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From: "marxin at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/96633] missed optimization? Date: Mon, 17 Aug 2020 08:14:34 +0000 [thread overview] Message-ID: <bug-96633-4-n9Hctc5VP8@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-96633-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96633 Martin Liška <marxin at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2020-08-17 Status|UNCONFIRMED |NEW Keywords| |missed-optimization CC| |marxin at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> --- Nice trick! Generally speaking about the optimization (for longer types), it can be tricky as: shr $6, %ecx can be bigger than 64 and so shrq %cl, %rax can result in undefined behavior as 1 << X, where X > 64.
next prev parent reply other threads:[~2020-08-17 8:14 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-16 21:25 [Bug tree-optimization/96633] New: " nathan at gcc dot gnu.org 2020-08-17 8:14 ` marxin at gcc dot gnu.org [this message] 2020-08-17 12:07 ` [Bug tree-optimization/96633] " amonakov at gcc dot gnu.org 2020-08-20 11:36 ` marxin at gcc dot gnu.org 2021-07-21 1:05 ` [Bug middle-end/96633] " pinskia at gcc dot gnu.org
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