On Fri, 22 Oct 2004, John Stiles wrote:
> If you're on a two's-complement CPU (i.e. any modern computer) and you
> use a reasonably modern compiler, you have nothing to fear...
> right-shift will sign-extend. The C standard doesn't require it because
> when the standard was written, there were still some one's-complement
> CPUs in existence.
>
I want people to be aware of the issue, rather than just be lucky with the
correctness of their code. When autovectorization in GCC arrives, some of
the C language vagaries might have to be revived to give the compiler more
freedom to actually vectorize code.
That being said, I also write most code with the assumption that I am on a
32 bit two's complement machine. It would be hard to tune code if nothing
could be taken for granted about the hardware.
Holger
P.S.: You and your Blizzard buddies are more than welcome to ask for
optimization hints! Anything I can do to help you will only improve
the gaming experience on my aging 800MHz Powerbook. :-)
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