X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=blobdiff_plain;f=gcc%2Ftree-ssa-dse.c;h=9559b4cb2f580d3cc0b47d1d9f70bce652173b9d;hp=596d4a8ee6bc819bca218891dcb69dbeef4e6ee7;hb=49fce50b2ea8ff83917581815b997870ee2cb706;hpb=2bf1fefdcae5d80c19c254454dafca4c44293b3c
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 596d4a8ee6b..9559b4cb2f5 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -1,11 +1,12 @@
/* Dead store elimination
- Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
+ 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)
+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,
@@ -14,9 +15,8 @@ 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. */
+along with GCC; see the file COPYING3. If not see
+. */
#include "config.h"
#include "system.h"
@@ -34,8 +34,7 @@ Boston, MA 02110-1301, USA. */
#include "tree-dump.h"
#include "domwalk.h"
#include "flags.h"
-#include "hashtab.h"
-#include "sbitmap.h"
+#include "langhooks.h"
/* This file implements dead store elimination.
@@ -65,27 +64,7 @@ Boston, MA 02110-1301, USA. */
relationship between dead store and redundant load elimination. In
fact, they are the same transformation applied to different views of
the CFG. */
-
-/* Given an aggregate, this records the parts of it which have been
- stored into. */
-struct aggregate_vardecl_d
-{
- /* The aggregate. */
- tree decl;
-
- /* Some aggregates are too big for us to handle or never get stored
- to as a whole. If this field is TRUE, we don't care about this
- aggregate. */
- bool ignore;
-
- /* Number of parts in the whole. */
- unsigned nparts;
-
- /* A bitmap of parts of the aggregate that have been set. If part N
- of an aggregate has been stored to, bit N should be on. */
- sbitmap parts_set;
-};
struct dse_global_data
{
@@ -95,10 +74,6 @@ struct dse_global_data
that we want to record, set the bit corresponding to the statement's
unique ID in this bitmap. */
bitmap stores;
-
- /* A hash table containing the parts of an aggregate which have been
- stored to. */
- htab_t aggregate_vardecl;
};
/* We allocate a bitmap-per-block for stores which are encountered
@@ -109,39 +84,25 @@ struct dse_block_local_data
bitmap stores;
};
-/* Basic blocks of the potentially dead store and the following
- store, for memory_address_same. */
-struct address_walk_data
-{
- basic_block store1_bb, store2_bb;
-};
-
static bool gate_dse (void);
static unsigned int tree_ssa_dse (void);
static void dse_initialize_block_local_data (struct dom_walk_data *,
basic_block,
bool);
-static void dse_optimize_stmt (struct dom_walk_data *,
- basic_block,
- block_stmt_iterator);
-static void dse_record_phis (struct dom_walk_data *, basic_block);
-static void dse_finalize_block (struct dom_walk_data *, basic_block);
+static void dse_enter_block (struct dom_walk_data *, basic_block);
+static void dse_leave_block (struct dom_walk_data *, basic_block);
static void record_voperand_set (bitmap, bitmap *, unsigned int);
-static void dse_record_partial_aggregate_store (tree, struct dse_global_data *);
-
-static unsigned max_stmt_uid; /* Maximal uid of a statement. Uids to phi
- nodes are assigned using the versions of
- ssa names they define. */
/* Returns uid of statement STMT. */
static unsigned
-get_stmt_uid (tree stmt)
+get_stmt_uid (gimple stmt)
{
- if (TREE_CODE (stmt) == PHI_NODE)
- return SSA_NAME_VERSION (PHI_RESULT (stmt)) + max_stmt_uid;
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ return SSA_NAME_VERSION (gimple_phi_result (stmt))
+ + gimple_stmt_max_uid (cfun);
- return stmt_ann (stmt)->uid;
+ return gimple_uid (stmt);
}
/* Set bit UID in bitmaps GLOBAL and *LOCAL, creating *LOCAL as needed. */
@@ -168,7 +129,8 @@ dse_initialize_block_local_data (struct dom_walk_data *walk_data,
bool recycled)
