+++ /dev/null
-/* Global constant/copy propagation for RTL.
- Copyright (C) 1997-2015 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 3, 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 COPYING3. If not see
-<http://www.gnu.org/licenses/>. */
-
-#include "config.h"
-#include "system.h"
-#include "coretypes.h"
-#include "tm.h"
-#include "diagnostic-core.h"
-#include "toplev.h"
-#include "rtl.h"
-#include "hash-set.h"
-#include "machmode.h"
-#include "vec.h"
-#include "double-int.h"
-#include "input.h"
-#include "alias.h"
-#include "symtab.h"
-#include "wide-int.h"
-#include "inchash.h"
-#include "tree.h"
-#include "tm_p.h"
-#include "regs.h"
-#include "hard-reg-set.h"
-#include "flags.h"
-#include "insn-config.h"
-#include "recog.h"
-#include "predict.h"
-#include "hashtab.h"
-#include "function.h"
-#include "dominance.h"
-#include "cfg.h"
-#include "cfgrtl.h"
-#include "cfganal.h"
-#include "lcm.h"
-#include "cfgcleanup.h"
-#include "basic-block.h"
-#include "statistics.h"
-#include "real.h"
-#include "fixed-value.h"
-#include "expmed.h"
-#include "dojump.h"
-#include "explow.h"
-#include "calls.h"
-#include "emit-rtl.h"
-#include "varasm.h"
-#include "stmt.h"
-#include "expr.h"
-#include "except.h"
-#include "params.h"
-#include "cselib.h"
-#include "intl.h"
-#include "obstack.h"
-#include "tree-pass.h"
-#include "df.h"
-#include "dbgcnt.h"
-#include "target.h"
-#include "cfgloop.h"
-
-\f
-/* An obstack for our working variables. */
-static struct obstack cprop_obstack;
-
-/* Occurrence of an expression.
- There is one per basic block. If a pattern appears more than once the
- last appearance is used. */
-
-struct cprop_occr
-{
- /* Next occurrence of this expression. */
- struct cprop_occr *next;
- /* The insn that computes the expression. */
- rtx_insn *insn;
-};
-
-typedef struct cprop_occr *occr_t;
-
-/* Hash table entry for assignment expressions. */
-
-struct cprop_expr
-{
- /* The expression (DEST := SRC). */
- rtx dest;
- rtx src;
-
- /* Index in the available expression bitmaps. */
- int bitmap_index;
- /* Next entry with the same hash. */
- struct cprop_expr *next_same_hash;
- /* List of available occurrence in basic blocks in the function.
- An "available occurrence" is one that is the last occurrence in the
- basic block and whose operands are not modified by following statements
- in the basic block [including this insn]. */
- struct cprop_occr *avail_occr;
-};
-
-/* Hash table for copy propagation expressions.
- Each hash table is an array of buckets.
- ??? It is known that if it were an array of entries, structure elements
- `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
- not clear whether in the final analysis a sufficient amount of memory would
- be saved as the size of the available expression bitmaps would be larger
- [one could build a mapping table without holes afterwards though].
- Someday I'll perform the computation and figure it out. */
-
-struct hash_table_d
-{
- /* The table itself.
- This is an array of `set_hash_table_size' elements. */
- struct cprop_expr **table;
-
- /* Size of the hash table, in elements. */
- unsigned int size;
-
- /* Number of hash table elements. */
- unsigned int n_elems;
-};
-
-/* Copy propagation hash table. */
-static struct hash_table_d set_hash_table;
-
-/* Array of implicit set patterns indexed by basic block index. */
-static rtx *implicit_sets;
-
-/* Array of indexes of expressions for implicit set patterns indexed by basic
- block index. In other words, implicit_set_indexes[i] is the bitmap_index
- of the expression whose RTX is implicit_sets[i]. */
-static int *implicit_set_indexes;
-
-/* Bitmap containing one bit for each register in the program.
- Used when performing GCSE to track which registers have been set since
- the start or end of the basic block while traversing that block. */
-static regset reg_set_bitmap;
-
-/* Various variables for statistics gathering. */
-
-/* Memory used in a pass.
- This isn't intended to be absolutely precise. Its intent is only
- to keep an eye on memory usage. */
-static int bytes_used;
-
-/* Number of local constants propagated. */
-static int local_const_prop_count;
-/* Number of local copies propagated. */
-static int local_copy_prop_count;
-/* Number of global constants propagated. */
-static int global_const_prop_count;
-/* Number of global copies propagated. */
-static int global_copy_prop_count;
-
-#define GOBNEW(T) ((T *) cprop_alloc (sizeof (T)))
-#define GOBNEWVAR(T, S) ((T *) cprop_alloc ((S)))
-
-/* Cover function to obstack_alloc. */
-
-static void *
-cprop_alloc (unsigned long size)
-{
- bytes_used += size;
- return obstack_alloc (&cprop_obstack, size);
-}
-\f
-/* Return nonzero if register X is unchanged from INSN to the end
- of INSN's basic block. */
-
-static int
-reg_available_p (const_rtx x, const rtx_insn *insn ATTRIBUTE_UNUSED)
-{
- return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
-}
-
-/* Hash a set of register REGNO.
-
- Sets are hashed on the register that is set. This simplifies the PRE copy
- propagation code.
-
- ??? May need to make things more elaborate. Later, as necessary. */
-
-static unsigned int
-hash_mod (int regno, int hash_table_size)
-{
- return (unsigned) regno % hash_table_size;
-}
-
-/* Insert assignment DEST:=SET from INSN in the hash table.
- DEST is a register and SET is a register or a suitable constant.
- If the assignment is already present in the table, record it as
- the last occurrence in INSN's basic block.
- IMPLICIT is true if it's an implicit set, false otherwise. */
-
-static void
-insert_set_in_table (rtx dest, rtx src, rtx_insn *insn,
- struct hash_table_d *table, bool implicit)
-{
- bool found = false;
- unsigned int hash;
- struct cprop_expr *cur_expr, *last_expr = NULL;
- struct cprop_occr *cur_occr;
-
- hash = hash_mod (REGNO (dest), table->size);
-
- for (cur_expr = table->table[hash]; cur_expr;
- cur_expr = cur_expr->next_same_hash)
- {
- if (dest == cur_expr->dest
- && src == cur_expr->src)
- {
- found = true;
- break;
- }
- last_expr = cur_expr;
- }
-
- if (! found)
- {
- cur_expr = GOBNEW (struct cprop_expr);
- bytes_used += sizeof (struct cprop_expr);
- if (table->table[hash] == NULL)
- /* This is the first pattern that hashed to this index. */
- table->table[hash] = cur_expr;
- else
- /* Add EXPR to end of this hash chain. */
- last_expr->next_same_hash = cur_expr;
-
- /* Set the fields of the expr element.
- We must copy X because it can be modified when copy propagation is
- performed on its operands. */
- cur_expr->dest = copy_rtx (dest);
- cur_expr->src = copy_rtx (src);
- cur_expr->bitmap_index = table->n_elems++;
- cur_expr->next_same_hash = NULL;
- cur_expr->avail_occr = NULL;
- }
-
- /* Now record the occurrence. */
- cur_occr = cur_expr->avail_occr;
-
- if (cur_occr
- && BLOCK_FOR_INSN (cur_occr->insn) == BLOCK_FOR_INSN (insn))
- {
- /* Found another instance of the expression in the same basic block.
