Subject: Re: VAX instructions (Was: VAX VECTOR chip, what part number?)
To: Anders Magnusson <ragge@ludd.luth.se>
From: David Brownlee <abs@netbsd.org>
List: port-vax
Date: 05/23/2001 11:08:00
On Wed, 23 May 2001, Anders Magnusson wrote:
> insque/remque are used to manipulate the process queues, yes.
> scanc/skpc are used by the ffs code.
> movc3/movc5/locc are used for memcpy/memset/strlen (bcopy/bzero/...)
> ffs is just ffs(3).
>
> libc only uses a few of them because there are VAXen that do not have
> them in hardware that gets extremely slow if those isns's are used...
Are there any compile time options to control the use of them?
I can't see anything in the gcc info page. Would it make sense
to add any so those with more 'instruction rich' CPUs could
elect to recompile to gain more speed, something akin to -mcpu=v8
on a sparc box. Hmmm, presumably that could also be useful if
the cost of scheduling instructions varies between different
vaxes. At the evry last it could be set automatically in kernel
compiles when targeting specific vax models.
--
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