{
struct dse_block_local_data *bd
- = VEC_last (void_p, walk_data->block_data_stack);
+ = (struct dse_block_local_data *)
+ VEC_last (void_p, walk_data->block_data_stack);
/* If we are given a recycled block local data structure, ensure any
bitmap associated with the block is cleared. */
@@ -179,422 +141,114 @@ dse_initialize_block_local_data (struct dom_walk_data *walk_data,
}
}
-/* Helper function for memory_address_same via walk_tree. Returns
- non-NULL if it finds an SSA_NAME which is part of the address,
- such that the definition of the SSA_NAME post-dominates the store
- we want to delete but not the store that we believe makes it
- redundant. This indicates that the address may change between
- the two stores. */
-
-static tree
-memory_ssa_name_same (tree *expr_p, int *walk_subtrees ATTRIBUTE_UNUSED,
- void *data)
-{
- struct address_walk_data *walk_data = data;
- tree expr = *expr_p;
- tree def_stmt;
- basic_block def_bb;
-
- if (TREE_CODE (expr) != SSA_NAME)
- return NULL_TREE;
-
- /* If we've found a default definition, then there's no problem. Both
- stores will post-dominate it. And def_bb will be NULL. */
- if (SSA_NAME_IS_DEFAULT_DEF (expr))
- return NULL_TREE;
-
- def_stmt = SSA_NAME_DEF_STMT (expr);
- def_bb = bb_for_stmt (def_stmt);
-
- /* DEF_STMT must dominate both stores. So if it is in the same
- basic block as one, it does not post-dominate that store. */
- if (walk_data->store1_bb != def_bb
- && dominated_by_p (CDI_POST_DOMINATORS, walk_data->store1_bb, def_bb))
- {
- if (walk_data->store2_bb == def_bb
- || !dominated_by_p (CDI_POST_DOMINATORS, walk_data->store2_bb,
- def_bb))
- /* Return non-NULL to stop the walk. */
- return def_stmt;
- }
-
- return NULL_TREE;
-}
-
-/* Return TRUE if the destination memory address in STORE1 and STORE2
- might be modified after STORE1, before control reaches STORE2. */
-
-static bool
-memory_address_same (tree store1, tree store2)
-{
- struct address_walk_data walk_data;
-
- walk_data.store1_bb = bb_for_stmt (store1);
- walk_data.store2_bb = bb_for_stmt (store2);
-
- return (walk_tree (&GIMPLE_STMT_OPERAND (store1, 0), memory_ssa_name_same,
- &walk_data, NULL)
- == NULL);
-}
-
-/* Return the use stmt for the lhs of STMT following the virtual
- def-use chains. Returns the MODIFY_EXPR stmt which lhs is equal to
- the lhs of STMT or NULL_TREE if no such stmt can be found. */
-static tree
-get_use_of_stmt_lhs (tree stmt,
- use_operand_p * first_use_p,
- use_operand_p * use_p, tree * use_stmt)
-{
- tree usevar, lhs;
- def_operand_p def_p;
-
- if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
- return NULL_TREE;
-
- lhs = GIMPLE_STMT_OPERAND (stmt, 0);
-
- /* The stmt must have a single VDEF. */
- def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_VDEF);
- if (def_p == NULL_DEF_OPERAND_P)
- return NULL_TREE;
-
- if (!has_single_use (DEF_FROM_PTR (def_p)))
- return NULL_TREE;
- /* Get the immediate use of the def. */
- single_imm_use (DEF_FROM_PTR (def_p), use_p, use_stmt);
- gcc_assert (*use_p != NULL_USE_OPERAND_P);
- first_use_p = use_p;
- if (TREE_CODE (*use_stmt) != GIMPLE_MODIFY_STMT)
- return NULL_TREE;
-
- do
- {
- /* Look at the use stmt and see if it's LHS matches
- stmt's lhs SSA_NAME. */
- def_p = SINGLE_SSA_DEF_OPERAND (*use_stmt, SSA_OP_VDEF);
- if (def_p == NULL_DEF_OPERAND_P)
- return NULL_TREE;
-
- usevar = GIMPLE_STMT_OPERAND (*use_stmt, 0);
- if (operand_equal_p (usevar, lhs, 0))
- return *use_stmt;
-
- if (!has_single_use (DEF_FROM_PTR (def_p)))
- return NULL_TREE;
- single_imm_use (DEF_FROM_PTR (def_p), use_p, use_stmt);
- gcc_assert (*use_p != NULL_USE_OPERAND_P);
- if (TREE_CODE (*use_stmt) != GIMPLE_MODIFY_STMT)
- return NULL_TREE;
- }
- while (1);
-
- return NULL_TREE;
-}
-
/* A helper of dse_optimize_stmt.
