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* [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results @ 2022-06-22 9:03 dizhao at os dot amperecomputing.com 2022-06-22 11:52 ` [Bug tree-optimization/106054] " pinskia at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: dizhao at os dot amperecomputing.com @ 2022-06-22 9:03 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106054 Bug ID: 106054 Summary: Tree optimizations cause mcf generates incorrect results Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: dizhao at os dot amperecomputing.com Target Milestone: --- Created attachment 53189 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53189&action=edit test code in C Some tree optimization caused verification error on the spec2017 505.mcf test case. Attached is a small example I extracted, to help debugging the problem. When compiled with "-std=c99 -O2 -funroll-loops -fdisable-tree-slp1" the result is different with "-std=c99 -O2 -funroll-loops", the latter result is incorrect. (It is possible the problem is not slp itself. I haven't figured out the root cause by now.) Tested on trunk commit: 98b6e62cf5e7d477b5797084da59561f6d018668 . And the error seems to exist at least since trunk commit a1c9f779f75283427316b5c670c1e01ff8ce9ced. Thanks. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106054] Tree optimizations cause mcf generates incorrect results 2022-06-22 9:03 [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results dizhao at os dot amperecomputing.com @ 2022-06-22 11:52 ` pinskia at gcc dot gnu.org 2022-06-22 11:54 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-06-22 11:52 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106054 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Aliasing violations are present. Use -fno-strict-aliasing. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106054] Tree optimizations cause mcf generates incorrect results 2022-06-22 9:03 [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results dizhao at os dot amperecomputing.com 2022-06-22 11:52 ` [Bug tree-optimization/106054] " pinskia at gcc dot gnu.org @ 2022-06-22 11:54 ` pinskia at gcc dot gnu.org 2022-06-22 19:48 ` pinskia at gcc dot gnu.org 2022-06-23 3:38 ` dizhao at os dot amperecomputing.com 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-06-22 11:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106054 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It is the access via different pointer types. That is the issue. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106054] Tree optimizations cause mcf generates incorrect results 2022-06-22 9:03 [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results dizhao at os dot amperecomputing.com 2022-06-22 11:52 ` [Bug tree-optimization/106054] " pinskia at gcc dot gnu.org 2022-06-22 11:54 ` pinskia at gcc dot gnu.org @ 2022-06-22 19:48 ` pinskia at gcc dot gnu.org 2022-06-23 3:38 ` dizhao at os dot amperecomputing.com 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-06-22 19:48 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106054 --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >From https://www.spec.org/cpu2017/Docs/benchmarks/505.mcf_r.html: >The module spec_qsort.c does not obey strict ANSI aliasing rules. You may need to add your compiler's flag that informs it not to assume strict ANSI compliance. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106054] Tree optimizations cause mcf generates incorrect results 2022-06-22 9:03 [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results dizhao at os dot amperecomputing.com ` (2 preceding siblings ...) 2022-06-22 19:48 ` pinskia at gcc dot gnu.org @ 2022-06-23 3:38 ` dizhao at os dot amperecomputing.com 3 siblings, 0 replies; 5+ messages in thread From: dizhao at os dot amperecomputing.com @ 2022-06-23 3:38 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106054 --- Comment #4 from Di Zhao <dizhao at os dot amperecomputing.com> --- (In reply to Andrew Pinski from comment #3) > From https://www.spec.org/cpu2017/Docs/benchmarks/505.mcf_r.html: > >The module spec_qsort.c does not obey strict ANSI aliasing rules. You may need to add your compiler's flag that informs it not to assume strict ANSI compliance. I tried the "-fno-strict-aliasing" option and it works. Apologize for not noticing this. Thanks a lot! ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-06-23 3:38 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-06-22 9:03 [Bug tree-optimization/106054] New: Tree optimizations cause mcf generates incorrect results dizhao at os dot amperecomputing.com 2022-06-22 11:52 ` [Bug tree-optimization/106054] " pinskia at gcc dot gnu.org 2022-06-22 11:54 ` pinskia at gcc dot gnu.org 2022-06-22 19:48 ` pinskia at gcc dot gnu.org 2022-06-23 3:38 ` dizhao at os dot amperecomputing.com
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