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* [Bug tree-optimization/56962] [4.8/4.9 Regression] SLSR caused miscompilation of fftw
2013-04-15 8:25 [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw jakub at gcc dot gnu.org
@ 2013-04-15 8:25 ` jakub at gcc dot gnu.org
2013-04-15 10:15 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-04-15 8:25 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56962
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
CC| |wschmidt at gcc dot gnu.org
Target Milestone|--- |4.8.1
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw
@ 2013-04-15 8:25 jakub at gcc dot gnu.org
2013-04-15 8:25 ` [Bug tree-optimization/56962] " jakub at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-04-15 8:25 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56962
Bug #: 56962
Summary: [4.8/4.9 Regression] SLSR caused miscompilation of
fftw
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: jakub@gcc.gnu.org
Reduced testcase:
extern void abort (void);
long double v[144];
__attribute__((noinline, noclone)) void
bar (long double *x)
{
if (x != &v[29])
abort ();
}
__attribute__((noinline, noclone)) void
foo (long double *x, long y, long z)
{
long double a, b, c;
a = x[z * 4 + y * 3];
b = x[z * 5 + y * 3];
c = x[z * 5 + y * 4];
x[y * 4] = a;
bar (&x[z * 5 + y]);
x[z * 5 + y * 5] = b + c;
}
int
main ()
{
foo (v, 24, 1);
return 0;
}
This fails at -O2, works with -O2 -fno-tree-slsr. Started with
http://gcc.gnu.org/r190220
The *.reassoc2 to *.slsr diff with unimportant stuff removed:
...
_2 = z_1(D) * 4;
_4 = y_3(D) * 3;
_5 = _2 + _4;
...
_12 = z_1(D) * 5;
- _13 = _4 + _12;
+ _13 = _5 + z_1(D);
...
_18 = y_3(D) * 4;
- _19 = _12 + _18;
+ _19 = _13 + y_3(D);
...
- _28 = y_3(D) + _12;
+ _28 = _19 - _5;
...
Here before slsr we have:
_5 = y*3+z*4
_13 = y*3+z*5
_19 = y*4+z*5
_28 = y+z*5
and the _13 and _19 changes look just fine, but the _28 change is changing the
value from y+z*5 to y+z.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/56962] [4.8/4.9 Regression] SLSR caused miscompilation of fftw
2013-04-15 8:25 [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw jakub at gcc dot gnu.org
2013-04-15 8:25 ` [Bug tree-optimization/56962] " jakub at gcc dot gnu.org
@ 2013-04-15 10:15 ` jakub at gcc dot gnu.org
2013-04-15 13:19 ` wschmidt at gcc dot gnu.org
2013-04-15 15:02 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-04-15 10:15 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56962
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2013-04-15
AssignedTo|unassigned at gcc dot |jakub at gcc dot gnu.org
|gnu.org |
Ever Confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-15 10:15:16 UTC ---
Created attachment 29873
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29873
gcc49-pr56962.patch
Untested fix. CAND_ADD can apparently be set even on c->cand_stmt which isn't
a addition (e.g. cast of the addition etc.), plus by just silently assuming
that if rhs1 isn't equal to c->base_expr, then rhs2 is, doesn't work in all
cases.
In particular, c->cand_stmt can be e.g. addition of two SSA_NAMEs where each
one of those adds in some part, not equal to c->base_expr.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/56962] [4.8/4.9 Regression] SLSR caused miscompilation of fftw
2013-04-15 8:25 [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw jakub at gcc dot gnu.org
2013-04-15 8:25 ` [Bug tree-optimization/56962] " jakub at gcc dot gnu.org
2013-04-15 10:15 ` jakub at gcc dot gnu.org
@ 2013-04-15 13:19 ` wschmidt at gcc dot gnu.org
2013-04-15 15:02 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: wschmidt at gcc dot gnu.org @ 2013-04-15 13:19 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56962
--- Comment #2 from Bill Schmidt <wschmidt at gcc dot gnu.org> 2013-04-15 13:19:53 UTC ---
The fix looks correct to me. Thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/56962] [4.8/4.9 Regression] SLSR caused miscompilation of fftw
2013-04-15 8:25 [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw jakub at gcc dot gnu.org
` (2 preceding siblings ...)
2013-04-15 13:19 ` wschmidt at gcc dot gnu.org
@ 2013-04-15 15:02 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-04-15 15:02 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56962
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-15 15:02:43 UTC ---
Author: jakub
Date: Mon Apr 15 14:56:36 2013
New Revision: 197978
URL: http://gcc.gnu.org/viewcvs?rev=197978&root=gcc&view=rev
Log:
PR tree-optimization/56962
* gimple-ssa-strength-reduction.c (record_increment): Only set
initializer if gimple_assign_rhs_code is {,POINTER_}PLUS_EXPR and
either rhs1 or rhs2 is equal to c->base_expr.
* gcc.c-torture/execute/pr56962.c: New test.
Added:
trunk/gcc/testsuite/gcc.c-torture/execute/pr56962.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/gimple-ssa-strength-reduction.c
trunk/gcc/testsuite/ChangeLog
Author: jakub
Date: Mon Apr 15 15:00:06 2013
New Revision: 197979
URL: http://gcc.gnu.org/viewcvs?rev=197979&root=gcc&view=rev
Log:
PR tree-optimization/56962
* gimple-ssa-strength-reduction.c (record_increment): Only set
initializer if gimple_assign_rhs_code is {,POINTER_}PLUS_EXPR and
either rhs1 or rhs2 is equal to c->base_expr.
* gcc.c-torture/execute/pr56962.c: New test.
Added:
branches/gcc-4_8-branch/gcc/testsuite/gcc.c-torture/execute/pr56962.c
Modified:
branches/gcc-4_8-branch/gcc/ChangeLog
branches/gcc-4_8-branch/gcc/gimple-ssa-strength-reduction.c
branches/gcc-4_8-branch/gcc/testsuite/ChangeLog
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2013-04-15 8:25 [Bug tree-optimization/56962] New: [4.8/4.9 Regression] SLSR caused miscompilation of fftw jakub at gcc dot gnu.org
2013-04-15 8:25 ` [Bug tree-optimization/56962] " jakub at gcc dot gnu.org
2013-04-15 10:15 ` jakub at gcc dot gnu.org
2013-04-15 13:19 ` wschmidt at gcc dot gnu.org
2013-04-15 15:02 ` jakub at gcc dot gnu.org
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