One use case:
It has been mentioned here that EXECUTE'd instructions are expensive.
So for variable length MVCs up to 16 bytes, an executed MVC could be replaced
by VLL/VSTL.
Robert Ngan
DXC Luxoft
-----Original Message-----
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf
Of Ngan, Robert (DXC Luxoft)
Sent: Thursday, September 30, 2021 15:30
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: Vector Instructions
Thank you Dan,
This is a lot easier to understand than what's in the Principles of Operations.
I've only gotten thru to Chapter 21 and I've already found three cases where I
can use vector instructions in our code.
One nit (nothing to do with your Powerpoints), the third VPKZ/VUPKZ operand
should be optional, with the assembler defaulting to the length of implied
length of the second operand. Having to always code:
VPKZ 1,Source,L'Source-1
VUPKZ 2,Target,L'Target-1
will get tedious really fast.
Robert Ngan
DXC Luxoft
-----Original Message-----
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf
Of Dan Greiner
Sent: Tuesday, September 28, 2021 23:06
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Vector Instructions
I have put together a series of PowerPoint files illustrating the operation of
the vector-facility instructions ... a sort of graphic-novel version of
Chapters 21-25 of the PoO. Since the Assembler List doesn't accept file
uploads, you can find the material on my Google drive:
https://clicktime.symantec.com/3ReigZgh6pPBGgrWU1YpCps7Vc?u=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1O_RWJJGMX-tLR0AxEYk4QARxJhi_0MVV%2Fview%3Fusp%3Dsharing
Background:
Although I edited much of the vector-facility material that was incorporated
into the z13 z/Architecture Principles of Operation back in 2015, I was not the
engineer responsible for the material, and I never bothered to study it very
closely. Since I retired in 2017, I've been looking more closely, and recently
I started scribbling some notes on a few instructions that puzzled me ... which
turned into a few PowerPoint slides ... which eventually turned into a 300+
slide opus.
The PowerPoint files were prepared using a template that I've used in the past
for presentations at SHARE conferences. Like other presentations illustrating
new architecture, the slides make extensive use of animation to illustrate the
operation and data flow. So, they are best viewed in slide-show mode. However,
the real meat of the material is in the presenter notes for each slide (with a
two monitors, you can see both simultaneously).
There are separate PowerPoint files including an introduction, and a file for
each chapter of the PoO containing vector instructions (7, and 21-25). In the
Chapter 21 file, there are separate slides illustrating the operation of an
instruction with each element size. By the time I got to Chapter 22, my carpals
were acting up, so the slides are mostly limited to a single element size.
At the end of a SHARE presentation, I would (time permitting) solicit questions
from the audience, and extended discussions might continue at the SHARE
Committee for Informal Discussions (SCIDs, a.k.a. an open bar). Considering the
content of these slides, it would likely take days to present one chapter's
worth ... by which time, the SCIDs would have long since run out of liquor
before any interesting questions could be posed.
As it is unlikely this material will make it to the SHARE agenda any time soon,
I thought I'd just share it directly. You are welcome to use it for your own
enlightenment, but I will have strong words with anyone who tries to make a
buck off of it.
As one might expect, much of the development involved a lot of copy-and-paste
operations on a PC, so there may be a few copy-and-paste type of errors lurking
about. If you have questions or meaningful comments as to clarity or accuracy,
you're welcome to contact me via email. However, is you simply don't like the
fonts, colors, or animation ... well ... have a nice day.
