812 lines
33 KiB
Rust
812 lines
33 KiB
Rust
use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
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use crate::ty::print::{FmtPrinter, Printer};
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use crate::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
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use crate::ty::{EarlyBinder, GenericArgs, GenericArgsRef, TypeVisitableExt};
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use rustc_errors::ErrorGuaranteed;
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use rustc_hir::def::Namespace;
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use rustc_hir::def_id::{CrateNum, DefId};
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use rustc_hir::lang_items::LangItem;
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use rustc_index::bit_set::FiniteBitSet;
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use rustc_macros::HashStable;
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use rustc_middle::ty::normalize_erasing_regions::NormalizationError;
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use rustc_span::Symbol;
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use std::fmt;
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/// A monomorphized `InstanceDef`.
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///
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/// Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type
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/// simply couples a potentially generic `InstanceDef` with some args, and codegen and const eval
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/// will do all required substitution as they run.
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///
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/// Note: the `Lift` impl is currently not used by rustc, but is used by
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/// rustc_codegen_cranelift when the `jit` feature is enabled.
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#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
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#[derive(HashStable, Lift, TypeFoldable, TypeVisitable)]
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pub struct Instance<'tcx> {
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pub def: InstanceDef<'tcx>,
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pub args: GenericArgsRef<'tcx>,
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}
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
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#[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable, Lift)]
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pub enum InstanceDef<'tcx> {
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/// A user-defined callable item.
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///
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/// This includes:
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/// - `fn` items
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/// - closures
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/// - generators
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Item(DefId),
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/// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI).
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///
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/// Alongside `Virtual`, this is the only `InstanceDef` that does not have its own callable MIR.
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/// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the
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/// caller.
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Intrinsic(DefId),
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/// `<T as Trait>::method` where `method` receives unsizeable `self: Self` (part of the
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/// `unsized_locals` feature).
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///
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/// The generated shim will take `Self` via `*mut Self` - conceptually this is `&owned Self` -
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/// and dereference the argument to call the original function.
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VTableShim(DefId),
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/// `fn()` pointer where the function itself cannot be turned into a pointer.
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///
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/// One example is `<dyn Trait as Trait>::fn`, where the shim contains
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/// a virtual call, which codegen supports only via a direct call to the
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/// `<dyn Trait as Trait>::fn` instance (an `InstanceDef::Virtual`).
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///
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/// Another example is functions annotated with `#[track_caller]`, which
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/// must have their implicit caller location argument populated for a call.
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/// Because this is a required part of the function's ABI but can't be tracked
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/// as a property of the function pointer, we use a single "caller location"
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/// (the definition of the function itself).
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ReifyShim(DefId),
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/// `<fn() as FnTrait>::call_*` (generated `FnTrait` implementation for `fn()` pointers).
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///
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/// `DefId` is `FnTrait::call_*`.
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FnPtrShim(DefId, Ty<'tcx>),
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/// Dynamic dispatch to `<dyn Trait as Trait>::fn`.
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///
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/// This `InstanceDef` does not have callable MIR. Calls to `Virtual` instances must be
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/// codegen'd as virtual calls through the vtable.
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///
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/// If this is reified to a `fn` pointer, a `ReifyShim` is used (see `ReifyShim` above for more
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/// details on that).
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Virtual(DefId, usize),
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/// `<[FnMut closure] as FnOnce>::call_once`.
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///
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/// The `DefId` is the ID of the `call_once` method in `FnOnce`.
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ClosureOnceShim { call_once: DefId, track_caller: bool },
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/// Compiler-generated accessor for thread locals which returns a reference to the thread local
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/// the `DefId` defines. This is used to export thread locals from dylibs on platforms lacking
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/// native support.
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ThreadLocalShim(DefId),
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/// `core::ptr::drop_in_place::<T>`.
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///
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/// The `DefId` is for `core::ptr::drop_in_place`.
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/// The `Option<Ty<'tcx>>` is either `Some(T)`, or `None` for empty drop
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/// glue.
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DropGlue(DefId, Option<Ty<'tcx>>),
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/// Compiler-generated `<T as Clone>::clone` implementation.
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///
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/// For all types that automatically implement `Copy`, a trivial `Clone` impl is provided too.
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/// Additionally, arrays, tuples, and closures get a `Clone` shim even if they aren't `Copy`.