- Given a GIMPLE_MODIFY_STMT in STMT, check that each VDEF has one
- use, and that one use is another VDEF clobbering the first one.
-
+ Given a GIMPLE_ASSIGN in STMT, find a candidate statement *USE_STMT that
+ may prove STMT to be dead.
Return TRUE if the above conditions are met, otherwise FALSE. */
static bool
-dse_possible_dead_store_p (tree stmt,
- use_operand_p *first_use_p,
- use_operand_p *use_p,
- tree *use_stmt,
- struct dse_global_data *dse_gd,
- struct dse_block_local_data *bd)
+dse_possible_dead_store_p (gimple stmt, gimple *use_stmt)
{
- ssa_op_iter op_iter;
- bool fail = false;
- def_operand_p var1;
- vuse_vec_p vv;
- tree defvar = NULL_TREE, temp;
- tree prev_defvar = NULL_TREE;
- stmt_ann_t ann = stmt_ann (stmt);
-
- /* We want to verify that each virtual definition in STMT has
- precisely one use and that all the virtual definitions are
- used by the same single statement. When complete, we
- want USE_STMT to refer to the one statement which uses
- all of the virtual definitions from STMT. */
- *use_stmt = NULL;
- FOR_EACH_SSA_VDEF_OPERAND (var1, vv, stmt, op_iter)
- {
- defvar = DEF_FROM_PTR (var1);
-
- /* If this virtual def does not have precisely one use, then
- we will not be able to eliminate STMT. */
- if (!has_single_use (defvar))
- {
- fail = true;
- break;
- }
+ gimple temp;
+ unsigned cnt = 0;
- /* Get the one and only immediate use of DEFVAR. */
- single_imm_use (defvar, use_p, &temp);
- gcc_assert (*use_p != NULL_USE_OPERAND_P);
- *first_use_p = *use_p;
-
- /* In the case of memory partitions, we may get:
+ *use_stmt = NULL;
- # MPT.764_162 = VDEF
- x = {};
- # MPT.764_167 = VDEF
- y = {};
+ /* Find the first dominated statement that clobbers (part of) the
+ memory stmt stores to with no intermediate statement that may use
+ part of the memory stmt stores. That is, find a store that may
+ prove stmt to be a dead store. */
+ temp = stmt;
+ do
+ {
+ gimple prev, use_stmt;
+ imm_use_iterator ui;
+ bool fail = false;
+ tree defvar;
+
+ /* Limit stmt walking to be linear in the number of possibly
+ dead stores. */
+ if (++cnt > 256)
+ return false;
- So we must make sure we're talking about the same LHS.
- */
- if (TREE_CODE (temp) == GIMPLE_MODIFY_STMT)
+ if (gimple_code (temp) == GIMPLE_PHI)
+ defvar = PHI_RESULT (temp);
+ else
+ defvar = gimple_vdef (temp);
+ prev = temp;
+ temp = NULL;
+ FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar)
{
- tree base1 = get_base_address (GIMPLE_STMT_OPERAND (stmt, 0));
- tree base2 = get_base_address (GIMPLE_STMT_OPERAND (temp, 0));
-
- while (base1 && INDIRECT_REF_P (base1))
- base1 = TREE_OPERAND (base1, 0);
- while (base2 && INDIRECT_REF_P (base2))
- base2 = TREE_OPERAND (base2, 0);
+ cnt++;
- if (base1 != base2)
+ /* In simple cases we can look through PHI nodes, but we
+ have to be careful with loops and with memory references
+ containing operands that are also operands of PHI nodes.
