On 5/28/2018 2:57 PM, Peter Relson wrote:
-- You might find that use of BAKR by the caller poses an unnecessary
dependency between the caller and the callee. Consider the alternative of
calling via BASR, and the callee deciding whether to save/restore regs via
BAKR/PR or via STMG(+STAM)/LMG(+LAM)
Mr. Relson's warnings on the performance of BAKR/PR warrant some additional
comment.
1. A well-tuned subroutine call can limit the number of registers that are
saved/restored. BAKR/PR saves/restores all 16 general-purpose registers, and
it always saves all 64-bits of the register, even if the
Some things to think about:
-- Recovery routines and retry points are tied to specific linkage stack
levels in the general case. Use of BAKR as a linkage can complicate that.
-- BAKR/PR is slower than using a typical savearea linkage.
-- You might find that use of BAKR by the caller poses an unne
In 2012, I did a presentation at SHARE in Atlanta on the details of the
dual-address-space (DAS) and linkage-stack (LS) architecture which includes
BAKR and PR. Most likely, this contains far more detail than any sane person
would want to know, but it's easier to digest than the description in
