Re: [avr-chat] Missed Optimisation ?

[Graham Davies]

Michael Hennebry wrote:

> > [this bit is me writing] ...  When debugging a program, I like to be
> > able to follow along the logic I expressed in the source code, so
> > I would not be happy if it had changed beyond all recognition ...

> This is an argument against optimization generally,
> not specifically the kind under discussion.

No, it isn't.  It's an argument only against optimization that prevents me 
from "... follow[ing] along the logic I expressed in the source code" and 
that "change[s the program flow] beyond all recognition".  I think in your 
eagerness to disagree with me you are ignoring what I actually write.

> ... the as-if rule applies even to volatiles when the
> compiler has enough information to use it.

No, it doesn't, for reasons that have been adequately explained, mainly 
conformance to the standard.

> Except for atomicity, the semantics are the same ...

The C language is unaware of atomicity.  The semantics are different in the 
presence of read side-effects.

Graham.