From:	mdruiter AT cs DOT vu DOT nl (Ruiter de M)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Question about optimization of DJGPP
Date:	22 Apr 1998 12:36:24 GMT
Organization:	Fac. Wiskunde & Informatica, VU, Amsterdam
Lines:	20
Message-ID:	<6hko88$bea$1@star.cs.vu.nl>
References:	<199804130936 DOT LAA13390 AT euronet DOT nl> <01bd68a5$c8e3b260$151601bf AT cb001687>
NNTP-Posting-Host:	sloep111.cs.vu.nl
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

> > I've made a little program and when I looked in the disassembler
> > window while running the program, I saw movl %eax,%eax. Why is
> > this instruction there? Did I forget to turn on optimization
> > somewhere?

Be sure to use -O or -O2 on the command-line. But I don't think
that's the problem. Could be because the compiler tries to align
jump-labels at 4 (or 8) byte boundaries for speed. Maybe the movl
%eax,%eax is faster than two nop's?

> Uhm.. It's because the compiler is like stupid and stuff..

No it's not. GCC is (at least one of) the best optimizing portable
compiler around.

-- 
Groeten, Michel.        http://www.cs.vu.nl/~mdruiter
  ____________
  \  /====\  /          "You know, Beavis, you need things that suck,
   \/      \/           to have things that are cool", Butt-Head.

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