WRT:
"A gentle reminder on terminology: The term
"JUMP" appears neither in the PoO nor in the
z/Architecture Reference Summary (SA22-7832).
What you refer to as "JAS (jump and save)" is
simply reflecting the extended mnemonic for BRANCH RELATIVE AND SAVE (BRAS)."
The PoOps has some inconsistencies... One that I
find rather irritating is the presences of
extended mnemonics for a large number of newer
instructions, but the omission of same for all of
the BC, BRC, BRAS and related instructions.
Yes, I am quite aware that I included redundant
entries in my list. I didn't care because it was beside the point.
Speaking of fake mnemonics... What is the
difference between "extended mnemonics" (such as
CGIJNE) and "alternative mnemonics" (such as
JAS)? Is it that one is documented only in the
PoOp and the other only in HLASM Ref?
(FWIW, I find both books to be abysmal documents!)
(There. That ought to create a firestorm!)
Dave
At 2/10/2022 01:27 PM, Dan Greiner wrote:
Having learned this stuff in the 1970s before
the linkage stack showed up in the late 1980s
I was accustomed to hearing them called simply
"linkage instructions." For the common usage of
application programmers who need a simple
instruction to branch to Oz while leaving a
footprint of how to get back to Kansas, that's probably sufficient.
.
The z/Architecture Principles of Operation
(SA22-7832-10) refers to such instruction in a
section labelled "Subroutine Linkage without the
Linkage Stack" (p. 5-16 onward), with the simple
stuff like BAL[R], BAS[R] and friends called
"Simple Branch Instructions". This text shows
the awkwardness that crept into the architecture
when various commonly-used terms get redeployed
for other purposes. [A brief aside: During the
design of the S/360, the designers deliberately
eschewed a stack architecture in favor of the
chained save-area approach. With the advent of
ESA, they changed their minds (sort of) and implemented a linkage stack.]
A gentle reminder on terminology: The term
"JUMP" appears neither in the PoO nor in the
z/Architecture Reference Summary (SA22-7832).
What you refer to as "JAS (jump and save)" is
simply reflecting the extended mnemonic for BRANCH RELATIVE AND SAVE (BRAS).
