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Diffstat (limited to 'contrib/gcc/cselib.c')
| -rw-r--r-- | contrib/gcc/cselib.c | 1519 |
1 files changed, 1519 insertions, 0 deletions
diff --git a/contrib/gcc/cselib.c b/contrib/gcc/cselib.c new file mode 100644 index 0000000..4070da7 --- /dev/null +++ b/contrib/gcc/cselib.c @@ -0,0 +1,1519 @@ +/* Common subexpression elimination library for GNU compiler. + Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, + 1999, 2000, 2001, 2003, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" + +#include "rtl.h" +#include "tm_p.h" +#include "regs.h" +#include "hard-reg-set.h" +#include "flags.h" +#include "real.h" +#include "insn-config.h" +#include "recog.h" +#include "function.h" +#include "emit-rtl.h" +#include "toplev.h" +#include "output.h" +#include "ggc.h" +#include "hashtab.h" +#include "cselib.h" +#include "params.h" +#include "alloc-pool.h" +#include "target.h" + +static bool cselib_record_memory; +static int entry_and_rtx_equal_p (const void *, const void *); +static hashval_t get_value_hash (const void *); +static struct elt_list *new_elt_list (struct elt_list *, cselib_val *); +static struct elt_loc_list *new_elt_loc_list (struct elt_loc_list *, rtx); +static void unchain_one_value (cselib_val *); +static void unchain_one_elt_list (struct elt_list **); +static void unchain_one_elt_loc_list (struct elt_loc_list **); +static int discard_useless_locs (void **, void *); +static int discard_useless_values (void **, void *); +static void remove_useless_values (void); +static rtx wrap_constant (enum machine_mode, rtx); +static unsigned int cselib_hash_rtx (rtx, int); +static cselib_val *new_cselib_val (unsigned int, enum machine_mode); +static void add_mem_for_addr (cselib_val *, cselib_val *, rtx); +static cselib_val *cselib_lookup_mem (rtx, int); +static void cselib_invalidate_regno (unsigned int, enum machine_mode); +static void cselib_invalidate_mem (rtx); +static void cselib_record_set (rtx, cselib_val *, cselib_val *); +static void cselib_record_sets (rtx); + +/* There are three ways in which cselib can look up an rtx: + - for a REG, the reg_values table (which is indexed by regno) is used + - for a MEM, we recursively look up its address and then follow the + addr_list of that value + - for everything else, we compute a hash value and go through the hash + table. Since different rtx's can still have the same hash value, + this involves walking the table entries for a given value and comparing + the locations of the entries with the rtx we are looking up. */ + +/* A table that enables us to look up elts by their value. */ +static htab_t cselib_hash_table; + +/* This is a global so we don't have to pass this through every function. + It is used in new_elt_loc_list to set SETTING_INSN. */ +static rtx cselib_current_insn; +static bool cselib_current_insn_in_libcall; + +/* Every new unknown value gets a unique number. */ +static unsigned int next_unknown_value; + +/* The number of registers we had when the varrays were last resized. */ +static unsigned int cselib_nregs; + +/* Count values without known locations. Whenever this grows too big, we + remove these useless values from the table. */ +static int n_useless_values; + +/* Number of useless values before we remove them from the hash table. */ +#define MAX_USELESS_VALUES 32 + +/* This table maps from register number to values. It does not + contain pointers to cselib_val structures, but rather elt_lists. + The purpose is to be able to refer to the same register in + different modes. The first element of the list defines the mode in + which the register was set; if the mode is unknown or the value is + no longer valid in that mode, ELT will be NULL for the first + element. */ +static struct elt_list **reg_values; +static unsigned int reg_values_size; +#define REG_VALUES(i) reg_values[i] + +/* The largest number of hard regs used by any entry added to the + REG_VALUES table. Cleared on each cselib_clear_table() invocation. */ +static unsigned int max_value_regs; + +/* Here the set of indices I with REG_VALUES(I) != 0 is saved. This is used + in cselib_clear_table() for fast emptying. */ +static unsigned int *used_regs; +static unsigned int n_used_regs; + +/* We pass this to cselib_invalidate_mem to invalidate all of + memory for a non-const call instruction. */ +static GTY(()) rtx callmem; + +/* Set by discard_useless_locs if it deleted the last location of any + value. */ +static int values_became_useless; + +/* Used as stop element of the containing_mem list so we can check + presence in the list by checking the next pointer. */ +static cselib_val dummy_val; + +/* Used to list all values that contain memory reference. + May or may not contain the useless values - the list is compacted + each time memory is invalidated. */ +static