Can you temporarily save one register, load it register with the 4(R13)
and use a CFI?
On 2021-11-29 5:51 p.m., Mark Hammack wrote:
So an interesting dilemma:
I have a macro that switches between a regular (24/31 bit style) save area
and an extended (64 bit "F4SA") save area. Before saving the registers, I
am checking whether the current save area is old (24/31 bit) or new (64
bit) save area. The original code used CLC =C'F4SA',4(R13) to check
(since it is all our code, I don't need to worry about the other 64 bit
save area formats). However, that implies a literal pool within 4k of the
subroutine entry point (R15 at this point). I could add a 4 byte literal
to the macro and then branch around it. The other option I thought of
which removes the necessity of a base register is to use CLHHSI
4(R13),C'F4'/JNE .../CLHHSI 6(R13),C'SA'/JNE ... However, this is
confusing and since there are multiple points in the macro where I need the
F4SA literal, I'll probably go with door number one.
If only there were 20 bit displacement options for CLC and MVC...(LRL,
LARL, LAY, etc. have come in handy for reducing the number of LTORGS in the
programs, especially for =A(address) type literals).
*Mark*
On Mon, Nov 29, 2021 at 4:06 PM Seymour J Metz<sme...@gmu.edu> wrote:
"When control is returned to your control section from the called control
section, registers 2-14 contain the same information they contained when
control was passed, as long as system conventions are followed."
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
Gary Weinhold
Senior Application Architect
DATAKINETICS | Data Performance & Optimization
Phone:+1.613.523.5500 x216
Email: weinh...@dkl.com
Visit us online at www.DKL.com
E-mail Notification: The information contained in this email and any
attachments is confidential and may be subject to copyright or other
intellectual property protection. If you are not the intended recipient, you
are not authorized to use or disclose this information, and we request that you
notify us by reply mail or telephone and delete the original message from your
mail system.
From: IBM Mainframe Assembler List [ASSEMBLER-LIST@LISTSERV.UGA.EDU] on
behalf of Ngan, Robert (DXC Luxoft) [robert.n...@dxc.com]
Sent: Monday, November 29, 2021 3:57 PM
To:ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: Base-less macros
The assembler services guide doesn't specify what is in (bottom half of)
R14 upon return.
Also, on return to an AMODE(64) routine via BASSM/BSM, R14 would have the
low-order bit set.
Robert
-----Original Message-----
From: IBM Mainframe Assembler List<ASSEMBLER-LIST@LISTSERV.UGA.EDU> On
Behalf Of Paul Gilmartin
Sent: Monday, November 29, 2021 14:01
To:ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: Base-less macros
On Nov 29, 2021, at 12:41:51, Ngan, Robert (DXC Luxoft) wrote:
DON'T DO THAT!
I had to find/redo all our code that did this when our subroutine
return logic was changed to use a BIC instruction.
Which of you violated standard linkage conventions?
My understanding is that R14 is expected to point to the instruction after
the CALL; R15 to the ENTRY point. Either may be changed by an embedded
CALL and should be treated as volatile. RETURN should use LM to retrieve
the value of R14, etc.
-----Original Message-----
From: Steve Smith
Sent: Thursday, November 25, 2021 13:49
My suggestion of using R14 for the base was because it's already set by
the call to the subroutine.
-- gil
