Re: [PATCH 0/6] s390: Add missing extended mnemonics

[Jens Remus <jremus@linux.ibm.com>]

Hello Nick,

Am 22.11.2023 um 13:13 schrieb Nick Clifton:
>> This patch series adds the following extended mnemonics (grouped by
>> function) to the s390 target architecture:
>> - jc, jcth
>> - lfi, llgfi, llghi
>> - notr, notgr
>> - risbhgz, risblgz
>> - rnsbgt, rosbgt, rxsbgt

...

>> Patches 1-3 are preparatory changes. Patch 4 aligns the optional operand
>> definition. Patch 5 adds the missing extended mnemonics. Patch 6 corrects
>> an instruction name.

...

> Patch series approved - please apply.

Thanks! Andreas will take care.

> Do these new instructions have a name to cover them as a whole ?
> I am thinking that it would be nice to have an entry in the gas/NEWS
> file that says something like "add support for the XXX extension to the
> s390x architecture".

No, these extended mnemonics were simply missed to be added over time. I 
did a cross check against the latest version of the IBM z/Architecture 
Principles of Operation specification to identify them.

Extended mnemonics are purely syntactic sugar and actually assemble into 
a base mnemonic. The identical instruction could be coded by using the 
existing base mnemonic instead of the new extended mnemonic. The 
disassembler for s390 tries to disassemble into the extended mnemonic, 
if it is not a simple alias, which makes the disassembly more human 
readable.

> One other, minor thing.  I tried to look at the documentation that
> you referenced in patch 5:
> 
>  > Add extended mnemonics specified in the z/Architecture Principles of
>  > Operation [1] and z/Architecture Reference Summary [2], that were
>  > previously missing from the opcode table.
> 
>  > [1] IBM z/Architecture Principles of Operation, SA22-7832-13,
>  >    https://www.ibm.com/support/pages/zarchitecture-principles-operation
>  > [2] IBM z/Architecture Reference Summary, SA22-7871-11,
>  >    https://www.ibm.com/support/pages/zarchitecture-reference-summary
> 
> I found that link [2] diverts to a "500: Internal Server Error" page
> and link [1] would not let me download the document without first
> registering for an IBMid, which I can do, but it is not really Open
> Source friendly...

Thanks for the hint! I have sent a V2 of my patches 3 and 4 with direct 
links to the documentation. These should work without an IBMid.

Regards,
Jens
-- 
Jens Remus
Linux on Z Development (D3303) and z/VSE Support
+49-(0)7031-16-1128 Office
JREMUS@de.ibm.com

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