Re: [avr-chat] Missed Optimisation ?

[Graham Davies]

Colin O'Flynn wrote:

> Perhaps if the issue comes up again, referring to the ANSI C spec might at
> least have some authority?

For those that understand the terminology, yes.

> ... any expression referring to such an object [with volatile-qualified
> type] shall be evaluated strictly according to the rules of the abstract
> machine...

Not everyone will understand what this means.  I have tried to provide an
interpretation of this in the context of bob's original post.

> (114): A volatile declaration may be used to describe an object
> corresponding to a memory-mapped input/output port ...

This is actually advice for how to use the volatile storage qualifier and
probably got into the specification due to just the confusion we're
experiencing now.

> Which again sounds exactly as GCC behaved.

YES!

Graham.