From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id DEC313858C2B for ; Thu, 20 Jul 2023 16:59:00 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org DEC313858C2B Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 43B0D2F4; Thu, 20 Jul 2023 09:59:43 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.110.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DAF83F6C4; Thu, 20 Jul 2023 09:58:59 -0700 (PDT) From: Richard Sandiford To: Richard Biener Mail-Followup-To: Richard Biener ,Richard Biener via Gcc-patches , richard.sandiford@arm.com Cc: Richard Biener via Gcc-patches Subject: Re: [PATCH] tree-optimization/110742 - fix latent issue with permuting existing vectors References: Date: Thu, 20 Jul 2023 17:58:58 +0100 In-Reply-To: (Richard Biener's message of "Thu, 20 Jul 2023 16:57:50 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-26.5 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Richard Biener writes: >> Am 20.07.2023 um 16:09 schrieb Richard Sandiford : >>=20 >> =EF=BB=BFRichard Biener via Gcc-patches writes: >>> When we materialize a layout we push edge permutes to constant/external >>> defs without checking we can actually do so. For externals defined >>> by vector stmts rather than scalar components we can't. >>>=20 >>> Bootstrapped and tested on x86_64-unknown-linux-gnu. >>>=20 >>> OK? >>>=20 >>> Thanks, >>> Richard. >>>=20 >>> PR tree-optimization/110742 >>> * tree-vect-slp.cc (vect_optimize_slp_pass::get_result_with_layout): >>> Do not materialize an edge permutation in an external node with >>> vector defs. >>> (vect_slp_analyze_node_operations_1): Guard purely internal >>> nodes better. >>>=20 >>> * g++.dg/torture/pr110742.C: New testcase. >>> --- >>> gcc/testsuite/g++.dg/torture/pr110742.C | 47 +++++++++++++++++++++++++ >>> gcc/tree-vect-slp.cc | 8 +++-- >>> 2 files changed, 53 insertions(+), 2 deletions(-) >>> create mode 100644 gcc/testsuite/g++.dg/torture/pr110742.C >>>=20 >>> diff --git a/gcc/testsuite/g++.dg/torture/pr110742.C b/gcc/testsuite/g+= +.dg/torture/pr110742.C >>> new file mode 100644 >>> index 00000000000..d41ac0479d2 >>> --- /dev/null >>> +++ b/gcc/testsuite/g++.dg/torture/pr110742.C >>> @@ -0,0 +1,47 @@ >>> +// { dg-do compile } >>> + >>> +struct HARD_REG_SET { >>> + HARD_REG_SET operator~() const { >>> + HARD_REG_SET res; >>> + for (unsigned int i =3D 0; i < (sizeof(elts) / sizeof((elts)[0]));= ++i) >>> + res.elts[i] =3D ~elts[i]; >>> + return res; >>> + } >>> + HARD_REG_SET operator&(const HARD_REG_SET &other) const { >>> + HARD_REG_SET res; >>> + for (unsigned int i =3D 0; i < (sizeof(elts) / sizeof((elts)[0]));= ++i) >>> + res.elts[i] =3D elts[i] & other.elts[i]; >>> + return res; >>> + } >>> + unsigned long elts[4]; >>> +}; >>> +typedef const HARD_REG_SET &const_hard_reg_set; >>> +inline bool hard_reg_set_subset_p(const_hard_reg_set x, const_hard_reg= _set y) { >>> + unsigned long bad =3D 0; >>> + for (unsigned int i =3D 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])= ); ++i) >>> + bad |=3D (x.elts[i] & ~y.elts[i]); >>> + return bad =3D=3D 0; >>> +} >>> +inline bool hard_reg_set_empty_p(const_hard_reg_set x) { >>> + unsigned long bad =3D 0; >>> + for (unsigned int i =3D 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])= ); ++i) >>> + bad |=3D x.elts[i]; >>> + return bad =3D=3D 0; >>> +} >>> +extern HARD_REG_SET rr[2]; >>> +extern int t[2]; >>> +extern HARD_REG_SET nn; >>> +static HARD_REG_SET mm; >>> +void setup_reg_class_relations(void) { >>> + HARD_REG_SET intersection_set, union_set, temp_set2; >>> + for (int cl2 =3D 0; cl2 < 2; cl2++) { >>> + temp_set2 =3D rr[cl2] & ~nn; >>> + if (hard_reg_set_empty_p(mm) && hard_reg_set_empty_p(temp_set2)) { >>> + mm =3D rr[0] & nn; >>> + if (hard_reg_set_subset_p(mm, intersection_set)) >>> + if (!hard_reg_set_subset_p(mm, temp_set2) || >>> + hard_reg_set_subset_p(rr[0], rr[t[cl2]])) >>> + t[cl2] =3D 0; >>> + } >>> + } >>> +} >>> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc >>> index 693621ca990..1d79c77e8ce 100644 >>> --- a/gcc/tree-vect-slp.cc >>> +++ b/gcc/tree-vect-slp.cc >>> @@ -5198,7 +5198,10 @@ vect_optimize_slp_pass::get_result_with_layout (= slp_tree node, >>> return result; >>>=20 >>> if (SLP_TREE_DEF_TYPE (node) =3D=3D vect_constant_def >>> - || SLP_TREE_DEF_TYPE (node) =3D=3D vect_external_def) >>> + || (SLP_TREE_DEF_TYPE (node) =3D=3D vect_external_def >>> + && (to_layout_i =3D=3D 0 >>> + /* We can't permute vector defs. */ >>> + || SLP_TREE_VEC_DEFS (node).is_empty ()))) >>=20 >> Guess it's personal preference, but IMO it's easier to follow without the >> to_layout_i condition, so that it ties directly to the create_partitions >> test. > > I don=E2=80=99t understand- in the code guarding this we seem to expect t= o_layout_i =3D=3D 0 and that=E2=80=99s the case we can handle as noop. I d= idn=E2=80=99t understand why the function doesn=E2=80=99t always just do no= thing in this case though, so I must have missed something. OK, so I guess that disproves that my way is easier to understand :) I think logically, the code is doing the equivalent of: int partition_i =3D m_vertices[node->vertex].partition; if (partition < 0) { /* If the vector is uniform or unchanged, there's nothing to do. */ ...=20=20=20=20=20=20 } else { ... Return node if to_layout_i matches this partition's chosen layout= ... } And I guess I should have written it that way. So when there is no partition, we have a constant or external def built from individual scalars. We can use the node as-is if the caller wants an unpermuted node or if all elements are equal (so that the permutation doesn't matter). Otherwise we need to permute the scalars. When there is a partition, we can use the node as-is if the caller wants the layout that was chosen for that partition. Otherwise we need a new VEC_PERM_EXPR node. In the particular case of external defs built from vectors, we're guaranteed that the node's chosen layout is 0 (i.e. the original layout), and so both ways work. But in principle this case fits the "else" arm better than the "then" arm, because we're dealing with a node that is in a partition, and that is not built from scalars. Thanks, Richard