Nieminen Mika <war### [at] cctutfi> wrote:

>Roland Mas <rol### [at] casimirrezelenstfr> wrote:
>: No.  At least with dece^H^H^H^Hrecent compilers, the generated code is
>: as fast as (if not faster than) the one done by hand.
>
>  This is and isn't true.
>  This isn't true, because compilers are not magic programs which can
>make asm-code impossible to make by humans. The compilers are made by
>humans and the optimizations made by compilers are coded by humans. So
>compilers can't do anything a human couldn't do.

In a perfect world, this would be true.

However, the fact is that there are a number of specific optimisation
strategies available for Pentium-class processors (particularly P2 and better)
that are the subject of NDA's from Intel. They are also very hard to achieve by
hand, even if you knew what they were (they involve, I believe, things such as
pipeline scheduling, arrangement of instructions to suit the way the CPU
prefetches, etc).

Needless to say, the big compiler vendors have access to this information. We
don't.

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