[Bug c++/86216] g++ ICE on valid code: verify_ssa failed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86216

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
I can't fully reproduce the obfuscation of the C++ FE (the +-1) but the
following is close but it also works:

typedef int intptr_t;
void foo (intptr_t n, unsigned a)
{
  typedef intptr_t ArrTy[(long)a+1];
  ArrTy buffer2;
  ArrTy buffer1[(long)a+1];
  void bar ()
    {
      n = sizeof(buffer1[n]);
      void baz()
        {
          n = sizeof(buffer2);
        }
      baz();
    }
  bar();
}

and it has similar gimplification (but not broken):

foo (intptr_t n, unsigned int a)
{
...
      _1 = (long int) a;
      D.1910 = _1 + 1;

bar ()
{
  static void baz ();

  _1 = (unsigned int) D.1910;
  _2 = _1 * 4;
  n = (intptr_t) _2;
  baz ();
}

baz ()
{
  _1 = (unsigned int) D.1910;
  _2 = _1 * 4;
  n = (intptr_t) _2;
}

without the array size adjustment I get the SAVE_EXPR only wrapping a, so some
promotion done by the C++ FE ends up breaking things.