Messages in this thread | | | Date | Wed, 14 Aug 2002 00:22:43 +0200 (CEST) | From | Adrian Bunk <> | Subject | Re: [patch 4/21] fix ARCH_HAS_PREFETCH |
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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
--
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