diff --git a/src/librustc/mir/mono.rs b/src/librustc/mir/mono.rs index ca79bc15358..9ba0bb3eb2d 100644 --- a/src/librustc/mir/mono.rs +++ b/src/librustc/mir/mono.rs @@ -1,15 +1,44 @@ 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, TyCtxt, SymbolName, subst::InternalSubsts}; use crate::util::nodemap::FxHashMap; +use crate::ty::print::obsolete::DefPathBasedNames; 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>), @@ -31,6 +60,166 @@ impl<'tcx> MonoItem<'tcx> { 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<'a, '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<'a, '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<'a, '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<'a, '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<'a, '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<'a, 'tcx>(tcx: TyCtxt<'a, '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<'a, '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> { diff --git a/src/librustc_codegen_ssa/base.rs b/src/librustc_codegen_ssa/base.rs index fc3d0712fca..34e5b0681de 100644 --- a/src/librustc_codegen_ssa/base.rs +++ b/src/librustc_codegen_ssa/base.rs @@ -20,11 +20,10 @@ use rustc::hir::def_id::{DefId, LOCAL_CRATE}; use rustc::middle::cstore::EncodedMetadata; use rustc::middle::lang_items::StartFnLangItem; use rustc::middle::weak_lang_items; -use rustc::mir::mono::{CodegenUnitNameBuilder, CodegenUnit}; +use rustc::mir::mono::{CodegenUnitNameBuilder, CodegenUnit, MonoItem}; use rustc::ty::{self, Ty, TyCtxt, Instance}; use rustc::ty::layout::{self, Align, TyLayout, LayoutOf, VariantIdx, HasTyCtxt}; use rustc::ty::query::Providers; -use rustc::ty::print::obsolete::DefPathBasedNames; use rustc::middle::cstore::{self, LinkagePreference}; use rustc::util::common::{time, print_time_passes_entry}; use rustc::session::config::{self, EntryFnType, Lto}; @@ -42,7 +41,6 @@ use crate::callee; use crate::common::{RealPredicate, TypeKind, IntPredicate}; use crate::meth; use crate::mir; -use crate::mono_item::MonoItem; use crate::traits::*; diff --git a/src/librustc_codegen_ssa/mono_item.rs b/src/librustc_codegen_ssa/mono_item.rs index 60d75480e61..1c9c86a5f5d 100644 --- a/src/librustc_codegen_ssa/mono_item.rs +++ b/src/librustc_codegen_ssa/mono_item.rs @@ -1,19 +1,18 @@ use rustc::hir; use rustc::mir::mono::{Linkage, Visibility}; use rustc::ty::layout::HasTyCtxt; -use std::fmt; use crate::base; use crate::traits::*; -pub use rustc::mir::mono::MonoItem; +use rustc::mir::mono::MonoItem; -pub use rustc_mir::monomorphize::item::MonoItemExt as BaseMonoItemExt; +pub trait MonoItemExt<'a, 'tcx: 'a> { + fn as_mono_item(&self) -> &MonoItem<'tcx>; -pub trait MonoItemExt<'a, 'tcx: 'a>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> { fn define>(&self, cx: &'a Bx::CodegenCx) { debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}", - self.to_string(cx.tcx(), true), - self.to_raw_string(), + self.as_mono_item().to_string(cx.tcx(), true), + self.as_mono_item().to_raw_string(), cx.codegen_unit().name()); match *self.as_mono_item() { @@ -34,8 +33,8 @@ pub trait MonoItemExt<'a, 'tcx: 'a>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> { } debug!("END IMPLEMENTING '{} ({})' in cgu {}", - self.to_string(cx.tcx(), true), - self.to_raw_string(), + self.as_mono_item().to_string(cx.tcx(), true), + self.as_mono_item().to_raw_string(), cx.codegen_unit().name()); } @@ -46,11 +45,11 @@ pub trait MonoItemExt<'a, 'tcx: 'a>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> { visibility: Visibility ) { debug!("BEGIN PREDEFINING '{} ({})' in cgu {}", - self.to_string(cx.tcx(), true), - self.to_raw_string(), + self.as_mono_item().to_string(cx.tcx(), true), + self.as_mono_item().to_raw_string(), cx.codegen_unit().name()); - let symbol_name = self.symbol_name(cx.tcx()).as_str(); + let symbol_name = self.as_mono_item().symbol_name(cx.tcx()).as_str(); debug!