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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/96392] Optimize x+0.0 if x is an integer Date: Wed, 09 Feb 2022 14:24:02 +0000 [thread overview] Message-ID: <bug-96392-4-a4lQrobH5f@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-96392-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96392 --- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>: https://gcc.gnu.org/g:2d3c477599b02b06e338acd5f5098ee7a3fe6176 commit r12-7130-g2d3c477599b02b06e338acd5f5098ee7a3fe6176 Author: Roger Sayle <roger@nextmovesoftware.com> Date: Wed Feb 9 14:21:08 2022 +0000 [PATCH] PR tree-optimization/104420: Fix checks for constant folding X*0.0 This patch resolves PR tree-optimization/104420, which is a P1 regression where, as observed by Jakub Jelinek, the conditions for constant folding x*0.0 are incorrect (following my patch for PR tree-optimization/96392). The multiplication x*0.0 may yield a negative zero result, -0.0, if X is negative (not just if x may be negative zero). Hence (without -ffast-math) (int)x*0.0 can't be optimized to 0.0, but (unsigned)x*0.0 can be constant folded. This adds a bunch of test cases to confirm the desired behaviour, and removes an incorrect test from gcc.dg/pr96392.c which checked for the wrong behaviour. 2022-02-09 Roger Sayle <roger@nextmovesoftware.com> gcc/ChangeLog PR tree-optimization/104420 * match.pd (mult @0 real_zerop): Tweak conditions for constant folding X*0.0 (or X*-0.0) to HONOR_SIGNED_ZEROS when appropriate. gcc/testsuite/ChangeLog PR tree-optimization/104420 * gcc.dg/pr104420-1.c: New test case. * gcc.dg/pr104420-2.c: New test case. * gcc.dg/pr104420-3.c: New test case. * gcc.dg/pr104420-4.c: New test case. * gcc.dg/pr96392.c: Remove incorrect test.
prev parent reply other threads:[~2022-02-09 14:24 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-30 19:08 [Bug tree-optimization/96392] New: " hugo_musso_gualandi at hotmail dot com 2020-07-30 20:34 ` [Bug tree-optimization/96392] " glisse at gcc dot gnu.org 2021-06-11 16:18 ` cvs-commit at gcc dot gnu.org 2021-06-11 16:43 ` cvs-commit at gcc dot gnu.org 2021-07-10 8:37 ` roger at nextmovesoftware dot com 2022-02-09 14:24 ` cvs-commit at gcc dot gnu.org [this message]
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