Bug#696205: g++-4.4: for condition fails with -O2

[Chris Frey <cdfrey@foursquare.net>]

Package: g++-4.4
Version: 4.4.5-8
Severity: normal

When compiling the following simple program:

#include <iostream>
using namespace std;

int main()
{
	for( int a = 0, b = 1; a >= 0 && b >= 0 ; ) {
		cout << a << ", ";
		int sum = a + b;
		a = b;
		b = sum;
	}
}

If I use:

g++-4.4 -Wall -O2 -o fib fib.cc

Then the output doesn't stop when the value of a wraps into negative
territory.

If I use:

g++-4.4 -Wall -O0 -o fib fib.cc

Then it does stop, as expected.

- Chris


-- System Information:
Debian Release: 6.0.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 3.4.23 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash

Versions of packages g++-4.4 depends on:
ii  gcc-4.4                   4.4.5-8        The GNU C compiler
ii  gcc-4.4-base              4.4.5-8        The GNU Compiler Collection (base 
ii  libc6                     2.11.3-4       Embedded GNU C Library: Shared lib
ii  libgmp3c2                 2:4.3.2+dfsg-1 Multiprecision arithmetic library
ii  libmpfr4                  3.0.0-2        multiple precision floating-point 
ii  libstdc++6-4.4-dev        4.4.5-8        The GNU Standard C++ Library v3 (d

g++-4.4 recommends no packages.

Versions of packages g++-4.4 suggests:
pn  g++-4.4-multilib             <none>      (no description available)
ii  gcc-4.4-doc                  4.4.4.nf1-1 documentation for the GNU compiler
pn  libstdc++6-4.4-dbg           <none>      (no description available)

-- no debconf information