{"id":2225606,"url":"http://patchwork.ozlabs.org/api/patches/2225606/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260421091714.AACEB4B9DB42@sourceware.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260421091714.AACEB4B9DB42@sourceware.org>","list_archive_url":null,"date":"2026-04-21T09:16:46","name":"tree-optimization/124946 - signed overflow with emulated mixed dot-prod","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"4c5248aa678d02c7dbfada5e920ad77e6beb98f0","submitter":{"id":4338,"url":"http://patchwork.ozlabs.org/api/people/4338/?format=json","name":"Richard Biener","email":"rguenther@suse.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260421091714.AACEB4B9DB42@sourceware.org/mbox/","series":[{"id":500765,"url":"http://patchwork.ozlabs.org/api/series/500765/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500765","date":"2026-04-21T09:16:46","name":"tree-optimization/124946 - signed overflow with emulated mixed dot-prod","version":1,"mbox":"http://patchwork.ozlabs.org/series/500765/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2225606/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2225606/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256\n header.s=susede2_rsa header.b=dINKBdZH;\n\tdkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=bDMKMKGK;\n\tdkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de\n header.a=rsa-sha256 header.s=susede2_rsa header.b=dINKBdZH;\n\tdkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=bDMKMKGK;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)","sourceware.org;\n\tdkim=pass (1024-bit key,\n unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256\n header.s=susede2_rsa header.b=dINKBdZH;\n\tdkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=bDMKMKGK;\n\tdkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de\n header.a=rsa-sha256 header.s=susede2_rsa header.b=dINKBdZH;\n\tdkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=bDMKMKGK","sourceware.org;\n dmarc=pass (p=none dis=none) header.from=suse.de","sourceware.org; spf=pass smtp.mailfrom=suse.de","server2.sourceware.org;\n arc=none smtp.remote-ip=195.135.223.130","smtp-out1.suse.de;\n\tnone"],"Received":["from vm01.sourceware.org (vm01.sourceware.org\n [IPv6:2620:52:6:3111::32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g0Gvy0xFlz1yGt\n\tfor ; Tue, 21 Apr 2026 19:17:16 +1000 (AEST)","from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id AACEB4B9DB42\n\tfor ; Tue, 21 Apr 2026 09:17:14 +0000 (GMT)","from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130])\n by sourceware.org (Postfix) with ESMTPS id 090C74BA2E10\n for ; Tue, 21 Apr 2026 09:16:48 +0000 (GMT)","from murzim.nue2.suse.org (unknown [10.168.4.243])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest\n SHA256)\n (No client certificate requested)\n by smtp-out1.suse.de (Postfix) with ESMTPS id BCEB36A80A\n for ; Tue, 21 Apr 2026 09:16:46 +0000 (UTC)"],"DKIM-Filter":["OpenDKIM Filter v2.11.0 sourceware.org AACEB4B9DB42","OpenDKIM Filter