1059 lines
44 KiB
Rust
1059 lines
44 KiB
Rust
use std::assert_matches::assert_matches;
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use std::fmt;
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use std::path::PathBuf;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_errors::ErrorGuaranteed;
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use rustc_hir as hir;
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use rustc_hir::def::{CtorKind, DefKind, 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::{Decodable, Encodable, HashStable, Lift, TyDecodable, TyEncodable};
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use rustc_span::def_id::LOCAL_CRATE;
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use rustc_span::{DUMMY_SP, Span, Symbol};
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use tracing::{debug, instrument};
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use crate::error;
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use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
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use crate::ty::normalize_erasing_regions::NormalizationError;
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use crate::ty::print::{FmtPrinter, Printer, shrunk_instance_name};
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use crate::ty::{
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self, EarlyBinder, GenericArgs, GenericArgsRef, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
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TypeVisitable, TypeVisitableExt, TypeVisitor,
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};
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/// An `InstanceKind` along with the args that are needed to substitute the instance.
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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 `InstanceKind` with some args, and codegen and const eval
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/// will do all required instantiations 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: InstanceKind<'tcx>,
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pub args: GenericArgsRef<'tcx>,
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}
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/// Describes why a `ReifyShim` was created. This is needed to distinguish a ReifyShim created to
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/// adjust for things like `#[track_caller]` in a vtable from a `ReifyShim` created to produce a
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/// function pointer from a vtable entry.
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/// Currently, this is only used when KCFI is enabled, as only KCFI needs to treat those two
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/// `ReifyShim`s differently.
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#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
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#[derive(TyEncodable, TyDecodable, HashStable)]
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pub enum ReifyReason {
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/// The `ReifyShim` was created to produce a function pointer. This happens when:
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/// * A vtable entry is directly converted to a function call (e.g. creating a fn ptr from a
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/// method on a `dyn` object).
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/// * A function with `#[track_caller]` is converted to a function pointer
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/// * If KCFI is enabled, creating a function pointer from a method on a dyn-compatible trait.
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/// This includes the case of converting `::call`-like methods on closure-likes to function
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/// pointers.
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FnPtr,
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/// This `ReifyShim` was created to populate a vtable. Currently, this happens when a
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/// `#[track_caller]` mismatch occurs between the implementation of a method and the method.
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/// This includes the case of `::call`-like methods in closure-likes' vtables.
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Vtable,
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}
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#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
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#[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable, Lift)]
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pub enum InstanceKind<'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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/// - coroutines
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Item(DefId),
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/// An intrinsic `fn` item (with`#[rustc_instrinsic]`).
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///
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/// Alongside `Virtual`, this is the only `InstanceKind` 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 `InstanceKind::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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///
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/// The second field encodes *why* this shim was created. This allows distinguishing between
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/// a `ReifyShim` that appears in a vtable vs one that appears as a function pointer.
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///
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/// This field will only be populated if we are compiling in a mode that needs these shims
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/// to be separable, currently only when KCFI is enabled.
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ReifyShim(DefId, Option<ReifyReason>),
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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 `InstanceKind` may have a callable MIR as the default implementation.
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/// Calls to `Virtual` instances must be codegen'd as virtual calls through the vtable.
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/// *This means we might not know exactly what is being called.*
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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/Fn 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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///
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/// This generates a body that will just borrow the (owned) self type,
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/// and dispatch to the `FnMut::call_mut` instance for the closure.
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ClosureOnceShim { call_once: DefId, track_caller: bool },
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/// `<[FnMut/Fn coroutine-closure] as FnOnce>::call_once`
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///
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/// The body generated here differs significantly from the `ClosureOnceShim`,
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/// since we need to generate a distinct coroutine type that will move the
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/// closure's upvars *out* of the closure.
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ConstructCoroutineInClosureShim {
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coroutine_closure_def_id: DefId,
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// Whether the generated MIR body takes the coroutine by-ref. This is
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// because the signature of `<{async fn} as FnMut>::call_mut` is:
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// `fn(&mut self, args: A) -> <Self as FnOnce>::Output`, that is to say
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// that it returns the `FnOnce`-flavored coroutine but takes the closure
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// by mut ref (and similarly for `Fn::call`).
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receiver_by_ref: bool,
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},
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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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/// Proxy shim for async drop of future (def_id, proxy_cor_ty, impl_cor_ty)
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FutureDropPollShim(DefId, Ty<'tcx>, Ty<'tcx>),
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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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/// `core::future::async_drop::async_drop_in_place::<'_, T>`.
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///
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/// The `DefId` is for `core::future::async_drop::async_drop_in_place`, the `Ty`
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/// is the type `T`.
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AsyncDropGlueCtorShim(DefId, Ty<'tcx>),
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/// `core::future::async_drop::async_drop_in_place::<'_, T>::{closure}`.
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///
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/// async_drop_in_place poll function implementation (for generated coroutine).
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/// `Ty` here is `async_drop_in_place<T>::{closure}` coroutine type, not just `T`
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AsyncDropGlue(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 instantiations 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>, typing_env: ty::TypingEnv<'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, typing_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 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 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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// However, if the def_id is marked inline(never), then it's fine to just reuse the
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// upstream monomorphization.
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&& tcx.codegen_fn_attrs(self.def_id()).inline != rustc_attr_data_structures::InlineAttr::Never
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{
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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().next()?;
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// compiler_builtins cannot use upstream monomorphizations.
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if tcx.is_compiler_builtins(LOCAL_CRATE) {
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return None;
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}
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match self.def {
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InstanceKind::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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InstanceKind::DropGlue(_, Some(_)) => tcx.upstream_drop_glue_for(self.args),
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InstanceKind::AsyncDropGlue(_, _) => None,
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InstanceKind::FutureDropPollShim(_, _, _) => None,
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InstanceKind::AsyncDropGlueCtorShim(_, _) => {
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tcx.upstream_async_drop_glue_for(self.args)
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}
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_ => None,
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}
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}
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}
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impl<'tcx> InstanceKind<'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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InstanceKind::Item(def_id)
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| InstanceKind::VTableShim(def_id)
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| InstanceKind::ReifyShim(def_id, _)
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| InstanceKind::FnPtrShim(def_id, _)
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| InstanceKind::Virtual(def_id, _)
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| InstanceKind::Intrinsic(def_id)
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| InstanceKind::ThreadLocalShim(def_id)
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| InstanceKind::ClosureOnceShim { call_once: def_id, track_caller: _ }
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| ty::InstanceKind::ConstructCoroutineInClosureShim {
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coroutine_closure_def_id: def_id,
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receiver_by_ref: _,
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}
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| InstanceKind::DropGlue(def_id, _)
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| InstanceKind::CloneShim(def_id, _)
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| InstanceKind::FnPtrAddrShim(def_id, _)
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| InstanceKind::FutureDropPollShim(def_id, _, _)
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| InstanceKind::AsyncDropGlue(def_id, _)
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| InstanceKind::AsyncDropGlueCtorShim(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::InstanceKind::Item(def) => Some(def),
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ty::InstanceKind::DropGlue(def_id, Some(_))
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| InstanceKind::AsyncDropGlueCtorShim(def_id, _)
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| InstanceKind::AsyncDropGlue(def_id, _)
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| InstanceKind::FutureDropPollShim(def_id, ..)
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| InstanceKind::ThreadLocalShim(def_id) => Some(def_id),
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InstanceKind::VTableShim(..)
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| InstanceKind::ReifyShim(..)
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| InstanceKind::FnPtrShim(..)
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| InstanceKind::Virtual(..)
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| InstanceKind::Intrinsic(..)
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| InstanceKind::ClosureOnceShim { .. }
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| ty::InstanceKind::ConstructCoroutineInClosureShim { .. }
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| InstanceKind::DropGlue(..)
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| InstanceKind::CloneShim(..)
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| InstanceKind::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 hir::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::InstanceKind::Item(def) => def,
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ty::InstanceKind::DropGlue(_, Some(_)) => return false,
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ty::InstanceKind::AsyncDropGlueCtorShim(_, ty) => return ty.is_coroutine(),
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ty::InstanceKind::FutureDropPollShim(_, _, _) => return false,
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ty::InstanceKind::AsyncDropGlue(_, _) => return false,
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ty::InstanceKind::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::Closure
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)
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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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InstanceKind::Item(def_id) | InstanceKind::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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InstanceKind::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 instantiating 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 instantiations.
