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From: tim@amdcad.AMD.COM (Tim Olson)
Newsgroups: comp.arch
Subject: Re: The 360 was a design landmark  (360 vs vax)
Message-ID: <18093@amdcad.AMD.COM>
Date: Wed, 26-Aug-87 22:07:59 EDT
Article-I.D.: amdcad.18093
Posted: Wed Aug 26 22:07:59 1987
Date-Received: Sat, 29-Aug-87 05:24:03 EDT
References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> <916@haddock.ISC.COM> <2596@ames.arpa>
Organization: Advanced Micro Devices, Inc., Sunnyvale, Ca.
Lines: 48

In article <2596@ames.arpa>, lamaster@pioneer.arpa (Hugh LaMaster) writes:
+-----
| In article <18088@amdcad.AMD.COM> tim@amdcad.UUCP (Tim Olson) writes:
| 
| >If the VAX instruction-set was designed for "maximum code density", they
| >certainly did a poor job.  Many processors (including some "RISCs" --
| >IBM ROMP and CRISP) can routinely beat it in code density.
| 
| Well, it was designed for high code density at the time. Two points:
| 1)  Maybe people have learned something in 10 years, and
| 2)  Be careful to compare oranges and oranges.  I think the code density
| produced by the VMS compilers is quite good, and compares favorably with
| code produced on other 32 bit architectures with good compilers.  It is
| a different test to compare the code produced by pcc, for example.  What
| comparisons were you referring to?
+-----

Whoops -- I may have spoken too strongly, here.  I was going on past
experience with our IBM RT-PC (ROMP processor) and our VAX 11/780,
comparing optimized object code.  Since the RT has a much better
optimizer, this would be an "unfair" comparison.  I just ran
(unoptimized) pcc on our internal assembler source, I got the following
text sizes for the object code files:

Module		Vax 11/780	RT-PC	       % change
condasm o	1060		1384		30 
eval o		3988		4268		7 
float.o		1716		1996		16 
lex.o		6120		6972		13 
macros.o	5036		5480		8 
odump.o		2272		2440		7 
opcodes.o	208		280		34 
pass1.o		604		736		21 
pass2.o		4720		7048		49 
procstr.o	6132		6028		-1 
pseudo.o	6304		6884		9 
seg.o		3172		2152		-32 
sipasm.o	1528		1320		-13 
sym.o		1388		1496		7 


So, overall, the VAX was more compact, although the RT was within 10% in
many cases, and was more compact in some.


	-- Tim Olson
	Advanced Micro Devices
	(tim@amdcad.amd.com)