low level optimization

[Jim Giles]

>> And, as I said, if the standard says you _may_
>> do something, the implementation _must_ permit you to do it.
>
> If a compilation system waits until it knows where all the source code is
> to perform code generation, what is the user not being permitted to do?
> Get slow code?  No thanks!

If the compilation system waits until it knows where all the source
code is to perform code generation, it's got a long wait coming.  Many
vendors don't distribute source code.  Your compilation system is 
_never_ going to know where the vendor's source code is.  What you are
not permitting the user to do is one of the very things that separate
compilation is _for_ - vendor distribution of _object_ code.  If your
compiler/language requires source to get fast code, you should think
about changing languages.

J. Giles