v2.11.0 sourceware.org 090C74BA2E10"],"DMARC-Filter":"OpenDMARC Filter v1.4.2 sourceware.org 090C74BA2E10","ARC-Filter":"OpenARC Filter v1.0.0 sourceware.org 090C74BA2E10","ARC-Seal":"i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1776763008; cv=none;\n b=WaRYxkdYn7zzdRHzZzQqV0C5AUfzPDCQM932YWw5/PfTu3VFyoGtaefHYJpMh7Ab4WgddBUpRZk8iSKMCvm+S0LOMebDhtaWH/pNiSn5FO6XBS0rCM0wFcQ9/jdhaPnUKfRXZhx1qecG/1abBlnE//8l97pWTwG63PuvnxFSTwQ=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776763008; c=relaxed/simple;\n bh=lGE+Uhv2NN9uNALKneAX+sw1zwUB65m/2jNMhfXonCY=;\n h=DKIM-Signature:DKIM-Signature:DKIM-Signature:DKIM-Signature:Date:\n From:To:Subject:MIME-Version;\n b=xZ8OhY/VPceF8JKhP7xYpVZZyQ4WtZGSn+VlqZFRq8tt9zc1GWpq9GCtdEXkuCbB1c5wMeCaTZWYaAcWDrXfdaH8+a/xOFqI3g/W2HyI4IWBBgoM6BfG0rUzCja7gkLemi9mTtkPCypLXA5IADKmCNbf4ghmZr337D0GrAiXo3A=","ARC-Authentication-Results":"i=1; server2.sourceware.org","DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de;\n s=susede2_rsa;\n t=1776763006;\n h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version:\n content-type:content-type; bh=RNc4hYRbD0eIa9swewsIZwlZygw0OsOQkmLTIKaddQM=;\n b=dINKBdZHKo/xLtjSyRXao0EfIbRKdGIMihHVUk3MoEedGGyDQwR1pEeA0xTYkdtfhT4oU0\n QvZFXnpg8Qn8EK8lafZpUOHTJH5oO5+Igbu8DodQfk9lKDkEf1UHvQQraMM7oCDnS1KLdP\n sKIZomIi3UZz7L6RvnW2FEo76RC1ZzA=","v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de;\n s=susede2_ed25519; t=1776763006;\n h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version:\n content-type:content-type; bh=RNc4hYRbD0eIa9swewsIZwlZygw0OsOQkmLTIKaddQM=;\n b=bDMKMKGKZYIziXd7hn2YA2+km4ZiYr0j1E7N2PageX5ArWwbeO0Ey5kIwAIvVteuSf8ite\n tnbWhvQgDlDDmjAg==","v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de;\n s=susede2_rsa;\n t=1776763006;\n h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version:\n content-type:content-type; bh=RNc4hYRbD0eIa9swewsIZwlZygw0OsOQkmLTIKaddQM=;\n b=dINKBdZHKo/xLtjSyRXao0EfIbRKdGIMihHVUk3MoEedGGyDQwR1pEeA0xTYkdtfhT4oU0\n QvZFXnpg8Qn8EK8lafZpUOHTJH5oO5+Igbu8DodQfk9lKDkEf1UHvQQraMM7oCDnS1KLdP\n sKIZomIi3UZz7L6RvnW2FEo76RC1ZzA=","v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de;\n s=susede2_ed25519; t=1776763006;\n h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version:\n content-type:content-type; bh=RNc4hYRbD0eIa9swewsIZwlZygw0OsOQkmLTIKaddQM=;\n b=bDMKMKGKZYIziXd7hn2YA2+km4ZiYr0j1E7N2PageX5ArWwbeO0Ey5kIwAIvVteuSf8ite\n tnbWhvQgDlDDmjAg=="],"Date":"Tue, 21 Apr 2026 11:16:46 +0200 (CEST)","From":"Richard Biener ","To":"gcc-patches@gcc.gnu.org","Subject":"[PATCH] tree-optimization/124946 - signed overflow with emulated\n mixed dot-prod","MIME-Version":"1.0","Content-Type":"text/plain; charset=US-ASCII","X-Spamd-Result":"default: False [-1.80 / 50.00]; BAYES_HAM(-3.00)[100.00%];\n MISSING_MID(2.50)[]; NEURAL_HAM_LONG(-1.00)[-0.998];\n NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain];\n TO_MATCH_ENVRCPT_ALL(0.00)[]; RCPT_COUNT_ONE(0.00)[1];\n MISSING_XM_UA(0.00)[]; FROM_EQ_ENVFROM(0.00)[];\n TO_DN_NONE(0.00)[]; ARC_NA(0.00)[]; RCVD_COUNT_ZERO(0.00)[0];\n FUZZY_RATELIMITED(0.00)[rspamd.com];\n DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519];\n MIME_TRACE(0.00)[0:+]; FROM_HAS_DN(0.00)[]","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org","Message-Id":"<20260421091714.AACEB4B9DB42@sourceware.org>"},"content":"When biasing the unsigned vector operand we have to perform that in\nan unsigned type to avoid possible signed overflow.\n\nBootstrapped and tested on x86_64-unknown-linux-gnu, queued for stage1.\n\n\tPR tree-optimization/124946\n\t* tree-vect-loop.cc (vect_emulate_mixed_dot_prod): Perform the\n\tconstant biasing in an unsigned type.\n---\n gcc/tree-vect-loop.cc | 20 ++++++++++++++------\n 1 file changed, 14 insertions(+), 6 deletions(-)","diff":"diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc\nindex 67a2be63e93..42fb4477d91 100644\n--- a/gcc/tree-vect-loop.cc\n+++ b/gcc/tree-vect-loop.cc\n@@ -7891,7 +7891,7 @@ vect_emulate_mixed_dot_prod (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,\n std::swap (vop[0], vop[1]);\n \n /* Convert all inputs to signed types. */\n- for (int i = 0; i < 3; ++i)\n+ for (int i = 1; i < 3; ++i)\n if (TYPE_UNSIGNED (TREE_TYPE (vop[i])))\n {\n \ttree tmp = make_ssa_name (signed_type_for (TREE_TYPE (vop[i])));\n@@ -7905,19 +7905,27 @@ vect_emulate_mixed_dot_prod (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,\n \n /* Create a vector of -128. */\n tree min_narrow_elttype = TYPE_MIN_VALUE (narrow_elttype);\n- tree min_narrow = build_vector_from_val (narrow_vectype,\n-\t\t\t\t\t min_narrow_elttype);\n+ tree min_narrow = build_vector_from_val (TREE_TYPE (vop[0]),\n+\t\t\t\t\t fold_convert\n+\t\t\t\t\t (TREE_TYPE (TREE_TYPE (vop[0])),\n+\t\t\t\t\t min_narrow_elttype));\n \n /* Create a vector of 64. */\n auto half_wi = wi::lrshift (wi::to_wide (min_narrow_elttype), 1);\n tree half_narrow = wide_int_to_tree (narrow_elttype, half_wi);\n half_narrow = build_vector_from_val (narrow_vectype, half_narrow);\n \n- /* Emit: SUB_RES = VOP[0] - 128. */\n- tree sub_res = make_ssa_name (narrow_vectype);\n+ /* Emit: SUB_RES = VOP[0] - 128 in an unsigned type. */\n+ tree sub_res = make_ssa_name (TREE_TYPE (vop[0]));\n new_stmt = gimple_build_assign (sub_res, PLUS_EXPR, vop[0], min_narrow);\n vect_finish_stmt_generation (loop_vinfo, stmt_info, new_stmt, gsi);\n \n+ vop[0] = make_ssa_name (narrow_vectype);\n+ new_stmt = gimple_build_assign (vop[0], VIEW_CONVERT_EXPR,\n+\t\t\t\t build1 (VIEW_CONVERT_EXPR, narrow_vectype,\n+\t\t\t\t\t sub_res));\n+ vect_finish_stmt_generation (loop_vinfo, stmt_info, new_stmt, gsi);\n+\n /* Emit:\n \n STAGE1 = DOT_PROD_EXPR ;\n@@ -7938,7 +7946,7 @@ vect_emulate_mixed_dot_prod (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,\n \n tree stage3 = make_ssa_name (wide_vectype);\n new_stmt = gimple_build_assign (stage3, DOT_PROD_EXPR,\n-\t\t\t\t sub_res, vop[1], stage2);\n+\t\t\t\t vop[0], vop[1], stage2);\n vect_finish_stmt_generation (loop_vinfo, stmt_info, new_stmt, gsi);\n \n /* Convert STAGE3 to the reduction type. */\n","prefixes":[]}