Why is Clang optimizing this code out?

Here’s a simpler test case which points out that it’s a compiler bug:

http://coliru.stacked-crooked.com/a/58b3f9b4edd8e373

#include <cstdint>

int main()
{
    uint32_t i = 0;
    uint32_t count = 1;

    while (1)
    {
        if( i < 5 )
            count+=1;

        if (i == 0xFFFFFFFF)
            break;
        i++;
    }

    return count; // should return 6
}

The assembly shows that it outputs 1, instead of 6. It doesn’t think it’s an infinite loop either, in which case the assembly doesn’t return from main.