+ See gcc.c-torture/execute/20051110-*.c. */
+ if (gimple_code (use_stmt) == GIMPLE_PHI)
{
- fail = true;
- break;
+ if (temp
+ /* We can look through PHIs to post-dominated regions
+ without worrying if the use not also dominates prev
+ (in which case it would be a loop PHI with the use
+ in a latch block). */
+ || gimple_bb (prev) == gimple_bb (use_stmt)
+ || !dominated_by_p (CDI_POST_DOMINATORS,
+ gimple_bb (prev), gimple_bb (use_stmt))
+ || dominated_by_p (CDI_DOMINATORS,
+ gimple_bb (prev), gimple_bb (use_stmt)))
+ {
+ fail = true;
+ BREAK_FROM_IMM_USE_STMT (ui);
+ }
+ temp = use_stmt;
}
- }
-
- /* If the immediate use of DEF_VAR is not the same as the
- previously find immediate uses, then we will not be able
- to eliminate STMT. */
- if (*use_stmt == NULL)
- {
- *use_stmt = temp;
- prev_defvar = defvar;
- }
- else if (temp != *use_stmt)
- {
- /* The immediate use and the previously found immediate use
- must be the same, except... if they're uses of different
- parts of the whole. */
- if (TREE_CODE (defvar) == SSA_NAME
- && TREE_CODE (SSA_NAME_VAR (defvar)) == STRUCT_FIELD_TAG
- && TREE_CODE (prev_defvar) == SSA_NAME
- && TREE_CODE (SSA_NAME_VAR (prev_defvar)) == STRUCT_FIELD_TAG
- && (SFT_PARENT_VAR (SSA_NAME_VAR (defvar))
- == SFT_PARENT_VAR (SSA_NAME_VAR (prev_defvar))))
- ;
- else
+ /* If the statement is a use the store is not dead. */
+ else if (ref_maybe_used_by_stmt_p (use_stmt,
+ gimple_assign_lhs (stmt)))
{
fail = true;
- break;
+ BREAK_FROM_IMM_USE_STMT (ui);
+ }
+ /* If this is a store, remember it or bail out if we have
+ multiple ones (the will be in different CFG parts then). */
+ else if (gimple_vdef (use_stmt))
+ {
+ if (temp)
+ {
+ fail = true;
+ BREAK_FROM_IMM_USE_STMT (ui);
+ }
+ temp = use_stmt;
}
}
- }
- if (fail)
- {
- record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
- dse_record_partial_aggregate_store (stmt, dse_gd);
- return false;
- }
-
- /* Skip through any PHI nodes we have already seen if the PHI
- represents the only use of this store.
-
- Note this does not handle the case where the store has
- multiple VDEFs which all reach a set of PHI nodes in the same block. */
- while (*use_p != NULL_USE_OPERAND_P
- && TREE_CODE (*use_stmt) == PHI_NODE
- && bitmap_bit_p (dse_gd->stores, get_stmt_uid (*use_stmt)))
- {
- /* A PHI node can both define and use the same SSA_NAME if
- the PHI is at the top of a loop and the PHI_RESULT is
- a loop invariant and copies have not been fully propagated.
-
- The safe thing to do is exit assuming no optimization is
- possible. */
- if (SSA_NAME_DEF_STMT (PHI_RESULT (*use_stmt)) == *use_stmt)
+ if (fail)
return false;
- /* Skip past this PHI and loop again in case we had a PHI
- chain. */
- single_imm_use (PHI_RESULT (*use_stmt), use_p, use_stmt);
- }
-
- return true;
-}
-
-
-/* Given a DECL, return its AGGREGATE_VARDECL_D entry. If no entry is
- found and INSERT is TRUE, add a new entry. */
-
-static struct aggregate_vardecl_d *
-get_aggregate_vardecl (tree decl, struct dse_global_data *dse_gd, bool insert)
-{
- struct aggregate_vardecl_d av, *av_p;
- void **slot;
-
- av.decl = decl;
- slot = htab_find_slot (dse_gd->aggregate_vardecl, &av, insert ? INSERT : NO_INSERT);
-
-
- /* Not found, and we don't want to insert. */
- if (slot == NULL)
- return NULL;
-
- /* Create new entry. */
- if (*slot == NULL)
- {
- av_p = XNEW (struct aggregate_vardecl_d);
- av_p->decl = decl;
-
- /* Record how many parts the whole has. */
- if (TREE_CODE (TREE_TYPE (decl)) == COMPLEX_TYPE)
- av_p->nparts = 2;