("symbol {}", &symbol_name); @@ -65,8 +64,8 @@ pub trait MonoItemExt<'a, 'tcx: 'a>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> { } debug!("END PREDEFINING '{} ({})' in cgu {}", - self.to_string(cx.tcx(), true), - self.to_raw_string(), + self.as_mono_item().to_string(cx.tcx(), true), + self.as_mono_item().to_raw_string(), cx.codegen_unit().name()); } @@ -87,4 +86,8 @@ pub trait MonoItemExt<'a, 'tcx: 'a>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> { } } -impl<'a, 'tcx: 'a> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {} +impl<'a, 'tcx: 'a> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> { + fn as_mono_item(&self) -> &MonoItem<'tcx> { + self + } +} diff --git a/src/librustc_codegen_utils/symbol_names.rs b/src/librustc_codegen_utils/symbol_names.rs index 9f710d7932d..47dc4e5b2ca 100644 --- a/src/librustc_codegen_utils/symbol_names.rs +++ b/src/librustc_codegen_utils/symbol_names.rs @@ -93,8 +93,7 @@ use rustc::hir::CodegenFnAttrFlags; use rustc::session::config::SymbolManglingVersion; use rustc::ty::query::Providers; use rustc::ty::{self, TyCtxt, Instance}; -use rustc::mir::mono::MonoItem; -use rustc_mir::monomorphize::item::{InstantiationMode, MonoItemExt}; +use rustc::mir::mono::{MonoItem, InstantiationMode}; use syntax_pos::symbol::InternedString; diff --git a/src/librustc_mir/monomorphize/collector.rs b/src/librustc_mir/monomorphize/collector.rs index 2fc42098669..eed051449e1 100644 --- a/src/librustc_mir/monomorphize/collector.rs +++ b/src/librustc_mir/monomorphize/collector.rs @@ -187,15 +187,13 @@ use rustc::ty::adjustment::{CustomCoerceUnsized, PointerCast}; use rustc::session::config::EntryFnType; use rustc::mir::{self, Location, Place, PlaceBase, Promoted, Static, StaticKind}; use rustc::mir::visit::Visitor as MirVisitor; -use rustc::mir::mono::MonoItem; +use rustc::mir::mono::{MonoItem, InstantiationMode}; use rustc::mir::interpret::{Scalar, GlobalId, GlobalAlloc, ErrorHandled}; use crate::monomorphize; use rustc::util::nodemap::{FxHashSet, FxHashMap, DefIdMap}; use rustc::util::common::time; -use crate::monomorphize::item::{MonoItemExt, InstantiationMode}; - use rustc_data_structures::bit_set::GrowableBitSet; use rustc_data_structures::sync::{MTRef, MTLock, ParallelIterator, par_iter}; diff --git a/src/librustc_mir/monomorphize/mod.rs b/src/librustc_mir/monomorphize/mod.rs index f7b32dc84bd..51bcbff7f32 100644 --- a/src/librustc_mir/monomorphize/mod.rs +++ b/src/librustc_mir/monomorphize/mod.rs @@ -2,10 +2,7 @@ use rustc::traits; use rustc::ty::adjustment::CustomCoerceUnsized; use rustc::ty::{self, Ty, TyCtxt}; -pub use self::item::MonoItemExt; - pub mod collector; -pub mod item; pub mod partitioning; pub fn custom_coerce_unsize_info<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, diff --git a/src/librustc_mir/monomorphize/partitioning.rs b/src/librustc_mir/monomorphize/partitioning.rs index cc90d6c95c9..6a7f67da1bf 100644 --- a/src/librustc_mir/monomorphize/partitioning.rs +++ b/src/librustc_mir/monomorphize/partitioning.rs @@ -108,11 +108,10 @@ use rustc::ty::print::characteristic_def_id_of_type; use rustc::ty::query::Providers; use rustc::util::common::time; use rustc::util::nodemap::{DefIdSet, FxHashMap, FxHashSet}; -use rustc::mir::mono::MonoItem; +use rustc::mir::mono::{MonoItem, InstantiationMode}; use crate::monomorphize::collector::InliningMap; use crate::monomorphize::collector::{self, MonoItemCollectionMode}; -use crate::monomorphize::item::{MonoItemExt, InstantiationMode}; pub enum PartitioningStrategy { /// Generates one codegen unit per source-level module.