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pub fn has_polymorphic_mir_body(&self) -> bool {
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match *self {
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|
InstanceKind::CloneShim(..)
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| InstanceKind::ThreadLocalShim(..)
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| InstanceKind::FnPtrAddrShim(..)
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| InstanceKind::FnPtrShim(..)
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| InstanceKind::DropGlue(_, Some(_))
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| InstanceKind::FutureDropPollShim(..)
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| InstanceKind::AsyncDropGlue(_, _) => false,
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InstanceKind::AsyncDropGlueCtorShim(_, _) => false,
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InstanceKind::ClosureOnceShim { .. }
|
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| InstanceKind::ConstructCoroutineInClosureShim { .. }
|
|
| InstanceKind::DropGlue(..)
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| InstanceKind::Item(_)
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|
| InstanceKind::Intrinsic(..)
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| InstanceKind::ReifyShim(..)
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| InstanceKind::Virtual(..)
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| InstanceKind::VTableShim(..) => true,
|
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}
|
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}
|
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}
|
|
|
|
fn type_length<'tcx>(item: impl TypeVisitable<TyCtxt<'tcx>>) -> usize {
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struct Visitor<'tcx> {
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type_length: usize,
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cache: FxHashMap<Ty<'tcx>, usize>,
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}
|
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impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for Visitor<'tcx> {
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|
fn visit_ty(&mut self, t: Ty<'tcx>) {
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if let Some(&value) = self.cache.get(&t) {
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self.type_length += value;
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return;
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}
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|
|
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let prev = self.type_length;
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self.type_length += 1;
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t.super_visit_with(self);
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|
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// We don't try to use the cache if the type is fairly small.
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if self.type_length > 16 {
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self.cache.insert(t, self.type_length - prev);
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}
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}
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|
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fn visit_const(&mut self, ct: ty::Const<'tcx>) {
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self.type_length += 1;
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ct.super_visit_with(self);
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}
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}
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let mut visitor = Visitor { type_length: 0, cache: Default::default() };
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item.visit_with(&mut visitor);
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visitor.type_length
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}
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|
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pub fn fmt_instance(
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f: &mut fmt::Formatter<'_>,
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instance: Instance<'_>,
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type_length: Option<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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|
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let mut cx = if let Some(type_length) = type_length {
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FmtPrinter::new_with_limit(tcx, Namespace::ValueNS, type_length)
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} else {
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FmtPrinter::new(tcx, Namespace::ValueNS)
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|
};
|
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cx.print_def_path(instance.def_id(), args)?;
|
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let s = cx.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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InstanceKind::Item(_) => Ok(()),
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|
InstanceKind::VTableShim(_) => write!(f, " - shim(vtable)"),
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InstanceKind::ReifyShim(_, None) => write!(f, " - shim(reify)"),
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InstanceKind::ReifyShim(_, Some(ReifyReason::FnPtr)) => write!(f, " - shim(reify-fnptr)"),
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InstanceKind::ReifyShim(_, Some(ReifyReason::Vtable)) => write!(f, " - shim(reify-vtable)"),
|
|
InstanceKind::ThreadLocalShim(_) => write!(f, " - shim(tls)"),
|
|
InstanceKind::Intrinsic(_) => write!(f, " - intrinsic"),
|
|
InstanceKind::Virtual(_, num) => write!(f, " - virtual#{num}"),
|
|
InstanceKind::FnPtrShim(_, ty) => write!(f, " - shim({ty})"),
|
|
InstanceKind::ClosureOnceShim { .. } => write!(f, " - shim"),
|
|
InstanceKind::ConstructCoroutineInClosureShim { .. } => write!(f, " - shim"),
|
|
InstanceKind::DropGlue(_, None) => write!(f, " - shim(None)"),
|
|
InstanceKind::DropGlue(_, Some(ty)) => write!(f, " - shim(Some({ty}))"),
|
|
InstanceKind::CloneShim(_, ty) => write!(f, " - shim({ty})"),
|
|
InstanceKind::FnPtrAddrShim(_, ty) => write!(f, " - shim({ty})"),
|
|
InstanceKind::FutureDropPollShim(_, proxy_ty, impl_ty) => {
|
|
write!(f, " - dropshim({proxy_ty}-{impl_ty})")
|
|
}
|
|
InstanceKind::AsyncDropGlue(_, ty) => write!(f, " - shim({ty})"),
|
|
InstanceKind::AsyncDropGlueCtorShim(_, ty) => write!(f, " - shim(Some({ty}))"),
|
|
}
|
|
}
|
|
|
|
pub struct ShortInstance<'tcx>(pub Instance<'tcx>, pub usize);
|
|
|
|
impl<'tcx> fmt::Display for ShortInstance<'tcx> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt_instance(f, self.0, Some(rustc_session::Limit(self.1)))
|
|
}
|
|
}
|
|
|
|
impl<'tcx> fmt::Display for Instance<'tcx> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt_instance(f, *self, None)
|
|
}
|
|
}
|
|
|
|
// async_drop_in_place<T>::coroutine.poll, when T is a standart coroutine,
|
|
// should be resolved to this coroutine's future_drop_poll (through FutureDropPollShim proxy).
