Re: [EXTERNAL] [PATCH] testsuite: Fix up tree-ssa/pr103514.c testcase [PR103514]

[Jakub Jelinek <jakub@redhat.com>]

On Sun, Jan 30, 2022 at 10:16:44AM +0000, Navid Rahimi via Gcc-patches wrote:
> Thanks Jakob for the correction. Sadly, I didn’t have any access to any non x86 architecture. But x86 was fully tested and there was no regression.
> 
> In my spare time I will look at implementation of this for short-circuit targets.

Note, it isn't just about those targets.
If you write the code as:
_Bool
g (_Bool a, _Bool b)
{
  _Bool c;
  if (!a)
    c = 0;
  else if (!b)
    c = 0;
  else
    c = 1;
  return c == (a ^ b); 
}
instead, it will not match either, not even on x86, even when it is
equivalent.

Though, maybe for non-short-circuiting targets we should recognize this
somewhere and turn into c = a & b;

Since phiopt2 it is:
  <bb 2> [local count: 1073741824]:
  if (a_4(D) != 0)
    goto <bb 3>; [50.00%]
  else
    goto <bb 4>; [50.00%]

  <bb 3> [local count: 536870913]:
  _8 = (int) b_5(D);

  <bb 4> [local count: 1073741824]:
  # iftmp.0_3 = PHI <_8(3), 0(2)>
and phiopt3 makes
  <bb 2> [local count: 1073741824]:
  if (a_4(D) != 0)
    goto <bb 3>; [50.00%]
  else
    goto <bb 4>; [50.00%]

  <bb 3> [local count: 536870913]:

  <bb 4> [local count: 1073741824]:
  # _9 = PHI <b_5(D)(3), 0(2)>
  iftmp.0_3 = (int) _9;
out of that.

CCing Andrew if he'd like to have a look for GCC 13.

	Jakub