[Bug c/19056] New: 4.0 optimizes away a SEGV; 3.4.1 does not

[bh at techhouse dot brown dot edu]

A minimized test case:

int main() {
    int y = 1;
    int *x = &y;
    volatile int sum = 0;
    while(1) {
        sum += *x;
        x++;
    }
    return 0;
}

Clearly, this should crash; under 3.4.1 it does.  Under my checkout of a few
hours ago, however, it does not: instead, it enters an infinite loop (everything
inside the while(1) gets optimized away and we're left with just a jmp).

Workaround: make either x or sum volatile.  This forces it to actually do the
computations inside the loop.

I'm not sure whether to view this as a compiler bug: this code is, at heart,
morally unbalanced.  But it is a change in behaviour so I figured I'd report it.

-- 
           Summary: 4.0 optimizes away a SEGV; 3.4.1 does not
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bh at techhouse dot brown dot edu
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19056