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[PATCH] Fix PR53085
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Tue, 24 Apr 2012 16:39:23 +0200 (CEST)
- Subject: [PATCH] Fix PR53085
This fixes redundant store elimination in FRE/PRE to preserve
volatile stores.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to the
trunk and the branch.
Richard.
2012-04-24 Richard Guenther <rguenther@suse.de>
PR tree-optimization/53085
* tree-ssa-pre.c (eliminate): Do not eliminate volatile redundant
stores.
* g++.dg/torture/pr53085.C: New testcase.
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c (revision 186761)
--- gcc/tree-ssa-pre.c (working copy)
*************** eliminate (void)
*** 4409,4414 ****
--- 4409,4415 ----
has the same value number as its rhs. If so, the store is
dead. */
else if (gimple_assign_single_p (stmt)
+ && !gimple_has_volatile_ops (stmt)
&& !is_gimple_reg (gimple_assign_lhs (stmt))
&& (TREE_CODE (rhs) == SSA_NAME
|| is_gimple_min_invariant (rhs)))
Index: gcc/testsuite/g++.dg/torture/pr53085.C
===================================================================
*** gcc/testsuite/g++.dg/torture/pr53085.C (revision 0)
--- gcc/testsuite/g++.dg/torture/pr53085.C (revision 0)
***************
*** 0 ****
--- 1,17 ----
+ // { dg-do compile }
+ // { dg-skip-if "" { *-*-* } { "-fno-fat-lto-objects" } { "" } }
+ // { dg-options "-fdump-tree-optimized" }
+
+ class aa{
+ void f();
+ private:
+ volatile int a;
+ };
+
+ void aa::f(){
+ a=1;
+ a=1;
+ }
+
+ // { dg-final { scan-tree-dump-times "a ={v} 1;" 2 "optimized" } }
+ // { dg-final { cleanup-tree-dump "optimized" } }