Something about IR Optimization

In other words, I first need to decide where this bug really belongs – in the optimizer, the code generator, or even the IR structure itself. Thus, there really isn’t a ‘first’ reference to a value, before the code generator introduces the concept. But it also means that the property we’re interested in – a value is computed before it is used in, in all possible code flow paths – isn’t really expressible by the IR.

Source: brrt-to-the-future.blogspot.com