rustc_target: Adjust RISC-V feature implication #140139

a4lg · 2025-04-22T01:27:05Z

This commit adjusts feature implication of the RISC-V ISA for better feature detection from the user perspective.

The main rule is:

If the feature A is a functional superset of the feature B (A ⊃ B),
A is to imply B, even if this implication is not on the manual.

Such implications (not directly written in the ISA manual) are commented as A ⊃ B
which means "A is a (functional) superset of B".

Zbc → Zbkc (add as a superset)
The Zbkc extension is a subset of the Zbc extension (Zbc minus clmulr instruction).
Zkr → (nothing) (remove dependency to Zicsr)
Implication to the Zicsr extension is removed because (although nearly harmless), the Zkr extension (or the seed CSR section) defines its own subset of the Zicsr extension (guaranteed to work against the seed CSR which needs read/write access).
Zvbb → Zvkb (comment as a superset)
This implication was already there but not denoted as a functional superset. This commit adds the comment.
Zvfh → Zvfhmin (comment as a superset)
This is similar to the case above (Zvbb → Zvkb).
Zvfh → Zve32f (add implication per the ISA specification)
This dependency is on the ISA manual but was missing (due to the fact that Zvfh indirectly implies Zve32f on the current implementation through Zvfh → Zvfhmin which is a functional relation). This commit ensures that this is also ISA-compliant in the source code level (there's no functional changes though).
Zvknhb → Zvknha (add as a superset)
The Zvknhb extension (SHA-256 / SHA-512) is a functional superset of the Zvknha extension (SHA-256 only).

Tracking issue for RFC 2045: improving #[target_feature] #44839
(riscv_target_feature)
RISC-V: riscv_hwprobe-based feature detection on Linux / Android stdarch#1770
(synchronized with stdarch's latest RISC-V implication logic)

@rustbot r? @Amanieu
@rustbot label +T-compiler +O-riscv +A-target-feature

This commit adjusts feature implication of the RISC-V ISA for better feature detection from the user perspective. The main rule is: If the feature A is a functional superset of the feature B (A ⊃ B), A is to imply B, even if this implication is not on the manual. Such implications (not directly referred in the ISA manual) are commented as "A ⊃ B" which means "A is a (functional) superset of B". 1. Zbc → Zbkc (add as a superset) The Zbkc extension is a subset of the Zbc extension (Zbc - "clmulr" instruction == Zbkc) 2. Zkr → (nothing) (remove dependency to Zicsr) Implication to the Zicsr extension is removed because (although nearly harmless), the Zkr extension (or the "seed" CSR section) defines its own subset of the Zicsr extension. 3. Zvbb → Zvkb (comment as a superset) This implication was already there but not denoted as a functional superset. This commit adds the comment. 4. Zvfh → Zvfhmin (comment as a superset) This is similar to the case above (Zvbb → Zvkb). 5. Zvfh → Zve32f (add implication per the ISA specification) This dependency is on the ISA manual but was missing (due to the fact that Zvfh indirectly implies Zve32f on the current implementation through Zvfh → Zvfhmin, which is a functional relation). This commit ensures that this is *also* ISA-compliant in the source code level (there's no functional changes though). 6. Zvknhb → Zvknha (add as a superset) The Zvknhb extension (SHA-256 / SHA-512) is a functional superset of the Zvknha extension (SHA-256 only).

compiler/rustc_target/src/target_features.rs

Amanieu · 2025-04-23T21:28:20Z

@bors r+ rollup

bors · 2025-04-23T21:28:23Z

📌 Commit 2ef4f78 has been approved by Amanieu

It is now in the queue for this repository.