- Prefer this occurrence to the currently recorded one. We want
- the last one in the block and the block is scanned from start
- to end. */
- cur_occr->insn = insn;
- }
- else
- {
- /* First occurrence of this expression in this basic block. */
- cur_occr = GOBNEW (struct cprop_occr);
- bytes_used += sizeof (struct cprop_occr);
- cur_occr->insn = insn;
- cur_occr->next = cur_expr->avail_occr;
- cur_expr->avail_occr = cur_occr;
- }
-
- /* Record bitmap_index of the implicit set in implicit_set_indexes. */
- if (implicit)
- implicit_set_indexes[BLOCK_FOR_INSN (insn)->index]
- = cur_expr->bitmap_index;
-}
-
-/* Determine whether the rtx X should be treated as a constant for CPROP.
- Since X might be inserted more than once we have to take care that it
- is sharable. */
-
-static bool
-cprop_constant_p (const_rtx x)
-{
- return CONSTANT_P (x) && (GET_CODE (x) != CONST || shared_const_p (x));
-}
-
-/* Scan SET present in INSN and add an entry to the hash TABLE.
- IMPLICIT is true if it's an implicit set, false otherwise. */
-
-static void
-hash_scan_set (rtx set, rtx_insn *insn, struct hash_table_d *table,
- bool implicit)
-{
- rtx src = SET_SRC (set);
- rtx dest = SET_DEST (set);
-
- if (REG_P (dest)
- && ! HARD_REGISTER_P (dest)
- && reg_available_p (dest, insn)
- && can_copy_p (GET_MODE (dest)))
- {
- /* See if a REG_EQUAL note shows this equivalent to a simpler expression.
-
- This allows us to do a single CPROP pass and still eliminate
- redundant constants, addresses or other expressions that are
- constructed with multiple instructions.
-
- However, keep the original SRC if INSN is a simple reg-reg move. In
- In this case, there will almost always be a REG_EQUAL note on the
- insn that sets SRC. By recording the REG_EQUAL value here as SRC
- for INSN, we miss copy propagation opportunities.
-
- Note that this does not impede profitable constant propagations. We
- "look through" reg-reg sets in lookup_set. */
- rtx note = find_reg_equal_equiv_note (insn);
- if (note != 0
- && REG_NOTE_KIND (note) == REG_EQUAL
- && !REG_P (src)
- && cprop_constant_p (XEXP (note, 0)))
- src = XEXP (note, 0), set = gen_rtx_SET (VOIDmode, dest, src);
-
- /* Record sets for constant/copy propagation. */
- if ((REG_P (src)
- && src != dest
- && ! HARD_REGISTER_P (src)
- && reg_available_p (src, insn))
- || cprop_constant_p (src))
- insert_set_in_table (dest, src, insn, table, implicit);
- }
-}
-
-/* Process INSN and add hash table entries as appropriate. */
-
-static void
-hash_scan_insn (rtx_insn *insn, struct hash_table_d *table)
-{
- rtx pat = PATTERN (insn);
- int i;
-
- /* Pick out the sets of INSN and for other forms of instructions record
- what's been modified. */
-
- if (GET_CODE (pat) == SET)
- hash_scan_set (pat, insn, table, false);
- else if (GET_CODE (pat) == PARALLEL)
- for (i = 0; i < XVECLEN (pat, 0); i++)
- {
- rtx x = XVECEXP (pat, 0, i);
-
- if (GET_CODE (x) == SET)
- hash_scan_set (x, insn, table, false);
- }
-}
-
-/* Dump the hash table TABLE to file FILE under the name NAME. */
-
-static void
-dump_hash_table (FILE *file, const char *name, struct hash_table_d *table)
-{
- int i;
- /* Flattened out table, so it's printed in proper order. */
- struct cprop_expr **flat_table;
- unsigned int *hash_val;
- struct cprop_expr *expr;
-
- flat_table = XCNEWVEC (struct cprop_expr *, table->n_elems);
- hash_val = XNEWVEC (unsigned int, table->n_elems);
-
- for (i = 0; i < (int) table->size; i++)
- for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
- {
- flat_table[expr->bitmap_index] = expr;
- hash_val[expr->bitmap_index] = i;
- }
-
- fprintf (file, "%s hash table (%d buckets, %d entries)\n",
- name, table->size, table->n_elems);
-
- for (i = 0; i < (int) table->n_elems; i++)
- if (flat_table[i] != 0)
- {
- expr = flat_table[i];
- fprintf (file, "Index %d (hash value %d)\n ",
- expr->bitmap_index, hash_val[i]);
- print_rtl (file, expr->dest);
- fprintf (file, " := ");
- print_rtl (file, expr->src);
- fprintf (file, "\n");
- }
-
- fprintf (file, "\n");
-
- free (flat_table);
- free (hash_val);
-}
-
-/* Record as unavailable all registers that are DEF operands of INSN. */
-
-static void
-make_set_regs_unavailable (rtx_insn *insn)
-{
- df_ref def;
-
- FOR_EACH_INSN_DEF (def, insn)
- SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (def));
-}
-
-/* Top level function to create an assignment hash table.
-
- Assignment entries are placed in the hash table if
- - they are of the form (set (pseudo-reg) src),
- - src is something we want to perform const/copy propagation on,
- - none of the operands or target are subsequently modified in the block
-
- Currently src must be a pseudo-reg or a const_int.
-
- TABLE is the table computed. */
-
-static void
-compute_hash_table_work (struct hash_table_d *table)
-{
- basic_block bb;
-
- /* Allocate vars to track sets of regs. */
- reg_set_bitmap = ALLOC_REG_SET (NULL);
-
- FOR_EACH_BB_FN (bb, cfun)
- {
- rtx_insn *insn;
-
- /* Reset tables used to keep track of what's not yet invalid [since
- the end of the block]. */
- CLEAR_REG_SET (reg_set_bitmap);
-
- /* Go over all insns from the last to the first. This is convenient
- for tracking available registers, i.e. not set between INSN and
- the end of the basic block BB. */
- FOR_BB_INSNS_REVERSE (bb, insn)
- {
- /* Only real insns are interesting. */
- if (!NONDEBUG_INSN_P (insn))
- continue;
-
- /* Record interesting sets from INSN in the hash table. */
- hash_scan_insn (insn, table);
-
- /* Any registers set in INSN will make SETs above it not AVAIL. */
- make_set_regs_unavailable (insn);
- }
-
- /* Insert implicit sets in the hash table, pretending they appear as
- insns at the head of the basic block. */
- if (implicit_sets[bb->index] != NULL_RTX)
- hash_scan_set (implicit_sets[bb->index], BB_HEAD (bb), table, true);
- }
-
- FREE_REG_SET (reg_set_bitmap);
-}
-
-/* Allocate space for the set/expr hash TABLE.
- It is used to determine the number of buckets to use. */
-
-static void
-alloc_hash_table (struct hash_table_d *table)
-{
- int n;
-
- n = get_max_insn_count ();
-
- table->size = n / 4;
- if (table->size < 11)
- table->size = 11;
-
- /* Attempt to maintain efficient use of hash table.
- Making it an odd number is simplest for now.
