Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!gatech!purdue!mentor.cc.purdue.edu!l.cc.purdue.edu!cik
From: cik@l.cc.purdue.edu (Herman Rubin)
Newsgroups: comp.arch
Subject: Re: delayed branch
Summary: I have often wanted to do so
Message-ID: <1462@l.cc.purdue.edu>
Date: 1 Aug 89 11:40:42 GMT
References: <2246@taux01.UUCP>
Organization: Purdue University Statistics Department
Lines: 17

In article <2246@taux01.UUCP>, cdddta@tasu76.UUCP (David Deitcher) writes:
> "Delayed branch" is a technique used by RISC machines to make use of the
> extra cycle needed to calculate branch targets. The compiler will put
> an instruction after the branch to be executed by the CPU while the
> branch target is being calculated. Does anyone have information as to
> how often the compiler is able to put a useful instruction after the
> branch as opposed to filling it with a NOP?

This has nothing to do with the capabilities of the compiler, but I have
often wanted to put one, or even several, instructions between a branch
instruction and its execution.  As most problems have a substantial amount
of order independence of operations, I would be surprised if a useful
instruction could not be inserted in well over 90% of the cases.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP)