Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!wuarchive!decwrl!ogicse!verdix!qtc!glass
From: glass@qtc.UUCP (David N. Glass)
Newsgroups: comp.arch
Subject: Re: Compilers vs. architecture
Message-ID: <2006@qtc.UUCP>
Date: 14 Feb 90 00:11:00 GMT
References: <8905@portia.Stanford.EDU>
Organization: Quantitative Technology Corp., Beaverton, OR
Lines: 38

> In article <19233@dartvax.Dartmouth.EDU> jskuskin@eleazar.dartmouth.edu (Jeffrey Kuskin) writes:
> 
> >Isn't one of the RISC folks' main arguments for simple instruction sets
> >that current compilers don't effectively exploit the complex addressing
> >modes and instructions supported in CISC chips?  Perhaps someone would
> >like to speculate on what progess the next decade will bring in
> >compiler technology...
> 

As processors contain more parallel functional units, compiler technology
is going to have to work harder in keeping all concurrent units as busy as
possible, given the application.  For this reason, software pipelining and
local/global compaction is becoming a very hot topic.

It's easy to see why when you look at some benchmarks we've produced with
our own set of code rescheduling products.  The tools are used as
an assembly language to assembly language translator between the compiler
and assembler steps.  Given current i860 compilers, for example, we have 
seen execution speed improvements of as much as 206% (livermore loop kernel 7) 
with an average of 51% over the entire livermore loop suite.  Our Intel 960CA
scheduler averages 21% execution improvement, with applications like matrix
multiply getting 104% speedup.  The 88000 version improves Linpack 40%,
and livermore loops up to 80% (livermore 1).

I see more work being done in the area of global or inter-basic block 
optimizations.  Things like software pipeling over multiple blocks,
or an outer loop that contains inner loop (or loops).  Further, more
analysis of data dependencies will happen, especially with relation
to managing memory heirarchies.

-- Dave Glass

+----------------------------------------------------------------------
|   David N. Glass                         ...ogcvax            
|   Quantitative Technology Corp.          ...verdix   !qtc!glass 
|   8700 SW Creekside, Suite D             ...sequent             
|   Beaverton, OR  97005
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