[Bug tree-optimization/21568] [4.0/4.1 regression] Casts in folding *& omitted

["gcc2eran at tromer dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From gcc2eran at tromer dot org  2005-07-03 04:55 -------
Why was this bug closed? The testcases in comment 5 do *not* pass.

Here's the first testcase, fixed to compile cleanly:

----------------
int avail;

int main() {
  volatile int **outside = (volatile int**)0x0123;
  *outside = &avail; 
  // avail is now potentially modifiable externally to the program
  while (*(volatile int *)&avail == 0)
    continue;
  return 0;
}
----------------

Following the reasoning of comment 5, the read in the loop must not be optimized
away. Still, gcc 4.0.0 with -O3 produces this:

----------------
...
        movl    $avail, 291
        movl    avail, %eax
        testl   %eax, %eax
        je      .L5
        xorl    %eax, %eax
        leave
        ret
.L5:
        jmp     .L5
----------------

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21568