[Bug tree-optimization/43000] New: [4.5 Regression] VRP miscompiles python with -fwrapv

[rguenth at gcc dot gnu dot org]

It miscompiles

                                if (need <= i) {

in filterstring inlined to builtin_filter in Python/bltinmodule.c.

Testcase:

int __attribute__((noinline))
foo (long i, long j)
{
  if (i >= 1)
    if (j > -9223372036854775807L)
      {
        long x;
        j--;
        x = i + j;
        if (x >= 0)
          return 1;
      }
  return 0;
}
int main()
{
  if (foo (1, 1) != 1)
    abort ();
  return 0;
}


-- 
           Summary: [4.5 Regression] VRP miscompiles python with -fwrapv
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43000