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Diffstat (limited to 'gcc/sched-ebb.c')
| -rw-r--r-- | gcc/sched-ebb.c | 775 |
1 files changed, 775 insertions, 0 deletions
diff --git a/gcc/sched-ebb.c b/gcc/sched-ebb.c new file mode 100644 index 0000000..b2e82b5 --- /dev/null +++ b/gcc/sched-ebb.c @@ -0,0 +1,775 @@ +/* Instruction scheduling pass. + Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, + 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. + Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by, + and currently maintained by, Jim Wilson (wilson@cygnus.com) + +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, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "toplev.h" +#include "rtl.h" +#include "tm_p.h" +#include "hard-reg-set.h" +#include "regs.h" +#include "function.h" +#include "flags.h" +#include "insn-config.h" +#include "insn-attr.h" +#include "except.h" +#include "toplev.h" +#include "recog.h" +#include "cfglayout.h" +#include "params.h" +#include "sched-int.h" +#include "target.h" +#include "output.h" + +/* The number of insns scheduled so far. */ +static int sched_n_insns; + +/* The number of insns to be scheduled in total. */ +static int n_insns; + +/* Set of blocks, that already have their dependencies calculated. */ +static bitmap_head dont_calc_deps; +/* Set of basic blocks, that are ebb heads of tails respectively. */ +static bitmap_head ebb_head, ebb_tail; + +/* Last basic block in current ebb. */ +static basic_block last_bb; + +/* Implementations of the sched_info functions for region scheduling. */ +static void init_ready_list (void); +static void begin_schedule_ready (rtx, rtx); +static int schedule_more_p (void); +static const char *ebb_print_insn (rtx, int); +static int rank (rtx, rtx); +static int contributes_to_priority (rtx, rtx); +static void compute_jump_reg_dependencies (rtx, regset, regset, regset); +static basic_block earliest_block_with_similiar_load (basic_block, rtx); +static void add_deps_for_risky_insns (rtx, rtx); +static basic_block schedule_ebb (rtx, rtx); + +static void add_remove_insn (rtx, int); +static void add_block1 (basic_block, basic_block); +static basic_block advance_target_bb (basic_block, rtx); +static void fix_recovery_cfg (int, int, int); + +#ifdef ENABLE_CHECKING +static int ebb_head_or_leaf_p (basic_block, int); +#endif + +/* Return nonzero if there are more insns that should be scheduled. */ + +static int +schedule_more_p (void) +{ + return sched_n_insns < n_insns; +} + +/* Add all insns that are initially ready to the ready list READY. Called + once before scheduling a set of insns. */ + +static void +init_ready_list (void) +{ + int n = 0; + rtx prev_head = current_sched_info->prev_head; + rtx next_tail = current_sched_info->next_tail; + rtx insn; + + sched_n_insns = 0; + +#if 0 + /* Print debugging information. */ + if (sched_verbose >= 5) + debug_dependencies (); +#endif + + /* Initialize ready list with all 'ready' insns in target block. + Count number of insns in the target block being scheduled. */ + for (insn = NEXT_INSN (prev_head); insn != next_tail; insn = NEXT_INSN (insn)) + { + try_ready (insn); + n++; + } + + gcc_assert (n == n_insns); +} + +/* INSN is being scheduled after LAST. Update counters. */ +static void +begin_schedule_ready (rtx insn, rtx last) +{ + sched_n_insns++; + + if (BLOCK_FOR_INSN (insn) == last_bb + /* INSN is a jump in the last block, ... */ + && control_flow_insn_p (insn) + /* that is going to be moved over some instructions. */ + && last != PREV_INSN (insn)) + { + edge e; + edge_iterator ei; + basic_block bb; + + /* An obscure special case, where we do have partially dead + instruction scheduled after last control flow instruction. + In this case we can create new basic block. It is + always exactly one basic block last in the sequence. */ + + FOR_EACH_EDGE (e, ei, last_bb->succs) + if (e->flags & EDGE_FALLTHRU) + break; + +#ifdef ENABLE_CHECKING + gcc_assert (!e || !