Lpc2000

> I was certainly used to fairly aggressive and neat opts with IAR, but I've
> never seen it change the sequence of things, that seems a bit rich.
> Mind you, that was on MSP430 and on AVR mainly.

I wouldn't expect the same kinds of optimizations on uCs that you may see
on larger systems.  IBMs xcc for the POWER arch does a lot of bizarre
stuff to code.  If the compiler can tell what the inputs of a function
are and all the things it touches, then if this does not conflict with
other things happening in the code, there is no programmer visible
problem with the compiler moving the execution of that chunk of code
around.  There are even compilers that will throw it off in another
thread automatically--should you have multiple CPUs, this can be a win.

> Now that I know these things can happen (moving code around), I know what to
> look for and can stop bugging you guys :-)
> Without knowing this things look daunting.
> 
> Is there a specific include file to use barrier() ???

It may not even be called barrier on your system.  It's a compiler
specific option, so I don't even know where to point you.  Sorry.

Cheers,
David