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GET /api/patches/2225606/?format=api
{ "id": 2225606, "url": "http://patchwork.ozlabs.org/api/patches/2225606/?format=api", "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=api", "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=api", "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=api", "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": "<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>", "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; 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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 <rguenther@suse.de>", "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 <gcc-patches.gcc.gnu.org>", "List-Unsubscribe": "<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>", "List-Archive": "<https://gcc.gnu.org/pipermail/gcc-patches/>", "List-Post": "<mailto:gcc-patches@gcc.gnu.org>", "List-Help": "<mailto:gcc-patches-request@gcc.gnu.org?subject=help>", "List-Subscribe": "<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>", "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 <VOP[1], 64, VOP[2]>;\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": [] }