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Removing reg-reg-reg variants of permutation instructions. #63

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ben-marshall opened this issue Nov 6, 2020 · 8 comments
Closed

Removing reg-reg-reg variants of permutation instructions. #63

ben-marshall opened this issue Nov 6, 2020 · 8 comments
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specification Improvements or additions to the specification
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RISC-V Scalar Cryptography Extensions

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@ben-marshall
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ben-marshall commented Nov 6, 2020 •
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A/O the meeting on Nov 6'th 2020, we have decided to remove the reg-reg-reg variants of:

  • gorc
  • grev
  • shufl
  • unshufl

From the Crypto extension because we do not have a use case for them. They are still expected to exist in Bitmanip.

We are keeping the reg-reg-reg variants of

  • ror
  • rol

Because we anticipate there may be a use case for them in the future, and they are extremely cheap to implement given the presence of the immediate variants.
@ben-marshall ben-marshall added the specification Improvements or additions to the specification label Nov 6, 2020
@ben-marshall ben-marshall self-assigned this Nov 6, 2020
@ben-marshall ben-marshall added this to Instruction Specification in RISC-V Scalar Cryptography Extensions Nov 6, 2020
@JamesKenneyImperas
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Morning Ben,

A couple of clarifications:

  1. When you say the instructions are removed, I assume you mean only from the K extension, not the B extension. I'm pretty sure this is the case, but just checking.
  2. On the spreadsheet you just updated, I notice that gorciw is also marked as not present, but this wasn't mentioned in the list above. Is it also removed?

Thanks,

James.

@JamesKenneyImperas
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Ah no, I think I misread the spreadsheet. It's just not in a feature subset.

@JamesKenneyImperas
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Correction, it does seem to be removed. Aaargh.

@ben-marshall
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Hi James

  1. Yes, removed from the K extension. The B extension remains unchanged. I'll update my issue description above to clarify.
  2. I will double check with @mjosaarinen about gorciw it is currently included in the scalar K spec, I think that the spreadsheet might just have a typo.

Broadly, we are removing the 3-reg address versions of gorc, grev, shufl, unshufl, but are keeping all of the immediate variants gorci, grevi, shufli, and unshufli.

@mjosaarinen
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Hi,

Talked about this with Ben.. I think we really only need a subset of these immediate variants (rev.b, rev8, zip, unzip) .. apologies for the confusion, I'm to blame for some of the things in that spreadsheet.

Cheers,

  • markku

ben-marshall added a commit that referenced this issue Nov 10, 2020
@ben-marshall
spec: #63 - remove reg-reg variants of grev/gorc/[un]shfl
ebf6e68 
- As agreed at meeting, remove register register variants of the
  grev, gorc and [un]shfl instructions.

  - We do not have a use case for them.

- Be explicit about exactly which variants of the immediate instructions
  we require, and which canonical instructions they map onto.

- Also do some housekeeping to minimise the number of latex files.

 On branch dev/next-release
 Your branch is up-to-date with 'origin/dev/next-release'.

 Changes to be committed:
	modified:   doc/riscv-crypto-spec-scalar.tex
	modified:   doc/tex/sec-scalar-bitmanip.tex
	deleted:    doc/tex/sec-scalar.tex

 Changes not staged for commit:
	modified:   extern/riscv-compliance (modified content)
	modified:   extern/riscv-gnu-toolchain (modified content)
	modified:   extern/riscv-isa-sim (modified content)
	modified:   extern/riscv-opcodes (modified content)
	modified:   extern/sail-riscv (modified content, untracked content)

 Untracked files:
	doc/tex/sec-scalar-timing.tex
ben-marshall added a commit that referenced this issue Nov 10, 2020
@ben-marshall
spec: #63 - detail data-independent latency requirements.
2d0bdde 
 On branch dev/next-release
 Your branch is ahead of 'origin/dev/next-release' by 1 commit.
   (use "git push" to publish your local commits)

 Changes to be committed:
	modified:   doc/riscv-crypto-spec-scalar.tex
	new file:   doc/tex/sec-scalar-timing.tex

 Changes not staged for commit:
	modified:   extern/riscv-compliance (modified content)
	modified:   extern/riscv-gnu-toolchain (modified content)
	modified:   extern/riscv-isa-sim (modified content)
	modified:   extern/riscv-opcodes (modified content)
	modified:   extern/sail-riscv (modified content, untracked content)
@ben-marshall
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@JamesKenneyImperas - the new v0.7.2-scalar specification release should detail all of this explicitly. I'll leave this issue open for now in case there are other questions?

@JamesKenneyImperas
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Hi Ben,

I think this is now clear to me - thanks.

James.

@ben-marshall
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Hi James
Glad to hear it, I'll close this for now then.
Cheers,
Ben

RISC-V Scalar Cryptography Extensions automation moved this from Instruction Specification to Finished Tasks Nov 16, 2020
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