diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/llvm_util.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm_util.rs | 279 |
1 files changed, 63 insertions, 216 deletions
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs index 0e77bc43df8..6fd07d562af 100644 --- a/compiler/rustc_codegen_llvm/src/llvm_util.rs +++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs @@ -6,27 +6,20 @@ use std::sync::Once; use std::{ptr, slice, str}; use libc::c_int; -use rustc_codegen_ssa::TargetConfig; use rustc_codegen_ssa::base::wants_wasm_eh; -use rustc_codegen_ssa::codegen_attrs::check_tied_features; -use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_codegen_ssa::target_features::cfg_target_feature; +use rustc_codegen_ssa::{TargetConfig, target_features}; +use rustc_data_structures::fx::FxHashSet; use rustc_data_structures::small_c_str::SmallCStr; -use rustc_data_structures::unord::UnordSet; use rustc_fs_util::path_to_c_string; use rustc_middle::bug; use rustc_session::Session; use rustc_session::config::{PrintKind, PrintRequest}; -use rustc_session::features::{StabilityExt, retpoline_features_by_flags}; -use rustc_span::Symbol; use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport}; -use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES}; use smallvec::{SmallVec, smallvec}; use crate::back::write::create_informational_target_machine; -use crate::errors::{ - FixedX18InvalidArch, PossibleFeature, UnknownCTargetFeature, UnknownCTargetFeaturePrefix, -}; -use crate::llvm; +use crate::{errors, llvm}; static INIT: Once = Once::new(); @@ -195,15 +188,6 @@ impl<'a> LLVMFeature<'a> { ) -> Self { Self { llvm_feature_name, dependencies } } - - fn contains(&'a self, feat: &str) -> bool { - self.iter().any(|dep| dep == feat) - } - - fn iter(&'a self) -> impl Iterator<Item = &'a str> { - let dependencies = self.dependencies.iter().map(|feat| feat.as_str()); - std::iter::once(self.llvm_feature_name).chain(dependencies) - } } impl<'a> IntoIterator for LLVMFeature<'a> { @@ -216,18 +200,22 @@ impl<'a> IntoIterator for LLVMFeature<'a> { } } -// WARNING: the features after applying `to_llvm_features` must be known -// to LLVM or the feature detection code will walk past the end of the feature -// array, leading to crashes. -// -// To find a list of LLVM's names, see llvm-project/llvm/lib/Target/{ARCH}/*.td -// where `{ARCH}` is the architecture name. Look for instances of `SubtargetFeature`. -// -// Check the current rustc fork of LLVM in the repo at https://github.com/rust-lang/llvm-project/. -// The commit in use can be found via the `llvm-project` submodule in -// https://github.com/rust-lang/rust/tree/master/src Though note that Rust can also be build with -// an external precompiled version of LLVM which might lead to failures if the oldest tested / -// supported LLVM version doesn't yet support the relevant intrinsics. +/// Convert a Rust feature name to an LLVM feature name. Returning `None` means the +/// feature should be skipped, usually because it is not supported by the current +/// LLVM version. +/// +/// WARNING: the features after applying `to_llvm_features` must be known +/// to LLVM or the feature detection code will walk past the end of the feature +/// array, leading to crashes. +/// +/// To find a list of LLVM's names, see llvm-project/llvm/lib/Target/{ARCH}/*.td +/// where `{ARCH}` is the architecture name. Look for instances of `SubtargetFeature`. +/// +/// Check the current rustc fork of LLVM in the repo at +/// <https://github.com/rust-lang/llvm-project/>. The commit in use can be found via the +/// `llvm-project` submodule in <https://github.com/rust-lang/rust/tree/master/src> Though note that +/// Rust can also be build with an external precompiled version of LLVM which might lead to failures +/// if the oldest tested / supported LLVM version doesn't yet support the relevant intrinsics. pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFeature<'a>> { let arch = if sess.target.arch == "x86_64" { "x86" @@ -343,98 +331,25 @@ pub(crate) fn target_config(sess: &Session) -> TargetConfig { // the target CPU, that is still expanded to target features (with all their implied features) // by LLVM. let target_machine = create_informational_target_machine(sess, true); - // Compute which of the known target features are enabled in the 'base' target machine. We only - // consider "supported" features; "forbidden" features are not reflected in `cfg` as of now. - let mut features: FxHashSet<Symbol> = sess - .target - .rust_target_features() - .iter() - .filter(|(feature, _, _)| { - // skip checking special features, as LLVM may not understand them - if RUSTC_SPECIAL_FEATURES.contains(feature) { - return true; - } - if let Some(feat) = to_llvm_features(sess, feature) { - for llvm_feature in feat { - let cstr = SmallCStr::new(llvm_feature); - // `LLVMRustHasFeature` is moderately expensive. On targets with many - // features (e.g. x86) these calls take a non-trivial fraction of runtime - // when compiling very small programs. - if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } { - return false; - } + + let (unstable_target_features, target_features) = cfg_target_feature(sess, |feature| { + if let Some(feat) = to_llvm_features(sess, feature) { + // All the LLVM features this expands to must be enabled. + for llvm_feature in feat { + let cstr = SmallCStr::new(llvm_feature); + // `LLVMRustHasFeature` is moderately expensive. On targets with many + // features (e.g. x86) these calls take a non-trivial fraction of runtime + // when compiling very small programs. + if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } { + return false; } - true - } else { - false } - }) - .map(|(feature, _, _)| Symbol::intern(feature)) - .collect(); - - // Add enabled and remove disabled features. - 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 { - // Also