Xref: news2.mv.net comp.os.msdos.djgpp:2103
From: fnunez AT cs DOT uct DOT ac DOT za (Fabian Nunez)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Optimization causes error?
Date: 23 Mar 1996 09:54:54 GMT
Organization: University of Cape Town
Lines: 36
Message-ID: <4j0hpe$er2@groa.uct.ac.za>
References: <31531424 DOT 2096 AT jeffnet DOT org>
NNTP-Posting-Host: dione.cs.uct.ac.za
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

In <31531424 DOT 2096 AT jeffnet DOT org> Chris Dial <cdial AT jeffnet DOT org> writes:

>I have a problem with DJGPP 2.0. When I turn all optimizations on it 
>gives me the following error at compile time:

>c:/djgpp/tmp\cciaaaaa: Assembler messages:
>c:/djgpp/tmp\cciaaaaa:697: Fatal error:Symbol MyLoop already defined.

>It does _not_ give me these messages if I only use partial optimization 
>or none at all (eg: -O3 causes the error, -O2 does not)

>asm(
>" MyLoop:
>  decl %ecx
>  jnz MyLoop"
>);  


This happens because the -O3 option goes berserk, inlining everything
it can. Unfortunately the inline asm does not touch the labels you
provide, so if you call your asm routine more than once in your code
there is more than one copy of your asm routine in the asm file generated
(compile with -S to see it). The solution is to simply write your asm
function in a different source file to the one it is used in (maybe 
asmstuff.cc). In this way the compiler cannot inline your asm (since it 
ends up in a different .o file) and your problem is solved.

(maybe this should be in the FAQ, it's kindof an annoying feature of GCC)

>-Chris Dial

--
Fabian Nunez, Bsc(hons) student, University of Cape Town                     
email:fnunez AT cs DOT uct DOT ac DOT za   web:http//www.cs.uct.ac.za/~fnunez
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