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add dedicated type for ABI target feature constraints

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This commit is contained in:
Ralf Jung 2025-01-05 10:34:33 +01:00
parent 43ede97ebf
commit 2e64b5352b
5 changed files with 45 additions and 31 deletions
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19
compiler/rustc_codegen_gcc/src/gcc_util.rs
View file

@ -47,9 +47,9 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
// Ensure that all ABI-required features are enabled, and the ABI-forbidden ones
// are disabled.
let (abi_enable, abi_disable) = sess.target.abi_required_features();
let abi_enable_set = FxHashSet::from_iter(abi_enable.iter().copied());
let abi_disable_set = FxHashSet::from_iter(abi_disable.iter().copied());
let abi_feature_constraints = sess.target.abi_required_features();
let abi_incompatible_set =
FxHashSet::from_iter(abi_feature_constraints.incompatible.iter().copied());
// Compute implied features
let mut all_rust_features = vec![];
@ -72,7 +72,7 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
}
}
}
// Remove features that are meant for rustc, not LLVM.
// Remove features that are meant for rustc, not codegen.
all_rust_features.retain(|(_, feature)| {
// Retain if it is not a rustc feature
!RUSTC_SPECIFIC_FEATURES.contains(feature)
@ -121,7 +121,7 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
// Ensure that the features we enable/disable are compatible with the ABI.
if enable {
if abi_disable_set.contains(feature) {
if abi_incompatible_set.contains(feature) {
sess.dcx().emit_warn(ForbiddenCTargetFeature {
feature,
enabled: "enabled",
@ -131,8 +131,7 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
} else {
// FIXME: we have to request implied features here since
// negative features do not handle implied features above.
#[allow(rustc::potential_query_instability)] // order does not matter
for &required in abi_enable_set.iter() {
for &required in abi_feature_constraints.required.iter() {
let implied = sess.target.implied_target_features(std::iter::once(required));
if implied.contains(feature) {
sess.dcx().emit_warn(ForbiddenCTargetFeature {
@ -158,7 +157,11 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
// still override it... that's unsound, but more compatible with past behavior.
all_rust_features.splice(
0..0,
abi_enable.iter().map(|&f| (true, f)).chain(abi_disable.iter().map(|&f| (false, f))),
abi_feature_constraints
.required
.iter()
.map(|&f| (true, f))
.chain(abi_feature_constraints.incompatible.iter().map(|&f| (false, f))),
);
// Translate this into GCC features.

17
compiler/rustc_codegen_llvm/src/llvm_util.rs
View file

@ -669,9 +669,9 @@ pub(crate) fn global_llvm_features(
// Ensure that all ABI-required features are enabled, and the ABI-forbidden ones
// are disabled.
let (abi_enable, abi_disable) = sess.target.abi_required_features();
let abi_enable_set = FxHashSet::from_iter(abi_enable.iter().copied());
let abi_disable_set = FxHashSet::from_iter(abi_disable.iter().copied());
let abi_feature_constraints = sess.target.abi_required_features();
let abi_incompatible_set =
FxHashSet::from_iter(abi_feature_constraints.incompatible.iter().copied());
// Compute implied features
let mut all_rust_features = vec![];
@ -745,7 +745,7 @@ pub(crate) fn global_llvm_features(
// Ensure that the features we enable/disable are compatible with the ABI.
if enable {
if abi_disable_set.contains(feature) {
if abi_incompatible_set.contains(feature) {
sess.dcx().emit_warn(ForbiddenCTargetFeature {
feature,
enabled: "enabled",
@ -755,8 +755,7 @@ pub(crate) fn global_llvm_features(
} else {
// FIXME: we have to request implied features here since
// negative features do not handle implied features above.
#[allow(rustc::potential_query_instability)] // order does not matter
for &required in abi_enable_set.iter() {
for &required in abi_feature_constraints.required.iter() {
let implied =
sess.target.implied_target_features(std::iter::once(required));
if implied.contains(feature) {
@ -783,7 +782,11 @@ pub(crate) fn global_llvm_features(
// still override it... that's unsound, but more compatible with past behavior.
all_rust_features.splice(
0..0,
abi_enable.iter().map(|&f| (true, f)).chain(abi_disable.iter().map(|&f| (false, f))),
abi_feature_constraints
.required
.iter()
.map(|&f| (true, f))
.chain(abi_feature_constraints.incompatible.iter().map(|&f| (false, f))),
);
// Translate this into LLVM features.

