1 use crate::middle
::codegen_fn_attrs
::CodegenFnAttrFlags
;
2 use crate::ty
::print
::{FmtPrinter, Printer}
;
3 use crate::ty
::subst
::{InternalSubsts, Subst}
;
5 self, EarlyBinder
, SubstsRef
, Ty
, TyCtxt
, TypeFoldable
, TypeSuperFoldable
, TypeVisitable
,
7 use rustc_errors
::ErrorGuaranteed
;
8 use rustc_hir
::def
::Namespace
;
9 use rustc_hir
::def_id
::{CrateNum, DefId}
;
10 use rustc_hir
::lang_items
::LangItem
;
11 use rustc_macros
::HashStable
;
12 use rustc_middle
::ty
::normalize_erasing_regions
::NormalizationError
;
13 use rustc_span
::Symbol
;
17 /// A monomorphized `InstanceDef`.
19 /// Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type
20 /// simply couples a potentially generic `InstanceDef` with some substs, and codegen and const eval
21 /// will do all required substitution as they run.
22 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
23 #[derive(HashStable, Lift, TypeFoldable, TypeVisitable)]
24 pub struct Instance
<'tcx
> {
25 pub def
: InstanceDef
<'tcx
>,
26 pub substs
: SubstsRef
<'tcx
>,
29 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
30 #[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable, Lift)]
31 pub enum InstanceDef
<'tcx
> {
32 /// A user-defined callable item.
38 Item(ty
::WithOptConstParam
<DefId
>),
40 /// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI).
42 /// Alongside `Virtual`, this is the only `InstanceDef` that does not have its own callable MIR.
43 /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the
47 /// `<T as Trait>::method` where `method` receives unsizeable `self: Self` (part of the
48 /// `unsized_locals` feature).
50 /// The generated shim will take `Self` via `*mut Self` - conceptually this is `&owned Self` -
51 /// and dereference the argument to call the original function.
54 /// `fn()` pointer where the function itself cannot be turned into a pointer.
56 /// One example is `<dyn Trait as Trait>::fn`, where the shim contains
57 /// a virtual call, which codegen supports only via a direct call to the
58 /// `<dyn Trait as Trait>::fn` instance (an `InstanceDef::Virtual`).
60 /// Another example is functions annotated with `#[track_caller]`, which
61 /// must have their implicit caller location argument populated for a call.
62 /// Because this is a required part of the function's ABI but can't be tracked
63 /// as a property of the function pointer, we use a single "caller location"
64 /// (the definition of the function itself).
67 /// `<fn() as FnTrait>::call_*` (generated `FnTrait` implementation for `fn()` pointers).
69 /// `DefId` is `FnTrait::call_*`.
70 FnPtrShim(DefId
, Ty
<'tcx
>),
72 /// Dynamic dispatch to `<dyn Trait as Trait>::fn`.
74 /// This `InstanceDef` does not have callable MIR. Calls to `Virtual` instances must be
75 /// codegen'd as virtual calls through the vtable.
77 /// If this is reified to a `fn` pointer, a `ReifyShim` is used (see `ReifyShim` above for more
79 Virtual(DefId
, usize),
81 /// `<[FnMut closure] as FnOnce>::call_once`.
83 /// The `DefId` is the ID of the `call_once` method in `FnOnce`.
84 ClosureOnceShim { call_once: DefId, track_caller: bool }
,
86 /// `core::ptr::drop_in_place::<T>`.
88 /// The `DefId` is for `core::ptr::drop_in_place`.
89 /// The `Option<Ty<'tcx>>` is either `Some(T)`, or `None` for empty drop
91 DropGlue(DefId
, Option
<Ty
<'tcx
>>),
93 /// Compiler-generated `<T as Clone>::clone` implementation.
95 /// For all types that automatically implement `Copy`, a trivial `Clone` impl is provided too.
96 /// Additionally, arrays, tuples, and closures get a `Clone` shim even if they aren't `Copy`.
98 /// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl.
99 CloneShim(DefId
, Ty
<'tcx
>),
102 impl<'tcx
> Instance
<'tcx
> {
103 /// Returns the `Ty` corresponding to this `Instance`, with generic substitutions applied and
104 /// lifetimes erased, allowing a `ParamEnv` to be specified for use during normalization.
