linux-kernel - Re: Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3

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Message-ID: <45C9246F.9050300@zytor.com>
Date:	Tue, 06 Feb 2007 16:59:27 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Etienne Lorrain <etienne_lorrain@...oo.fr>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>, vgoyal@...ibm.com,
	linux-kernel@...r.kernel.org
Subject: Re: Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation
 for loading by Gujin 1/3

Etienne Lorrain wrote:
> H. Peter Anvin wrote:
>> I've long wished that someone would do a proper 16-bit x86 port of gcc; 
> 
>> however, the .code16gcc is usually good enough, although it produces 
>> code which is a lot bigger than it needs to be.
> 
>   It is only that much bigger if you compare to 16 bits integer compilers,
>  but once you deal with 32 bits integers in real mode you have one extra byte
>  out of the two - which is still better than dealing with dx:ax.
> 
>  Last time I compiled (long time ago) some piece of code with and without
>  .code16gcc it was approx 15% bigger - approx what you get when optimising.
> 

That's not a valid comparison, because you're using 32-bit registers to 
hold 16-bit pointers, and then sticking 67 prefixes on completely 
unnecessarily.

	-hpa
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