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From: lodman@ncr-sd.UUCP
Newsgroups: comp.arch
Subject: Re: Optimizing compiler's view on: no. of regs, aliasing, caller/callee save etc.
Message-ID: <1379@ncr-sd.SanDiego.NCR.COM>
Date: Mon, 23-Feb-87 11:57:20 EST
Article-I.D.: ncr-sd.1379
Posted: Mon Feb 23 11:57:20 1987
Date-Received: Thu, 26-Feb-87 19:00:45 EST
References: <902@orcisi.UUCP> <1283@ucbcad.berkeley.edu>
Reply-To: lodman@ncr-sd.UUCP (0000-Mike Lodman)
Organization: NCR Corporation, Rancho Bernardo
Lines: 18

In article <1283@ucbcad.berkeley.edu> faustus@ucbcad.berkeley.edu (Wayne A. Christopher) writes:
>WRT the discussion about whether the caller or the callee should save
>registers -- wouldn't the most efficient strategy be for the caller to
>pass the callee a mask of which registers are currently in use (by
>itself and previous functions)?  That way, the callee could AND its
>mask with the caller's mask and save those registers, and OR its mask
>and the caller's and pass that to any functions that it calls.  I think
>this should prevent any unnecessary saving of registers.

Wouldn't this force the linker to insert code to save and restore 
registers? It doesn't sound like a workable solution.



-- 
Michael Lodman
mike.lodman@SanDiego.NCR.COM 
{sdcsvax,cbatt,dcdwest,nosc.ARPA,ihnp4}!ncr-sd!lodman