On 13 Aug 2002, H. Peter Anvin wrote:
>...
> > > Because the compiler sees:
> > >
> > > for (i = 0; i < N; i++)
> > > ;
> > >
> > > and it says "ah ha. A busy wait delay loop" and leaves it alone.
> > >
> > > It's actually a special-case inside the compiler to not optimise
> > > away such constructs.
> >
> > Why is this a special case? As long as a compiler can't prove that the
> > computed value of i isn't used later it mustn't optimize it away.
>
> Bullsh*t. It can legitimately transform it into:
>
> i = N;
>...
Ah, my misunderstanding:
"optimize away" didn't mean "completely remove it" but "transform it to
something semantically equivalent".
> -hpa
Thanks
Adrian
--You only think this is a free country. Like the US the UK spends a lot of time explaining its a free country because its a police state. Alan Cox
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This archive was generated by hypermail 2b29 : Thu Aug 15 2002 - 22:00:34 EST