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[Bug tree-optimization/43716] [4.6 Regression] Revision 158105 miscompiles doduc.f90
- From: "dominiq at lps dot ens dot fr" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 13 Apr 2010 14:09:01 -0000
- Subject: [Bug tree-optimization/43716] [4.6 Regression] Revision 158105 miscompiles doduc.f90
- References: <bug-43716-12313@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #12 from dominiq at lps dot ens dot fr 2010-04-13 14:09 -------
A few additional notes:
(1) with revision 158105 reverted, the test gcc.dg/tree-ssa/reassoc-19.c fails
with -m32, but passes with -m64.
(2) revision 158265 with/without revision 158105 reverted (after some surgery
to replace plus_negates with broken_up_subtracts) also miscompiles doduc.f90.
(3) Following comment #10, is it possible to rule out a critical loss of
precision due to the reassociation?
(4) From Jerry Delisle, the diff before and after r158105 on fedora is
$ diff s33022.s.before s33022.s.after
315c315
< subsd 296(%rsp), %xmm14
---
> subsd 288(%rsp), %xmm14
321c321
< subsd 288(%rsp), %xmm14
---
> subsd 296(%rsp), %xmm14
458c458
< xorpd .LC12(%rip), %xmm12
---
> mulsd 384(%rsp), %xmm15
461,462d460
< mulsd 384(%rsp), %xmm15
< subsd 368(%rsp), %xmm12
467d464
< mulsd 232(%rsp), %xmm12
499,501c496,498
< movsd 296(%rsp), %xmm3
< subsd 272(%rsp), %xmm3
< subsd %xmm12, %xmm15
---
> movsd 368(%rsp), %xmm3
> xorpd .LC12(%rip), %xmm3
> subsd %xmm12, %xmm3
504c501
< mulsd %xmm8, %xmm3
---
> mulsd 232(%rsp), %xmm3
505a503,506
> subsd %xmm3, %xmm15
> movsd 296(%rsp), %xmm3
> subsd 272(%rsp), %xmm3
> mulsd %xmm8, %xmm3
--
dominiq at lps dot ens dot fr changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |matz at suse dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43716