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///
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/// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl.
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CloneShim(DefId, Ty<'tcx>),
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/// Compiler-generated `<T as FnPtr>::addr` implementation.
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///
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/// Automatically generated for all potentially higher-ranked `fn(I) -> R` types.
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///
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/// The `DefId` is for `FnPtr::addr`, the `Ty` is the type `T`.
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FnPtrAddrShim(DefId, Ty<'tcx>),
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}
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impl<'tcx> Instance<'tcx> {
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/// Returns the `Ty` corresponding to this `Instance`, with generic substitutions applied and
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/// lifetimes erased, allowing a `ParamEnv` to be specified for use during normalization.
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pub fn ty(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Ty<'tcx> {
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let ty = tcx.type_of(self.def.def_id());
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tcx.instantiate_and_normalize_erasing_regions(self.args, param_env, ty)
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}
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/// Finds a crate that contains a monomorphization of this instance that
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/// can be linked to from the local crate. A return value of `None` means
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/// no upstream crate provides such an exported monomorphization.
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///
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/// This method already takes into account the global `-Zshare-generics`
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/// setting, always returning `None` if `share-generics` is off.
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pub fn upstream_monomorphization(&self, tcx: TyCtxt<'tcx>) -> Option<CrateNum> {
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// If we are not in share generics mode, we don't link to upstream
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// monomorphizations but always instantiate our own internal versions
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// instead.
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if !tcx.sess.opts.share_generics() {
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return None;
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}
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// If this is an item that is defined in the local crate, no upstream
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// crate can know about it/provide a monomorphization.
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if self.def_id().is_local() {
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return None;
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}
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// If this a non-generic instance, it cannot be a shared monomorphization.
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self.args.non_erasable_generics(tcx, self.def_id()).next()?;
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match self.def {
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InstanceDef::Item(def) => tcx
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.upstream_monomorphizations_for(def)
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.and_then(|monos| monos.get(&self.args).cloned()),
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InstanceDef::DropGlue(_, Some(_)) => tcx.upstream_drop_glue_for(self.args),
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_ => None,
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}
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}
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}
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impl<'tcx> InstanceDef<'tcx> {
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#[inline]
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pub fn def_id(self) -> DefId {
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match self {
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InstanceDef::Item(def_id)
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| InstanceDef::VTableShim(def_id)
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| InstanceDef::ReifyShim(def_id)
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| InstanceDef::FnPtrShim(def_id, _)
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| InstanceDef::Virtual(def_id, _)
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| InstanceDef::Intrinsic(def_id)
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| InstanceDef::ThreadLocalShim(def_id)
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| InstanceDef::ClosureOnceShim { call_once: def_id, track_caller: _ }
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| InstanceDef::DropGlue(def_id, _)
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| InstanceDef::CloneShim(def_id, _)
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| InstanceDef::FnPtrAddrShim(def_id, _) => def_id,
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}
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}
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/// Returns the `DefId` of instances which might not require codegen locally.
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pub fn def_id_if_not_guaranteed_local_codegen(self) -> Option<DefId> {
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match self {
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ty::InstanceDef::Item(def) => Some(def),
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ty::InstanceDef::DropGlue(def_id, Some(_)) | InstanceDef::ThreadLocalShim(def_id) => {
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Some(def_id)
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}
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InstanceDef::VTableShim(..)
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| InstanceDef::ReifyShim(..)
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| InstanceDef::FnPtrShim(..)
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| InstanceDef::Virtual(..)
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| InstanceDef::Intrinsic(..)
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| InstanceDef::ClosureOnceShim { .. }
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| InstanceDef::DropGlue(..)
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| InstanceDef::CloneShim(..)
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| InstanceDef::FnPtrAddrShim(..) => None,
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}
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}
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#[inline]
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pub fn get_attrs(
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&self,
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tcx: TyCtxt<'tcx>,
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attr: Symbol,
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) -> impl Iterator<Item = &'tcx rustc_ast::Attribute> {
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tcx.get_attrs(self.def_id(), attr)
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}
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/// Returns `true` if the LLVM version of this instance is unconditionally
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/// marked with `inline`. This implies that a copy of this instance is
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/// generated in every codegen unit.
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/// Note that this is only a hint. See the documentation for
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/// `generates_cgu_internal_copy` for more information.
