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* [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging @ 2012-01-17 8:20 jakub at gcc dot gnu.org 2012-01-17 8:34 ` [Bug tree-optimization/51877] " jakub at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-17 8:20 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51877 Bug #: 51877 Summary: [4.7 Regression] XEmacs miscompilation due to tail merging Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: tree-optimization AssignedTo: jakub@gcc.gnu.org ReportedBy: jakub@gcc.gnu.org CC: vries@gcc.gnu.org extern void abort (void); struct A { int a; char b[32]; } a, b; __attribute__((noinline, noclone)) struct A bar (int x) { struct A r; static int n; r.a = ++n; __builtin_memset (r.b, 0, sizeof (r.b)); r.b[0] = x; return r; } __attribute__((noinline, noclone)) void baz (void) { asm volatile ("" : : : "memory"); } __attribute__((noinline, noclone)) void foo (struct A *x, int y) { if (y == 6) a = bar (7); else *x = bar (7); baz (); } int main () { a = bar (3); b = bar (4); if (a.a != 1 || a.b[0] != 3 || b.a != 2 || b.b[0] != 4) abort (); foo (&b, 0); if (a.a != 1 || a.b[0] != 3 || b.a != 3 || b.b[0] != 7) abort (); foo (&b, 6); if (a.a != 4 || a.b[0] != 7 || b.a != 3 || b.b[0] != 7) abort (); return 0; } is miscompiled at -O2 (distilled from XEmacs). Tail merging surprisingly decides to tail merge the two calls, eventhough they have different lhs. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51877] [4.7 Regression] XEmacs miscompilation due to tail merging 2012-01-17 8:20 [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging jakub at gcc dot gnu.org @ 2012-01-17 8:34 ` jakub at gcc dot gnu.org 2012-01-17 10:36 ` rguenth at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-17 8:34 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51877 --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-17 07:49:33 UTC --- Created attachment 26346 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26346 gcc47-pr51877.patch Untested fix. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51877] [4.7 Regression] XEmacs miscompilation due to tail merging 2012-01-17 8:20 [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging jakub at gcc dot gnu.org 2012-01-17 8:34 ` [Bug tree-optimization/51877] " jakub at gcc dot gnu.org @ 2012-01-17 10:36 ` rguenth at gcc dot gnu.org 2012-01-17 10:49 ` jakub at gcc dot gnu.org 2012-01-17 11:22 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2012-01-17 10:36 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51877 Richard Guenther <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2012-01-17 Target Milestone|--- |4.7.0 Ever Confirmed|0 |1 --- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-17 10:14:15 UTC --- Patch is ok. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51877] [4.7 Regression] XEmacs miscompilation due to tail merging 2012-01-17 8:20 [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging jakub at gcc dot gnu.org 2012-01-17 8:34 ` [Bug tree-optimization/51877] " jakub at gcc dot gnu.org 2012-01-17 10:36 ` rguenth at gcc dot gnu.org @ 2012-01-17 10:49 ` jakub at gcc dot gnu.org 2012-01-17 11:22 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-17 10:49 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51877 --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-17 10:38:43 UTC --- Author: jakub Date: Tue Jan 17 10:38:38 2012 New Revision: 183237 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183237 Log: PR tree-optimization/51877 * tree-ssa-tail-merge.c (gimple_equal_p): Don't return true whenever call arguments and fndecls compare equal, instead return false if they don't. Return true only if lhs1 and lhs2 are either both NULL, or both SSA_NAMEs that are valueized the same, or they satisfy operand_equal_p. * gcc.c-torture/execute/pr51877.c: New test. Added: trunk/gcc/testsuite/gcc.c-torture/execute/pr51877.c Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-ssa-tail-merge.c ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51877] [4.7 Regression] XEmacs miscompilation due to tail merging 2012-01-17 8:20 [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging jakub at gcc dot gnu.org ` (2 preceding siblings ...) 2012-01-17 10:49 ` jakub at gcc dot gnu.org @ 2012-01-17 11:22 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-17 11:22 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51877 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution| |FIXED --- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-17 11:07:51 UTC --- Fixed. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-01-17 11:11 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-01-17 8:20 [Bug tree-optimization/51877] New: [4.7 Regression] XEmacs miscompilation due to tail merging jakub at gcc dot gnu.org 2012-01-17 8:34 ` [Bug tree-optimization/51877] " jakub at gcc dot gnu.org 2012-01-17 10:36 ` rguenth at gcc dot gnu.org 2012-01-17 10:49 ` jakub at gcc dot gnu.org 2012-01-17 11:22 ` jakub at gcc dot gnu.org
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