[Bug c/37544] New: Conversion double -> unsigned long long -> unsigned -> double gives wrong results

["jdemeyer at cage dot ugent dot be" <gcc-bugzilla at gcc dot gnu dot org>]

Consider the following line of the attached test case, where a is double with
value 4294967296.0.

double b = (unsigned int)((unsigned long long int)a % 4294967296ULL);

Then (unsigned long long int)a % 4294967296ULL should be equal to 0ULL, and
therefore b should be 0.0.  However, when compiled with -O1 -march=pentium4, b
gets the wrong value of 4294967296.0 (the same as a).  Note that the error only
occurs with -march=pentium4.

To compile the testcase:
gcc -std=c99 -O1 -march=pentium4 convert-bug.i -o convert-bug

gcc -v:
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc/configure --enable-checking=release
--prefix=/home/jdemeyer/local CC=gcc-4.1.2
Thread model: posix
gcc version 4.4.0 20080916 (experimental) (GCC)


-- 
           Summary: Conversion double -> unsigned long long -> unsigned ->
                    double gives wrong results
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jdemeyer at cage dot ugent dot be
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37544