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pub fn requires_inline(&self, tcx: TyCtxt<'tcx>) -> bool {
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use rustc_hir::definitions::DefPathData;
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let def_id = match *self {
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ty::InstanceDef::Item(def) => def,
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ty::InstanceDef::DropGlue(_, Some(_)) => return false,
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ty::InstanceDef::ThreadLocalShim(_) => return false,
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_ => return true,
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};
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matches!(
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tcx.def_key(def_id).disambiguated_data.data,
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DefPathData::Ctor | DefPathData::ClosureExpr
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)
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}
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/// Returns `true` if the machine code for this instance is instantiated in
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/// each codegen unit that references it.
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/// Note that this is only a hint! The compiler can globally decide to *not*
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/// do this in order to speed up compilation. CGU-internal copies are
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/// only exist to enable inlining. If inlining is not performed (e.g. at
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/// `-Copt-level=0`) then the time for generating them is wasted and it's
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/// better to create a single copy with external linkage.
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pub fn generates_cgu_internal_copy(&self, tcx: TyCtxt<'tcx>) -> bool {
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if self.requires_inline(tcx) {
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return true;
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}
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if let ty::InstanceDef::DropGlue(.., Some(ty)) = *self {
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// Drop glue generally wants to be instantiated at every codegen
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// unit, but without an #[inline] hint. We should make this
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// available to normal end-users.
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if tcx.sess.opts.incremental.is_none() {
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return true;
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}
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// When compiling with incremental, we can generate a *lot* of
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// codegen units. Including drop glue into all of them has a
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// considerable compile time cost.
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//
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// We include enums without destructors to allow, say, optimizing
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// drops of `Option::None` before LTO. We also respect the intent of
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// `#[inline]` on `Drop::drop` implementations.
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return ty.ty_adt_def().map_or(true, |adt_def| {
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adt_def.destructor(tcx).map_or_else(
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|| adt_def.is_enum(),
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|dtor| tcx.codegen_fn_attrs(dtor.did).requests_inline(),
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)
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});
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}
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if let ty::InstanceDef::ThreadLocalShim(..) = *self {
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return false;
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}
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tcx.codegen_fn_attrs(self.def_id()).requests_inline()
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}
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pub fn requires_caller_location(&self, tcx: TyCtxt<'_>) -> bool {
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match *self {
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InstanceDef::Item(def_id) | InstanceDef::Virtual(def_id, _) => {
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tcx.body_codegen_attrs(def_id).flags.contains(CodegenFnAttrFlags::TRACK_CALLER)
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}
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InstanceDef::ClosureOnceShim { call_once: _, track_caller } => track_caller,
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_ => false,
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}
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}
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/// Returns `true` when the MIR body associated with this instance should be monomorphized
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/// by its users (e.g. codegen or miri) by substituting the `args` from `Instance` (see
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/// `Instance::args_for_mir_body`).
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///
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/// Otherwise, returns `false` only for some kinds of shims where the construction of the MIR
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/// body should perform necessary substitutions.
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pub fn has_polymorphic_mir_body(&self) -> bool {
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match *self {
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InstanceDef::CloneShim(..)
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| InstanceDef::ThreadLocalShim(..)
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| InstanceDef::FnPtrAddrShim(..)
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| InstanceDef::FnPtrShim(..)
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| InstanceDef::DropGlue(_, Some(_)) => false,
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InstanceDef::ClosureOnceShim { .. }
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| InstanceDef::DropGlue(..)
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| InstanceDef::Item(_)
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| InstanceDef::Intrinsic(..)
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| InstanceDef::ReifyShim(..)
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| InstanceDef::Virtual(..)
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| InstanceDef::VTableShim(..) => true,
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}
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}
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}
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fn fmt_instance(
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f: &mut fmt::Formatter<'_>,
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instance: &Instance<'_>,
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type_length: rustc_session::Limit,
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) -> fmt::Result {
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ty::tls::with(|tcx| {
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let args = tcx.lift(instance.args).expect("could not lift for printing");
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let s = FmtPrinter::new_with_limit(tcx, Namespace::ValueNS, type_length)
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.print_def_path(instance.def_id(), args)?
