Re: Quality of VAX compilers

=?ISO-8859-1?Q?Jan_Vorbr=FCggen?= <jvorbrueggen@mediasec.de>
12 Jun 2006 23:50:59 -0400

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From: =?ISO-8859-1?Q?Jan_Vorbr=FCggen?= <jvorbrueggen@mediasec.de>
Newsgroups: comp.compilers
Date: 12 Jun 2006 23:50:59 -0400
Organization: MediaSec Technologies GmbH
References: 06-06-009 06-06-027 06-06-034
Keywords: history, translator

>>The VAX hardware and VMS Operating System were designed together and
>>were a beautiful system. Digital Equipment Corporation (DEC) did a
>>good job transitioning to Alpha and OpenVMS.
> I think you will get some argument on that, the Alpha instruction set
> left a lot to be desired, which is one reason a lot of the VAX objecrs
> were 'VEST'ed


Really? AFAICT, the three main reasons for VESTing (binary translation
with run-time support) were


- no source available (hah! so what else is new?)
- the relevant compiler was not ported to Alpha (e.g., SCAN)
- performance was good enough for the translated code, why bother with
      re-everythinging it?


Code heavily using the "commercial" instruction set suffered, but it
was already suffering on the later VAX implementations. Sometimes the
compiler upgrade helped - for instance, certain COBOL data types were
implemented as BCD on VAX but changed to use native 64-bit integers on
Alpha. VESTing such applications could only have made things worse.


Jan


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