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From: "juzhe.zhong at rivai dot ai" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/112457] New: Possible better vectorization of different reduction min/max reduction Date: Thu, 09 Nov 2023 12:27:50 +0000 [thread overview] Message-ID: <bug-112457-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112457 Bug ID: 112457 Summary: Possible better vectorization of different reduction min/max reduction Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: juzhe.zhong at rivai dot ai Target Milestone: --- Hi, Richard. GCC-14 almost has all features of RVV. I am planning to participate on improving GCC loop vectorizer in GCC-15. Fix FAILs of TSVC is one of my plan. Currently we can vectorize this following case: int idx = 0; int max = 0; void foo (int n, int * __restrict a){ for (int i = 0; i < n; ++i) { max = max < a[i] ? a[i] : max; } } However, if we change this case it failed: void foo2 (int n, int * __restrict a){ for (int i = 0; i < n; ++i) { if (max < a[i]) { max = a[i]; } else max = max; } } Now, I notice another interesting and possible vectorization enhancement which inspired by this patch of LLVM: https://reviews.llvm.org/D143465 And more advance case is which is case from LLVM patch: which is vectorization reduction with index: void foo3 (int n, int * __restrict a){ for (int i = 0; i < n; ++i) { if (max < a[i]) { idx = i; max = a[i]; } } } I wonder it is a valuable optimization ? If yes, it would be one of my TODO list. Thanks.
next reply other threads:[~2023-11-09 12:27 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-09 12:27 juzhe.zhong at rivai dot ai [this message] 2023-11-09 12:29 ` [Bug c/112457] " juzhe.zhong at rivai dot ai 2023-11-09 12:45 ` [Bug tree-optimization/112457] " rguenth at gcc dot gnu.org 2024-01-02 8:58 ` juzhe.zhong at rivai dot ai 2024-01-02 16:03 ` xry111 at gcc dot gnu.org 2024-01-08 9:00 ` rguenth at gcc dot gnu.org
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