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.into_buffer();
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f.write_str(&s)
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})?;
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match instance.def {
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InstanceDef::Item(_) => Ok(()),
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InstanceDef::VTableShim(_) => write!(f, " - shim(vtable)"),
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InstanceDef::ReifyShim(_) => write!(f, " - shim(reify)"),
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InstanceDef::ThreadLocalShim(_) => write!(f, " - shim(tls)"),
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InstanceDef::Intrinsic(_) => write!(f, " - intrinsic"),
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InstanceDef::Virtual(_, num) => write!(f, " - virtual#{num}"),
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InstanceDef::FnPtrShim(_, ty) => write!(f, " - shim({ty})"),
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InstanceDef::ClosureOnceShim { .. } => write!(f, " - shim"),
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InstanceDef::DropGlue(_, None) => write!(f, " - shim(None)"),
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InstanceDef::DropGlue(_, Some(ty)) => write!(f, " - shim(Some({ty}))"),
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InstanceDef::CloneShim(_, ty) => write!(f, " - shim({ty})"),
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InstanceDef::FnPtrAddrShim(_, ty) => write!(f, " - shim({ty})"),
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}
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}
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pub struct ShortInstance<'a, 'tcx>(pub &'a Instance<'tcx>, pub usize);
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impl<'a, 'tcx> fmt::Display for ShortInstance<'a, 'tcx> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt_instance(f, self.0, rustc_session::Limit(self.1))
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}
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}
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impl<'tcx> fmt::Display for Instance<'tcx> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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ty::tls::with(|tcx| fmt_instance(f, self, tcx.type_length_limit()))
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}
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}
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impl<'tcx> Instance<'tcx> {
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pub fn new(def_id: DefId, args: GenericArgsRef<'tcx>) -> Instance<'tcx> {
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assert!(
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!args.has_escaping_bound_vars(),
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"args of instance {def_id:?} not normalized for codegen: {args:?}"
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);
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Instance { def: InstanceDef::Item(def_id), args }
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}
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pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> {
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let args = GenericArgs::for_item(tcx, def_id, |param, _| match param.kind {
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ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
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ty::GenericParamDefKind::Const { is_host_effect: true, .. } => tcx.consts.true_.into(),
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ty::GenericParamDefKind::Type { .. } => {
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bug!("Instance::mono: {:?} has type parameters", def_id)
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}
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ty::GenericParamDefKind::Const { .. } => {
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bug!("Instance::mono: {:?} has const parameters", def_id)
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}
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});
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Instance::new(def_id, args)
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}
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#[inline]
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pub fn def_id(&self) -> DefId {
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self.def.def_id()
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}
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/// Resolves a `(def_id, args)` pair to an (optional) instance -- most commonly,
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/// this is used to find the precise code that will run for a trait method invocation,
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/// if known.
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///
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/// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance.
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/// For example, in a context like this,
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///
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/// ```ignore (illustrative)
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/// fn foo<T: Debug>(t: T) { ... }
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/// ```
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///
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/// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not
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/// know what code ought to run. (Note that this setting is also affected by the
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/// `RevealMode` in the parameter environment.)
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///
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/// Presuming that coherence and type-check have succeeded, if this method is invoked
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/// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return
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/// `Ok(Some(instance))`.
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///
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/// Returns `Err(ErrorGuaranteed)` when the `Instance` resolution process
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/// couldn't complete due to errors elsewhere - this is distinct
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/// from `Ok(None)` to avoid misleading diagnostics when an error
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/// has already been/will be emitted, for the original cause
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#[instrument(level = "debug", skip(tcx), ret)]
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pub fn resolve(
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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def_id: DefId,
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args: GenericArgsRef<'tcx>,
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) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
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// All regions in the result of this query are erased, so it's
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// fine to erase all of the input regions.
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// HACK(eddyb) erase regions in `args` first, so that `param_env.and(...)`
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// below is more likely to ignore the bounds in scope (e.g. if the only
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// generic parameters mentioned by `args` were lifetime ones).