(e->flags & EDGE_COMPLEX)); + + gcc_assert (BLOCK_FOR_INSN (insn) == last_bb + && !IS_SPECULATION_CHECK_P (insn) + && BB_HEAD (last_bb) != insn + && BB_END (last_bb) == insn); + + { + rtx x; + + x = NEXT_INSN (insn); + if (e) + gcc_assert (NOTE_P (x) || LABEL_P (x)); + else + gcc_assert (BARRIER_P (x)); + } +#endif + + if (e) + { + bb = split_edge (e); + gcc_assert (NOTE_INSN_BASIC_BLOCK_P (BB_END (bb))); + } + else + /* Create an empty unreachable block after the INSN. */ + bb = create_basic_block (NEXT_INSN (insn), NULL_RTX, last_bb); + + /* split_edge () creates BB before E->DEST. Keep in mind, that + this operation extends scheduling region till the end of BB. + Hence, we need to shift NEXT_TAIL, so haifa-sched.c won't go out + of the scheduling region. */ + current_sched_info->next_tail = NEXT_INSN (BB_END (bb)); + gcc_assert (current_sched_info->next_tail); + + add_block (bb, last_bb); + gcc_assert (last_bb == bb); + } +} + +/* Return a string that contains the insn uid and optionally anything else + necessary to identify this insn in an output. It's valid to use a + static buffer for this. The ALIGNED parameter should cause the string + to be formatted so that multiple output lines will line up nicely. */ + +static const char * +ebb_print_insn (rtx insn, int aligned ATTRIBUTE_UNUSED) +{ + static char tmp[80]; + + sprintf (tmp, "%4d", INSN_UID (insn)); + return tmp; +} + +/* Compare priority of two insns. Return a positive number if the second + insn is to be preferred for scheduling, and a negative one if the first + is to be preferred. Zero if they are equally good. */ + +static int +rank (rtx insn1, rtx insn2) +{ + basic_block bb1 = BLOCK_FOR_INSN (insn1); + basic_block bb2 = BLOCK_FOR_INSN (insn2); + + if (bb1->count > bb2->count + || bb1->frequency > bb2->frequency) + return -1; + if (bb1->count < bb2->count + || bb1->frequency < bb2->frequency) + return 1; + return 0; +} + +/* NEXT is an instruction that depends on INSN (a backward dependence); + return nonzero if we should include this dependence in priority + calculations. */ + +static int +contributes_to_priority (rtx next ATTRIBUTE_UNUSED, + rtx insn ATTRIBUTE_UNUSED) +{ + return 1; +} + + /* INSN is a JUMP_INSN, COND_SET is the set of registers that are + conditionally set before INSN. Store the set of registers that + must be considered as used by this jump in USED and that of + registers that must be considered as set in SET. */ + +static void +compute_jump_reg_dependencies (rtx insn, regset cond_set, regset used, + regset set) +{ + basic_block b = BLOCK_FOR_INSN (insn); + edge e; + edge_iterator ei; + + FOR_EACH_EDGE (e, ei, b->succs) + if (e->flags & EDGE_FALLTHRU) + /* The jump may be a by-product of a branch that has been merged + in the main codepath after being conditionalized. Therefore + it may guard the fallthrough block from using a value that has + conditionally overwritten that of the main codepath. So we + consider that it restores the value of the main codepath. */ + bitmap_and (set, glat_start [e->dest->index], cond_set); + else + bitmap_ior_into (used, glat_start [e->dest->index]); +} + +/* Used in schedule_insns to initialize current_sched_info for scheduling + regions (or single basic blocks). */ + +static struct sched_info ebb_sched_info = +{ + init_ready_list, + NULL, + schedule_more_p, + NULL, + rank, + ebb_print_insn, + contributes_to_priority, + compute_jump_reg_dependencies, + + NULL, NULL, + NULL, NULL, + 0, 1, 0, + + add_remove_insn, + begin_schedule_ready, + add_block1, + advance_target_bb, + fix_recovery_cfg, +#ifdef ENABLE_CHECKING + ebb_head_or_leaf_p, +#endif + /* We need to DETACH_LIVE_INFO to be able to create new basic blocks. + See begin_schedule_ready (). */ + SCHED_EBB | USE_GLAT | DETACH_LIFE_INFO +}; + +/* Returns the earliest block in EBB currently being processed where a + "similar load" 'insn2' is found, and hence LOAD_INSN can move + speculatively into the found block. All the following must hold: + + (1) both loads have 1 base register (PFREE_CANDIDATEs). + (2) load_insn and load2 have a def-use dependence upon + the same insn 'insn1'. + + From all these we can conclude that the two loads access memory + addresses that