[Bug tree-optimization/71417] New: wrong code (SIGFPE) at -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71417

            Bug ID: 71417
           Summary: wrong code (SIGFPE) at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The current gcc trunk miscompiles the following code on x86_64-linux-gnu at -O3
in both 32-bit and 64-bit modes.

This is a regression from 6.1.x. 


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160604 (experimental) [trunk revision 237091] (GCC) 
$ 
$ gcc-trunk -O2 small.c; ./a.out
$ gcc-6.1 -O3 small.c; ./a.out
$ 
$ gcc-trunk -O3 small.c
$ ./a.out
Floating point exception (core dumped)
$ 


---------------------------------------


char a = -97;
int b, c, d, e;

int
main ()
{
  int g = d, h = 0, i = 1; 
  for (; h < 3; h++)
    {
      if (g > -1)
        {
          int j;
          g = j = 0;
          for (; j < 5; j++)
          L1:
            if (!i)
              goto L1;
          a = e;
        }
      else
        i = 0;
    }
  b = c / ~(a | 114);
  return 0; 
}