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let args = tcx.erase_regions(args);
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tcx.resolve_instance(tcx.erase_regions(param_env.and((def_id, args))))
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}
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pub fn expect_resolve(
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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def_id: DefId,
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args: GenericArgsRef<'tcx>,
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) -> Instance<'tcx> {
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match ty::Instance::resolve(tcx, param_env, def_id, args) {
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Ok(Some(instance)) => instance,
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instance => bug!(
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"failed to resolve instance for {}: {instance:#?}",
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tcx.def_path_str_with_args(def_id, args)
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),
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}
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}
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pub fn resolve_for_fn_ptr(
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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def_id: DefId,
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args: GenericArgsRef<'tcx>,
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) -> Option<Instance<'tcx>> {
|
|
debug!("resolve(def_id={:?}, args={:?})", def_id, args);
|
|
// Use either `resolve_closure` or `resolve_for_vtable`
|
|
assert!(!tcx.is_closure(def_id), "Called `resolve_for_fn_ptr` on closure: {def_id:?}");
|
|
Instance::resolve(tcx, param_env, def_id, args).ok().flatten().map(|mut resolved| {
|
|
match resolved.def {
|
|
InstanceDef::Item(def) if resolved.def.requires_caller_location(tcx) => {
|
|
debug!(" => fn pointer created for function with #[track_caller]");
|
|
resolved.def = InstanceDef::ReifyShim(def);
|
|
}
|
|
InstanceDef::Virtual(def_id, _) => {
|
|
debug!(" => fn pointer created for virtual call");
|
|
resolved.def = InstanceDef::ReifyShim(def_id);
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
resolved
|
|
})
|
|
}
|
|
|
|
pub fn resolve_for_vtable(
|
|
tcx: TyCtxt<'tcx>,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
def_id: DefId,
|
|
args: GenericArgsRef<'tcx>,
|
|
) -> Option<Instance<'tcx>> {
|
|
debug!("resolve_for_vtable(def_id={:?}, args={:?})", def_id, args);
|
|
let fn_sig = tcx.fn_sig(def_id).instantiate_identity();
|
|
let is_vtable_shim = !fn_sig.inputs().skip_binder().is_empty()
|
|
&& fn_sig.input(0).skip_binder().is_param(0)
|
|
&& tcx.generics_of(def_id).has_self;
|
|
if is_vtable_shim {
|
|
debug!(" => associated item with unsizeable self: Self");
|
|
Some(Instance { def: InstanceDef::VTableShim(def_id), args })
|
|
} else {
|
|
Instance::resolve(tcx, param_env, def_id, args).ok().flatten().map(|mut resolved| {
|
|
match resolved.def {
|
|
InstanceDef::Item(def) => {
|
|
// We need to generate a shim when we cannot guarantee that
|
|
// the caller of a trait object method will be aware of
|
|
// `#[track_caller]` - this ensures that the caller
|
|
// and callee ABI will always match.
|
|
//
|
|
// The shim is generated when all of these conditions are met:
|
|
//
|
|
// 1) The underlying method expects a caller location parameter
|
|
// in the ABI
|
|
if resolved.def.requires_caller_location(tcx)
|
|
// 2) The caller location parameter comes from having `#[track_caller]`
|
|
// on the implementation, and *not* on the trait method.
|
|
&& !tcx.should_inherit_track_caller(def)
|
|
// If the method implementation comes from the trait definition itself
|
|
// (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`),
|
|
// then we don't need to generate a shim. This check is needed because
|
|
// `should_inherit_track_caller` returns `false` if our method
|
|
// implementation comes from the trait block, and not an impl block
|
|
&& !matches!(
|
|
tcx.opt_associated_item(def),
|
|
Some(ty::AssocItem {
|
|
container: ty::AssocItemContainer::TraitContainer,
|
|
..
|
|
})
|
|
)
|
|
{
|
|
if tcx.is_closure(def) {
|
|
debug!(" => vtable fn pointer created for closure with #[track_caller]: {:?} for method {:?} {:?}",
|
|
def, def_id, args);
|
|
|
|
// Create a shim for the `FnOnce/FnMut/Fn` method we are calling
|
|
// - unlike functions, invoking a closure always goes through a
|
|
// trait.