- ??? Later take some measurements. */
- table->size |= 1;
- n = table->size * sizeof (struct cprop_expr *);
- table->table = XNEWVAR (struct cprop_expr *, n);
-}
-
-/* Free things allocated by alloc_hash_table. */
-
-static void
-free_hash_table (struct hash_table_d *table)
-{
- free (table->table);
-}
-
-/* Compute the hash TABLE for doing copy/const propagation or
- expression hash table. */
-
-static void
-compute_hash_table (struct hash_table_d *table)
-{
- /* Initialize count of number of entries in hash table. */
- table->n_elems = 0;
- memset (table->table, 0, table->size * sizeof (struct cprop_expr *));
-
- compute_hash_table_work (table);
-}
-\f
-/* Expression tracking support. */
-
-/* Lookup REGNO in the set TABLE. The result is a pointer to the
- table entry, or NULL if not found. */
-
-static struct cprop_expr *
-lookup_set (unsigned int regno, struct hash_table_d *table)
-{
- unsigned int hash = hash_mod (regno, table->size);
- struct cprop_expr *expr;
-
- expr = table->table[hash];
-
- while (expr && REGNO (expr->dest) != regno)
- expr = expr->next_same_hash;
-
- return expr;
-}
-
-/* Return the next entry for REGNO in list EXPR. */
-
-static struct cprop_expr *
-next_set (unsigned int regno, struct cprop_expr *expr)
-{
- do
- expr = expr->next_same_hash;
- while (expr && REGNO (expr->dest) != regno);
-
- return expr;
-}
-
-/* Reset tables used to keep track of what's still available [since the
- start of the block]. */
-
-static void
-reset_opr_set_tables (void)
-{
- /* Maintain a bitmap of which regs have been set since beginning of
- the block. */
- CLEAR_REG_SET (reg_set_bitmap);
-}
-
-/* Return nonzero if the register X has not been set yet [since the
- start of the basic block containing INSN]. */
-
-static int
-reg_not_set_p (const_rtx x, const rtx_insn *insn ATTRIBUTE_UNUSED)
-{
- return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
-}
-
-/* Record things set by INSN.
- This data is used by reg_not_set_p. */
-
-static void
-mark_oprs_set (rtx_insn *insn)
-{
- df_ref def;
-
- FOR_EACH_INSN_DEF (def, insn)
- SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (def));
-}
-\f
-/* Compute copy/constant propagation working variables. */
-
-/* Local properties of assignments. */
-static sbitmap *cprop_avloc;
-static sbitmap *cprop_kill;
-
-/* Global properties of assignments (computed from the local properties). */
-static sbitmap *cprop_avin;
-static sbitmap *cprop_avout;
-
-/* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
- basic blocks. N_SETS is the number of sets. */
-
-static void
-alloc_cprop_mem (int n_blocks, int n_sets)
-{
- cprop_avloc = sbitmap_vector_alloc (n_blocks, n_sets);
- cprop_kill = sbitmap_vector_alloc (n_blocks, n_sets);
-
- cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
- cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
-}
-
-/* Free vars used by copy/const propagation. */
-
-static void
-free_cprop_mem (void)
-{
- sbitmap_vector_free (cprop_avloc);
- sbitmap_vector_free (cprop_kill);
- sbitmap_vector_free (cprop_avin);
- sbitmap_vector_free (cprop_avout);
-}
-
-/* Compute the local properties of each recorded expression.
-
- Local properties are those that are defined by the block, irrespective of
- other blocks.
-
- An expression is killed in a block if its operands, either DEST or SRC, are
- modified in the block.
-
- An expression is computed (locally available) in a block if it is computed
- at least once and expression would contain the same value if the
- computation was moved to the end of the block.
-
- KILL and COMP are destination sbitmaps for recording local properties. */
-
-static void
-compute_local_properties (sbitmap *kill, sbitmap *comp,
- struct hash_table_d *table)
-{
- unsigned int i;
-
- /* Initialize the bitmaps that were passed in. */
- bitmap_vector_clear (kill, last_basic_block_for_fn (cfun));
- bitmap_vector_clear (comp, last_basic_block_for_fn (cfun));
-
- for (i = 0; i < table->size; i++)
- {
- struct cprop_expr *expr;
-
- for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
- {
- int indx = expr->bitmap_index;
- df_ref def;
- struct cprop_occr *occr;
-
- /* For each definition of the destination pseudo-reg, the expression
- is killed in the block where the definition is. */
- for (def = DF_REG_DEF_CHAIN (REGNO (expr->dest));
- def; def = DF_REF_NEXT_REG (def))
- bitmap_set_bit (kill[DF_REF_BB (def)->index], indx);
-
- /* If the source is a pseudo-reg, for each definition of the source,
- the expression is killed in the block where the definition is. */
- if (REG_P (expr->src))
- for (def = DF_REG_DEF_CHAIN (REGNO (expr->src));
- def; def = DF_REF_NEXT_REG (def))
- bitmap_set_bit (kill[DF_REF_BB (def)->index], indx);
-
- /* The occurrences recorded in avail_occr are exactly those that
- are locally available in the block where they are. */
- for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
- {
- bitmap_set_bit (comp[BLOCK_FOR_INSN (occr->insn)->index], indx);
- }
- }
- }
-}
-\f
-/* Hash table support. */
-
-/* Top level routine to do the dataflow analysis needed by copy/const
- propagation. */
-
-static void
-compute_cprop_data (void)
-{
- basic_block bb;
-
- compute_local_properties (cprop_kill, cprop_avloc, &set_hash_table);
- compute_available (cprop_avloc, cprop_kill, cprop_avout, cprop_avin);
-
- /* Merge implicit sets into CPROP_AVIN. They are always available at the
- entry of their basic block. We need to do this because 1) implicit sets
- aren't recorded for the local pass so they cannot be propagated within
- their basic block by this pass and 2) the global pass would otherwise
- propagate them only in the successors of their basic block. */
- FOR_EACH_BB_FN (bb, cfun)
- {
- int index = implicit_set_indexes[bb->index];
- if (index != -1)
- bitmap_set_bit (cprop_avin[bb->index], index);
- }
-}
-\f
-/* Copy/constant propagation. */
-
-/* Maximum number of register uses in an insn that we handle. */
-#define MAX_USES 8
-
-/* Table of uses (registers, both hard and pseudo) found in an insn.
- Allocated statically to avoid alloc/free complexity and overhead. */
-static rtx reg_use_table[MAX_USES];
-
-/* Index into `reg_use_table' while building it. */
-static unsigned reg_use_count;
-
-/* Set up a list of register numbers used in INSN. The found uses are stored
- in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
- and contains the number of uses in the table upon exit.
-
- ??? If a register appears multiple times we will record it multiple times.
- This doesn't hurt anything but it will slow things down. */
-
-static void
-find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
-{
- int i, j;
- enum rtx_code code;
- const char *fmt;
- rtx x = *xptr;
-
- /* repeat is used to turn tail-recursion into iteration since GCC
- can't do it when there's no return value. */
- repeat:
- if (x == 0)
- return;
-
- code = GET_CODE (x);
- if (REG_P (x))
- {
- if (reg_use_count == MAX_USES)
- return;
-
- reg_use_table[reg_use_count] = x;
- reg_use_count++;
- }
-
- /* Recursively scan the operands of this expression. */
-
- for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
- {
- if (fmt[i] == 'e')
- {
- /* If we are about to do the last recursive call
- needed at this level, change it into iteration.
- This function is called enough to be worth it. */
- if (i == 0)
- {
- x = XEXP (x, 0);
- goto repeat;
- }
-
- find_used_regs (&XEXP (x, i), data);
- }
- else if (fmt[i] == 'E')
- for (j = 0; j < XVECLEN (x, i); j++)
- find_used_regs (&XVECEXP (x, i, j), data);
- }
-}
-
-/* Try to replace all uses of FROM in INSN with TO.
