_LUID (bl->regno) >= INSN_LUID (bl->init_insn) - && ! reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set))) - || (bl->final_value = final_biv_value (loop, bl))) - return maybe_eliminate_biv (loop, bl, 0, threshold, insn_count); - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Cannot eliminate biv %d.\n", - bl->regno); - fprintf (loop_dump_stream, - "First use: insn %d, last use: insn %d.\n", - REGNO_FIRST_UID (bl->regno), - REGNO_LAST_UID (bl->regno)); - } - return 0; -} - - -/* Reduce each giv of BL that we have decided to reduce. */ - -static void -loop_givs_reduce (struct loop *loop, struct iv_class *bl) -{ - struct induction *v; - - for (v = bl->giv; v; v = v->next_iv) - { - struct induction *tv; - if (! v->ignore && v->same == 0) - { - int auto_inc_opt = 0; - - /* If the code for derived givs immediately below has already - allocated a new_reg, we must keep it. */ - if (! v->new_reg) - v->new_reg = gen_reg_rtx (v->mode); - -#ifdef AUTO_INC_DEC - /* If the target has auto-increment addressing modes, and - this is an address giv, then try to put the increment - immediately after its use, so that flow can create an - auto-increment addressing mode. */ - if (v->giv_type == DEST_ADDR && bl->biv_count == 1 - && bl->biv->always_executed && ! bl->biv->maybe_multiple - /* We don't handle reversed biv's because bl->biv->insn - does not have a valid INSN_LUID. */ - && ! bl->reversed - && v->always_executed && ! v->maybe_multiple - && INSN_UID (v->insn) < max_uid_for_loop) - { - /* If other giv's have been combined with this one, then - this will work only if all uses of the other giv's occur - before this giv's insn. This is difficult to check. - - We simplify this by looking for the common case where - there is one DEST_REG giv, and this giv's insn is the - last use of the dest_reg of that DEST_REG giv. If the - increment occurs after the address giv, then we can - perform the optimization. (Otherwise, the increment - would have to go before other_giv, and we would not be - able to combine it with the address giv to get an - auto-inc address.) */ - if (v->combined_with) - { - struct induction *other_giv = 0; - - for (tv = bl->giv; tv; tv = tv->next_iv) - if (tv->same == v) - { - if (other_giv) - break; - else - other_giv = tv; - } - if (! tv && other_giv - && REGNO (other_giv->dest_reg) < max_reg_before_loop - && (REGNO_LAST_UID (REGNO (other_giv->dest_reg)) - == INSN_UID (v->insn)) - && INSN_LUID (v->insn) < INSN_LUID (bl->biv->insn)) - auto_inc_opt = 1; - } - /* Check for case where increment is before the address - giv. Do this test in "loop order". */ - else if ((INSN_LUID (v->insn) > INSN_LUID (bl->biv->insn) - && (INSN_LUID (v->insn) < INSN_LUID (loop->scan_start) - || (INSN_LUID (bl->biv->insn) - > INSN_LUID (loop->scan_start)))) - || (INSN_LUID (v->insn) < INSN_LUID (loop->scan_start) - && (INSN_LUID (loop->scan_start) - < INSN_LUID (bl->biv->insn)))) - auto_inc_opt = -1; - else - auto_inc_opt = 1; - -#ifdef HAVE_cc0 - { - rtx prev; - - /* We can't put an insn immediately after one setting - cc0, or immediately before one using cc0. */ - if ((auto_inc_opt == 1 && sets_cc0_p (PATTERN (v->insn))) - || (auto_inc_opt == -1 - && (prev = prev_nonnote_insn (v->insn)) != 0 - && INSN_P (prev) - && sets_cc0_p (PATTERN (prev)))) - auto_inc_opt = 0; - } -#endif - - if (auto_inc_opt) - v->auto_inc_opt = 1; - } -#endif - - /* For each place where the biv is incremented, add an insn - to increment the new, reduced reg for the giv. */ - for (tv = bl->biv; tv; tv = tv->next_iv) - { - rtx insert_before; - - /* Skip if location is the same as a previous one. */ - if (tv->same) - continue; - if (! auto_inc_opt) - insert_before = NEXT_INSN (tv->insn); - else if (auto_inc_opt == 1) - insert_before = NEXT_INSN (v->insn); - else - insert_before = v->insn; - - if (tv->mult_val == const1_rtx) - loop_iv_add_mult_emit_before (loop, tv->add_val, v->mult_val, - v->new_reg, v->new_reg, - 0, insert_before); - else /* tv->mult_val == const0_rtx */ - /* A multiply is acceptable here - since this is presumed to be seldom executed. */ - loop_iv_add_mult_emit_before (loop, tv->add_val, v->mult_val, - v->add_val, v->new_reg, - 0, insert_before); - } - - /* Add code at loop start to initialize giv's reduced reg. */ - - loop_iv_add_mult_hoist (loop, - extend_value_for_giv (v, bl->initial_value), - v->mult_val, v->add_val, v->new_reg); - } - } -} - - -/* Check for givs whose first use is their definition and whose - last use is the definition of another giv. If so, it is likely - dead and should not be used to derive another giv nor to - eliminate a biv. */ - -static void -loop_givs_dead_check (struct loop *loop ATTRIBUTE_UNUSED, struct iv_class *bl) -{ - struct induction *v; - - for (v = bl->giv; v; v = v->next_iv) - { - if (v->ignore - || (v->same && v->same->ignore)) - continue; - - if (v->giv_type == DEST_REG - && REGNO_FIRST_UID (REGNO (v->dest_reg)) == INSN_UID (v->insn)) - { - struct induction *v1; - - for (v1 = bl->giv; v1; v1 = v1->next_iv) - if (REGNO_LAST_UID (REGNO (v->dest_reg)) == INSN_UID (v1->insn)) - v->maybe_dead = 1; - } - } -} - - -static void -loop_givs_rescan (struct loop *loop, struct iv_class *bl, rtx *reg_map) -{ - struct induction *v; - - for (v = bl->giv; v; v = v->next_iv) - { - if (v->same && v->same->ignore) - v->ignore = 1; - - if (v->ignore) - continue; - - /* Update expression if this was combined, in case other giv was - replaced. */ - if (v->same) - v->new_reg = replace_rtx (v->new_reg, - v->same->dest_reg, v->same->new_reg); - - /* See if this register is known to be a pointer to something. If - so, see if we can find the alignment. First see if there is a - destination register that is a pointer. If so, this shares the - alignment too. Next see if we can deduce anything from the - computational information. If not, and this is a DEST_ADDR - giv, at least we know that it's a pointer, though we don't know - the alignment. */ - if (GET_CODE (v->new_reg) == REG - && v->giv_type == DEST_REG - && REG_POINTER (v->dest_reg)) - mark_reg_pointer (v->new_reg, - REGNO_POINTER_ALIGN (REGNO (v->dest_reg))); - else if (GET_CODE (v->new_reg) == REG - && REG_POINTER (v->src_reg)) - { - unsigned int align = REGNO_POINTER_ALIGN (REGNO (v->src_reg)); - - if (align == 0 - || GET_CODE (v->add_val) != CONST_INT - || INTVAL (v->add_val) % (align / BITS_PER_UNIT) != 0) - align = 0; - - mark_reg_pointer (v->new_reg, align); - } - else if (GET_CODE (v->new_reg) == REG - && GET_CODE (v->add_val) == REG - && REG_POINTER (v->add_val)) - { - unsigned int align = REGNO_POINTER_ALIGN (REGNO (v->add_val)); - - if (align == 0 || GET_CODE (v->mult_val) != CONST_INT - || INTVAL (v->mult_val) % (align / BITS_PER_UNIT) != 0) - align = 0; - - mark_reg_pointer (v->new_reg, align); - } - else if (GET_CODE (v->new_reg) == REG && v->giv_type == DEST_ADDR) - mark_reg_pointer (v->new_reg, 0); - - if (v->giv_type == DEST_ADDR) - /* Store reduced reg as the address in the memref where we found - this giv. */ - validate_change (v->insn, v->location, v->new_reg, 0); - else if (v->replaceable) - { - reg_map[REGNO (v->dest_reg)] = v->new_reg; - } - else - { - rtx original_insn = v->insn; - rtx note; - - /* Not replaceable; emit an insn to set the original giv reg from - the reduced giv, same as above. */ - v->insn = loop_insn_emit_after (loop, 0, original_insn, - gen_move_insn (v->dest_reg, - v->new_reg)); - - /* The original insn may have a REG_EQUAL note. This note is - now incorrect and may result in invalid substitutions later. - The original insn is dead, but may be part of a libcall - sequence, which doesn't seem worth the bother of handling. */ - note = find_reg_note (original_insn, REG_EQUAL, NULL_RTX); - if (note) - remove_note (original_insn, note); - } - - /* When a loop is reversed, givs which depend on the reversed - biv, and which are live outside the loop, must be set to their - correct final value. This insn is only needed if the giv is - not replaceable. The correct final value is the same as the - value that the giv starts the reversed loop with. */ - if (bl->reversed && ! v->replaceable) - loop_iv_add_mult_sink (loop, - extend_value_for_giv (v, bl->initial_value), - v->mult_val, v->add_val, v->dest_reg); - else if (v->final_value) - loop_insn_sink_or_swim (loop, - gen_load_of_final_value (v->dest_reg, - v->final_value)); - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "giv at %d reduced to ", - INSN_UID (v->insn)); - print_simple_rtl (loop_dump_stream, v->new_reg); - fprintf (loop_dump_stream, "\n"); - } - } -} - - -static int -loop_giv_reduce_benefit (struct loop *loop ATTRIBUTE_UNUSED, - struct iv_class *bl, struct induction *v, - rtx test_reg) -{ - int add_cost; - int benefit; - - benefit = v->benefit; - PUT_MODE (test_reg, v->mode); - add_cost = iv_add_mult_cost (bl->biv->add_val, v->mult_val, - test_reg, test_reg); - - /* Reduce benefit if not replaceable, since we will insert a - move-insn to replace the insn that calculates this giv. Don't do - this unless the giv is a user variable, since it will often be - marked non-replaceable because of the duplication of the exit - code outside the loop. In such a case, the copies we insert are - dead and will be deleted. So they don't have a cost. Similar - situations exist. */ - /* ??? The new final_[bg]iv_value code does a much better job of - finding replaceable giv's, and hence this code may no longer be - necessary. */ - if (! v->replaceable && ! bl->eliminable - && REG_USERVAR_P (v->dest_reg)) - benefit -= copy_cost; - - /* Decrease the benefit to count the add-insns that we will insert - to increment the reduced reg for the giv. ??? This can - overestimate the run-time cost of the additional insns, e.g. if - there are multiple basic blocks that increment the biv, but only - one of these blocks is executed during each iteration. There is - no good way to detect cases like this with the current structure - of the loop optimizer. This code is more accurate for - determining code size than run-time benefits. */ - benefit -= add_cost * bl->biv_count; - - /* Decide whether to strength-reduce this giv or to leave the code - unchanged (recompute it from the biv each time it is used). This - decision can be made independently for each giv. */ - -#ifdef AUTO_INC_DEC - /* Attempt to guess whether autoincrement will handle some of the - new add insns; if so, increase BENEFIT (undo the subtraction of - add_cost that was done above). */ - if (v->giv_type == DEST_ADDR - /* Increasing the benefit is risky, since this is only a guess. - Avoid increasing register pressure in cases where there would - be no other benefit from reducing this giv. */ - && benefit > 0 - && GET_CODE (v->mult_val) == CONST_INT) - { - int size = GET_MODE_SIZE (GET_MODE (v->mem)); - - if (HAVE_POST_INCREMENT - && INTVAL (v->mult_val) == size) - benefit += add_cost * bl->biv_count; - else if (HAVE_PRE_INCREMENT - && INTVAL (v->mult_val) == size) - benefit += add_cost * bl->biv_count; - else if (HAVE_POST_DECREMENT - && -INTVAL (v->mult_val) == size) - benefit += add_cost * bl->biv_count; - else if (HAVE_PRE_DECREMENT - && -INTVAL (v->mult_val) == size) - benefit += add_cost * bl->biv_count; - } -#endif - - return benefit; -} - - -/* Free IV structures for LOOP. */ - -static void -loop_ivs_free (struct loop *loop) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *iv = ivs->list; - - free (ivs->regs); - - while (iv) - { - struct iv_class *next = iv->next; - struct induction *induction; - struct induction *next_induction; - - for (induction = iv->biv; induction; induction = next_induction) - { - next_induction = induction->next_iv; - free (induction); - } - for (induction = iv->giv; induction; induction = next_induction) - { - next_induction = induction->next_iv; - free (induction); - } - - free (iv); - iv = next; - } -} - - -/* Perform strength reduction and induction variable elimination. - - Pseudo registers created during this function will be beyond the - last valid index in several tables including - REGS->ARRAY[I].N_TIMES_SET and REGNO_LAST_UID. This does not cause a - problem here, because the added registers cannot be givs outside of - their loop, and hence will never be reconsidered. But scan_loop - must check regnos to make sure they are in bounds. */ - -static void -strength_reduce (struct loop *loop, int flags) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_regs *regs = LOOP_REGS (loop); - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx p; - /* Temporary list pointer for traversing ivs->list. */ - struct iv_class *bl; - /* Ratio of extra register life span we can justify - for saving an instruction. More if loop doesn't call subroutines - since in that case saving an insn makes more difference - and more registers are available. */ - /* ??? could set this to last value of threshold in move_movables */ - int threshold = (loop_info->has_call ? 1 : 2) * (3 + n_non_fixed_regs); - /* Map of pseudo-register replacements. */ - rtx *reg_map = NULL; - int reg_map_size; - int unrolled_insn_copies = 0; - rtx test_reg = gen_rtx_REG (word_mode, LAST_VIRTUAL_REGISTER + 1); - int insn_count = count_insns_in_loop (loop); - - addr_placeholder = gen_reg_rtx (Pmode); - - ivs->n_regs = max_reg_before_loop; - ivs->regs = xcalloc (ivs->n_regs, sizeof (struct iv)); - - /* Find all BIVs in loop. */ - loop_bivs_find (loop); - - /* Exit if there are no bivs. */ - if (! ivs->list) - { - /* Can still unroll the loop anyways, but indicate that there is no - strength reduction info available. */ - if (flags & LOOP_UNROLL) - unroll_loop (loop, insn_count, 0); - - loop_ivs_free (loop); - return; - } - - /* Determine how BIVS are initialized by looking through pre-header - extended basic block. */ - loop_bivs_init_find (loop); - - /* Look at the each biv and see if we can say anything better about its - initial value from any initializing insns set up above. */ - loop_bivs_check (loop); - - /* Search the loop for general induction variables. */ - loop_givs_find (loop); - - /* Try to calculate and save the number of loop iterations. This is - set to zero if the actual number can not be calculated. This must - be called after all giv's have been identified, since otherwise it may - fail if the iteration variable is a giv. */ - loop_iterations (loop); - -#ifdef HAVE_prefetch - if (flags & LOOP_PREFETCH) - emit_prefetch_instructions (loop); -#endif - - /* Now for each giv for which we still don't know whether or not it is - replaceable, check to see if it is replaceable because its final value - can be calculated. This must be done after loop_iterations is called, - so that final_giv_value will work correctly. */ - loop_givs_check (loop); - - /* Try to prove that the loop counter variable (if any) is always - nonnegative; if so, record that fact with a REG_NONNEG note - so that "decrement and branch until zero" insn can be used. */ - check_dbra_loop (loop, insn_count); - - /* Create reg_map to hold substitutions for replaceable giv regs. - Some givs might have been made from biv increments, so look at - ivs->reg_iv_type for a suitable size. */ - reg_map_size = ivs->n_regs; - reg_map = xcalloc (reg_map_size, sizeof (rtx)); - - /* Examine each iv class for feasibility of strength reduction/induction - variable elimination. */ - - for (bl = ivs->list; bl; bl = bl->next) - { - struct induction *v; - int benefit; - - /* Test whether it will be possible to eliminate this biv - provided all givs are reduced. */ - bl->eliminable = loop_biv_eliminable_p (loop, bl, threshold, insn_count); - - /* This will be true at the end, if all givs which depend on this - biv have been strength reduced. - We can't (currently) eliminate the biv unless this is so. */ - bl->all_reduced = 1; - - /* Check each extension dependent giv in this class to see if its - root biv is safe from wrapping in the interior mode. */ - check_ext_dependent_givs (loop, bl); - - /* Combine all giv's for this iv_class. */ - combine_givs (regs, bl); - - for (v = bl->giv; v; v = v->next_iv) - { - struct induction *tv; - - if (v->ignore || v->same) - continue; - - benefit = loop_giv_reduce_benefit (loop, bl, v, test_reg); - - /* If an insn is not to be strength reduced, then set its ignore - flag, and clear bl->all_reduced. */ - - /* A giv that depends on a reversed biv must be reduced if it is - used after the loop exit, otherwise, it would have the wrong - value after the loop exit. To make it simple, just reduce all - of such giv's whether or not we know they are used after the loop - exit. */ - - if (! flag_reduce_all_givs - && v->lifetime * threshold * benefit < insn_count - && ! bl->reversed) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "giv of insn %d not worth while, %d vs %d.\n", - INSN_UID (v->insn), - v->lifetime * threshold * benefit, insn_count); - v->ignore = 1; - bl->all_reduced = 0; - } - else - { - /* Check that we can increment the reduced giv without a - multiply insn. If not, reject it. */ - - for (tv = bl->biv; tv; tv = tv->next_iv) - if (tv->mult_val == const1_rtx - && ! product_cheap_p (tv->add_val, v->mult_val)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "giv of insn %d: would need a multiply.\n", - INSN_UID (v->insn)); - v->ignore = 1; - bl->all_reduced = 0; - break; - } - } - } - - /* Check for givs whose first use is their definition and whose - last use is the definition of another giv. If so, it is likely - dead and should not be used to derive another giv nor to - eliminate a biv. */ - loop_givs_dead_check (loop, bl); - - /* Reduce each giv that we decided to reduce. */ - loop_givs_reduce (loop, bl); - - /* Rescan all givs. If a giv is the same as a giv not reduced, mark it - as not reduced. - - For each giv register that can be reduced now: if replaceable, - substitute reduced reg wherever the old giv occurs; - else add new move insn "giv_reg = reduced_reg". */ - loop_givs_rescan (loop, bl, reg_map); - - /* All the givs based on the biv bl have been reduced if they - merit it. */ - - /* For each giv not marked as maybe dead that has been combined with a - second giv, clear any "maybe dead" mark on that second giv. - v->new_reg will either be or refer to the register of the giv it - combined with. - - Doing this clearing avoids problems in biv elimination where - a giv's new_reg is a complex value that can't be put in the - insn but the giv combined with (with a reg as new_reg) is - marked maybe_dead. Since the register will be used in either - case, we'd prefer it be used from the simpler giv. */ - - for (v = bl->giv; v; v = v->next_iv) - if (! v->maybe_dead && v->same) - v->same->maybe_dead = 0; - - /* Try to eliminate the biv, if it is a candidate. - This won't work if ! bl->all_reduced, - since the givs we planned to use might not have been reduced. - - We have to be careful that we didn't initially think we could - eliminate this biv because of a giv that we now think may be - dead and shouldn't be used as a biv replacement. - - Also, there is the possibility that we may have a giv that looks - like it can be used to eliminate a biv, but the resulting insn - isn't valid. This can happen, for example, on the 88k, where a - JUMP_INSN can compare a register only with zero. Attempts to - replace it with a compare with a constant will fail. - - Note that in cases where this call fails, we may have replaced some - of the occurrences of the biv with a giv, but no harm was done in - doing so in the rare cases where it can occur. */ - - if (bl->all_reduced == 1 && bl->eliminable - && maybe_eliminate_biv (loop, bl, 1, threshold, insn_count)) - { - /* ?? If we created a new test to bypass the loop entirely, - or otherwise drop straight in, based on this test, then - we might want to rewrite it also. This way some later - pass has more hope of removing the initialization of this - biv entirely. */ - - /* If final_value != 0, then the biv may be used after loop end - and we must emit an insn to set it just in case. - - Reversed bivs already have an insn after the loop setting their - value, so we don't need another one. We can't calculate the - proper final value for such a biv here anyways. */ - if (bl->final_value && ! bl->reversed) - loop_insn_sink_or_swim (loop, - gen_load_of_final_value (bl->biv->dest_reg, - bl->final_value)); - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Reg %d: biv eliminated\n", - bl->regno); - } - /* See above note wrt final_value. But since we couldn't eliminate - the biv, we must set the value after the loop instead of before. */ - else if (bl->final_value && ! bl->reversed) - loop_insn_sink (loop, gen_load_of_final_value (bl->biv->dest_reg, - bl->final_value)); - } - - /* Go through all the instructions in the loop, making all the - register substitutions scheduled in REG_MAP. */ - - for (p = loop->start; p != loop->end; p = NEXT_INSN (p)) - if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN - || GET_CODE (p) == CALL_INSN) - { - replace_regs (PATTERN (p), reg_map, reg_map_size, 0); - replace_regs (REG_NOTES (p), reg_map, reg_map_size, 0); - INSN_CODE (p) = -1; - } - - if (loop_info->n_iterations > 0) - { - /* When we completely unroll a loop we will likely not need the increment - of the loop BIV and we will not need the conditional branch at the - end of the loop. */ - unrolled_insn_copies = insn_count - 2; - -#ifdef HAVE_cc0 - /* When we completely unroll a loop on a HAVE_cc0 machine we will not - need the comparison before the conditional branch at the end of the - loop. */ - unrolled_insn_copies -= 1; -#endif - - /* We'll need one copy for each loop iteration. */ - unrolled_insn_copies *= loop_info->n_iterations; - - /* A little slop to account for the ability to remove initialization - code, better CSE, and other secondary benefits of completely - unrolling some loops. */ - unrolled_insn_copies -= 1; - - /* Clamp the value. */ - if (unrolled_insn_copies < 0) - unrolled_insn_copies = 0; - } - - /* Unroll loops from within strength reduction so that we can