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mark some target features as 'forbidden' so they cannot be (un)set

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For now, this is just a warning, but should become a hard error in the future
This commit is contained in:
Ralf Jung
2024-09-02 11:45:59 +02:00
parent 2dece5bb62
commit ffad9aac27
23 changed files with 372 additions and 158 deletions
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69
compiler/rustc_codegen_gcc/src/gcc_util.rs
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@@ -5,10 +5,13 @@ use rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable;
use rustc_data_structures::fx::FxHashMap;
use rustc_middle::bug;
use rustc_session::Session;
use rustc_target::target_features::RUSTC_SPECIFIC_FEATURES;
use rustc_target::target_features::{RUSTC_SPECIFIC_FEATURES, Stability};
use smallvec::{SmallVec, smallvec};
use crate::errors::{PossibleFeature, UnknownCTargetFeature, UnknownCTargetFeaturePrefix};
use crate::errors::{
ForbiddenCTargetFeature, PossibleFeature, UnknownCTargetFeature, UnknownCTargetFeaturePrefix,
UnstableCTargetFeature,
};
/// The list of GCC features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`,
/// `--target` and similar).
@@ -43,7 +46,7 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
);
// -Ctarget-features
let supported_features = sess.target.supported_target_features();
let known_features = sess.target.rust_target_features();
let mut featsmap = FxHashMap::default();
let feats = sess
.opts
@@ -62,37 +65,49 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
}
};
// Get the backend feature name, if any.
// This excludes rustc-specific features, that do not get passed down to GCC.
let feature = backend_feature_name(s)?;
// Warn against use of GCC specific feature names on the CLI.
if diagnostics && !supported_features.iter().any(|&(v, _, _)| v == feature) {
let rust_feature = supported_features.iter().find_map(|&(rust_feature, _, _)| {
let gcc_features = to_gcc_features(sess, rust_feature);
if gcc_features.contains(&feature) && !gcc_features.contains(&rust_feature) {
Some(rust_feature)
} else {
None
}
});
let unknown_feature = if let Some(rust_feature) = rust_feature {
UnknownCTargetFeature {
feature,
rust_feature: PossibleFeature::Some { rust_feature },
}
} else {
UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
};
sess.dcx().emit_warn(unknown_feature);
}
if diagnostics {
let feature_state = known_features.iter().find(|&&(v, _, _)| v == feature);
match feature_state {
None => {
let rust_feature =
known_features.iter().find_map(|&(rust_feature, _, _)| {
let gcc_features = to_gcc_features(sess, rust_feature);
if gcc_features.contains(&feature)
&& !gcc_features.contains(&rust_feature)
{
Some(rust_feature)
} else {
None
}
});
let unknown_feature = if let Some(rust_feature) = rust_feature {
UnknownCTargetFeature {
feature,
rust_feature: PossibleFeature::Some { rust_feature },
}
} else {
UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
};
sess.dcx().emit_warn(unknown_feature);
}
Some((_, Stability::Stable, _)) => {}
Some((_, Stability::Unstable(_), _)) => {
// An unstable feature. Warn about using it.
sess.dcx().emit_warn(UnstableCTargetFeature { feature });
}
Some((_, Stability::Forbidden { .. }, _)) => {
sess.dcx().emit_err(ForbiddenCTargetFeature { feature });
}
}
// FIXME(nagisa): figure out how to not allocate a full hashset here.
featsmap.insert(feature, enable_disable == '+');
}
// rustc-specific features do not get passed down to GCC…
if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
return None;
}
// ... otherwise though we run through `to_gcc_features` when
// passing requests down to GCC. This means that all in-language
// features also work on the command line instead of having two