4
compiler/rustc_codegen_ssa/src/target_features.rs
View file

@ -32,7 +32,7 @@ pub(crate) fn from_target_feature_attr(
.emit();
};
let rust_features = tcx.features();
let (_abi_enable, abi_disable) = tcx.sess.target.abi_required_features();
let abi_feature_constraints = tcx.sess.target.abi_required_features();
for item in list {
// Only `enable = ...` is accepted in the meta-item list.
if !item.has_name(sym::enable) {
@ -87,7 +87,7 @@ pub(crate) fn from_target_feature_attr(
// But ensure the ABI does not forbid enabling this.
// Here we do assume that LLVM doesn't add even more implied features
// we don't know about, at least no features that would have ABI effects!
if abi_disable.contains(&name.as_str()) {
if abi_feature_constraints.incompatible.contains(&name.as_str()) {
tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
span: item.span(),
feature: name.as_str(),

8
compiler/rustc_target/src/spec/mod.rs
View file

@ -3242,8 +3242,8 @@ impl Target {
}
}
// Check that we don't mis-set any of the ABI-relevant features.
let (abi_enable, abi_disable) = self.abi_required_features();
for feat in abi_enable {
let abi_feature_constraints = self.abi_required_features();
for feat in abi_feature_constraints.required {
// The feature might be enabled by default so we can't *require* it to show up.
// But it must not be *disabled*.
if features_disabled.contains(feat) {
@ -3252,8 +3252,8 @@ impl Target {
));
}
}
for feat in abi_disable {
// The feature might be disable by default so we can't *require* it to show up.
for feat in abi_feature_constraints.incompatible {
// The feature might be disabled by default so we can't *require* it to show up.
// But it must not be *enabled*.
if features_enabled.contains(feat) {
return Err(format!(

28
compiler/rustc_target/src/target_features.rs
View file

@ -669,6 +669,14 @@ const CSKY_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(
const LOONGARCH_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
&[(128, "lsx"), (256, "lasx")];
#[derive(Copy, Clone, Debug)]
pub struct FeatureConstraints {
/// Features that must be enabled.
pub required: &'static [&'static str],
/// Features that must be disabled.
pub incompatible: &'static [&'static str],
}
impl Target {
pub fn rust_target_features(&self) -> &'static [(&'static str, Stability, ImpliedFeatures)] {
match &*self.arch {
@ -749,8 +757,8 @@ impl Target {
/// All features enabled/disabled via `-Ctarget-features` and `#[target_features]` are checked
/// against this. We also check any implied features, based on the information above. If LLVM
/// implicitly enables more implied features than we do, that could bypass this check!
pub fn abi_required_features(&self) -> (&'static [&'static str], &'static [&'static str]) {
const NOTHING: (&'static [&'static str], &'static [&'static str]) = (&[], &[]);
pub fn abi_required_features(&self) -> FeatureConstraints {
const NOTHING: FeatureConstraints = FeatureConstraints { required: &[], incompatible: &[] };
// Some architectures don't have a clean explicit ABI designation; instead, the ABI is
// defined by target features. When that is the case, those target features must be
// "forbidden" in the list above to ensure that there is a consistent answer to the
@ -763,7 +771,7 @@ impl Target {
NOTHING
} else {
// Hardfloat ABI. x87 must be enabled.
(&["x87"], &[])
FeatureConstraints { required: &["x87"], incompatible: &[] }
}
}
"x86_64" => {
@ -773,7 +781,7 @@ impl Target {
NOTHING
} else {
// Hardfloat ABI. x87 and SSE2 must be enabled.
(&["x87", "sse2"], &[])
FeatureConstraints { required: &["x87", "sse2"], incompatible: &[] }
}
}
"arm" => {
@ -786,7 +794,7 @@ impl Target {
}
FloatAbi::Hard => {
// Must have `fpregs` and must not have `soft-float`.
(&["fpregs"], &["soft-float"])
FeatureConstraints { required: &["fpregs"], incompatible: &["soft-float"] }
}
}
}
@ -803,7 +811,7 @@ impl Target {
_ => {
// Everything else is assumed to use a hardfloat ABI. neon and fp-armv8 must be enabled.
// These are Rust feature names and we use "neon" to control both of them.
(&["neon"], &[])
FeatureConstraints { required: &["neon"], incompatible: &[] }
}
}
}
@ -813,15 +821,15 @@ impl Target {
match &*self.llvm_abiname {
"ilp32d" | "lp64d" => {
// Requires d (which implies f), incompatible with e.
(&["d"], &["e"])
FeatureConstraints { required: &["d"], incompatible: &["e"] }
}
"ilp32f" | "lp64f" => {
// Requires f, incompatible with e.
(&["f"], &["e"])
FeatureConstraints { required: &["f"], incompatible: &["e"] }
}
"ilp32" | "lp64" => {
// Requires nothing, incompatible with e.
(&[], &["e"])
FeatureConstraints { required: &[], incompatible: &["e"] }
}
"ilp32e" => {
// ilp32e is documented to be incompatible with features that need aligned
@ -832,7 +840,7 @@ impl Target {
// Note that the `e` feature is not required: the ABI treats the extra
// registers as caller-save, so it is safe to use them only in some parts of
// a program while the rest doesn't know they even exist.
(&[], &["d"])
FeatureConstraints { required: &[], incompatible: &["d"] }
}
"lp64e" => {
// As above, `e` is not required.