[Bug c/57209] New: Wrong code of print statement

[ishiura-compiler at ml dot kwansei.ac.jp]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57209

             Bug #: 57209
           Summary: Wrong code of print statement
    Classification: Unclassified
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ishiura-compiler@ml.kwansei.ac.jp


The following code is miscompiled by GCC 4.8.1 20130508 (prerelease)
for x86_64 (as well as for i686).  The option in question is
"-funsafe-math-optimizations."

  $ cat error.c

  volatile char buff = 0;
  void PRINTF(const char* s)
  {
    while(*s++) buff = *s;
  }

  int main (void)
  {
    int k = -1;
    int t = 1 % (int)(( 942.0 + k ) / -941.0F );
    if (t == 0) { PRINTF("OK"); }
    return 0;
  }

  $ x86_64-unknown-linux-gnu-gcc-4.8.1 error.c -O1 -funsafe-math-optimizations
  $ ./a.out
  Floating point exception (core dumped)

-----

$ x86_64-unknown-linux-gnu-gcc-4.8.1 -v
Using built-in specs.
COLLECT_GCC=x86_64-unknown-linux-gnu-gcc-4.8.1
COLLECT_LTO_WRAPPER=/usr/local/x86_64-tools/gcc-4.8.1/libexec/gcc/x86_64-unknown-linux-gnu/4.8.1/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /home/hassy/gcc/configure
--prefix=/usr/local/x86_64-tools/gcc-4.8.1/
--with-gmp=/usr/local/gmp-5.1.1/ --with-mpfr=/usr/local/mpfr-3.1.2/
--with-mpc=/usr/local/mpc-1.0.1/ --disable-multilib --disable-nls
--enable-languages=c
Thread model: posix
gcc version 4.8.1 20130508 (prerelease) (GCC)