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From: grunwald@uiucdcsm.cs.uiuc.edu
Newsgroups: comp.lang.c++
Subject: Re: Another Performance Comparison
Message-ID: <4800023@uiucdcsm>
Date: 17 May 88 06:10:00 GMT
References: <4800022@uiucdcsm>
Lines: 23
Nf-ID: #R:uiucdcsm:4800022:uiucdcsm:4800023:000:819
Nf-From: uiucdcsm.cs.uiuc.edu!grunwald    May 17 01:10:00 1988


Here's some more figures on that simulation program.

All of these programs were compiled using G++ V 1.21.1. The only difference
is the command line options

	Options						Time (seconds)
----------------------------------------------------------------------------
(i)   -O							579
(ii)  -O -finline-functions					554
(iii) -O -finline-functions -fomit-frame-pointer		546
(iv)  -O -finline-functions -fomit-frame-pointer -fcombine-regs	569

So, if you've got production code which you don't intend to debug, G++
using (iii) looks like a good deal. Perhaps the difference between G++
and C++ is that C++ tends to auto inline more functions?

It's curious that combine-regs slows things down. That would take some
playing around to determine that the problem is.

Dirk Grunwald
Univ. of Illinois
grunwald@m.cs.uiuc.edu