cselib_val *first_containing_mem = &dummy_val; +static alloc_pool elt_loc_list_pool, elt_list_pool, cselib_val_pool, value_pool; + + +/* Allocate a struct elt_list and fill in its two elements with the + arguments. */ + +static inline struct elt_list * +new_elt_list (struct elt_list *next, cselib_val *elt) +{ + struct elt_list *el; + el = pool_alloc (elt_list_pool); + el->next = next; + el->elt = elt; + return el; +} + +/* Allocate a struct elt_loc_list and fill in its two elements with the + arguments. */ + +static inline struct elt_loc_list * +new_elt_loc_list (struct elt_loc_list *next, rtx loc) +{ + struct elt_loc_list *el; + el = pool_alloc (elt_loc_list_pool); + el->next = next; + el->loc = loc; + el->setting_insn = cselib_current_insn; + el->in_libcall = cselib_current_insn_in_libcall; + return el; +} + +/* The elt_list at *PL is no longer needed. Unchain it and free its + storage. */ + +static inline void +unchain_one_elt_list (struct elt_list **pl) +{ + struct elt_list *l = *pl; + + *pl = l->next; + pool_free (elt_list_pool, l); +} + +/* Likewise for elt_loc_lists. */ + +static void +unchain_one_elt_loc_list (struct elt_loc_list **pl) +{ + struct elt_loc_list *l = *pl; + + *pl = l->next; + pool_free (elt_loc_list_pool, l); +} + +/* Likewise for cselib_vals. This also frees the addr_list associated with + V. */ + +static void +unchain_one_value (cselib_val *v) +{ + while (v->addr_list) + unchain_one_elt_list (&v->addr_list); + + pool_free (cselib_val_pool, v); +} + +/* Remove all entries from the hash table. Also used during + initialization. If CLEAR_ALL isn't set, then only clear the entries + which are known to have been used. */ + +void +cselib_clear_table (void) +{ + unsigned int i; + + for (i = 0; i < n_used_regs; i++) + REG_VALUES (used_regs[i]) = 0; + + max_value_regs = 0; + + n_used_regs = 0; + + htab_empty (cselib_hash_table); + + n_useless_values = 0; + + next_unknown_value = 0; + + first_containing_mem = &dummy_val; +} + +/* The equality test for our hash table. The first argument ENTRY is a table + element (i.e. a cselib_val), while the second arg X is an rtx. We know + that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a + CONST of an appropriate mode. */ + +static int +entry_and_rtx_equal_p (const void *entry, const void *x_arg) +{ + struct elt_loc_list *l; + const cselib_val *v = (const cselib_val *) entry; + rtx x = (rtx) x_arg; + enum machine_mode mode = GET_MODE (x); + + gcc_assert (GET_CODE (x) != CONST_INT + && (mode != VOIDmode || GET_CODE (x) != CONST_DOUBLE)); + + if (mode != GET_MODE (v->u.val_rtx)) + return 0; + + /* Unwrap X if necessary. */ + if (GET_CODE (x) == CONST + && (GET_CODE (XEXP (x, 0)) == CONST_INT + || GET_CODE (XEXP (x, 0)) == CONST_DOUBLE)) + x = XEXP (x, 0); + + /* We don't guarantee that distinct rtx's have different hash values, + so we need to do a comparison. */ + for (l = v->locs; l; l = l->next) + if (rtx_equal_for_cselib_p (l->loc, x)) + return 1; + + return 0; +} + +/* The hash function for our hash table. The value is always computed with + cselib_hash_rtx when adding an element; this function just extracts the + hash value from a cselib_val structure. */ + +static hashval_t +get_value_hash (const void *entry) +{ + const cselib_val *v = (const cselib_val *) entry; + return v->value; +} + +/* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we + only return true for values which point to a cselib_val whose value + element has been set to zero, which implies the cselib_val will be + removed. */ + +int +references_value_p (rtx x, int only_useless) +{ + enum rtx_code code = GET_CODE (x); + const char *fmt = GET_RTX_FORMAT (code); + int i, j; + + if (GET_CODE (x) == VALUE + && (! only_useless || CSELIB_VAL_PTR (x)->locs == 0)) + return 1; + + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless)) + return 1; + else if (fmt[i] == 'E') + for (j = 0; j < XVECLEN (x, i); j++) + if (references_value_p (XVECEXP (x, i, j), only_useless)) + return 1; + } + + return 0; +} + +/* For all locations found in X, delete locations that reference useless + values (i.e. values without any location). Called through + htab_traverse. */ + +static int +discard_useless_locs (void **x, void *info ATTRIBUTE_UNUSED) +{ + cselib_val *v = (cselib_val *)*x; + struct elt_loc_list **p = &v->locs; + int had_locs = v->locs != 0; + + while (*p) + { + if (references_value_p ((*p)->loc, 1)) + unchain_one_elt_loc_list (p); + else + p = &(*p)->next; + } + + if (had_locs && v->locs == 0) + { + n_useless_values++; + values_became_useless = 1; + } + return 1; +} + +/* If X is a value with no locations, remove it from the hashtable. */ + +static int +discard_useless_values (void **x, void *info ATTRIBUTE_UNUSED) +{ + cselib_val *v = (cselib_val *)*x; + + if (v->locs == 0) + { + CSELIB_VAL_PTR (v->u.val_rtx) = NULL; + htab_clear_slot (cselib_hash_table, x); + unchain_one_value (v); + n_useless_values--; + } + + return 1; +} + +/* Clean out useless values (i.e. those which no longer have locations + associated with them) from the hash table. */ + +static void +remove_useless_values (void) +{ + cselib_val **p, *v; + /* First pass: eliminate locations that reference the value. That in + turn can make more values useless. */ + do + { + values_became_useless = 0; + htab_traverse (cselib_hash_table, discard_useless_locs, 0); + } + while (values_became_useless); + + /* Second pass: actually remove the values. */ + + p = &first_containing_mem; + for (v = *p; v != &dummy_val; v = v->next_containing_mem) + if (v->locs) + { + *p = v; + p = &(*p)->next_containing_mem; + } + *p = &dummy_val; + + htab_traverse (cselib_hash_table, discard_useless_values, 0); + + gcc_assert (!n_useless_values); +} + +/* Return the mode in which a register was last set. If X is not a + register, return its mode. If the mode in which the register was + set is not known, or the value was already clobbered, return + VOIDmode. */ + +enum machine_mode +cselib_reg_set_mode (rtx x) +{ + if (!REG_P (x)) + return GET_MODE (x); + + if (REG_VALUES (REGNO (x)) == NULL + || REG_VALUES (REGNO (x))->elt == NULL) + return VOIDmode; + + return GET_MODE (REG_VALUES (REGNO (x))->elt->u.val_rtx); +} + +/* Return nonzero if we can prove that X and Y contain the same value, taking + our gathered information into account. */ + +int +rtx_equal_for_cselib_p (rtx x, rtx y) +{ + enum rtx_code code; + const char *fmt; + int i; + + if (REG_P (x) || MEM_P (x)) + { + cselib_val *e = cselib_lookup (x, GET_MODE (x), 0); + + if (e) + x = e->u.val_rtx; + } + + if (REG_P (y) || MEM_P (y)) + { + cselib_val *e = cselib_lookup (y, GET_MODE (y), 0); + + if (e) + y = e->u.val_rtx; + } + + if (x == y) + return 1; + + if (GET_CODE (x) == VALUE && GET_CODE (y) == VALUE) + return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y); + + if (GET_CODE (x) == VALUE) + { + cselib_val *e = CSELIB_VAL_PTR (x); + struct elt_loc_list *l; + + for (l = e->locs; l; l = l->next) + { + rtx t = l->loc; + + /* Avoid infinite recursion. */ + if (REG_P (t) || MEM_P (t)) + continue; + else if (rtx_equal_for_cselib_p (t, y)) + return 1; + } + + return 0; + } + + if (GET_CODE (y) == VALUE) + { + cselib_val *e = CSELIB_VAL_PTR (y); + struct elt_loc_list *l; + + for (l = e->locs; l; l = l->next) + { + rtx t = l->loc; + + if (REG_P (t) || MEM_P (t)) + continue; + else if (rtx_equal_for_cselib_p (x, t)) + return 1; + } + + return 0; + } + + if (GET_CODE (x) != GET_CODE (y) || GET_MODE (x) != GET_MODE (y)) + return 0; + + /* These won't be handled correctly by the code below. */ + switch (GET_CODE (x)) + { + case CONST_DOUBLE: + return 0; + + case LABEL_REF: + return XEXP (x, 0) == XEXP (y, 0); + + default: + break; + } + + code = GET_CODE (x); + fmt = GET_RTX_FORMAT (code); + + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + int j; + + switch (fmt[i]) + { + case 'w': + if (XWINT (x, i) != XWINT (y, i)) + return 0; + break; + + case 'n': + case 'i': + if (XINT (x, i) != XINT (y, i)) + return 0; + break; + + case 'V': + 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_cselib_p (XVECEXP (x, i, j), + XVECEXP (y, i, j))) + return 0; + break; + + case 'e': + if (i == 1 + && targetm.commutative_p (x, UNKNOWN) + && rtx_equal_for_cselib_p (XEXP (x, 1), XEXP (y, 0)) + && rtx_equal_for_cselib_p (XEXP (x, 0), XEXP (y, 1))) + return 1; + if (! rtx_equal_for_cselib_p (XEXP (x, i), XEXP (y, i))) + return 0; + break; + + case 'S': + 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': + case 't': + 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: + gcc_unreachable (); + } + } + return 1; +} + +/* We need to pass down the mode of constants through the hash table + functions. For that purpose, wrap them in a CONST of the appropriate + mode. */ +static rtx +wrap_constant (enum machine_mode mode, rtx x) +{ + if (GET_CODE (x) != CONST_INT + && (GET_CODE (x) != CONST_DOUBLE || GET_MODE (x) != VOIDmode)) + return x; + gcc_assert (mode != VOIDmode); + return gen_rtx_CONST (mode, x); +} + +/* Hash an rtx. Return 0 if we couldn't hash the rtx. + For registers and memory locations, we look up their cselib_val structure + and return its VALUE element. + Possible reasons for return 0 are: the object is volatile, or we couldn't + find a register or memory location in the table and CREATE is zero. If + CREATE is nonzero, table elts are created for regs and mem. + N.B. this hash function returns the same hash value for RTXes that + differ only in the order of operands, thus it is suitable for comparisons + that take commutativity into account. + If we wanted to also support associative rules, we'd have to use a different + strategy to avoid returning spurious 