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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/63743] Thumb1: big regression for float operators by r216728 Date: Wed, 05 Nov 2014 08:35:00 -0000 [thread overview] Message-ID: <bug-63743-4-Lbsnr15WoI@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-63743-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63743 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Were we swapping operands before? I mean, if you rewrite the testcase to swap the * arguments in the source, did you get the same more efficient code in the past? In any case, this doesn't sound something that we should keep in mind in GIMPLE passes, + and * are just commutative, how they are expanded is a matter of expansion. So, either look for this during expansion (if a commutative operation is being expanded using libcall (or is this emitted by the backend?), see if one of the operands isn't result of immediately preceeding emitted call and if it is, perhaps swap the order of arguments), or add some register allocator smarts (add a way to mark library calls as commutative and allow RA to swap arguments to them if beneficial).
next prev parent reply other threads:[~2014-11-05 8:35 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-11-05 8:20 [Bug tree-optimization/63743] New: " zhenqiang.chen at arm dot com 2014-11-05 8:35 ` jakub at gcc dot gnu.org [this message] 2014-11-05 9:40 ` [Bug tree-optimization/63743] " zhenqiang.chen at arm dot com 2014-11-05 9:51 ` jakub at gcc dot gnu.org 2014-11-05 10:21 ` zhenqiang.chen at arm dot com 2014-11-05 12:34 ` rguenth at gcc dot gnu.org 2014-12-26 13:54 ` ysrumyan at gmail dot com 2015-01-15 14:56 ` rguenth at gcc dot gnu.org 2015-01-28 8:01 ` thopre01 at gcc dot gnu.org 2015-03-04 6:58 ` thopre01 at gcc dot gnu.org 2015-03-09 1:32 ` thopre01 at gcc dot gnu.org 2015-03-11 5:06 ` thopre01 at gcc dot gnu.org
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