[Bug tree-optimization/99919] [9/10/11 Regression] bogus -Wmaybe-uninitialized with a _Bool bit-field

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99919

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |99918

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The IL below shows there is enough information in the IL for the warning to
determine that x_5 is never read from.

void g (struct B b)
{
  _Bool b$j;
  _Bool b$i;
  _Bool x;
  unsigned char _1;
  unsigned char _2;
  unsigned char _3;
  unsigned char _4;

  <bb 2> [local count: 1073741824]:
  b$i_11 = b.i;
  _1 = VIEW_CONVERT_EXPR<unsigned char>(b);
  _2 = _1 & 1;
  if (_2 != 0)
    goto <bb 4>; [50.00%]
  else
    goto <bb 3>; [50.00%]

  <bb 3> [local count: 536870912]:

  <bb 4> [local count: 1073741824]:
  # x_5 = PHI <x_8(D)(2), b$i_11(3)>
  # b$j_10 = PHI <0(2), b$i_11(3)>
  b.j = b$j_10;
  _3 = VIEW_CONVERT_EXPR<unsigned char>(b);
  _4 = _3 & 2;
  if (_4 != 0)
    goto <bb 5>; [50.00%]
  else
    goto <bb 6>; [50.00%]

  <bb 5> [local count: 536870913]:
  z = x_5;

  <bb 6> [local count: 1073741824]:
  return;

}


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99918
[Bug 99918] [9/10/11 Regression] suboptimal code for bool bitfield tests