add all transitively implied features. - - // We don't care about the order in `features` since the only thing we use it for is the - // `features.contains` below. - #[allow(rustc::potential_query_instability)] - features.extend( - sess.target - .implied_target_features(feature.as_str()) - .iter() - .map(|s| Symbol::intern(s)), - ); + true } else { - // Remove transitively reverse-implied features. - - // We don't care about the order in `features` since the only thing we use it for is the - // `features.contains` below. - #[allow(rustc::potential_query_instability)] - features.retain(|f| { - if sess.target.implied_target_features(f.as_str()).contains(&feature.as_str()) { - // If `f` if implies `feature`, then `!feature` implies `!f`, so we have to - // remove `f`. (This is the standard logical contraposition principle.) - false - } else { - // We can keep `f`. - true - } - }); + false } - } - - // Filter enabled features based on feature gates. - let f = |allow_unstable| { - sess.target - .rust_target_features() - .iter() - .filter_map(|(feature, gate, _)| { - // The `allow_unstable` set is used by rustc internally to determined which target - // features are truly available, so we want to return even perma-unstable - // "forbidden" features. - if allow_unstable - || (gate.in_cfg() - && (sess.is_nightly_build() || gate.requires_nightly().is_none())) - { - Some(Symbol::intern(feature)) - } else { - None - } - }) - .filter(|feature| features.contains(&feature)) - .collect() - }; + }); - let target_features = f(false); - let unstable_target_features = f(true); let mut cfg = TargetConfig { target_features, unstable_target_features, @@ -707,10 +622,18 @@ pub(crate) fn target_cpu(sess: &Session) -> &str { handle_native(cpu_name) } -fn llvm_features_by_flags(sess: &Session) -> Vec<&str> { - let mut features: Vec<&str> = Vec::new(); - retpoline_features_by_flags(sess, &mut features); - features +/// The target features for compiler flags other than `-Ctarget-features`. +fn llvm_features_by_flags(sess: &Session, features: &mut Vec<String>) { + target_features::retpoline_features_by_flags(sess, features); + + // -Zfixed-x18 + if sess.opts.unstable_opts.fixed_x18 { + if sess.target.arch != "aarch64" { + sess.dcx().emit_fatal(errors::FixedX18InvalidArch { arch: &sess.target.arch }); + } else { + features.push("+reserve-x18".into()); + } + } } /// The list of LLVM features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`, @@ -777,6 +700,8 @@ pub(crate) fn global_llvm_features( .split(',') .filter(|v| !v.is_empty()) // Drop +v8plus feature introduced in LLVM 20. + // (Hard-coded target features do not go through `to_llvm_feature` since they already + // are LLVM feature names, hence we need a special case here.) .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0)) .map(String::from), ); @@ -787,86 +712,23 @@ pub(crate) fn global_llvm_features( // -Ctarget-features if !only_base_features { - let known_features = sess.target.rust_target_features(); - // Will only be filled when `diagnostics` is set! - let mut featsmap = FxHashMap::default(); - - // Compute implied features - let mut all_rust_features = vec![]; - for feature in sess.opts.cg.target_feature.split(',').chain(llvm_features_by_flags(sess)) { - if let Some(feature) = feature.strip_prefix('+') { - all_rust_features.extend( - UnordSet::from(sess.target.implied_target_features(feature)) - .to_sorted_stable_ord() - .iter() - .map(|&&s| (true, s)), - ) - } else if let Some(feature) = feature.strip_prefix('-') { - // FIXME: Why do we not remove implied features on "-" here? - // We do the equivalent above in `target_config`. - // See <https://github.com/rust-lang/rust/issues/134792>. - all_rust_features.push((false, feature)); - } else if !feature.is_empty() { - if diagnostics { - sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature }); - } - } - } - // Remove features that are meant for rustc, not LLVM. - all_rust_features.retain(|(_, feature)| { - // Retain if it is not a rustc feature - !RUSTC_SPECIFIC_FEATURES.contains(feature) - }); - - // Check feature validity. - if diagnostics { - for &(enable, feature) in &all_rust_features { - 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 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); - } - Some((_, stability, _)) => { - stability.verify_feature_enabled_by_flag(sess, enable, feature); - } - } - - // FIXME(nagisa): figure out how to not allocate a full hashset here. - featsmap.insert(feature, enable); - } - } - - // Translate this into LLVM features. - let feats = all_rust_features - .iter() - .filter_map(|&(enable, feature)| { + target_features::flag_to_backend_features( + sess, + diagnostics, + |feature| { + to_llvm_features(sess, feature) + .map(|f| SmallVec::<[&str; 2]>::from_iter(f.into_iter())) + .unwrap_or_default() + }, + |feature, enable| { let enable_disable = if enable { '+' } else { '-' }; // 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)?; + let Some(llvm_feature) = to_llvm_features(sess, feature) else { return }; - Some( + features.extend( std::iter::once(format!( "{}{}", enable_disable, llvm_feature.llvm_feature_name @@ -881,27 +743,12 @@ pub(crate) fn global_llvm_features( }, )), ) - }) - .flatten(); - features.extend(feats); - - if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) { - sess.dcx().emit_err(rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable { - features: f, - span: None, - missing_features: None, - }); - } + }, + ); } - // -Zfixed-x18 - if sess.opts.unstable_opts.fixed_x18 { - if sess.target.arch != "aarch64" { - sess.dcx().emit_fatal(FixedX18InvalidArch { arch: &sess.target.arch }); - } else { - features.push("+reserve-x18".into()); - } - } + // We add this in the "base target" so that these show up in `sess.unstable_target_features`. + llvm_features_by_flags(sess, &mut features); features } |