use the - induction variable information that strength_reduce has already - collected. Always unroll loops that would be as small or smaller - unrolled than when rolled. */ - if ((flags & LOOP_UNROLL) - || ((flags & LOOP_AUTO_UNROLL) - && loop_info->n_iterations > 0 - && unrolled_insn_copies <= insn_count)) - unroll_loop (loop, insn_count, 1); - -#ifdef HAVE_doloop_end - if (HAVE_doloop_end && (flags & LOOP_BCT) && flag_branch_on_count_reg) - doloop_optimize (loop); -#endif /* HAVE_doloop_end */ - - /* In case number of iterations is known, drop branch prediction note - in the branch. Do that only in second loop pass, as loop unrolling - may change the number of iterations performed. */ - if (flags & LOOP_BCT) - { - unsigned HOST_WIDE_INT n - = loop_info->n_iterations / loop_info->unroll_number; - if (n > 1) - predict_insn (prev_nonnote_insn (loop->end), PRED_LOOP_ITERATIONS, - REG_BR_PROB_BASE - REG_BR_PROB_BASE / n); - } - - if (loop_dump_stream) - fprintf (loop_dump_stream, "\n"); - - loop_ivs_free (loop); - if (reg_map) - free (reg_map); -} - -/*Record all basic induction variables calculated in the insn. */ -static rtx -check_insn_for_bivs (struct loop *loop, rtx p, int not_every_iteration, - int maybe_multiple) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx set; - rtx dest_reg; - rtx inc_val; - rtx mult_val; - rtx *location; - - if (GET_CODE (p) == INSN - && (set = single_set (p)) - && GET_CODE (SET_DEST (set)) == REG) - { - dest_reg = SET_DEST (set); - if (REGNO (dest_reg) < max_reg_before_loop - && REGNO (dest_reg) >= FIRST_PSEUDO_REGISTER - && REG_IV_TYPE (ivs, REGNO (dest_reg)) != NOT_BASIC_INDUCT) - { - if (basic_induction_var (loop, SET_SRC (set), - GET_MODE (SET_SRC (set)), - dest_reg, p, &inc_val, &mult_val, - &location)) - { - /* It is a possible basic induction variable. - Create and initialize an induction structure for it. */ - - struct induction *v = xmalloc (sizeof (struct induction)); - - record_biv (loop, v, p, dest_reg, inc_val, mult_val, location, - not_every_iteration, maybe_multiple); - REG_IV_TYPE (ivs, REGNO (dest_reg)) = BASIC_INDUCT; - } - else if (REGNO (dest_reg) < ivs->n_regs) - REG_IV_TYPE (ivs, REGNO (dest_reg)) = NOT_BASIC_INDUCT; - } - } - return p; -} - -/* Record all givs calculated in the insn. - A register is a giv if: it is only set once, it is a function of a - biv and a constant (or invariant), and it is not a biv. */ -static rtx -check_insn_for_givs (struct loop *loop, rtx p, int not_every_iteration, - int maybe_multiple) -{ - struct loop_regs *regs = LOOP_REGS (loop); - - rtx set; - /* Look for a general induction variable in a register. */ - if (GET_CODE (p) == INSN - && (set = single_set (p)) - && GET_CODE (SET_DEST (set)) == REG - && ! regs->array[REGNO (SET_DEST (set))].may_not_optimize) - { - rtx src_reg; - rtx dest_reg; - rtx add_val; - rtx mult_val; - rtx ext_val; - int benefit; - rtx regnote = 0; - rtx last_consec_insn; - - dest_reg = SET_DEST (set); - if (REGNO (dest_reg) < FIRST_PSEUDO_REGISTER) - return p; - - if (/* SET_SRC is a giv. */ - (general_induction_var (loop, SET_SRC (set), &src_reg, &add_val, - &mult_val, &ext_val, 0, &benefit, VOIDmode) - /* Equivalent expression is a giv. */ - || ((regnote = find_reg_note (p, REG_EQUAL, NULL_RTX)) - && general_induction_var (loop, XEXP (regnote, 0), &src_reg, - &add_val, &mult_val, &ext_val, 0, - &benefit, VOIDmode))) - /* Don't try to handle any regs made by loop optimization. - We have nothing on them in regno_first_uid, etc. */ - && REGNO (dest_reg) < max_reg_before_loop - /* Don't recognize a BASIC_INDUCT_VAR here. */ - && dest_reg != src_reg - /* This must be the only place where the register is set. */ - && (regs->array[REGNO (dest_reg)].n_times_set == 1 - /* or all sets must be consecutive and make a giv. */ - || (benefit = consec_sets_giv (loop, benefit, p, - src_reg, dest_reg, - &add_val, &mult_val, &ext_val, - &last_consec_insn)))) - { - struct induction *v = xmalloc (sizeof (struct induction)); - - /* If this is a library call, increase benefit. */ - if (find_reg_note (p, REG_RETVAL, NULL_RTX)) - benefit += libcall_benefit (p); - - /* Skip the consecutive insns, if there are any. */ - if (regs->array[REGNO (dest_reg)].n_times_set != 1) - p = last_consec_insn; - - record_giv (loop, v, p, src_reg, dest_reg, mult_val, add_val, - ext_val, benefit, DEST_REG, not_every_iteration, - maybe_multiple, (rtx*) 0); - - } - } - - /* Look for givs which are memory addresses. */ - if (GET_CODE (p) == INSN) - find_mem_givs (loop, PATTERN (p), p, not_every_iteration, - maybe_multiple); - - /* Update the status of whether giv can derive other givs. This can - change when we pass a label or an insn that updates a biv. */ - if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN - || GET_CODE (p) == CODE_LABEL) - update_giv_derive (loop, p); - return p; -} - -/* Return 1 if X is a valid source for an initial value (or as value being - compared against in an initial test). - - X must be either a register or constant and must not be clobbered between - the current insn and the start of the loop. - - INSN is the insn containing X. */ - -static int -valid_initial_value_p (rtx x, rtx insn, int call_seen, rtx loop_start) -{ - if (CONSTANT_P (x)) - return 1; - - /* Only consider pseudos we know about initialized in insns whose luids - we know. */ - if (GET_CODE (x) != REG - || REGNO (x) >= max_reg_before_loop) - return 0; - - /* Don't use call-clobbered registers across a call which clobbers it. On - some machines, don't use any hard registers at all. */ - if (REGNO (x) < FIRST_PSEUDO_REGISTER - && (SMALL_REGISTER_CLASSES - || (call_used_regs[REGNO (x)] && call_seen))) - return 0; - - /* Don't use registers that have been clobbered before the start of the - loop. */ - if (reg_set_between_p (x, insn, loop_start)) - return 0; - - return 1; -} - -/* Scan X for memory refs and check each memory address - as a possible giv. INSN is the insn whose pattern X comes from. - NOT_EVERY_ITERATION is 1 if the insn might not be executed during - every loop iteration. MAYBE_MULTIPLE is 1 if the insn might be executed - more than once in each loop iteration. */ - -static void -find_mem_givs (const struct loop *loop, rtx x, rtx insn, - int not_every_iteration, int maybe_multiple) -{ - int i, j; - enum rtx_code code; - const char *fmt; - - if (x == 0) - return; - - code = GET_CODE (x); - switch (code) - { - case REG: - case CONST_INT: - case CONST: - case CONST_DOUBLE: - case SYMBOL_REF: - case LABEL_REF: - case PC: - case CC0: - case ADDR_VEC: - case ADDR_DIFF_VEC: - case USE: - case CLOBBER: - return; - - case MEM: - { - rtx src_reg; - rtx add_val; - rtx mult_val; - rtx ext_val; - int benefit; - - /* This code used to disable creating GIVs with mult_val == 1 and - add_val == 0. However, this leads to lost optimizations when - it comes time to combine a set of related DEST_ADDR GIVs, since - this one would not be seen. */ - - if (general_induction_var (loop, XEXP (x, 0), &src_reg, &add_val, - &mult_val, &ext_val, 1, &benefit, - GET_MODE (x))) - { - /* Found one; record it. */ - struct induction *v = xmalloc (sizeof (struct induction)); - - record_giv (loop, v, insn, src_reg, addr_placeholder, mult_val, - add_val, ext_val, benefit, DEST_ADDR, - not_every_iteration, maybe_multiple, &XEXP (x, 0)); - - v->mem = x; - } - } - return; - - default: - break; - } - - /* Recursively scan the subexpressions for other mem refs. */ - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - if (fmt[i] == 'e') - find_mem_givs (loop, XEXP (x, i), insn, not_every_iteration, - maybe_multiple); - else if (fmt[i] == 'E') - for (j = 0; j < XVECLEN (x, i); j++) - find_mem_givs (loop, XVECEXP (x, i, j), insn, not_every_iteration, - maybe_multiple); -} - -/* Fill in the data about one biv update. - V is the `struct induction' in which we record the biv. (It is - allocated by the caller, with alloca.) - INSN is the insn that sets it. - DEST_REG is the biv's reg. - - MULT_VAL is const1_rtx if the biv is being incremented here, in which case - INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is - being set to INC_VAL. - - NOT_EVERY_ITERATION is nonzero if this biv update is not know to be - executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update - can be executed more than once per iteration. If MAYBE_MULTIPLE - and NOT_EVERY_ITERATION are both zero, we know that the biv update is - executed exactly once per iteration. */ - -static void -record_biv (struct loop *loop, struct induction *v, rtx insn, rtx dest_reg, - rtx inc_val, rtx mult_val, rtx *location, - int not_every_iteration, int maybe_multiple) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - - v->insn = insn; - v->src_reg = dest_reg; - v->dest_reg = dest_reg; - v->mult_val = mult_val; - v->add_val = inc_val; - v->ext_dependent = NULL_RTX; - v->location = location; - v->mode = GET_MODE (dest_reg); - v->always_computable = ! not_every_iteration; - v->always_executed = ! not_every_iteration; - v->maybe_multiple = maybe_multiple; - v->same = 0; - - /* Add this to the reg's iv_class, creating a class - if this is the first incrementation of the reg. */ - - bl = REG_IV_CLASS (ivs, REGNO (dest_reg)); - if (bl == 0) - { - /* Create and initialize new iv_class. */ - - bl = xmalloc (sizeof (struct iv_class)); - - bl->regno = REGNO (dest_reg); - bl->biv = 0; - bl->giv = 0; - bl->biv_count = 0; - bl->giv_count = 0; - - /* Set initial value to the reg itself. */ - bl->initial_value = dest_reg; - bl->final_value = 0; - /* We haven't seen the initializing insn yet. */ - bl->init_insn = 0; - bl->init_set = 0; - bl->initial_test = 0; - bl->incremented = 0; - bl->eliminable = 0; - bl->nonneg = 0; - bl->reversed = 0; - bl->total_benefit = 0; - - /* Add this class to ivs->list. */ - bl->next = ivs->list; - ivs->list = bl; - - /* Put it in the array of biv register classes. */ - REG_IV_CLASS (ivs, REGNO (dest_reg)) = bl; - } - else - { - /* Check if location is the same as a previous one. */ - struct induction *induction; - for (induction = bl->biv; induction; induction = induction->next_iv) - if (location == induction->location) - { - v->same = induction; - break; - } - } - - /* Update IV_CLASS entry for this biv. */ - v->next_iv = bl->biv; - bl->biv = v; - bl->biv_count++; - if (mult_val == const1_rtx) - bl->incremented = 1; - - if (loop_dump_stream) - loop_biv_dump (v, loop_dump_stream, 0); -} - -/* Fill in the data about one giv. - V is the `struct induction' in which we record the giv. (It is - allocated by the caller, with alloca.) - INSN is the insn that sets it. - BENEFIT estimates the savings from deleting this insn. - TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed - into a register or is used as a memory address. - - SRC_REG is the biv reg which the giv is computed from. - DEST_REG is the giv's reg (if the giv is stored in a reg). - MULT_VAL and ADD_VAL are the coefficients used to compute the giv. - LOCATION points to the place where this giv's value appears in INSN. */ - -static void -record_giv (const struct loop *loop, struct induction *v, rtx insn, - rtx src_reg, rtx dest_reg, rtx mult_val, rtx add_val, - rtx ext_val, int benefit, enum g_types type, - int not_every_iteration, int maybe_multiple, rtx *location) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct induction *b; - struct iv_class *bl; - rtx set = single_set (insn); - rtx temp; - - /* Attempt to prove constantness of the values. Don't let simplify_rtx - undo the MULT canonicalization that we performed earlier. */ - temp = simplify_rtx (add_val); - if (temp - && ! (GET_CODE (add_val) == MULT - && GET_CODE (temp) == ASHIFT)) - add_val = temp; - - v->insn = insn; - v->src_reg = src_reg; - v->giv_type = type; - v->dest_reg = dest_reg; - v->mult_val = mult_val; - v->add_val = add_val; - v->ext_dependent = ext_val; - v->benefit = benefit; - v->location = location; - v->cant_derive = 0; - v->combined_with = 0; - v->maybe_multiple = maybe_multiple; - v->maybe_dead = 0; - v->derive_adjustment = 0; - v->same = 0; - v->ignore = 0; - v->new_reg = 0; - v->final_value = 0; - v->same_insn = 0; - v->auto_inc_opt = 0; - v->unrolled = 0; - v->shared = 0; - - /* The v->always_computable field is used in update_giv_derive, to - determine whether a giv can be used to derive another giv. For a - DEST_REG giv, INSN computes a new value for the giv, so its value - isn't computable if INSN insn't executed every iteration. - However, for a DEST_ADDR giv, INSN merely uses the value of the giv; - it does not compute a new value. Hence the value is always computable - regardless of whether INSN is executed each iteration. */ - - if (type == DEST_ADDR) - v->always_computable = 1; - else - v->always_computable = ! not_every_iteration; - - v->always_executed = ! not_every_iteration; - - if (type == DEST_ADDR) - { - v->mode = GET_MODE (*location); - v->lifetime = 1; - } - else /* type == DEST_REG */ - { - v->mode = GET_MODE (SET_DEST (set)); - - v->lifetime = LOOP_REG_LIFETIME (loop, REGNO (dest_reg)); - - /* If the lifetime is zero, it means that this register is - really a dead store. So mark this as a giv that can be - ignored. This will not prevent the biv from being eliminated. */ - if (v->lifetime == 0) - v->ignore = 1; - - REG_IV_TYPE (ivs, REGNO (dest_reg)) = GENERAL_INDUCT; - REG_IV_INFO (ivs, REGNO (dest_reg)) = v; - } - - /* Add the giv to the class of givs computed from one biv. */ - - bl = REG_IV_CLASS (ivs, REGNO (src_reg)); - if (bl) - { - v->next_iv = bl->giv; - bl->giv = v; - /* Don't count DEST_ADDR. This is supposed to count the number of - insns that calculate givs. */ - if (type == DEST_REG) - bl->giv_count++; - bl->total_benefit += benefit; - } - else - /* Fatal error, biv missing for this giv? */ - abort (); - - if (type == DEST_ADDR) - { - v->replaceable = 1; - v->not_replaceable = 0; - } - else - { - /* The giv can be replaced outright by the reduced register only if all - of the following conditions are true: - - the insn that sets the giv is always executed on any iteration - on which the giv is used at all - (there are two ways to deduce this: - either the insn is executed on every iteration, - or all uses follow that insn in the same basic block), - - the giv is not used outside the loop - - no assignments to the biv occur during the giv's lifetime. */ - - if (REGNO_FIRST_UID (REGNO (dest_reg)) == INSN_UID (insn) - /* Previous line always fails if INSN was moved by loop opt. */ - && REGNO_LAST_LUID (REGNO (dest_reg)) - < INSN_LUID (loop->end) - && (! not_every_iteration - || last_use_this_basic_block (dest_reg, insn))) - { - /* Now check that there are no assignments to the biv within the - giv's lifetime. This requires two separate checks. */ - - /* Check each biv update, and fail if any are between the first - and last use of the giv. - - If this loop contains an inner loop that was unrolled, then - the insn modifying the biv may have been emitted by the loop - unrolling code, and hence does not have a valid luid. Just - mark the biv as not replaceable in this case. It is not very - useful as a biv, because it is used in two different loops. - It is very unlikely that we would be able to optimize the giv - using this biv anyways. */ - - v->replaceable = 1; - v->not_replaceable = 0; - for (b = bl->biv; b; b = b->next_iv) - { - if (INSN_UID (b->insn) >= max_uid_for_loop - || ((INSN_LUID (b->insn) - >= REGNO_FIRST_LUID (REGNO (dest_reg))) - && (INSN_LUID (b->insn) - <= REGNO_LAST_LUID (REGNO (dest_reg))))) - { - v->replaceable = 0; - v->not_replaceable = 1; - break; - } - } - - /* If there are any backwards branches that go from after the - biv update to before it, then this giv is not replaceable. */ - if (v->replaceable) - for (b = bl->biv; b; b = b->next_iv) - if (back_branch_in_range_p (loop, b->insn)) - { - v->replaceable = 0; - v->not_replaceable = 1; - break; - } - } - else - { - /* May still be replaceable, we don't have enough info here to - decide. */ - v->replaceable = 0; - v->not_replaceable = 0; - } - } - - /* Record whether the add_val contains a const_int, for later use by - combine_givs. */ - { - rtx tem = add_val; - - v->no_const_addval = 1; - if (tem == const0_rtx) - ; - else if (CONSTANT_P (add_val)) - v->no_const_addval = 0; - if (GET_CODE (tem) == PLUS) - { - while (1) - { - if (GET_CODE (XEXP (tem, 0)) == PLUS) - tem = XEXP (tem, 0); - else if (GET_CODE (XEXP (tem, 1)) == PLUS) - tem = XEXP (tem, 1); - else - break; - } - if (CONSTANT_P (XEXP (tem, 1))) - v->no_const_addval = 0; - } - } - - if (loop_dump_stream) - loop_giv_dump (v, loop_dump_stream, 0); -} - -/* All this does is determine whether a giv can be made replaceable because - its final value can be calculated. This code can not be part of record_giv - above, because final_giv_value requires that the number of loop iterations - be known, and that can not be accurately calculated until after all givs - have been identified. */ - -static void -check_final_value (const struct loop *loop, struct induction *v) -{ - rtx final_value = 0; - - /* DEST_ADDR givs will never reach here, because they are always marked - replaceable above in record_giv. */ - - /* The giv can be replaced outright by the reduced register only if all - of the following conditions are true: - - the insn that sets the giv is always executed on any iteration - on which the giv is used at all - (there are two ways to deduce this: - either the insn is executed on every iteration, - or all uses follow that insn in the same basic block), - - its final value can be calculated (this condition is different - than the one above in record_giv) - - it's not used before the it's set - - no assignments to the biv occur during the giv's lifetime. */ - -#if 0 - /* This is only called now when replaceable is known to be false. */ - /* Clear replaceable, so that it won't confuse final_giv_value. */ - v->replaceable = 0; -#endif - - if ((final_value = final_giv_value (loop, v)) - && (v->always_executed - || last_use_this_basic_block (v->dest_reg, v->insn))) - { - int biv_increment_seen = 0, before_giv_insn = 0; - rtx p = v->insn; - rtx last_giv_use; - - v->replaceable = 1; - v->not_replaceable = 0; - - /* When trying to determine whether or not a biv increment occurs - during the lifetime of the giv, we can ignore uses of the variable - outside the loop because final_value is true. Hence we can not - use regno_last_uid and regno_first_uid as above in record_giv. */ - - /* Search the loop to determine whether any assignments to the - biv occur during the giv's lifetime. Start with the insn - that sets the giv, and search around the loop until we come - back to that insn again. - - Also fail if there is a jump within the giv's lifetime that jumps - to somewhere outside the lifetime but still within the loop. This - catches spaghetti code where the execution order is not linear, and - hence the above test fails. Here we assume that the giv lifetime - does not extend from one iteration of the loop to the next, so as - to make the test easier. Since the lifetime isn't known yet, - this requires two loops. See also record_giv above. */ - - last_giv_use = v->insn; - - while (1) - { - p = NEXT_INSN (p); - if (p == loop->end) - { - before_giv_insn = 1; - p = NEXT_INSN (loop->start); - } - if (p == v->insn) - break; - - if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN - || GET_CODE (p) == CALL_INSN) - { - /* It is possible for the BIV increment to use the GIV if we - have a cycle. Thus we must be sure to check each insn for - both BIV and GIV uses, and we must check for BIV uses - first. */ - - if (! biv_increment_seen - && reg_set_p (v->src_reg, PATTERN (p))) - biv_increment_seen = 1; - - if (reg_mentioned_p (v->dest_reg, PATTERN (p))) - { - if (biv_increment_seen || before_giv_insn) - { - v->replaceable = 0; - v->not_replaceable = 1; - break; - } - last_giv_use = p; - } - } - } - - /* Now that the lifetime of the giv is known, check for branches - from within the lifetime to outside the lifetime if it is still - replaceable. */ - - if (v->replaceable) - { - p = v->insn; - while (1) - { - p = NEXT_INSN (p); - if (p == loop->end) - p = NEXT_INSN (loop->start); - if (p == last_giv_use) - break; - - if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) - && LABEL_NAME (JUMP_LABEL (p)) - && ((loop_insn_first_p (JUMP_LABEL (p), v->insn) - && loop_insn_first_p (loop->start, JUMP_LABEL (p))) - || (loop_insn_first_p (last_giv_use, JUMP_LABEL (p)) - && loop_insn_first_p (JUMP_LABEL (p), loop->end)))) - { - v->replaceable = 0; - v->not_replaceable = 1; - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Found branch outside giv lifetime.