… r=Amanieu rustc_target: Adjust RISC-V feature implication This commit adjusts feature implication of the RISC-V ISA for better feature detection from the user perspective. The main rule is: * If the feature `A` is a functional superset of the feature `B` (`A ⊃ B`), `A` is to imply `B`, even if this implication is not on the manual. Such implications (not directly written in the ISA manual) are commented as `A ⊃ B` which means "`A` is a (functional) superset of `B`". 1. `Zbc` → `Zbkc` (add as a superset) The `Zbkc` extension is a subset of the `Zbc` extension (`Zbc` minus `clmulr` instruction). 2. `Zkr` → (nothing) (remove dependency to `Zicsr`) Implication to the `Zicsr` extension is removed because (although nearly harmless), the `Zkr` extension (or the `seed` CSR section) defines its own subset of the `Zicsr` extension (guaranteed to work against the `seed` CSR which needs read/write access). 3. `Zvbb` → `Zvkb` (comment as a superset) This implication was already there but not denoted as a functional superset. This commit adds the comment. 4. `Zvfh` → `Zvfhmin` (comment as a superset) This is similar to the case above (`Zvbb` → `Zvkb`). 5. `Zvfh` → `Zve32f` (add implication per the ISA specification) This dependency is on the ISA manual but was missing (due to the fact that `Zvfh` indirectly implies `Zve32f` on the current implementation through `Zvfh` → `Zvfhmin` which is a functional relation). This commit ensures that this is *also* ISA-compliant in the source code level (there's no functional changes though). 6. `Zvknhb` → `Zvknha` (add as a superset) The `Zvknhb` extension (SHA-256 / SHA-512) is a functional superset of the `Zvknha` extension (SHA-256 only).

Rollup of 23 pull requests Successful merges: - rust-lang#139261 (mitigate MSVC alignment issue on x86-32) - rust-lang#139307 (std: Add performance warnings to HashMap::get_disjoint_mut) - rust-lang#139700 (Autodiff flags) - rust-lang#139752 (set subsections_via_symbols for ld64 helper sections) - rust-lang#139809 (Don't warn about `v128` in wasm ABI transition) - rust-lang#139852 (StableMIR: Implement `CompilerInterface`) - rust-lang#139945 (Extend HIR to track the source and syntax of a lifetime) - rust-lang#140028 (`deref_patterns`: support string and byte string literals in explicit `deref!("...")` patterns) - rust-lang#140139 (rustc_target: Adjust RISC-V feature implication) - rust-lang#140143 (Move `sys::pal::os::Env` into `sys::env`) - rust-lang#140148 (CI: use aws codebuild for job dist-arm-linux) - rust-lang#140150 (fix MAX_EXP and MIN_EXP docs) - rust-lang#140172 (Make algebraic functions into `const fn` items.) - rust-lang#140177 ([compiletest] Parallelize test discovery) - rust-lang#140181 (Remove `synstructure::Structure::underscore_const` calls.) - rust-lang#140184 (Update doc of cygwin target) - rust-lang#140186 (Rename `compute_x` methods) - rust-lang#140187 ([AIX] Handle AIX dynamic library extensions within c-link-to-rust-dylib run-make test) - rust-lang#140191 (Remove git repository from git config) - rust-lang#140194 (minicore: Have `//@ add-core-stubs` also imply `-Cforce-unwind-tables=yes`) - rust-lang#140195 (triagebot: label minicore changes w/ `A-test-infra-minicore` and ping jieyouxu on changes) - rust-lang#140202 (Make #![feature(let_chains)] bootstrap conditional in compiler/) - rust-lang#140214 (Remove comment about handling non-global where bounds with corresponding projection) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#136083 (Suggest {to,from}_ne_bytes for transmutations between arrays and integers, etc) - rust-lang#138282 (Add `#[repr(u128)]`/`#[repr(i128)]` enums to `improper_ctypes_definitions`) - rust-lang#139700 (Autodiff flags) - rust-lang#140139 (rustc_target: Adjust RISC-V feature implication) - rust-lang#140141 (Move zkVM constants into `sys::env_consts`) - rust-lang#140150 (fix MAX_EXP and MIN_EXP docs) - rust-lang#140172 (Make algebraic functions into `const fn` items.) - rust-lang#140191 (Remove git repository from git config) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#140139 - a4lg:riscv-feature-imply-adjust-1, r=Amanieu rustc_target: Adjust RISC-V feature implication This commit adjusts feature implication of the RISC-V ISA for better feature detection from the user perspective. The main rule is: * If the feature `A` is a functional superset of the feature `B` (`A ⊃ B`), `A` is to imply `B`, even if this implication is not on the manual. Such implications (not directly written in the ISA manual) are commented as `A ⊃ B` which means "`A` is a (functional) superset of `B`". 1. `Zbc` → `Zbkc` (add as a superset) The `Zbkc` extension is a subset of the `Zbc` extension (`Zbc` minus `clmulr` instruction). 2. `Zkr` → (nothing) (remove dependency to `Zicsr`) Implication to the `Zicsr` extension is removed because (although nearly harmless), the `Zkr` extension (or the `seed` CSR section) defines its own subset of the `Zicsr` extension (guaranteed to work against the `seed` CSR which needs read/write access). 3. `Zvbb` → `Zvkb` (comment as a superset) This implication was already there but not denoted as a functional superset. This commit adds the comment. 4. `Zvfh` → `Zvfhmin` (comment as a superset) This is similar to the case above (`Zvbb` → `Zvkb`). 5. `Zvfh` → `Zve32f` (add implication per the ISA specification) This dependency is on the ISA manual but was missing (due to the fact that `Zvfh` indirectly implies `Zve32f` on the current implementation through `Zvfh` → `Zvfhmin` which is a functional relation). This commit ensures that this is *also* ISA-compliant in the source code level (there's no functional changes though). 6. `Zvknhb` → `Zvknha` (add as a superset) The `Zvknhb` extension (SHA-256 / SHA-512) is a functional superset of the `Zvknha` extension (SHA-256 only).

