rust-lang / rust-lang/rust

How should we handle matrix ABIs?

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A-ABI C-discussion E-needs-investigation O-AArch64 O-PowerPC O-x86_64 T-compiler
Dominant language
Rust
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Description

Some CPU architectures have developed "matrix extensions". These are sometimes equivalent to "vectors, but bigger" in terms of how the ABI should be handled (reusing the same architectural state, thus having similar concerns). But not always! They may use entirely different architectural state, usually entirely "caller-save" (i.e. always "volatile" or "call-clobbered").

AArch64

Scalable Matrix Extensions

PowerPC

MMA

x86

AMX

References

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the linked Rust issues 133146, 131800, and 126622, along with the ARM SME, PowerPC MMA, and x86 AMX references. Compare how each matrix extension uses architectural state and whether it introduces types such as x86's amx_tile. Done requires an agreed ABI-handling policy covering the listed architectures.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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