On Wed, 21 Sep 2005 04:10:47 +0200, Thomas Berg wrote:
>Have anyone used the long-displacement facility instructions
>(as in consistently do so to reduce base register usage) ?
>Are there any pitfalls or limitations that a relatively
>inexperienced programmer should be aware of ?
>Btw, why is there no "MVCY" instruction ? Is it because of
>the existence of the MVCL instruction or .. ?
Not consistently yet, no. (There were a few gaps - at least until the new
PoP & z9 offered more toys to play with.) What I have used seemed to all
work as advertised.
Don't feel bad about MVCY being missing; Ed is still holding a torch for
EXR (relative execute) and I'm kind of hoping for EXRG as a register-only
Execute Grande (EXR R1,R2 with R1 & R2 being 64-bit registers so that
every bit that's on ('1'b) in R1 gets OR-ed over the first (up to) 64-bits
at the R2 target instruction address (in millicode workspace or
similar)). I see that as the ultimate execute. (Motto: "64-bits while
you wait!") They could make it up to 64-bits depending on the opcode or
they could just say 'caveat emptor' at let you swing away at it. (I'm all
for the second choice myself.)
(Someone should warn the architects not to be drinking hot liquids while
they read this post.)
--
Tom Schmidt
Madison, WI
(Maybe it would be more like 'caveat empty'?)
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