differ at most by a constant, and hence if moving + load_insn would cause an exception, it would have been caused by + load2 anyhow. + + The function uses list (given by LAST_BLOCK) of already processed + blocks in EBB. The list is formed in `add_deps_for_risky_insns'. */ + +static basic_block +earliest_block_with_similiar_load (basic_block last_block, rtx load_insn) +{ + rtx back_link; + basic_block bb, earliest_block = NULL; + + for (back_link = LOG_LINKS (load_insn); + back_link; + back_link = XEXP (back_link, 1)) + { + rtx insn1 = XEXP (back_link, 0); + + if (GET_MODE (back_link) == VOIDmode) + { + /* Found a DEF-USE dependence (insn1, load_insn). */ + rtx fore_link; + + for (fore_link = INSN_DEPEND (insn1); + fore_link; + fore_link = XEXP (fore_link, 1)) + { + rtx insn2 = XEXP (fore_link, 0); + basic_block insn2_block = BLOCK_FOR_INSN (insn2); + + if (GET_MODE (fore_link) == VOIDmode) + { + if (earliest_block != NULL + && earliest_block->index < insn2_block->index) + continue; + + /* Found a DEF-USE dependence (insn1, insn2). */ + if (haifa_classify_insn (insn2) != PFREE_CANDIDATE) + /* insn2 not guaranteed to be a 1 base reg load. */ + continue; + + for (bb = last_block; bb; bb = bb->aux) + if (insn2_block == bb) + break; + + if (!bb) + /* insn2 is the similar load. */ + earliest_block = insn2_block; + } + } + } + } + + return earliest_block; +} + +/* The following function adds dependencies between jumps and risky + insns in given ebb. */ + +static void +add_deps_for_risky_insns (rtx head, rtx tail) +{ + rtx insn, prev; + int class; + rtx last_jump = NULL_RTX; + rtx next_tail = NEXT_INSN (tail); + basic_block last_block = NULL, bb; + + for (insn = head; insn != next_tail; insn = NEXT_INSN (insn)) + if (control_flow_insn_p (insn)) + { + bb = BLOCK_FOR_INSN (insn); + bb->aux = last_block; + last_block = bb; + last_jump = insn; + } + else if (INSN_P (insn) && last_jump != NULL_RTX) + { + class = haifa_classify_insn (insn); + prev = last_jump; + switch (class) + { + case PFREE_CANDIDATE: + if (flag_schedule_speculative_load) + { + bb = earliest_block_with_similiar_load (last_block, insn); + if (bb) + { + bb = bb->aux; + if (!bb) + break; + prev = BB_END (bb); + } + } + /* Fall through. */ + case TRAP_RISKY: + case IRISKY: + case PRISKY_CANDIDATE: + /* ??? We could implement better checking PRISKY_CANDIDATEs + analogous to sched-rgn.c. */ + /* We can not change the mode of the backward + dependency because REG_DEP_ANTI has the lowest + rank. */ + if (! sched_insns_conditions_mutex_p (insn, prev)) + { + if (!(current_sched_info->flags & DO_SPECULATION)) + { + enum DEPS_ADJUST_RESULT res; + + res = add_or_update_back_dep (insn, prev, + REG_DEP_ANTI, DEP_ANTI); + + if (res == DEP_CREATED) + add_forw_dep (insn, LOG_LINKS (insn)); + else + gcc_assert (res != DEP_CHANGED); + } + else + add_or_update_back_forw_dep (insn, prev, REG_DEP_ANTI, + set_dep_weak (DEP_ANTI, + BEGIN_CONTROL, + MAX_DEP_WEAK)); + } + + break; + + default: + break; + } + } + /* Maintain the invariant that bb->aux is clear after use. */ + while (last_block) + { + bb = last_block->aux; + last_block->aux = NULL; + last_block = bb; + } +} + +/* Schedule a single extended basic block, defined by the boundaries HEAD + and TAIL. */ + +static basic_block +schedule_ebb (rtx head, rtx tail) +{ + basic_block first_bb, target_bb; + struct deps tmp_deps; + + first_bb = BLOCK_FOR_INSN (head); + last_bb = BLOCK_FOR_INSN (tail); + + if (no_real_insns_p (head, tail)) + return BLOCK_FOR_INSN (tail); + + gcc_assert (INSN_P (head) && INSN_P (tail)); + + if (!bitmap_bit_p (&dont_calc_deps, first_bb->index)) + { + init_deps_global (); + + /* Compute LOG_LINKS. */ + init_deps (&tmp_deps); + sched_analyze (&tmp_deps, head, tail); + free_deps (&tmp_deps); + + /* Compute INSN_DEPEND. */ + compute_forward_dependences (head, tail); + + add_deps_for_risky_insns (head, tail); + + if (targetm.sched.dependencies_evaluation_hook) + targetm.sched.dependencies_evaluation_hook (head, tail); + + finish_deps_global (); + } + else + /* Only recovery blocks can have their dependencies