Re: Folk Theorem: Assemblers are superior to Compilers

winikoff@munta.cs.mu.OZ.AU (Michael David WINIKOFF) writes:
>>... Didn't Ritchie [say it]
>>accounted for a 10% loss when the Unix kernel was rewritten in C?
>Unix rewritten in C --- this was on a CISC processor.


Bear in mind, also, that this was with a relatively simple compiler. It
put a fair bit of effort into good local code generation, but made not the
slightest attempt at global optimization. Note that when I say "local", I
really mean "local" -- for example, the reason why C has a "register"
keyword for declarations is that the compiler made no attempt to do clever
register allocation.


Actually, I don't recall having seen Dennis quote a specific number like
"10%". It's hard to compare the assembler and C versions of Unix, because
the re-coding in C involved extensive internal redesign, not just
translation. The original Ritchie&Thompson paper quotes a code growth of
about one-third, but notes that the new system had many functional
improvements as well.
--
enry Spencer @ U of Toronto Zoology, henry@zoo.toronto.edu utzoo!henry
--

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