- else if (TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE)
+ /* If we didn't find any definition this means the store is dead
+ if it isn't a store to global reachable memory. In this case
+ just pretend the stmt makes itself dead. Otherwise fail. */
+ if (!temp)
{
- tree fields;
+ if (is_hidden_global_store (stmt))
+ return false;
- /* Count the number of fields. */
- fields = TYPE_FIELDS (TREE_TYPE (decl));
- av_p->nparts = 0;
- while (fields)
- {
- av_p->nparts++;
- fields = TREE_CHAIN (fields);
- }
+ temp = stmt;
+ break;
}
- else
- abort ();
-
- av_p->ignore = true;
- av_p->parts_set = sbitmap_alloc (HOST_BITS_PER_LONG);
- sbitmap_zero (av_p->parts_set);
- *slot = av_p;
- }
- else
- av_p = (struct aggregate_vardecl_d *) *slot;
-
- return av_p;
-}
-
-
-/* If STMT is a partial store into an aggregate, record which part got set. */
-
-static void
-dse_record_partial_aggregate_store (tree stmt, struct dse_global_data *dse_gd)
-{
- tree lhs, decl;
- enum tree_code code;
- struct aggregate_vardecl_d *av_p;
- int part;
-
- gcc_assert (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT);
-
- lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- code = TREE_CODE (lhs);
- if (code != IMAGPART_EXPR
- && code != REALPART_EXPR
- && code != COMPONENT_REF)
- return;
- decl = TREE_OPERAND (lhs, 0);
- /* Early bail on things like nested COMPONENT_REFs. */
- if (TREE_CODE (decl) != VAR_DECL)
- return;
- /* Early bail on unions. */
- if (code == COMPONENT_REF
- && TREE_CODE (TREE_TYPE (TREE_OPERAND (lhs, 0))) != RECORD_TYPE)
- return;
-
- av_p = get_aggregate_vardecl (decl, dse_gd, /*insert=*/false);
- /* Run away, this isn't an aggregate we care about. */
- if (!av_p || av_p->ignore)
- return;
-
- switch (code)
- {
- case IMAGPART_EXPR:
- part = 0;
- break;
- case REALPART_EXPR:
- part = 1;
- break;
- case COMPONENT_REF:
- {
- tree orig_field, fields;
- tree record_type = TREE_TYPE (TREE_OPERAND (lhs, 0));
-
- /* Get FIELD_DECL. */
- orig_field = TREE_OPERAND (lhs, 1);
-
- /* FIXME: Eeech, do this more efficiently. Perhaps
- calculate bit/byte offsets. */
- part = -1;
- fields = TYPE_FIELDS (record_type);
- while (fields)
- {
- ++part;
- if (fields == orig_field)
- break;
- fields = TREE_CHAIN (fields);
- }
- gcc_assert (part >= 0);
- }
- break;
- default:
- return;
}
+ /* We deliberately stop on clobbering statements and not only on
+ killing ones to make walking cheaper. Otherwise we can just
+ continue walking until both stores have equal reference trees. */
+ while (!stmt_may_clobber_ref_p (temp, gimple_assign_lhs (stmt)));
- /* Record which part was set. */
- SET_BIT (av_p->parts_set, part);
-}
-
-
-/* Return TRUE if all parts in an AGGREGATE_VARDECL have been set. */
-
-static inline bool
-dse_whole_aggregate_clobbered_p (struct aggregate_vardecl_d *av_p)
-{
- unsigned int i;
- sbitmap_iterator sbi;
- int nbits_set = 0;
-
- /* Count the number of partial stores (bits set). */
- EXECUTE_IF_SET_IN_SBITMAP (av_p->parts_set, 0, i, sbi)
- nbits_set++;
- return ((unsigned) nbits_set == av_p->nparts);
-}
-
-
-/* Return TRUE if STMT is a store into a whole aggregate whose parts we
- have already seen and recorded. */
-
-static bool
-dse_partial_kill_p (tree stmt, struct dse_global_data *dse_gd)
-{
- tree decl;
- struct aggregate_vardecl_d *av_p;
-
- /* Make sure this is a store into the whole. */
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
- {
- enum tree_code code;
-
- decl = GIMPLE_STMT_OPERAND (stmt, 0);
- code = TREE_CODE (TREE_TYPE (decl));
-
- if (code != COMPLEX_TYPE && code != RECORD_TYPE)