|
|
// async_drop_in_place<async_drop_in_place<T>::coroutine>::coroutine.poll,
|
|
// when T is a standart coroutine, should be resolved to this coroutine's future_drop_poll.
|
|
// async_drop_in_place<async_drop_in_place<T>::coroutine>::coroutine.poll,
|
|
// when T is not a coroutine, should be resolved to the innermost
|
|
// async_drop_in_place<T>::coroutine's poll function (through FutureDropPollShim proxy)
|
|
fn resolve_async_drop_poll<'tcx>(mut cor_ty: Ty<'tcx>) -> Instance<'tcx> {
|
|
let first_cor = cor_ty;
|
|
let ty::Coroutine(poll_def_id, proxy_args) = first_cor.kind() else {
|
|
bug!();
|
|
};
|
|
let poll_def_id = *poll_def_id;
|
|
let mut child_ty = cor_ty;
|
|
loop {
|
|
if let ty::Coroutine(child_def, child_args) = child_ty.kind() {
|
|
cor_ty = child_ty;
|
|
if *child_def == poll_def_id {
|
|
child_ty = child_args.first().unwrap().expect_ty();
|
|
continue;
|
|
} else {
|
|
return Instance {
|
|
def: ty::InstanceKind::FutureDropPollShim(poll_def_id, first_cor, cor_ty),
|
|
args: proxy_args,
|
|
};
|
|
}
|
|
} else {
|
|
let ty::Coroutine(_, child_args) = cor_ty.kind() else {
|
|
bug!();
|
|
};
|
|
if first_cor != cor_ty {
|
|
return Instance {
|
|
def: ty::InstanceKind::FutureDropPollShim(poll_def_id, first_cor, cor_ty),
|
|
args: proxy_args,
|
|
};
|
|
} else {
|
|
return Instance {
|
|
def: ty::InstanceKind::AsyncDropGlue(poll_def_id, cor_ty),
|
|
args: child_args,
|
|
};
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Instance<'tcx> {
|
|
/// Creates a new [`InstanceKind::Item`] from the `def_id` and `args`.
|
|
///
|
|
/// Note that this item corresponds to the body of `def_id` directly, which
|
|
/// likely does not make sense for trait items which need to be resolved to an
|
|
/// implementation, and which may not even have a body themselves. Usages of
|
|
/// this function should probably use [`Instance::expect_resolve`], or if run
|
|
/// in a polymorphic environment or within a lint (that may encounter ambiguity)
|
|
/// [`Instance::try_resolve`] instead.
