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Date:      Mon, 10 Mar 2003 23:17:49 +0000
From:      Mark Murray <mark@grondar.org>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        Peter Jeremy <peterjeremy@optushome.com.au>, chat@FreeBSD.ORG
Subject:   Re: cvs commit: src/lib/libc/i386/string Makefile.inc wcscmp.S 
Message-ID:  <200303102317.h2ANHnIg074715@grimreaper.grondar.org>
In-Reply-To: Your message of "Mon, 10 Mar 2003 14:54:47 PST." <3E6D17B7.5FDCEAFC@mindspring.com> 

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Terry Lambert writes:
> > I'm guessing that this means there will always be room for humans to
> > hand-code assembler. How far can this be made redundant, given that
> > there is still lots of effort going into hand-coded asm functions?
> 
> I think that in all cases where it's possible, you want to have
> C language equivalents.  Yeah, they are slow, but they are also
> portable.  It's really a pain to try to go to a new architecture
> when there's all this assembly language code lying around.  At the
> very least, you want there to be both platform independent and
> platform dependent versions of the code.

You are missing the point of my question.

I _know_ a guru will aways eke out a bit more performance. What I'm
asking is "what shape is the performance/effort curve for _compilers_?"
and I'm leading towards "When, if ever, will compiler optimization
be such that hand coding assembler for system libraries is a waste
of time (on average)?" What I _really_ want to know is how much
optimization is _not_ done, either because its too hard/slow, or
because its too difficult to do. I also want to know how complete
we think our optimization understanding is, ie whether there is
lots of scope for research or we think we know most of the theory
already.

M
--
Mark Murray
iumop ap!sdn w,I idlaH

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