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specialize slice::fill to use memset when possible - #147457

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the8472:slice_fill_memset2
Oct 9, 2025
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specialize slice::fill to use memset when possible#147457
bors merged 1 commit into
rust-lang:masterfrom
the8472:slice_fill_memset2

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@the8472

@the8472the8472 commented Oct 7, 2025

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It helps const eval performance rust-lang/miri#4616, debug builds and the gcc backend.

Previously attempted in #83245 but reverted due to unsoundness #87891 around potentially-uninitialized types. This PR only handles primitives where the problem does not arise.

split off from #147294

@rustbotrustbot 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. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 7, 2025
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r? @scottmcm

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@the8472the8472 mentioned this pull request Oct 7, 2025
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RalfJung
RalfJung reviewed Oct 8, 2025
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Comment threadlibrary/core/src/slice/specialize.rs Outdated
@the8472
specialize slice::fill to use memset when possible
99ab27f
LLVM generally can do this on its own, but it helps miri and other backends.
@RalfJung

RalfJung commented Oct 8, 2025

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LGTM, r=me if you want but I'm not a libs reviewer.

@joboet

joboet commented Oct 8, 2025

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@bors r=@RalfJung,@joboet

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bors commented Oct 8, 2025

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📌 Commit 99ab27f has been approved by RalfJung,@joboet

It is now in the queue for this repository.

@borsbors 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 Oct 8, 2025
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Zalathar commented Oct 9, 2025

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(Removing extra @ from approved-by)

@bors r=RalfJung,joboet

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bors commented Oct 9, 2025

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💡 This pull request was already approved, no need to approve it again.

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bors commented Oct 9, 2025

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📌 Commit 99ab27f has been approved by RalfJung,joboet

It is now in the queue for this repository.

