Now that we're using LLVM 2.5, we can stop always running the CFGSimplification pass. The pass was originally added as a workaround for a LLVM 2.4 bug where debug info would reference labels that have been optimized away.

module c;

void main()
{
    ushort a = 0xFFF0;
    ushort b = 0x0FFF;
    auto t = a & b;
    a &= b;
    assert(t == a);
}