[Bug tree-optimization/102844] [9/10/11/12 Regression] gcc-9.x miscompiles unsigned char expression in switch

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102844

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Before:
  <bb 13> [local count: 25265782]:
<L4>:
  nd.7_11 = _46;
  _12 = _46 + -128;
  _13 = (unsigned char) _12;
  dic = _13;
  goto <bb 15>; [100.00%]

  <bb 14> [local count: 25265782]:
<L5>:
  dic = 0;

  <bb 15> [local count: 114848370]:
  # nd_52 = PHI <nd_6(14), 149(12), nd_6(13), 33(8)>
  return nd_52;

  <bb 16> [local count: 25270028]:
  _46 = (signed char) nd_6;
  if (_46 < 0)
    goto <bb 13>; [33.33%]
  else
    goto <bb 14>; [66.67%]


Hmmm:

  <bb 16> [local count: 25270028]:
  nd_36 = ASSERT_EXPR <nd_47, nd_47 <= 130>;
  _46 = (signed char) nd_36;
  if (_46 < 0)
    goto <bb 21>; [33.33%]
  else
    goto <bb 20>; [66.67%]


  <bb 21> [local count: 8423438]:
  _17 = ASSERT_EXPR <_46, _46 < 0>;
  nd_39 = ASSERT_EXPR <nd_36, nd_36 + 128 <= 127>;

  <bb 13> [local count: 25265782]:
<L4>:
  nd.7_11 = _34(D);
  _12 = _33(D) + -128;
  _13 = (unsigned char) _12;
  dic = _13;
  goto <bb 15>; [100.00%]

  <bb 20> [local count: 16846590]:
  nd_45 = ASSERT_EXPR <nd_36, nd_36 + 128 > 127>;


Hmm, no phi node at bb 13 for _46 ....