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diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
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+use crate::dep_graph::{DepNode, WorkProduct, WorkProductId};
+use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt};
+use rustc_attr::InlineAttr;
+use rustc_data_structures::base_n;
+use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
+use rustc_hir::ItemId;
+use rustc_index::vec::Idx;
+use rustc_query_system::ich::StableHashingContext;
+use rustc_session::config::OptLevel;
+use rustc_span::source_map::Span;
+use rustc_span::symbol::Symbol;
+use std::fmt;
+use std::hash::Hash;
+
+/// Describes how a monomorphization will be instantiated in object files.
+#[derive(PartialEq)]
+pub enum InstantiationMode {
+ /// There will be exactly one instance of the given MonoItem. It will have
+ /// external linkage so that it can be linked to from other codegen units.
+ GloballyShared {
+ /// In some compilation scenarios we may decide to take functions that
+ /// are typically `LocalCopy` and instead move them to `GloballyShared`
+ /// to avoid codegenning them a bunch of times. In this situation,
+ /// however, our local copy may conflict with other crates also
+ /// inlining the same function.
+ ///
+ /// This flag indicates that this situation is occurring, and informs
+ /// symbol name calculation that some extra mangling is needed to
+ /// avoid conflicts. Note that this may eventually go away entirely if
+ /// ThinLTO enables us to *always* have a globally shared instance of a
+ /// function within one crate's compilation.
+ may_conflict: bool,
+ },
+
+ /// Each codegen unit containing a reference to the given MonoItem will
+ /// have its own private copy of the function (with internal linkage).
+ LocalCopy,
+}
+
+#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash, HashStable)]
+pub enum MonoItem<'tcx> {
+ Fn(Instance<'tcx>),
+ Static(DefId),
+ GlobalAsm(ItemId),
+}
+
+impl<'tcx> MonoItem<'tcx> {
+ /// Returns `true` if the mono item is user-defined (i.e. not compiler-generated, like shims).
+ pub fn is_user_defined(&self) -> bool {
+ match *self {
+ MonoItem::Fn(instance) => matches!(instance.def, InstanceDef::Item(..)),
+ MonoItem::Static(..) | MonoItem::GlobalAsm(..) => true,
+ }
+ }
+
+ pub fn size_estimate(&self, tcx: TyCtxt<'tcx>) -> usize {
+ match *self {
+ MonoItem::Fn(instance) => {
+ // Estimate the size of a function based on how many statements
+ // it contains.
+ tcx.instance_def_size_estimate(instance.def)
+ }
+ // Conservatively estimate the size of a static declaration
+ // or assembly to be 1.
+ MonoItem::Static(_) | MonoItem::GlobalAsm(_) => 1,
+ }
+ }
+
+ pub fn is_generic_fn(&self) -> bool {
+ match *self {
+ MonoItem::Fn(ref instance) => instance.substs.non_erasable_generics().next().is_some(),
+ MonoItem::Static(..) | MonoItem::GlobalAsm(..) => false,
+ }
+ }
+
+ pub fn symbol_name(&self, tcx: TyCtxt<'tcx>) -> SymbolName<'tcx> {
+ match *self {
+ MonoItem::Fn(instance) => tcx.symbol_name(instance),
+ MonoItem::Static(def_id) => tcx.symbol_name(Instance::mono(tcx, def_id)),
+ MonoItem::GlobalAsm(item_id) => {
+ SymbolName::new(tcx, &format!("global_asm_{:?}", item_id.def_id))
+ }
+ }
+ }
+
+ pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx>) -> InstantiationMode {
+ let generate_cgu_internal_copies = tcx
+ .sess
+ .opts
+ .unstable_opts
+ .inline_in_all_cgus
+ .unwrap_or_else(|| tcx.sess.opts.optimize != OptLevel::No)
+ && !tcx.sess.link_dead_code();
+
+ match *self {
+ MonoItem::Fn(ref instance) => {
+ let entry_def_id = tcx.entry_fn(()).map(|(id, _)| id);
+ // If this function isn't inlined or otherwise has an extern
+ // indicator, then we'll be creating a globally shared version.