- Return nonzero if successful. */
-
-static int
-try_replace_reg (rtx from, rtx to, rtx_insn *insn)
-{
- rtx note = find_reg_equal_equiv_note (insn);
- rtx src = 0;
- int success = 0;
- rtx set = single_set (insn);
-
- /* Usually we substitute easy stuff, so we won't copy everything.
- We however need to take care to not duplicate non-trivial CONST
- expressions. */
- to = copy_rtx (to);
-
- validate_replace_src_group (from, to, insn);
- if (num_changes_pending () && apply_change_group ())
- success = 1;
-
- /* Try to simplify SET_SRC if we have substituted a constant. */
- if (success && set && CONSTANT_P (to))
- {
- src = simplify_rtx (SET_SRC (set));
-
- if (src)
- validate_change (insn, &SET_SRC (set), src, 0);
- }
-
- /* If there is already a REG_EQUAL note, update the expression in it
- with our replacement. */
- if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL)
- set_unique_reg_note (insn, REG_EQUAL,
- simplify_replace_rtx (XEXP (note, 0), from, to));
- if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
- {
- /* If above failed and this is a single set, try to simplify the source
- of the set given our substitution. We could perhaps try this for
- multiple SETs, but it probably won't buy us anything. */
- src = simplify_replace_rtx (SET_SRC (set), from, to);
-
- if (!rtx_equal_p (src, SET_SRC (set))
- && validate_change (insn, &SET_SRC (set), src, 0))
- success = 1;
-
- /* If we've failed perform the replacement, have a single SET to
- a REG destination and don't yet have a note, add a REG_EQUAL note
- to not lose information. */
- if (!success && note == 0 && set != 0 && REG_P (SET_DEST (set)))
- note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
- }
-
- if (set && MEM_P (SET_DEST (set)) && reg_mentioned_p (from, SET_DEST (set)))
- {
- /* Registers can also appear as uses in SET_DEST if it is a MEM.
- We could perhaps try this for multiple SETs, but it probably
- won't buy us anything. */
- rtx dest = simplify_replace_rtx (SET_DEST (set), from, to);
-
- if (!rtx_equal_p (dest, SET_DEST (set))
- && validate_change (insn, &SET_DEST (set), dest, 0))
- success = 1;
- }
-
- /* REG_EQUAL may get simplified into register.
- We don't allow that. Remove that note. This code ought
- not to happen, because previous code ought to synthesize
- reg-reg move, but be on the safe side. */
- if (note && REG_NOTE_KIND (note) == REG_EQUAL && REG_P (XEXP (note, 0)))
- remove_note (insn, note);
-
- return success;
-}
-
-/* Find a set of REGNOs that are available on entry to INSN's block. Return
- NULL no such set is found. */
-
-static struct cprop_expr *
-find_avail_set (int regno, rtx_insn *insn)
-{
- /* SET1 contains the last set found that can be returned to the caller for
- use in a substitution. */
- struct cprop_expr *set1 = 0;
-
- /* Loops are not possible here. To get a loop we would need two sets
- available at the start of the block containing INSN. i.e. we would
- need two sets like this available at the start of the block:
-
- (set (reg X) (reg Y))
- (set (reg Y) (reg X))
-
- This can not happen since the set of (reg Y) would have killed the
- set of (reg X) making it unavailable at the start of this block. */
- while (1)
- {
- rtx src;
- struct cprop_expr *set = lookup_set (regno, &set_hash_table);
-
- /* Find a set that is available at the start of the block
- which contains INSN. */
- while (set)
- {
- if (bitmap_bit_p (cprop_avin[BLOCK_FOR_INSN (insn)->index],
- set->bitmap_index))
- break;
- set = next_set (regno, set);
- }
-
- /* If no available set was found we've reached the end of the
- (possibly empty) copy chain. */
- if (set == 0)
- break;
-
- src = set->src;
-
- /* We know the set is available.
- Now check that SRC is locally anticipatable (i.e. none of the
- source operands have changed since the start of the block).
-
- If the source operand changed, we may still use it for the next
- iteration of this loop, but we may not use it for substitutions. */
-
- if (cprop_constant_p (src) || reg_not_set_p (src, insn))
- set1 = set;
-
- /* If the source of the set is anything except a register, then
- we have reached the end of the copy chain. */
- if (! REG_P (src))
- break;
-
- /* Follow the copy chain, i.e. start another iteration of the loop
- and see if we have an available copy into SRC. */
- regno = REGNO (src);
- }
-
- /* SET1 holds the last set that was available and anticipatable at
- INSN. */
- return set1;
-}
-
-/* Subroutine of cprop_insn that tries to propagate constants into
- JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
- it is the instruction that immediately precedes JUMP, and must be a
- single SET of a register. FROM is what we will try to replace,
- SRC is the constant we will try to substitute for it. Return nonzero
- if a change was made. */
-
-static int
-cprop_jump (basic_block bb, rtx_insn *setcc, rtx_insn *jump, rtx from, rtx src)
-{
- rtx new_rtx, set_src, note_src;
- rtx set = pc_set (jump);
- rtx note = find_reg_equal_equiv_note (jump);
-
- if (note)
- {
- note_src = XEXP (note, 0);
- if (GET_CODE (note_src) == EXPR_LIST)
- note_src = NULL_RTX;
- }
- else note_src = NULL_RTX;
-
- /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
- set_src = note_src ? note_src : SET_SRC (set);
-
- /* First substitute the SETCC condition into the JUMP instruction,
- then substitute that given values into this expanded JUMP. */
- if (setcc != NULL_RTX
- && !modified_between_p (from, setcc, jump)
- && !modified_between_p (src, setcc, jump))
- {
- rtx setcc_src;
- rtx setcc_set = single_set (setcc);
- rtx setcc_note = find_reg_equal_equiv_note (setcc);
- setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
- ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
- set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
- setcc_src);
- }
- else
- setcc = NULL;
-
- new_rtx = simplify_replace_rtx (set_src, from, src);
-
- /* If no simplification can be made, then try the next register. */
- if (rtx_equal_p (new_rtx, SET_SRC (set)))
- return 0;
-
- /* If this is now a no-op delete it, otherwise this must be a valid insn. */
- if (new_rtx == pc_rtx)
- delete_insn (jump);
- else
- {
- /* Ensure the value computed inside the jump insn to be equivalent
- to one computed by setcc. */
- if (setcc && modified_in_p (new_rtx, setcc))
- return 0;
- if (! validate_unshare_change (jump, &SET_SRC (set), new_rtx, 0))
- {
- /* When (some) constants are not valid in a comparison, and there
- are two registers to be replaced by constants before the entire
- comparison can be folded into a constant, we need to keep
- intermediate information in REG_EQUAL notes. For targets with
- separate compare insns, such notes are added by try_replace_reg.
