rustc_target: RISC-V: feature addition batch 2 #139440
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This commit adds unprivileged ratified extensions that are either
dicoverable from the `riscv_hwprobe` syscall of the Linux kernel (as of
version 6.14) plus 1 minus 3 extensions.
Plus 1:
* "B"
This is a combination of "Zba", "Zbb" and "Zbs".
Note:
Although not required by the RISC-V specification, it is convenient to
imply "B" from its three members (will be implemented in LLVM 21/22) but
this is not yet implemented in Rust due to current implication handling.
It still implies three members *from* "B".
Minus 2:
* "Zcf" (target_arch = "riscv32" only)
This is the compression instruction subset corresponding "F".
This is implied from RV32 + "C" + "F" but this complex handling is
not yet supported by Rust's feature handling.
* "Zcd"
This is the compression instruction subset corresponding "D".
This is implied from "C" + "D" but this complex handling is
not yet supported by Rust's feature handling.
* "Supm"
Unlike regular RISC-V extensions, "Supm" and "Sspm" extensions do not
provide any specific architectural features / constraints but requires
*some* mechanisms to control pointer masking for the current mode.
For instance, reported existence of the "Supm" extension in Linux means
that `prctl` system call to control pointer masking is available and
there are alternative ways to detect the existence.
Notes:
* Because this commit adds the "Zca" extension (an integer subset of the
"C" extension), the "C" extension is modified to imply "Zca".
The "B" extension is ratified as a combination of three extensions: "Zba", "Zbb" and "Zbs". To maximize discoverability of the RISC-V target features, this commit makes use of the "B" extension instead of its three members. This way, `#[cfg(target_feature = "b")]` can also be used instead of: `#[cfg(all(target_feature = "zba", target_feature = "zbb", target_feature = "zbs"))]`
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#135340 (Add `explicit_extern_abis` Feature and Enforce Explicit ABIs) - rust-lang#139440 (rustc_target: RISC-V: feature addition batch 2) - rust-lang#139667 (cfi: Remove #[no_sanitize(cfi)] for extern weak functions) - rust-lang#139828 (Don't require rigid alias's trait to hold) - rust-lang#139854 (Improve parse errors for stray lifetimes in type position) - rust-lang#139889 (Clean UI tests 3 of n) - rust-lang#139894 (Fix `opt-dist` CLI flag and make it work without LLD) - rust-lang#139900 (stepping into impls for normalization is unproductive) - rust-lang#139915 (replace some #[rustc_intrinsic] usage with use of the libcore declarations) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#139440 - a4lg:riscv-feature-addition-batch-2, r=Amanieu rustc_target: RISC-V: feature addition batch 2 Of ratified RISC-V extensions, this commit adds ones satisfying following criteria: 1. Either discoverable through a `riscv_hwprobe` system call on Linux 6.14 or should be very helpful even on basic needs (the `B` extension), 2. Does not disrupt current Rust's feature handling mechanism and 3. Not too OS-dependent (the `Supm` extension) Due to 2., the author excluded `Zcf` (RV32 only) and `Zcd` from the list despite that they are discoverable from Linux 6.14. Due to 3., the author excluded the `Supm` extension on the PR version 2. This is based on the specification: * [The latest ratified ISA Manuals (version 20240411)](https://lf-riscv.atlassian.net/wiki/spaces/HOME/pages/16154769/RISC-V+Technical+Specifications) Linux Definition: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/riscv/include/uapi/asm/hwprobe.h LLVM Definitions: * [`B`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L507-L510) * [`Zca`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L395-L398) * [`Zcb`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L407-L410) * [`Zcmop`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L460-L463) * [`Zfa`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L335-L338) * [`Zicboz`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L89-L92) * [`Zicond`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L125-L128) * [`Zihintntl`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L148-L151) * [`Zimop`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L161-L162) * [`Ztso`](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/RISCV/RISCVFeatures.td#L214-L217) The author also adds required implication: `C` implies `Zca`. Android RISC-V target is also updated to include the `B` extension (this is just a shorthand combination of `Zba`, `Zbb` and `Zbs` extensions but possibly simplifies `target_feature` handling). # History ## Version 1 → 2 * Remove the `Supm` extension from the Rust target features (thanks, `@Amanieu).` -------- Related: * rust-lang#44839 (`riscv_target_feature`) * rust-lang#138823 (my previous batch) * rust-lang#132618 (stabilization of the `Zfa` extension is blocked by this) `@rustbot` r? `@Amanieu` `@rustbot` label +T-compiler +O-riscv +A-target-feature
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Of ratified RISC-V extensions, this commit adds ones satisfying following criteria:
riscv_hwprobesystem call on Linux 6.14or should be very helpful even on basic needs (the
Bextension),Supmextension)Due to 2., the author excluded
Zcf(RV32 only) andZcdfrom the list despite that they are discoverable from Linux 6.14.Due to 3., the author excluded the
Supmextension on the PR version 2.This is based on the specification:
Linux Definition: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/riscv/include/uapi/asm/hwprobe.h
LLVM Definitions:
BZcaZcbZcmopZfaZicbozZicondZihintntlZimopZtsoThe author also adds required implication:
CimpliesZca.Android RISC-V target is also updated to include the
Bextension (this is just a shorthand combination ofZba,ZbbandZbsextensions but possibly simplifiestarget_featurehandling).History
Version 1 → 2
Supmextension from the Rust target features (thanks, @Amanieu).Related:
#[target_feature]#44839(
riscv_target_feature)I-related important extensions #138823(my previous batch)
-Ctarget-features must be restrained on RISCV #132618(stabilization of the
Zfaextension is blocked by this)@rustbot r? @Amanieu
@rustbot label +T-compiler +O-riscv +A-target-feature