Bug 1091 - questions and feedback on ls004 shift/add (and LD/ST-Shifted)
Summary: questions and feedback on ls004 shift/add (and LD/ST-Shifted)
Alias: None
Product: Libre-SOC's first SoC
Classification: Unclassified
Component: Specification (show other bugs)
Version: unspecified
Hardware: Other Linux
: --- enhancement
Assignee: Luke Kenneth Casson Leighton
URL: https://libre-soc.org/openpower/sv/rf...
Depends on: 1055
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Reported: 2023-05-25 11:22 BST by Luke Kenneth Casson Leighton
Modified: 2024-02-07 20:12 GMT (History)
2 users (show)

See Also:
NLnet milestone: NLnet.2022-08-051.OPF
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Description Luke Kenneth Casson Leighton 2023-05-25 11:22:55 BST

* DONE: change field name "sm" also uppercase
* DONE: change instruction name "s" not "sh"
* DONE: add 1.6 and 1.7 Field/Formats to RFC
* DONE: unit tests up-to-date
* response from OPF Tracker with ID [OPF][ISA] #200567]:

action log:

* https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=5a3f254
* https://git.libre-soc.org/?p=openpower-isa.git;a=commitdiff;h=b546ab1
* https://git.libre-soc.org/?p=openpower-isa.git;a=commitdiff;h=9ec4c1e
Comment 1 Luke Kenneth Casson Leighton 2023-05-25 11:25:28 BST
see https://bugs.libre-soc.org/show_bug.cgi?id=968#c23
Comment 2 Luke Kenneth Casson Leighton 2023-05-27 11:33:55 BST
moved from https://bugs.libre-soc.org/show_bug.cgi?id=968#c23

(In reply to Paul Mackerras from https://bugs.libre-soc.org/show_bug.cgi?id=968#c23)
> Hopefully this is the right place to submit feedback about ls004; if not
> then Luke could add a pointer to the right place to the OPF gitea issue.

done sorry.
> Comments from IBM architects regarding the proposal:
> The ls004 instructions use "sm" as the name of the shift-amount field. sm is
> not a split field, so the field name should be capitalized.

ahh now i know what capital/lower means.

> (I'm not sure
> what "sm" stands for. "shift minus (1)"? If yes, SHM1 might be a better
> name. (ls004 doesn't include a definition of the field for Section 1.6.3.))

yes this one isn't quite ready for submission, still in draft.
insights still really helpful.

we are trying to avoid yet another definition of "SH" but now i
look at the new Z23-Form it is separate so not likely to be confused

|  0-5  | 6-10 | 11-15 | 16-20 | 21-22 | 23-30 | 31 | Form     |
|  PO   | RT   |  RA   |  RB   |  SH   |  XO   | Rc | Z23-Form |

> An additional comment is that the architecture uses "s" to stand for "Shift"
> in Shift instruction mnemonics, not "sh" as in ls004. (ls003 uses "s".)

noted as action-point, ty.
Comment 3 Luke Kenneth Casson Leighton 2023-05-27 11:51:44 BST

* change field name "sm" to "SH"
* change instruction name to "sadd" not "shadd"
* add Formats/Fields for 1.6 and 1.7
Comment 4 Luke Kenneth Casson Leighton 2023-05-27 12:43:16 BST

* rename sm to SH for shift-and-add instructions in fields.text


* rename shadd to sadd
* rename sm to SH
* update CSV files with instruction definition
* move shadd unit tests to separate class