stabilize s390x vector registers by folkertdev · Pull Request #154184 · rust-lang/rust

folkertdev · 2026-03-21T17:47:44Z

tracking issue: #133416
reference PR: rust-lang/reference#2215

Stabilizes s390x vector registers, e.g.

unsafefnvreg_128(x:i128) -> i128{let y;asm!("vlr {}, {}", out(vreg) y, in(vreg) x);
y
}

The types that are accepted for vreg registers are

all float types f16, f32, f64, f128
integer types i32, i64 and i128 and their unsigned counterparts
integer vector types i8x16, i16x8, i32x4, i64x2 and their unsigned counterparts
float vector types f16x8, f32x4 and f64x2

Support for all of these is tested in https://github.com/rust-lang/rust/blob/main/tests/assembly-llvm/asm/s390x-types.rs, and the types correspond with the LLVM definition in https://github.com/llvm/llvm-project/blob/df9eb79970c012990e829d174d181d575d414efe/llvm/lib/Target/SystemZ/SystemZRegisterInfo.td#L312-L339

The f16, f16x8 and f128 types are unstable, and so can't be used on stable in practice. They do show up in some error messages though.

vreg was previously only accepted as a clobber.

Currently the vector types in core::arch::s390x are still unstable. Separately stabilizing vreg is still useful because scalar types can also be put into vregs.

Implementation history

cc @uweigand @taiki-e
r? @Amanieu

traviscross · 2026-03-25T15:14:00Z

Thanks @folkertdev; I'll be looking to see that @Amanieu confirms this is OK after the back and force.

@rfcbot fcp merge lang

rust-rfcbot · 2026-03-25T15:14:04Z

Team member @traviscross has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

scottmcm · 2026-03-25T15:14:43Z

Happy to trust @Amanieu for this.

@rfcbot reviewed

rust-rfcbot · 2026-03-25T15:14:59Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rust-rfcbot · 2026-04-04T15:16:06Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

folkertdev · 2026-04-08T10:54:24Z

@bors r=Amanieu

rust-bors · 2026-04-08T10:54:27Z

📌 Commit e182fef has been approved by Amanieu

It is now in the queue for this repository.

…uwer Rollup of 15 pull requests Successful merges: - #153995 (Use convergent attribute to funcs for GPU targets) - #154184 (stabilize s390x vector registers) - #151898 (constify DoubleEndedIterator) - #154235 (remove unnecessary variables and delimiter check) - #154473 (move borrow checker tests) - #154745 (Replace span_look_ahead with span_followed_by) - #154778 (make field representing types invariant over the base type) - #154867 (Fix private fields diagnostics and improve error messages) - #154879 (Don't store `pattern_ty` in `TestableCase`) - #154910 (Suppress `unreachable_code` lint in `derive(PartialEq, Clone)`) - #154923 (Fix ICE in next-solver dyn-compatibility check) - #154934 (Add getters for `rustc_pattern_analysis::constructor::Slice` fields) - #154938 (match exhaustiveness: Show the guard exhaustivity note only when it's the guards alone that cause non-exhaustiveness) - #154961 (Use derived impl for `GappedRange` subdiagnostic) - #154980 (rustc-dev-guide subtree update)

