adjust GCC backend
This commit is contained in:
Ralf Jung
parent
cfae43d638
commit
0a8cfc2f8f
2 changed files with 117 additions and 82 deletions
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@ -28,6 +28,7 @@ pub(crate) struct UnstableCTargetFeature<'a> {
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#[diag(codegen_gcc_forbidden_ctarget_feature)]
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pub(crate) struct ForbiddenCTargetFeature<'a> {
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pub feature: &'a str,
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pub enabled: &'a str,
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pub reason: &'a str,
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}
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@ -1,9 +1,11 @@
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use std::iter::FromIterator;
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#[cfg(feature = "master")]
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use gccjit::Context;
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use rustc_codegen_ssa::codegen_attrs::check_tied_features;
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use rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_middle::bug;
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_data_structures::unord::UnordSet;
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use rustc_session::Session;
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use rustc_target::target_features::RUSTC_SPECIFIC_FEATURES;
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use smallvec::{SmallVec, smallvec};
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@ -37,82 +39,128 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
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let mut features = vec![];
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// Features implied by an implicit or explicit `--target`.
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features.extend(
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sess.target
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.features
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.split(',')
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.filter(|v| !v.is_empty() && backend_feature_name(v).is_some())
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.map(String::from),
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);
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features.extend(sess.target.features.split(',').filter(|v| !v.is_empty()).map(String::from));
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// -Ctarget-features
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let known_features = sess.target.rust_target_features();
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let mut featsmap = FxHashMap::default();
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let feats = sess
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.opts
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.cg
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.target_feature
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.split(',')
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.filter_map(|s| {
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let enable_disable = match s.chars().next() {
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None => return None,
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Some(c @ ('+' | '-')) => c,
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Some(_) => {
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if diagnostics {
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sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature: s });
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}
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return None;
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}
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};
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// Get the backend feature name, if any.
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// This excludes rustc-specific features, that do not get passed down to GCC.
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let feature = backend_feature_name(s)?;
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// Warn against use of GCC specific feature names on the CLI.
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// Ensure that all ABI-required features are enabled, and the ABI-forbidden ones
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// are disabled.
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let (abi_enable, abi_disable) = sess.target.abi_required_features();
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let abi_enable_set = FxHashSet::from_iter(abi_enable.iter().copied());
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let abi_disable_set = FxHashSet::from_iter(abi_disable.iter().copied());
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// Compute implied features
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let mut all_rust_features = vec![];
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for feature in sess.opts.cg.target_feature.split(',') {
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if let Some(feature) = feature.strip_prefix('+') {
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all_rust_features.extend(
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UnordSet::from(sess.target.implied_target_features(std::iter::once(feature)))
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.to_sorted_stable_ord()
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.iter()
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.map(|&&s| (true, s)),
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)
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} else if let Some(feature) = feature.strip_prefix('-') {
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// FIXME: Why do we not remove implied features on "-" here?
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// We do the equivalent above in `target_features_cfg`.
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// See <https://github.com/rust-lang/rust/issues/134792>.
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all_rust_features.push((false, feature));
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} else if !feature.is_empty() {
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if diagnostics {
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let feature_state = known_features.iter().find(|&&(v, _, _)| v == feature);
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match feature_state {
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None => {
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let rust_feature =
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known_features.iter().find_map(|&(rust_feature, _, _)| {
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let gcc_features = to_gcc_features(sess, rust_feature);
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if gcc_features.contains(&feature)
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&& !gcc_features.contains(&rust_feature)
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{
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Some(rust_feature)
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} else {
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None
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}
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});
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let unknown_feature = if let Some(rust_feature) = rust_feature {
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UnknownCTargetFeature {
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feature,
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rust_feature: PossibleFeature::Some { rust_feature },
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}
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} else {
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UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
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};
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sess.dcx().emit_warn(unknown_feature);
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}
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Some((_, stability, _)) => {
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if let Err(reason) =
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stability.toggle_allowed(&sess.target, enable_disable == '+')
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sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature });
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}
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}
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}
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// Remove features that are meant for rustc, not LLVM.
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all_rust_features.retain(|(_, feature)| {
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// Retain if it is not a rustc feature
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!RUSTC_SPECIFIC_FEATURES.contains(feature)
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});
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// Check feature validity.
