[4.7 Regression] Wrong optimization with -O2

[Muhammad Annaqeeb]

As reported by Mike Mirzayanov on GCC Bugzilla:
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60766 and http://codeforces.com/blog/entry/11450
Ubuntu 14.04 includes GCC 4.8.2 which is affected with bug.
Please upgrade to GCC 4.8.3 or later in which the bug is fixed.
"
Compile with -O2 and input 9

Compile the following code with -O2:

~~~~~
#include <cstdlib>
#include <iostream>
#include <cstdio>

using namespace std;

int main() {
    int n;
    cin >> n;

    for (int x = 0; x <= n; x++) {
        if (n == x + (x + 1) + (x + 2)) {
            cout << x + 2 << " " << x + 1 << " " << x << endl;
            exit(0);
        }
    }
    cout << -1 << endl;
    return 0;
}
~~~~~

Start binary and enter 9

It will print "-1", but expected output is "4 3 2".
"

[Matthias Klose (doko)]

this is fixed in trusty-updates