+ if tcx.codegen_fn_attrs(instance.def_id()).contains_extern_indicator()
+ || !instance.def.generates_cgu_internal_copy(tcx)
+ || Some(instance.def_id()) == entry_def_id
+ {
+ return InstantiationMode::GloballyShared { may_conflict: false };
+ }
+
+ // At this point we don't have explicit linkage and we're an
+ // inlined function. If we're inlining into all CGUs then we'll
+ // be creating a local copy per CGU.
+ if generate_cgu_internal_copies {
+ return InstantiationMode::LocalCopy;
+ }
+
+ // Finally, if this is `#[inline(always)]` we're sure to respect
+ // that with an inline copy per CGU, but otherwise we'll be
+ // creating one copy of this `#[inline]` function which may
+ // conflict with upstream crates as it could be an exported
+ // symbol.
+ match tcx.codegen_fn_attrs(instance.def_id()).inline {
+ InlineAttr::Always => InstantiationMode::LocalCopy,
+ _ => InstantiationMode::GloballyShared { may_conflict: true },
+ }
+ }
+ MonoItem::Static(..) | MonoItem::GlobalAsm(..) => {
+ InstantiationMode::GloballyShared { may_conflict: false }
+ }
+ }
+ }
+
+ pub fn explicit_linkage(&self, tcx: TyCtxt<'tcx>) -> Option<Linkage> {
+ let def_id = match *self {
+ MonoItem::Fn(ref instance) => instance.def_id(),
+ MonoItem::Static(def_id) => def_id,
+ MonoItem::GlobalAsm(..) => return None,
+ };
+
+ let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
+ codegen_fn_attrs.linkage
+ }
+
+ /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
+ /// predicates.
+ ///
+ /// In order to codegen an item, all of its predicates must hold, because
+ /// otherwise the item does not make sense. Type-checking ensures that
+ /// the predicates of every item that is *used by* a valid item *do*
+ /// hold, so we can rely on that.
+ ///
+ /// However, we codegen collector roots (reachable items) and functions
+ /// in vtables when they are seen, even if they are not used, and so they
+ /// might not be instantiable. For example, a programmer can define this
+ /// public function:
+ ///
+ /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
+ /// <&mut () as Clone>::clone(&s);
+ /// }
+ ///
+ /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
+ /// does not exist. Luckily for us, that function can't ever be used,
+ /// because that would require for `&'a mut (): Clone` to hold, so we
+ /// can just not emit any code, or even a linker reference for it.
+ ///
+ /// Similarly, if a vtable method has such a signature, and therefore can't
+ /// be used, we can just not emit it and have a placeholder (a null pointer,
+ /// which will never be accessed) in its place.