- return false;
-
- if (TREE_CODE (decl) != VAR_DECL)
- return false;
- }
- else
+ if (!is_gimple_assign (temp))
return false;
- av_p = get_aggregate_vardecl (decl, dse_gd, /*insert=*/false);
- gcc_assert (av_p != NULL);
+ *use_stmt = temp;
- return dse_whole_aggregate_clobbered_p (av_p);
+ return true;
}
@@ -610,136 +264,118 @@ dse_partial_kill_p (tree stmt, struct dse_global_data *dse_gd)
post dominates the first store, then the first store is dead. */
static void
-dse_optimize_stmt (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED,
- block_stmt_iterator bsi)
+dse_optimize_stmt (struct dse_global_data *dse_gd,
+ struct dse_block_local_data *bd,
+ gimple_stmt_iterator gsi)
{
- struct dse_block_local_data *bd
- = VEC_last (void_p, walk_data->block_data_stack);
- struct dse_global_data *dse_gd = walk_data->global_data;
- tree stmt = bsi_stmt (bsi);
- stmt_ann_t ann = stmt_ann (stmt);
+ gimple stmt = gsi_stmt (gsi);
/* If this statement has no virtual defs, then there is nothing
to do. */
- if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
+ if (!gimple_vdef (stmt))
return;
- /* We know we have virtual definitions. If this is a GIMPLE_MODIFY_STMT
+ /* We know we have virtual definitions. If this is a GIMPLE_ASSIGN
that's not also a function call, then record it into our table. */
- if (get_call_expr_in (stmt))
+ if (is_gimple_call (stmt) && gimple_call_fndecl (stmt))
return;
- if (ann->has_volatile_ops)
+ if (gimple_has_volatile_ops (stmt))
return;
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ if (is_gimple_assign (stmt))
{
- use_operand_p first_use_p = NULL_USE_OPERAND_P;
- use_operand_p use_p = NULL;
- tree use_stmt;
+ gimple use_stmt;
- if (!dse_possible_dead_store_p (stmt, &first_use_p, &use_p, &use_stmt,
- dse_gd, bd))
- return;
+ record_voperand_set (dse_gd->stores, &bd->stores, gimple_uid (stmt));
- /* If this is a partial store into an aggregate, record it. */
- dse_record_partial_aggregate_store (stmt, dse_gd);
-
- if (use_p != NULL_USE_OPERAND_P
- && bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
- && (!operand_equal_p (GIMPLE_STMT_OPERAND (stmt, 0),
- GIMPLE_STMT_OPERAND (use_stmt, 0), 0)
- && !dse_partial_kill_p (stmt, dse_gd))
- && memory_address_same (stmt, use_stmt))
- {
- /* If we have precisely one immediate use at this point, but
- the stores are not to the same memory location then walk the
- virtual def-use chain to get the stmt which stores to that same
- memory location. */
- if (get_use_of_stmt_lhs (stmt, &first_use_p, &use_p, &use_stmt) ==
- NULL_TREE)
- {
- record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
- return;
- }
- }
+ if (!dse_possible_dead_store_p (stmt, &use_stmt))
+ return;
/* If we have precisely one immediate use at this point and the
stores are to the same memory location or there is a chain of
virtual uses from stmt and the stmt which stores to that same
memory location, then we may have found redundant store. */
- if (use_p != NULL_USE_OPERAND_P
- && bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
- && (operand_equal_p (GIMPLE_STMT_OPERAND (stmt, 0),
- GIMPLE_STMT_OPERAND (use_stmt, 0), 0)
- || dse_partial_kill_p (stmt, dse_gd))
- && memory_address_same (stmt, use_stmt))
+ if (bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
+ && operand_equal_p (gimple_assign_lhs (stmt),
+ gimple_assign_lhs (use_stmt), 0))
{
- ssa_op_iter op_iter;
- def_operand_p var1;
- vuse_vec_p vv;
- tree stmt_lhs;
+ /* If use_stmt is or might be a nop assignment, e.g. for
+ struct { ... } S a, b, *p; ...
