Path: utzoo!utgpu!watmath!julian!uwovax!7103_300
From: 7103_300@uwovax.uwo.ca (Eric Smith)
Newsgroups: comp.sys.atari.st
Subject: Re: Comment on PD/Shareware C compiler
Message-ID: <2171@uwovax.uwo.ca>
Date: 8 May 89 09:11:51 GMT
References: <1048@orbit.UUCP> <1471@atari.UUCP> <703@forty2.UUCP> <539@TSfR.UUCP>
Lines: 49
Organisation: University of Western Ontario, Canada

In article <539@TSfR.UUCP>, usenet@TSfR.UUCP (usenet) writes:
> In article <703@forty2.UUCP> poole@forty2.UUCP (Simon Poole) writes:
>>In article <1471@atari.UUCP> apratt@atari.UUCP (Allan Pratt) writes:
>>> [Discussion of lousy Dhrystones for GCC]
>>>                                              .....It is beaten by ALL
>>>the other Atari C compilers I could find (Dhrystone 2.1), by a factor of
>>>two or more in some cases.  This includes using -O, but no other
>>>optimization options; some may pay, others aren't available (like
>>>"no-function-cse") ...
>> 	[discussion of problems with benchmarking deleted ] 
>   If the Dhrystone was completely invalid, it wouldn't be used.  10-15%
> variance can probably be ignored, but when a compiler turns in results
> that are half of the other compilers, it's probably an indication that
> something is badly damaged in that compiler.

Here are my benchmark results for the GCC v1.31, Sozobon, and Laser C v1.01.
Several things to keep in mind (besides, of course, the generic problems
with benchmarks):
(1) Both Laser and the GCC have newer versions available (1.35 and 2.0
respectively).
(2) I used Dhrystone 1.1, NOT 2.1 , so these results are not directly
comparable to the ones posted by Mr. Pratt. They should give an indication
that the GCC does indeed generate good code, though.
(3) I don't know why GCC 1.23 supposedly generated such poor code. I do
know that its library had a few bugs; sometimes a buggy time() routine can
do strange things to timing routines :-).

In the table below, all compilations are done with the -O flag, where
available. The GCC has several extra levels of optimization available which
were *not* used.

Benchmark results:
Compiler		Dhrystones/sec
Laser 1.01		818
Laser w. regs.		849
GCC 1.31		979
GCC w. regs.		979	(<- the GCC optimizer knows how to use regs.)
Sozobon	1.0		932
Sozobon w. regs		978

One final note: Laser and Sozobon were using 16 bit int's; GCC uses 32 bit
int's. Newer versions of the GCC also support 16 bit int's (actually 1.31
did as well, but the library didn't have any 16 bit routines).
--
Eric R. Smith                      email:
Dept. of Mathematics               7103_300@uwovax.uwo.ca
University of Western Ontario      7103_300@uwovax.bitnet
London, Ont. Canada N6A 5B7    (a shared mailbox: put my name on
ph: (519) 661-3638              the Subj: line, please!)