+ pub fn is_instantiable(&self, tcx: TyCtxt<'tcx>) -> bool {
+ debug!("is_instantiable({:?})", self);
+ let (def_id, substs) = match *self {
+ MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
+ MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
+ // global asm never has predicates
+ MonoItem::GlobalAsm(..) => return true,
+ };
+
+ !tcx.subst_and_check_impossible_predicates((def_id, &substs))
+ }
+
+ pub fn local_span(&self, tcx: TyCtxt<'tcx>) -> Option<Span> {
+ match *self {
+ MonoItem::Fn(Instance { def, .. }) => def.def_id().as_local(),
+ MonoItem::Static(def_id) => def_id.as_local(),
+ MonoItem::GlobalAsm(item_id) => Some(item_id.def_id),
+ }
+ .map(|def_id| tcx.def_span(def_id))
+ }
+
+ // Only used by rustc_codegen_cranelift
+ pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx>) -> DepNode {
+ crate::dep_graph::make_compile_mono_item(tcx, self)
+ }
+
+ /// Returns the item's `CrateNum`
+ pub fn krate(&self) -> CrateNum {
+ match self {
+ MonoItem::Fn(ref instance) => instance.def_id().krate,
+ MonoItem::Static(def_id) => def_id.krate,
+ MonoItem::GlobalAsm(..) => LOCAL_CRATE,
+ }
+ }
+}
+
+impl<'tcx> fmt::Display for MonoItem<'tcx> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match *self {
+ MonoItem::Fn(instance) => write!(f, "fn {}", instance),
+ MonoItem::Static(def_id) => {
+ write!(f, "static {}", Instance::new(def_id, InternalSubsts::empty()))
+ }
+ MonoItem::GlobalAsm(..) => write!(f, "global_asm"),
+ }
+ }
+}
+
+#[derive(Debug)]
+pub struct CodegenUnit<'tcx> {
+ /// A name for this CGU. Incremental compilation requires that
+ /// name be unique amongst **all** crates. Therefore, it should
+ /// contain something unique to this crate (e.g., a module path)
+ /// as well as the crate name and disambiguator.
+ name: Symbol,
+ items: FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>,
+ size_estimate: Option<usize>,
+ primary: bool,
+ /// True if this is CGU is used to hold code coverage information for dead code,
+ /// false otherwise.
+ is_code_coverage_dead_code_cgu: bool,
+}
+
+/// Specifies the linkage type for a `MonoItem`.
+///
+/// See <https://llvm.org/docs/LangRef.html#linkage-types> for more details about these variants.
+#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)]
+pub enum Linkage {
+ External,
+ AvailableExternally,
+ LinkOnceAny,
+ LinkOnceODR,
+ WeakAny,
+ WeakODR,
+ Appending,
+ Internal,
+ Private,
+ ExternalWeak,
+ Common,
+}
+
+#[derive(Copy, Clone, PartialEq, Debug, HashStable)]
+pub enum Visibility {
+ Default,
+ Hidden,
+ Protected,
+}
+
+impl<'tcx> CodegenUnit<'tcx> {
+ #[inline]
+ pub fn new(name: Symbol) -> CodegenUnit<'tcx> {
+ CodegenUnit {
+ name,
+ items: Default::default(),
+ size_estimate: None,
+ primary: false,
+ is_code_coverage_dead_code_cgu: false,
+ }
+ }
+
+ pub fn name(&self) -> Symbol {
+ self.name
+ }
+
+ pub fn set_name(&mut self, name: Symbol) {
+ self.name = name;
+ }
+
+ pub fn is_primary(&self) -> bool {
+ self.primary
+ }
+
+ pub fn make_primary(&mut self) {
+ self.primary = true;
+ }
+
+ pub fn items(&self) -> &FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> {
+ &self.items
+ }
+
+ pub fn items_mut(&mut self) -> &mut FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> {
+ &mut self.items
+ }
+
+ pub fn is_code_coverage_dead_code_cgu(&self) -> bool {
+ self.is_code_coverage_dead_code_cgu
+ }
+
+ /// Marks this CGU as the one used to contain code coverage information for dead code.
+ pub fn make_code_coverage_dead_code_cgu(&mut self) {
+ self.is_code_coverage_dead_code_cgu = true;
+ }
+
+ pub fn mangle_name(human_readable_name: &str) -> String {
+ // We generate a 80 bit hash from the name. This should be enough to
+ // avoid collisions and is still reasonably short for filenames.
+ let mut hasher = StableHasher::new();
+ human_readable_name.hash(&mut hasher);
+ let hash: u128 = hasher.finish();
+ let hash = hash & ((1u128 << 80) - 1);
+ base_n::encode(hash, base_n::CASE_INSENSITIVE)
+ }
+
+ pub fn estimate_size(&mut self, tcx: TyCtxt<'tcx>) {
+ // Estimate the size of a codegen unit as (approximately) the number of MIR
+ // statements it corresponds to.