+ b = a; b = b;
+ or
+ b = a; b = *p; where p might be &b,
+ or
+ *p = a; *p = b; where p might be &b,
+ or
+ *p = *u; *p = *v; where p might be v, then USE_STMT
+ acts as a use as well as definition, so store in STMT
+ is not dead. */
+ if (stmt != use_stmt
+ && !is_gimple_reg (gimple_assign_rhs1 (use_stmt))
+ && !is_gimple_min_invariant (gimple_assign_rhs1 (use_stmt))
+ /* ??? Should {} be invariant? */
+ && gimple_assign_rhs_code (use_stmt) != CONSTRUCTOR
+ && refs_may_alias_p (gimple_assign_lhs (use_stmt),
+ gimple_assign_rhs1 (use_stmt)))
+ return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " Deleted dead store '");
- print_generic_expr (dump_file, bsi_stmt (bsi), dump_flags);
+ print_gimple_stmt (dump_file, gsi_stmt (gsi), dump_flags, 0);
fprintf (dump_file, "'\n");
}
/* Then we need to fix the operand of the consuming stmt. */
- stmt_lhs = USE_FROM_PTR (first_use_p);
- FOR_EACH_SSA_VDEF_OPERAND (var1, vv, stmt, op_iter)
- {
- tree usevar, temp;
-
- single_imm_use (DEF_FROM_PTR (var1), &use_p, &temp);
- gcc_assert (VUSE_VECT_NUM_ELEM (*vv) == 1);
- usevar = VUSE_ELEMENT_VAR (*vv, 0);
- SET_USE (use_p, usevar);
-
- /* Make sure we propagate the ABNORMAL bit setting. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (stmt_lhs))
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (usevar) = 1;
- }
+ unlink_stmt_vdef (stmt);
/* Remove the dead store. */
- bsi_remove (&bsi, true);
+ gsi_remove (&gsi, true);
/* And release any SSA_NAMEs set in this statement back to the
SSA_NAME manager. */
release_defs (stmt);
}
-
- record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
}
}
/* Record that we have seen the PHIs at the start of BB which correspond
to virtual operands. */
static void
-dse_record_phis (struct dom_walk_data *walk_data, basic_block bb)
+dse_record_phi (struct dse_global_data *dse_gd,
+ struct dse_block_local_data *bd,
+ gimple phi)
+{
+ if (!is_gimple_reg (gimple_phi_result (phi)))
+ record_voperand_set (dse_gd->stores, &bd->stores, get_stmt_uid (phi));
+}
+
+static void
+dse_enter_block (struct dom_walk_data *walk_data, basic_block bb)
{
struct dse_block_local_data *bd
- = VEC_last (void_p, walk_data->block_data_stack);
- struct dse_global_data *dse_gd = walk_data->global_data;
- tree phi;
-
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- if (!is_gimple_reg (PHI_RESULT (phi)))
- record_voperand_set (dse_gd->stores,
- &bd->stores,
- get_stmt_uid (phi));
+ = (struct dse_block_local_data *)
+ VEC_last (void_p, walk_data->block_data_stack);
+ struct dse_global_data *dse_gd
+ = (struct dse_global_data *) walk_data->global_data;
+ gimple_stmt_iterator gsi;
+
+ for (gsi = gsi_last (bb_seq (bb)); !gsi_end_p (gsi); gsi_prev (&gsi))
+ dse_optimize_stmt (dse_gd, bd, gsi);
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ dse_record_phi (dse_gd, bd, gsi_stmt (gsi));
}
static void
-dse_finalize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
+dse_leave_block (struct dom_walk_data *walk_data,
+ basic_block bb ATTRIBUTE_UNUSED)
{
struct dse_block_local_data *bd
- = VEC_last (void_p, walk_data->block_data_stack);
- struct dse_global_data *dse_gd = walk_data->global_data;
+ = (struct dse_block_local_data *)
+ VEC_last (void_p, walk_data->block_data_stack);
+ struct dse_global_data *dse_gd
+ = (struct dse_global_data *) walk_data->global_data;
bitmap stores = dse_gd->stores;
unsigned int i;
bitmap_iterator bi;
@@ -752,52 +388,6 @@ dse_finalize_block (struct dom_walk_data *walk_data,
}
}
-
-/* Hashing and equality functions for AGGREGATE_VARDECL. */
-
-static hashval_t
-aggregate_vardecl_hash (const void *p)
-{
- return htab_hash_pointer
- ((const void *)((const struct aggregate_vardecl_d *)p)->decl);
-}
-
-static int
-aggregate_vardecl_eq (const void *p1, const void *p2)
-{
- return ((const struct aggregate_vardecl_d *)p1)->decl
- == ((const struct aggregate_vardecl_d *)p2)->decl;
-}
-
-