|
|
pub fn new_raw(def_id: DefId, args: GenericArgsRef<'tcx>) -> Instance<'tcx> {
|
|
assert!(
|
|
!args.has_escaping_bound_vars(),
|
|
"args of instance {def_id:?} has escaping bound vars: {args:?}"
|
|
);
|
|
Instance { def: InstanceKind::Item(def_id), args }
|
|
}
|
|
|
|
pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> {
|
|
let args = GenericArgs::for_item(tcx, def_id, |param, _| match param.kind {
|
|
ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
|
|
ty::GenericParamDefKind::Type { .. } => {
|
|
bug!("Instance::mono: {:?} has type parameters", def_id)
|
|
}
|
|
ty::GenericParamDefKind::Const { .. } => {
|
|
bug!("Instance::mono: {:?} has const parameters", def_id)
|
|
}
|
|
});
|
|
|
|
Instance::new_raw(def_id, args)
|
|
}
|
|
|
|
#[inline]
|
|
pub fn def_id(&self) -> DefId {
|
|
self.def.def_id()
|
|
}
|
|
|
|
/// Resolves a `(def_id, args)` pair to an (optional) instance -- most commonly,
|
|
/// this is used to find the precise code that will run for a trait method invocation,
|
|
/// if known. This should only be used for functions and consts. If you want to
|
|
/// resolve an associated type, use [`TyCtxt::try_normalize_erasing_regions`].
|
|
///
|
|
/// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance.
|
|
/// For example, in a context like this,
|
|
///
|
|
/// ```ignore (illustrative)
|
|
/// fn foo<T: Debug>(t: T) { ... }
|
|
/// ```
|
|
///
|
|
/// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not
|
|
/// know what code ought to run. This setting is also affected by the current `TypingMode`
|
|
/// of the environment.
|
|
///
|
|
/// Presuming that coherence and type-check have succeeded, if this method is invoked
|
|
/// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return
|
|
/// `Ok(Some(instance))`, **except** for when the instance's inputs hit the type size limit,
|
|
/// in which case it may bail out and return `Ok(None)`.
|
|
///
|
|
/// Returns `Err(ErrorGuaranteed)` when the `Instance` resolution process
|
|
/// couldn't complete due to errors elsewhere - this is distinct
|
|
/// from `Ok(None)` to avoid misleading diagnostics when an error
|
|
/// has already been/will be emitted, for the original cause
|
|
#[instrument(level = "debug", skip(tcx), ret)]
|
|
pub fn try_resolve(
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
def_id: DefId,
|
|
args: GenericArgsRef<'tcx>,
|
|
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
|
|
assert_matches!(
|
|
tcx.def_kind(def_id),
|
|
DefKind::Fn
|
|
| DefKind::AssocFn
|
|
| DefKind::Const
|
|
| DefKind::AssocConst
|
|
| DefKind::AnonConst
|
|
| DefKind::InlineConst
|
|
| DefKind::Static { .. }
|
|
| DefKind::Ctor(_, CtorKind::Fn)
|
|
| DefKind::Closure
|
|
| DefKind::SyntheticCoroutineBody,
|
|
"`Instance::try_resolve` should only be used to resolve instances of \
|
|
functions, statics, and consts; to resolve associated types, use \
|
|
`try_normalize_erasing_regions`."
|
|
);
|
|
|
|
// Rust code can easily create exponentially-long types using only a
|
|
// polynomial recursion depth. Even with the default recursion
|
|
// depth, you can easily get cases that take >2^60 steps to run,
|
|
// which means that rustc basically hangs.
|
|
//
|
|
// Bail out in these cases to avoid that bad user experience.
|
|
if tcx.sess.opts.unstable_opts.enforce_type_length_limit
|
|
&& !tcx.type_length_limit().value_within_limit(type_length(args))
|
|
{
|
|
return Ok(None);
|
|
}
|
|
|
|
// All regions in the result of this query are erased, so it's
|
|
// fine to erase all of the input regions.
|
|
tcx.resolve_instance_raw(tcx.erase_regions(typing_env.as_query_input((def_id, args))))
|
|
}
|
|
|
|
pub fn expect_resolve(
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
def_id: DefId,
|
|
args: GenericArgsRef<'tcx>,
|
|
span: Span,
|
|
) -> Instance<'tcx> {
|
|
// We compute the span lazily, to avoid unnecessary query calls.
|
|
// If `span` is a DUMMY_SP, and the def id is local, then use the
|
|
// def span of the def id.
