Path: utzoo!utgpu!water!watmath!clyde!att!ucbvax!decwrl!labrea!Portia!mouser
From: mouser@Portia.Stanford.EDU (Michael Wang)
Newsgroups: comp.sys.mac
Subject: Benchmarking C Compilers (was Re: LightspeedC 3.0 Review (long))
Keywords: Lightspeed C, gcc, Dhrystones
Message-ID: <3133@Portia.Stanford.EDU>
Date: 21 Jul 88 09:29:53 GMT
References: <76000259@p.cs.uiuc.edu> <4990@husc6.harvard.edu>
Reply-To: mouser@portia.stanford.edu (Michael Wang)
Organization: Stanford University
Lines: 46

In article <76000259@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
> Recently, Comp.arch listed the results of a Dhrystone test of
> different C compilers.  The results included LightspeedC, at 2467
> Dhrystones, and also Sun 3/50's, at as much as 4000+ Dhrystones on a
> 16.67Mhz 68020 (gcc compiler).  So I don't think that LightspeedC is
> nearly as fast as possible.  A better compiler for the same CPU (at
> 1Mhz more clocks) runs almost 8/5 as fast!  Oh well, some day we will
> have extremely efficient compilers for the macintosh.... I hope.

Later, in article <4990@husc6.harvard.edu> singer@endor.harvard.edu
(Rich Siegel) writes:
>       I agree that LightspeedC isn't as efficient as possible,  but to
> compare itts execution on a Mac II to GCC's execution on a Sun 3 is unfair,
> since the two machines have fundamentally different hardware designs.
>
>        If you want to  make a valid comparison, run gcc on a Mac II running
> A/UX. There's more to a comparison than just saying "The sun 3 has the same
>CPU as the Mac II, and the same clockk speed (+/- 1MHz), but LightspeedC runs
> slower on the Mac II, so it must be inferior."
> 
>               --Rich

Well, if you believe vendor literature, the gcc compiler, developed by
Green Hills Software (not GNU CC), running on a Macintosh II under A/UX hits
6600 Dhrystones compared to 2950 Dhrystones for the standard cc under A/UX.

What this means, if you believe benchmarks, is either that the Macintosh II
version of the gcc compiler is much better than the Sun 3/50 version, or that
a Macintosh running A/UX is faster than a Sun 3/50 running BSD UNIX.  I tend
to believe the later case :-).

Unfortunately, on the purely Macintosh level, Lightspeed C, at 2500-2900
Dhrystones, has quite a way to go before it matches an established optimizing
compiler like gcc (sorry Rich).  Of course you can always argue that the
Mac OS is quite a bit different than A/UX.  On the more positive side,
Lightspeed C does do about as well as the standard AT&T cc compiler (which I
assume was running in its optimizing mode).

-Michael Wang

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