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From: peter@sugar.UUCP (Peter da Silva)
Newsgroups: comp.sys.amiga
Subject: Re: Request for Compiler Info
Message-ID: <941@sugar.UUCP>
Date: Fri, 30-Oct-87 00:23:40 EST
Article-I.D.: sugar.941
Posted: Fri Oct 30 00:23:40 1987
Date-Received: Wed, 4-Nov-87 02:36:11 EST
References: <8710262044.AA08743@cory.Berkeley.EDU>
Organization: Sugar Land UNIX - Houston, TX
Lines: 29

In article <8710262044.AA08743@cory.Berkeley.EDU>, dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
> >Manx uses a bogus "memory model" scheme to avoid having to do a good
> >optimisation job. But even in their large model they're faster than Lattice.
> >I always use large model myself... if I wanted a segmented architecture
> >I would have gone with IBM. No smiley.
> 
> 	Not at all... you can think of it as:
> 
> 	small/large data:	do I want to use relative or absolute addresses
> 	small/large code:	do I want to use pc-rel or absolute addresses

If they can't do it without me having to take special precautions to make
my code compatible with the small models, I don't want to know about
it. Neither of these models work well on the Amiga, since they prevent scatter
loading. I'm sure it's largely a hangover from their IBM-PC compiler. After all,
in the older releases they even went to the trouble of mapping the nice Amiga
timestamp format into the gross IBM-PC format.

> 	relative addressing takes one word less than absolute addressing, thus
> 	causing a not-so-trivial speedup when accessing global/static 
> 	variables.  Referencing auto (stack) variables doesn't change since
> 	they are SP-relative anyway.  

So they should use relative addressing for data/code that they know to be local
to the module, but still use 32-bit pointers for indirection to maintain
compatibility. The programmer should not have to know about it.
-- 
-- Peter da Silva  `-_-'  ...!hoptoad!academ!uhnix1!sugar!peter
-- Disclaimer: These U aren't mere opinions... these are *values*.