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.

struct Foo;

Foo* foo()
{
    return null;
}

void main()
{
    Foo* f = foo();
    assert(f is null);
}