[Info-vax] i4 Possible?

John Reagan xyzzy1959 at gmail.com
Fri Feb 7 22:22:49 EST 2014


On Friday, February 7, 2014 5:41:25 PM UTC-5, JF Mezei wrote:

> I take it none of the compilers on VMS can generate code to take
> advantage of Poulson ? Or were they updated to allow this before HP put
> the axe on everything ?
> 

I don't know of any Poulson specific changes when I was last there.

There would be two areas:

1) Poulson has some new instructions that would help with integer multiply and division.  How much?  I don't know.  Never touched one.  But anything to avoid using the floating instructions (and the limited floating slots in the bundle types) would probably help.  Depends on how much of your application does integer multiplies and divides.  (Don't forget the compiler really tries to convert those into other operations - strength-reduction on array accesses can often eliminate the integer multiplies).

2) To use the additional resources on the chip (I think more adders, memory access units, etc), you want the compiler to try harder to find more parallelism and produce longer instruction groups.  That is hard to quantify.  For programs wouldn't benefit from it; others might.  Either way, more analysis would take more time.






More information about the Info-vax mailing list