Bug 1054

Summary:	questions and feedback (v2) on OPF RFC ls012
Product:	Libre-SOC's first SoC	Reporter:	Luke Kenneth Casson Leighton <lkcl>
Component:	Specification	Assignee:	Dmitry Selyutin <ghostmansd>
Status:	RESOLVED FIXED
Severity:	enhancement	CC:	ghostmansd, libre-soc-isa
Priority:	---
Version:	unspecified
Hardware:	PC
OS:	Linux
URL:	https://libre-soc.org/openpower/sv/rfc/ls012/
See Also:	https://bugs.libre-soc.org/show_bug.cgi?id=1051 https://bugs.libre-soc.org/show_bug.cgi?id=1055 https://bugs.libre-soc.org/show_bug.cgi?id=1068
NLnet milestone:	NLnet.2022-08-051.OPF	total budget (EUR) for completion of task and all subtasks:	2500
budget (EUR) for this task, excluding subtasks' budget:	2500	parent task for budget allocation:	1012
child tasks for budget allocation:		The table of payments (in EUR) for this task; TOML format:	lkcl=1000 red={amount=1000,submitted=2023-10-17,paid=2023-11-10} ghostmansd={amount=500,submitted=2024-01-18,paid=2024-01-29}
Bug Depends on:	1099, 1052, 1055
Bug Blocks:

Description Luke Kenneth Casson Leighton 2023-04-11 18:20:25 BST

this bugreport tracks questions comments and feedback for v2 of ls012.
included is revisions of LD/ST-shifted, LD/ST-shifyed-Postincrement, and a few
other useful status columns (such as whether the instruction
has binutils support yet).

--

TODO:

* DONE - add LD/ST-shifted table from ls004
* DONE - add a binutils column with whether added support or not

Comment 1 Luke Kenneth Casson Leighton 2023-04-12 13:30:52 BST

https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=0bc47c95b9b77d2237d36e23c1d45f233f9f6326

added LD/ST-Indexed-Shifted table to optable.csv, and add description
into group of instructions. whether a decision is made to include them
or not is entirely up to the ISA WG.

Comment 2 Luke Kenneth Casson Leighton 2023-04-13 11:15:22 BST

i've also added LDST-Shifted-Postinc (!) which is another 37
instructions (!) very deliberately to raise awareness of the
problem of opcode allocation, but also to solicit, under
"Due Diligence", a response from the ISA WG as to why they
should or should not be included.

i would expect the answer "eek!" but then that helps make
te case for shift-and-add as a much more palatable alternative.

Comment 3 Luke Kenneth Casson Leighton 2023-04-26 14:37:37 BST

added a new column "binutils"
https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=1612a779c718fef1bec4f0384d4121119665f32e

indicates if the instruction has been added and/or needs updating.

Comment 4 Dmitry Selyutin 2023-04-26 15:54:51 BST

Thank you for this table! I think with a small tuning I can re-use it to filter it for binutils.

Comment 5 Luke Kenneth Casson Leighton 2023-10-17 13:31:34 BST

this is a "summary" RFC and has served (still serves) an incredibly valuable
purpose well beyond its original intention: providing *project* wide summaries
and tables sorted by different criteria.