[Bug middle-end/24851] [4.1 Regression] f2c miscompilation

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2005-11-14 16:27 -------
Valid testcase (?):

void abort(void);
int main()
{
  int a[10], *p, *q;
  q = &a[1];
  p = &q[-1];
  if (p >= &a[9])
    abort ();
  return 0;
}

fold_stmt is doing the &a[0] + -4B to &a[1073741823] transformation.  But it
somehow looks the C representation of &a[X] with pointer addition is not a
good idea.  The C++ frontend makes out of the above

int main() ()
{
  int a[10];

<bb 0>:
  if (&a[9] <= &a[1073741824]) goto <L0>; else goto <L1>;

<L0>:;
  abort ();

<L1>:;
  return 0;

}

I'm unsure how to fix this without completely disabling the comparison
folding for anything but == and !=.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24851