0, e.g. return ~(~0U >> 1) . + We used to have a MODE argument for hashing for CONST_INTs, but that + didn't make sense, since it caused spurious hash differences between + (set (reg:SI 1) (const_int)) + (plus:SI (reg:SI 2) (reg:SI 1)) + and + (plus:SI (reg:SI 2) (const_int)) + If the mode is important in any context, it must be checked specifically + in a comparison anyway, since relying on hash differences is unsafe. */ + +static unsigned int +cselib_hash_rtx (rtx x, int create) +{ + cselib_val *e; + int i, j; + enum rtx_code code; + const char *fmt; + unsigned int hash = 0; + + code = GET_CODE (x); + hash += (unsigned) code + (unsigned) GET_MODE (x); + + switch (code) + { + case MEM: + case REG: + e = cselib_lookup (x, GET_MODE (x), create); + if (! e) + return 0; + + return e->value; + + case CONST_INT: + hash += ((unsigned) CONST_INT << 7) + INTVAL (x); + return hash ? hash : (unsigned int) CONST_INT; + + case CONST_DOUBLE: + /* This is like the general case, except that it only counts + the integers representing the constant. */ + hash += (unsigned) code + (unsigned) GET_MODE (x); + if (GET_MODE (x) != VOIDmode) + hash += real_hash (CONST_DOUBLE_REAL_VALUE (x)); + else + hash += ((unsigned) CONST_DOUBLE_LOW (x) + + (unsigned) CONST_DOUBLE_HIGH (x)); + return hash ? hash : (unsigned int) CONST_DOUBLE; + + case CONST_VECTOR: + { + int units; + rtx elt; + + units = CONST_VECTOR_NUNITS (x); + + for (i = 0; i < units; ++i) + { + elt = CONST_VECTOR_ELT (x, i); + hash += cselib_hash_rtx (elt, 0); + } + + return hash; + } + + /* Assume there is only one rtx object for any given label. */ + case LABEL_REF: + /* We don't hash on the address of the CODE_LABEL to avoid bootstrap + differences and differences between each stage's debugging dumps. */ + hash += (((unsigned int) LABEL_REF << 7) + + CODE_LABEL_NUMBER (XEXP (x, 0))); + return hash ? hash : (unsigned int) LABEL_REF; + + case SYMBOL_REF: + { + /* Don't hash on the symbol's address to avoid bootstrap differences. + Different hash values may cause expressions to be recorded in + different orders and thus different registers to be used in the + final assembler. This also avoids differences in the dump files + between various stages. */ + unsigned int h = 0; + const unsigned char *p = (const unsigned char *) XSTR (x, 0); + + while (*p) + h += (h << 7) + *p++; /* ??? revisit */ + + hash += ((unsigned int) SYMBOL_REF << 7) + h; + return hash ? hash : (unsigned int) SYMBOL_REF; + } + + case PRE_DEC: + case PRE_INC: + case POST_DEC: + case POST_INC: + case POST_MODIFY: + case PRE_MODIFY: + case PC: + case CC0: + case CALL: + case UNSPEC_VOLATILE: + return 0; + + case ASM_OPERANDS: + if (MEM_VOLATILE_P (x)) + return 0; + + break; + + default: + break; + } + + i = GET_RTX_LENGTH (code) - 1; + fmt = GET_RTX_FORMAT (code); + for (; i >= 0; i--) + { + switch (fmt[i]) + { + case 'e': + { + rtx tem = XEXP (x, i); + unsigned int tem_hash = cselib_hash_rtx (tem, create); + + if (tem_hash == 0) + return 0; + + hash += tem_hash; + } + break; + case 'E': + for (j = 0; j < XVECLEN (x, i); j++) + { + unsigned int tem_hash + = cselib_hash_rtx (XVECEXP (x, i, j), create); + + if (tem_hash == 0) + return 0; + + hash += tem_hash; + } + break; + + case 's': + { + const unsigned char *p = (const unsigned char *) XSTR (x, i); + + if (p) + while (*p) + hash += *p++; + break; + } + + case 'i': + hash += XINT (x, i); + break; + + case '0': + case 't': + /* unused */ + break; + + default: + gcc_unreachable (); + } + } + + return hash ? hash : 1 + (unsigned int) GET_CODE (x); +} + +/* Create a new value structure for VALUE and initialize it. The mode of the + value is MODE. */ + +static inline cselib_val * +new_cselib_val (unsigned int value, enum machine_mode mode) +{ + cselib_val *e = pool_alloc (cselib_val_pool); + + gcc_assert (value); + + e->value = value; + /* We use an alloc pool to allocate this RTL construct because it + accounts for about 8% of the overall memory usage. We know + precisely when we can have VALUE RTXen (when cselib is active) + so we don't need to put them in garbage collected memory. + ??? Why should a VALUE be an RTX in the first place? */ + e->u.val_rtx = pool_alloc (value_pool); + memset (e->u.val_rtx, 0, RTX_HDR_SIZE); + PUT_CODE (e->u.val_rtx, VALUE); + PUT_MODE (e->u.val_rtx, mode); + CSELIB_VAL_PTR (e->u.val_rtx) = e; + e->addr_list = 0; + e->locs = 0; + e->next_containing_mem = 0; + return e; +} + +/* ADDR_ELT is a value that is used as address. MEM_ELT is the value that + contains the data at this address. X is a MEM that represents the + value. Update the two value structures to represent this situation. */ + +static void +add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x) +{ + struct elt_loc_list *l; + + /* Avoid duplicates. */ + for (l = mem_elt->locs; l; l = l->next) + if (MEM_P (l->loc) + && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt) + return; + + addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt); + mem_elt->locs + = new_elt_loc_list (mem_elt->locs, + replace_equiv_address_nv (x, addr_elt->u.val_rtx)); + if (mem_elt->next_containing_mem == NULL) + { + mem_elt->next_containing_mem = first_containing_mem; + first_containing_mem = mem_elt; + } +} + +/* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx. + If CREATE, make a new one if we haven't seen it before. */ + +static cselib_val * +cselib_lookup_mem (rtx x, int create) +{ + enum machine_mode mode = GET_MODE (x); + void **slot; + cselib_val *addr; + cselib_val *mem_elt; + struct elt_list *l; + + if (MEM_VOLATILE_P (x) || mode == BLKmode + || !cselib_record_memory + || (FLOAT_MODE_P (mode) && flag_float_store)) + return 0; + + /* Look up the value for the address. */ + addr = cselib_lookup (XEXP (x, 0), mode, create); + if (! addr) + return 0; + + /* Find a value that describes a value of our mode at that address. */ + for (l = addr->addr_list; l; l = l->next) + if (GET_MODE (l->elt->u.val_rtx) == mode) + return l->elt; + + if (! create) + return 0; + + mem_elt = new_cselib_val (++next_unknown_value, mode); + add_mem_for_addr (addr, mem_elt, x); + slot = htab_find_slot_with_hash (cselib_hash_table, wrap_constant (mode, x), + mem_elt->value, INSERT); + *slot = mem_elt; + return mem_elt; +} + +/* Walk rtx X and replace all occurrences of REG and MEM subexpressions + with VALUE expressions. This way, it becomes independent of changes + to registers and memory. + X isn't actually modified; if modifications are needed, new rtl is + allocated. However, the return value can share rtl with X. */ + +rtx +cselib_subst_to_values (rtx x) +{ + enum rtx_code code = GET_CODE (x); + const char *fmt = GET_RTX_FORMAT (code); + cselib_val *e; + struct elt_list *l; + rtx copy = x; + int i; + + switch (code) + { + case REG: + l = REG_VALUES (REGNO (x)); + if (l && l->elt == NULL) + l = l->next; + for (; l; l = l->next) + if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x)) + return l->elt->u.val_rtx; + + gcc_unreachable (); + + case MEM: + e = cselib_lookup_mem (x, 0); + if (! e) + { + /* This happens for autoincrements. Assign a value that doesn't + match any other. */ + e = new_cselib_val (++next_unknown_value, GET_MODE (x)); + } + return e->u.val_rtx; + + case CONST_DOUBLE: + case CONST_VECTOR: + case CONST_INT: + return x; + + case POST_INC: + case PRE_INC: + case POST_DEC: + case PRE_DEC: + case POST_MODIFY: + case PRE_MODIFY: + e = new_cselib_val (++next_unknown_value, GET_MODE (x)); + return e->u.val_rtx; + + default: + break; + } + + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'e') + { + rtx t = cselib_subst_to_values (XEXP (x, i)); + + if (t != XEXP (x, i) && x == copy) + copy = shallow_copy_rtx (x); + + XEXP (copy, i) = t; + } + else if (fmt[i] == 'E') + { + int j, k; + + for (j = 0; j < XVECLEN (x, i); j++) + { + rtx t = cselib_subst_to_values (XVECEXP (x, i, j)); + + if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i)) + { + if (x == copy) + copy = shallow_copy_rtx (x); + + XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i)); + for (k = 0; k < j; k++) + XVECEXP (copy, i, k) = XVECEXP (x, i, k); + } + + XVECEXP (copy, i, j) = t; + } + } + } + + return copy; +} + +/* Look up the rtl expression X in our tables and return the value it has. + If CREATE is zero, we return NULL if we don't know the value. Otherwise, + we create a new one if possible, using mode MODE if X doesn't have a mode + (i.e. because it's a constant). */ + +cselib_val * +cselib_lookup (rtx x, enum machine_mode mode, int create) +{ + void **slot; + cselib_val *e; + unsigned int hashval; + + if (GET_MODE (x) != VOIDmode) + mode = GET_MODE (x); + + if (GET_CODE (x) == VALUE) + return CSELIB_VAL_PTR (x); + + if (REG_P (x)) + { + struct elt_list *l; + unsigned int i = REGNO (x); + + l = REG_VALUES (i); + if (l && l->elt == NULL) + l = l->next; + for (; l; l = l->next) + if (mode == GET_MODE (l->elt->u.val_rtx)) + return l->elt; + + if (! create) + return 0; + + if (i < FIRST_PSEUDO_REGISTER) + { + unsigned int n = hard_regno_nregs[i][mode]; + + if (n > max_value_regs) + max_value_regs = n; + } + + e = new_cselib_val (++next_unknown_value, GET_MODE (x)); + e->locs = new_elt_loc_list (e->locs, x); + if (REG_VALUES (i) == 0) + { + /* Maintain the invariant that the first entry of + REG_VALUES, if present, must be the value used to set the + register, or NULL. */ + used_regs[n_used_regs++] = i; + REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL); + } + REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e); + slot = htab_find_slot_with_hash (cselib_hash_table, x, e->value, INSERT); + *slot = e; + return e; + } + + if (MEM_P (x)) + return cselib_lookup_mem (x, create); + + hashval = cselib_hash_rtx (x, create); + /* Can't even create if hashing is not possible. */ + if (! hashval) + return 0; + + slot = htab_find_slot_with_hash (cselib_hash_table, wrap_constant (mode, x), + hashval, create ? INSERT : NO_INSERT); + if (slot == 0) + return 0; + + e = (cselib_val *) *slot; + if (e) + return e; + + e = new_cselib_val (hashval, mode); + + /* We have to fill the slot before calling cselib_subst_to_values: + the hash table is inconsistent until we do so, and + cselib_subst_to_values will need to do lookups. */ + *slot = (void *) e; + e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x)); + return e; +} + +/* Invalidate any entries in reg_values that overlap REGNO. This is called + if REGNO is changing. MODE is the mode of the assignment to REGNO, which + is used to determine how many hard registers are being changed. If MODE + is VOIDmode, then only REGNO is being changed; this is used when + invalidating call clobbered registers across a call. */ + +static void +cselib_invalidate_regno (unsigned int regno, enum machine_mode mode) +{ + unsigned int endregno; + unsigned int i; + + /* If we see pseudos after reload, something is _wrong_. */ + gcc_assert (!reload_completed || regno < FIRST_PSEUDO_REGISTER + || reg_renumber[regno] < 0); + + /* Determine the range of registers that must be invalidated. For + pseudos, only REGNO is affected. For hard regs, we must take MODE + into account, and we must also invalidate lower register numbers + if they contain values that overlap REGNO. */ + if (regno < FIRST_PSEUDO_REGISTER) + { + gcc_assert (mode != VOIDmode); + + if (regno < max_value_regs) + i = 0; + else + i = regno - max_value_regs; + + endregno = regno + hard_regno_nregs[regno][mode]; + } + else + { + i = regno; + endregno = regno + 1; + } + + for (; i < endregno; i++) + { + struct elt_list **l = ®_VALUES (i); + + /* Go through all known values for this reg; if it overlaps the range + we're invalidating, remove the value. */ + while (*l) + { + cselib_val *v = (*l)->elt; + struct elt_loc_list **p; + unsigned int this_last = i; + + if (i < FIRST_PSEUDO_REGISTER && v != NULL) + this_last += hard_regno_nregs[i][GET_MODE (v->u.val_rtx)] - 1; + + if (this_last < regno || v == NULL) + { + l = &(*l)->next; + continue; + } + + /* We have an overlap. */ + if (*l == REG_VALUES (i)) + { + /* Maintain the invariant that the first entry of + REG_VALUES, if present, must be the value used to set + the register, or NULL. This is also nice because + then we won't push the same regno onto user_regs + multiple times. */ + (*l)->elt = NULL; + l = &(*l)->next; + } + else + unchain_one_elt_list (l); + + /* Now, we clear the mapping from value to reg. It must exist, so + this code will crash intentionally if it doesn't. */ + for (p = &v->locs; ; p = &(*p)->next) + { + rtx x = (*p)->loc; + + if (REG_P (x) && REGNO (x) == i) + { + unchain_one_elt_loc_list (p); + break; + } + } + if (v->locs == 0) + n_useless_values++; + } + } +} + +/* Return 1 if X has a value that can vary even between two + executions of the program. 0 means X can be compared reliably + against certain constants or near-constants. */ + +static int +cselib_rtx_varies_p (rtx x ATTRIBUTE_UNUSED, int from_alias ATTRIBUTE_UNUSED) +{ + /* We actually don't need to verify very hard. This is because + if X has actually changed, we invalidate the memory anyway, + so assume that all common memory addresses are + invariant. */ + return 0; +} + +/* Invalidate any locations in the table which are changed because of a + store to MEM_RTX. If this is called because of a non-const call + instruction, MEM_RTX is (mem:BLK const0_rtx). */ + +static void +cselib_invalidate_mem (rtx mem_rtx) +{ + cselib_val **vp, *v, *next; + int num_mems = 0; + rtx mem_addr; + + mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0))); + mem_rtx = canon_rtx (mem_rtx); + + vp = &first_containing_mem; + for (v = *vp; v != &dummy_val; v = next) + { + bool has_mem = false; + struct elt_loc_list **p = &v->locs; + int had_locs = v->locs != 0; + + while (*p) + { + rtx x = (*p)->loc; + cselib_val *addr; + struct elt_list **mem_chain; + + /* MEMs may occur in locations only at the top level; below + that every MEM or REG is substituted by its VALUE. */ + if (!MEM_P (x)) + { + p = &(*p)->next; + continue; + } + if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS) + && ! canon_true_dependence (mem_rtx, GET_MODE (mem_rtx), mem_addr, + x, cselib_rtx_varies_p)) + { + has_mem = true; + num_mems++; + p = &(*p)->next; + continue; + } + + /* This one overlaps. */ + /* We must have a mapping from this MEM's address to the + value (E). Remove that, too. */ + addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0); + mem_chain = &addr->addr_list; + for (;;) + { + if ((*mem_chain)->elt == v) + { + unchain_one_elt_list (mem_chain); + break; + } + + mem_chain = &(*mem_chain)->next; + } + + unchain_one_elt_loc_list (p); + } + + if (had_locs && v->locs == 0) + n_useless_values++; + + next = v->next_containing_mem; + if (has_mem) + { + *vp = v; + vp = &(*vp)->next_containing_mem; + } + else + v->next_containing_mem = NULL; + } + *vp = &dummy_val; +} + +/* Invalidate DEST, which is being assigned to or clobbered. */ + +void +cselib_invalidate_rtx (rtx dest) +{ + while (GET_CODE (dest) == SUBREG + || GET_CODE (dest) == ZERO_EXTRACT + || GET_CODE (dest) == STRICT_LOW_PART) + dest = XEXP (dest, 0); + + if (REG_P (dest)) + cselib_invalidate_regno (REGNO (dest), GET_MODE (dest)); + else if (MEM_P (dest)) + cselib_invalidate_mem (dest); + + /* Some machines don't define AUTO_INC_DEC, but they still use push + instructions. We need to catch that case here in order to + invalidate the stack pointer correctly. Note that invalidating + the stack pointer is different from invalidating DEST. */ + if (push_operand (dest, GET_MODE (dest))) + cselib_invalidate_rtx (stack_pointer_rtx); +} + +/* A wrapper for cselib_invalidate_rtx to be called via note_stores. */ + +static void +cselib_invalidate_rtx_note_stores (rtx dest, rtx ignore ATTRIBUTE_UNUSED, + void *data ATTRIBUTE_UNUSED) +{ + cselib_invalidate_rtx (dest); +} + +/* Record the result of a SET instruction. DEST is being set; the source + contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT + describes its address. */ + +static void +cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt) +{ + int dreg = REG_P (dest) ? (int) REGNO (dest) : -1; + + if (src_elt == 0 || side_effects_p (dest)) + return; + + if (dreg >= 0) + { + if (dreg < FIRST_PSEUDO_REGISTER) + { + unsigned int n = hard_regno_nregs[dreg][GET_MODE (dest)]; + + if (n > max_value_regs) + max_value_regs = n; + } + + if (REG_VALUES (dreg) == 0) + { + used_regs[n_used_regs++] = dreg; + REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt); + } + else + { + /* The register should have been invalidated. */ + gcc_assert (REG_VALUES (dreg)->elt == 0); + REG_VALUES (dreg)->elt = src_elt; + } + + if (src_elt->locs == 0) + n_useless_values--; + src_elt->locs = new_elt_loc_list (src_elt->locs, dest); + } + else if (MEM_P (dest) && dest_addr_elt != 0 + && cselib_record_memory) + { + if (src_elt->locs == 0) + n_useless_values--; + add_mem_for_addr (dest_addr_elt, src_elt, dest); + } +} + +/* Describe a single set that is part of an insn. */ +struct set +{ + rtx src; + rtx dest; + cselib_val *src_elt; + cselib_val *dest_addr_elt; +}; + +/* There is no good way to determine how many elements there can be + in a PARALLEL. Since it's fairly cheap, use a really large number. */ +#define MAX_SETS (FIRST_PSEUDO_REGISTER * 2) + +/* Record the effects of any sets in INSN. */ +static void +cselib_record_sets (rtx insn) +{ + int n_sets = 0; + int i; + struct set sets[MAX_SETS]; + rtx body = PATTERN (insn); + rtx cond = 0; + + body = PATTERN (insn); + if (GET_CODE (body) == COND_EXEC) + { + cond = COND_EXEC_TEST (body); + body = COND_EXEC_CODE (body); + } + + /* Find all sets. */ + if (GET_CODE (body) == SET) + { + sets[0].src = SET_SRC (body); + sets[0].dest = SET_DEST (body); + n_sets = 1; + } + else if (GET_CODE (body) == PARALLEL) + { + /* Look through the PARALLEL and record the values being + set, if possible. Also handle any CLOBBERs. */ + for (i = XVECLEN (body, 0) - 1; i >= 0; --i) + { + rtx x = XVECEXP (body, 0, i); + + if (GET_CODE (x) == SET) + { + sets[n_sets].src = SET_SRC (x); + sets[n_sets].dest = SET_DEST (x); + n_sets++; + } + } + } + + /* Look up the values that are read. Do this before invalidating the + locations that are written. */ + for (i = 0; i < n_sets; i++) + { + rtx dest = sets[i].dest; + + /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for + the low part after invalidating any knowledge about larger modes. */ + if (GET_CODE (sets[i].dest) == STRICT_LOW_PART) + sets[i].dest = dest = XEXP (dest, 0); + + /* We don't know how to record anything but REG or MEM. */ + if (REG_P (dest) + || (MEM_P (dest) && cselib_record_memory)) + { + rtx src = sets[i].src; + if (cond) + src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest); + sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1); + if (MEM_P (dest)) + sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1); + else + sets[i].dest_addr_elt = 0; + } + } + + /* Invalidate all locations written by this insn. Note that the elts we + looked up in the previous loop aren't affected, just some of their + locations may go away. */ + note_stores (body, cselib_invalidate_rtx_note_stores, NULL); + + /* If this is an asm, look for duplicate sets. This can happen when the + user uses the same value as an output multiple times. This is valid + if the outputs are not actually used