\n"); - - break; - } - } - } - - /* If it is replaceable, then save the final value. */ - if (v->replaceable) - v->final_value = final_value; - } - - if (loop_dump_stream && v->replaceable) - fprintf (loop_dump_stream, "Insn %d: giv reg %d final_value replaceable\n", - INSN_UID (v->insn), REGNO (v->dest_reg)); -} - -/* Update the status of whether a giv can derive other givs. - - We need to do something special if there is or may be an update to the biv - between the time the giv is defined and the time it is used to derive - another giv. - - In addition, a giv that is only conditionally set is not allowed to - derive another giv once a label has been passed. - - The cases we look at are when a label or an update to a biv is passed. */ - -static void -update_giv_derive (const struct loop *loop, rtx p) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - struct induction *biv, *giv; - rtx tem; - int dummy; - - /* Search all IV classes, then all bivs, and finally all givs. - - There are three cases we are concerned with. First we have the situation - of a giv that is only updated conditionally. In that case, it may not - derive any givs after a label is passed. - - The second case is when a biv update occurs, or may occur, after the - definition of a giv. For certain biv updates (see below) that are - known to occur between the giv definition and use, we can adjust the - giv definition. For others, or when the biv update is conditional, - we must prevent the giv from deriving any other givs. There are two - sub-cases within this case. - - If this is a label, we are concerned with any biv update that is done - conditionally, since it may be done after the giv is defined followed by - a branch here (actually, we need to pass both a jump and a label, but - this extra tracking doesn't seem worth it). - - If this is a jump, we are concerned about any biv update that may be - executed multiple times. We are actually only concerned about - backward jumps, but it is probably not worth performing the test - on the jump again here. - - If this is a biv update, we must adjust the giv status to show that a - subsequent biv update was performed. If this adjustment cannot be done, - the giv cannot derive further givs. */ - - for (bl = ivs->list; bl; bl = bl->next) - for (biv = bl->biv; biv; biv = biv->next_iv) - if (GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN - || biv->insn == p) - { - /* Skip if location is the same as a previous one. */ - if (biv->same) - continue; - - for (giv = bl->giv; giv; giv = giv->next_iv) - { - /* If cant_derive is already true, there is no point in - checking all of these conditions again. */ - if (giv->cant_derive) - continue; - - /* If this giv is conditionally set and we have passed a label, - it cannot derive anything. */ - if (GET_CODE (p) == CODE_LABEL && ! giv->always_computable) - giv->cant_derive = 1; - - /* Skip givs that have mult_val == 0, since - they are really invariants. Also skip those that are - replaceable, since we know their lifetime doesn't contain - any biv update. */ - else if (giv->mult_val == const0_rtx || giv->replaceable) - continue; - - /* The only way we can allow this giv to derive another - is if this is a biv increment and we can form the product - of biv->add_val and giv->mult_val. In this case, we will - be able to compute a compensation. */ - else if (biv->insn == p) - { - rtx ext_val_dummy; - - tem = 0; - if (biv->mult_val == const1_rtx) - tem = simplify_giv_expr (loop, - gen_rtx_MULT (giv->mode, - biv->add_val, - giv->mult_val), - &ext_val_dummy, &dummy); - - if (tem && giv->derive_adjustment) - tem = simplify_giv_expr - (loop, - gen_rtx_PLUS (giv->mode, tem, giv->derive_adjustment), - &ext_val_dummy, &dummy); - - if (tem) - giv->derive_adjustment = tem; - else - giv->cant_derive = 1; - } - else if ((GET_CODE (p) == CODE_LABEL && ! biv->always_computable) - || (GET_CODE (p) == JUMP_INSN && biv->maybe_multiple)) - giv->cant_derive = 1; - } - } -} - -/* Check whether an insn is an increment legitimate for a basic induction var. - X is the source of insn P, or a part of it. - MODE is the mode in which X should be interpreted. - - DEST_REG is the putative biv, also the destination of the insn. - We accept patterns of these forms: - REG = REG + INVARIANT (includes REG = REG - CONSTANT) - REG = INVARIANT + REG - - If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX, - store the additive term into *INC_VAL, and store the place where - we found the additive term into *LOCATION. - - If X is an assignment of an invariant into DEST_REG, we set - *MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL. - - We also want to detect a BIV when it corresponds to a variable - whose mode was promoted. In that case, an increment - of the variable may be a PLUS that adds a SUBREG of that variable to - an invariant and then sign- or zero-extends the result of the PLUS - into the variable. - - Most GIVs in such cases will be in the promoted mode, since that is the - probably the natural computation mode (and almost certainly the mode - used for addresses) on the machine. So we view the pseudo-reg containing - the variable as the BIV, as if it were simply incremented. - - Note that treating the entire pseudo as a BIV will result in making - simple increments to any GIVs based on it. However, if the variable - overflows in its declared mode but not its promoted mode, the result will - be incorrect. This is acceptable if the variable is signed, since - overflows in such cases are undefined, but not if it is unsigned, since - those overflows are defined. So we only check for SIGN_EXTEND and - not ZERO_EXTEND. - - If we cannot find a biv, we return 0. */ - -static int -basic_induction_var (const struct loop *loop, rtx x, enum machine_mode mode, - rtx dest_reg, rtx p, rtx *inc_val, rtx *mult_val, - rtx **location) -{ - enum rtx_code code; - rtx *argp, arg; - rtx insn, set = 0, last, inc; - - code = GET_CODE (x); - *location = NULL; - switch (code) - { - case PLUS: - if (rtx_equal_p (XEXP (x, 0), dest_reg) - || (GET_CODE (XEXP (x, 0)) == SUBREG - && SUBREG_PROMOTED_VAR_P (XEXP (x, 0)) - && SUBREG_REG (XEXP (x, 0)) == dest_reg)) - { - argp = &XEXP (x, 1); - } - else if (rtx_equal_p (XEXP (x, 1), dest_reg) - || (GET_CODE (XEXP (x, 1)) == SUBREG - && SUBREG_PROMOTED_VAR_P (XEXP (x, 1)) - && SUBREG_REG (XEXP (x, 1)) == dest_reg)) - { - argp = &XEXP (x, 0); - } - else - return 0; - - arg = *argp; - if (loop_invariant_p (loop, arg) != 1) - return 0; - - /* convert_modes can emit new instructions, e.g. when arg is a loop - invariant MEM and dest_reg has a different mode. - These instructions would be emitted after the end of the function - and then *inc_val would be an uninitialized pseudo. - Detect this and bail in this case. - Other alternatives to solve this can be introducing a convert_modes - variant which is allowed to fail but not allowed to emit new - instructions, emit these instructions before loop start and let - it be garbage collected if *inc_val is never used or saving the - *inc_val initialization sequence generated here and when *inc_val - is going to be actually used, emit it at some suitable place. */ - last = get_last_insn (); - inc = convert_modes (GET_MODE (dest_reg), GET_MODE (x), arg, 0); - if (get_last_insn () != last) - { - delete_insns_since (last); - return 0; - } - - *inc_val = inc; - *mult_val = const1_rtx; - *location = argp; - return 1; - - case SUBREG: - /* If what's inside the SUBREG is a BIV, then the SUBREG. This will - handle addition of promoted variables. - ??? The comment at the start of this function is wrong: promoted - variable increments don't look like it says they do. */ - return basic_induction_var (loop, SUBREG_REG (x), - GET_MODE (SUBREG_REG (x)), - dest_reg, p, inc_val, mult_val, location); - - case REG: - /* If this register is assigned in a previous insn, look at its - source, but don't go outside the loop or past a label. */ - - /* If this sets a register to itself, we would repeat any previous - biv increment if we applied this strategy blindly. */ - if (rtx_equal_p (dest_reg, x)) - return 0; - - insn = p; - while (1) - { - rtx dest; - do - { - insn = PREV_INSN (insn); - } - while (insn && GET_CODE (insn) == NOTE - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); - - if (!insn) - break; - set = single_set (insn); - if (set == 0) - break; - dest = SET_DEST (set); - if (dest == x - || (GET_CODE (dest) == SUBREG - && (GET_MODE_SIZE (GET_MODE (dest)) <= UNITS_PER_WORD) - && (GET_MODE_CLASS (GET_MODE (dest)) == MODE_INT) - && SUBREG_REG (dest) == x)) - return basic_induction_var (loop, SET_SRC (set), - (GET_MODE (SET_SRC (set)) == VOIDmode - ? GET_MODE (x) - : GET_MODE (SET_SRC (set))), - dest_reg, insn, - inc_val, mult_val, location); - - while (GET_CODE (dest) == SIGN_EXTRACT - || GET_CODE (dest) == ZERO_EXTRACT - || GET_CODE (dest) == SUBREG - || GET_CODE (dest) == STRICT_LOW_PART) - dest = XEXP (dest, 0); - if (dest == x) - break; - } - /* Fall through. */ - - /* Can accept constant setting of biv only when inside inner most loop. - Otherwise, a biv of an inner loop may be incorrectly recognized - as a biv of the outer loop, - causing code to be moved INTO the inner loop. */ - case MEM: - if (loop_invariant_p (loop, x) != 1) - return 0; - case CONST_INT: - case SYMBOL_REF: - case CONST: - /* convert_modes aborts if we try to convert to or from CCmode, so just - exclude that case. It is very unlikely that a condition code value - would be a useful iterator anyways. convert_modes aborts if we try to - convert a float mode to non-float or vice versa too. */ - if (loop->level == 1 - && GET_MODE_CLASS (mode) == GET_MODE_CLASS (GET_MODE (dest_reg)) - && GET_MODE_CLASS (mode) != MODE_CC) - { - /* Possible bug here? Perhaps we don't know the mode of X. */ - last = get_last_insn (); - inc = convert_modes (GET_MODE (dest_reg), mode, x, 0); - if (get_last_insn () != last) - { - delete_insns_since (last); - return 0; - } - - *inc_val = inc; - *mult_val = const0_rtx; - return 1; - } - else - return 0; - - case SIGN_EXTEND: - /* Ignore this BIV if signed arithmetic overflow is defined. */ - if (flag_wrapv) - return 0; - return basic_induction_var (loop, XEXP (x, 0), GET_MODE (XEXP (x, 0)), - dest_reg, p, inc_val, mult_val, location); - - case ASHIFTRT: - /* Similar, since this can be a sign extension. */ - for (insn = PREV_INSN (p); - (insn && GET_CODE (insn) == NOTE - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); - insn = PREV_INSN (insn)) - ; - - if (insn) - set = single_set (insn); - - if (! rtx_equal_p (dest_reg, XEXP (x, 0)) - && set && SET_DEST (set) == XEXP (x, 0) - && GET_CODE (XEXP (x, 1)) == CONST_INT - && INTVAL (XEXP (x, 1)) >= 0 - && GET_CODE (SET_SRC (set)) == ASHIFT - && XEXP (x, 1) == XEXP (SET_SRC (set), 1)) - return basic_induction_var (loop, XEXP (SET_SRC (set), 0), - GET_MODE (XEXP (x, 0)), - dest_reg, insn, inc_val, mult_val, - location); - return 0; - - default: - return 0; - } -} - -/* A general induction variable (giv) is any quantity that is a linear - function of a basic induction variable, - i.e. giv = biv * mult_val + add_val. - The coefficients can be any loop invariant quantity. - A giv need not be computed directly from the biv; - it can be computed by way of other givs. */ - -/* Determine whether X computes a giv. - If it does, return a nonzero value - which is the benefit from eliminating the computation of X; - set *SRC_REG to the register of the biv that it is computed from; - set *ADD_VAL and *MULT_VAL to the coefficients, - such that the value of X is biv * mult + add; */ - -static int -general_induction_var (const struct loop *loop, rtx x, rtx *src_reg, - rtx *add_val, rtx *mult_val, rtx *ext_val, - int is_addr, int *pbenefit, - enum machine_mode addr_mode) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx orig_x = x; - - /* If this is an invariant, forget it, it isn't a giv. */ - if (loop_invariant_p (loop, x) == 1) - return 0; - - *pbenefit = 0; - *ext_val = NULL_RTX; - x = simplify_giv_expr (loop, x, ext_val, pbenefit); - if (x == 0) - return 0; - - switch (GET_CODE (x)) - { - case USE: - case CONST_INT: - /* Since this is now an invariant and wasn't before, it must be a giv - with MULT_VAL == 0. It doesn't matter which BIV we associate this - with. */ - *src_reg = ivs->list->biv->dest_reg; - *mult_val = const0_rtx; - *add_val = x; - break; - - case REG: - /* This is equivalent to a BIV. */ - *src_reg = x; - *mult_val = const1_rtx; - *add_val = const0_rtx; - break; - - case PLUS: - /* Either (plus (biv) (invar)) or - (plus (mult (biv) (invar_1)) (invar_2)). */ - if (GET_CODE (XEXP (x, 0)) == MULT) - { - *src_reg = XEXP (XEXP (x, 0), 0); - *mult_val = XEXP (XEXP (x, 0), 1); - } - else - { - *src_reg = XEXP (x, 0); - *mult_val = const1_rtx; - } - *add_val = XEXP (x, 1); - break; - - case MULT: - /* ADD_VAL is zero. */ - *src_reg = XEXP (x, 0); - *mult_val = XEXP (x, 1); - *add_val = const0_rtx; - break; - - default: - abort (); - } - - /* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be - unless they are CONST_INT). */ - if (GET_CODE (*add_val) == USE) - *add_val = XEXP (*add_val, 0); - if (GET_CODE (*mult_val) == USE) - *mult_val = XEXP (*mult_val, 0); - - if (is_addr) - *pbenefit += address_cost (orig_x, addr_mode) - reg_address_cost; - else - *pbenefit += rtx_cost (orig_x, SET); - - /* Always return true if this is a giv so it will be detected as such, - even if the benefit is zero or negative. This allows elimination - of bivs that might otherwise not be eliminated. */ - return 1; -} - -/* Given an expression, X, try to form it as a linear function of a biv. - We will canonicalize it to be of the form - (plus (mult (BIV) (invar_1)) - (invar_2)) - with possible degeneracies. - - The invariant expressions must each be of a form that can be used as a - machine operand. We surround then with a USE rtx (a hack, but localized - and certainly unambiguous!) if not a CONST_INT for simplicity in this - routine; it is the caller's responsibility to strip them. - - If no such canonicalization is possible (i.e., two biv's are used or an - expression that is neither invariant nor a biv or giv), this routine - returns 0. - - For a nonzero return, the result will have a code of CONST_INT, USE, - REG (for a BIV), PLUS, or MULT. No other codes will occur. - - *BENEFIT will be incremented by the benefit of any sub-giv encountered. */ - -static rtx sge_plus (enum machine_mode, rtx, rtx); -static rtx sge_plus_constant (rtx, rtx); - -static rtx -simplify_giv_expr (const struct loop *loop, rtx x, rtx *ext_val, int *benefit) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct loop_regs *regs = LOOP_REGS (loop); - enum machine_mode mode = GET_MODE (x); - rtx arg0, arg1; - rtx tem; - - /* If this is not an integer mode, or if we cannot do arithmetic in this - mode, this can't be a giv. */ - if (mode != VOIDmode - && (GET_MODE_CLASS (mode) != MODE_INT - || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT)) - return NULL_RTX; - - switch (GET_CODE (x)) - { - case PLUS: - arg0 = simplify_giv_expr (loop, XEXP (x, 0), ext_val, benefit); - arg1 = simplify_giv_expr (loop, XEXP (x, 1), ext_val, benefit); - if (arg0 == 0 || arg1 == 0) - return NULL_RTX; - - /* Put constant last, CONST_INT last if both constant. */ - if ((GET_CODE (arg0) == USE - || GET_CODE (arg0) == CONST_INT) - && ! ((GET_CODE (arg0) == USE - && GET_CODE (arg1) == USE) - || GET_CODE (arg1) == CONST_INT)) - tem = arg0, arg0 = arg1, arg1 = tem; - - /* Handle addition of zero, then addition of an invariant. */ - if (arg1 == const0_rtx) - return arg0; - else if (GET_CODE (arg1) == CONST_INT || GET_CODE (arg1) == USE) - switch (GET_CODE (arg0)) - { - case CONST_INT: - case USE: - /* Adding two invariants must result in an invariant, so enclose - addition operation inside a USE and return it. */ - if (GET_CODE (arg0) == USE) - arg0 = XEXP (arg0, 0); - if (GET_CODE (arg1) == USE) - arg1 = XEXP (arg1, 0); - - if (GET_CODE (arg0) == CONST_INT) - tem = arg0, arg0 = arg1, arg1 = tem; - if (GET_CODE (arg1) == CONST_INT) - tem = sge_plus_constant (arg0, arg1); - else - tem = sge_plus (mode, arg0, arg1); - - if (GET_CODE (tem) != CONST_INT) - tem = gen_rtx_USE (mode, tem); - return tem; - - case REG: - case MULT: - /* biv + invar or mult + invar. Return sum. */ - return gen_rtx_PLUS (mode, arg0, arg1); - - case PLUS: - /* (a + invar_1) + invar_2. Associate. */ - return - simplify_giv_expr (loop, - gen_rtx_PLUS (mode, - XEXP (arg0, 0), - gen_rtx_PLUS (mode, - XEXP (arg0, 1), - arg1)), - ext_val, benefit); - - default: - abort (); - } - - /* Each argument must be either REG, PLUS, or MULT. Convert REG to - MULT to reduce cases. */ - if (GET_CODE (arg0) == REG) - arg0 = gen_rtx_MULT (mode, arg0, const1_rtx); - if (GET_CODE (arg1) == REG) - arg1 = gen_rtx_MULT (mode, arg1, const1_rtx); - - /* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT. - Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT. - Recurse to associate the second PLUS. */ - if (GET_CODE (arg1) == MULT) - tem = arg0, arg0 = arg1, arg1 = tem; - - if (GET_CODE (arg1) == PLUS) - return - simplify_giv_expr (loop, - gen_rtx_PLUS (mode, - gen_rtx_PLUS (mode, arg0, - XEXP (arg1, 0)), - XEXP (arg1, 1)), - ext_val, benefit); - - /* Now must have MULT + MULT. Distribute if same biv, else not giv. */ - if (GET_CODE (arg0) != MULT || GET_CODE (arg1) != MULT) - return NULL_RTX; - - if (!rtx_equal_p (arg0, arg1)) - return NULL_RTX; - - return simplify_giv_expr (loop, - gen_rtx_MULT (mode, - XEXP (arg0, 0), - gen_rtx_PLUS (mode, - XEXP (arg0, 1), - XEXP (arg1, 1))), - ext_val, benefit); - - case MINUS: - /* Handle "a - b" as "a + b * (-1)". */ - return simplify_giv_expr (loop, - gen_rtx_PLUS (mode, - XEXP (x, 0), - gen_rtx_MULT (mode, - XEXP (x, 1), - constm1_rtx)), - ext_val, benefit); - - case MULT: - arg0 = simplify_giv_expr (loop, XEXP (x, 0), ext_val, benefit); - arg1 = simplify_giv_expr (loop, XEXP (x, 1), ext_val, benefit); - if (arg0 == 0 || arg1 == 0) - return NULL_RTX; - - /* Put constant last, CONST_INT last if both constant. */ - if ((GET_CODE (arg0) == USE || GET_CODE (arg0) == CONST_INT) - && GET_CODE (arg1) != CONST_INT) - tem = arg0, arg0 = arg1, arg1 = tem; - - /* If second argument is not now constant, not giv. */ - if (GET_CODE (arg1) != USE && GET_CODE (arg1) != CONST_INT) - return NULL_RTX; - - /* Handle multiply by 0 or 1. */ - if (arg1 == const0_rtx) - return const0_rtx; - - else if (arg1 == const1_rtx) - return arg0; - - switch (GET_CODE (arg0)) - { - case REG: - /* biv * invar. Done. */ - return gen_rtx_MULT (mode, arg0, arg1); - - case CONST_INT: - /* Product of two constants. */ - return GEN_INT (INTVAL (arg0) * INTVAL (arg1)); - - case USE: - /* invar * invar is a giv, but attempt to simplify it somehow. */ - if (GET_CODE (arg1) != CONST_INT) - return NULL_RTX; - - arg0 = XEXP (arg0, 0); - if (GET_CODE (arg0) == MULT) - { - /* (invar_0 * invar_1) * invar_2. Associate. */ - return simplify_giv_expr (loop, - gen_rtx_MULT (mode, - XEXP (arg0, 0), - gen_rtx_MULT (mode, - XEXP (arg0, - 1), - arg1)), - ext_val, benefit); - } - /* Propagate the MULT expressions to the innermost nodes. */ - else if (GET_CODE (arg0) == PLUS) - { - /* (invar_0 + invar_1) * invar_2. Distribute. */ - return simplify_giv_expr (loop, - gen_rtx_PLUS (mode, - gen_rtx_MULT (mode, - XEXP (arg0, - 0), - arg1), - gen_rtx_MULT (mode, - XEXP (arg0, - 1), - arg1)), - ext_val, benefit); - } - return gen_rtx_USE (mode, gen_rtx_MULT (mode, arg0, arg1)); - - case MULT: - /* (a * invar_1) * invar_2. Associate. */ - return simplify_giv_expr (loop, - gen_rtx_MULT (mode, - XEXP (arg0, 0), - gen_rtx_MULT (mode, - XEXP (arg0, 1), - arg1)), - ext_val, benefit); - - case PLUS: - /* (a + invar_1) * invar_2. Distribute. */ - return simplify_giv_expr (loop, - gen_rtx_PLUS (mode, - gen_rtx_MULT (mode, - XEXP (arg0, 0), - arg1), - gen_rtx_MULT (mode, - XEXP (arg0, 1), - arg1)), - ext_val, benefit); - - default: - abort (); - } - - case ASHIFT: - /* Shift by constant is multiply by power of two. */ - if (GET_CODE (XEXP (x, 1)) != CONST_INT) - return 0; - - return - simplify_giv_expr (loop, - gen_rtx_MULT (mode, - XEXP (x, 0), - GEN_INT ((HOST_WIDE_INT) 1 - << INTVAL (XEXP (x, 1)))), - ext_val, benefit); - - case NEG: - /* "-a" is "a * (-1)" */ - return simplify_giv_expr (loop, - gen_rtx_MULT (mode, XEXP (x, 0), constm1_rtx), - ext_val, benefit); - - case NOT: - /* "~a" is "-a - 1". Silly, but easy. */ - return simplify_giv_expr (loop, - gen_rtx_MINUS (mode, - gen_rtx_NEG (mode, XEXP (x, 0)), - const1_rtx), - ext_val, benefit); - - case USE: - /* Already in proper form for invariant. */ - return x; - - case SIGN_EXTEND: - case ZERO_EXTEND: - case TRUNCATE: - /* Conditionally recognize extensions of simple IVs. After we've - computed loop traversal counts and verified the range of the - source IV, we'll reevaluate this as a GIV. */ - if (*ext_val == NULL_RTX) - { - arg0 = simplify_giv_expr (loop, XEXP (x, 0), ext_val, benefit); - if (arg0 && *ext_val == NULL_RTX && GET_CODE (arg0) == REG) - { - *ext_val = gen_rtx_fmt_e (GET_CODE (x), mode, arg0); - return arg0; - } - } - goto do_default; - - case REG: - /* If this is a new register, we can't deal with it. */ - if (REGNO (x) >= max_reg_before_loop) - return 0; - - /* Check for biv or giv. */ - switch (REG_IV_TYPE (ivs, REGNO (x))) - { - case BASIC_INDUCT: - return x; - case GENERAL_INDUCT: - { - struct induction *v = REG_IV_INFO (ivs, REGNO (x)); - - /* Form expression from giv and add benefit. Ensure this giv - can derive another and subtract any needed adjustment if so. */ - - /* Increasing the benefit here is risky. The only case in which it - is arguably correct is if this is the only use of V. In other - cases, this will artificially inflate the benefit of the current - giv, and lead to suboptimal code. Thus, it is disabled, since - potentially not reducing an only marginally beneficial giv is - less harmful than reducing many givs that are not really - beneficial. */ - { - rtx single_use = regs->array[REGNO (x)].single_usage; - if (single_use && single_use != const0_rtx) - *benefit += v->benefit; - } - - if (v->cant_derive) - return 0; - - tem = gen_rtx_PLUS (mode, gen_rtx_MULT (mode, - v->src_reg, v->mult_val), - v->add_val); - - if (v->derive_adjustment) - tem = gen_rtx_MINUS (mode, tem, v->derive_adjustment); - arg0 = simplify_giv_expr (loop, tem, ext_val, benefit); - if (*ext_val) - { - if (!v->ext_dependent) - return arg0; - } - else - { - *ext_val = v->ext_dependent; - return arg0; - } - return 0; - } - - default: - do_default: - /* If it isn't an induction variable, and it is invariant, we - may be able to simplify things further by looking through - the bits we just moved outside the loop. */ - if (loop_invariant_p (loop, x) == 1) - { - struct movable *m; - struct loop_movables *movables = LOOP_MOVABLES (loop); - - for (m = movables->head; m; m = m->next) - if (rtx_equal_p (x, m->set_dest)) - { - /* Ok, we found a match. Substitute and simplify. */ - - /* If we match another movable, we must use that, as - this one is going away. */ - if (m->match) - return simplify_giv_expr (loop, m->match->set_dest, - ext_val, benefit); - - /* If consec is nonzero, this is a member of a group of - instructions that were moved together. We handle this - case only