[Bug tree-optimization/69336] Constant value not detected

[ktkachov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69336

ktkachov at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 CC|                            |ktkachov at gcc dot gnu.org

--- Comment #9 from ktkachov at gcc dot gnu.org ---
(In reply to Richard Biener from comment #6)

> 
>       * g++.dg/tree-ssa/pr69336.C: New testcase.

This testcase fails for me on arm-none-eabi.
The optimized dump on -std=c++14 -O3 -fdump-tree-optimized -std=c++14 contains:
int main() ()
{
  size_t n;
  const struct static_map cmap;
  const char * _4;
  int _5;
  int _11;
  void * _15;
  int _25;

  <bb 2>:
  cmap = *.LC3;
  _5 = cmap._values[0].second.first;
  if (_5 == 8)
    goto <bb 5>;
  else
    goto <bb 3>;

  <bb 3>:
  _25 = cmap._values[1].second.first;
  if (_25 == 8)
    goto <bb 5>;
  else
    goto <bb 4>;

  <bb 4>:
  _11 = cmap._values[2].second.first;
  if (_11 == 8)
    goto <bb 5>;
  else
    goto <bb 6>;

  <bb 5>:
  # n_8 = PHI <2(4), 0(2), 1(3)>
  _4 = MEM[(const char * const &)&cmap]._values[n_8].second.second;
  if (_4 == 0B)
    goto <bb 9>;
  else
    goto <bb 10>;

  <bb 6>:
  _15 = __cxa_allocate_exception (8);
  std::out_of_range::out_of_range (_15, "Key not found");

  <bb 7>:
  __cxa_throw (_15, &_ZTISt12out_of_range, __comp_dtor );

<L6>:
  __cxa_free_exception (_15);
  __builtin_cxa_end_cleanup ();

  <bb 9>:
  abort ();

  <bb 10>:
  cmap ={v} {CLOBBER};
  return 0;

}