-/* Free memory allocated by one entry in AGGREGATE_VARDECL. */
-
-static void
-aggregate_vardecl_free (void *p)
-{
- struct aggregate_vardecl_d *entry = (struct aggregate_vardecl_d *) p;
- sbitmap_free (entry->parts_set);
- free (entry);
-}
-
-
-/* Return true if STMT is a store into an entire aggregate. */
-
-static bool
-aggregate_whole_store_p (tree stmt)
-{
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
- {
- tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- enum tree_code code = TREE_CODE (TREE_TYPE (lhs));
-
- if (code == COMPLEX_TYPE || code == RECORD_TYPE)
- return true;
- }
- return false;
-}
-
-
/* Main entry point. */
static unsigned int
@@ -805,68 +395,27 @@ tree_ssa_dse (void)
{
struct dom_walk_data walk_data;
struct dse_global_data dse_gd;
- basic_block bb;
-
- dse_gd.aggregate_vardecl =
- htab_create (37, aggregate_vardecl_hash,
- aggregate_vardecl_eq, aggregate_vardecl_free);
-
- max_stmt_uid = 0;
- FOR_EACH_BB (bb)
- {
- block_stmt_iterator bsi;
-
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- tree stmt = bsi_stmt (bsi);
-
- /* Record aggregates which have been stored into as a whole. */
- if (aggregate_whole_store_p (stmt))
- {
- tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- if (TREE_CODE (lhs) == VAR_DECL)
- {
- struct aggregate_vardecl_d *av_p;
-
- av_p = get_aggregate_vardecl (lhs, &dse_gd, /*insert=*/true);
- av_p->ignore = false;
- /* Ignore aggregates with too many parts. */
- if (av_p->nparts > HOST_BITS_PER_LONG)
- av_p->ignore = true;
- }
- }
-
- /* Create a UID for each statement in the function.
- Ordering of the UIDs is not important for this pass. */
- stmt_ann (stmt)->uid = max_stmt_uid++;
- }
- }
+ renumber_gimple_stmt_uids ();
/* We might consider making this a property of each pass so that it
can be [re]computed on an as-needed basis. Particularly since
this pass could be seen as an extension of DCE which needs post
dominators. */
calculate_dominance_info (CDI_POST_DOMINATORS);
+ calculate_dominance_info (CDI_DOMINATORS);
/* Dead store elimination is fundamentally a walk of the post-dominator
tree and a backwards walk of statements within each block. */
- walk_data.walk_stmts_backward = true;
walk_data.dom_direction = CDI_POST_DOMINATORS;
walk_data.initialize_block_local_data = dse_initialize_block_local_data;
- walk_data.before_dom_children_before_stmts = NULL;
- walk_data.before_dom_children_walk_stmts = dse_optimize_stmt;
- walk_data.before_dom_children_after_stmts = dse_record_phis;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = dse_finalize_block;
- walk_data.interesting_blocks = NULL;
+ walk_data.before_dom_children = dse_enter_block;
+ walk_data.after_dom_children = dse_leave_block;
walk_data.block_local_data_size = sizeof (struct dse_block_local_data);
/* This is the main hash table for the dead store elimination pass. */
dse_gd.stores = BITMAP_ALLOC (NULL);
-
walk_data.global_data = &dse_gd;
/* Initialize the dominator walker. */
@@ -878,9 +427,8 @@ tree_ssa_dse (void)
/* Finalize the dominator walker. */
fini_walk_dominator_tree (&walk_data);
- /* Release unneeded data. */
+ /* Release the main bitmap. */
BITMAP_FREE (dse_gd.stores);
- htab_delete (dse_gd.aggregate_vardecl);
/* For now, just wipe the post-dominator information. */
free_dominance_info (CDI_POST_DOMINATORS);
@@ -893,7 +441,10 @@ gate_dse (void)
return flag_tree_dse != 0;
}
-struct tree_opt_pass pass_dse = {
+struct gimple_opt_pass pass_dse =
+{
+ {
+ GIMPLE_PASS,
"dse", /* name */
gate_dse, /* gate */
tree_ssa_dse, /* execute */
@@ -901,14 +452,13 @@ struct tree_opt_pass pass_dse = {
NULL, /* next */
0, /* static_pass_number */
TV_TREE_DSE, /* tv_id */
- PROP_cfg
- | PROP_ssa
- | PROP_alias, /* properties_required */
+ PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func
| TODO_ggc_collect
- | TODO_verify_ssa, /* todo_flags_finish */
- 0 /* letter */
+ | TODO_verify_ssa /* todo_flags_finish */
+ }
};
+