|
|
let span_or_local_def_span =
|
|
|| if span.is_dummy() && def_id.is_local() { tcx.def_span(def_id) } else { span };
|
|
|
|
match ty::Instance::try_resolve(tcx, typing_env, def_id, args) {
|
|
Ok(Some(instance)) => instance,
|
|
Ok(None) => {
|
|
let type_length = type_length(args);
|
|
if !tcx.type_length_limit().value_within_limit(type_length) {
|
|
let (shrunk, written_to_path) =
|
|
shrunk_instance_name(tcx, Instance::new_raw(def_id, args));
|
|
let mut path = PathBuf::new();
|
|
let was_written = if let Some(path2) = written_to_path {
|
|
path = path2;
|
|
true
|
|
} else {
|
|
false
|
|
};
|
|
tcx.dcx().emit_fatal(error::TypeLengthLimit {
|
|
// We don't use `def_span(def_id)` so that diagnostics point
|
|
// to the crate root during mono instead of to foreign items.
|
|
// This is arguably better.
|
|
span: span_or_local_def_span(),
|
|
shrunk,
|
|
was_written,
|
|
path,
|
|
type_length,
|
|
});
|
|
} else {
|
|
span_bug!(
|
|
span_or_local_def_span(),
|
|
"failed to resolve instance for {}",
|
|
tcx.def_path_str_with_args(def_id, args)
|
|
)
|
|
}
|
|
}
|
|
instance => span_bug!(
|
|
span_or_local_def_span(),
|
|
"failed to resolve instance for {}: {instance:#?}",
|
|
tcx.def_path_str_with_args(def_id, args)
|
|
),
|
|
}
|
|
}
|
|
|
|
pub fn resolve_for_fn_ptr(
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
def_id: DefId,
|
|
args: GenericArgsRef<'tcx>,
|
|
) -> Option<Instance<'tcx>> {
|
|
debug!("resolve(def_id={:?}, args={:?})", def_id, args);
|
|
// Use either `resolve_closure` or `resolve_for_vtable`
|
|
assert!(!tcx.is_closure_like(def_id), "Called `resolve_for_fn_ptr` on closure: {def_id:?}");
|
|
let reason = tcx.sess.is_sanitizer_kcfi_enabled().then_some(ReifyReason::FnPtr);
|
|
Instance::try_resolve(tcx, typing_env, def_id, args).ok().flatten().map(|mut resolved| {
|
|
match resolved.def {
|
|
InstanceKind::Item(def) if resolved.def.requires_caller_location(tcx) => {
|
|
debug!(" => fn pointer created for function with #[track_caller]");
|
|
resolved.def = InstanceKind::ReifyShim(def, reason);
|
|
}
|
|
InstanceKind::Virtual(def_id, _) => {
|
|
debug!(" => fn pointer created for virtual call");
|
|
resolved.def = InstanceKind::ReifyShim(def_id, reason);
|
|
}
|
|
// Reify `Trait::method` implementations if KCFI is enabled
|
|
// FIXME(maurer) only reify it if it is a vtable-safe function
|
|
_ if tcx.sess.is_sanitizer_kcfi_enabled()
|
|
&& tcx
|
|
.opt_associated_item(def_id)
|
|
.and_then(|assoc| assoc.trait_item_def_id)
|
|
.is_some() =>
|
|
{
|
|
// If this function could also go in a vtable, we need to `ReifyShim` it with
|
|
// KCFI because it can only attach one type per function.
|
|
resolved.def = InstanceKind::ReifyShim(resolved.def_id(), reason)
|
|
}
|
|
// Reify `::call`-like method implementations if KCFI is enabled
|
|
_ if tcx.sess.is_sanitizer_kcfi_enabled()
|
|
&& tcx.is_closure_like(resolved.def_id()) =>
|
|
{
|
|
// Reroute through a reify via the *unresolved* instance. The resolved one can't
|
|
// be directly reified because it's closure-like. The reify can handle the
|
|
// unresolved instance.
|
|
resolved = Instance { def: InstanceKind::ReifyShim(def_id, reason), args }
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
resolved
|
|
})
|
|
}
|
|
|
|
pub fn expect_resolve_for_vtable(
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
def_id: DefId,
|
|
args: GenericArgsRef<'tcx>,
|
|
span: Span,
|
|
) -> 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");
|
|
return Instance { def: InstanceKind::VTableShim(def_id), args };
|
|
}
|
|
|
|
let mut resolved = Instance::expect_resolve(tcx, typing_env, def_id, args, span);
|
|
|
|
let reason = tcx.sess.is_sanitizer_kcfi_enabled().then_some(ReifyReason::Vtable);
|
|
match resolved.def {
|
|
InstanceKind::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
|
|
let needs_track_caller_shim = 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::Trait,
|
|
..
