public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "jwzeng at nuaa dot edu.cn" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/110410] New: [14 Regression] Different results between -O0 and -O2 Date: Mon, 26 Jun 2023 09:38:55 +0000 [thread overview] Message-ID: <bug-110410-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110410 Bug ID: 110410 Summary: [14 Regression] Different results between -O0 and -O2 Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: jwzeng at nuaa dot edu.cn Target Milestone: --- The following code snippet: #include <stdio.h> int seed; void hash(int *seed, int v) { *seed ^= v; } unsigned int var_6 = 1341494070U; int var_7 = 0; unsigned short var_8 = 7472; int var_13 = 518868156U; unsigned var_17; #define min(a, b) ((a) < (b) ? (a) : (b)) void test() { for (int ii_0 = 0; ii_0 < 20; ++ii_0) for (int ii_1 = 0; ii_1 < 10; ++ii_1) var_17 = min(var_6 ? var_8 >> (var_13 - 518868145U) : var_7, 1887837879 || 0); } int main() { test(2062689408U); hash(&seed, var_17); printf("%d\n", seed); return 0; } > $ /usr/gcc-trunk/bin/gcc -O0 bug.c; ./a.out > 1 > $ /usr/gcc-trunk/bin/gcc -O2 bug.c; ./a.out > 3 When compiled with -O2 or -O3, it prints 3 instead of 1. Earlier GCCs do not have this bug. > $ /usr/gcc-trunk/bin/gcc --version gcc (GCC) 14.0.0 20230619 (experimental) [master r14-1917-gf8e0270272] Copyright (C) 2023 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
next reply other threads:[~2023-06-26 9:38 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-26 9:38 jwzeng at nuaa dot edu.cn [this message] 2023-06-26 10:11 ` [Bug tree-optimization/110410] " jwzeng at nuaa dot edu.cn 2023-06-26 11:37 ` rguenth at gcc dot gnu.org 2023-06-26 12:32 ` jwzeng at nuaa dot edu.cn 2023-06-26 15:58 ` pinskia at gcc dot gnu.org 2023-06-26 16:07 ` pinskia at gcc dot gnu.org 2023-06-26 21:32 ` pinskia at gcc dot gnu.org 2023-07-19 16:19 ` pinskia at gcc dot gnu.org 2023-07-19 16:36 ` [Bug tree-optimization/110410] Missed optimization in DOM with a single value range pinskia at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-110410-4@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).