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if diagnostics {
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for &(enable, feature) in &all_rust_features {
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let feature_state = known_features.iter().find(|&&(v, _, _)| v == feature);
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match feature_state {
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None => {
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let rust_feature = known_features.iter().find_map(|&(rust_feature, _, _)| {
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let gcc_features = to_gcc_features(sess, rust_feature);
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if gcc_features.contains(&feature) && !gcc_features.contains(&rust_feature)
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{
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sess.dcx().emit_warn(ForbiddenCTargetFeature { feature, reason });
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} else if stability.requires_nightly().is_some() {
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// An unstable feature. Warn about using it. (It makes little sense
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// to hard-error here since we just warn about fully unknown
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// features above).
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sess.dcx().emit_warn(UnstableCTargetFeature { feature });
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Some(rust_feature)
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} else {
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None
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}
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});
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let unknown_feature = if let Some(rust_feature) = rust_feature {
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UnknownCTargetFeature {
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feature,
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rust_feature: PossibleFeature::Some { rust_feature },
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}
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} else {
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UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
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};
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sess.dcx().emit_warn(unknown_feature);
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}
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Some((_, stability, _)) => {
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if let Err(reason) = stability.toggle_allowed() {
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sess.dcx().emit_warn(ForbiddenCTargetFeature {
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feature,
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enabled: if enable { "enabled" } else { "disabled" },
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reason,
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});
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} else if stability.requires_nightly().is_some() {
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// An unstable feature. Warn about using it. (It makes little sense
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// to hard-error here since we just warn about fully unknown
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// features above).
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sess.dcx().emit_warn(UnstableCTargetFeature { feature });
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}
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}
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// FIXME(nagisa): figure out how to not allocate a full hashset here.
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featsmap.insert(feature, enable_disable == '+');
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}
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// ... otherwise though we run through `to_gcc_features` when
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// Ensure that the features we enable/disable are compatible with the ABI.
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if enable {
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if abi_disable_set.contains(feature) {
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sess.dcx().emit_warn(ForbiddenCTargetFeature {
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feature,
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enabled: "enabled",
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reason: "this feature is incompatible with the target ABI",
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});
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}
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} else {
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if abi_enable_set.contains(feature) {
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sess.dcx().emit_warn(ForbiddenCTargetFeature {
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feature,
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enabled: "disabled",
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reason: "this feature is required by the target ABI",
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});
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}
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}
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// FIXME(nagisa): figure out how to not allocate a full hashset here.
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featsmap.insert(feature, enable);
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}
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}
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// To be sure the ABI-relevant features are all in the right state, we explicitly
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// (un)set them here. This means if the target spec sets those features wrong,
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// we will silently correct them rather than silently producing wrong code.
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// (The target sanity check tries to catch this, but we can't know which features are
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// enabled in GCC by default so we can't be fully sure about that check.)
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for feature in abi_enable {
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all_rust_features.push((true, feature));
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}
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for feature in abi_disable {
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all_rust_features.push((false, feature));
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}
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// Translate this into GCC features.
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let feats = all_rust_features
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.iter()
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.filter_map(|&(enable, feature)| {
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let enable_disable = if enable { '+' } else { '-' };
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// We run through `to_gcc_features` when
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// passing requests down to GCC. This means that all in-language
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// features also work on the command line instead of having two
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// different names when the GCC name and the Rust name differ.
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@ -146,26 +194,12 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
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features
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}
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/// Returns a feature name for the given `+feature` or `-feature` string.
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///
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/// Only allows features that are backend specific (i.e. not [`RUSTC_SPECIFIC_FEATURES`].)
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fn backend_feature_name(s: &str) -> Option<&str> {
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// features must start with a `+` or `-`.
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let feature = s.strip_prefix(&['+', '-'][..]).unwrap_or_else(|| {
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bug!("target feature `{}` must begin with a `+` or `-`", s);
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});
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// Rustc-specific feature requests like `+crt-static` or `-crt-static`
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// are not passed down to GCC.
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if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
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return None;
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}
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Some(feature)
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}
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// To find a list of GCC's names, check https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
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pub fn to_gcc_features<'a>(sess: &Session, s: &'a str) -> SmallVec<[&'a str; 2]> {
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let arch = if sess.target.arch == "x86_64" { "x86" } else { &*sess.target.arch };
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match (arch, s) {
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// FIXME: seems like x87 does not exist?
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("x86", "x87") => smallvec![],
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("x86", "sse4.2") => smallvec!["sse4.2", "crc32"],
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("x86", "pclmulqdq") => smallvec!["pclmul"],
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("x86", "rdrand") => smallvec!["rdrnd"],
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