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[PATCH] Fix PR38851, missing DSE of zero-sized stores
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 26 Jan 2009 10:39:59 +0100 (CET)
- Subject: [PATCH] Fix PR38851, missing DSE of zero-sized stores
This fixes the annoying uninitialized warnings that occur with
zero-sized stores that result from initialization of empty C++ classes.
Fixed by extending simple DSE to remove these stores.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2009-01-24 Richard Guenther <rguenther@suse.de>
PR middle-end/38851
* Makefile.in (tree-ssa-dse.o): Add langhooks.h.
* tree-ssa-dse.c: Include langhooks.h
(execute_simple_dse): Remove stores with zero size.
* g++.dg/warn/Wuninitialized-1.C: New testcase.
Index: gcc/tree-ssa-dse.c
===================================================================
*** gcc/tree-ssa-dse.c.orig 2009-01-25 22:57:52.000000000 +0100
--- gcc/tree-ssa-dse.c 2009-01-25 22:58:07.000000000 +0100
*************** along with GCC; see the file COPYING3.
*** 34,39 ****
--- 34,40 ----
#include "tree-dump.h"
#include "domwalk.h"
#include "flags.h"
+ #include "langhooks.h"
/* This file implements dead store elimination.
*************** execute_simple_dse (void)
*** 660,679 ****
tree op;
bool removed = false;
ssa_op_iter iter;
! if (gimple_stored_syms (stmt)
! && !bitmap_empty_p (gimple_stored_syms (stmt))
! && (is_gimple_assign (stmt)
! || (is_gimple_call (stmt)
! && gimple_call_lhs (stmt)))
! && !bitmap_intersect_p (gimple_stored_syms (stmt), variables_loaded))
{
unsigned int i;
bitmap_iterator bi;
bool dead = true;
-
-
/* See if STMT only stores to write-only variables and
verify that there are no volatile operands. tree-ssa-operands
sets has_volatile_ops flag for all statements involving
--- 661,695 ----
tree op;
bool removed = false;
ssa_op_iter iter;
+ tree size;
! if (is_gimple_assign (stmt)
! && AGGREGATE_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
! && (size = lang_hooks.expr_size (gimple_assign_lhs (stmt)))
! && integer_zerop (size))
! {
! if (dump_file && (dump_flags & TDF_DETAILS))
! {
! fprintf (dump_file, " Deleted zero-sized store '");
! print_gimple_stmt (dump_file, stmt, 0, dump_flags);
! fprintf (dump_file, "'\n");
! }
! removed = true;
! gsi_remove (&gsi, true);
! todo |= TODO_cleanup_cfg;
! }
! else if (gimple_stored_syms (stmt)
! && !bitmap_empty_p (gimple_stored_syms (stmt))
! && (is_gimple_assign (stmt)
! || (is_gimple_call (stmt)
! && gimple_call_lhs (stmt)))
! && !bitmap_intersect_p (gimple_stored_syms (stmt),
! variables_loaded))
{
unsigned int i;
bitmap_iterator bi;
bool dead = true;
/* See if STMT only stores to write-only variables and
verify that there are no volatile operands. tree-ssa-operands
sets has_volatile_ops flag for all statements involving
Index: gcc/Makefile.in
===================================================================
*** gcc/Makefile.in.orig 2009-01-25 23:01:06.000000000 +0100
--- gcc/Makefile.in 2009-01-25 23:01:21.000000000 +0100
*************** tree-outof-ssa.o : tree-outof-ssa.c $(TR
*** 2110,2116 ****
tree-ssa-dse.o : tree-ssa-dse.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
$(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
$(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) domwalk.h $(FLAGS_H) \
! $(DIAGNOSTIC_H) $(TIMEVAR_H)
tree-ssa-forwprop.o : tree-ssa-forwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
$(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
$(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(TIMEVAR_H) \
--- 2110,2116 ----
tree-ssa-dse.o : tree-ssa-dse.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
$(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
$(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) domwalk.h $(FLAGS_H) \
! $(DIAGNOSTIC_H) $(TIMEVAR_H) langhooks.h
tree-ssa-forwprop.o : tree-ssa-forwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
$(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
$(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(TIMEVAR_H) \