@uweigand

Rollup merge of #154184 - folkertdev:stabilize-s390x-vector-registers, r=Amanieu stabilize s390x vector registers tracking issue: #133416 reference PR: rust-lang/reference#2215 Stabilizes s390x vector registers, e.g. ```rust unsafe fn vreg_128(x: i128) -> i128 { let y; asm!("vlr {}, {}", out(vreg) y, in(vreg) x); y } ``` The types that are accepted for vreg registers are - all float types `f16`, `f32`, `f64`, `f128` - integer types `i32`, `i64` and `i128` and their unsigned counterparts - integer vector types `i8x16`, `i16x8`, `i32x4`, `i64x2` and their unsigned counterparts - float vector types `f16x8`, `f32x4` and `f64x2` Support for all of these is tested in https://github.com/rust-lang/rust/blob/main/tests/assembly-llvm/asm/s390x-types.rs, and the types correspond with the LLVM definition in https://github.com/llvm/llvm-project/blob/df9eb79970c012990e829d174d181d575d414efe/llvm/lib/Target/SystemZ/SystemZRegisterInfo.td#L312-L339 The `f16`, `f16x8` and `f128` types are unstable, and so can't be used on stable in practice. They do show up in some error messages though. `vreg` was previously only accepted as a clobber. --- Currently the vector types in `core::arch::s390x` are still unstable. Separately stabilizing `vreg` is still useful because scalar types can also be put into `vreg`s. ## Implementation history - #131664 - #150826 cc @uweigand @taiki-e r? @Amanieu

…uwer Rollup of 15 pull requests Successful merges: - rust-lang/rust#153995 (Use convergent attribute to funcs for GPU targets) - rust-lang/rust#154184 (stabilize s390x vector registers) - rust-lang/rust#151898 (constify DoubleEndedIterator) - rust-lang/rust#154235 (remove unnecessary variables and delimiter check) - rust-lang/rust#154473 (move borrow checker tests) - rust-lang/rust#154745 (Replace span_look_ahead with span_followed_by) - rust-lang/rust#154778 (make field representing types invariant over the base type) - rust-lang/rust#154867 (Fix private fields diagnostics and improve error messages) - rust-lang/rust#154879 (Don't store `pattern_ty` in `TestableCase`) - rust-lang/rust#154910 (Suppress `unreachable_code` lint in `derive(PartialEq, Clone)`) - rust-lang/rust#154923 (Fix ICE in next-solver dyn-compatibility check) - rust-lang/rust#154934 (Add getters for `rustc_pattern_analysis::constructor::Slice` fields) - rust-lang/rust#154938 (match exhaustiveness: Show the guard exhaustivity note only when it's the guards alone that cause non-exhaustiveness) - rust-lang/rust#154961 (Use derived impl for `GappedRange` subdiagnostic) - rust-lang/rust#154980 (rustc-dev-guide subtree update)

folkertdev added the I-lang-nominated Nominated for discussion during a lang team meeting. label Mar 21, 2026

rustbot assigned Amanieu Mar 21, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Mar 21, 2026

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folkertdev force-pushed the stabilize-s390x-vector-registers branch from 2986c81 to ba604f5Compare March 21, 2026 18:30

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stabilize s390x vector registers
e182fef

folkertdev force-pushed the stabilize-s390x-vector-registers branch from ba604f5 to e182fefCompare March 21, 2026 19:58

Amanieu reviewed Mar 22, 2026
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Comment threadcompiler/rustc_target/src/asm/s390x.rs

folkertdev mentioned this pull request Mar 22, 2026
stabilize s390x vector registers rust-lang/reference#2215
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taiki-e mentioned this pull request Mar 25, 2026
Tracking Issue for asm_experimental_reg #133416
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2 tasks

traviscross added P-lang-drag-1 Lang team prioritization drag level 1. https://rust-lang.zulipchat.com/#narrow/channel/410516-t-lang T-lang Relevant to the language team labels Mar 25, 2026

rust-rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Mar 25, 2026

rust-rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Mar 25, 2026

Amanieu approved these changes Mar 25, 2026
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rustbot mentioned this pull request Apr 4, 2026
Tracking issue for release notes of #154184: stabilize s390x vector registers #154814
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rust-borsBot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 8, 2026

JonathanBrouwer mentioned this pull request Apr 8, 2026
Rollup of 15 pull requests #154985
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rust-borsBot merged commit 3e027ff into rust-lang:mainApr 8, 2026
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rustbot added this to the 1.96.0 milestone Apr 8, 2026

BoxyUwU mentioned this pull request May 12, 2026
Draft release notes for 1.96.0 #156512
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folkertdev mentioned this pull request Jun 8, 2026
s390x vector facilities support #130869
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