[Bug tree-optimization/102872] If statement is always false but not figured out at gimple level

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102872

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
ifcombine makes

optimizing two comparisons to _13
Merging blocks 3 and 4

to

  <bb 3> [local count: 955630225]:
  d_10 = (short unsigned int) a.3_5;
  _9 = a.3_5 & 65535;
  _2 = d_10 != 0;
  _1 = _9 == 0;
  _13 = _1 & _2;
  if (_13 != 0)

so I wonder if we can simplify that somehow.  It looks like this could be
simplified to (a & 0xffff0000) != 0?