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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/114009] [11/12/13/14 Regression] Missed optimization: (!a) * a => 0 when a=(a/2)*2 Date: Thu, 07 Mar 2024 07:47:04 +0000 [thread overview] Message-ID: <bug-114009-4-JLRXRlrjde@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-114009-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114009 --- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>: https://gcc.gnu.org/g:95b6ee96348041eaee9133f082b57f3e57ef0b11 commit r14-9350-g95b6ee96348041eaee9133f082b57f3e57ef0b11 Author: Jakub Jelinek <jakub@redhat.com> Date: Thu Mar 7 08:43:16 2024 +0100 match.pd: Optimize a * !a to 0 [PR114009] The following patch attempts to fix an optimization regression through adding a simple simplification. We already have the /* (m1 CMP m2) * d -> (m1 CMP m2) ? d : 0 */ (if (!canonicalize_math_p ()) (for cmp (tcc_comparison) (simplify (mult:c (convert (cmp@0 @1 @2)) @3) (if (INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (TREE_TYPE (@0))) (cond @0 @3 { build_zero_cst (type); }))) optimization which otherwise triggers during the a * !a multiplication, but that is done only late and we aren't able through range assumptions optimize it yet anyway. The patch adds a specific simplification for it. If a is zero, then a * !a will be 0 * 1 (or for signed 1-bit 0 * -1) and so 0. If a is non-zero, then a * !a will be a * 0 and so again 0. THe pattern is valid for scalar integers, complex integers and vector types, but I think will actually trigger only for the scalar integers. For vector types I've added other two with VEC_COND_EXPR in it, for complex there are different GENERIC trees to match and it is something that likely would be never matched in GIMPLE, so I didn't handle that. 2024-03-07 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/114009 * genmatch.cc (decision_tree::gen): Emit ARG_UNUSED for captures argument even for GENERIC, not just for GIMPLE. * match.pd (a * !a -> 0): New simplifications. * gcc.dg/tree-ssa/pr114009.c: New test.
next prev parent reply other threads:[~2024-03-07 7:47 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-02-20 10:16 [Bug tree-optimization/114009] New: " 652023330028 at smail dot nju.edu.cn 2024-02-20 23:50 ` [Bug tree-optimization/114009] " pinskia at gcc dot gnu.org 2024-02-20 23:56 ` [Bug tree-optimization/114009] [11/12/13/14 Regression] " pinskia at gcc dot gnu.org 2024-02-21 0:03 ` pinskia at gcc dot gnu.org 2024-02-22 10:21 ` rguenth at gcc dot gnu.org 2024-03-05 13:02 ` jakub at gcc dot gnu.org 2024-03-05 14:14 ` jakub at gcc dot gnu.org 2024-03-05 14:24 ` jakub at gcc dot gnu.org 2024-03-07 7:47 ` cvs-commit at gcc dot gnu.org [this message] 2024-03-15 9:45 ` jakub at gcc dot gnu.org
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