- When we have a combined compare-and-branch instruction, however,
- we need to attach a note to the branch itself to make this
- optimization work. */
-
- if (!rtx_equal_p (new_rtx, note_src))
- set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new_rtx));
- return 0;
- }
-
- /* Remove REG_EQUAL note after simplification. */
- if (note_src)
- remove_note (jump, note);
- }
-
-#ifdef HAVE_cc0
- /* Delete the cc0 setter. */
- if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
- delete_insn (setcc);
-#endif
-
- global_const_prop_count++;
- if (dump_file != NULL)
- {
- fprintf (dump_file,
- "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with"
- "constant ", REGNO (from), INSN_UID (jump));
- print_rtl (dump_file, src);
- fprintf (dump_file, "\n");
- }
- purge_dead_edges (bb);
-
- /* If a conditional jump has been changed into unconditional jump, remove
- the jump and make the edge fallthru - this is always called in
- cfglayout mode. */
- if (new_rtx != pc_rtx && simplejump_p (jump))
- {
- edge e;
- edge_iterator ei;
-
- FOR_EACH_EDGE (e, ei, bb->succs)
- if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
- && BB_HEAD (e->dest) == JUMP_LABEL (jump))
- {
- e->flags |= EDGE_FALLTHRU;
- break;
- }
- delete_insn (jump);
- }
-
- return 1;
-}
-
-/* Subroutine of cprop_insn that tries to propagate constants. FROM is what
- we will try to replace, SRC is the constant we will try to substitute for
- it and INSN is the instruction where this will be happening. */
-
-static int
-constprop_register (rtx from, rtx src, rtx_insn *insn)
-{
- rtx sset;
-
- /* Check for reg or cc0 setting instructions followed by
- conditional branch instructions first. */
- if ((sset = single_set (insn)) != NULL
- && NEXT_INSN (insn)
- && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
- {
- rtx dest = SET_DEST (sset);
- if ((REG_P (dest) || CC0_P (dest))
- && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn),
- from, src))
- return 1;
- }
-
- /* Handle normal insns next. */
- if (NONJUMP_INSN_P (insn) && try_replace_reg (from, src, insn))
- return 1;
-
- /* Try to propagate a CONST_INT into a conditional jump.
- We're pretty specific about what we will handle in this
- code, we can extend this as necessary over time.
-
- Right now the insn in question must look like
- (set (pc) (if_then_else ...)) */
- else if (any_condjump_p (insn) && onlyjump_p (insn))
- return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, src);
- return 0;
-}
-
-/* Perform constant and copy propagation on INSN.
- Return nonzero if a change was made. */
-
-static int
-cprop_insn (rtx_insn *insn)
-{
- unsigned i;
- int changed = 0, changed_this_round;
- rtx note;
-
-retry:
- changed_this_round = 0;
- reg_use_count = 0;
- note_uses (&PATTERN (insn), find_used_regs, NULL);
-
- /* We may win even when propagating constants into notes. */
- note = find_reg_equal_equiv_note (insn);
- if (note)
- find_used_regs (&XEXP (note, 0), NULL);
-
- for (i = 0; i < reg_use_count; i++)
- {
- rtx reg_used = reg_use_table[i];
- unsigned int regno = REGNO (reg_used);
- rtx src;
- struct cprop_expr *set;
-
- /* If the register has already been set in this block, there's
- nothing we can do. */
- if (! reg_not_set_p (reg_used, insn))
- continue;
-
- /* Find an assignment that sets reg_used and is available
- at the start of the block. */
- set = find_avail_set (regno, insn);
- if (! set)
- continue;
-
- src = set->src;
-
- /* Constant propagation. */
- if (cprop_constant_p (src))
- {
- if (constprop_register (reg_used, src, insn))
- {
- changed_this_round = changed = 1;
- global_const_prop_count++;
- if (dump_file != NULL)
- {
- fprintf (dump_file,
- "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
- fprintf (dump_file, "insn %d with constant ",
- INSN_UID (insn));
- print_rtl (dump_file, src);
- fprintf (dump_file, "\n");
- }
- if (insn->deleted ())
- return 1;
- }
- }
- else if (REG_P (src)
- && REGNO (src) >= FIRST_PSEUDO_REGISTER
- && REGNO (src) != regno)
- {
- if (try_replace_reg (reg_used, src, insn))
- {
- changed_this_round = changed = 1;
- global_copy_prop_count++;
- if (dump_file != NULL)
- {
- fprintf (dump_file,
- "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
- regno, INSN_UID (insn));
- fprintf (dump_file, " with reg %d\n", REGNO (src));
- }
-
- /* The original insn setting reg_used may or may not now be
- deletable. We leave the deletion to DCE. */
- /* FIXME: If it turns out that the insn isn't deletable,
- then we may have unnecessarily extended register lifetimes
- and made things worse. */
- }
- }
-
- /* If try_replace_reg simplified the insn, the regs found
- by find_used_regs may not be valid anymore. Start over. */
- if (changed_this_round)
- goto retry;
- }
-
- if (changed && DEBUG_INSN_P (insn))
- return 0;
-
- return changed;
-}
-
-/* Like find_used_regs, but avoid recording uses that appear in
- input-output contexts such as zero_extract or pre_dec. This
- restricts the cases we consider to those for which local cprop
- can legitimately make replacements. */
-
-static void
-local_cprop_find_used_regs (rtx *xptr, void *data)
-{
- rtx x = *xptr;
-
- if (x == 0)
- return;
-
- switch (GET_CODE (x))
- {
- case ZERO_EXTRACT:
- case SIGN_EXTRACT:
- case STRICT_LOW_PART:
- return;
-
- case PRE_DEC:
- case PRE_INC:
- case POST_DEC:
- case POST_INC:
- case PRE_MODIFY:
- case POST_MODIFY:
- /* Can only legitimately appear this early in the context of
- stack pushes for function arguments, but handle all of the
- codes nonetheless. */
- return;
-
- case SUBREG:
- /* Setting a subreg of a register larger than word_mode leaves
- the non-written words unchanged. */
- if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
- return;
- break;
-
- default:
- break;
- }
-
- find_used_regs (xptr, data);
-}
-
-/* Try to perform local const/copy propagation on X in INSN. */
-
-static bool
-do_local_cprop (rtx x, rtx_insn *insn)
-{
- rtx newreg = NULL, newcnst = NULL;
-
- /* Rule out USE instructions and ASM statements as we don't want to
- change the hard registers mentioned, and don't change fixed hard
- registers. */
- if (REG_P (x)
- && (REGNO (x) >= FIRST_PSEUDO_REGISTER
- || (GET_CODE (PATTERN (insn)) != USE
- && !fixed_regs[REGNO (x)]
- && asm_noperands (PATTERN (insn)) < 0)))
- {
- cselib_val *val = cselib_lookup (x, GET_MODE (x), 0, VOIDmode);
- struct elt_loc_list *l;
-
- if (!val)
- return false;
- for (l = val->locs; l; l = l->next)
- {
- rtx this_rtx = l->loc;
- rtx note;
-
- if (cprop_constant_p (this_rtx))
- newcnst = this_rtx;
- if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
- /* Don't copy propagate if it has attached REG_EQUIV note.