to the point of seeking to the last insn and - looking for a REG_EQUAL. Fail if we don't find one. */ - if (m->consec != 0) - { - int i = m->consec; - tem = m->insn; - do - { - tem = NEXT_INSN (tem); - } - while (--i > 0); - - tem = find_reg_note (tem, REG_EQUAL, NULL_RTX); - if (tem) - tem = XEXP (tem, 0); - } - else - { - tem = single_set (m->insn); - if (tem) - tem = SET_SRC (tem); - } - - if (tem) - { - /* What we are most interested in is pointer - arithmetic on invariants -- only take - patterns we may be able to do something with. */ - if (GET_CODE (tem) == PLUS - || GET_CODE (tem) == MULT - || GET_CODE (tem) == ASHIFT - || GET_CODE (tem) == CONST_INT - || GET_CODE (tem) == SYMBOL_REF) - { - tem = simplify_giv_expr (loop, tem, ext_val, - benefit); - if (tem) - return tem; - } - else if (GET_CODE (tem) == CONST - && GET_CODE (XEXP (tem, 0)) == PLUS - && GET_CODE (XEXP (XEXP (tem, 0), 0)) == SYMBOL_REF - && GET_CODE (XEXP (XEXP (tem, 0), 1)) == CONST_INT) - { - tem = simplify_giv_expr (loop, XEXP (tem, 0), - ext_val, benefit); - if (tem) - return tem; - } - } - break; - } - } - break; - } - - /* Fall through to general case. */ - default: - /* If invariant, return as USE (unless CONST_INT). - Otherwise, not giv. */ - if (GET_CODE (x) == USE) - x = XEXP (x, 0); - - if (loop_invariant_p (loop, x) == 1) - { - if (GET_CODE (x) == CONST_INT) - return x; - if (GET_CODE (x) == CONST - && GET_CODE (XEXP (x, 0)) == PLUS - && GET_CODE (XEXP (XEXP (x, 0), 0)) == SYMBOL_REF - && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT) - x = XEXP (x, 0); - return gen_rtx_USE (mode, x); - } - else - return 0; - } -} - -/* This routine folds invariants such that there is only ever one - CONST_INT in the summation. It is only used by simplify_giv_expr. */ - -static rtx -sge_plus_constant (rtx x, rtx c) -{ - if (GET_CODE (x) == CONST_INT) - return GEN_INT (INTVAL (x) + INTVAL (c)); - else if (GET_CODE (x) != PLUS) - return gen_rtx_PLUS (GET_MODE (x), x, c); - else if (GET_CODE (XEXP (x, 1)) == CONST_INT) - { - return gen_rtx_PLUS (GET_MODE (x), XEXP (x, 0), - GEN_INT (INTVAL (XEXP (x, 1)) + INTVAL (c))); - } - else if (GET_CODE (XEXP (x, 0)) == PLUS - || GET_CODE (XEXP (x, 1)) != PLUS) - { - return gen_rtx_PLUS (GET_MODE (x), - sge_plus_constant (XEXP (x, 0), c), XEXP (x, 1)); - } - else - { - return gen_rtx_PLUS (GET_MODE (x), - sge_plus_constant (XEXP (x, 1), c), XEXP (x, 0)); - } -} - -static rtx -sge_plus (enum machine_mode mode, rtx x, rtx y) -{ - while (GET_CODE (y) == PLUS) - { - rtx a = XEXP (y, 0); - if (GET_CODE (a) == CONST_INT) - x = sge_plus_constant (x, a); - else - x = gen_rtx_PLUS (mode, x, a); - y = XEXP (y, 1); - } - if (GET_CODE (y) == CONST_INT) - x = sge_plus_constant (x, y); - else - x = gen_rtx_PLUS (mode, x, y); - return x; -} - -/* Help detect a giv that is calculated by several consecutive insns; - for example, - giv = biv * M - giv = giv + A - The caller has already identified the first insn P as having a giv as dest; - we check that all other insns that set the same register follow - immediately after P, that they alter nothing else, - and that the result of the last is still a giv. - - The value is 0 if the reg set in P is not really a giv. - Otherwise, the value is the amount gained by eliminating - all the consecutive insns that compute the value. - - FIRST_BENEFIT is the amount gained by eliminating the first insn, P. - SRC_REG is the reg of the biv; DEST_REG is the reg of the giv. - - The coefficients of the ultimate giv value are stored in - *MULT_VAL and *ADD_VAL. */ - -static int -consec_sets_giv (const struct loop *loop, int first_benefit, rtx p, - rtx src_reg, rtx dest_reg, rtx *add_val, rtx *mult_val, - rtx *ext_val, rtx *last_consec_insn) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct loop_regs *regs = LOOP_REGS (loop); - int count; - enum rtx_code code; - int benefit; - rtx temp; - rtx set; - - /* Indicate that this is a giv so that we can update the value produced in - each insn of the multi-insn sequence. - - This induction structure will be used only by the call to - general_induction_var below, so we can allocate it on our stack. - If this is a giv, our caller will replace the induct var entry with - a new induction structure. */ - struct induction *v; - - if (REG_IV_TYPE (ivs, REGNO (dest_reg)) != UNKNOWN_INDUCT) - return 0; - - v = alloca (sizeof (struct induction)); - v->src_reg = src_reg; - v->mult_val = *mult_val; - v->add_val = *add_val; - v->benefit = first_benefit; - v->cant_derive = 0; - v->derive_adjustment = 0; - v->ext_dependent = NULL_RTX; - - REG_IV_TYPE (ivs, REGNO (dest_reg)) = GENERAL_INDUCT; - REG_IV_INFO (ivs, REGNO (dest_reg)) = v; - - count = regs->array[REGNO (dest_reg)].n_times_set - 1; - - while (count > 0) - { - p = NEXT_INSN (p); - code = GET_CODE (p); - - /* If libcall, skip to end of call sequence. */ - if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) - p = XEXP (temp, 0); - - if (code == INSN - && (set = single_set (p)) - && GET_CODE (SET_DEST (set)) == REG - && SET_DEST (set) == dest_reg - && (general_induction_var (loop, SET_SRC (set), &src_reg, - add_val, mult_val, ext_val, 0, - &benefit, VOIDmode) - /* Giv created by equivalent expression. */ - || ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX)) - && general_induction_var (loop, XEXP (temp, 0), &src_reg, - add_val, mult_val, ext_val, 0, - &benefit, VOIDmode))) - && src_reg == v->src_reg) - { - if (find_reg_note (p, REG_RETVAL, NULL_RTX)) - benefit += libcall_benefit (p); - - count--; - v->mult_val = *mult_val; - v->add_val = *add_val; - v->benefit += benefit; - } - else if (code != NOTE) - { - /* Allow insns that set something other than this giv to a - constant. Such insns are needed on machines which cannot - include long constants and should not disqualify a giv. */ - if (code == INSN - && (set = single_set (p)) - && SET_DEST (set) != dest_reg - && CONSTANT_P (SET_SRC (set))) - continue; - - REG_IV_TYPE (ivs, REGNO (dest_reg)) = UNKNOWN_INDUCT; - return 0; - } - } - - REG_IV_TYPE (ivs, REGNO (dest_reg)) = UNKNOWN_INDUCT; - *last_consec_insn = p; - return v->benefit; -} - -/* Return an rtx, if any, that expresses giv G2 as a function of the register - represented by G1. If no such expression can be found, or it is clear that - it cannot possibly be a valid address, 0 is returned. - - To perform the computation, we note that - G1 = x * v + a and - G2 = y * v + b - where `v' is the biv. - - So G2 = (y/b) * G1 + (b - a*y/x). - - Note that MULT = y/x. - - Update: A and B are now allowed to be additive expressions such that - B contains all variables in A. That is, computing B-A will not require - subtracting variables. */ - -static rtx -express_from_1 (rtx a, rtx b, rtx mult) -{ - /* If MULT is zero, then A*MULT is zero, and our expression is B. */ - - if (mult == const0_rtx) - return b; - - /* If MULT is not 1, we cannot handle A with non-constants, since we - would then be required to subtract multiples of the registers in A. - This is theoretically possible, and may even apply to some Fortran - constructs, but it is a lot of work and we do not attempt it here. */ - - if (mult != const1_rtx && GET_CODE (a) != CONST_INT) - return NULL_RTX; - - /* In general these structures are sorted top to bottom (down the PLUS - chain), but not left to right across the PLUS. If B is a higher - order giv than A, we can strip one level and recurse. If A is higher - order, we'll eventually bail out, but won't know that until the end. - If they are the same, we'll strip one level around this loop. */ - - while (GET_CODE (a) == PLUS && GET_CODE (b) == PLUS) - { - rtx ra, rb, oa, ob, tmp; - - ra = XEXP (a, 0), oa = XEXP (a, 1); - if (GET_CODE (ra) == PLUS) - tmp = ra, ra = oa, oa = tmp; - - rb = XEXP (b, 0), ob = XEXP (b, 1); - if (GET_CODE (rb) == PLUS) - tmp = rb, rb = ob, ob = tmp; - - if (rtx_equal_p (ra, rb)) - /* We matched: remove one reg completely. */ - a = oa, b = ob; - else if (GET_CODE (ob) != PLUS && rtx_equal_p (ra, ob)) - /* An alternate match. */ - a = oa, b = rb; - else if (GET_CODE (oa) != PLUS && rtx_equal_p (oa, rb)) - /* An alternate match. */ - a = ra, b = ob; - else - { - /* Indicates an extra register in B. Strip one level from B and - recurse, hoping B was the higher order expression. */ - ob = express_from_1 (a, ob, mult); - if (ob == NULL_RTX) - return NULL_RTX; - return gen_rtx_PLUS (GET_MODE (b), rb, ob); - } - } - - /* Here we are at the last level of A, go through the cases hoping to - get rid of everything but a constant. */ - - if (GET_CODE (a) == PLUS) - { - rtx ra, oa; - - ra = XEXP (a, 0), oa = XEXP (a, 1); - if (rtx_equal_p (oa, b)) - oa = ra; - else if (!rtx_equal_p (ra, b)) - return NULL_RTX; - - if (GET_CODE (oa) != CONST_INT) - return NULL_RTX; - - return GEN_INT (-INTVAL (oa) * INTVAL (mult)); - } - else if (GET_CODE (a) == CONST_INT) - { - return plus_constant (b, -INTVAL (a) * INTVAL (mult)); - } - else if (CONSTANT_P (a)) - { - enum machine_mode mode_a = GET_MODE (a); - enum machine_mode mode_b = GET_MODE (b); - enum machine_mode mode = mode_b == VOIDmode ? mode_a : mode_b; - return simplify_gen_binary (MINUS, mode, b, a); - } - else if (GET_CODE (b) == PLUS) - { - if (rtx_equal_p (a, XEXP (b, 0))) - return XEXP (b, 1); - else if (rtx_equal_p (a, XEXP (b, 1))) - return XEXP (b, 0); - else - return NULL_RTX; - } - else if (rtx_equal_p (a, b)) - return const0_rtx; - - return NULL_RTX; -} - -rtx -express_from (struct induction *g1, struct induction *g2) -{ - rtx mult, add; - - /* The value that G1 will be multiplied by must be a constant integer. Also, - the only chance we have of getting a valid address is if b*c/a (see above - for notation) is also an integer. */ - if (GET_CODE (g1->mult_val) == CONST_INT - && GET_CODE (g2->mult_val) == CONST_INT) - { - if (g1->mult_val == const0_rtx - || (g1->mult_val == constm1_rtx - && INTVAL (g2->mult_val) - == (HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT - 1)) - || INTVAL (g2->mult_val) % INTVAL (g1->mult_val) != 0) - return NULL_RTX; - mult = GEN_INT (INTVAL (g2->mult_val) / INTVAL (g1->mult_val)); - } - else if (rtx_equal_p (g1->mult_val, g2->mult_val)) - mult = const1_rtx; - else - { - /* ??? Find out if the one is a multiple of the other? */ - return NULL_RTX; - } - - add = express_from_1 (g1->add_val, g2->add_val, mult); - if (add == NULL_RTX) - { - /* Failed. If we've got a multiplication factor between G1 and G2, - scale G1's addend and try again. */ - if (INTVAL (mult) > 1) - { - rtx g1_add_val = g1->add_val; - if (GET_CODE (g1_add_val) == MULT - && GET_CODE (XEXP (g1_add_val, 1)) == CONST_INT) - { - HOST_WIDE_INT m; - m = INTVAL (mult) * INTVAL (XEXP (g1_add_val, 1)); - g1_add_val = gen_rtx_MULT (GET_MODE (g1_add_val), - XEXP (g1_add_val, 0), GEN_INT (m)); - } - else - { - g1_add_val = gen_rtx_MULT (GET_MODE (g1_add_val), g1_add_val, - mult); - } - - add = express_from_1 (g1_add_val, g2->add_val, const1_rtx); - } - } - if (add == NULL_RTX) - return NULL_RTX; - - /* Form simplified final result. */ - if (mult == const0_rtx) - return add; - else if (mult == const1_rtx) - mult = g1->dest_reg; - else - mult = gen_rtx_MULT (g2->mode, g1->dest_reg, mult); - - if (add == const0_rtx) - return mult; - else - { - if (GET_CODE (add) == PLUS - && CONSTANT_P (XEXP (add, 1))) - { - rtx tem = XEXP (add, 1); - mult = gen_rtx_PLUS (g2->mode, mult, XEXP (add, 0)); - add = tem; - } - - return gen_rtx_PLUS (g2->mode, mult, add); - } -} - -/* Return an rtx, if any, that expresses giv G2 as a function of the register - represented by G1. This indicates that G2 should be combined with G1 and - that G2 can use (either directly or via an address expression) a register - used to represent G1. */ - -static rtx -combine_givs_p (struct induction *g1, struct induction *g2) -{ - rtx comb, ret; - - /* With the introduction of ext dependent givs, we must care for modes. - G2 must not use a wider mode than G1. */ - if (GET_MODE_SIZE (g1->mode) < GET_MODE_SIZE (g2->mode)) - return NULL_RTX; - - ret = comb = express_from (g1, g2); - if (comb == NULL_RTX) - return NULL_RTX; - if (g1->mode != g2->mode) - ret = gen_lowpart (g2->mode, comb); - - /* If these givs are identical, they can be combined. We use the results - of express_from because the addends are not in a canonical form, so - rtx_equal_p is a weaker test. */ - /* But don't combine a DEST_REG giv with a DEST_ADDR giv; we want the - combination to be the other way round. */ - if (comb == g1->dest_reg - && (g1->giv_type == DEST_REG || g2->giv_type == DEST_ADDR)) - { - return ret; - } - - /* If G2 can be expressed as a function of G1 and that function is valid - as an address and no more expensive than using a register for G2, - the expression of G2 in terms of G1 can be used. */ - if (ret != NULL_RTX - && g2->giv_type == DEST_ADDR - && memory_address_p (GET_MODE (g2->mem), ret)) - return ret; - - return NULL_RTX; -} - -/* See if BL is monotonic and has a constant per-iteration increment. - Return the increment if so, otherwise return 0. */ - -static HOST_WIDE_INT -get_monotonic_increment (struct iv_class *bl) -{ - struct induction *v; - rtx incr; - - /* Get the total increment and check that it is constant. */ - incr = biv_total_increment (bl); - if (incr == 0 || GET_CODE (incr) != CONST_INT) - return 0; - - for (v = bl->biv; v != 0; v = v->next_iv) - { - if (GET_CODE (v->add_val) != CONST_INT) - return 0; - - if (INTVAL (v->add_val) < 0 && INTVAL (incr) >= 0) - return 0; - - if (INTVAL (v->add_val) > 0 && INTVAL (incr) <= 0) - return 0; - } - return INTVAL (incr); -} - - -/* Subroutine of biv_fits_mode_p. Return true if biv BL, when biased by - BIAS, will never exceed the unsigned range of MODE. LOOP is the loop - to which the biv belongs and INCR is its per-iteration increment. */ - -static bool -biased_biv_fits_mode_p (const struct loop *loop, struct iv_class *bl, - HOST_WIDE_INT incr, enum machine_mode mode, - unsigned HOST_WIDE_INT bias) -{ - unsigned HOST_WIDE_INT initial, maximum, span, delta; - - /* We need to be able to manipulate MODE-size constants. */ - if (HOST_BITS_PER_WIDE_INT < GET_MODE_BITSIZE (mode)) - return false; - - /* The number of loop iterations must be constant. */ - if (LOOP_INFO (loop)->n_iterations == 0) - return false; - - /* So must the biv's initial value. */ - if (bl->initial_value == 0 || GET_CODE (bl->initial_value) != CONST_INT) - return false; - - initial = bias + INTVAL (bl->initial_value); - maximum = GET_MODE_MASK (mode); - - /* Make sure that the initial value is within range. */ - if (initial > maximum) - return false; - - /* Set up DELTA and SPAN such that the number of iterations * DELTA - (calculated to arbitrary precision) must be <= SPAN. */ - if (incr < 0) - { - delta = -incr; - span = initial; - } - else - { - delta = incr; - /* Handle the special case in which MAXIMUM is the largest - unsigned HOST_WIDE_INT and INITIAL is 0. */ - if (maximum + 1 == initial) - span = LOOP_INFO (loop)->n_iterations * delta; - else - span = maximum + 1 - initial; - } - return (span / LOOP_INFO (loop)->n_iterations >= delta); -} - - -/* Return true if biv BL will never exceed the bounds of MODE. LOOP is - the loop to which BL belongs and INCR is its per-iteration increment. - UNSIGNEDP is true if the biv should be treated as unsigned. */ - -static bool -biv_fits_mode_p (const struct loop *loop, struct iv_class *bl, - HOST_WIDE_INT incr, enum machine_mode mode, bool unsignedp) -{ - struct loop_info *loop_info; - unsigned HOST_WIDE_INT bias; - - /* A biv's value will always be limited to its natural mode. - Larger modes will observe the same wrap-around. */ - if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (bl->biv->src_reg))) - mode = GET_MODE (bl->biv->src_reg); - - loop_info = LOOP_INFO (loop); - - bias = (unsignedp ? 0 : (GET_MODE_MASK (mode) >> 1) + 1); - if (biased_biv_fits_mode_p (loop, bl, incr, mode, bias)) - return true; - - if (mode == GET_MODE (bl->biv->src_reg) - && bl->biv->src_reg == loop_info->iteration_var - && loop_info->comparison_value - && loop_invariant_p (loop, loop_info->comparison_value)) - { - /* If the increment is +1, and the exit test is a <, the BIV - cannot overflow. (For <=, we have the problematic case that - the comparison value might be the maximum value of the range.) */ - if (incr == 1) - { - if (loop_info->comparison_code == LT) - return true; - if (loop_info->comparison_code == LTU && unsignedp) - return true; - } - - /* Likewise for increment -1 and exit test >. */ - if (incr == -1) - { - if (loop_info->comparison_code == GT) - return true; - if (loop_info->comparison_code == GTU && unsignedp) - return true; - } - } - return false; -} - - -/* Given that X is an extension or truncation of BL, return true - if it is unaffected by overflow. LOOP is the loop to which - BL belongs and INCR is its per-iteration increment. */ - -static bool -extension_within_bounds_p (const struct loop *loop, struct iv_class *bl, - HOST_WIDE_INT incr, rtx x) -{ - enum machine_mode mode; - bool signedp, unsignedp; - - switch (GET_CODE (x)) - { - case SIGN_EXTEND: - case ZERO_EXTEND: - mode = GET_MODE (XEXP (x, 0)); - signedp = (GET_CODE (x) == SIGN_EXTEND); - unsignedp = (GET_CODE (x) == ZERO_EXTEND); - break; - - case TRUNCATE: - /* We don't know whether this value is being used as signed - or unsigned, so check the conditions for both. */ - mode = GET_MODE (x); - signedp = unsignedp = true; - break; - - default: - abort (); - } - - return ((!signedp || biv_fits_mode_p (loop, bl, incr, mode, false)) - && (!unsignedp || biv_fits_mode_p (loop, bl, incr, mode, true))); -} - - -/* Check each extension dependent giv in this class to see if its - root biv is safe from wrapping in the interior mode, which would - make the giv illegal. */ - -static void -check_ext_dependent_givs (const struct loop *loop, struct iv_class *bl) -{ - struct induction *v; - HOST_WIDE_INT incr; - - incr = get_monotonic_increment (bl); - - /* Invalidate givs that fail the tests. */ - for (v = bl->giv; v; v = v->next_iv) - if (v->ext_dependent) - { - if (incr != 0 - && extension_within_bounds_p (loop, bl, incr, v->ext_dependent)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Verified ext dependent giv at %d of reg %d\n", - INSN_UID (v->insn), bl->regno); - } - else - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Failed ext dependent giv at %d\n", - INSN_UID (v->insn)); - - v->ignore = 1; - bl->all_reduced = 0; - } - } -} - -/* Generate a version of VALUE in a mode appropriate for initializing V. */ - -rtx -extend_value_for_giv (struct induction *v, rtx value) -{ - rtx ext_dep = v->ext_dependent; - - if (! ext_dep) - return value; - - /* Recall that check_ext_dependent_givs verified that the known bounds - of a biv did not overflow or wrap with respect to the extension for - the giv. Therefore, constants need no additional adjustment. */ - if (CONSTANT_P (value) && GET_MODE (value) == VOIDmode) - return value; - - /* Otherwise, we must adjust the value to compensate for the - differing modes of the biv and the giv. */ - return gen_rtx_fmt_e (GET_CODE (ext_dep), GET_MODE (ext_dep), value); -} - -struct combine_givs_stats -{ - int giv_number; - int total_benefit; -}; - -static int -cmp_combine_givs_stats (const void *xp, const void *yp) -{ - const struct combine_givs_stats * const x = - (const struct combine_givs_stats *) xp; - const struct combine_givs_stats * const y = - (const struct combine_givs_stats *) yp; - int d; - d = y->total_benefit - x->total_benefit; - /* Stabilize the sort. */ - if (!d) - d = x->giv_number - y->giv_number; - return d; -} - -/* Check all pairs of givs for iv_class BL and see if any can be combined with - any other. If so, point SAME to the giv combined with and set NEW_REG to - be an expression (in terms of the other giv's DEST_REG) equivalent to the - giv. Also, update BENEFIT and related fields for cost/benefit analysis. */ - -static void -combine_givs (struct loop_regs *regs, struct iv_class *bl) -{ - /* Additional benefit to add for being combined multiple times. */ - const int extra_benefit = 3; - - struct induction *g1, *g2, **giv_array; - int i, j, k, giv_count; - struct combine_givs_stats *stats; - rtx *can_combine; - - /* Count givs, because bl->giv_count is incorrect here. */ - giv_count = 0; - for (g1 = bl->giv; g1; g1 = g1->next_iv) - if (!g1->ignore) - giv_count++; - - giv_array = alloca (giv_count * sizeof (struct induction *)); - i = 0; - for (g1 = bl->giv; g1; g1 = g1->next_iv) - if (!g1->ignore) - giv_array[i++] = g1; - - stats = xcalloc (giv_count, sizeof (*stats)); - can_combine = xcalloc (giv_count, giv_count * sizeof (rtx)); - - for (i = 0; i < giv_count; i++) - { - int this_benefit; - rtx single_use; - - g1 = giv_array[i]; - stats[i].giv_number = i; - - /* If a DEST_REG GIV is used only once, do not allow it to combine - with anything, for in doing so we will gain nothing that cannot - be had by simply letting the GIV with which we would have combined - to be reduced on its own. The losage shows up in particular with - DEST_ADDR targets on hosts with reg+reg addressing, though it can - be seen elsewhere as well. */ - if (g1->giv_type == DEST_REG - && (single_use = regs->array[REGNO (g1->dest_reg)].single_usage) - && single_use != const0_rtx) - continue; - - this_benefit = g1->benefit; - /* Add an additional weight for zero addends. */ - if (g1->no_const_addval) - this_benefit += 1; - - for (j = 0; j < giv_count; j++) - { - rtx this_combine; - - g2 = giv_array[j]; - if (g1 != g2 - && (this_combine = combine_givs_p (g1, g2)) != NULL_RTX) - { - can_combine[i * giv_count + j] = this_combine; - this_benefit += g2->benefit + extra_benefit; - } - } - stats[i].total_benefit = this_benefit; - } - - /* Iterate, combining until we can't. */ -restart: - qsort (stats, giv_count, sizeof (*stats), cmp_combine_givs_stats); - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "Sorted combine statistics:\n"); - for (k = 0; k < giv_count; k++) - { - g1 = giv_array[stats[k].giv_number]; - if (!g1->combined_with && !g1->same) - fprintf (loop_dump_stream, " {%d, %d}", - INSN_UID (giv_array[stats[k].giv_number]->insn), - stats[k].total_benefit); - } - putc ('\n', loop_dump_stream); - } - - for (k = 0; k < giv_count; k++) - { - int g1_add_benefit = 0; - - i = stats[k].giv_number; - g1 = giv_array[i]; - - /* If it has already been combined, skip. */ - if (g1->combined_with || g1->same) - continue; - - for (j = 0; j < giv_count; j++) - { - g2 = giv_array[j]; - if (g1 != g2 && can_combine[i * giv_count + j] - /* If it has already been combined, skip. */ - && ! g2->same && ! g2->combined_with) - { - int l; - - g2->new_reg = can_combine[i * giv_count + j]; - g2->same = g1; - /* For destination, we now may replace by mem expression instead - of register. This changes the costs considerably, so add the - compensation. */ - if (g2->giv_type == DEST_ADDR) - g2->benefit = (g2->benefit + reg_address_cost - - address_cost (g2->new_reg, - GET_MODE (g2->mem))); - g1->combined_with++; - g1->lifetime += g2->lifetime; - - g1_add_benefit += g2->benefit; - - /* ??? The new final_[bg]iv_value code does a much better job - of finding replaceable giv's, and hence this code may no - longer be necessary. */ - if (! g2->replaceable && REG_USERVAR_P (g2->dest_reg)) - g1_add_benefit -= copy_cost; - - /* To help optimize the next set of combinations, remove - this giv from the benefits of other potential mates. */ - for (l = 0; l < giv_count; ++l) - { - int m = stats[l].giv_number; - if (can_combine[m * giv_count + j]) - stats[l].total_benefit -= g2->benefit + extra_benefit; - } - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "giv at %d combined with giv at %d; new benefit %d + %d, lifetime %d\n", - INSN_UID (g2->insn), INSN_UID (g1->insn), - g1->benefit, g1_add_benefit, g1->lifetime); - } - } - - /* To help optimize the next set of combinations, remove - this giv from the benefits of other potential mates. */ - if (g1->combined_with) - { - for (j = 0; j < giv_count; ++j) - { - int m = stats[j].giv_number; - if (can_combine[m * giv_count + i]) - stats[j].total_benefit -= g1->benefit + extra_benefit; - } - - g1->benefit += g1_add_benefit; - - /* We've finished with this giv, and everything it touched. - Restart the combination so that proper weights for the - rest of the givs are properly taken into account. */ - /* ??? Ideally we would compact the arrays at this point, so - as to not cover old ground. But sanely compacting - can_combine is tricky. */ - goto restart; - } - } - - /* Clean up. */ - free (stats); - free (can_combine); -} - -/* Generate sequence for REG = B * M + A. B is the initial value of - the basic induction variable, M a multiplicative constant, A an - additive constant and REG the destination register. */ - -static rtx -gen_add_mult (rtx b, rtx m, rtx a, rtx reg) -{ - rtx seq; - rtx result; - - start_sequence (); - /* Use unsigned arithmetic. */ - result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 1); - if (reg != result) - emit_move_insn (reg, result); - seq = get_insns (); - end_sequence (); - - return seq; -} - - -/* Update registers created in insn sequence SEQ. */ - -static void -loop_regs_update (const struct loop *loop ATTRIBUTE_UNUSED, rtx seq) -{ - rtx insn; - - /* Update register info for alias analysis. */ - - insn = seq; - while (insn != NULL_RTX) - { - rtx set = single_set (insn); - - if (set && GET_CODE (SET_DEST (set)) == REG) - record_base_value (REGNO (SET_DEST (set)), SET_SRC (set), 0); - - insn = NEXT_INSN (insn); - } -} - - -/* EMIT code before BEFORE_BB/BEFORE_INSN to set REG = B * M + A. B - is the initial value of the basic induction variable, M a - multiplicative constant, A an additive constant and REG the - destination register. */ - -void -loop_iv_add_mult_emit_before (const struct loop *loop, rtx b, rtx m, rtx a, - rtx reg, basic_block before_bb, rtx before_insn) -{ - rtx seq; - - if (! before_insn) - { - loop_iv_add_mult_hoist (loop, b, m, a, reg); - return; - } - - /* Use copy_rtx to prevent unexpected sharing of these rtx. */ - seq = gen_add_mult (copy_rtx (b), copy_rtx (m), copy_rtx (a), reg); - - /* Increase the lifetime of any invariants moved further in code. */ - update_reg_last_use (a, before_insn); - update_reg_last_use (b, before_insn); - update_reg_last_use (m, before_insn); - - /* It is possible that the expansion created lots of new registers. - Iterate over the sequence we just created and record them all. We - must do this before inserting the sequence. */ - loop_regs_update (loop, seq); - - loop_insn_emit_before (loop, before_bb, before_insn, seq); -} - - -/* Emit insns in loop pre-header to set REG = B * M + A. B is the - initial value of the basic induction variable, M a multiplicative - constant, A an additive constant and REG the destination - register. */ - -void -loop_iv_add_mult_sink (const struct loop *loop, rtx b, rtx m, rtx a, rtx reg) -{ - rtx seq; - - /* Use copy_rtx to prevent unexpected sharing of these rtx. */ - seq = gen_add_mult (copy_rtx (b), copy_rtx (m), copy_rtx (a), reg); - - /* Increase the lifetime of any invariants moved further in code. - ???? Is this really necessary? */ - update_reg_last_use (a, loop->sink); - update_reg_last_use (b, loop->sink); - update_reg_last_use (m, loop->sink); - - /* It is possible that the expansion created lots of new registers. - Iterate over the sequence we just created and record them all. We - must do this before inserting the sequence. */ - loop_regs_update (loop, seq); - - loop_insn_sink (loop, seq); -} - - -/* Emit insns after loop to set REG = B * M + A. B is the initial - value of the basic induction variable, M a multiplicative constant, - A an additive constant and REG the destination register. */ - -void -loop_iv_add_mult_hoist (const struct loop *loop, rtx b, rtx m, rtx a, rtx reg) -{ - rtx seq; - - /* Use copy_rtx to prevent unexpected sharing of these rtx. */ - seq = gen_add_mult (copy_rtx (b), copy_rtx (m), copy_rtx (a), reg); - - /* It is possible that the expansion created lots of new registers. - Iterate over the sequence we just created and record them all. We - must do this before inserting the sequence. */ - loop_regs_update (loop, seq); - - loop_insn_hoist (loop, seq); -} - - - -/* Similar to gen_add_mult, but compute cost rather than generating - sequence. */ - -static int -iv_add_mult_cost (rtx b, rtx m, rtx a, rtx reg) -{ - int cost = 0; - rtx last, result; - - start_sequence (); - result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 1); - if (reg != result) - emit_move_insn (reg, result); - last = get_last_insn (); - while (last) - { - rtx t = single_set (last); - if (t) - cost += rtx_cost (SET_SRC (t), SET); - last = PREV_INSN (last); - } - end_sequence (); - return cost; -} - -/* Test whether A * B can be computed without - an actual multiply insn. Value is 1 if so. - - ??? This function stinks because it generates a ton of wasted RTL - ??? and as a result fragments GC memory to no end. There are other - ??? places in the compiler which are invoked a lot and do the same - ??? thing, generate wasted RTL just to see if something is possible. */ - -static int -product_cheap_p (rtx a, rtx b) -{ - rtx tmp; - int win, n_insns; - - /* If only one is constant, make it B. */ - if (GET_CODE (a) == CONST_INT) - tmp = a, a = b, b = tmp; - - /* If first constant, both constant, so don't need multiply. */ - if (GET_CODE (a) == CONST_INT) - return 1; - - /* If second not constant, neither is constant, so would need multiply. */ - if (GET_CODE (b) != CONST_INT) - return 0; - - /* One operand is constant, so might not need multiply insn. Generate the - code for the multiply and see if a call or multiply, or long sequence - of insns is generated. */ - - start_sequence (); - expand_mult (GET_MODE (a), a, b, NULL_RTX, 1); - tmp = get_insns (); - end_sequence (); - - win = 1; - if (INSN_P (tmp)) - { - n_insns = 0; - while (tmp != NULL_RTX) - { - rtx next = NEXT_INSN (tmp); - - if (++n_insns > 3 - || GET_CODE (tmp) != INSN - || (GET_CODE (PATTERN (tmp)) == SET - && GET_CODE (SET_SRC (PATTERN (tmp))) == MULT) - || (GET_CODE (PATTERN (tmp)) == PARALLEL - && GET_CODE (XVECEXP (PATTERN (tmp), 0, 0)) == SET - && GET_CODE (SET_SRC (XVECEXP (PATTERN (tmp), 0, 0))) == MULT)) - { - win = 0; - break; - } - - tmp = next; - } - } - else if (GET_CODE (tmp) == SET - && GET_CODE (SET_SRC (tmp)) == MULT) - win = 0; - else if (GET_CODE (tmp) == PARALLEL - && GET_CODE (XVECEXP (tmp, 0, 0)) == SET - && GET_CODE (SET_SRC (XVECEXP (tmp, 0, 0))) == MULT) - win = 0; - - return win; -} - -/* Check to see if loop can be terminated by a "decrement and branch until - zero" instruction. If so, add a REG_NONNEG note to the branch insn if so. - Also try reversing an increment loop to a decrement loop - to see if the optimization can be performed. - Value is nonzero if optimization was performed. */ - -/* This is useful even if the architecture doesn't have such an insn, - because it might change a loops which increments from 0 to n to a loop - which decrements from n to 0. A loop that decrements to zero is usually - faster than one that increments from zero. */ - -/* ??? This could be rewritten to use some of the loop unrolling procedures, - such as approx_final_value, biv_total_increment, loop_iterations, and - final_[bg]iv_value. */ - -static int -check_dbra_loop (struct loop *loop, int insn_count) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_regs *regs = LOOP_REGS (loop); - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - rtx reg; - enum machine_mode mode; - rtx jump_label; - rtx final_value; - rtx start_value; - rtx new_add_val; - rtx comparison; - rtx before_comparison; - rtx p; - rtx jump; - rtx first_compare; - int compare_and_branch; - rtx loop_start = loop->start; - rtx loop_end = loop->end; - - /* If last insn is a conditional branch, and the insn before tests a - register value, try to optimize it. Otherwise, we can't do anything. */ - - jump = PREV_INSN (loop_end); - comparison = get_condition_for_loop (loop, jump); - if (comparison == 0) - return 0; - if (!onlyjump_p (jump)) - return 0; - - /* Try to compute whether the compare/branch at the loop end is one or - two instructions. */ - get_condition (jump, &first_compare, false); - if (first_compare == jump) - compare_and_branch = 1; - else if (first_compare == prev_nonnote_insn (jump)) - compare_and_branch = 2; - else - return 0; - - { - /* If more than one condition is present to control the loop, then - do not proceed, as this function does not know how to rewrite - loop tests with more than one condition. - - Look backwards from the first insn in the last comparison - sequence and see if we've got another comparison sequence. */ - - rtx jump1; - if ((jump1 = prev_nonnote_insn (first_compare)) != loop->cont) - if (GET_CODE (jump1) == JUMP_INSN) - return 0; - } - - /* Check all of the bivs to see if the compare uses one of them. - Skip biv's set more than once because we can't guarantee that - it will be zero on the last iteration. Also skip if the biv is - used between its update and the test insn. */ - - for (bl = ivs->list; bl; bl = bl->next) - { - if (bl->biv_count == 1 - && ! bl->biv->maybe_multiple - && bl->biv->dest_reg == XEXP (comparison, 0) - && ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn, - first_compare)) - break; - } - - /* Try swapping the comparison to identify a suitable biv. */ - if (!bl) - for (bl = ivs->list; bl; bl = bl->next) - if (bl->biv_count == 1 - && ! bl->biv->maybe_multiple - && bl->biv->dest_reg == XEXP (comparison, 1) - && ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn, - first_compare)) - { - comparison = gen_rtx_fmt_ee (swap_condition (GET_CODE (comparison)), - VOIDmode, - XEXP (comparison, 1), - XEXP (comparison, 0)); - break; - } - - if (! bl) - return 0; - - /* Look for the case where the basic induction variable is always - nonnegative, and equals zero on the last iteration. - In this case, add a reg_note REG_NONNEG, which allows the - m68k DBRA instruction to be used. */ - - if (((GET_CODE (comparison) == GT && XEXP (comparison, 1) == constm1_rtx) - || (GET_CODE (comparison) == NE && XEXP (comparison, 1) == const0_rtx)) - && GET_CODE (bl->biv->add_val) == CONST_INT - && INTVAL (bl->biv->add_val) < 0) - { - /* Initial value must be greater than 0, - init_val % -dec_value == 0 to ensure that it equals zero on - the last iteration */ - - if (GET_CODE (bl->initial_value) == CONST_INT - && INTVAL (bl->initial_value) > 0 - && (INTVAL (bl->initial_value) - % (-INTVAL (bl->biv->add_val))) == 0) - { - /* Register always nonnegative, add REG_NOTE to branch. */ - if (! find_reg_note (jump, REG_NONNEG, NULL_RTX)) - REG_NOTES (jump) - = gen_rtx_EXPR_LIST (REG_NONNEG, bl->biv->dest_reg, - REG_NOTES (jump)); - bl->nonneg = 1; - - return 1; - } - - /* If the decrement is 1 and the value was tested as >= 0 before - the loop, then we can safely optimize. */ - for (p = loop_start; p; p = PREV_INSN (p)) - { - if (GET_CODE (p) == CODE_LABEL) - break; - if (GET_CODE (p) != JUMP_INSN) - continue; - - before_comparison = get_condition_for_loop (loop, p); - if (before_comparison - && XEXP (before_comparison, 0) == bl->biv->dest_reg - && (GET_CODE (before_comparison) == LT - || GET_CODE (before_comparison) == LTU) - && XEXP (before_comparison, 1) == const0_rtx - && ! reg_set_between_p (bl->biv->dest_reg, p, loop_start) - && INTVAL (bl->biv->add_val) == -1) - { - if (! find_reg_note (jump, REG_NONNEG, NULL_RTX)) - REG_NOTES (jump) - = gen_rtx_EXPR_LIST (REG_NONNEG, bl->biv->dest_reg, - REG_NOTES (jump)); - bl->nonneg = 1; - - return 1; - } - } - } - else if (GET_CODE (bl->biv->add_val) == CONST_INT - && INTVAL (bl->biv->add_val) > 0) - { - /* Try to change inc to dec, so can apply above optimization. */ - /* Can do this if: - all registers modified are induction variables or invariant, - all memory references have non-overlapping addresses - (obviously true if only one write) - allow 2 insns for the compare/jump at the end of the loop. */ - /* Also, we must avoid any instructions which use both the reversed - biv and another biv. Such instructions will fail if the loop is - reversed. We meet this condition by requiring that either - no_use_except_counting is true, or else that there is only - one biv. */ - int num_nonfixed_reads = 0; - /* 1 if the iteration var is used only to count iterations. */ - int no_use_except_counting = 0; - /* 1 if the loop has no memory store, or it has a single memory store - which is reversible. */ - int reversible_mem_store = 1; - - if (bl->giv_count == 0 - && !loop->exit_count - && !loop_info->has_multiple_exit_targets) - { - rtx bivreg = regno_reg_rtx[bl->regno]; - struct iv_class *blt; - - /* If there are no givs for this biv, and the only exit is the - fall through at the end of the loop, then - see if perhaps there are no uses except to count. */ - no_use_except_counting = 1; - for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) - if (INSN_P (p)) - { - rtx set = single_set (p); - - if (set && GET_CODE (SET_DEST (set)) == REG - && REGNO (SET_DEST (set)) == bl->regno) - /* An insn that sets the biv is okay. */ - ; - else if (!reg_mentioned_p (bivreg, PATTERN (p))) - /* An insn that doesn't mention the biv is okay. */ - ; - else if (p == prev_nonnote_insn (prev_nonnote_insn (loop_end)) - || p == prev_nonnote_insn (loop_end)) - { - /* If either of these insns uses the biv and sets a pseudo - that has more than one usage, then the biv has uses - other than counting since it's used to derive a value - that is used more than one time. */ - note_stores (PATTERN (p), note_set_pseudo_multiple_uses, - regs); - if (regs->multiple_uses) - { - no_use_except_counting = 0; - break; - } - } - else - { - no_use_except_counting = 0; - break; - } - } - - /* A biv has uses besides counting if it is used to set - another biv. */ - for (blt = ivs->list; blt; blt = blt->next) - if (blt->init_set - && reg_mentioned_p (bivreg, SET_SRC (blt->init_set))) - { - no_use_except_counting = 0; - break; - } - } - - if (no_use_except_counting) - /* No need to worry about MEMs. */ - ; - else if (loop_info->num_mem_sets <= 1) - { - for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) - if (INSN_P (p)) - num_nonfixed_reads += count_nonfixed_reads (loop, PATTERN (p)); - - /* If the loop has a single store, and the destination address is - invariant, then we can't reverse the loop, because this address - might then have the wrong value at loop exit. - This would work if the source was invariant also, however, in that - case, the insn should have been moved out of the loop. */ - - if (loop_info->num_mem_sets == 1) - { - struct induction *v; - - /* If we could prove that each of the memory locations - written to was different, then we could reverse the - store -- but we don't presently have any way of - knowing that. */ - reversible_mem_store = 0; - - /* If the store depends on a register that is set after the - store, it depends on the initial value, and is thus not - reversible. */ - for (v = bl->giv; reversible_mem_store && v; v = v->next_iv) - { - if (v->giv_type == DEST_REG - && reg_mentioned_p (v->dest_reg, - PATTERN (loop_info->first_loop_store_insn)) - && loop_insn_first_p (loop_info->first_loop_store_insn, - v->insn)) - reversible_mem_store = 0; - } - } - } - else - return 0; - - /* This code only acts for innermost loops. Also it simplifies - the memory address check by only reversing loops with - zero or one memory access. - Two memory accesses could involve parts of the same array, - and that can't be reversed. - If the biv is used only for counting, than we don't need to worry - about all these things. */ - - if ((num_nonfixed_reads <= 1 - && ! loop_info->has_nonconst_call - && ! loop_info->has_prefetch - && ! loop_info->has_volatile - && reversible_mem_store - && (bl->giv_count + bl->biv_count + loop_info->num_mem_sets - + num_unmoved_movables (loop) + compare_and_branch == insn_count) - && (bl == ivs->list && bl->next == 0)) - || (no_use_except_counting && ! loop_info->has_prefetch)) - { - rtx tem; - - /* Loop can be reversed. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, "Can reverse loop\n"); - - /* Now check other conditions: - - The increment must be a constant, as must the initial value, - and the comparison code must be LT. - - This test can probably be improved since +/- 1 in the constant - can be obtained by changing LT to LE and vice versa; this is - confusing. */ - - if (comparison - /* for constants, LE gets turned into LT */ - && (GET_CODE (comparison) == LT - || (GET_CODE (comparison) == LE - && no_use_except_counting) - || GET_CODE (comparison) == LTU)) - { - HOST_WIDE_INT add_val, add_adjust, comparison_val = 0; - rtx initial_value, comparison_value; - int nonneg = 0; - enum rtx_code cmp_code; - int comparison_const_width; - unsigned HOST_WIDE_INT comparison_sign_mask; - bool keep_first_compare; - - add_val = INTVAL (bl->biv->add_val); - comparison_value = XEXP (comparison, 1); - if (GET_MODE (comparison_value) == VOIDmode) - comparison_const_width - = GET_MODE_BITSIZE (GET_MODE (XEXP (comparison, 0))); - else - comparison_const_width - = GET_MODE_BITSIZE (GET_MODE (comparison_value)); - if (comparison_const_width > HOST_BITS_PER_WIDE_INT) - comparison_const_width = HOST_BITS_PER_WIDE_INT; - comparison_sign_mask - = (unsigned HOST_WIDE_INT) 1 << (comparison_const_width - 1); - - /* If the comparison value is not a loop invariant, then we - can not reverse this loop. - - ??? If the insns which initialize the comparison value as - a whole compute an invariant result, then we could move - them out of the loop and proceed with loop reversal. */ - if (! loop_invariant_p (loop, comparison_value)) - return 0; - - if (GET_CODE (comparison_value) == CONST_INT) - comparison_val = INTVAL (comparison_value); - initial_value = bl->initial_value; - - /* Normalize the initial value if it is an integer and - has no other use except as a counter. This will allow - a few more loops to be reversed. */ - if (no_use_except_counting - && GET_CODE (comparison_value) == CONST_INT - && GET_CODE (initial_value) == CONST_INT) - { - comparison_val = comparison_val - INTVAL (bl->initial_value); - /* The code below requires comparison_val to be a multiple - of add_val in order to do the loop reversal, so - round up comparison_val to a multiple of add_val. - Since comparison_value is constant, we know that the - current comparison code is LT. */ - comparison_val = comparison_val + add_val - 1; - comparison_val - -= (unsigned HOST_WIDE_INT) comparison_val % add_val; - /* We postpone overflow checks for COMPARISON_VAL here; - even if there is an overflow, we might still be able to - reverse the loop, if converting the loop exit test to - NE is possible. */ - initial_value = const0_rtx; - } - - /* First check if we can do a vanilla loop reversal. */ - if (initial_value == const0_rtx - && GET_CODE (comparison_value) == CONST_INT - /* Now do postponed overflow checks on COMPARISON_VAL. */ - && ! (((comparison_val - add_val) ^ INTVAL (comparison_value)) - & comparison_sign_mask)) - { - /* Register will always be nonnegative, with value - 0 on last iteration */ - add_adjust = add_val; - nonneg = 1; - cmp_code = GE; - } - else - return 0; - - if (GET_CODE (comparison) == LE) - add_adjust -= add_val; - - /* If the initial value is not zero, or if the comparison - value is not an exact multiple of the increment, then we - can not reverse this loop. */ - if (initial_value == const0_rtx - && GET_CODE (comparison_value) == CONST_INT) - { - if (((unsigned HOST_WIDE_INT) comparison_val % add_val) != 0) - return 0; - } - else - { - if (! no_use_except_counting || add_val != 1) - return 0; - } - - final_value = comparison_value; - - /* Reset these in case we normalized the initial value - and comparison value above. */ - if (GET_CODE (comparison_value) == CONST_INT - && GET_CODE (initial_value) == CONST_INT) - { - comparison_value = GEN_INT (comparison_val); - final_value - = GEN_INT (comparison_val + INTVAL (bl->initial_value)); - } - bl->initial_value = initial_value; - - /* Save some info needed to produce the new insns. */ - reg = bl->biv->dest_reg; - mode = GET_MODE (reg); - jump_label = condjump_label (PREV_INSN (loop_end)); - new_add_val = GEN_INT (-INTVAL (bl->biv->add_val)); - - /* Set start_value; if this is not a CONST_INT, we need - to generate a SUB. - Initialize biv to start_value before loop start. - The old initializing insn will be deleted as a - dead store by flow.c. */ - if (initial_value == const0_rtx - && GET_CODE (comparison_value) == CONST_INT) - { - start_value - = gen_int_mode (comparison_val - add_adjust, mode); - loop_insn_hoist (loop, gen_move_insn (reg, start_value)); - } - else if (GET_CODE (initial_value) == CONST_INT) - { - rtx offset = GEN_INT (-INTVAL (initial_value) - add_adjust); - rtx add_insn = gen_add3_insn (reg, comparison_value, offset); - - if (add_insn == 0) - return 0; - - start_value - = gen_rtx_PLUS (mode, comparison_value, offset); - loop_insn_hoist (loop, add_insn); - if (GET_CODE (comparison) == LE) - final_value = gen_rtx_PLUS (mode, comparison_value, - GEN_INT (add_val)); - } - else if (! add_adjust) - { - rtx sub_insn = gen_sub3_insn (reg, comparison_value, - initial_value); - - if (sub_insn == 0) - return 0; - start_value - = gen_rtx_MINUS (mode, comparison_value, initial_value); - loop_insn_hoist (loop, sub_insn); - } - else - /* We could handle the other cases too, but it'll be - better to have a testcase first. */ - return 0; - - /* We may not have a single insn which can increment a reg, so - create a sequence to hold all the insns from expand_inc. */ - start_sequence (); - expand_inc (reg, new_add_val); - tem = get_insns (); - end_sequence (); - - p = loop_insn_emit_before (loop, 0, bl->biv->insn, tem); - delete_insn (bl->biv->insn); - - /* Update biv info to reflect its new status. */ - bl->biv->insn = p; - bl->initial_value = start_value; - bl->biv->add_val = new_add_val; - - /* Update loop info. */ - loop_info->initial_value = reg; - loop_info->initial_equiv_value = reg; - loop_info->final_value = const0_rtx; - loop_info->final_equiv_value = const0_rtx; - loop_info->comparison_value = const0_rtx; - loop_info->comparison_code = cmp_code; - loop_info->increment = new_add_val; - - /* Inc LABEL_NUSES so that delete_insn will - not delete the label. */ - LABEL_NUSES (XEXP (jump_label, 0))++; - - /* If we have a separate comparison insn that does more - than just set cc0, the result of the comparison might - be used outside the loop. */ - keep_first_compare = (compare_and_branch == 2 -#ifdef HAVE_CC0 - && sets_cc0_p (first_compare) <= 0 -#endif - ); - - /* Emit an insn after the end of the loop to set the biv's - proper exit value if it is used anywhere outside the loop. */ - if (keep_first_compare - || (REGNO_LAST_UID (bl->regno) != INSN_UID (first_compare)) - || ! bl->init_insn - || REGNO_FIRST_UID (bl->regno) != INSN_UID (bl->init_insn)) - loop_insn_sink (loop, gen_load_of_final_value (reg, final_value)); - - if (keep_first_compare) - loop_insn_sink (loop, PATTERN (first_compare)); - - /* Delete compare/branch at end of loop. */ - delete_related_insns (PREV_INSN (loop_end)); - if (compare_and_branch == 2) - delete_related_insns (first_compare); - - /* Add new compare/branch insn at end of loop. */ - start_sequence (); - emit_cmp_and_jump_insns (reg, const0_rtx, cmp_code, NULL_RTX, - mode, 0, - XEXP (jump_label, 0)); - tem = get_insns (); - end_sequence (); - emit_jump_insn_before (tem, loop_end); - - for (tem = PREV_INSN (loop_end); - tem && GET_CODE (tem) != JUMP_INSN; - tem = PREV_INSN (tem)) - ; - - if (tem) - JUMP_LABEL (tem) = XEXP (jump_label, 0); - - if (nonneg) - { - if (tem) - { - /* Increment of LABEL_NUSES done above. */ - /* Register is now always nonnegative, - so add REG_NONNEG note to the branch. */ - REG_NOTES (tem) = gen_rtx_EXPR_LIST (REG_NONNEG, reg, - REG_NOTES (tem)); - } - bl->nonneg = 1; - } - - /* No insn may reference both the reversed and another biv or it - will fail (see comment near the top of the loop reversal - code). - Earlier on, we have verified that the biv has no use except - counting, or it is the only biv in this function. - However, the code that computes no_use_except_counting does - not verify reg notes. It's possible to have an insn that - references another biv, and has a REG_EQUAL note with an - expression based on the reversed biv. To avoid this case, - remove all REG_EQUAL notes based on the reversed biv - here. */ - for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) - if (INSN_P (p)) - { - rtx *pnote; - rtx set = single_set (p); - /* If this is a set of a GIV based on the reversed biv, any - REG_EQUAL notes should still be correct. */ - if (! set - || GET_CODE (SET_DEST (set)) != REG - || (size_t) REGNO (SET_DEST (set)) >= ivs->n_regs - || REG_IV_TYPE (ivs, REGNO (SET_DEST (set))) != GENERAL_INDUCT - || REG_IV_INFO (ivs, REGNO (SET_DEST (set)))->src_reg != bl->biv->src_reg) - for (pnote = ®_NOTES (p); *pnote;) - { - if (REG_NOTE_KIND (*pnote) == REG_EQUAL - && reg_mentioned_p (regno_reg_rtx[bl->regno], - XEXP (*pnote, 0))) - *pnote = XEXP (*pnote, 1); - else - pnote = &XEXP (*pnote, 1); - } - } - - /* Mark that this biv has been reversed. Each giv which depends - on this biv, and which is also live past the end of the loop - will have to be fixed up. */ - - bl->reversed = 1; - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "Reversed loop"); - if (bl->nonneg) - fprintf (loop_dump_stream, " and added reg_nonneg\n"); - else - fprintf (loop_dump_stream, "\n"); - } - - return 1; - } - } - } - - return 0; -} - -/* Verify whether the biv BL appears to be eliminable, - based on the insns in the loop that refer to it. - - If ELIMINATE_P is nonzero, actually do the elimination. - - THRESHOLD and INSN_COUNT are from loop_optimize and are used to - determine whether invariant insns should be placed inside or at the - start of the loop. */ - -static int -maybe_eliminate_biv (const struct loop *loop, struct iv_class *bl, - int eliminate_p, int threshold, int insn_count) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx reg = bl->biv->dest_reg; - rtx p; - - /* Scan all insns in the loop, stopping if we find one that uses the - biv in a way that we cannot eliminate. */ - - for (p = loop->start; p != loop->end; p = NEXT_INSN (p)) - { - enum rtx_code code = GET_CODE (p); - basic_block where_bb = 0; - rtx where_insn = threshold >= insn_count ? 0 : p; - rtx note; - - /* If this is a libcall that sets a giv, skip ahead to its end. */ - if (GET_RTX_CLASS (code) == 'i') - { - note = find_reg_note (p, REG_LIBCALL, NULL_RTX); - - if (note) - { - rtx last = XEXP (note, 0); - rtx set = single_set (last); - - if (set && GET_CODE (SET_DEST (set)) == REG) - { - unsigned int regno = REGNO (SET_DEST (set)); - - if (regno < ivs->n_regs - && REG_IV_TYPE (ivs, regno) == GENERAL_INDUCT - && REG_IV_INFO (ivs, regno)->src_reg == bl->biv->src_reg) - p = last; - } - } - } - - /* Closely examine the insn if the biv is mentioned. */ - if ((code == INSN || code == JUMP_INSN || code == CALL_INSN) - && reg_mentioned_p (reg, PATTERN (p)) - && ! maybe_eliminate_biv_1 (loop, PATTERN (p), p, bl, - eliminate_p, where_bb, where_insn)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Cannot eliminate biv %d: biv used in insn %d.\n", - bl->regno, INSN_UID (p)); - break; - } - - /* If we are eliminating, kill REG_EQUAL notes mentioning the biv. */ - if (eliminate_p - && (note = find_reg_note (p, REG_EQUAL, NULL_RTX)) != NULL_RTX - && reg_mentioned_p (reg, XEXP (note, 0))) - remove_note (p, note); - } - - if (p == loop->end) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "biv %d %s eliminated.\n", - bl->regno, eliminate_p ? "was" : "can be"); - return 1; - } - - return 0; -} - -/* INSN and REFERENCE are instructions in the same insn chain. - Return nonzero if INSN is first. */ - -int -loop_insn_first_p (rtx insn, rtx reference) -{ - rtx p, q; - - for (p = insn, q = reference;;) - { - /* Start with test for not first so that INSN == REFERENCE yields not - first. */ - if (q == insn || ! p) - return 0; - if (p == reference || ! q) - return 1; - - /* Either of P or Q might be a NOTE. Notes have the same LUID as the - previous insn, hence the <= comparison below does not work if - P is a note. */ - if (INSN_UID (p) < max_uid_for_loop - && INSN_UID (q) < max_uid_for_loop - && GET_CODE (p) != NOTE) - return INSN_LUID (p) <= INSN_LUID (q); - - if (INSN_UID (p) >= max_uid_for_loop - || GET_CODE (p) == NOTE) - p = NEXT_INSN (p); - if (INSN_UID (q) >= max_uid_for_loop) - q = NEXT_INSN (q); - } -} - -/* We are trying to eliminate BIV in INSN using GIV. Return nonzero if - the offset that we have to take into account due to auto-increment / - div derivation is zero. */ -static int -biv_elimination_giv_has_0_offset (struct induction *biv, - struct induction *giv, rtx insn) -{ - /* If the giv V had the auto-inc address optimization applied - to it, and INSN occurs between the giv insn and the biv - insn, then we'd have to adjust the value used here. - This is rare, so we don't bother to make this possible. */ - if (giv->auto_inc_opt - && ((loop_insn_first_p (giv->insn, insn) - && loop_insn_first_p (insn, biv->insn)) - || (loop_insn_first_p (biv->insn, insn) - && loop_insn_first_p (insn, giv->insn)))) - return 0; - - return 1; -} - -/* If BL appears in X (part of the pattern of INSN), see if we can - eliminate its use. If so, return 1. If not, return 0. - - If BIV does not appear in X, return 1. - - If ELIMINATE_P is nonzero, actually do the elimination. - WHERE_INSN/WHERE_BB indicate where extra insns should be added. - Depending on how many items have been moved out of the loop, it - will either be before INSN (when WHERE_INSN is nonzero) or at the - start of the loop (when WHERE_INSN is zero). */ - -static int -maybe_eliminate_biv_1 (const struct loop *loop, rtx x, rtx insn, - struct iv_class *bl, int eliminate_p, - basic_block where_bb, rtx where_insn) -{ - enum rtx_code code = GET_CODE (x); - rtx reg = bl->biv->dest_reg; - enum machine_mode mode = GET_MODE (reg); - struct induction *v; - rtx arg, tem; -#ifdef HAVE_cc0 - rtx new; -#endif - int arg_operand; - const char *fmt; - int i, j; - - switch (code) - { - case REG: - /* If we haven't already been able to do something with this BIV, - we can't eliminate it. */ - if (x == reg) - return 0; - return 1; - - case SET: - /* If this sets the BIV, it is not a problem. */ - if (SET_DEST (x) == reg) - return 1; - - /* If this is an insn that defines a giv, it is also ok because - it will go away when the giv is reduced. */ - for (v = bl->giv; v; v = v->next_iv) - if (v->giv_type == DEST_REG && SET_DEST (x) == v->dest_reg) - return 1; - -#ifdef HAVE_cc0 - if (SET_DEST (x) == cc0_rtx && SET_SRC (x) == reg) - { - /* Can replace with any giv that was reduced and - that has (MULT_VAL != 0) and (ADD_VAL == 0). - Require a constant for MULT_VAL, so we know it's nonzero. - ??? We disable this optimization to avoid potential - overflows. */ - - for (v = bl->giv; v; v = v->next_iv) - if (GET_CODE (v->mult_val) == CONST_INT && v->mult_val != const0_rtx - && v->add_val == const0_rtx - && ! v->ignore && ! v->maybe_dead && v->always_computable - && v->mode == mode - && 0) - { - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - if (! eliminate_p) - return 1; - - /* If the giv has the opposite direction of change, - then reverse the comparison. */ - if (INTVAL (v->mult_val) < 0) - new = gen_rtx_COMPARE (GET_MODE (v->new_reg), - const0_rtx, v->new_reg); - else - new = v->new_reg; - - /* We can probably test that giv's reduced reg. */ - if (validate_change (insn, &SET_SRC (x), new, 0)) - return 1; - } - - /* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0); - replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL). - Require a constant for MULT_VAL, so we know it's nonzero. - ??? Do this only if ADD_VAL is a pointer to avoid a potential - overflow problem. */ - - for (v = bl->giv; v; v = v->next_iv) - if (GET_CODE (v->mult_val) == CONST_INT - && v->mult_val != const0_rtx - && ! v->ignore && ! v->maybe_dead && v->always_computable - && v->mode == mode - && (GET_CODE (v->add_val) == SYMBOL_REF - || GET_CODE (v->add_val) == LABEL_REF - || GET_CODE (v->add_val) == CONST - || (GET_CODE (v->add_val) == REG - && REG_POINTER (v->add_val)))) - { - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - if (! eliminate_p) - return 1; - - /* If the giv has the opposite direction of change, - then reverse the comparison. */ - if (INTVAL (v->mult_val) < 0) - new = gen_rtx_COMPARE (VOIDmode, copy_rtx (v->add_val), - v->new_reg); - else - new = gen_rtx_COMPARE (VOIDmode, v->new_reg, - copy_rtx (v->add_val)); - - /* Replace biv with the giv's reduced register. */ - update_reg_last_use (v->add_val, insn); - if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0)) - return 1; - - /* Insn doesn't support that constant or invariant. Copy it - into a register (it will be a loop invariant.) */ - tem = gen_reg_rtx (GET_MODE (v->new_reg)); - - loop_insn_emit_before (loop, 0, where_insn, - gen_move_insn (tem, - copy_rtx (v->add_val))); - - /* Substitute the new register for its invariant value in - the compare expression. */ - XEXP (new, (INTVAL (v->mult_val) < 0) ? 0 : 1) = tem; - if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0)) - return 1; - } - } -#endif - break; - - case COMPARE: - case EQ: case NE: - case GT: case GE: case GTU: case GEU: - case LT: case LE: case LTU: case LEU: - /* See if either argument is the biv. */ - if (XEXP (x, 0) == reg) - arg = XEXP (x, 1), arg_operand = 1; - else if (XEXP (x, 1) == reg) - arg = XEXP (x, 0), arg_operand = 0; - else - break; - - if (CONSTANT_P (arg)) - { - /* First try to replace with any giv that has constant positive - mult_val and constant add_val. We might be able to support - negative mult_val, but it seems complex to do it in general. */ - - for (v = bl->giv; v; v = v->next_iv) - if (GET_CODE (v->mult_val) == CONST_INT - && INTVAL (v->mult_val) > 0 - && (GET_CODE (v->add_val) == SYMBOL_REF - || GET_CODE (v->add_val) == LABEL_REF - || GET_CODE (v->add_val) == CONST - || (GET_CODE (v->add_val) == REG - && REG_POINTER (v->add_val))) - && ! v->ignore && ! v->maybe_dead && v->always_computable - && v->mode == mode) - { - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - /* Don't eliminate if the linear combination that makes up - the giv overflows when it is applied to ARG. */ - if (GET_CODE (arg) == CONST_INT) - { - rtx add_val; - - if (GET_CODE (v->add_val) == CONST_INT) - add_val = v->add_val; - else - add_val = const0_rtx; - - if (const_mult_add_overflow_p (arg, v->mult_val, - add_val, mode, 1)) - continue; - } - - if (! eliminate_p) - return 1; - - /* Replace biv with the giv's reduced reg. */ - validate_change (insn, &XEXP (x, 1 - arg_operand), v->new_reg, 1); - - /* If all constants are actually constant integers and - the derived constant can be directly placed in the COMPARE, - do so. */ - if (GET_CODE (arg) == CONST_INT - && GET_CODE (v->add_val) == CONST_INT) - { - tem = expand_mult_add (arg, NULL_RTX, v->mult_val, - v->add_val, mode, 1); - } - else - { - /* Otherwise, load it into a register. */ - tem = gen_reg_rtx (mode); - loop_iv_add_mult_emit_before (loop, arg, - v->mult_val, v->add_val, - tem, where_bb, where_insn); - } - - validate_change (insn, &XEXP (x, arg_operand), tem, 1); - - if (apply_change_group ()) - return 1; - } - - /* Look for giv with positive constant mult_val and nonconst add_val. - Insert insns to calculate new compare value. - ??? Turn this off due to possible overflow. */ - - for (v = bl->giv; v; v = v->next_iv) - if (GET_CODE (v->mult_val) == CONST_INT - && INTVAL (v->mult_val) > 0 - && ! v->ignore && ! v->maybe_dead && v->always_computable - && v->mode == mode - && 0) - { - rtx tem; - - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - if (! eliminate_p) - return 1; - - tem = gen_reg_rtx (mode); - - /* Replace biv with giv's reduced register. */ - validate_change (insn, &XEXP (x, 1 - arg_operand), - v->new_reg, 1); - - /* Compute value to compare against. */ - loop_iv_add_mult_emit_before (loop, arg, - v->mult_val, v->add_val, - tem, where_bb, where_insn); - /* Use it in this insn. */ - validate_change (insn, &XEXP (x, arg_operand), tem, 1); - if (apply_change_group ()) - return 1; - } - } - else if (GET_CODE (arg) == REG || GET_CODE (arg) == MEM) - { - if (loop_invariant_p (loop, arg) == 1) - { - /* Look for giv with constant positive mult_val and nonconst - add_val. Insert insns to compute new compare value. - ??? Turn this off due to possible overflow. */ - - for (v = bl->giv; v; v = v->next_iv) - if (GET_CODE (v->mult_val) == CONST_INT && INTVAL (v->mult_val) > 0 - && ! v->ignore && ! v->maybe_dead && v->always_computable - && v->mode == mode - && 0) - { - rtx tem; - - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - if (! eliminate_p) - return 1; - - tem = gen_reg_rtx (mode); - - /* Replace biv with giv's reduced register. */ - validate_change (insn, &XEXP (x, 1 - arg_operand), - v->new_reg, 1); - - /* Compute value to compare against. */ - loop_iv_add_mult_emit_before (loop, arg, - v->mult_val, v->add_val, - tem, where_bb, where_insn); - validate_change (insn, &XEXP (x, arg_operand), tem, 1); - if (apply_change_group ()) - return 1; - } - } - - /* This code has problems. Basically, you can't know when - seeing if we will eliminate BL, whether a particular giv - of ARG will be reduced. If it isn't going to be reduced, - we can't eliminate BL. We can try forcing it to be reduced, - but that can generate poor code. - - The problem is that the benefit of reducing TV, below should - be increased if BL can actually be eliminated, but this means - we might have to do a topological sort of the order in which - we try to process biv. It doesn't seem worthwhile to do - this sort of thing now. */ - -#if 0 - /* Otherwise the reg compared with had better be a biv. */ - if (GET_CODE (arg) != REG - || REG_IV_TYPE (ivs, REGNO (arg)) != BASIC_INDUCT) - return 0; - - /* Look for a pair of givs, one for each biv, - with identical coefficients. */ - for (v = bl->giv; v; v = v->next_iv) - { - struct induction *tv; - - if (v->ignore || v->maybe_dead || v->mode != mode) - continue; - - for (tv = REG_IV_CLASS (ivs, REGNO (arg))->giv; tv; - tv = tv->next_iv) - if (! tv->ignore && ! tv->maybe_dead - && rtx_equal_p (tv->mult_val, v->mult_val) - && rtx_equal_p (tv->add_val, v->add_val) - && tv->mode == mode) - { - if (! biv_elimination_giv_has_0_offset (bl->biv, v, insn)) - continue; - - if (! eliminate_p) - return 1; - - /* Replace biv with its giv's reduced reg. */ - XEXP (x, 1 - arg_operand) = v->new_reg; - /* Replace other operand with the other giv's - reduced reg. */ - XEXP (x, arg_operand) = tv->new_reg; - return 1; - } - } -#endif - } - - /* If we get here, the biv can't be eliminated. */ - return 0; - - case MEM: - /* If this address is a DEST_ADDR giv, it doesn't matter if the - biv is used in it, since it will be replaced. */ - for (v = bl->giv; v; v = v->next_iv) - if (v->giv_type == DEST_ADDR && v->location == &XEXP (x, 0)) - return 1; - break; - - default: - break; - } - - /* See if any subexpression fails elimination. */ - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - switch (fmt[i]) - { - case 'e': - if (! maybe_eliminate_biv_1 (loop, XEXP (x, i), insn, bl, - eliminate_p, where_bb, where_insn)) - return 0; - break; - - case 'E': - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - if (! maybe_eliminate_biv_1 (loop, XVECEXP (x, i, j), insn, bl, - eliminate_p, where_bb, where_insn)) - return 0; - break; - } - } - - return 1; -} - -/* Return nonzero if the last use of REG - is in an insn following INSN in the same basic block. */ - -static int -last_use_this_basic_block (rtx reg, rtx insn) -{ - rtx n; - for (n = insn; - n && GET_CODE (n) != CODE_LABEL && GET_CODE (n) != JUMP_INSN; - n = NEXT_INSN (n)) - { - if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (n)) - return 1; - } - return 0; -} - -/* Called via `note_stores' to record the initial value of a biv. Here we - just record the location of the set and process it later. */ - -static void -record_initial (rtx dest, rtx set, void *data ATTRIBUTE_UNUSED) -{ - struct loop_ivs *ivs = (struct loop_ivs *) data; - struct iv_class *bl; - - if (GET_CODE (dest) != REG - || REGNO (dest) >= ivs->n_regs - || REG_IV_TYPE (ivs, REGNO (dest)) != BASIC_INDUCT) - return; - - bl = REG_IV_CLASS (ivs, REGNO (dest)); - - /* If this is the first set found, record it. */ - if (bl->init_insn == 0) - { - bl->init_insn = note_insn; - bl->init_set = set; - } -} - -/* If any of the registers in X are "old" and currently have a last use earlier - than INSN, update them to have a last use of INSN. Their actual last use - will be the previous insn but it will not have a valid uid_luid so we can't - use it. X must be a source expression only. */ - -static void -update_reg_last_use (rtx x, rtx insn) -{ - /* Check for the case where INSN does not have a valid luid. In this case, - there is no need to modify the regno_last_uid, as this can only happen - when code is inserted after the loop_end to set a pseudo's final value, - and hence this insn will never be the last use of x. - ???? This comment is not correct. See for example loop_givs_reduce. - This may insert an insn before another new insn. */ - if (GET_CODE (x) == REG && REGNO (x) < max_reg_before_loop - && INSN_UID (insn) < max_uid_for_loop - && REGNO_LAST_LUID (REGNO (x)) < INSN_LUID (insn)) - { - REGNO_LAST_UID (REGNO (x)) = INSN_UID (insn); - } - else - { - int i, j; - const char *fmt = GET_RTX_FORMAT (GET_CODE (x)); - for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - update_reg_last_use (XEXP (x, i), insn); - else if (fmt[i] == 'E') - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - update_reg_last_use (XVECEXP (x, i, j), insn); - } - } -} - -/* Given