rustc_scalable_vector(N)
#143924
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rustc_scalable_vector(N)
#143924
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rustbot has assigned @compiler-errors. Use |
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Some changes occurred in compiler/rustc_attr_parsing Some changes occurred in compiler/rustc_attr_data_structures Some changes occurred in compiler/rustc_passes/src/check_attr.rs Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr Some changes occurred to the CTFE / Miri interpreter cc @rust-lang/miri Some changes occurred to the platform-builtins intrinsics. Make sure the cc @antoyo, @GuillaumeGomez, @bjorn3, @calebzulawski, @programmerjake Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt Some changes occurred in compiler/rustc_codegen_ssa Some changes occurred in compiler/rustc_codegen_gcc changes to the core type system Some changes occurred to the CTFE machinery |
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I've changed this back to a draft and marked it as |
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workingjubilee
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Jul 14, 2025
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I do not intend to have repr(simd) survive this year, so I do not think this should be added.
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Could you elaborate? |
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I intend to replace it with an approach based on lang items for a variety of reasons, one of them being that to start with, the |
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That last scan-through should be all, unless something is revealed (made apparent?) by the next iteration, so @rustbot author |
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Seems good to me, r=me with rebase. |
Extend parsing of `ReprOptions` with `rustc_scalable_vector(N)` which optionally accepts a single literal integral value - the base multiple of lanes that are in a scalable vector. Can only be applied to structs. Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Extend well-formedness checking and HIR analysis to prohibit the use of scalable vectors in structs, enums, unions, tuples and arrays. LLVM does not support scalable vectors being members of other types, so these restrictions are necessary. Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Introduces `BackendRepr::ScalableVector` corresponding to scalable vector types annotated with `repr(scalable)` which lowers to a scalable vector type in LLVM. Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
LLVM doesn't handle stores on `<vscale x N x i1>` for `N != 16`, a type used internally in SVE intrinsics. Spilling to the stack to create debuginfo will cause errors during instruction selection. These types that are an internal implementation detail to the intrinsic, so users should never see them types and won't need any debuginfo. Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Scalable vectors cannot be members of ADTs and thus cannot be kept over await points in async functions.
Scalable vector types only work with the relevant target features enabled, so require this for any function with the types in its signature.
The `fmt::Debug` impl for `TyAndLayout<'a, Ty>'` requires `fmt::Display` on the `Ty` parameter. In `ArgAbi`, `TyAndLayout`'s Ty` is instantiated with a parameter that implements `TyAbiInterface`. `TyAbiInterface` only required `fmt::Debug` be implemented on `Self`, not `fmt::Display`, which meant that it wasn't actually possible to debug print `ArgAbi`.
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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@bors r=workingjubilee |
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☀️ Test successful - checks-actions |
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What is this?This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.Comparing 61cc47e (parent) -> 95a27ad (this PR) Test differencesShow 224 test diffsStage 0
Stage 1
Stage 2
(and 96 additional test diffs) Additionally, 28 doctest diffs were found. These are ignored, as they are noisy. Job group index
Test dashboardRun cargo run --manifest-path src/ci/citool/Cargo.toml -- \
test-dashboard 95a27adcf907bcc1046602c3746dad8cfdf3bf3f --output-dir test-dashboardAnd then open Job duration changes
How to interpret the job duration changes?Job durations can vary a lot, based on the actual runner instance |
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Finished benchmarking commit (95a27ad): comparison URL. Overall result: ❌✅ regressions and improvements - no action needed@rustbot label: -perf-regression Instruction countOur most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.
Max RSS (memory usage)Results (secondary 1.2%)A less reliable metric. May be of interest, but not used to determine the overall result above.
CyclesResults (secondary -1.7%)A less reliable metric. May be of interest, but not used to determine the overall result above.
Binary sizeResults (primary 0.1%, secondary 0.0%)A less reliable metric. May be of interest, but not used to determine the overall result above.
Bootstrap: 478.546s -> 479.485s (0.20%) |
This was referenced Dec 16, 2025
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Supercedes #118917.
Initial experimental implementation of rust-lang/rfcs#3838. Introduces a
rustc_scalable_vector(N)attribute that can be applied to types with a single[$ty]field (foru{16,32,64},i{16,32,64},f{32,64},bool).rustc_scalable_vectortypes are lowered to scalable vectors in the codegen backend.As with any unstable feature, there will necessarily be follow-ups as we experiment and find cases that we've not considered or still need some logic to handle, but this aims to be a decent baseline to start from.
See #145052 for request for a lang experiment.