From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 734FA385772A; Wed, 26 Jul 2023 09:34:51 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 734FA385772A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1690364091; bh=Btw0Md75rrpxWgRrBaKfWCk2NB46fXykc4pJhW8YM2w=; h=From:To:Subject:Date:In-Reply-To:References:From; b=diMan4mIgd08DOLdtADtBEVdCu0Lz43cCbE5VPJG6QzQ0kavFau9W5tZQ8gZvw+il orxs9BmZwZThdaqYNet5QQTh6phkvyVShuDNC4FUcJPLSH3OS6FKlzUegLF5b5mQpF My1peF4OYm6evj9Kdo60Oh9TZ61temdkV9IWxqW0= From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/106081] missed vectorization Date: Wed, 26 Jul 2023 09:34:48 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106081 --- Comment #9 from Richard Biener --- So I can adjust change_layout_cost in a bit awkward way, but it seems that internal_node_cost would already work out that a permute can be merged into an existing permute. It seems that existing permutes are not recorded in the "layout". Also vectorizable_slp_permutation_1 doesn't try to elide permutes that are noop based on knowledge of the layout of 'node', say a permute { 1 0 3 2 } of a { _1, _1, _2, _2 } node would be noop. But change_layout_cost does MAX (count, 1) on its result anyway. The following elides the unnecessary permutation for this special case (but not the general case): diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc index e4430248ab5..e9048a61891 100644 --- a/gcc/tree-vect-slp.cc +++ b/gcc/tree-vect-slp.cc @@ -4389,6 +4389,19 @@ vect_optimize_slp_pass::change_layout_cost (slp_tree node, if (from_layout_i =3D=3D to_layout_i) return 0; + /* When there's a uniform load permutation permutating that in any + way is free. */ + if (SLP_TREE_LOAD_PERMUTATION (node).exists ()) + { + unsigned l =3D SLP_TREE_LOAD_PERMUTATION (node)[0]; + unsigned i; + for (i =3D 1; i < SLP_TREE_LOAD_PERMUTATION (node).length (); ++i) + if (SLP_TREE_LOAD_PERMUTATION (node)[i] !=3D l) + break; + if (i =3D=3D SLP_TREE_LOAD_PERMUTATION (node).length ()) + return 0; + } + auto_vec children (1); children.quick_push (node); auto_lane_permutation_t perm (SLP_TREE_LANES (node)); I'm not sure this is the correct place to factor in cost savings materialization would give. Is it? Are explicit VEC_PERM nodes also still there in the optimization process or are they turned into sth implicit?=