[Bug tree-optimization/77387] New: Value range not computed in some cases for ABS_EXPR

[kugan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77387

            Bug ID: 77387
           Summary: Value range not computed in some cases for ABS_EXPR
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kugan at gcc dot gnu.org
  Target Milestone: ---

For testcase:

int foo (int i)
{
  int x = i;
  x = __builtin_abs (i);
  x >>= 24;
  if (x > 256)
    return 0;
  return x;
}

vrp1 dump is:
Value ranges after VRP:

_1: [-INF, 256]
i_2(D): VARYING
x_3: [0, +INF(OVF)]
x_4: VARYING
x_6: [257, +INF]  EQUIVALENCES: { x_4 } (1 elements)
x_7: [-INF, 256]  EQUIVALENCES: { x_4 } (1 elements)


Removing basic block 3
foo (int i)
{
  int x;
  int _1;

  <bb 2>:
  x_3 = ABS_EXPR <i_2(D)>;
  x_4 = x_3 >> 24;
  if (x_4 > 256)
    goto <bb 3>;
  else
    goto <bb 4>;

  <bb 3>:

  <bb 4>:
  # _1 = PHI <0(3), x_4(2)>
  return _1;

}


Note:
x_3: [0, +INF(OVF)]
x_4: VARYING