an insn INSN and condition COND, return the condition in a - canonical form to simplify testing by callers. Specifically: - - (1) The code will always be a comparison operation (EQ, NE, GT, etc.). - (2) Both operands will be machine operands; (cc0) will have been replaced. - (3) If an operand is a constant, it will be the second operand. - (4) (LE x const) will be replaced with (LT x <const+1>) and similarly - for GE, GEU, and LEU. - - If the condition cannot be understood, or is an inequality floating-point - comparison which needs to be reversed, 0 will be returned. - - If REVERSE is nonzero, then reverse the condition prior to canonizing it. - - If EARLIEST is nonzero, it is a pointer to a place where the earliest - insn used in locating the condition was found. If a replacement test - of the condition is desired, it should be placed in front of that - insn and we will be sure that the inputs are still valid. - - If WANT_REG is nonzero, we wish the condition to be relative to that - register, if possible. Therefore, do not canonicalize the condition - further. If ALLOW_CC_MODE is nonzero, allow the condition returned - to be a compare to a CC mode register. */ - -rtx -canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest, - rtx want_reg, int allow_cc_mode) -{ - enum rtx_code code; - rtx prev = insn; - rtx set; - rtx tem; - rtx op0, op1; - int reverse_code = 0; - enum machine_mode mode; - - code = GET_CODE (cond); - mode = GET_MODE (cond); - op0 = XEXP (cond, 0); - op1 = XEXP (cond, 1); - - if (reverse) - code = reversed_comparison_code (cond, insn); - if (code == UNKNOWN) - return 0; - - if (earliest) - *earliest = insn; - - /* If we are comparing a register with zero, see if the register is set - in the previous insn to a COMPARE or a comparison operation. Perform - the same tests as a function of STORE_FLAG_VALUE as find_comparison_args - in cse.c */ - - while (GET_RTX_CLASS (code) == '<' - && op1 == CONST0_RTX (GET_MODE (op0)) - && op0 != want_reg) - { - /* Set nonzero when we find something of interest. */ - rtx x = 0; - -#ifdef HAVE_cc0 - /* If comparison with cc0, import actual comparison from compare - insn. */ - if (op0 == cc0_rtx) - { - if ((prev = prev_nonnote_insn (prev)) == 0 - || GET_CODE (prev) != INSN - || (set = single_set (prev)) == 0 - || SET_DEST (set) != cc0_rtx) - return 0; - - op0 = SET_SRC (set); - op1 = CONST0_RTX (GET_MODE (op0)); - if (earliest) - *earliest = prev; - } -#endif - - /* If this is a COMPARE, pick up the two things being compared. */ - if (GET_CODE (op0) == COMPARE) - { - op1 = XEXP (op0, 1); - op0 = XEXP (op0, 0); - continue; - } - else if (GET_CODE (op0) != REG) - break; - - /* Go back to the previous insn. Stop if it is not an INSN. We also - stop if it isn't a single set or if it has a REG_INC note because - we don't want to bother dealing with it. */ - - if ((prev = prev_nonnote_insn (prev)) == 0 - || GET_CODE (prev) != INSN - || FIND_REG_INC_NOTE (prev, NULL_RTX)) - break; - - set = set_of (op0, prev); - - if (set - && (GET_CODE (set) != SET - || !rtx_equal_p (SET_DEST (set), op0))) - break; - - /* If this is setting OP0, get what it sets it to if it looks - relevant. */ - if (set) - { - enum machine_mode inner_mode = GET_MODE (SET_DEST (set)); -#ifdef FLOAT_STORE_FLAG_VALUE - REAL_VALUE_TYPE fsfv; -#endif - - /* ??? We may not combine comparisons done in a CCmode with - comparisons not done in a CCmode. This is to aid targets - like Alpha that have an IEEE compliant EQ instruction, and - a non-IEEE compliant BEQ instruction. The use of CCmode is - actually artificial, simply to prevent the combination, but - should not affect other platforms. - - However, we must allow VOIDmode comparisons to match either - CCmode or non-CCmode comparison, because some ports have - modeless comparisons inside branch patterns. - - ??? This mode check should perhaps look more like the mode check - in simplify_comparison in combine. */ - - if ((GET_CODE (SET_SRC (set)) == COMPARE - || (((code == NE - || (code == LT - && GET_MODE_CLASS (inner_mode) == MODE_INT - && (GET_MODE_BITSIZE (inner_mode) - <= HOST_BITS_PER_WIDE_INT) - && (STORE_FLAG_VALUE - & ((HOST_WIDE_INT) 1 - << (GET_MODE_BITSIZE (inner_mode) - 1)))) -#ifdef FLOAT_STORE_FLAG_VALUE - || (code == LT - && GET_MODE_CLASS (inner_mode) == MODE_FLOAT - && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode), - REAL_VALUE_NEGATIVE (fsfv))) -#endif - )) - && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<')) - && (((GET_MODE_CLASS (mode) == MODE_CC) - == (GET_MODE_CLASS (inner_mode) == MODE_CC)) - || mode == VOIDmode || inner_mode == VOIDmode)) - x = SET_SRC (set); - else if (((code == EQ - || (code == GE - && (GET_MODE_BITSIZE (inner_mode) - <= HOST_BITS_PER_WIDE_INT) - && GET_MODE_CLASS (inner_mode) == MODE_INT - && (STORE_FLAG_VALUE - & ((HOST_WIDE_INT) 1 - << (GET_MODE_BITSIZE (inner_mode) - 1)))) -#ifdef FLOAT_STORE_FLAG_VALUE - || (code == GE - && GET_MODE_CLASS (inner_mode) == MODE_FLOAT - && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode), - REAL_VALUE_NEGATIVE (fsfv))) -#endif - )) - && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<' - && (((GET_MODE_CLASS (mode) == MODE_CC) - == (GET_MODE_CLASS (inner_mode) == MODE_CC)) - || mode == VOIDmode || inner_mode == VOIDmode)) - - { - reverse_code = 1; - x = SET_SRC (set); - } - else - break; - } - - else if (reg_set_p (op0, prev)) - /* If this sets OP0, but not directly, we have to give up. */ - break; - - if (x) - { - if (GET_RTX_CLASS (GET_CODE (x)) == '<') - code = GET_CODE (x); - if (reverse_code) - { - code = reversed_comparison_code (x, prev); - if (code == UNKNOWN) - return 0; - reverse_code = 0; - } - - op0 = XEXP (x, 0), op1 = XEXP (x, 1); - if (earliest) - *earliest = prev; - } - } - - /* If constant is first, put it last. */ - if (CONSTANT_P (op0)) - code = swap_condition (code), tem = op0, op0 = op1, op1 = tem; - - /* If OP0 is the result of a comparison, we weren't able to find what - was really being compared, so fail. */ - if (!allow_cc_mode - && GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC) - return 0; - - /* Canonicalize any ordered comparison with integers involving equality - if we can do computations in the relevant mode and we do not - overflow. */ - - if (GET_MODE_CLASS (GET_MODE (op0)) != MODE_CC - && GET_CODE (op1) == CONST_INT - && GET_MODE (op0) != VOIDmode - && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT) - { - HOST_WIDE_INT const_val = INTVAL (op1); - unsigned HOST_WIDE_INT uconst_val = const_val; - unsigned HOST_WIDE_INT max_val - = (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0)); - - switch (code) - { - case LE: - if ((unsigned HOST_WIDE_INT) const_val != max_val >> 1) - code = LT, op1 = gen_int_mode (const_val + 1, GET_MODE (op0)); - break; - - /* When cross-compiling, const_val might be sign-extended from - BITS_PER_WORD to HOST_BITS_PER_WIDE_INT */ - case GE: - if ((HOST_WIDE_INT) (const_val & max_val) - != (((HOST_WIDE_INT) 1 - << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1)))) - code = GT, op1 = gen_int_mode (const_val - 1, GET_MODE (op0)); - break; - - case LEU: - if (uconst_val < max_val) - code = LTU, op1 = gen_int_mode (uconst_val + 1, GET_MODE (op0)); - break; - - case GEU: - if (uconst_val != 0) - code = GTU, op1 = gen_int_mode (uconst_val - 1, GET_MODE (op0)); - break; - - default: - break; - } - } - - /* Never return CC0; return zero instead. */ - if (CC0_P (op0)) - return 0; - - return gen_rtx_fmt_ee (code, VOIDmode, op0, op1); -} - -/* Given a jump insn JUMP, return the condition that will cause it to branch - to its JUMP_LABEL. If the condition cannot be understood, or is an - inequality floating-point comparison which needs to be reversed, 0 will - be returned. - - If EARLIEST is nonzero, it is a pointer to a place where the earliest - insn used in locating the condition was found. If a replacement test - of the condition is desired, it should be placed in front of that - insn and we will be sure that the inputs are still valid. - - If ALLOW_CC_MODE is nonzero, allow the condition returned to be a - compare CC mode register. */ - -rtx -get_condition (rtx jump, rtx *earliest, int allow_cc_mode) -{ - rtx cond; - int reverse; - rtx set; - - /* If this is not a standard conditional jump, we can't parse it. */ - if (GET_CODE (jump) != JUMP_INSN - || ! any_condjump_p (jump)) - return 0; - set = pc_set (jump); - - cond = XEXP (SET_SRC (set), 0); - - /* If this branches to JUMP_LABEL when the condition is false, reverse - the condition. */ - reverse - = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF - && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump); - - return canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX, - allow_cc_mode); -} - -/* Similar to above routine, except that we also put an invariant last - unless both operands are invariants. */ - -rtx -get_condition_for_loop (const struct loop *loop, rtx x) -{ - rtx comparison = get_condition (x, (rtx*) 0, false); - - if (comparison == 0 - || ! loop_invariant_p (loop, XEXP (comparison, 0)) - || loop_invariant_p (loop, XEXP (comparison, 1))) - return comparison; - - return gen_rtx_fmt_ee (swap_condition (GET_CODE (comparison)), VOIDmode, - XEXP (comparison, 1), XEXP (comparison, 0)); -} - -/* Scan the function and determine whether it has indirect (computed) jumps. - - This is taken mostly from flow.c; similar code exists elsewhere - in the compiler. It may be useful to put this into rtlanal.c. */ -static int -indirect_jump_in_function_p (rtx start) -{ - rtx insn; - - for (insn = start; insn; insn = NEXT_INSN (insn)) - if (computed_jump_p (insn)) - return 1; - - return 0; -} - -/* Add MEM to the LOOP_MEMS array, if appropriate. See the - documentation for LOOP_MEMS for the definition of `appropriate'. - This function is called from prescan_loop via for_each_rtx. */ - -static int -insert_loop_mem (rtx *mem, void *data ATTRIBUTE_UNUSED) -{ - struct loop_info *loop_info = data; - int i; - rtx m = *mem; - - if (m == NULL_RTX) - return 0; - - switch (GET_CODE (m)) - { - case MEM: - break; - - case CLOBBER: - /* We're not interested in MEMs that are only clobbered. */ - return -1; - - case CONST_DOUBLE: - /* We're not interested in the MEM associated with a - CONST_DOUBLE, so there's no need to traverse into this. */ - return -1; - - case EXPR_LIST: - /* We're not interested in any MEMs that only appear in notes. */ - return -1; - - default: - /* This is not a MEM. */ - return 0; - } - - /* See if we've already seen this MEM. */ - for (i = 0; i < loop_info->mems_idx; ++i) - if (rtx_equal_p (m, loop_info->mems[i].mem)) - { - if (MEM_VOLATILE_P (m) && !MEM_VOLATILE_P (loop_info->mems[i].mem)) - loop_info->mems[i].mem = m; - if (GET_MODE (m) != GET_MODE (loop_info->mems[i].mem)) - /* The modes of the two memory accesses are different. If - this happens, something tricky is going on, and we just - don't optimize accesses to this MEM. */ - loop_info->mems[i].optimize = 0; - - return 0; - } - - /* Resize the array, if necessary. */ - if (loop_info->mems_idx == loop_info->mems_allocated) - { - if (loop_info->mems_allocated != 0) - loop_info->mems_allocated *= 2; - else - loop_info->mems_allocated = 32; - - loop_info->mems = xrealloc (loop_info->mems, - loop_info->mems_allocated * sizeof (loop_mem_info)); - } - - /* Actually insert the MEM. */ - loop_info->mems[loop_info->mems_idx].mem = m; - /* We can't hoist this MEM out of the loop if it's a BLKmode MEM - because we can't put it in a register. We still store it in the - table, though, so that if we see the same address later, but in a - non-BLK mode, we'll not think we can optimize it at that point. */ - loop_info->mems[loop_info->mems_idx].optimize = (GET_MODE (m) != BLKmode); - loop_info->mems[loop_info->mems_idx].reg = NULL_RTX; - ++loop_info->mems_idx; - - return 0; -} - - -/* Allocate REGS->ARRAY or reallocate it if it is too small. - - Increment REGS->ARRAY[I].SET_IN_LOOP at the index I of each - register that is modified by an insn between FROM and TO. If the - value of an element of REGS->array[I].SET_IN_LOOP becomes 127 or - more, stop incrementing it, to avoid overflow. - - Store in REGS->ARRAY[I].SINGLE_USAGE the single insn in which - register I is used, if it is only used once. Otherwise, it is set - to 0 (for no uses) or const0_rtx for more than one use. This - parameter may be zero, in which case this processing is not done. - - Set REGS->ARRAY[I].MAY_NOT_OPTIMIZE nonzero if we should not - optimize register I. */ - -static void -loop_regs_scan (const struct loop *loop, int extra_size) -{ - struct loop_regs *regs = LOOP_REGS (loop); - int old_nregs; - /* last_set[n] is nonzero iff reg n has been set in the current - basic block. In that case, it is the insn that last set reg n. */ - rtx *last_set; - rtx insn; - int i; - - old_nregs = regs->num; - regs->num = max_reg_num (); - - /* Grow the regs array if not allocated or too small. */ - if (regs->num >= regs->size) - { - regs->size = regs->num + extra_size; - - regs->array = xrealloc (regs->array, regs->size * sizeof (*regs->array)); - - /* Zero the new elements. */ - memset (regs->array + old_nregs, 0, - (regs->size - old_nregs) * sizeof (*regs->array)); - } - - /* Clear previously scanned fields but do not clear n_times_set. */ - for (i = 0; i < old_nregs; i++) - { - regs->array[i].set_in_loop = 0; - regs->array[i].may_not_optimize = 0; - regs->array[i].single_usage = NULL_RTX; - } - - last_set = xcalloc (regs->num, sizeof (rtx)); - - /* Scan the loop, recording register usage. */ - for (insn = loop->top ? loop->top : loop->start; insn != loop->end; - insn = NEXT_INSN (insn)) - { - if (INSN_P (insn)) - { - /* Record registers that have exactly one use. */ - find_single_use_in_loop (regs, insn, PATTERN (insn)); - - /* Include uses in REG_EQUAL notes. */ - if (REG_NOTES (insn)) - find_single_use_in_loop (regs, insn, REG_NOTES (insn)); - - if (GET_CODE (PATTERN (insn)) == SET - || GET_CODE (PATTERN (insn)) == CLOBBER) - count_one_set (regs, insn, PATTERN (insn), last_set); - else if (GET_CODE (PATTERN (insn)) == PARALLEL) - { - int i; - for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) - count_one_set (regs, insn, XVECEXP (PATTERN (insn), 0, i), - last_set); - } - } - - if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN) - memset (last_set, 0, regs->num * sizeof (rtx)); - - /* Invalidate all registers used for function argument passing. - We check rtx_varies_p for the same reason as below, to allow - optimizing PIC calculations. */ - if (GET_CODE (insn) == CALL_INSN) - { - rtx link; - for (link = CALL_INSN_FUNCTION_USAGE (insn); - link; - link = XEXP (link, 1)) - { - rtx op, reg; - - if (GET_CODE (op = XEXP (link, 0)) == USE - && GET_CODE (reg = XEXP (op, 0)) == REG - && rtx_varies_p (reg, 1)) - regs->array[REGNO (reg)].may_not_optimize = 1; - } - } - } - - /* Invalidate all hard registers clobbered by calls. With one exception: - a call-clobbered PIC register is still function-invariant for our - purposes, since we can hoist any PIC calculations out of the loop. - Thus the call to rtx_varies_p. */ - if (LOOP_INFO (loop)->has_call) - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i) - && rtx_varies_p (regno_reg_rtx[i], 1)) - { - regs->array[i].may_not_optimize = 1; - regs->array[i].set_in_loop = 1; - } - -#ifdef AVOID_CCMODE_COPIES - /* Don't try to move insns which set CC registers if we should not - create CCmode register copies. */ - for (i = regs->num - 1; i >= FIRST_PSEUDO_REGISTER; i--) - if (GET_MODE_CLASS (GET_MODE (regno_reg_rtx[i])) == MODE_CC) - regs->array[i].may_not_optimize = 1; -#endif - - /* Set regs->array[I].n_times_set for the new registers. */ - for (i = old_nregs; i < regs->num; i++) - regs->array[i].n_times_set = regs->array[i].set_in_loop; - - free (last_set); -} - -/* Returns the number of real INSNs in the LOOP. */ - -static int -count_insns_in_loop (const struct loop *loop) -{ - int count = 0; - rtx insn; - - for (insn = loop->top ? loop->top : loop->start; insn != loop->end; - insn = NEXT_INSN (insn)) - if (INSN_P (insn)) - ++count; - - return count; -} - -/* Move MEMs into registers for the duration of the loop. */ - -static void -load_mems (const struct loop *loop) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_regs *regs = LOOP_REGS (loop); - int maybe_never = 0; - int i; - rtx p, prev_ebb_head; - rtx label = NULL_RTX; - rtx end_label; - /* Nonzero if the next instruction may never be executed. */ - int next_maybe_never = 0; - unsigned int last_max_reg = max_reg_num (); - - if (loop_info->mems_idx == 0) - return; - - /* We cannot use next_label here because it skips over normal insns. */ - end_label = next_nonnote_insn (loop->end); - if (end_label && GET_CODE (end_label) != CODE_LABEL) - end_label = NULL_RTX; - - /* Check to see if it's possible that some instructions in the loop are - never executed. Also check if there is a goto out of the loop other - than right after the end of the loop. */ - for (p = next_insn_in_loop (loop, loop->scan_start); - p != NULL_RTX; - p = next_insn_in_loop (loop, p)) - { - if (GET_CODE (p) == CODE_LABEL) - maybe_never = 1; - else if (GET_CODE (p) == JUMP_INSN - /* If we enter the loop in the middle, and scan - around to the beginning, don't set maybe_never - for that. This must be an unconditional jump, - otherwise the code at the top of the loop might - never be executed. Unconditional jumps are - followed a by barrier then loop end. */ - && ! (GET_CODE (p) == JUMP_INSN - && JUMP_LABEL (p) == loop->top - && NEXT_INSN (NEXT_INSN (p)) == loop->end - && any_uncondjump_p (p))) - { - /* If this is a jump outside of the loop but not right - after the end of the loop, we would have to emit new fixup - sequences for each such label. */ - if (/* If we can't tell where control might go when this - JUMP_INSN is executed, we must be conservative. */ - !JUMP_LABEL (p) - || (JUMP_LABEL (p) != end_label - && (INSN_UID (JUMP_LABEL (p)) >= max_uid_for_loop - || INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop->start) - || INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop->end)))) - return; - - if (!any_condjump_p (p)) - /* Something complicated. */ - maybe_never = 1; - else - /* If there are any more instructions in the loop, they - might not be reached. */ - next_maybe_never = 1; - } - else if (next_maybe_never) - maybe_never = 1; - } - - /* Find start of the extended basic block that enters the loop. */ - for (p = loop->start; - PREV_INSN (p) && GET_CODE (p) != CODE_LABEL; - p = PREV_INSN (p)) - ; - prev_ebb_head = p; - - cselib_init (); - - /* Build table of mems that get set to constant values before the - loop. */ - for (; p != loop->start; p = NEXT_INSN (p)) - cselib_process_insn (p); - - /* Actually move the MEMs. */ - for (i = 0; i < loop_info->mems_idx; ++i) - { - regset_head load_copies; - regset_head store_copies; - int written = 0; - rtx reg; - rtx mem = loop_info->mems[i].mem; - rtx mem_list_entry; - - if (MEM_VOLATILE_P (mem) - || loop_invariant_p (loop, XEXP (mem, 0)) != 1) - /* There's no telling whether or not MEM is modified. */ - loop_info->mems[i].optimize = 0; - - /* Go through the MEMs written to in the loop to see if this - one is aliased by one of them. */ - mem_list_entry = loop_info->store_mems; - while (mem_list_entry) - { - if (rtx_equal_p (mem, XEXP (mem_list_entry, 0))) - written = 1; - else if (true_dependence (XEXP (mem_list_entry, 0), VOIDmode, - mem, rtx_varies_p)) - { - /* MEM is indeed aliased by this store. */ - loop_info->mems[i].optimize = 0; - break; - } - mem_list_entry = XEXP (mem_list_entry, 1); - } - - if (flag_float_store && written - && GET_MODE_CLASS (GET_MODE (mem)) == MODE_FLOAT) - loop_info->mems[i].optimize = 0; - - /* If this MEM is written to, we must be sure that there - are no reads from another MEM that aliases this one. */ - if (loop_info->mems[i].optimize && written) - { - int j; - - for (j = 0; j < loop_info->mems_idx; ++j) - { - if (j == i) - continue; - else if (true_dependence (mem, - VOIDmode, - loop_info->mems[j].mem, - rtx_varies_p)) - { - /* It's not safe to hoist loop_info->mems[i] out of - the loop because writes to it might not be - seen by reads from loop_info->mems[j]. */ - loop_info->mems[i].optimize = 0; - break; - } - } - } - - if (maybe_never && may_trap_p (mem)) - /* We can't access the MEM outside the loop; it might - cause a trap that wouldn't have happened otherwise. */ - loop_info->mems[i].optimize = 0; - - if (!loop_info->mems[i].optimize) - /* We thought we were going to lift this MEM out of the - loop, but later discovered that we could not. */ - continue; - - INIT_REG_SET (&load_copies); - INIT_REG_SET (&store_copies); - - /* Allocate a pseudo for this MEM. We set REG_USERVAR_P in - order to keep scan_loop from moving stores to this MEM - out of the loop just because this REG is neither a - user-variable nor used in the loop test. */ - reg = gen_reg_rtx (GET_MODE (mem)); - REG_USERVAR_P (reg) = 1; - loop_info->mems[i].reg = reg; - - /* Now, replace all references to the MEM with the - corresponding pseudos. */ - maybe_never = 0; - for (p = next_insn_in_loop (loop, loop->scan_start); - p != NULL_RTX; - p = next_insn_in_loop (loop, p)) - { - if (INSN_P (p)) - { - rtx set; - - set = single_set (p); - - /* See if this copies the mem into a register that isn't - modified afterwards. We'll try to do copy propagation - a little further on. */ - if (set - /* @@@ This test is _way_ too conservative. */ - && ! maybe_never - && GET_CODE (SET_DEST (set)) == REG - && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER - && REGNO (SET_DEST (set)) < last_max_reg - && regs->array[REGNO (SET_DEST (set))].n_times_set == 1 - && rtx_equal_p (SET_SRC (set), mem)) - SET_REGNO_REG_SET (&load_copies, REGNO (SET_DEST (set))); - - /* See if this copies the mem from a register that isn't - modified afterwards. We'll try to remove the - redundant copy later on by doing a little register - renaming