already calculated, + and they always are single block ebbs. */ + gcc_assert (first_bb == last_bb); + + /* Set priorities. */ + current_sched_info->sched_max_insns_priority = 0; + n_insns = set_priorities (head, tail); + current_sched_info->sched_max_insns_priority++; + + current_sched_info->prev_head = PREV_INSN (head); + current_sched_info->next_tail = NEXT_INSN (tail); + + if (write_symbols != NO_DEBUG) + { + save_line_notes (first_bb->index, head, tail); + rm_line_notes (head, tail); + } + + /* rm_other_notes only removes notes which are _inside_ the + block---that is, it won't remove notes before the first real insn + or after the last real insn of the block. So if the first insn + has a REG_SAVE_NOTE which would otherwise be emitted before the + insn, it is redundant with the note before the start of the + block, and so we have to take it out. */ + if (INSN_P (head)) + { + rtx note; + + for (note = REG_NOTES (head); note; note = XEXP (note, 1)) + if (REG_NOTE_KIND (note) == REG_SAVE_NOTE) + remove_note (head, note); + } + + /* Remove remaining note insns from the block, save them in + note_list. These notes are restored at the end of + schedule_block (). */ + rm_other_notes (head, tail); + + unlink_bb_notes (first_bb, last_bb); + + current_sched_info->queue_must_finish_empty = 1; + + target_bb = first_bb; + schedule_block (&target_bb, n_insns); + + /* We might pack all instructions into fewer blocks, + so we may made some of them empty. Can't assert (b == last_bb). */ + + /* Sanity check: verify that all region insns were scheduled. */ + gcc_assert (sched_n_insns == n_insns); + head = current_sched_info->head; + tail = current_sched_info->tail; + + if (write_symbols != NO_DEBUG) + restore_line_notes (head, tail); + + if (EDGE_COUNT (last_bb->preds) == 0) + /* LAST_BB is unreachable. */ + { + gcc_assert (first_bb != last_bb + && EDGE_COUNT (last_bb->succs) == 0); + last_bb = last_bb->prev_bb; + delete_basic_block (last_bb->next_bb); + } + + return last_bb; +} + +/* The one entry point in this file. */ + +void +schedule_ebbs (void) +{ + basic_block bb; + int probability_cutoff; + rtx tail; + sbitmap large_region_blocks, blocks; + int any_large_regions; + + if (profile_info && flag_branch_probabilities) + probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK); + else + probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY); + probability_cutoff = REG_BR_PROB_BASE / 100 * probability_cutoff; + + /* Taking care of this degenerate case makes the rest of + this code simpler. */ + if (n_basic_blocks == NUM_FIXED_BLOCKS) + return; + + /* We need current_sched_info in init_dependency_caches, which is + invoked via sched_init. */ + current_sched_info = &ebb_sched_info; + + sched_init (); + + compute_bb_for_insn (); + + /* Initialize DONT_CALC_DEPS and ebb-{start, end} markers. */ + bitmap_initialize (&dont_calc_deps, 0); + bitmap_clear (&dont_calc_deps); + bitmap_initialize (&ebb_head, 0); + bitmap_clear (&ebb_head); + bitmap_initialize (&ebb_tail, 0); + bitmap_clear (&ebb_tail); + + /* Schedule every region in the subroutine. */ + FOR_EACH_BB (bb) + { + rtx head = BB_HEAD (bb); + + for (;;) + { + edge e; + edge_iterator ei; + tail = BB_END (bb); + if (bb->next_bb == EXIT_BLOCK_PTR + || LABEL_P (BB_HEAD (bb->next_bb))) + break; + FOR_EACH_EDGE (e, ei, bb->succs) + if ((e->flags & EDGE_FALLTHRU) != 0) + break; + if (! e) + break; + if (e->probability <= probability_cutoff) + break; + bb = bb->next_bb; + } + + /* Blah. We should fix the rest of the code not to get confused by + a note or two. */ + while (head != tail) + { + if (NOTE_P (head)) + head = NEXT_INSN (head); + else if (NOTE_P (tail)) + tail = PREV_INSN (tail); + else if (LABEL_P (head)) + head = NEXT_INSN (head); + else + break; + } + + bitmap_set_bit (&ebb_head, BLOCK_NUM (head)); + bb = schedule_ebb (head, tail); + bitmap_set_bit (&ebb_tail, bb->index); + } + bitmap_clear (&dont_calc_deps); + + gcc_assert (current_sched_info->flags & DETACH_LIFE_INFO); + /* We can create new basic blocks during scheduling, and + attach_life_info () will create