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From: "udifuchs at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/56608] New: built-in floor function returns false results when build with -ffast-math
Date: Wed, 13 Mar 2013 02:55:00 -0000	[thread overview]
Message-ID: <bug-56608-4@http.gcc.gnu.org/bugzilla/> (raw)


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56608

             Bug #: 56608
           Summary: built-in floor function returns false results when
                    build with -ffast-math
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: udifuchs@gmail.com


In some cases floor() seems to return 0 value even if its argument is larger
than 1. This happens when compiling with '-O3 -ffast-math'.

Attached is the smallest code I found, which reproduces the problem. The
comments in the code explain how to reproduces the problem. There is also an
example of how a small tweak hides the problem.

Udi


             reply	other threads:[~2013-03-13  2:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-13  2:55 udifuchs at gmail dot com [this message]
2013-03-13  2:56 ` [Bug c/56608] " udifuchs at gmail dot com
2013-03-13  3:27 ` [Bug tree-optimization/56608] SLP seems to produce incorrect value " pinskia at gcc dot gnu.org
2013-03-13  9:08 ` [Bug tree-optimization/56608] [4.7/4.8 Regression] " rguenth at gcc dot gnu.org
2013-03-13 10:44 ` rguenth at gcc dot gnu.org
2013-03-13 12:16 ` rguenth at gcc dot gnu.org
2013-03-13 13:16 ` [Bug tree-optimization/56608] [4.7 " rguenth at gcc dot gnu.org
2013-03-26 10:16 ` rguenth at gcc dot gnu.org

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