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From: "shaohua.li at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/103406] New: gcc -O0 behaves differently on "DBL_MAX related operations" than gcc -O1 and above Date: Wed, 24 Nov 2021 11:09:30 +0000 [thread overview] Message-ID: <bug-103406-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103406 Bug ID: 103406 Summary: gcc -O0 behaves differently on "DBL_MAX related operations" than gcc -O1 and above Product: gcc Version: 11.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: shaohua.li at inf dot ethz.ch Target Milestone: --- Hi there, I found that for a piece of code, gcc would give out different results when compiled with different opt flags. - gcc version: 11.1.0 - Platform: Ubuntu 20.04, x86_64 $gcc a.c -O0; ./a.out nan $ $ $gcc a.c -O1; ./a.out -nan $ $ $cat a.c #include <stdio.h> #include <float.h> #define INFINITY (DBL_MAX+DBL_MAX) #define NAN (INFINITY-INFINITY) void main() { double x = -NAN; double y = NAN; double z = x + y; printf("%lf\n", z); }
next reply other threads:[~2021-11-24 11:09 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-24 11:09 shaohua.li at inf dot ethz.ch [this message] 2021-11-24 11:21 ` [Bug c/103406] " pinskia at gcc dot gnu.org 2021-11-24 11:23 ` ubizjak at gmail dot com 2021-11-24 11:29 ` pinskia at gcc dot gnu.org 2021-11-24 11:54 ` rguenth at gcc dot gnu.org 2021-11-24 12:01 ` rguenth at gcc dot gnu.org 2021-11-24 12:02 ` rguenth at gcc dot gnu.org 2021-11-24 12:03 ` [Bug middle-end/103406] [12 Regression] " rguenth at gcc dot gnu.org 2021-11-24 12:29 ` roger at nextmovesoftware dot com 2021-11-24 13:02 ` rguenth at gcc dot gnu.org 2021-11-24 13:04 ` rguenth at gcc dot gnu.org 2021-11-24 13:05 ` rguenth at gcc dot gnu.org 2021-11-24 22:22 ` joseph at codesourcery dot com 2021-11-25 19:04 ` cvs-commit at gcc dot gnu.org 2021-11-25 19:40 ` [Bug middle-end/103406] " roger at nextmovesoftware dot com 2021-11-25 20:29 ` joseph at codesourcery dot com 2021-11-26 17:58 ` roger at nextmovesoftware dot com
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