|
|
})
|
|
);
|
|
if needs_track_caller_shim {
|
|
if tcx.is_closure_like(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: InstanceKind::ReifyShim(def_id, reason), args };
|
|
} else {
|
|
debug!(
|
|
" => vtable fn pointer created for function with #[track_caller]: {:?}",
|
|
def
|
|
);
|
|
resolved.def = InstanceKind::ReifyShim(def, reason);
|
|
}
|
|
}
|
|
}
|
|
InstanceKind::Virtual(def_id, _) => {
|
|
debug!(" => vtable fn pointer created for virtual call");
|
|
resolved.def = InstanceKind::ReifyShim(def_id, reason)
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
resolved
|
|
}
|
|
|
|
pub fn resolve_closure(
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
args: ty::GenericArgsRef<'tcx>,
|
|
requested_kind: ty::ClosureKind,
|
|
) -> 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),
|
|
_ => Instance::new_raw(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::TypingEnv::fully_monomorphized(),
|
|
def_id,
|
|
args,
|
|
ty.ty_adt_def().and_then(|adt| tcx.hir_span_if_local(adt.did())).unwrap_or(DUMMY_SP),
|
|
)
|
|
}
|
|
|
|
pub fn resolve_async_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ty::Instance<'tcx> {
|
|
let def_id = tcx.require_lang_item(LangItem::AsyncDropInPlace, None);
|
|
let args = tcx.mk_args(&[ty.into()]);
|
|
Instance::expect_resolve(
|
|
tcx,
|
|
ty::TypingEnv::fully_monomorphized(),
|
|
def_id,
|
|
args,
|
|
ty.ty_adt_def().and_then(|adt| tcx.hir_span_if_local(adt.did())).unwrap_or(DUMMY_SP),
|
|
)
|
|
}
|
|
|
|
pub fn resolve_async_drop_in_place_poll(
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
ty: Ty<'tcx>,
|
|
) -> ty::Instance<'tcx> {
|
|
let args = tcx.mk_args(&[ty.into()]);
|
|
Instance::expect_resolve(tcx, ty::TypingEnv::fully_monomorphized(), def_id, args, DUMMY_SP)
|
|
}
|
|
|
|
#[instrument(level = "debug", skip(tcx), ret)]
|
|
pub fn fn_once_adapter_instance(
|
|
tcx: TyCtxt<'tcx>,
|
|
closure_did: DefId,
|
|
args: ty::GenericArgsRef<'tcx>,
|
|
) -> 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.is_fn())
|
|
.unwrap()
|
|
.def_id;
|
|
let track_caller =
|
|
tcx.codegen_fn_attrs(closure_did).flags.contains(CodegenFnAttrFlags::TRACK_CALLER);
|
|
let def = ty::InstanceKind::ClosureOnceShim { call_once, track_caller };
|
|
|
|
let self_ty = Ty::new_closure(tcx, closure_did, args);
|
|
|
|
let tupled_inputs_ty = args.as_closure().sig().map_bound(|sig| sig.inputs()[0]);
|
|
let tupled_inputs_ty = tcx.instantiate_bound_regions_with_erased(tupled_inputs_ty);
|
|
let args = tcx.mk_args_trait(self_ty, [tupled_inputs_ty.into()]);
|
|
|
|
debug!(?self_ty, args=?tupled_inputs_ty.tuple_fields());
|
|
Instance { def, args }
|
|
}
|
|
|
|
pub fn try_resolve_item_for_coroutine(
|
|
tcx: TyCtxt<'tcx>,
|
|
trait_item_id: DefId,
|
|
trait_id: DefId,
|
|
rcvr_args: ty::GenericArgsRef<'tcx>,
|
|
) -> Option<Instance<'tcx>> {
|
|
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
|
|
return None;
|
|
};
|
|
let coroutine_kind = tcx.coroutine_kind(coroutine_def_id).unwrap();
|
|
|
|
let coroutine_callable_item = if tcx.is_lang_item(trait_id, LangItem::Future) {
|
|
assert_matches!(
|
|
coroutine_kind,
|
|
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)
|
|
);
|
|
hir::LangItem::FuturePoll
|
|
} else if tcx.is_lang_item(trait_id, LangItem::Iterator) {
|
|
assert_matches!(
|
|
coroutine_kind,
|
|
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)
|
|
);
|
|
hir::LangItem::IteratorNext
|
|