+ self.size_estimate = Some(self.items.keys().map(|mi| mi.size_estimate(tcx)).sum());
+ }
+
+ #[inline]
+ pub fn size_estimate(&self) -> usize {
+ // Should only be called if `estimate_size` has previously been called.
+ self.size_estimate.expect("estimate_size must be called before getting a size_estimate")
+ }
+
+ pub fn modify_size_estimate(&mut self, delta: usize) {
+ assert!(self.size_estimate.is_some());
+ if let Some(size_estimate) = self.size_estimate {
+ self.size_estimate = Some(size_estimate + delta);
+ }
+ }
+
+ pub fn contains_item(&self, item: &MonoItem<'tcx>) -> bool {
+ self.items().contains_key(item)
+ }
+
+ pub fn work_product_id(&self) -> WorkProductId {
+ WorkProductId::from_cgu_name(self.name().as_str())
+ }
+
+ pub fn previous_work_product(&self, tcx: TyCtxt<'_>) -> WorkProduct {
+ let work_product_id = self.work_product_id();
+ tcx.dep_graph
+ .previous_work_product(&work_product_id)
+ .unwrap_or_else(|| panic!("Could not find work-product for CGU `{}`", self.name()))
+ }
+
+ pub fn items_in_deterministic_order(
+ &self,
+ tcx: TyCtxt<'tcx>,
+ ) -> Vec<(MonoItem<'tcx>, (Linkage, Visibility))> {
+ // The codegen tests rely on items being process in the same order as
+ // they appear in the file, so for local items, we sort by node_id first
+ #[derive(PartialEq, Eq, PartialOrd, Ord)]
+ pub struct ItemSortKey<'tcx>(Option<usize>, SymbolName<'tcx>);
+
+ fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx>, item: MonoItem<'tcx>) -> ItemSortKey<'tcx> {
+ ItemSortKey(
+ match item {
+ MonoItem::Fn(ref instance) => {
+ match instance.def {
+ // We only want to take HirIds of user-defined
+ // instances into account. The others don't matter for
+ // the codegen tests and can even make item order
+ // unstable.
+ InstanceDef::Item(def) => def.did.as_local().map(Idx::index),
+ InstanceDef::VTableShim(..)
+ | InstanceDef::ReifyShim(..)
+ | InstanceDef::Intrinsic(..)
+ | InstanceDef::FnPtrShim(..)
+ | InstanceDef::Virtual(..)
+ | InstanceDef::ClosureOnceShim { .. }
+ | InstanceDef::DropGlue(..)
+ | InstanceDef::CloneShim(..) => None,
+ }
+ }
+ MonoItem::Static(def_id) => def_id.as_local().map(Idx::index),
+ MonoItem::GlobalAsm(item_id) => Some(item_id.def_id.index()),
+ },
+ item.symbol_name(tcx),
+ )
+ }
+
+ let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect();
+ items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
+ items
+ }
+
+ pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx>) -> DepNode {
+ crate::dep_graph::make_compile_codegen_unit(tcx, self.name())
+ }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
+ fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
+ let CodegenUnit {
+ ref items,
+ name,
+ // The size estimate is not relevant to the hash
+ size_estimate: _,
+ primary: _,
+ is_code_coverage_dead_code_cgu,
+ } = *self;
+
+ name.hash_stable(hcx, hasher);
+ is_code_coverage_dead_code_cgu.hash_stable(hcx, hasher);
+
+ let mut items: Vec<(Fingerprint, _)> = items
+ .iter()
+ .map(|(mono_item, &attrs)| {
+ let mut hasher = StableHasher::new();
+ mono_item.hash_stable(hcx, &mut hasher);
+ let mono_item_fingerprint = hasher.finish();
+ (mono_item_fingerprint, attrs)
+ })
+ .collect();
+
+ items.sort_unstable_by_key(|i| i.0);
+ items.hash_stable(hcx, hasher);
+ }
+}
+
+pub struct CodegenUnitNameBuilder<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ cache: FxHashMap<CrateNum, String>,
+}
+
+impl<'tcx> CodegenUnitNameBuilder<'tcx> {
+ pub fn new(tcx: TyCtxt<'tcx>) -> Self {
+ CodegenUnitNameBuilder { tcx, cache: Default::default() }
+ }
+
+ /// CGU names should fulfill the following requirements:
+ /// - They should be able to act as a file name on any kind of file system
+ /// - They should not collide with other CGU names, even for different versions
+ /// of the same crate.
