------- 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