|
|
resolved = Instance { def: InstanceDef::ReifyShim(def_id), args };
|
|
} else {
|
|
debug!(
|
|
" => vtable fn pointer created for function with #[track_caller]: {:?}", def
|
|
);
|
|
resolved.def = InstanceDef::ReifyShim(def);
|
|
}
|
|
}
|
|
}
|
|
InstanceDef::Virtual(def_id, _) => {
|
|
debug!(" => vtable fn pointer created for virtual call");
|
|
resolved.def = InstanceDef::ReifyShim(def_id);
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
resolved
|
|
})
|
|
}
|
|
}
|
|
|
|
pub fn resolve_closure(
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
args: ty::GenericArgsRef<'tcx>,
|
|
requested_kind: ty::ClosureKind,
|
|
) -> Option<Instance<'tcx>> {
|
|
let actual_kind = args.as_closure().kind();
|
|
|
|
match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
|
|
Ok(true) => Instance::fn_once_adapter_instance(tcx, def_id, args),
|
|
_ => Some(Instance::new(def_id, args)),
|
|
}
|
|
}
|
|
|
|
pub fn resolve_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ty::Instance<'tcx> {
|
|
let def_id = tcx.require_lang_item(LangItem::DropInPlace, None);
|
|
let args = tcx.mk_args(&[ty.into()]);
|
|
Instance::expect_resolve(tcx, ty::ParamEnv::reveal_all(), def_id, args)
|
|
}
|
|
|
|
#[instrument(level = "debug", skip(tcx), ret)]
|
|
pub fn fn_once_adapter_instance(
|
|
tcx: TyCtxt<'tcx>,
|
|
closure_did: DefId,
|
|
args: ty::GenericArgsRef<'tcx>,
|
|
) -> Option<Instance<'tcx>> {
|
|
let fn_once = tcx.require_lang_item(LangItem::FnOnce, None);
|
|
let call_once = tcx
|
|
.associated_items(fn_once)
|
|
.in_definition_order()
|
|
.find(|it| it.kind == ty::AssocKind::Fn)
|
|
.unwrap()
|
|
.def_id;
|
|
let track_caller =
|
|
tcx.codegen_fn_attrs(closure_did).flags.contains(CodegenFnAttrFlags::TRACK_CALLER);
|
|
let def = ty::InstanceDef::ClosureOnceShim { call_once, track_caller };
|
|
|
|
let self_ty = Ty::new_closure(tcx, closure_did, args);
|
|
|
|
let sig = args.as_closure().sig();
|
|
let sig =
|
|
tcx.try_normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig).ok()?;
|
|
assert_eq!(sig.inputs().len(), 1);
|
|
let args = tcx.mk_args_trait(self_ty, [sig.inputs()[0].into()]);
|
|
|
|
debug!(?self_ty, ?sig);
|
|
Some(Instance { def, args })
|
|
}
|
|
|
|
/// Depending on the kind of `InstanceDef`, the MIR body associated with an
|
|
/// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other
|
|
/// cases the MIR body is expressed in terms of the types found in the substitution array.
|
|
/// In the former case, we want to substitute those generic types and replace them with the
|
|
/// values from the args when monomorphizing the function body. But in the latter case, we
|
|
/// don't want to do that substitution, since it has already been done effectively.
|
|
///
|
|
/// This function returns `Some(args)` in the former case and `None` otherwise -- i.e., if
|
|
/// this function returns `None`, then the MIR body does not require substitution during
|
|
/// codegen.
|
|
fn args_for_mir_body(&self) -> Option<GenericArgsRef<'tcx>> {
|
|
self.def.has_polymorphic_mir_body().then_some(self.args)
|
|
}
|
|
|
|
pub fn instantiate_mir<T>(&self, tcx: TyCtxt<'tcx>, v: EarlyBinder<&T>) -> T
|
|
where
|
|
T: TypeFoldable<TyCtxt<'tcx>> + Copy,
|
|
{
|
|
let v = v.map_bound(|v| *v);
|
|
if let Some(args) = self.args_for_mir_body() {
|
|
v.instantiate(tcx, args)
|
|
} else {
|
|
v.instantiate_identity()
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
pub fn instantiate_mir_and_normalize_erasing_regions<T>(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
v: EarlyBinder<T>,
|
|
) -> T
|
|
where
|
|
T: TypeFoldable<TyCtxt<'tcx>> + Clone,
|
|
{
|
|
if let Some(args) = self.args_for_mir_body() {
|
|
tcx.instantiate_and_normalize_erasing_regions(args, param_env, v)
|
|
} else {
|
|
tcx.normalize_erasing_regions(param_env, v.skip_binder())
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
pub fn try_instantiate_mir_and_normalize_erasing_regions<T>(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
v: EarlyBinder<T>,
|
|
) -> Result<T, NormalizationError<'tcx>>
|
|
where
|
|
T: TypeFoldable<TyCtxt<'tcx>> + Clone,
|
|
{
|
|
if let Some(args) = self.args_for_mir_body() {
|
|
tcx.try_instantiate_and_normalize_erasing_regions(args, param_env, v)
|
|
} else {
|
|
tcx.try_normalize_erasing_regions(param_env, v.skip_binder())
|
|
}
|
|
}
|
|
|
|
/// Returns a new `Instance` where generic parameters in `instance.args` are replaced by
|
|
/// identity parameters if they are determined to be unused in `instance.def`.