Zalathar added a commit to Zalathar/rust that referenced this pull request Oct 9, 2025
@Zalathar
Rollup merge ofrust-lang#147457- the8472:slice_fill_memset2, r=Ralf…
affd573
…Jung,joboet
specialize slice::fill to use memset when possible
It helps const eval performance rust-lang/miri#4616, debug builds and the gcc backend.
Previously attempted in rust-lang#83245 but reverted due to unsoundness rust-lang#87891 around potentially-uninitialized types. This PR only handles primitives where the problem does not arise.
split off from rust-lang#147294
@ZalatharZalathar mentioned this pull request Oct 9, 2025
Closed
bors added a commit that referenced this pull request Oct 9, 2025
@bors
Auto merge of#147510- Zalathar:rollup-zlcd471, r=Zalathar
5aba379
Rollup of 7 pull requests
Successful merges:
- #146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- #147373 (give a better example why `std` modules named like primitives are needed)
- #147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- #147457 (specialize slice::fill to use memset when possible)
- #147468 (Implement fs api set_times and set_times_nofollow)
- #147489 (Prefer to use repeat_n over repeat().take())
- #147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
@ZalatharZalathar mentioned this pull request Oct 9, 2025
Merged
bors added a commit that referenced this pull request Oct 9, 2025
@bors
Auto merge of#147512- Zalathar:rollup-p8kb5f7, r=Zalathar
acf2437
Rollup of 12 pull requests
Successful merges:
- #146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- #147373 (give a better example why `std` modules named like primitives are needed)
- #147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- #147420 (Add diagnostic items for `pub mod consts` of FP types)
- #147457 (specialize slice::fill to use memset when possible)
- #147467 (Fix double warnings on `#[no_mangle]`)
- #147470 (Clarify how to remediate the panic_immediate_abort error)
- #147480 (Do not invalidate CFG caches in CtfeLimit.)
- #147481 (format: some small cleanup)
- #147488 (refactor: Remove `LLVMRustInsertPrivateGlobal` and `define_private_global`)
- #147489 (Prefer to use repeat_n over repeat().take())
- #147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
@bors
bors merged commit 4e3e7ce into rust-lang:masterOct 9, 2025
10 checks passed
@rustbotrustbot added this to the 1.92.0 milestone Oct 9, 2025
rust-timer added a commit that referenced this pull request Oct 9, 2025
@rust-timer
Unrolled build for#147457
2a13e85
Rollup merge of #147457 - the8472:slice_fill_memset2, r=RalfJung,joboet
specialize slice::fill to use memset when possible
It helps const eval performance rust-lang/miri#4616, debug builds and the gcc backend.
Previously attempted in #83245 but reverted due to unsoundness #87891 around potentially-uninitialized types. This PR only handles primitives where the problem does not arise.
split off from #147294
github-actionsBot pushed a commit to model-checking/verify-rust-std that referenced this pull request Oct 10, 2025
@Zalathar
Rollup merge ofrust-lang#147457- the8472:slice_fill_memset2, r=Ralf…
2ce9fde
…Jung,joboet
specialize slice::fill to use memset when possible
It helps const eval performance rust-lang/miri#4616, debug builds and the gcc backend.
Previously attempted in rust-lang#83245 but reverted due to unsoundness rust-lang#87891 around potentially-uninitialized types. This PR only handles primitives where the problem does not arise.
split off from rust-lang#147294
RalfJung pushed a commit to RalfJung/miri that referenced this pull request Oct 13, 2025
@bors
Auto merge of #147512 - Zalathar:rollup-p8kb5f7, r=Zalathar
c6ea29f
Rollup of 12 pull requests
Successful merges:
- rust-lang/rust#146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- rust-lang/rust#147373 (give a better example why `std` modules named like primitives are needed)
- rust-lang/rust#147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- rust-lang/rust#147420 (Add diagnostic items for `pub mod consts` of FP types)
- rust-lang/rust#147457 (specialize slice::fill to use memset when possible)
- rust-lang/rust#147467 (Fix double warnings on `#[no_mangle]`)
- rust-lang/rust#147470 (Clarify how to remediate the panic_immediate_abort error)
- rust-lang/rust#147480 (Do not invalidate CFG caches in CtfeLimit.)
- rust-lang/rust#147481 (format: some small cleanup)
- rust-lang/rust#147488 (refactor: Remove `LLVMRustInsertPrivateGlobal` and `define_private_global`)
- rust-lang/rust#147489 (Prefer to use repeat_n over repeat().take())
- rust-lang/rust#147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
@github-actionsgithub-actionsBot mentioned this pull request Oct 15, 2025
Closed
@RalfJungRalfJung mentioned this pull request Oct 16, 2025
Closed
@folkertdevfolkertdev mentioned this pull request Oct 16, 2025
Merged
Kobzol pushed a commit to Kobzol/rustc_codegen_cranelift that referenced this pull request Dec 29, 2025
@bors
Auto merge of #147512 - Zalathar:rollup-p8kb5f7, r=Zalathar
ccff8fd
Rollup of 12 pull requests
Successful merges:
- rust-lang/rust#146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- rust-lang/rust#147373 (give a better example why `std` modules named like primitives are needed)
- rust-lang/rust#147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- rust-lang/rust#147420 (Add diagnostic items for `pub mod consts` of FP types)
- rust-lang/rust#147457 (specialize slice::fill to use memset when possible)
- rust-lang/rust#147467 (Fix double warnings on `#[no_mangle]`)
- rust-lang/rust#147470 (Clarify how to remediate the panic_immediate_abort error)
- rust-lang/rust#147480 (Do not invalidate CFG caches in CtfeLimit.)
- rust-lang/rust#147481 (format: some small cleanup)
- rust-lang/rust#147488 (refactor: Remove `LLVMRustInsertPrivateGlobal` and `define_private_global`)
- rust-lang/rust#147489 (Prefer to use repeat_n over repeat().take())
- rust-lang/rust#147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #147512 - Zalathar:rollup-p8kb5f7, r=Zalathar
5461966
Rollup of 12 pull requests
Successful merges:
- rust-lang/rust#146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- rust-lang/rust#147373 (give a better example why `std` modules named like primitives are needed)
- rust-lang/rust#147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- rust-lang/rust#147420 (Add diagnostic items for `pub mod consts` of FP types)
- rust-lang/rust#147457 (specialize slice::fill to use memset when possible)
- rust-lang/rust#147467 (Fix double warnings on `#[no_mangle]`)
- rust-lang/rust#147470 (Clarify how to remediate the panic_immediate_abort error)
- rust-lang/rust#147480 (Do not invalidate CFG caches in CtfeLimit.)
- rust-lang/rust#147481 (format: some small cleanup)
- rust-lang/rust#147488 (refactor: Remove `LLVMRustInsertPrivateGlobal` and `define_private_global`)
- rust-lang/rust#147489 (Prefer to use repeat_n over repeat().take())
- rust-lang/rust#147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #147512 - Zalathar:rollup-p8kb5f7, r=Zalathar
742a1da
Rollup of 12 pull requests
Successful merges:
- rust-lang/rust#146568 (Port the implemention of SIMD intrinsics from Miri to const-eval)
- rust-lang/rust#147373 (give a better example why `std` modules named like primitives are needed)
- rust-lang/rust#147419 (bootstrap: add `Builder::rustc_cmd` that includes the lib path)
- rust-lang/rust#147420 (Add diagnostic items for `pub mod consts` of FP types)
- rust-lang/rust#147457 (specialize slice::fill to use memset when possible)
- rust-lang/rust#147467 (Fix double warnings on `#[no_mangle]`)
- rust-lang/rust#147470 (Clarify how to remediate the panic_immediate_abort error)
- rust-lang/rust#147480 (Do not invalidate CFG caches in CtfeLimit.)
- rust-lang/rust#147481 (format: some small cleanup)
- rust-lang/rust#147488 (refactor: Remove `LLVMRustInsertPrivateGlobal` and `define_private_global`)
- rust-lang/rust#147489 (Prefer to use repeat_n over repeat().take())
- rust-lang/rust#147506 (compiletest: Isolate public APIs and minimize public surface area)
r? `@ghost`
`@rustbot` modify labels: rollup
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