X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Flibrustc%2Fmir%2Fmono.rs;h=cf1126efc0f86e5d01caa974c14ed9acdc3e5a00;hb=fff08cb04389497d254fb40948674cbbee402908;hp=ca79bc15358c500fb6f3216af3933ddf43af2e87;hpb=eebe62aaa1e31151269d19ec71248215a40f6417;p=rust.git diff --git a/src/librustc/mir/mono.rs b/src/librustc/mir/mono.rs index ca79bc15358..cf1126efc0f 100644 --- a/src/librustc/mir/mono.rs +++ b/src/librustc/mir/mono.rs @@ -1,15 +1,45 @@ use crate::hir::def_id::{DefId, CrateNum, LOCAL_CRATE}; use crate::hir::HirId; use syntax::symbol::InternedString; -use crate::ty::{Instance, TyCtxt}; +use syntax::attr::InlineAttr; +use syntax::source_map::Span; +use crate::ty::{Instance, InstanceDef, TyCtxt, SymbolName, subst::InternalSubsts}; use crate::util::nodemap::FxHashMap; +use crate::ty::print::obsolete::DefPathBasedNames; +use crate::dep_graph::{WorkProductId, DepNode, WorkProduct, DepConstructor}; use rustc_data_structures::base_n; use rustc_data_structures::stable_hasher::{HashStable, StableHasherResult, StableHasher}; use crate::ich::{Fingerprint, StableHashingContext, NodeIdHashingMode}; +use crate::session::config::OptLevel; use std::fmt; use std::hash::Hash; +/// Describes how a monomorphization will be instantiated in object files. +#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] +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)] pub enum MonoItem<'tcx> { Fn(Instance<'tcx>), @@ -18,7 +48,7 @@ pub enum MonoItem<'tcx> { } impl<'tcx> MonoItem<'tcx> { - pub fn size_estimate<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> usize { + pub fn size_estimate(&self, tcx: TyCtxt<'tcx, 'tcx>) -> usize { match *self { MonoItem::Fn(instance) => { // Estimate the size of a function based on how many statements @@ -31,6 +61,165 @@ pub fn size_estimate<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> usize { 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, 'tcx>) -> SymbolName { + match *self { + MonoItem::Fn(instance) => tcx.symbol_name(instance), + MonoItem::Static(def_id) => { + tcx.symbol_name(Instance::mono(tcx, def_id)) + } + MonoItem::GlobalAsm(hir_id) => { + let def_id = tcx.hir().local_def_id_from_hir_id(hir_id); + SymbolName { + name: InternedString::intern(&format!("global_asm_{:?}", def_id)) + } + } + } + } + + pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx, 'tcx>) -> InstantiationMode { + let inline_in_all_cgus = + tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| { + tcx.sess.opts.optimize != OptLevel::No + }) && !tcx.sess.opts.cg.link_dead_code; + + match *self { + MonoItem::Fn(ref instance) => { + let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id); + // If this function isn't inlined or otherwise has explicit + // linkage, then we'll be creating a globally shared version. + if self.explicit_linkage(tcx).is_some() || + !instance.def.requires_local(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 inline_in_all_cgus { + 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, 'tcx>) -> Option { + 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, '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.substitute_normalize_and_test_predicates((def_id, &substs)) + } + + pub fn to_string(&self, tcx: TyCtxt<'tcx, 'tcx>, debug: bool) -> String { + return match *self { + MonoItem::Fn(instance) => { + to_string_internal(tcx, "fn ", instance, debug) + }, + MonoItem::Static(def_id) => { + let instance = Instance::new(def_id, tcx.intern_substs(&[])); + to_string_internal(tcx, "static ", instance, debug) + }, + MonoItem::GlobalAsm(..) => { + "global_asm".to_string() + } + }; + + fn to_string_internal<'tcx>( + tcx: TyCtxt<'tcx, 'tcx>, + prefix: &str, + instance: Instance<'tcx>, + debug: bool, + ) -> String { + let mut result = String::with_capacity(32); + result.push_str(prefix); + let printer = DefPathBasedNames::new(tcx, false, false); + printer.push_instance_as_string(instance, &mut result, debug); + result + } + } + + pub fn local_span(&self, tcx: TyCtxt<'tcx, 'tcx>) -> Option { + match *self { + MonoItem::Fn(Instance { def, .. }) => { + tcx.hir().as_local_hir_id(def.def_id()) + } + MonoItem::Static(def_id) => { + tcx.hir().as_local_hir_id(def_id) + } + MonoItem::GlobalAsm(hir_id) => { + Some(hir_id) + } + }.map(|hir_id| tcx.hir().span_by_hir_id(hir_id)) + } } impl<'a, 'tcx> HashStable> for MonoItem<'tcx> { @@ -144,7 +333,7 @@ pub fn mangle_name(human_readable_name: &str) -> String { base_n::encode(hash, base_n::CASE_INSENSITIVE) } - pub fn estimate_size<'a>(&mut self, tcx: TyCtxt<'a, 'tcx, 'tcx>) { + pub fn estimate_size(&mut self, tcx: TyCtxt<'tcx, '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()); @@ -161,6 +350,72 @@ pub fn modify_size_estimate(&mut self, delta: usize) { 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 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, '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(Option, SymbolName); + + fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, item: MonoItem<'tcx>) -> ItemSortKey { + 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_id) => { + tcx.hir().as_local_hir_id(def_id) + } + InstanceDef::VtableShim(..) | + InstanceDef::Intrinsic(..) | + InstanceDef::FnPtrShim(..) | + InstanceDef::Virtual(..) | + InstanceDef::ClosureOnceShim { .. } | + InstanceDef::DropGlue(..) | + InstanceDef::CloneShim(..) => { + None + } + } + } + MonoItem::Static(def_id) => { + tcx.hir().as_local_hir_id(def_id) + } + MonoItem::GlobalAsm(hir_id) => { + Some(hir_id) + } + }, 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, 'tcx>) -> DepNode { + DepNode::new(tcx, DepConstructor::CompileCodegenUnit(self.name().clone())) + } } impl<'a, 'tcx> HashStable> for CodegenUnit<'tcx> { @@ -188,14 +443,13 @@ fn hash_stable(&self, } } -pub struct CodegenUnitNameBuilder<'a, 'gcx: 'tcx, 'tcx: 'a> { - tcx: TyCtxt<'a, 'gcx, 'tcx>, +pub struct CodegenUnitNameBuilder<'gcx, 'tcx> { + tcx: TyCtxt<'gcx, 'tcx>, cache: FxHashMap, } -impl<'a, 'gcx: 'tcx, 'tcx: 'a> CodegenUnitNameBuilder<'a, 'gcx, 'tcx> { - - pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Self { +impl CodegenUnitNameBuilder<'gcx, 'tcx> { + pub fn new(tcx: TyCtxt<'gcx, 'tcx>) -> Self { CodegenUnitNameBuilder { tcx, cache: Default::default(),