- At this point this only function parameters should have
- REG_EQUIV notes and if the argument slot is used somewhere
- explicitly, it means address of parameter has been taken,
- so we should not extend the lifetime of the pseudo. */
- && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
- || ! MEM_P (XEXP (note, 0))))
- newreg = this_rtx;
- }
- if (newcnst && constprop_register (x, newcnst, insn))
- {
- if (dump_file != NULL)
- {
- fprintf (dump_file, "LOCAL CONST-PROP: Replacing reg %d in ",
- REGNO (x));
- fprintf (dump_file, "insn %d with constant ",
- INSN_UID (insn));
- print_rtl (dump_file, newcnst);
- fprintf (dump_file, "\n");
- }
- local_const_prop_count++;
- return true;
- }
- else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
- {
- if (dump_file != NULL)
- {
- fprintf (dump_file,
- "LOCAL COPY-PROP: Replacing reg %d in insn %d",
- REGNO (x), INSN_UID (insn));
- fprintf (dump_file, " with reg %d\n", REGNO (newreg));
- }
- local_copy_prop_count++;
- return true;
- }
- }
- return false;
-}
-
-/* Do local const/copy propagation (i.e. within each basic block). */
-
-static int
-local_cprop_pass (void)
-{
- basic_block bb;
- rtx_insn *insn;
- bool changed = false;
- unsigned i;
-
- cselib_init (0);
- FOR_EACH_BB_FN (bb, cfun)
- {
- FOR_BB_INSNS (bb, insn)
- {
- if (INSN_P (insn))
- {
- rtx note = find_reg_equal_equiv_note (insn);
- do
- {
- reg_use_count = 0;
- note_uses (&PATTERN (insn), local_cprop_find_used_regs,
- NULL);
- if (note)
- local_cprop_find_used_regs (&XEXP (note, 0), NULL);
-
- for (i = 0; i < reg_use_count; i++)
- {
- if (do_local_cprop (reg_use_table[i], insn))
- {
- if (!DEBUG_INSN_P (insn))
- changed = true;
- break;
- }
- }
- if (insn->deleted ())
- break;
- }
- while (i < reg_use_count);
- }
- cselib_process_insn (insn);
- }
-
- /* Forget everything at the end of a basic block. */
- cselib_clear_table ();
- }
-
- cselib_finish ();
-
- return changed;
-}
-
-/* Similar to get_condition, only the resulting condition must be
- valid at JUMP, instead of at EARLIEST.
-
- This differs from noce_get_condition in ifcvt.c in that we prefer not to
- settle for the condition variable in the jump instruction being integral.
- We prefer to be able to record the value of a user variable, rather than
- the value of a temporary used in a condition. This could be solved by
- recording the value of *every* register scanned by canonicalize_condition,
- but this would require some code reorganization. */
-
-rtx
-fis_get_condition (rtx_insn *jump)
-{
- return get_condition (jump, NULL, false, true);
-}
-
-/* Check the comparison COND to see if we can safely form an implicit
- set from it. */
-
-static bool
-implicit_set_cond_p (const_rtx cond)
-{
- machine_mode mode;
- rtx cst;
-
- /* COND must be either an EQ or NE comparison. */
- if (GET_CODE (cond) != EQ && GET_CODE (cond) != NE)
- return false;
-
- /* The first operand of COND must be a pseudo-reg. */
- if (! REG_P (XEXP (cond, 0))
- || HARD_REGISTER_P (XEXP (cond, 0)))
- return false;
-
- /* The second operand of COND must be a suitable constant. */
- mode = GET_MODE (XEXP (cond, 0));
- cst = XEXP (cond, 1);
-
- /* We can't perform this optimization if either operand might be or might
- contain a signed zero. */
- if (HONOR_SIGNED_ZEROS (mode))
- {
- /* It is sufficient to check if CST is or contains a zero. We must
- handle float, complex, and vector. If any subpart is a zero, then
- the optimization can't be performed. */
- /* ??? The complex and vector checks are not implemented yet. We just
- always return zero for them. */
- if (CONST_DOUBLE_AS_FLOAT_P (cst))
- {
- REAL_VALUE_TYPE d;
- REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
- if (REAL_VALUES_EQUAL (d, dconst0))
- return 0;
- }
- else
- return 0;
- }
-
- return cprop_constant_p (cst);
-}
-
-/* Find the implicit sets of a function. An "implicit set" is a constraint
- on the value of a variable, implied by a conditional jump. For example,
- following "if (x == 2)", the then branch may be optimized as though the
- conditional performed an "explicit set", in this example, "x = 2". This
- function records the set patterns that are implicit at the start of each
- basic block.
-
- If an implicit set is found but the set is implicit on a critical edge,
- this critical edge is split.
-
- Return true if the CFG was modified, false otherwise. */
-
-static bool
-find_implicit_sets (void)
-{
- basic_block bb, dest;
- rtx cond, new_rtx;
- unsigned int count = 0;
- bool edges_split = false;
- size_t implicit_sets_size = last_basic_block_for_fn (cfun) + 10;
-
- implicit_sets = XCNEWVEC (rtx, implicit_sets_size);
-
- FOR_EACH_BB_FN (bb, cfun)
- {
- /* Check for more than one successor. */
- if (EDGE_COUNT (bb->succs) <= 1)
- continue;
-
- cond = fis_get_condition (BB_END (bb));
-
- /* If no condition is found or if it isn't of a suitable form,
- ignore it. */
- if (! cond || ! implicit_set_cond_p (cond))
- continue;
-
- dest = GET_CODE (cond) == EQ
- ? BRANCH_EDGE (bb)->dest : FALLTHRU_EDGE (bb)->dest;
-
- /* If DEST doesn't go anywhere, ignore it. */
- if (! dest || dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
- continue;
-
- /* We have found a suitable implicit set. Try to record it now as
- a SET in DEST. If DEST has more than one predecessor, the edge
- between BB and DEST is a critical edge and we must split it,
- because we can only record one implicit set per DEST basic block. */
- if (! single_pred_p (dest))
- {
- dest = split_edge (find_edge (bb, dest));
- edges_split = true;
- }
-
- if (implicit_sets_size <= (size_t) dest->index)
- {
- size_t old_implicit_sets_size = implicit_sets_size;
- implicit_sets_size *= 2;
- implicit_sets = XRESIZEVEC (rtx, implicit_sets, implicit_sets_size);
- memset (implicit_sets + old_implicit_sets_size, 0,
- (implicit_sets_size - old_implicit_sets_size) * sizeof (rtx));
- }
-
- new_rtx = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
- XEXP (cond, 1));
- implicit_sets[dest->index] = new_rtx;
- if (dump_file)
- {
- fprintf (dump_file, "Implicit set of reg %d in ",
- REGNO (XEXP (cond, 0)));
- fprintf (dump_file, "basic block %d\n", dest->index);
- }
- count++;
- }
-
- if (dump_file)
- fprintf (dump_file, "Found %d implicit sets\n", count);
-
- /* Confess our sins. */
- return edges_split;
-}
-
-/* Bypass conditional jumps. */
-
-/* The value of last_basic_block at the beginning of the jump_bypass
- pass. The use of redirect_edge_and_branch_force may introduce new
- basic blocks, but the data flow analysis is only valid for basic
- block indices less than bypass_last_basic_block. */
-
-static int bypass_last_basic_block;
-
-/* Find a set of REGNO to a constant that is available at the end of basic
- block BB. Return NULL if no such set is found. Based heavily upon
- find_avail_set. */
-
-static struct cprop_expr *
-find_bypass_set (int regno, int bb)
-{
- struct cprop_expr *result = 0;
-
- for (;;)
- {
- rtx src;
- struct cprop_expr *set = lookup_set (regno, &set_hash_table);
-
- while (set)
- {
- if (bitmap_bit_p (cprop_avout[bb], set->bitmap_index))
- break;
- set = next_set (regno, set);
- }
-
- if (set == 0)
- break;
-
- src = set->src;
- if (cprop_constant_p (src))
- result = set;
-
- if (! REG_P (src))
- break;
-
- regno = REGNO (src);
- }
- return result;
-}
-
-/* Subroutine of bypass_block that checks whether a pseudo is killed by
- any of the instructions inserted on an edge. Jump bypassing places
- condition code setters on CFG edges using insert_insn_on_edge. This
- function is required to check that our data flow analysis is still
- valid prior to commit_edge_insertions. */
-
-static bool
-reg_killed_on_edge (const_rtx reg, const_edge e)
-{
- rtx_insn *insn;
-
- for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
- if (INSN_P (insn) && reg_set_p (reg, insn))
- return true;
-
- return false;
-}
-
-/* Subroutine of bypass_conditional_jumps that attempts to bypass the given
- basic block BB which has more than one predecessor. If not NULL, SETCC
- is the first instruction of BB, which is immediately followed by JUMP_INSN
- JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
- Returns nonzero if a change was made.
