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Don't use LLVM to compute -Ctarget-feature

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This commit is contained in:
Caleb Zulawski 2024-08-03 23:51:37 -04:00
parent 484aca8857
commit a25da077cf
6 changed files with 121 additions and 113 deletions
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213
compiler/rustc_codegen_llvm/src/llvm_util.rs
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@ -308,19 +308,10 @@ pub fn check_tied_features(
/// Used to generate cfg variables and apply features
/// Must express features in the way Rust understands them
pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
let rust_features = sess
.target
.supported_target_features()
.iter()
.map(|(feature, _, _)| {
(to_llvm_features(sess, feature).llvm_feature_name, Symbol::intern(feature))
})
.collect::<FxHashMap<_, _>>();
let mut features = FxHashSet::default();
// Add base features for the target
let target_machine = create_informational_target_machine(sess, false);
let target_machine = create_informational_target_machine(sess, true);
features.extend(
sess.target
.supported_target_features()
@ -343,13 +334,16 @@ pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
);
// Add enabled features
for llvm_feature in global_llvm_features(sess, false) {
let (add, llvm_feature) = llvm_feature.split_at(1);
let feature =
rust_features.get(llvm_feature).cloned().unwrap_or(Symbol::intern(llvm_feature));
if add == "+" {
for (enabled, feature) in
sess.opts.cg.target_feature.split(',').filter_map(|s| match s.chars().next() {
Some('+') => Some((true, Symbol::intern(&s[1..]))),
Some('-') => Some((false, Symbol::intern(&s[1..]))),
_ => None,
})
{
if enabled {
features.extend(sess.target.implied_target_features(std::iter::once(feature)));
} else if add == "-" {
} else {
features.remove(&feature);
}
}
@ -475,7 +469,7 @@ fn print_target_features(out: &mut String, sess: &Session, tm: &llvm::TargetMach
pub(crate) fn print(req: &PrintRequest, mut out: &mut String, sess: &Session) {
require_inited();
let tm = create_informational_target_machine(sess, true);
let tm = create_informational_target_machine(sess, false);
match req.kind {
PrintKind::TargetCPUs => {
// SAFETY generate a C compatible string from a byte slice to pass
@ -523,7 +517,11 @@ pub fn target_cpu(sess: &Session) -> &str {
/// The list of LLVM features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`,
/// `--target` and similar).
pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<String> {
pub(crate) fn global_llvm_features(
sess: &Session,
diagnostics: bool,
only_base_features: bool,
) -> Vec<String> {
// Features that come earlier are overridden by conflicting features later in the string.
// Typically we'll want more explicit settings to override the implicit ones, so:
//
@ -583,96 +581,109 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
}
// -Ctarget-features
let supported_features = sess.target.supported_target_features();
let (llvm_major, _, _) = get_version();
let mut featsmap = FxHashMap::default();
let feats = sess
.opts
.cg
.target_feature
.split(',')
.filter_map(|s| {
let enable_disable = match s.chars().next() {
None => return None,
Some(c @ ('+' | '-')) => c,
Some(_) => {
if diagnostics {
sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature: s });
if !only_base_features {
let supported_features = sess.target.supported_target_features();
let (llvm_major, _, _) = get_version();
let mut featsmap = FxHashMap::default();
let feats = sess
.opts
.cg
.target_feature
.split(',')
.filter_map(|s| {
let enable_disable = match s.chars().next() {
None => return None,
Some(c @ ('+' | '-')) => c,
Some(_) => {
if diagnostics {
sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature: s });
}
return None;
}
};
let feature = backend_feature_name(sess, s)?;
// Warn against use of LLVM specific feature names and unstable features on the CLI.
if diagnostics {
let feature_state = supported_features.iter().find(|&&(v, _, _)| v == feature);
if feature_state.is_none() {
let rust_feature =
supported_features.iter().find_map(|&(rust_feature, _, _)| {
let llvm_features = to_llvm_features(sess, rust_feature);
if llvm_features.contains(feature)
&& !llvm_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);
} else if feature_state
.is_some_and(|(_name, feature_gate, _implied)| !feature_gate.is_stable())
{
// An unstable feature. Warn about using it.
sess.dcx().emit_warn(UnstableCTargetFeature { feature });
}
}
if diagnostics {
// 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 LLVM…
if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
return None;
}
};
let feature = backend_feature_name(sess, s)?;
// Warn against use of LLVM specific feature names and unstable features on the CLI.
if diagnostics {
let feature_state = supported_features.iter().find(|&&(v, _, _)| v == feature);
if feature_state.is_none() {
let rust_feature =
supported_features.iter().find_map(|&(rust_feature, _, _)| {
let llvm_features = to_llvm_features(sess, rust_feature);
if llvm_features.contains(feature)
&& !llvm_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);
} else if feature_state
.is_some_and(|(_name, feature_gate, _implied)| !feature_gate.is_stable())
{
// An unstable feature. Warn about using it.
sess.dcx().emit_warn(UnstableCTargetFeature { feature });
// if the target-feature is "backchain" and LLVM version is greater than 18
// then we also need to add "+backchain" to the target-features attribute.
// otherwise, we will only add the naked `backchain` attribute to the attribute-group.
if feature == "backchain" && llvm_major < 18 {
return None;
}
}
// ... otherwise though we run through `to_llvm_features` when
// passing requests down to LLVM. This means that all in-language
// features also work on the command line instead of having two
// different names when the LLVM name and the Rust name differ.
let llvm_feature = to_llvm_features(sess, feature);
if diagnostics {
// 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 LLVM…
if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
return None;
}
// if the target-feature is "backchain" and LLVM version is greater than 18
// then we also need to add "+backchain" to the target-features attribute.
// otherwise, we will only add the naked `backchain` attribute to the attribute-group.
if feature == "backchain" && llvm_major < 18 {
return None;
}
// ... otherwise though we run through `to_llvm_features` when
// passing requests down to LLVM. This means that all in-language
// features also work on the command line instead of having two
// different names when the LLVM name and the Rust name differ.
let llvm_feature = to_llvm_features(sess, feature);
Some(
std::iter::once(format!("{}{}", enable_disable, llvm_feature.llvm_feature_name))
.chain(llvm_feature.dependency.into_iter().filter_map(move |feat| {
match (enable_disable, feat) {
Some(
std::iter::once(format!(
"{}{}",
enable_disable, llvm_feature.llvm_feature_name
))
.chain(llvm_feature.dependency.into_iter().filter_map(
move |feat| match (enable_disable, feat) {
('-' | '+', TargetFeatureFoldStrength::Both(f))
| ('+', TargetFeatureFoldStrength::EnableOnly(f)) => {
Some(format!("{enable_disable}{f}"))
}
_ => None,
}
})),
)
})
.flatten();
features.extend(feats);
},
)),
)
})
.flatten();
features.extend(feats);
if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
sess.dcx().emit_err(TargetFeatureDisableOrEnable {
features: f,
span: None,
missing_features: None,
});
}
}
// -Zfixed-x18
if sess.opts.unstable_opts.fixed_x18 {
@ -683,14 +694,6 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
}
}
if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
sess.dcx().emit_err(TargetFeatureDisableOrEnable {
features: f,
span: None,
missing_features: None,
});
}
features
}