regsets for them + (along with attaching existing info back). */ + attach_life_info (); + + /* Updating register live information. */ + allocate_reg_life_data (); + + any_large_regions = 0; + large_region_blocks = sbitmap_alloc (last_basic_block); + sbitmap_zero (large_region_blocks); + FOR_EACH_BB (bb) + SET_BIT (large_region_blocks, bb->index); + + blocks = sbitmap_alloc (last_basic_block); + sbitmap_zero (blocks); + + /* Update life information. For regions consisting of multiple blocks + we've possibly done interblock scheduling that affects global liveness. + For regions consisting of single blocks we need to do only local + liveness. */ + FOR_EACH_BB (bb) + { + int bbi; + + bbi = bb->index; + + if (!bitmap_bit_p (&ebb_head, bbi) + || !bitmap_bit_p (&ebb_tail, bbi) + /* New blocks (e.g. recovery blocks) should be processed + as parts of large regions. */ + || !glat_start[bbi]) + any_large_regions = 1; + else + { + SET_BIT (blocks, bbi); + RESET_BIT (large_region_blocks, bbi); + } + } + + update_life_info (blocks, UPDATE_LIFE_LOCAL, 0); + sbitmap_free (blocks); + + if (any_large_regions) + { + update_life_info (large_region_blocks, UPDATE_LIFE_GLOBAL, 0); + +#ifdef ENABLE_CHECKING + /* !!! We can't check reg_live_info here because of the fact, + that destination registers of COND_EXEC's may be dead + before scheduling (while they should be alive). Don't know why. */ + /*check_reg_live (true);*/ +#endif + } + sbitmap_free (large_region_blocks); + + bitmap_clear (&ebb_head); + bitmap_clear (&ebb_tail); + + /* Reposition the prologue and epilogue notes in case we moved the + prologue/epilogue insns. */ + if (reload_completed) + reposition_prologue_and_epilogue_notes (get_insns ()); + + if (write_symbols != NO_DEBUG) + rm_redundant_line_notes (); + + sched_finish (); +} + +/* INSN has been added to/removed from current ebb. */ +static void +add_remove_insn (rtx insn ATTRIBUTE_UNUSED, int remove_p) +{ + if (!remove_p) + n_insns++; + else + n_insns--; +} + +/* BB was added to ebb after AFTER. */ +static void +add_block1 (basic_block bb, basic_block after) +{ + /* Recovery blocks are always bounded by BARRIERS, + therefore, they always form single block EBB, + therefore, we can use rec->index to identify such EBBs. */ + if (after == EXIT_BLOCK_PTR) + bitmap_set_bit (&dont_calc_deps, bb->index); + else if (after == last_bb) + last_bb = bb; +} + +/* Return next block in ebb chain. For parameter meaning please refer to + sched-int.h: struct sched_info: advance_target_bb. */ +static basic_block +advance_target_bb (basic_block bb, rtx insn) +{ + if (insn) + { + if (BLOCK_FOR_INSN (insn) != bb + && control_flow_insn_p (insn) + /* We handle interblock movement of the speculation check + or over a speculation check in + haifa-sched.c: move_block_after_check (). */ + && !IS_SPECULATION_BRANCHY_CHECK_P (insn) + && !IS_SPECULATION_BRANCHY_CHECK_P (BB_END (bb))) + { + /* Assert that we don't move jumps across blocks. */ + gcc_assert (!control_flow_insn_p (BB_END (bb)) + && NOTE_INSN_BASIC_BLOCK_P (BB_HEAD (bb->next_bb))); + return bb; + } + else + return 0; + } + else + /* Return next non empty block. */ + { + do + { + gcc_assert (bb != last_bb); + + bb = bb->next_bb; + } + while (bb_note (bb) == BB_END (bb)); + + return bb; + } +} + +/* Fix internal data after interblock movement of jump instruction. + For parameter meaning please refer to + sched-int.h: struct sched_info: fix_recovery_cfg. */ +static void +fix_recovery_cfg (int bbi ATTRIBUTE_UNUSED, int jump_bbi, int jump_bb_nexti) +{ + gcc_assert (last_bb->index != bbi); + + if (jump_bb_nexti == last_bb->index) + last_bb = BASIC_BLOCK (jump_bbi); +} + +#ifdef ENABLE_CHECKING +/* Return non zero, if BB is first or last (depending of LEAF_P) block in + current ebb. For more information please refer to + sched-int.h: struct sched_info: region_head_or_leaf_p. */ +static int +ebb_head_or_leaf_p (basic_block bb, int leaf_p) +{ + if (!leaf_p) + return bitmap_bit_p (&ebb_head, bb->index); + else + return bitmap_bit_p (&ebb_tail, bb->index); +} +#endif /* ENABLE_CHECKING */ |
