Path: utzoo!utgpu!attcan!uunet!munnari!jkjl
From: jkjl@munnari.oz (John Lim)
Newsgroups: comp.arch
Subject: Re: register save/restore
Message-ID: <2557@munnari.oz>
Date: 3 Nov 88 05:56:35 GMT
References: <3300037@m.cs.uiuc.edu> <5938@killer.DALLAS.TX.US> <7580@aw.sei.cmu.edu>
Reply-To: jkjl@munnari.UUCP (John Lim)
Organization: Comp Sci, Melbourne Uni, Australia
Lines: 21

One issue about the caller/callee saves argument that hasnt been brought
up is code size. Callee saves minimizes code size. For example in C :

	a() {} 
	b() {}
	c() {}
	f() {a();b();c();}
	g() {b();a();c();}

If caller saves, assuming that saves and restores take 1 instruction each,
we get 12 save/restore instructions used for the above code. If callee saves,
we get 6 save/restore instructions needed only.

Not too important you might think, but i remember that M'soft used the pascal
calling convention in Windows to save 5% (if i remember) of code, which is
similar in principle to the caller/callee argument.

Luckily, this isn't so much of an issue when you arent confined to 640K
of mem...
	
	john lim