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From: "alonzakai at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug web/111694] New: Wrong behavior for signbit of negative zero when optimizing Date: Wed, 04 Oct 2023 17:09:16 +0000 [thread overview] Message-ID: <bug-111694-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111694 Bug ID: 111694 Summary: Wrong behavior for signbit of negative zero when optimizing Product: gcc Version: 13.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: web Assignee: unassigned at gcc dot gnu.org Reporter: alonzakai at gmail dot com Target Milestone: --- This behaves incorrectly in 13.2.0 with -O1 and above, but is correct in 12, 11, and 10. It is also correct in 13.2.0 without optimizations. Testcase: #include <math.h> #include <stdio.h> void test(double l, double r) { if (l == r && l == 0 && (signbit(l) || signbit(r))) { puts("one is negative"); } } int main() { test(0.0, -0.0); test(-0.0, 0.0); } This should print "one is negative" twice, but only does so once in 13.2.0 with -O1: $ gcc-13 a.c -O1 ; ./a.out one is negative $ gcc-13 a.c -O0 ; ./a.out one is negative one is negative $
next reply other threads:[~2023-10-04 17:09 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-04 17:09 alonzakai at gmail dot com [this message] 2023-10-04 18:31 ` [Bug tree-optimization/111694] [13/14 Regression] " amonakov at gcc dot gnu.org 2023-10-04 19:09 ` pinskia at gcc dot gnu.org 2023-10-05 7:37 ` rguenth at gcc dot gnu.org 2023-10-06 17:30 ` amacleod at redhat dot com 2023-10-09 17:10 ` cvs-commit at gcc dot gnu.org 2023-10-09 17:11 ` amacleod at redhat dot com 2023-10-09 17:18 ` amonakov at gcc dot gnu.org 2023-10-09 17:36 ` amacleod at redhat dot com 2023-10-09 19:37 ` amacleod at redhat dot com 2023-10-11 20:45 ` cvs-commit at gcc dot gnu.org 2023-10-11 20:48 ` amacleod at redhat dot com
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