{"id":2228697,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2228697/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260427081337.416B24BB24D9@sourceware.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/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},"msgid":"<20260427081337.416B24BB24D9@sourceware.org>","date":"2026-04-27T08:13:09","name":"tree-optimization/125025 - ICE with niter analysis and UBSAN","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"e4d8d3ae6886f511a912279a358db5afe4ee71eb","submitter":{"id":4338,"url":"http://patchwork.ozlabs.org/api/1.1/people/4338/?format=json","name":"Richard Biener","email":"rguenther@suse.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260427081337.416B24BB24D9@sourceware.org/mbox/","series":[{"id":501602,"url":"http://patchwork.ozlabs.org/api/1.1/series/501602/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=501602","date":"2026-04-27T08:13:09","name":"tree-optimization/125025 - ICE with niter analysis and UBSAN","version":1,"mbox":"http://patchwork.ozlabs.org/series/501602/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2228697/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2228697/checks/","tags":{},"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=BgHIXP0/;\n\tdkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=puAJuHEi;\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=BgHIXP0/;\n\tdkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=puAJuHEi;\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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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)[-0.994]; 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":"<20260427081337.416B24BB24D9@sourceware.org>"},"content":"The following avoids trying to compute the absolute step by\nnegating a signed step, instead, as done in one other place\nalready, first convert to unsigned and then negate.\n\nBootstrapped and tested on x86_64-unknown-linux-gnu, pushed.\n\n\tPR tree-optimization/125025\n\t* tree-ssa-loop-niter.cc (number_of_iterations_ne): Avoid\n\tnegation of most negative signed integer.\n\t(number_of_iterations_lt): Likewise.\n\n\t* gcc.dg/torture/pr125025.c: New testcase.\n---\n gcc/testsuite/gcc.dg/torture/pr125025.c | 20 ++++++++++++++++++++\n gcc/tree-ssa-loop-niter.cc | 8 ++++----\n 2 files changed, 24 insertions(+), 4 deletions(-)\n create mode 100644 gcc/testsuite/gcc.dg/torture/pr125025.c","diff":"diff --git a/gcc/testsuite/gcc.dg/torture/pr125025.c b/gcc/testsuite/gcc.dg/torture/pr125025.c\nnew file mode 100644\nindex 00000000000..ba156bb69d4\n--- /dev/null\n+++ b/gcc/testsuite/gcc.dg/torture/pr125025.c\n@@ -0,0 +1,20 @@\n+/* { dg-do compile } */\n+/* { dg-additional-options \"-fsanitize=undefined\" } */\n+\n+void f2(signed char a0)\n+{\n+ signed char v4;\n+ _Bool c7;\n+ signed char v8 = 91;\n+ v4 = v8 + v8;\n+ v8 = 15 - 50;\n+ a0 = v8 * v4;\n+ v8 = v4 - a0;\n+lbl_br10:\n+ c7 = a0 <= 0;\n+ if (c7)\n+ return;\n+ v4 = v8 - 24;\n+ a0 = a0 + v4;\n+ goto lbl_br10;\n+}\ndiff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc\nindex 2b4c4ea3da4..00c4a9c81f8 100644\n--- a/gcc/tree-ssa-loop-niter.cc\n+++ b/gcc/tree-ssa-loop-niter.cc\n@@ -988,8 +988,8 @@ number_of_iterations_ne (class loop *loop, tree type, affine_iv *iv,\n if BNDS->below in the result is nonnegative. */\n if (tree_int_cst_sign_bit (iv->step))\n {\n- s = fold_convert (niter_type,\n-\t\t\tfold_build1 (NEGATE_EXPR, type, iv->step));\n+ s = fold_build1 (NEGATE_EXPR, niter_type,\n+\t\t fold_convert (niter_type, iv->step));\n c = fold_build2 (MINUS_EXPR, niter_type,\n \t\t fold_convert (niter_type, iv->base),\n \t\t fold_convert (niter_type, final));\n@@ -1633,8 +1633,8 @@ number_of_iterations_lt (class loop *loop, tree type, affine_iv *iv0,\n if (integer_nonzerop (iv0->step))\n step = fold_convert (niter_type, iv0->step);\n else\n- step = fold_convert (niter_type,\n-\t\t\t fold_build1 (NEGATE_EXPR, type, iv1->step));\n+ step = fold_build1 (NEGATE_EXPR, niter_type,\n+\t\t\tfold_convert (niter_type, iv1->step));\n \n /* If we can determine the final value of the control iv exactly, we can\n transform the condition to != comparison. In particular, this will be\n","prefixes":[]}