|
|
pub fn polymorphize(self, tcx: TyCtxt<'tcx>) -> Self {
|
|
debug!("polymorphize: running polymorphization analysis");
|
|
if !tcx.sess.opts.unstable_opts.polymorphize {
|
|
return self;
|
|
}
|
|
|
|
let polymorphized_args = polymorphize(tcx, self.def, self.args);
|
|
debug!("polymorphize: self={:?} polymorphized_args={:?}", self, polymorphized_args);
|
|
Self { def: self.def, args: polymorphized_args }
|
|
}
|
|
}
|
|
|
|
fn polymorphize<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
instance: ty::InstanceDef<'tcx>,
|
|
args: GenericArgsRef<'tcx>,
|
|
) -> GenericArgsRef<'tcx> {
|
|
debug!("polymorphize({:?}, {:?})", instance, args);
|
|
let unused = tcx.unused_generic_params(instance);
|
|
debug!("polymorphize: unused={:?}", unused);
|
|
|
|
// If this is a closure or generator then we need to handle the case where another closure
|
|
// from the function is captured as an upvar and hasn't been polymorphized. In this case,
|
|
// the unpolymorphized upvar closure would result in a polymorphized closure producing
|
|
// multiple mono items (and eventually symbol clashes).
|
|
let def_id = instance.def_id();
|
|
let upvars_ty = if tcx.is_closure(def_id) {
|
|
Some(args.as_closure().tupled_upvars_ty())
|
|
} else if tcx.type_of(def_id).skip_binder().is_generator() {
|
|
Some(args.as_generator().tupled_upvars_ty())
|
|
} else {
|
|
None
|
|
};
|
|
let has_upvars = upvars_ty.is_some_and(|ty| !ty.tuple_fields().is_empty());
|
|
debug!("polymorphize: upvars_ty={:?} has_upvars={:?}", upvars_ty, has_upvars);
|
|
|
|
struct PolymorphizationFolder<'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
}
|
|
|
|
impl<'tcx> ty::TypeFolder<TyCtxt<'tcx>> for PolymorphizationFolder<'tcx> {
|
|
fn interner(&self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
debug!("fold_ty: ty={:?}", ty);
|
|
match *ty.kind() {
|
|
ty::Closure(def_id, args) => {
|
|
let polymorphized_args =
|
|
polymorphize(self.tcx, ty::InstanceDef::Item(def_id), args);
|
|
if args == polymorphized_args {
|
|
ty
|
|
} else {
|
|
Ty::new_closure(self.tcx, def_id, polymorphized_args)
|
|
}
|
|
}
|
|
ty::Generator(def_id, args, movability) => {
|
|
let polymorphized_args =
|
|
polymorphize(self.tcx, ty::InstanceDef::Item(def_id), args);
|
|
if args == polymorphized_args {
|
|
ty
|
|
} else {
|
|
Ty::new_generator(self.tcx, def_id, polymorphized_args, movability)
|
|
}
|
|
}
|
|
_ => ty.super_fold_with(self),
|
|
}
|
|
}
|
|
}
|
|
|
|
GenericArgs::for_item(tcx, def_id, |param, _| {
|
|
let is_unused = unused.is_unused(param.index);
|
|
debug!("polymorphize: param={:?} is_unused={:?}", param, is_unused);
|
|
match param.kind {
|
|
// Upvar case: If parameter is a type parameter..
|
|
ty::GenericParamDefKind::Type { .. } if
|
|
// ..and has upvars..
|
|
has_upvars &&
|
|
// ..and this param has the same type as the tupled upvars..