-
- During the jump bypassing pass, we may place copies of SETCC instructions
- on CFG edges. The following routine must be careful to pay attention to
- these inserted insns when performing its transformations. */
-
-static int
-bypass_block (basic_block bb, rtx_insn *setcc, rtx_insn *jump)
-{
- rtx_insn *insn;
- rtx note;
- edge e, edest;
- int change;
- int may_be_loop_header = false;
- unsigned removed_p;
- unsigned i;
- edge_iterator ei;
-
- insn = (setcc != NULL) ? setcc : jump;
-
- /* Determine set of register uses in INSN. */
- reg_use_count = 0;
- note_uses (&PATTERN (insn), find_used_regs, NULL);
- note = find_reg_equal_equiv_note (insn);
- if (note)
- find_used_regs (&XEXP (note, 0), NULL);
-
- if (current_loops)
- {
- /* If we are to preserve loop structure then do not bypass
- a loop header. This will either rotate the loop, create
- multiple entry loops or even irreducible regions. */
- if (bb == bb->loop_father->header)
- return 0;
- }
- else
- {
- FOR_EACH_EDGE (e, ei, bb->preds)
- if (e->flags & EDGE_DFS_BACK)
- {
- may_be_loop_header = true;
- break;
- }
- }
-
- change = 0;
- for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
- {
- removed_p = 0;
-
- if (e->flags & EDGE_COMPLEX)
- {
- ei_next (&ei);
- continue;
- }
-
- /* We can't redirect edges from new basic blocks. */
- if (e->src->index >= bypass_last_basic_block)
- {
- ei_next (&ei);
- continue;
- }
-
- /* The irreducible loops created by redirecting of edges entering the
- loop from outside would decrease effectiveness of some of the
- following optimizations, so prevent this. */
- if (may_be_loop_header
- && !(e->flags & EDGE_DFS_BACK))
- {
- ei_next (&ei);
- continue;
- }
-
- for (i = 0; i < reg_use_count; i++)
- {
- rtx reg_used = reg_use_table[i];
- unsigned int regno = REGNO (reg_used);
- basic_block dest, old_dest;
- struct cprop_expr *set;
- rtx src, new_rtx;
-
- set = find_bypass_set (regno, e->src->index);
-
- if (! set)
- continue;
-
- /* Check the data flow is valid after edge insertions. */
- if (e->insns.r && reg_killed_on_edge (reg_used, e))
- continue;
-
- src = SET_SRC (pc_set (jump));
-
- if (setcc != NULL)
- src = simplify_replace_rtx (src,
- SET_DEST (PATTERN (setcc)),
- SET_SRC (PATTERN (setcc)));
-
- new_rtx = simplify_replace_rtx (src, reg_used, set->src);
-
- /* Jump bypassing may have already placed instructions on
- edges of the CFG. We can't bypass an outgoing edge that
- has instructions associated with it, as these insns won't
- get executed if the incoming edge is redirected. */
- if (new_rtx == pc_rtx)
- {
- edest = FALLTHRU_EDGE (bb);
- dest = edest->insns.r ? NULL : edest->dest;
- }
- else if (GET_CODE (new_rtx) == LABEL_REF)
- {
- dest = BLOCK_FOR_INSN (XEXP (new_rtx, 0));
- /* Don't bypass edges containing instructions. */
- edest = find_edge (bb, dest);
- if (edest && edest->insns.r)
- dest = NULL;
- }
- else
- dest = NULL;
-
- /* Avoid unification of the edge with other edges from original
- branch. We would end up emitting the instruction on "both"
- edges. */
- if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc)))
- && find_edge (e->src, dest))
- dest = NULL;
-
- old_dest = e->dest;
- if (dest != NULL
- && dest != old_dest
- && dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
- {
- redirect_edge_and_branch_force (e, dest);
-
- /* Copy the register setter to the redirected edge.
- Don't copy CC0 setters, as CC0 is dead after jump. */
- if (setcc)
- {
- rtx pat = PATTERN (setcc);
- if (!CC0_P (SET_DEST (pat)))
- insert_insn_on_edge (copy_insn (pat), e);
- }
-
- if (dump_file != NULL)
- {
- fprintf (dump_file, "JUMP-BYPASS: Proved reg %d "
- "in jump_insn %d equals constant ",
- regno, INSN_UID (jump));
- print_rtl (dump_file, set->src);
- fprintf (dump_file, "\n\t when BB %d is entered from "
- "BB %d. Redirect edge %d->%d to %d.\n",
- old_dest->index, e->src->index, e->src->index,
- old_dest->index, dest->index);
- }
- change = 1;
- removed_p = 1;
- break;
- }
- }
- if (!removed_p)
- ei_next (&ei);
- }
- return change;
-}
-
-/* Find basic blocks with more than one predecessor that only contain a
- single conditional jump. If the result of the comparison is known at
- compile-time from any incoming edge, redirect that edge to the
- appropriate target. Return nonzero if a change was made.
-
- This function is now mis-named, because we also handle indirect jumps. */
-
-static int
-bypass_conditional_jumps (void)
-{
- basic_block bb;
- int changed;
- rtx_insn *setcc;
- rtx_insn *insn;
- rtx dest;
-
- /* Note we start at block 1. */
- if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
- return 0;
-
- bypass_last_basic_block = last_basic_block_for_fn (cfun);
- mark_dfs_back_edges ();
-
- changed = 0;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb,
- EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
- {
- /* Check for more than one predecessor. */
- if (!single_pred_p (bb))
- {
- setcc = NULL;
- FOR_BB_INSNS (bb, insn)
- if (DEBUG_INSN_P (insn))
- continue;
- else if (NONJUMP_INSN_P (insn))
- {
- if (setcc)
- break;
- if (GET_CODE (PATTERN (insn)) != SET)
- break;
-
- dest = SET_DEST (PATTERN (insn));
- if (REG_P (dest) || CC0_P (dest))
- setcc = insn;
- else
- break;
- }
- else if (JUMP_P (insn))
- {
- if ((any_condjump_p (insn) || computed_jump_p (insn))
- && onlyjump_p (insn))
- changed |= bypass_block (bb, setcc, insn);
- break;
- }
- else if (INSN_P (insn))
- break;
- }
- }
-
- /* If we bypassed any register setting insns, we inserted a
- copy on the redirected edge. These need to be committed. */
- if (changed)
- commit_edge_insertions ();
-
- return changed;
-}
-\f
-/* Return true if the graph is too expensive to optimize. PASS is the
- optimization about to be performed. */
-
-static bool
-is_too_expensive (const char *pass)
-{
- /* Trying to perform global optimizations on flow graphs which have
- a high connectivity will take a long time and is unlikely to be
- particularly useful.