+ ///
+ /// Consequently, we don't use special characters except for '.' and '-' and we
+ /// prefix each name with the crate-name and crate-disambiguator.
+ ///
+ /// This function will build CGU names of the form:
+ ///
+ /// ```text
+ /// <crate-name>.<crate-disambiguator>[-in-<local-crate-id>](-<component>)*[.<special-suffix>]
+ /// <local-crate-id> = <local-crate-name>.<local-crate-disambiguator>
+ /// ```
+ ///
+ /// The '.' before `<special-suffix>` makes sure that names with a special
+ /// suffix can never collide with a name built out of regular Rust
+ /// identifiers (e.g., module paths).
+ pub fn build_cgu_name<I, C, S>(
+ &mut self,
+ cnum: CrateNum,
+ components: I,
+ special_suffix: Option<S>,
+ ) -> Symbol
+ where
+ I: IntoIterator<Item = C>,
+ C: fmt::Display,
+ S: fmt::Display,
+ {
+ let cgu_name = self.build_cgu_name_no_mangle(cnum, components, special_suffix);
+
+ if self.tcx.sess.opts.unstable_opts.human_readable_cgu_names {
+ cgu_name
+ } else {
+ Symbol::intern(&CodegenUnit::mangle_name(cgu_name.as_str()))
+ }
+ }
+
+ /// Same as `CodegenUnit::build_cgu_name()` but will never mangle the
+ /// resulting name.
+ pub fn build_cgu_name_no_mangle<I, C, S>(
+ &mut self,
+ cnum: CrateNum,
+ components: I,
+ special_suffix: Option<S>,
+ ) -> Symbol
+ where
+ I: IntoIterator<Item = C>,
+ C: fmt::Display,
+ S: fmt::Display,
+ {
+ use std::fmt::Write;
+
+ let mut cgu_name = String::with_capacity(64);
+
+ // Start out with the crate name and disambiguator
+ let tcx = self.tcx;
+ let crate_prefix = self.cache.entry(cnum).or_insert_with(|| {
+ // Whenever the cnum is not LOCAL_CRATE we also mix in the
+ // local crate's ID. Otherwise there can be collisions between CGUs
+ // instantiating stuff for upstream crates.
+ let local_crate_id = if cnum != LOCAL_CRATE {
+ let local_stable_crate_id = tcx.sess.local_stable_crate_id();
+ format!(
+ "-in-{}.{:08x}",
+ tcx.crate_name(LOCAL_CRATE),
+ local_stable_crate_id.to_u64() as u32,
+ )
+ } else {
+ String::new()
+ };
+
+ let stable_crate_id = tcx.sess.local_stable_crate_id();
+ format!(
+ "{}.{:08x}{}",
+ tcx.crate_name(cnum),
+ stable_crate_id.to_u64() as u32,
+ local_crate_id,
+ )
+ });
+
+ write!(cgu_name, "{}", crate_prefix).unwrap();
+
+ // Add the components
+ for component in components {
+ write!(cgu_name, "-{}", component).unwrap();
+ }
+
+ if let Some(special_suffix) = special_suffix {
+ // We add a dot in here so it cannot clash with anything in a regular
+ // Rust identifier
+ write!(cgu_name, ".{}", special_suffix).unwrap();
+ }
+
+ Symbol::intern(&cgu_name)
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-12 13:06:12 +0000