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From: jim@jagmac2.gsfc.nasa.gov (Jim Jagielski)
Newsgroups: comp.compilers
Subject: Unisoft C Compiler for A/UX -- dhrystone and -O
Keywords: code, C, analysis, benchmarks
Message-ID: <2707@dftsrv.gsfc.nasa.gov>
Date: 6 Jul 90 14:06:00 GMT
Sender: compilers-sender@esegue.segue.boston.ma.us
Reply-To: jim@jagmac2.gsfc.nasa.gov (Jim Jagielski)
Distribution: na
Organization: NASA Goddard Space Flight Center
Lines: 21
Approved: compilers@esegue.segue.boston.ma.us

I have Unisoft's Optimizing C Compiler for A/UX (gcc -- NOT gnu cc) and
have noticed something strange.

When compiling the dhrystone benchmark, I get faster performance from the
non-optimized binary as compared to the optimized version. The difference
is small (~12000 vs ~11700, with maximum of ~12444 without opt. and a
min of ~11500 with opt.) but there. Doing other benchmarks, esp. with
floats and doubles, performance is expected (i.e., -O results in quicker
code, but a little bigger) but this discrepency in dhrystones is
interesting...

Anyone else have any experience with Unisoft or a similar occurance?
--
           Jim Jagielski                    NASA/GSFC, Code 711.1
     jim@jagmac2.gsfc.nasa.gov               Greenbelt, MD 20771
[Given that the instructions for Dhrystone tell you not to use a global
optimizer, I wouldn't rule out the possibility that this is yet another
compiler tweaked to make Dhrystone run fast. -John]
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