thereafter. Treat this case as + if the value isn't actually set. We do this by smashing the destination + to pc_rtx, so that we won't record the value later. */ + if (n_sets >= 2 && asm_noperands (body) >= 0) + { + for (i = 0; i < n_sets; i++) + { + rtx dest = sets[i].dest; + if (REG_P (dest) || MEM_P (dest)) + { + int j; + for (j = i + 1; j < n_sets; j++) + if (rtx_equal_p (dest, sets[j].dest)) + { + sets[i].dest = pc_rtx; + sets[j].dest = pc_rtx; + } + } + } + } + + /* Now enter the equivalences in our tables. */ + for (i = 0; i < n_sets; i++) + { + rtx dest = sets[i].dest; + if (REG_P (dest) + || (MEM_P (dest) && cselib_record_memory)) + cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt); + } +} + +/* Record the effects of INSN. */ + +void +cselib_process_insn (rtx insn) +{ + int i; + rtx x; + + if (find_reg_note (insn, REG_LIBCALL, NULL)) + cselib_current_insn_in_libcall = true; + cselib_current_insn = insn; + + /* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp. */ + if (LABEL_P (insn) + || (CALL_P (insn) + && find_reg_note (insn, REG_SETJMP, NULL)) + || (NONJUMP_INSN_P (insn) + && GET_CODE (PATTERN (insn)) == ASM_OPERANDS + && MEM_VOLATILE_P (PATTERN (insn)))) + { + if (find_reg_note (insn, REG_RETVAL, NULL)) + cselib_current_insn_in_libcall = false; + cselib_clear_table (); + return; + } + + if (! INSN_P (insn)) + { + if (find_reg_note (insn, REG_RETVAL, NULL)) + cselib_current_insn_in_libcall = false; + cselib_current_insn = 0; + return; + } + + /* If this is a call instruction, forget anything stored in a + call clobbered register, or, if this is not a const call, in + memory. */ + if (CALL_P (insn)) + { + for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) + if (call_used_regs[i] + || (REG_VALUES (i) && REG_VALUES (i)->elt + && HARD_REGNO_CALL_PART_CLOBBERED (i, + GET_MODE (REG_VALUES (i)->elt->u.val_rtx)))) + cselib_invalidate_regno (i, reg_raw_mode[i]); + + if (! CONST_OR_PURE_CALL_P (insn)) + cselib_invalidate_mem (callmem); + } + + cselib_record_sets (insn); + +#ifdef AUTO_INC_DEC + /* Clobber any registers which appear in REG_INC notes. We + could keep track of the changes to their values, but it is + unlikely to help. */ + for (x = REG_NOTES (insn); x; x = XEXP (x, 1)) + if (REG_NOTE_KIND (x) == REG_INC) + cselib_invalidate_rtx (XEXP (x, 0)); +#endif + + /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only + after we have processed the insn. */ + if (CALL_P (insn)) + for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1)) + if (GET_CODE (XEXP (x, 0)) == CLOBBER) + cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0)); + + if (find_reg_note (insn, REG_RETVAL, NULL)) + cselib_current_insn_in_libcall = false; + cselib_current_insn = 0; + + if (n_useless_values > MAX_USELESS_VALUES + /* remove_useless_values is linear in the hash table size. Avoid + quadratic behaviour for very large hashtables with very few + useless elements. */ + && (unsigned int)n_useless_values > cselib_hash_table->n_elements / 4) + remove_useless_values (); +} + +/* Initialize cselib for one pass. The caller must also call + init_alias_analysis. */ + +void +cselib_init (bool record_memory) +{ + elt_list_pool = create_alloc_pool ("elt_list", + sizeof (struct elt_list), 10); + elt_loc_list_pool = create_alloc_pool ("elt_loc_list", + sizeof (struct elt_loc_list), 10); + cselib_val_pool = create_alloc_pool ("cselib_val_list", + sizeof (cselib_val), 10); + value_pool = create_alloc_pool ("value", RTX_CODE_SIZE (VALUE), 100); + cselib_record_memory = record_memory; + /* This is only created once. */ + if (! callmem) + callmem = gen_rtx_MEM (BLKmode, const0_rtx); + + cselib_nregs = max_reg_num (); + + /* We preserve reg_values to allow expensive clearing of the whole thing. + Reallocate it however if it happens to be too large. */ + if (!reg_values || reg_values_size < cselib_nregs + || (reg_values_size > 10 && reg_values_size > cselib_nregs * 4)) + { + if (reg_values) + free (reg_values); + /* Some space for newly emit instructions so we don't end up + reallocating in between passes. */ + reg_values_size = cselib_nregs + (63 + cselib_nregs) / 16; + reg_values = XCNEWVEC (struct elt_list *, reg_values_size); + } + used_regs = XNEWVEC (unsigned int, cselib_nregs); + n_used_regs = 0; + cselib_hash_table = htab_create (31, get_value_hash, + entry_and_rtx_equal_p, NULL); + cselib_current_insn_in_libcall = false; +} + +/* Called when the current user is done with cselib. */ + +void +cselib_finish (void) +{ + free_alloc_pool (elt_list_pool); + free_alloc_pool (elt_loc_list_pool); + free_alloc_pool (cselib_val_pool); + free_alloc_pool (value_pool); + cselib_clear_table (); + htab_delete (cselib_hash_table); + free (used_regs); + used_regs = 0; + cselib_hash_table = 0; + n_useless_values = 0; + next_unknown_value = 0; +} + +#include "gt-cselib.h" |