…3, r=Amanieu rustc_target: RISC-V: feature addition batch 3 This is the last batch (3 of 3) for RISC-V feature enhancements intended for the version 1.88 cycle. The author's primary criteria are: 1. The extension is ratified and unprivileged one. 2. The extension is in the RVA23U64 profile (to be a baseline of the application-class RISC-V software ecosystem in the near future), either mandatory or optional. 3. Either: 1. To be discoverable through a `riscv_hwprobe` system call on (currently unreleased) Linux 6.15 (as of rc4) or 2. Helps memory/atomics-related operations more efficient and/or more robust. This is based on the specifications: * [The latest ratified ISA Manuals (version 20240411)](https://lf-riscv.atlassian.net/wiki/spaces/HOME/pages/16154769/RISC-V+Technical+Specifications) * [RVA23/RVB23 profiles](https://github.com/riscv/riscv-profiles/releases/tag/rva23-rvb23-ratified) * [RISC-V BF16 extensions](https://github.com/riscv/riscv-bfloat16/releases/tag/v183a3dac863d7c18187a739eb52b0c8f0d16854d) LLVM Definitions: * [`Zicbop`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L82-87) * [`Zicbom`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L75-L80) * [`Zic64b`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L71-L73) * [`Ziccamoa`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L97-L99) * [`Ziccif`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L101-L103) * [`Zicclsm`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L105-L107) * [`Ziccrse`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L109-L111) * [`Zfbfmin`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L320-L325) * [`Zvfbfmin`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L697-L702) * [`Zvfbfwma`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L704-L710) The `Zicbop` extension (mandatory in RVA23U64) adds prefetch hints to prepare for subsequent memory operations (will be executed as no-op if the hardware does not support this extension). The `Zicbom` extension (mandatory in RVA23U64) adds cache block-management instructions. The author did not include this in the batch 2 (because of limited use cases compared to the `Zicboz` extension) but added because it will be discoverable from Linux (as of version 6.15-rc4). Along with `Zicbop`, Rust now supports all CMO extensions. The `Zic64b` extension (mandatory in RVA23U64) constraints the cache block to be naturally-aligned and exactly 64 bytes. Along with CMO instructions, it can improve efficiency handling with memory (e.g. efficient memory zeroing using `Zicboz` + `Zic64b`). The `Zicc*` extensions (mandatory in RVA23U64) add constraints to the main memory properties. They are normally satisfied in the application environment with regular OSes but profiles like RVA23U64 ensures such properties are satisfied (through those *constraint* extensions). The `Zfbf*` and `Zvfbf*` extensions (optional in RVA23U64) add instructions to handle BF16 (BFloat16) data. Although stabilization of FP-related extensions are relatively far due to ABI-related issues, they are included in this batch because they will be discoverable from Linux (as of version 6.15-rc4). The author also adds the extension implication: `Za64rs` → `Za128rs` (superset) which the author missed to include in rust-lang#140139.

