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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/101895] [11/12 Regression] SLP Vectorizer change pushes VEC_PERM_EXPR into bad location spoiling further optimization opportunities Date: Tue, 15 Mar 2022 09:06:45 +0000 [thread overview] Message-ID: <bug-101895-4-ENJA856ihq@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-101895-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101895 --- Comment #6 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:49fb0af9bf8f16907980d383c2bbc85e185ec2e0 commit r12-7653-g49fb0af9bf8f16907980d383c2bbc85e185ec2e0 Author: Roger Sayle <roger@nextmovesoftware.com> Date: Tue Mar 15 09:05:28 2022 +0000 PR tree-optimization/101895: Fold VEC_PERM to help recognize FMA. This patch resolves PR tree-optimization/101895 a missed optimization regression, by adding a costant folding simplification to match.pd to simplify the transform "mult; vec_perm; plus" into "vec_perm; mult; plus" with the aim that keeping the multiplication and addition next to each other allows them to be recognized as fused-multiply-add on suitable targets. This transformation requires a tweak to match.pd's vec_same_elem_p predicate to handle CONSTRUCTOR_EXPRs using the same SSA_NAME_DEF_STMT idiom used for constructors elsewhere in match.pd. The net effect is that the following code example: void foo(float * __restrict__ a, float b, float *c) { a[0] = c[0]*b + a[0]; a[1] = c[2]*b + a[1]; a[2] = c[1]*b + a[2]; a[3] = c[3]*b + a[3]; } when compiled on x86_64-pc-linux-gnu with -O2 -march=cascadelake currently generates: vbroadcastss %xmm0, %xmm0 vmulps (%rsi), %xmm0, %xmm0 vpermilps $216, %xmm0, %xmm0 vaddps (%rdi), %xmm0, %xmm0 vmovups %xmm0, (%rdi) ret but with this patch now generates the improved: vpermilps $216, (%rsi), %xmm1 vbroadcastss %xmm0, %xmm0 vfmadd213ps (%rdi), %xmm0, %xmm1 vmovups %xmm1, (%rdi) ret 2022-03-15 Roger Sayle <roger@nextmovesoftware.com> Marc Glisse <marc.glisse@inria.fr> Richard Biener <rguenther@suse.de> gcc/ChangeLog PR tree-optimization/101895 * match.pd (vec_same_elem_p): Handle CONSTRUCTOR_EXPR def. (plus (vec_perm (mult ...) ...) ...): New reordering simplification. gcc/testsuite/ChangeLog PR tree-optimization/101895 * gcc.target/i386/pr101895.c: New test case.
next prev parent reply other threads:[~2022-03-15 9:06 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-13 5:01 [Bug tree-optimization/101895] New: " law at gcc dot gnu.org 2021-08-13 5:24 ` [Bug tree-optimization/101895] " pinskia at gcc dot gnu.org 2021-08-13 5:24 ` pinskia at gcc dot gnu.org 2021-08-16 7:49 ` rguenth at gcc dot gnu.org 2021-08-25 4:40 ` law at gcc dot gnu.org 2021-08-25 7:19 ` rguenth at gcc dot gnu.org 2022-03-11 23:51 ` roger at nextmovesoftware dot com 2022-03-15 9:06 ` cvs-commit at gcc dot gnu.org [this message] 2022-03-15 23:44 ` roger at nextmovesoftware dot com 2022-03-16 7:10 ` [Bug tree-optimization/101895] [11 " rguenth at gcc dot gnu.org 2022-03-16 23:13 ` law at gcc dot gnu.org 2022-03-17 23:18 ` law at gcc dot gnu.org 2022-04-21 7:50 ` rguenth at gcc dot gnu.org 2023-05-29 10:05 ` jakub at gcc dot gnu.org
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