|
|
upvars_ty == Some(args[param.index as usize].expect_ty()) => {
|
|
// ..then double-check that polymorphization marked it used..
|
|
debug_assert!(!is_unused);
|
|
// ..and polymorphize any closures/generators captured as upvars.
|
|
let upvars_ty = upvars_ty.unwrap();
|
|
let polymorphized_upvars_ty = upvars_ty.fold_with(
|
|
&mut PolymorphizationFolder { tcx });
|
|
debug!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty);
|
|
ty::GenericArg::from(polymorphized_upvars_ty)
|
|
},
|
|
|
|
// Simple case: If parameter is a const or type parameter..
|
|
ty::GenericParamDefKind::Const { .. } | ty::GenericParamDefKind::Type { .. } if
|
|
// ..and is within range and unused..
|
|
unused.is_unused(param.index) =>
|
|
// ..then use the identity for this parameter.
|
|
tcx.mk_param_from_def(param),
|
|
|
|
// Otherwise, use the parameter as before.
|
|
_ => args[param.index as usize],
|
|
}
|
|
})
|
|
}
|
|
|
|
fn needs_fn_once_adapter_shim(
|
|
actual_closure_kind: ty::ClosureKind,
|
|
trait_closure_kind: ty::ClosureKind,
|
|
) -> Result<bool, ()> {
|
|
match (actual_closure_kind, trait_closure_kind) {
|
|
(ty::ClosureKind::Fn, ty::ClosureKind::Fn)
|
|
| (ty::ClosureKind::FnMut, ty::ClosureKind::FnMut)
|
|
| (ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => {
|
|
// No adapter needed.
|
|
Ok(false)
|
|
}
|
|
(ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => {
|
|
// The closure fn `llfn` is a `fn(&self, ...)`. We want a
|
|
// `fn(&mut self, ...)`. In fact, at codegen time, these are
|
|
// basically the same thing, so we can just return llfn.
|
|
Ok(false)
|
|
}
|
|
(ty::ClosureKind::Fn | ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => {
|
|
// The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
|
|
// self, ...)`. We want a `fn(self, ...)`. We can produce
|
|
// this by doing something like:
|
|
//
|
|
// fn call_once(self, ...) { call_mut(&self, ...) }
|
|
// fn call_once(mut self, ...) { call_mut(&mut self, ...) }
|
|
//
|
|
// These are both the same at codegen time.
|
|
Ok(true)
|
|
}
|
|
(ty::ClosureKind::FnMut | ty::ClosureKind::FnOnce, _) => Err(()),
|
|
}
|
|
}
|
|
|
|
// Set bits represent unused generic parameters.
|
|
// An empty set indicates that all parameters are used.
|
|
#[derive(Debug, Copy, Clone, Eq, PartialEq, Decodable, Encodable, HashStable)]
|
|
pub struct UnusedGenericParams(FiniteBitSet<u32>);
|
|
|
|
impl Default for UnusedGenericParams {
|
|
fn default() -> Self {
|
|
UnusedGenericParams::new_all_used()
|
|
}
|
|
}
|
|
|
|
impl UnusedGenericParams {
|
|
pub fn new_all_unused(amount: u32) -> Self {
|
|
let mut bitset = FiniteBitSet::new_empty();
|
|
bitset.set_range(0..amount);
|
|
Self(bitset)
|
|
}
|
|
|
|
pub fn new_all_used() -> Self {
|
|
Self(FiniteBitSet::new_empty())
|
|
}
|
|
|
|
pub fn mark_used(&mut self, idx: u32) {
|
|
self.0.clear(idx);
|
|
}
|
|
|
|
pub fn is_unused(&self, idx: u32) -> bool {
|
|
self.0.contains(idx).unwrap_or(false)
|
|
}
|
|
|
|
pub fn is_used(&self, idx: u32) -> bool {
|
|
!self.is_unused(idx)
|
|
}
|
|
|
|
pub fn all_used(&self) -> bool {
|
|
self.0.is_empty()
|
|
}
|
|
|
|
pub fn bits(&self) -> u32 {
|
|
self.0.0
|
|
}
|
|
|
|
pub fn from_bits(bits: u32) -> UnusedGenericParams {
|
|
UnusedGenericParams(FiniteBitSet(bits))
|
|
}
|
|
}
|