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 4E30B3856946 for ; Tue, 21 Jun 2022 15:15:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4E30B3856946 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 90E4C165C; Tue, 21 Jun 2022 08:15:22 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.98.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E7A533F66F; Tue, 21 Jun 2022 08:15:21 -0700 (PDT) From: Richard Sandiford To: gcc-patches@gcc.gnu.org Mail-Followup-To: gcc-patches@gcc.gnu.org, rguenther@suse.de, richard.sandiford@arm.com Cc: rguenther@suse.de Subject: [PATCH] data-ref: Improve non-loop disambiguation [PR106019] Date: Tue, 21 Jun 2022 16:15:20 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-56.9 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 X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jun 2022 15:15:25 -0000 When dr_may_alias_p is called without a loop context, it tries to use the tree-affine interface to calculate the difference between the two addresses and use that difference to check whether the gap between the accesses is known at compile time. However, as the example in the PR shows, this doesn't expand SSA_NAMEs and so can easily be defeated by things like reassociation. One fix would have been to use aff_combination_expand to expand the SSA_NAMEs, but we'd then need some way of maintaining the associated cache. This patch instead reuses the innermost_loop_behavior fields (which exist even when no loop context is provided). It might still be useful to do the aff_combination_expand thing too, if an example turns out to need it. Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install? Richard gcc/ PR tree-optimization/106019 * tree-data-ref.cc (dr_may_alias_p): Try using the innermost_loop_behavior to disambiguate non-loop queries. gcc/testsuite/ PR tree-optimization/106019 * gcc.dg/vect/bb-slp-pr106019.c: New test. --- gcc/testsuite/gcc.dg/vect/bb-slp-pr106019.c | 15 +++++++++++++++ gcc/tree-data-ref.cc | 19 +++++++++++++++++++ 2 files changed, 34 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/vect/bb-slp-pr106019.c diff --git a/gcc/testsuite/gcc.dg/vect/bb-slp-pr106019.c b/gcc/testsuite/gcc.dg/vect/bb-slp-pr106019.c new file mode 100644 index 00000000000..218d7cca33d --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/bb-slp-pr106019.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ + +void f(double *p, long i) +{ + p[i+0] += 1; + p[i+1] += 1; +} +void g(double *p, long i) +{ + double *q = p + i; + q[0] += 1; + q[1] += 1; +} + +/* { dg-final { scan-tree-dump-not "can't determine dependence" slp2 } } */ diff --git a/gcc/tree-data-ref.cc b/gcc/tree-data-ref.cc index 8b7edf2124a..90242948c27 100644 --- a/gcc/tree-data-ref.cc +++ b/gcc/tree-data-ref.cc @@ -2968,6 +2968,25 @@ dr_may_alias_p (const struct data_reference *a, const struct data_reference *b, disambiguation. */ if (!loop_nest) { + tree tree_size_a = TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (a))); + tree tree_size_b = TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (b))); + + if (DR_BASE_ADDRESS (a) + && DR_BASE_ADDRESS (b) + && operand_equal_p (DR_BASE_ADDRESS (a), DR_BASE_ADDRESS (b)) + && operand_equal_p (DR_OFFSET (a), DR_OFFSET (b)) + && poly_int_tree_p (tree_size_a) + && poly_int_tree_p (tree_size_b) + && !ranges_maybe_overlap_p (wi::to_widest (DR_INIT (a)), + wi::to_widest (tree_size_a), + wi::to_widest (DR_INIT (b)), + wi::to_widest (tree_size_b))) + { + gcc_assert (integer_zerop (DR_STEP (a)) + && integer_zerop (DR_STEP (b))); + return false; + } + aff_tree off1, off2; poly_widest_int size1, size2; get_inner_reference_aff (DR_REF (a), &off1, &size1); -- 2.25.1