ANSII C, optimization, and "hardware registers"

[Henry Spencer]

> [Compiler is optimizing out a wait-for-hardware-done loop.]
> ...
> 1.  Was this legal code generation?
> 2.  Note that this compiler did "simple" optimizations as part of the code
> 	generation. Is this legal?

As to whether it's legal by K&R, the only answer is "mumble".  This
thorny issue was never addressed in the old days.  The draft ANSI standard
has a "volatile" declaration that you can use to tell the compiler "don't
get tricky with this variable, it may change underfoot".
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry