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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 middle-end/98865] Missed transform of (a >> 63) * b Date: Wed, 22 Sep 2021 18:19:16 +0000 [thread overview] Message-ID: <bug-98865-4-pwfengCu1D@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-98865-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98865 --- Comment #5 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:8f571e64713cc72561f84241863496e473eae4c6 commit r12-3824-g8f571e64713cc72561f84241863496e473eae4c6 Author: Roger Sayle <roger@nextmovesoftware.com> Date: Wed Sep 22 19:17:49 2021 +0100 More NEGATE_EXPR folding in match.pd As observed by Jakub in comment #2 of PR 98865, the expression -(a>>63) is optimized in GENERIC but not in GIMPLE. Investigating further it turns out that this is one of a few transformations performed by fold_negate_expr in fold-const.c that aren't yet performed by match.pd. This patch moves/duplicates them there, and should be relatively safe as these transformations are already performed by the compiler, but just in different passes. This revised patch adds a Boolean simplify argument to tree-ssa-sccvn.c's vn_nary_build_or_lookup_1 to control whether simplification should be performed before value numbering, updating the callers, but then avoiding simplification when constructing/value-numbering NEGATE_EXPR. This avoids the regression of gcc.dg/tree-ssa/ssa-free-88.c, and enables the new test case(s) to pass. 2021-09-22 Roger Sayle <roger@nextmovesoftware.com> Richard Biener <rguenther@suse.de> gcc/ChangeLog * match.pd (negation simplifications): Implement some negation folding transformations from fold-const.c's fold_negate_expr. * tree-ssa-sccvn.c (vn_nary_build_or_lookup_1): Add a SIMPLIFY argument, to control whether the op should be simplified prior to looking up/assigning a value number. (vn_nary_build_or_lookup): Update call to vn_nary_build_or_lookup_1. (vn_nary_simplify): Likewise. (visit_nary_op): Likewise, but when constructing a NEGATE_EXPR now call vn_nary_build_or_lookup_1 disabling simplification. gcc/testsuite/ChangeLog * gcc.dg/fold-negate-1.c: New test case.
next prev parent reply other threads:[~2021-09-22 18:19 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-28 13:38 [Bug middle-end/98865] New: " rguenth at gcc dot gnu.org 2021-01-28 13:40 ` [Bug middle-end/98865] " rguenth at gcc dot gnu.org 2021-01-28 14:26 ` jakub at gcc dot gnu.org 2021-03-07 2:46 ` pinskia at gcc dot gnu.org 2021-07-20 22:19 ` pinskia at gcc dot gnu.org 2021-09-22 18:19 ` cvs-commit at gcc dot gnu.org [this message] 2022-01-11 11:19 ` rguenth at gcc dot gnu.org 2022-05-18 15:24 ` cvs-commit at gcc dot gnu.org 2022-05-19 16:55 ` cvs-commit at gcc dot gnu.org 2022-05-27 8:02 ` cvs-commit at gcc dot gnu.org 2022-05-28 9:18 ` roger at nextmovesoftware dot com
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