[Bug tree-optimization/53986] missing vrp on bit-mask test, LSHIFT_EXPR not handled

vries at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Sun Aug 5 18:16:00 GMT 2012


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53986

--- Comment #9 from vries at gcc dot gnu.org 2012-08-05 18:16:21 UTC ---
test-case for LSHIFT_EXPR vrp:
...
extern void link_error (void);

void
f3 (int s, int b)
{
  if (s >> 3 == -2)
    /* s in range [-16, -9].  */
    {
      s += 17;
      /* s in range [1, 8].  */
      b = (b & 1) + 1;
      /* b in range [1, 2].  */
      b =  b << s;
      /* b in range [bmin << smin, bmax << smax]
                    == [1 << 1, 2 << 8]
                    == [1, 512].  */
      if (b == 0|| b == 513)
        link_error ();
    }
}

int
main ()
{
  return 0;
}
...



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