Rollup merge of rust-lang#140507 - a4lg:riscv-feature-addition-batch-3, r=Amanieu rustc_target: RISC-V: feature addition batch 3 This is the last batch (3 of 3) for RISC-V feature enhancements intended for the version 1.88 cycle. The author's primary criteria are: 1. The extension is ratified and unprivileged one. 2. The extension is in the RVA23U64 profile (to be a baseline of the application-class RISC-V software ecosystem in the near future), either mandatory or optional. 3. Either: 1. To be discoverable through a `riscv_hwprobe` system call on (currently unreleased) Linux 6.15 (as of rc4) or 2. Helps memory/atomics-related operations more efficient and/or more robust. This is based on the specifications: * [The latest ratified ISA Manuals (version 20240411)](https://lf-riscv.atlassian.net/wiki/spaces/HOME/pages/16154769/RISC-V+Technical+Specifications) * [RVA23/RVB23 profiles](https://github.com/riscv/riscv-profiles/releases/tag/rva23-rvb23-ratified) * [RISC-V BF16 extensions](https://github.com/riscv/riscv-bfloat16/releases/tag/v183a3dac863d7c18187a739eb52b0c8f0d16854d) LLVM Definitions: * [`Zicbop`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L82-87) * [`Zicbom`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L75-L80) * [`Zic64b`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L71-L73) * [`Ziccamoa`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L97-L99) * [`Ziccif`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L101-L103) * [`Zicclsm`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L105-L107) * [`Ziccrse`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L109-L111) * [`Zfbfmin`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L320-L325) * [`Zvfbfmin`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L697-L702) * [`Zvfbfwma`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L704-L710) The `Zicbop` extension (mandatory in RVA23U64) adds prefetch hints to prepare for subsequent memory operations (will be executed as no-op if the hardware does not support this extension). The `Zicbom` extension (mandatory in RVA23U64) adds cache block-management instructions. The author did not include this in the batch 2 (because of limited use cases compared to the `Zicboz` extension) but added because it will be discoverable from Linux (as of version 6.15-rc4). Along with `Zicbop`, Rust now supports all CMO extensions. The `Zic64b` extension (mandatory in RVA23U64) constraints the cache block to be naturally-aligned and exactly 64 bytes. Along with CMO instructions, it can improve efficiency handling with memory (e.g. efficient memory zeroing using `Zicboz` + `Zic64b`). The `Zicc*` extensions (mandatory in RVA23U64) add constraints to the main memory properties. They are normally satisfied in the application environment with regular OSes but profiles like RVA23U64 ensures such properties are satisfied (through those *constraint* extensions). The `Zfbf*` and `Zvfbf*` extensions (optional in RVA23U64) add instructions to handle BF16 (BFloat16) data. Although stabilization of FP-related extensions are relatively far due to ABI-related issues, they are included in this batch because they will be discoverable from Linux (as of version 6.15-rc4). The author also adds the extension implication: `Za64rs` → `Za128rs` (superset) which the author missed to include in rust-lang#140139.

rustbot assigned Amanieu Apr 22, 2025

taiki-e reviewed Apr 23, 2025

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taiki-e approved these changes Apr 23, 2025

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bors 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 23, 2025

Zalathar mentioned this pull request Apr 24, 2025

Rollup of 23 pull requests #140231

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matthiaskrgr mentioned this pull request Apr 24, 2025

Rollup of 8 pull requests #140256

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bors merged commit 31a72bc into rust-lang:master Apr 24, 2025
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rustbot added this to the 1.88.0 milestone Apr 24, 2025

a4lg mentioned this pull request Apr 30, 2025

rustc_target: RISC-V: feature addition batch 3 #140507

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rustc_target: Adjust RISC-V feature implication #140139

rustc_target: Adjust RISC-V feature implication #140139

a4lg commented Apr 22, 2025

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bors commented Apr 23, 2025

rustc_target: Adjust RISC-V feature implication #140139

rustc_target: Adjust RISC-V feature implication #140139

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