public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [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
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).