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sayantn opened this issue Mar 4, 2025 · 0 comments
Open
3 tasks

Tracking Issue for movrs target feature #137976

sayantn opened this issue Mar 4, 2025 · 0 comments
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C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.

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@sayantn
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sayantn commented Mar 4, 2025 •
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Feature gate: #![feature(movrs_target_feature)]

This is a tracking issue for the x86(64) target feature movrs. It includes 2 instructions - MOVRS and PREFETCHRST2. These behave as normal MOV and PREFETCHW instructions, just with the "read-shared" hint. This, as suggested by the name, is purely a hint to the processor that the data loaded/stored by the instruction is likely to get accessed by multiple processors.

Public API

The movrs target feature (which enables the MOVRS and PREFETCHRST2 instructions) and the following stdarch intrinsics

  • _movrs_i8
  • _movrs_i16
  • _movrs_i32
  • _movrs_i64
  • _m_prefetchrs

Steps / History

  • Implementation
  • Final comment period (FCP)1
  • Stabilization PR

Implementation History

Unresolved Questions

  • How does this interact with the memory model? The Intel specification strongly suggests that this is just a hint to the processor, but we need to check to be sure.

Footnotes

  1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩
@sayantn sayantn added C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Mar 4, 2025
@sayantn sayantn mentioned this issue Mar 4, 2025
Merged
@sayantn sayantn mentioned this issue Apr 1, 2025
Merged
Zalathar added a commit to Zalathar/rust that referenced this issue Apr 2, 2025
@Zalathar
Rollup merge of rust-lang#138003 - sayantn:new-amx, r=Amanieu
5b0f658 
Add the new `amx` target features and the `movrs` target feature

Adds 5 new `amx` target features included in LLVM20. These are guarded under `x86_amx_intrinsics` (rust-lang#126622)

 - `amx-avx512`
 - `amx-fp8`
 - `amx-movrs`
 - `amx-tf32`
 - `amx-transpose`

Adds the `movrs` target feature (from rust-lang#137976).

`@rustbot` label O-x86_64 O-x86_32 T-compiler A-target-feature
r? `@Amanieu`
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Apr 2, 2025
@rust-timer
Unrolled build for rust-lang#138003
46d8f7b 
Rollup merge of rust-lang#138003 - sayantn:new-amx, r=Amanieu

Add the new `amx` target features and the `movrs` target feature

Adds 5 new `amx` target features included in LLVM20. These are guarded under `x86_amx_intrinsics` (rust-lang#126622)

 - `amx-avx512`
 - `amx-fp8`
 - `amx-movrs`
 - `amx-tf32`
 - `amx-transpose`

Adds the `movrs` target feature (from rust-lang#137976).

`@rustbot` label O-x86_64 O-x86_32 T-compiler A-target-feature
r? `@Amanieu`
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