} else if tcx.is_lang_item(trait_id, LangItem::AsyncIterator) {
|
|
assert_matches!(
|
|
coroutine_kind,
|
|
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)
|
|
);
|
|
hir::LangItem::AsyncIteratorPollNext
|
|
} else if tcx.is_lang_item(trait_id, LangItem::Coroutine) {
|
|
assert_matches!(coroutine_kind, hir::CoroutineKind::Coroutine(_));
|
|
hir::LangItem::CoroutineResume
|
|
} else {
|
|
return None;
|
|
};
|
|
|
|
if tcx.is_lang_item(trait_item_id, coroutine_callable_item) {
|
|
if tcx.is_async_drop_in_place_coroutine(coroutine_def_id) {
|
|
return Some(resolve_async_drop_poll(rcvr_args.type_at(0)));
|
|
}
|
|
let ty::Coroutine(_, id_args) = *tcx.type_of(coroutine_def_id).skip_binder().kind()
|
|
else {
|
|
bug!()
|
|
};
|
|
|
|
// If the closure's kind ty disagrees with the identity closure's kind ty,
|
|
// then this must be a coroutine generated by one of the `ConstructCoroutineInClosureShim`s.
|
|
if args.as_coroutine().kind_ty() == id_args.as_coroutine().kind_ty() {
|
|
Some(Instance { def: ty::InstanceKind::Item(coroutine_def_id), args })
|
|
} else {
|
|
Some(Instance {
|
|
def: ty::InstanceKind::Item(
|
|
tcx.coroutine_by_move_body_def_id(coroutine_def_id),
|
|
),
|
|
args,
|
|
})
|
|
}
|
|
} else {
|
|
// All other methods should be defaulted methods of the built-in trait.
|
|
// This is important for `Iterator`'s combinators, but also useful for
|
|
// adding future default methods to `Future`, for instance.
|
|
debug_assert!(tcx.defaultness(trait_item_id).has_value());
|
|
Some(Instance::new_raw(trait_item_id, rcvr_args))
|
|
}
|
|
}
|
|
|
|
/// Depending on the kind of `InstanceKind`, 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 generic parameter array.
|
|
/// In the former case, we want to instantiate 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 instantiation, 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 instantiation 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<'tcx, &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)]
|
|
// Keep me in sync with try_instantiate_mir_and_normalize_erasing_regions
|
|
pub fn instantiate_mir_and_normalize_erasing_regions<T>(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
v: EarlyBinder<'tcx, T>,
|
|
) -> T
|
|
where
|
|
T: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
if let Some(args) = self.args_for_mir_body() {
|
|
tcx.instantiate_and_normalize_erasing_regions(args, typing_env, v)
|
|
} else {
|
|
tcx.normalize_erasing_regions(typing_env, v.instantiate_identity())
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
// Keep me in sync with instantiate_mir_and_normalize_erasing_regions
|
|
pub fn try_instantiate_mir_and_normalize_erasing_regions<T>(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
v: EarlyBinder<'tcx, T>,
|
|
) -> Result<T, NormalizationError<'tcx>>
|
|
where
|
|
T: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
if let Some(args) = self.args_for_mir_body() {
|
|
tcx.try_instantiate_and_normalize_erasing_regions(args, typing_env, v)
|
|
} else {
|
|
// We're using `instantiate_identity` as e.g.
|
|
// `FnPtrShim` is separately generated for every
|
|
// instantiation of the `FnDef`, so the MIR body
|
|
// is already instantiated. Any generic parameters it
|
|
// contains are generic parameters from the caller.
|
|
tcx.try_normalize_erasing_regions(typing_env, v.instantiate_identity())
|
|
}
|
|
}
|
|
}
|
|
|
|
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))
|
|
}
|
|
}
|