[Bug tree-optimization/114090] New: forwprop -fwrapv miscompilation

[kristerw at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114090

            Bug ID: 114090
           Summary: forwprop -fwrapv miscompilation
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kristerw at gcc dot gnu.org
  Target Milestone: ---

The function f below returns an incorrect result for INT_MIN when compiled with
-O1 -fwrapv for X86_64:


__attribute__((noipa)) int f(int x) {
    int w = (x >= 0 ? x : 0);
    int y = -x;
    int z = (y >= 0 ? y : 0);
    return w + z;
}

int
main ()
{
  if (f(0x80000000) != 0)
    __builtin_abort ();
  return 0;
}


What is happening is that forwprop has optimized

  w_2 = MAX_EXPR <x_1(D), 0>;
  y_3 = -x_1(D);
  z_4 = MAX_EXPR <y_3, 0>;
  _5 = w_2 + z_4;
  return _5;

to

  _5 = ABS_EXPR <x_1(D)>;
  return _5;