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From: "vincenzo.innocente at cern dot ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/109011] New: missed optimization in presence of __builtin_ctz Date: Fri, 03 Mar 2023 14:56:19 +0000 [thread overview] Message-ID: <bug-109011-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109011 Bug ID: 109011 Summary: missed optimization in presence of __builtin_ctz Product: gcc Version: 12.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: vincenzo.innocente at cern dot ch Target Milestone: --- in the following code foo does not vectorize, bar does. clang vectorize foo using a pattern that invokes vplzcntd (code made a bit complex to make vectorization "relevant") see https://godbolt.org/z/5fa1zbPeG #include <cstdint> uint32_t x[256]; uint32_t y[256]; uint32_t w[256]; uint32_t z[256]; void foo() { for (int i=0; i<256;i++) { auto p = x[i] ? __builtin_ctz(x[i]) : y[i]; z[i] = w[i]*p; } } void bar() { for (int j=0; j<256;j+=8) for (int i=j; i<j+8;i++) { // auto p = x[i] ? x[i] : y[i]; auto p = x[i] ? __builtin_ctz(x[i]) : y[i]; z[i] = w[i]*p; } }
next reply other threads:[~2023-03-03 14:56 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-03 14:56 vincenzo.innocente at cern dot ch [this message] 2023-03-03 19:45 ` [Bug tree-optimization/109011] " pinskia at gcc dot gnu.org 2023-03-03 19:48 ` pinskia at gcc dot gnu.org 2023-03-03 20:21 ` jakub at gcc dot gnu.org 2023-03-03 20:39 ` jakub at gcc dot gnu.org 2023-03-03 20:46 ` jakub at gcc dot gnu.org 2023-03-04 0:18 ` jakub at gcc dot gnu.org 2023-03-04 11:14 ` jakub at gcc dot gnu.org 2023-03-04 12:22 ` jakub at gcc dot gnu.org 2023-03-04 14:01 ` jakub at gcc dot gnu.org 2023-03-04 15:08 ` jakub at gcc dot gnu.org 2023-03-06 5:26 ` crazylht at gmail dot com 2023-03-06 7:01 ` jakub at gcc dot gnu.org 2023-03-06 7:59 ` crazylht at gmail dot com 2023-03-06 8:11 ` jakub at gcc dot gnu.org 2023-03-06 8:23 ` crazylht at gmail dot com 2023-03-06 8:32 ` jakub at gcc dot gnu.org 2023-03-06 9:22 ` jakub at gcc dot gnu.org 2023-03-14 9:24 ` crazylht at gmail dot com 2023-03-16 6:32 ` crazylht at gmail dot com 2023-04-19 9:15 ` cvs-commit at gcc dot gnu.org 2023-04-20 9:56 ` cvs-commit at gcc dot gnu.org 2023-04-20 17:45 ` cvs-commit at gcc dot gnu.org 2023-04-24 1:35 ` cvs-commit at gcc dot gnu.org
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