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From: preston@ariel.rice.edu (Preston Briggs)
Newsgroups: comp.arch
Subject: Re: What is the ratio of programs sizes CISC versus RISC
Message-ID: <1991Jun13.173625.24315@rice.edu>
Date: 13 Jun 91 17:36:25 GMT
References: <pb.676737175@atperf.idca.tds.philips.nl> <3429@crdos1.crd.ge.COM>
Sender: news@rice.edu (News)
Organization: Rice University, Houston
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pb@idca.tds.philips.nl (Peter Brouwer) writes:
>| Who can give me some information about the ratio of program sizes of RISC
>| versus CISC. Code size (text) and total executable file size, both 32
>bit systems, both unix flavors.

davidsen@crdos1.crd.ge.com (bill davidsen) writes:
>Several files compiled in Xenix/386 (SCO C), Sun4 (Sun C), and MIPS
>(Ultrix C). All use -O.
...
>Draw any conclusions you want, I've never seen a program which wasn't
>15-25% larger in RISC, but that doesn't seem to a good reason for
>choosing a machine.

I don't much like this sort of comparison.
Compilers behave too differently for executable sizes to be
of architectural significance.  For example, the MIPS and Sparc
compilers do loop-unrolling.  The RS/6000 compilers don't.
I don't know about particular 386 compilers.

More interesting is path-length comparisons (number of instructions
actually executed).  Pixie (and pixie-clones) can get these numbers.
If they'll tell you the average instruction length for the CISC
machines, then you could find something interesting
(like number of bytes of instruction fetched).

Of course, I'd really prefer to count delays caused by I-cache misses.

Preston Briggs