[Bug c/56608] New: built-in floor function returns false results when build with -ffast-math

[udifuchs at gmail dot com]

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: unassig...@gcc.gnu.org

        ReportedBy: udifu...@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