-
- In normal circumstances a cfg should have about twice as many
- edges as blocks. But we do not want to punish small functions
- which have a couple switch statements. Rather than simply
- threshold the number of blocks, uses something with a more
- graceful degradation. */
- if (n_edges_for_fn (cfun) > 20000 + n_basic_blocks_for_fn (cfun) * 4)
- {
- warning (OPT_Wdisabled_optimization,
- "%s: %d basic blocks and %d edges/basic block",
- pass, n_basic_blocks_for_fn (cfun),
- n_edges_for_fn (cfun) / n_basic_blocks_for_fn (cfun));
-
- return true;
- }
-
- /* If allocating memory for the cprop bitmap would take up too much
- storage it's better just to disable the optimization. */
- if ((n_basic_blocks_for_fn (cfun)
- * SBITMAP_SET_SIZE (max_reg_num ())
- * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
- {
- warning (OPT_Wdisabled_optimization,
- "%s: %d basic blocks and %d registers",
- pass, n_basic_blocks_for_fn (cfun), max_reg_num ());
-
- return true;
- }
-
- return false;
-}
-\f
-/* Main function for the CPROP pass. */
-
-static int
-one_cprop_pass (void)
-{
- int i;
- int changed = 0;
-
- /* Return if there's nothing to do, or it is too expensive. */
- if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1
- || is_too_expensive (_ ("const/copy propagation disabled")))
- return 0;
-
- global_const_prop_count = local_const_prop_count = 0;
- global_copy_prop_count = local_copy_prop_count = 0;
-
- bytes_used = 0;
- gcc_obstack_init (&cprop_obstack);
-
- /* Do a local const/copy propagation pass first. The global pass
- only handles global opportunities.
- If the local pass changes something, remove any unreachable blocks
- because the CPROP global dataflow analysis may get into infinite
- loops for CFGs with unreachable blocks.
-
- FIXME: This local pass should not be necessary after CSE (but for
- some reason it still is). It is also (proven) not necessary
- to run the local pass right after FWPWOP.
-
- FIXME: The global analysis would not get into infinite loops if it
- would use the DF solver (via df_simple_dataflow) instead of
- the solver implemented in this file. */
- changed |= local_cprop_pass ();
- if (changed)
- delete_unreachable_blocks ();
-
- /* Determine implicit sets. This may change the CFG (split critical
- edges if that exposes an implicit set).
- Note that find_implicit_sets() does not rely on up-to-date DF caches
- so that we do not have to re-run df_analyze() even if local CPROP
- changed something.
- ??? This could run earlier so that any uncovered implicit sets
- sets could be exploited in local_cprop_pass() also. Later. */
- changed |= find_implicit_sets ();
-
- /* If local_cprop_pass() or find_implicit_sets() changed something,
- run df_analyze() to bring all insn caches up-to-date, and to take
- new basic blocks from edge splitting on the DF radar.
- NB: This also runs the fast DCE pass, because execute_rtl_cprop
- sets DF_LR_RUN_DCE. */
- if (changed)
- df_analyze ();
-
- /* Initialize implicit_set_indexes array. */
- implicit_set_indexes = XNEWVEC (int, last_basic_block_for_fn (cfun));
- for (i = 0; i < last_basic_block_for_fn (cfun); i++)
- implicit_set_indexes[i] = -1;
-
- alloc_hash_table (&set_hash_table);
- compute_hash_table (&set_hash_table);
-
- /* Free implicit_sets before peak usage. */
- free (implicit_sets);
- implicit_sets = NULL;
-
- if (dump_file)
- dump_hash_table (dump_file, "SET", &set_hash_table);
- if (set_hash_table.n_elems > 0)
- {
- basic_block bb;
- rtx_insn *insn;
-
- alloc_cprop_mem (last_basic_block_for_fn (cfun),
- set_hash_table.n_elems);
- compute_cprop_data ();
-
- free (implicit_set_indexes);
- implicit_set_indexes = NULL;
-
- /* Allocate vars to track sets of regs. */
- reg_set_bitmap = ALLOC_REG_SET (NULL);
-
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb,
- EXIT_BLOCK_PTR_FOR_FN (cfun),
- next_bb)
- {
- /* Reset tables used to keep track of what's still valid [since
- the start of the block]. */
- reset_opr_set_tables ();
-
- FOR_BB_INSNS (bb, insn)
- if (INSN_P (insn))
- {
- changed |= cprop_insn (insn);
-
- /* Keep track of everything modified by this insn. */
- /* ??? Need to be careful w.r.t. mods done to INSN.
- Don't call mark_oprs_set if we turned the
- insn into a NOTE, or deleted the insn. */
- if (! NOTE_P (insn) && ! insn->deleted ())
- mark_oprs_set (insn);
- }
- }
-
- changed |= bypass_conditional_jumps ();
-
- FREE_REG_SET (reg_set_bitmap);
- free_cprop_mem ();
- }
- else
- {
- free (implicit_set_indexes);
- implicit_set_indexes = NULL;
- }
-
- free_hash_table (&set_hash_table);
- obstack_free (&cprop_obstack, NULL);
-
- if (dump_file)
- {
- fprintf (dump_file, "CPROP of %s, %d basic blocks, %d bytes needed, ",
- current_function_name (), n_basic_blocks_for_fn (cfun),
- bytes_used);
- fprintf (dump_file, "%d local const props, %d local copy props, ",
- local_const_prop_count, local_copy_prop_count);
- fprintf (dump_file, "%d global const props, %d global copy props\n\n",
- global_const_prop_count, global_copy_prop_count);
- }
-
- return changed;
-}
-\f
-/* All the passes implemented in this file. Each pass has its
- own gate and execute function, and at the end of the file a
- pass definition for passes.c.
-
- We do not construct an accurate cfg in functions which call
- setjmp, so none of these passes runs if the function calls
- setjmp.
- FIXME: Should just handle setjmp via REG_SETJMP notes. */
-
-static unsigned int
-execute_rtl_cprop (void)
-{
- int changed;
- delete_unreachable_blocks ();
- df_set_flags (DF_LR_RUN_DCE);
- df_analyze ();
- changed = one_cprop_pass ();
- flag_rerun_cse_after_global_opts |= changed;
- if (changed)
- cleanup_cfg (CLEANUP_CFG_CHANGED);
- return 0;
-}
-
-namespace {
-
-const pass_data pass_data_rtl_cprop =
-{
- RTL_PASS, /* type */
- "cprop", /* name */
- OPTGROUP_NONE, /* optinfo_flags */
- TV_CPROP, /* tv_id */
- PROP_cfglayout, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_df_finish, /* todo_flags_finish */
-};
-
-class pass_rtl_cprop : public rtl_opt_pass
-{
-public:
- pass_rtl_cprop (gcc::context *ctxt)
- : rtl_opt_pass (pass_data_rtl_cprop, ctxt)
- {}
-
- /* opt_pass methods: */
- opt_pass * clone () { return new pass_rtl_cprop (m_ctxt); }
- virtual bool gate (function *fun)
- {
- return optimize > 0 && flag_gcse
- && !fun->calls_setjmp
- && dbg_cnt (cprop);
- }
-
- virtual unsigned int execute (function *) { return execute_rtl_cprop (); }
-
-}; // class pass_rtl_cprop
-
-} // anon namespace
-
-rtl_opt_pass *
-make_pass_rtl_cprop (gcc::context *ctxt)
-{
- return new pass_rtl_cprop (ctxt);
-}
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