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* [Bug target/47759] New: _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations @ 2011-02-15 21:58 siarhei.siamashka at gmail dot com 2011-02-15 21:58 ` [Bug target/47759] " pinskia at gcc dot gnu.org 2011-02-15 22:21 ` pinskia at gcc dot gnu.org 0 siblings, 2 replies; 3+ messages in thread From: siarhei.siamashka at gmail dot com @ 2011-02-15 21:58 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47759 Summary: _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations Product: gcc Version: 4.5.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned@gcc.gnu.org ReportedBy: siarhei.siamashka@gmail.com Host: i686-pc-linux-gnu Created attachment 23355 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23355 mm_empty_testcase.c The attached testcase fails when compiled with -O2 or -O3 optimizations, but works with -O1. I'm actually not precisely sure how this code is expected to behave because intrinsics are x86 architecture specific and C standard can't be used as a reference. But my guess is that if the optimizer would not be allowed to arbitrarily move code across _mm_empty() boundary, then the problem would disappear. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/47759] _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations 2011-02-15 21:58 [Bug target/47759] New: _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations siarhei.siamashka at gmail dot com @ 2011-02-15 21:58 ` pinskia at gcc dot gnu.org 2011-02-15 22:21 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2011-02-15 21:58 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47759 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2011.02.15 21:57:56 Ever Confirmed|0 |1 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-02-15 21:57:56 UTC --- Confirmed, the scheduler does not know that the mmx instructions touch the x87 registers. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/47759] _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations 2011-02-15 21:58 [Bug target/47759] New: _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations siarhei.siamashka at gmail dot com 2011-02-15 21:58 ` [Bug target/47759] " pinskia at gcc dot gnu.org @ 2011-02-15 22:21 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2011-02-15 22:21 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47759 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-02-15 21:59:12 UTC --- Note this is a target specific issue and not a generic scheduler issue as the target does not communicate to the scheduler that the x87 registers and the MMX register overlap. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-02-15 21:59 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-02-15 21:58 [Bug target/47759] New: _mm_empty() intrinsic fails to serve as a boundary between MMX and x87 code due to optimizations siarhei.siamashka at gmail dot com 2011-02-15 21:58 ` [Bug target/47759] " pinskia at gcc dot gnu.org 2011-02-15 22:21 ` pinskia at gcc dot gnu.org
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