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std_detect: RISC-V: Best effort implication of target features by custom cfg #145810

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std_detect: RISC-V: Best effort implication of target features by custom cfg #145810

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55a08bc
std_detect: Tidying for preparation of adding `@FEATURE` options
a4lg Aug 24, 2025
09dc987
std_detect: Add implication from custom `cfg`
a4lg Aug 24, 2025
f4e9808
std_detect: RISC-V: Best effort implication by target config (group)
a4lg Aug 24, 2025
61c6b10
std_detect: RISC-V: Best effort implication by target config (C-related)
a4lg Aug 24, 2025
74851f7
std_detect: AArch64: Use `implied by cfg(...)`
a4lg Aug 24, 2025
99d68f3
std_detect: Remove support for `implied by target_features`
a4lg Aug 24, 2025
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4 changes: 2 additions & 2 deletions library/std_detect/src/detect/arch/aarch64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -110,10 +110,10 @@ features! {
@FEATURE: #[stable(feature = "simd_aarch64", since = "1.60.0")] asimd: "neon";
/// FEAT_AdvSIMD (Advanced SIMD/NEON)
@FEATURE: #[stable(feature = "simd_aarch64", since = "1.60.0")] pmull: "pmull";
implied by target_features: ["aes"];
implied by cfg(target_feature = "aes");
/// FEAT_PMULL (Polynomial Multiply) - Implied by `aes` target_feature
@FEATURE: #[stable(feature = "simd_aarch64", since = "1.60.0")] fp: "fp";
implied by target_features: ["neon"];
implied by cfg(target_feature = "neon");
/// FEAT_FP (Floating point support) - Implied by `neon` target_feature
@FEATURE: #[stable(feature = "simd_aarch64", since = "1.60.0")] aes: "aes";
/// FEAT_AES (AES SIMD instructions) & FEAT_PMULL (PMULL{2}, 64-bit operand variants)
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119 changes: 117 additions & 2 deletions library/std_detect/src/detect/arch/riscv.rs
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Expand Up @@ -220,6 +220,13 @@ features! {
/// "M" Extension for Integer Multiplication and Division

@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] a: "a";
implied by cfg(any(
target_feature = "a",
all(
target_feature = "zalrsc",
target_feature = "zaamo",
)
));
/// "A" Extension for Atomic Instructions
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zalrsc: "zalrsc";
/// "Zalrsc" Extension for Load-Reserved/Store-Conditional Instructions
Expand Down Expand Up @@ -263,21 +270,37 @@ features! {
/// "Zhinxmin" Extension for Minimal Half-Precision Floating-Point in Integer Registers

@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] c: "c";
implied by cfg(any(
target_feature = "c",
all(
not(target_feature = "d"),
any(not(target_arch = "riscv32"), not(target_feature = "f")),
target_feature = "zca",
)
));
/// "C" Extension for Compressed Instructions
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zca: "zca";
/// "Zca" Compressed Instructions excluding Floating-Point Loads/Stores
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zcf: "zcf";
without cfg check: true;
implied by cfg(all(target_arch = "riscv32", target_feature = "c", target_feature = "f"));
/// "Zcf" Compressed Instructions for Single-Precision Floating-Point Loads/Stores on RV32
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zcd: "zcd";
without cfg check: true;
implied by cfg(all(target_feature = "c", target_feature = "d"));
/// "Zcd" Compressed Instructions for Double-Precision Floating-Point Loads/Stores
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zcb: "zcb";
/// "Zcb" Simple Code-size Saving Compressed Instructions
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zcmop: "zcmop";
/// "Zcmop" Extension for Compressed May-Be-Operations

@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] b: "b";
implied by cfg(any(
target_feature = "b",
all(
target_feature = "zba",
target_feature = "zbb",
target_feature = "zbs",
)
));
/// "B" Extension for Bit Manipulation
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zba: "zba";
/// "Zba" Extension for Address Generation
Expand Down Expand Up @@ -307,10 +330,44 @@ features! {
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zkr: "zkr";
/// "Zkr" Entropy Source Extension
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zkn: "zkn";
implied by cfg(any(
target_feature = "zkn",
all(
target_feature = "zbkb",
target_feature = "zbkc",
target_feature = "zbkx",
target_feature = "zkne",
target_feature = "zknd",
target_feature = "zknh",
)
));
/// "Zkn" Cryptography Extension for NIST Algorithm Suite
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zks: "zks";
implied by cfg(any(
target_feature = "zks",
all(
target_feature = "zbkb",
target_feature = "zbkc",
target_feature = "zbkx",
target_feature = "zksed",
target_feature = "zksh",
)
));
/// "Zks" Cryptography Extension for ShangMi Algorithm Suite
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zk: "zk";
implied by cfg(any(
target_feature = "zk",
all(
target_feature = "zbkb",
target_feature = "zbkc",
target_feature = "zbkx",
target_feature = "zkne",
target_feature = "zknd",
target_feature = "zknh",
target_feature = "zkr",
target_feature = "zkt",
)
));
/// "Zk" Cryptography Extension for Standard Scalar Cryptography
@FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] zkt: "zkt";
/// "Zkt" Cryptography Extension for Data Independent Execution Latency
Expand Down Expand Up @@ -355,16 +412,74 @@ features! {
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvksh: "zvksh";
/// "Zvksh" Cryptography Extension for ShangMi Suite: Vector SM3 Secure Hash
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvkn: "zvkn";
implied by cfg(any(
target_feature = "zvkn",
all(
target_feature = "zvkned",
target_feature = "zvknhb",
target_feature = "zvkb",
target_feature = "zvkt",
)
));
/// "Zvkn" Cryptography Extension for NIST Algorithm Suite
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvknc: "zvknc";
implied by cfg(any(
target_feature = "zvknc",
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@Amanieu Amanieu Sep 11, 2025

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This line seems redundant and could be folded into the macro itself: a feature is always implied by itself.