and copy propagation. This will help - to untangle things for the BIV detection code. */ - if (set - && ! maybe_never - && GET_CODE (SET_SRC (set)) == REG - && REGNO (SET_SRC (set)) >= FIRST_PSEUDO_REGISTER - && REGNO (SET_SRC (set)) < last_max_reg - && regs->array[REGNO (SET_SRC (set))].n_times_set == 1 - && rtx_equal_p (SET_DEST (set), mem)) - SET_REGNO_REG_SET (&store_copies, REGNO (SET_SRC (set))); - - /* If this is a call which uses / clobbers this memory - location, we must not change the interface here. */ - if (GET_CODE (p) == CALL_INSN - && reg_mentioned_p (loop_info->mems[i].mem, - CALL_INSN_FUNCTION_USAGE (p))) - { - cancel_changes (0); - loop_info->mems[i].optimize = 0; - break; - } - else - /* Replace the memory reference with the shadow register. */ - replace_loop_mems (p, loop_info->mems[i].mem, - loop_info->mems[i].reg, written); - } - - if (GET_CODE (p) == CODE_LABEL - || GET_CODE (p) == JUMP_INSN) - maybe_never = 1; - } - - if (! loop_info->mems[i].optimize) - ; /* We found we couldn't do the replacement, so do nothing. */ - else if (! apply_change_group ()) - /* We couldn't replace all occurrences of the MEM. */ - loop_info->mems[i].optimize = 0; - else - { - /* Load the memory immediately before LOOP->START, which is - the NOTE_LOOP_BEG. */ - cselib_val *e = cselib_lookup (mem, VOIDmode, 0); - rtx set; - rtx best = mem; - int j; - struct elt_loc_list *const_equiv = 0; - - if (e) - { - struct elt_loc_list *equiv; - struct elt_loc_list *best_equiv = 0; - for (equiv = e->locs; equiv; equiv = equiv->next) - { - if (CONSTANT_P (equiv->loc)) - const_equiv = equiv; - else if (GET_CODE (equiv->loc) == REG - /* Extending hard register lifetimes causes crash - on SRC targets. Doing so on non-SRC is - probably also not good idea, since we most - probably have pseudoregister equivalence as - well. */ - && REGNO (equiv->loc) >= FIRST_PSEUDO_REGISTER) - best_equiv = equiv; - } - /* Use the constant equivalence if that is cheap enough. */ - if (! best_equiv) - best_equiv = const_equiv; - else if (const_equiv - && (rtx_cost (const_equiv->loc, SET) - <= rtx_cost (best_equiv->loc, SET))) - { - best_equiv = const_equiv; - const_equiv = 0; - } - - /* If best_equiv is nonzero, we know that MEM is set to a - constant or register before the loop. We will use this - knowledge to initialize the shadow register with that - constant or reg rather than by loading from MEM. */ - if (best_equiv) - best = copy_rtx (best_equiv->loc); - } - - set = gen_move_insn (reg, best); - set = loop_insn_hoist (loop, set); - if (REG_P (best)) - { - for (p = prev_ebb_head; p != loop->start; p = NEXT_INSN (p)) - if (REGNO_LAST_UID (REGNO (best)) == INSN_UID (p)) - { - REGNO_LAST_UID (REGNO (best)) = INSN_UID (set); - break; - } - } - - if (const_equiv) - set_unique_reg_note (set, REG_EQUAL, copy_rtx (const_equiv->loc)); - - if (written) - { - if (label == NULL_RTX) - { - label = gen_label_rtx (); - emit_label_after (label, loop->end); - } - - /* Store the memory immediately after END, which is - the NOTE_LOOP_END. */ - set = gen_move_insn (copy_rtx (mem), reg); - loop_insn_emit_after (loop, 0, label, set); - } - - if (loop_dump_stream) - { - fprintf (loop_dump_stream, "Hoisted regno %d %s from ", - REGNO (reg), (written ? "r/w" : "r/o")); - print_rtl (loop_dump_stream, mem); - fputc ('\n', loop_dump_stream); - } - - /* Attempt a bit of copy propagation. This helps untangle the - data flow, and enables {basic,general}_induction_var to find - more bivs/givs. */ - EXECUTE_IF_SET_IN_REG_SET - (&load_copies, FIRST_PSEUDO_REGISTER, j, - { - try_copy_prop (loop, reg, j); - }); - CLEAR_REG_SET (&load_copies); - - EXECUTE_IF_SET_IN_REG_SET - (&store_copies, FIRST_PSEUDO_REGISTER, j, - { - try_swap_copy_prop (loop, reg, j); - }); - CLEAR_REG_SET (&store_copies); - } - } - - /* Now, we need to replace all references to the previous exit - label with the new one. */ - if (label != NULL_RTX && end_label != NULL_RTX) - for (p = loop->start; p != loop->end; p = NEXT_INSN (p)) - if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == end_label) - redirect_jump (p, label, false); - - cselib_finish (); -} - -/* For communication between note_reg_stored and its caller. */ -struct note_reg_stored_arg -{ - int set_seen; - rtx reg; -}; - -/* Called via note_stores, record in SET_SEEN whether X, which is written, - is equal to ARG. */ -static void -note_reg_stored (rtx x, rtx setter ATTRIBUTE_UNUSED, void *arg) -{ - struct note_reg_stored_arg *t = (struct note_reg_stored_arg *) arg; - if (t->reg == x) - t->set_seen = 1; -} - -/* Try to replace every occurrence of pseudo REGNO with REPLACEMENT. - There must be exactly one insn that sets this pseudo; it will be - deleted if all replacements succeed and we can prove that the register - is not used after the loop. */ - -static void -try_copy_prop (const struct loop *loop, rtx replacement, unsigned int regno) -{ - /* This is the reg that we are copying from. */ - rtx reg_rtx = regno_reg_rtx[regno]; - rtx init_insn = 0; - rtx insn; - /* These help keep track of whether we replaced all uses of the reg. */ - int replaced_last = 0; - int store_is_first = 0; - - for (insn = next_insn_in_loop (loop, loop->scan_start); - insn != NULL_RTX; - insn = next_insn_in_loop (loop, insn)) - { - rtx set; - - /* Only substitute within one extended basic block from the initializing - insn. */ - if (GET_CODE (insn) == CODE_LABEL && init_insn) - break; - - if (! INSN_P (insn)) - continue; - - /* Is this the initializing insn? */ - set = single_set (insn); - if (set - && GET_CODE (SET_DEST (set)) == REG - && REGNO (SET_DEST (set)) == regno) - { - if (init_insn) - abort (); - - init_insn = insn; - if (REGNO_FIRST_UID (regno) == INSN_UID (insn)) - store_is_first = 1; - } - - /* Only substitute after seeing the initializing insn. */ - if (init_insn && insn != init_insn) - { - struct note_reg_stored_arg arg; - - replace_loop_regs (insn, reg_rtx, replacement); - if (REGNO_LAST_UID (regno) == INSN_UID (insn)) - replaced_last = 1; - - /* Stop replacing when REPLACEMENT is modified. */ - arg.reg = replacement; - arg.set_seen = 0; - note_stores (PATTERN (insn), note_reg_stored, &arg); - if (arg.set_seen) - { - rtx note = find_reg_note (insn, REG_EQUAL, NULL); - - /* It is possible that we've turned previously valid REG_EQUAL to - invalid, as we change the REGNO to REPLACEMENT and unlike REGNO, - REPLACEMENT is modified, we get different meaning. */ - if (note && reg_mentioned_p (replacement, XEXP (note, 0))) - remove_note (insn, note); - break; - } - } - } - if (! init_insn) - abort (); - if (apply_change_group ()) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, " Replaced reg %d", regno); - if (store_is_first && replaced_last) - { - rtx first; - rtx retval_note; - - /* Assume we're just deleting INIT_INSN. */ - first = init_insn; - /* Look for REG_RETVAL note. If we're deleting the end of - the libcall sequence, the whole sequence can go. */ - retval_note = find_reg_note (init_insn, REG_RETVAL, NULL_RTX); - /* If we found a REG_RETVAL note, find the first instruction - in the sequence. */ - if (retval_note) - first = XEXP (retval_note, 0); - - /* Delete the instructions. */ - loop_delete_insns (first, init_insn); - } - if (loop_dump_stream) - fprintf (loop_dump_stream, ".\n"); - } -} - -/* Replace all the instructions from FIRST up to and including LAST - with NOTE_INSN_DELETED notes. */ - -static void -loop_delete_insns (rtx first, rtx last) -{ - while (1) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, ", deleting init_insn (%d)", - INSN_UID (first)); - delete_insn (first); - - /* If this was the LAST instructions we're supposed to delete, - we're done. */ - if (first == last) - break; - - first = NEXT_INSN (first); - } -} - -/* Try to replace occurrences of pseudo REGNO with REPLACEMENT within - loop LOOP if the order of the sets of these registers can be - swapped. There must be exactly one insn within the loop that sets - this pseudo followed immediately by a move insn that sets - REPLACEMENT with REGNO. */ -static void -try_swap_copy_prop (const struct loop *loop, rtx replacement, - unsigned int regno) -{ - rtx insn; - rtx set = NULL_RTX; - unsigned int new_regno; - - new_regno = REGNO (replacement); - - for (insn = next_insn_in_loop (loop, loop->scan_start); - insn != NULL_RTX; - insn = next_insn_in_loop (loop, insn)) - { - /* Search for the insn that copies REGNO to NEW_REGNO? */ - if (INSN_P (insn) - && (set = single_set (insn)) - && GET_CODE (SET_DEST (set)) == REG - && REGNO (SET_DEST (set)) == new_regno - && GET_CODE (SET_SRC (set)) == REG - && REGNO (SET_SRC (set)) == regno) - break; - } - - if (insn != NULL_RTX) - { - rtx prev_insn; - rtx prev_set; - - /* Some DEF-USE info would come in handy here to make this - function more general. For now, just check the previous insn - which is the most likely candidate for setting REGNO. */ - - prev_insn = PREV_INSN (insn); - - if (INSN_P (insn) - && (prev_set = single_set (prev_insn)) - && GET_CODE (SET_DEST (prev_set)) == REG - && REGNO (SET_DEST (prev_set)) == regno) - { - /* We have: - (set (reg regno) (expr)) - (set (reg new_regno) (reg regno)) - - so try converting this to: - (set (reg new_regno) (expr)) - (set (reg regno) (reg new_regno)) - - The former construct is often generated when a global - variable used for an induction variable is shadowed by a - register (NEW_REGNO). The latter construct improves the - chances of GIV replacement and BIV elimination. */ - - validate_change (prev_insn, &SET_DEST (prev_set), - replacement, 1); - validate_change (insn, &SET_DEST (set), - SET_SRC (set), 1); - validate_change (insn, &SET_SRC (set), - replacement, 1); - - if (apply_change_group ()) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - " Swapped set of reg %d at %d with reg %d at %d.\n", - regno, INSN_UID (insn), - new_regno, INSN_UID (prev_insn)); - - /* Update first use of REGNO. */ - if (REGNO_FIRST_UID (regno) == INSN_UID (prev_insn)) - REGNO_FIRST_UID (regno) = INSN_UID (insn); - - /* Now perform copy propagation to hopefully - remove all uses of REGNO within the loop. */ - try_copy_prop (loop, replacement, regno); - } - } - } -} - -/* Worker function for find_mem_in_note, called via for_each_rtx. */ - -static int -find_mem_in_note_1 (rtx *x, void *data) -{ - if (*x != NULL_RTX && GET_CODE (*x) == MEM) - { - rtx *res = (rtx *) data; - *res = *x; - return 1; - } - return 0; -} - -/* Returns the first MEM found in NOTE by depth-first search. */ - -static rtx -find_mem_in_note (rtx note) -{ - if (note && for_each_rtx (¬e, find_mem_in_note_1, ¬e)) - return note; - return NULL_RTX; -} - -/* Replace MEM with its associated pseudo register. This function is - called from load_mems via for_each_rtx. DATA is actually a pointer - to a structure describing the instruction currently being scanned - and the MEM we are currently replacing. */ - -static int -replace_loop_mem (rtx *mem, void *data) -{ - loop_replace_args *args = (loop_replace_args *) data; - rtx m = *mem; - - if (m == NULL_RTX) - return 0; - - switch (GET_CODE (m)) - { - case MEM: - break; - - case CONST_DOUBLE: - /* We're not interested in the MEM associated with a - CONST_DOUBLE, so there's no need to traverse into one. */ - return -1; - - default: - /* This is not a MEM. */ - return 0; - } - - if (!rtx_equal_p (args->match, m)) - /* This is not the MEM we are currently replacing. */ - return 0; - - /* Actually replace the MEM. */ - validate_change (args->insn, mem, args->replacement, 1); - - return 0; -} - -static void -replace_loop_mems (rtx insn, rtx mem, rtx reg, int written) -{ - loop_replace_args args; - - args.insn = insn; - args.match = mem; - args.replacement = reg; - - for_each_rtx (&insn, replace_loop_mem, &args); - - /* If we hoist a mem write out of the loop, then REG_EQUAL - notes referring to the mem are no longer valid. */ - if (written) - { - rtx note, sub; - rtx *link; - - for (link = ®_NOTES (insn); (note = *link); link = &XEXP (note, 1)) - { - if (REG_NOTE_KIND (note) == REG_EQUAL - && (sub = find_mem_in_note (note)) - && true_dependence (mem, VOIDmode, sub, rtx_varies_p)) - { - /* Remove the note. */ - validate_change (NULL_RTX, link, XEXP (note, 1), 1); - break; - } - } - } -} - -/* Replace one register with another. Called through for_each_rtx; PX points - to the rtx being scanned. DATA is actually a pointer to - a structure of arguments. */ - -static int -replace_loop_reg (rtx *px, void *data) -{ - rtx x = *px; - loop_replace_args *args = (loop_replace_args *) data; - - if (x == NULL_RTX) - return 0; - - if (x == args->match) - validate_change (args->insn, px, args->replacement, 1); - - return 0; -} - -static void -replace_loop_regs (rtx insn, rtx reg, rtx replacement) -{ - loop_replace_args args; - - args.insn = insn; - args.match = reg; - args.replacement = replacement; - - for_each_rtx (&insn, replace_loop_reg, &args); -} - -/* Emit insn for PATTERN after WHERE_INSN in basic block WHERE_BB - (ignored in the interim). */ - -static rtx -loop_insn_emit_after (const struct loop *loop ATTRIBUTE_UNUSED, - basic_block where_bb ATTRIBUTE_UNUSED, rtx where_insn, - rtx pattern) -{ - return emit_insn_after (pattern, where_insn); -} - - -/* If WHERE_INSN is nonzero emit insn for PATTERN before WHERE_INSN - in basic block WHERE_BB (ignored in the interim) within the loop - otherwise hoist PATTERN into the loop pre-header. */ - -rtx -loop_insn_emit_before (const struct loop *loop, - basic_block where_bb ATTRIBUTE_UNUSED, - rtx where_insn, rtx pattern) -{ - if (! where_insn) - return loop_insn_hoist (loop, pattern); - return emit_insn_before (pattern, where_insn); -} - - -/* Emit call insn for PATTERN before WHERE_INSN in basic block - WHERE_BB (ignored in the interim) within the loop. */ - -static rtx -loop_call_insn_emit_before (const struct loop *loop ATTRIBUTE_UNUSED, - basic_block where_bb ATTRIBUTE_UNUSED, - rtx where_insn, rtx pattern) -{ - return emit_call_insn_before (pattern, where_insn); -} - - -/* Hoist insn for PATTERN into the loop pre-header. */ - -rtx -loop_insn_hoist (const struct loop *loop, rtx pattern) -{ - return loop_insn_emit_before (loop, 0, loop->start, pattern); -} - - -/* Hoist call insn for PATTERN into the loop pre-header. */ - -static rtx -loop_call_insn_hoist (const struct loop *loop, rtx pattern) -{ - return loop_call_insn_emit_before (loop, 0, loop->start, pattern); -} - - -/* Sink insn for PATTERN after the loop end. */ - -rtx -loop_insn_sink (const struct loop *loop, rtx pattern) -{ - return loop_insn_emit_before (loop, 0, loop->sink, pattern); -} - -/* bl->final_value can be either general_operand or PLUS of general_operand - and constant. Emit sequence of instructions to load it into REG. */ -static rtx -gen_load_of_final_value (rtx reg, rtx final_value) -{ - rtx seq; - start_sequence (); - final_value = force_operand (final_value, reg); - if (final_value != reg) - emit_move_insn (reg, final_value); - seq = get_insns (); - end_sequence (); - return seq; -} - -/* If the loop has multiple exits, emit insn for PATTERN before the - loop to ensure that it will always be executed no matter how the - loop exits. Otherwise, emit the insn for PATTERN after the loop, - since this is slightly more efficient. */ - -static rtx -loop_insn_sink_or_swim (const struct loop *loop, rtx pattern) -{ - if (loop->exit_count) - return loop_insn_hoist (loop, pattern); - else - return loop_insn_sink (loop, pattern); -} - -static void -loop_ivs_dump (const struct loop *loop, FILE *file, int verbose) -{ - struct iv_class *bl; - int iv_num = 0; - - if (! loop || ! file) - return; - - for (bl = LOOP_IVS (loop)->list; bl; bl = bl->next) - iv_num++; - - fprintf (file, "Loop %d: %d IV classes\n", loop->num, iv_num); - - for (bl = LOOP_IVS (loop)->list; bl; bl = bl->next) - { - loop_iv_class_dump (bl, file, verbose); - fputc ('\n', file); - } -} - - -static void -loop_iv_class_dump (const struct iv_class *bl, FILE *file, - int verbose ATTRIBUTE_UNUSED) -{ - struct induction *v; - rtx incr; - int i; - - if (! bl || ! file) - return; - - fprintf (file, "IV class for reg %d, benefit %d\n", - bl->regno, bl->total_benefit); - - fprintf (file, " Init insn %d", INSN_UID (bl->init_insn)); - if (bl->initial_value) - { - fprintf (file, ", init val: "); - print_simple_rtl (file, bl->initial_value); - } - if (bl->initial_test) - { - fprintf (file, ", init test: "); - print_simple_rtl (file, bl->initial_test); - } - fputc ('\n', file); - - if (bl->final_value) - { - fprintf (file, " Final val: "); - print_simple_rtl (file, bl->final_value); - fputc ('\n', file); - } - - if ((incr = biv_total_increment (bl))) - { - fprintf (file, " Total increment: "); - print_simple_rtl (file, incr); - fputc ('\n', file); - } - - /* List the increments. */ - for (i = 0, v = bl->biv; v; v = v->next_iv, i++) - { - fprintf (file, " Inc%d: insn %d, incr: ", i, INSN_UID (v->insn)); - print_simple_rtl (file, v->add_val); - fputc ('\n', file); - } - - /* List the givs. */ - for (i = 0, v = bl->giv; v; v = v->next_iv, i++) - { - fprintf (file, " Giv%d: insn %d, benefit %d, ", - i, INSN_UID (v->insn), v->benefit); - if (v->giv_type == DEST_ADDR) - print_simple_rtl (file, v->mem); - else - print_simple_rtl (file, single_set (v->insn)); - fputc ('\n', file); - } -} - - -static void -loop_biv_dump (const struct induction *v, FILE *file, int verbose) -{ - if (! v || ! file) - return; - - fprintf (file, - "Biv %d: insn %d", - REGNO (v->dest_reg), INSN_UID (v->insn)); - fprintf (file, " const "); - print_simple_rtl (file, v->add_val); - - if (verbose && v->final_value) - { - fputc ('\n', file); - fprintf (file, " final "); - print_simple_rtl (file, v->final_value); - } - - fputc ('\n', file); -} - - -static void -loop_giv_dump (const struct induction *v, FILE *file, int verbose) -{ - if (! v || ! file) - return; - - if (v->giv_type == DEST_REG) - fprintf (file, "Giv %d: insn %d", - REGNO (v->dest_reg), INSN_UID (v->insn)); - else - fprintf (file, "Dest address: insn %d", - INSN_UID (v->insn)); - - fprintf (file, " src reg %d benefit %d", - REGNO (v->src_reg), v->benefit); - fprintf (file, " lifetime %d", - v->lifetime); - - if (v->replaceable) - fprintf (file, " replaceable"); - - if (v->no_const_addval) - fprintf (file, " ncav"); - - if (v->ext_dependent) - { - switch (GET_CODE (v->ext_dependent)) - { - case SIGN_EXTEND: - fprintf (file, " ext se"); - break; - case ZERO_EXTEND: - fprintf (file, " ext ze"); - break; - case TRUNCATE: - fprintf (file, " ext tr"); - break; - default: - abort (); - } - } - - fputc ('\n', file); - fprintf (file, " mult "); - print_simple_rtl (file, v->mult_val); - - fputc ('\n', file); - fprintf (file, " add "); - print_simple_rtl (file, v->add_val); - - if (verbose && v->final_value) - { - fputc ('\n', file); - fprintf (file, " final "); - print_simple_rtl (file, v->final_value); - } - - fputc ('\n', file); -} - - -void -debug_ivs (const struct loop *loop) -{ - loop_ivs_dump (loop, stderr, 1); -} - - -void -debug_iv_class (const struct iv_class *bl) -{ - loop_iv_class_dump (bl, stderr, 1); -} - - -void -debug_biv (const struct induction *v) -{ - loop_biv_dump (v, stderr, 1); -} - - -void -debug_giv (const struct induction *v) -{ - loop_giv_dump (v, stderr, 1); -} - - -#define LOOP_BLOCK_NUM_1(INSN) \ -((INSN) ? (BLOCK_FOR_INSN (INSN) ? BLOCK_NUM (INSN) : - 1) : -1) - -/* The notes do not have an assigned block, so look at the next insn. */ -#define LOOP_BLOCK_NUM(INSN) \ -((INSN) ? (GET_CODE (INSN) == NOTE \ - ? LOOP_BLOCK_NUM_1 (next_nonnote_insn (INSN)) \ - : LOOP_BLOCK_NUM_1 (INSN)) \ - : -1) - -#define LOOP_INSN_UID(INSN) ((INSN) ? INSN_UID (INSN) : -1) - -static void -loop_dump_aux (const struct loop *loop, FILE *file, - int verbose ATTRIBUTE_UNUSED) -{ - rtx label; - - if (! loop || ! file) - return; - - /* Print diagnostics to compare our concept of a loop with - what the loop notes say. */ - if (! PREV_INSN (BB_HEAD (loop->first)) - || GET_CODE (PREV_INSN (BB_HEAD (loop->first))) != NOTE - || NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (loop->first))) - != NOTE_INSN_LOOP_BEG) - fprintf (file, ";; No NOTE_INSN_LOOP_BEG at %d\n", - INSN_UID (PREV_INSN (BB_HEAD (loop->first)))); - if (! NEXT_INSN (BB_END (loop->last)) - || GET_CODE (NEXT_INSN (BB_END (loop->last))) != NOTE - || NOTE_LINE_NUMBER (NEXT_INSN (BB_END (loop->last))) - != NOTE_INSN_LOOP_END) - fprintf (file, ";; No NOTE_INSN_LOOP_END at %d\n", - INSN_UID (NEXT_INSN (BB_END (loop->last)))); - - if (loop->start) - { - fprintf (file, - ";; start %d (%d), cont dom %d (%d), cont %d (%d), vtop %d (%d), end %d (%d)\n", - LOOP_BLOCK_NUM (loop->start), - LOOP_INSN_UID (loop->start), - LOOP_BLOCK_NUM (loop->cont), - LOOP_INSN_UID (loop->cont), - LOOP_BLOCK_NUM (loop->cont), - LOOP_INSN_UID (loop->cont), - LOOP_BLOCK_NUM (loop->vtop), - LOOP_INSN_UID (loop->vtop), - LOOP_BLOCK_NUM (loop->end), - LOOP_INSN_UID (loop->end)); - fprintf (file, ";; top %d (%d), scan start %d (%d)\n", - LOOP_BLOCK_NUM (loop->top), - LOOP_INSN_UID (loop->top), - LOOP_BLOCK_NUM (loop->scan_start), - LOOP_INSN_UID (loop->scan_start)); - fprintf (file, ";; exit_count %d", loop->exit_count); - if (loop->exit_count) - { - fputs (", labels:", file); - for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label)) - { - fprintf (file, " %d ", - LOOP_INSN_UID (XEXP (label, 0))); - } - } - fputs ("\n", file); - - /* This can happen when a marked loop appears as two nested loops, - say from while (a || b) {}. The inner loop won't match - the loop markers but the outer one will. */ - if (LOOP_BLOCK_NUM (loop->cont) != loop->latch->index) - fprintf (file, ";; NOTE_INSN_LOOP_CONT not in loop latch\n"); - } -} - -/* Call this function from the debugger to dump LOOP. */ - -void -debug_loop (const struct loop *loop) -{ - flow_loop_dump (loop, stderr, loop_dump_aux, 1); -} - -/* Call this function from the debugger to dump LOOPS. */ - -void -debug_loops (const struct loops *loops) -{ - flow_loops_dump (loops, stderr, loop_dump_aux, 1); -} |
