Bug 1090 - feedback on OPF SVP64 RFC for "bigint" instructions: ls003.bignum
Summary: feedback on OPF SVP64 RFC for "bigint" instructions: ls003.bignum
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: 1029
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Reported: 2023-05-25 01:14 BST by Luke Kenneth Casson Leighton
Modified: 2023-05-25 06:56 BST (History)
2 users (show)

See Also:
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
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Description Luke Kenneth Casson Leighton 2023-05-25 01:14:54 BST
questions and feedback needed on ls003.bignum
also see presentation bug #1029
Comment 1 Paul Mackerras 2023-05-25 06:56:15 BST
Comments from IBM architects regarding the proposal:

The ls003 FX instructions use RC, aliased as RS, as the second output. I think the architecture doesn't alias registers thus. And I think RS is never used as a target.

And for Load with Update instructions (which I think are the only FX instructions that currently have two outputs) the second output register is RA. And, for existing instructions that use RS, RS is in bits 6:10, not bits 21:25 as in ls003.