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@a4lg a4lg Sep 17, 2025 •
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... unless implied by is used (even implied by target_features:, which is to be removed in this PR suppresses self implication; see the macro expansion carefully).
So, zvknc runtime (std_detect) target feature is not directly implied by zvknc compiler target feature itself.

Still, you are technically right since... for instance (in this place), zvknc is just a collection of sub-extensions (zvkned, zvknhb...) and zvknc compiler target feature directly/indirectly enables all of them (indirectly enabling runtime target feature zvknc).
The reason I keep zvknc itself is to check validity of the compiler target feature (through check_cfg_feature!).

I think we can keep this (and similar lines) as-is (in this PR).

all(
target_feature = "zvkned",
target_feature = "zvknhb",
target_feature = "zvkb",
target_feature = "zvkt",
target_feature = "zvbc",
)
));
/// "Zvknc" Cryptography Extension for NIST Algorithm Suite with Carryless Multiply
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvkng: "zvkng";
implied by cfg(any(
target_feature = "zvkng",
all(
target_feature = "zvkned",
target_feature = "zvknhb",
target_feature = "zvkb",
target_feature = "zvkt",
target_feature = "zvkg",
)
));
/// "Zvkng" Cryptography Extension for NIST Algorithm Suite with GCM
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvks: "zvks";
implied by cfg(any(
target_feature = "zvks",
all(
target_feature = "zvksed",
target_feature = "zvksh",
target_feature = "zvkb",
target_feature = "zvkt",
)
));
/// "Zvks" Cryptography Extension for ShangMi Algorithm Suite
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvksc: "zvksc";
implied by cfg(any(
target_feature = "zvksc",
all(
target_feature = "zvksed",
target_feature = "zvksh",
target_feature = "zvkb",
target_feature = "zvkt",
target_feature = "zvbc",
)
));
/// "Zvksc" Cryptography Extension for ShangMi Algorithm Suite with Carryless Multiply
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvksg: "zvksg";
implied by cfg(any(
target_feature = "zvksg",
all(
target_feature = "zvksed",
target_feature = "zvksh",
target_feature = "zvkb",
target_feature = "zvkt",
target_feature = "zvkg",
)
));
/// "Zvksg" Cryptography Extension for ShangMi Algorithm Suite with GCM
@FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zvkt: "zvkt";
/// "Zvkt" Extension for Vector Data-Independent Execution Latency
Expand Down
33 changes: 22 additions & 11 deletions library/std_detect/src/detect/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,10 @@
#[unstable(feature = "stdarch_internal", issue = "none")]
macro_rules! detect_feature {
($feature:tt, $feature_lit:tt) => {
$crate::detect_feature!($feature, $feature_lit : $feature_lit)
cfg!(target_feature = $feature_lit) || $crate::detect::__is_feature_detected::$feature()
};
($feature:tt, $feature_lit:tt : $($target_feature_lit:tt),*) => {
$(cfg!(target_feature = $target_feature_lit) ||)*
$crate::detect::__is_feature_detected::$feature()
($feature:tt, $feature_lit:tt : cfg($target_feature_cfg:meta)) => {
cfg!($target_feature_cfg) || $crate::detect::__is_feature_detected::$feature()
};
($feature:tt, $feature_lit:tt, without cfg check: true) => {
$crate::detect::__is_feature_detected::$feature()
Expand All @@ -17,14 +16,16 @@ macro_rules! detect_feature {
#[allow(unused_macros, reason = "it's used in the features! macro below")]
macro_rules! check_cfg_feature {
($feature:tt, $feature_lit:tt) => {
check_cfg_feature!($feature, $feature_lit : $feature_lit)
cfg!(target_feature = $feature_lit);
};
($feature:tt, $feature_lit:tt : $($target_feature_lit:tt),*) => {
$(cfg!(target_feature = $target_feature_lit);)*
($feature:tt, $feature_lit:tt : cfg($target_feature_cfg:meta)) => {
cfg!($target_feature_cfg);
};
($feature:tt, $feature_lit:tt, without cfg check: $feature_cfg_check:literal) => {
#[allow(unexpected_cfgs, reason = $feature_lit)]
{ cfg!(target_feature = $feature_lit) }
{
cfg!(target_feature = $feature_lit)
}
};
}

Expand All @@ -39,7 +40,7 @@ macro_rules! features {
$(@NO_RUNTIME_DETECTION: $nort_feature:tt; )*
$(@FEATURE: #[$stability_attr:meta] $feature:ident: $feature_lit:tt;
$(without cfg check: $feature_cfg_check:tt;)?
$(implied by target_features: [$($target_feature_lit:tt),*];)?
$(implied by cfg($target_feature_cfg:meta);)?
$(#[$feature_comment:meta])*)*
) => {
#[macro_export]
Expand All @@ -50,7 +51,12 @@ macro_rules! features {
macro_rules! $macro_name {
$(
($feature_lit) => {
$crate::detect_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?)
$crate::detect_feature!(
$feature,
$feature_lit
$(, without cfg check: $feature_cfg_check)?
$(: cfg($target_feature_cfg))?
)
};
)*
$(
Expand Down Expand Up @@ -135,7 +141,12 @@ macro_rules! features {
#[deny(unfulfilled_lint_expectations)]
const _: () = {
$(
check_cfg_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?);
check_cfg_feature!(
$feature,
$feature_lit
$(, without cfg check: $feature_cfg_check)?
$(: cfg($target_feature_cfg))?
);
)*
};

Expand Down
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