105 pub fn ty(&self, tcx
: TyCtxt
<'tcx
>, param_env
: ty
::ParamEnv
<'tcx
>) -> Ty
<'tcx
> {
106 let ty
= tcx
.type_of(self.def
.def_id());
107 tcx
.subst_and_normalize_erasing_regions(self.substs
, param_env
, ty
)
110 /// Finds a crate that contains a monomorphization of this instance that
111 /// can be linked to from the local crate. A return value of `None` means
112 /// no upstream crate provides such an exported monomorphization.
114 /// This method already takes into account the global `-Zshare-generics`
115 /// setting, always returning `None` if `share-generics` is off.
116 pub fn upstream_monomorphization(&self, tcx
: TyCtxt
<'tcx
>) -> Option
<CrateNum
> {
117 // If we are not in share generics mode, we don't link to upstream
118 // monomorphizations but always instantiate our own internal versions
120 if !tcx
.sess
.opts
.share_generics() {
124 // If this is an item that is defined in the local crate, no upstream
125 // crate can know about it/provide a monomorphization.
126 if self.def_id().is_local() {
130 // If this a non-generic instance, it cannot be a shared monomorphization.
131 self.substs
.non_erasable_generics().next()?
;
134 InstanceDef
::Item(def
) => tcx
135 .upstream_monomorphizations_for(def
.did
)
136 .and_then(|monos
| monos
.get(&self.substs
).cloned()),
137 InstanceDef
::DropGlue(_
, Some(_
)) => tcx
.upstream_drop_glue_for(self.substs
),
143 impl<'tcx
> InstanceDef
<'tcx
> {
145 pub fn def_id(self) -> DefId
{
147 InstanceDef
::Item(def
) => def
.did
,
148 InstanceDef
::VTableShim(def_id
)
149 | InstanceDef
::ReifyShim(def_id
)
150 | InstanceDef
::FnPtrShim(def_id
, _
)
151 | InstanceDef
::Virtual(def_id
, _
)
152 | InstanceDef
::Intrinsic(def_id
)
153 | InstanceDef
::ClosureOnceShim { call_once: def_id, track_caller: _ }
154 | InstanceDef
::DropGlue(def_id
, _
)
155 | InstanceDef
::CloneShim(def_id
, _
) => def_id
,
159 /// Returns the `DefId` of instances which might not require codegen locally.
160 pub fn def_id_if_not_guaranteed_local_codegen(self) -> Option
<DefId
> {
162 ty
::InstanceDef
::Item(def
) => Some(def
.did
),
163 ty
::InstanceDef
::DropGlue(def_id
, Some(_
)) => Some(def_id
),
164 InstanceDef
::VTableShim(..)
165 | InstanceDef
::ReifyShim(..)
166 | InstanceDef
::FnPtrShim(..)
167 | InstanceDef
::Virtual(..)
168 | InstanceDef
::Intrinsic(..)
169 | InstanceDef
::ClosureOnceShim { .. }
170 | InstanceDef
::DropGlue(..)
171 | InstanceDef
::CloneShim(..) => None
,
176 pub fn with_opt_param(self) -> ty
::WithOptConstParam
<DefId
> {
178 InstanceDef
::Item(def
) => def
,
179 InstanceDef
::VTableShim(def_id
)
180 | InstanceDef
::ReifyShim(def_id
)
181 | InstanceDef
::FnPtrShim(def_id
, _
)
182 | InstanceDef
::Virtual(def_id
, _
)
183 | InstanceDef
::Intrinsic(def_id
)
184 | InstanceDef
::ClosureOnceShim { call_once: def_id, track_caller: _ }
185 | InstanceDef
::DropGlue(def_id
, _
)
186 | InstanceDef
::CloneShim(def_id
, _
) => ty
::WithOptConstParam
::unknown(def_id
),
191 pub fn get_attrs(&self, tcx
: TyCtxt
<'tcx
>, attr
: Symbol
) -> ty
::Attributes
<'tcx
> {
192 tcx
.get_attrs(self.def_id(), attr
)
195 /// Returns `true` if the LLVM version of this instance is unconditionally
196 /// marked with `inline`. This implies that a copy of this instance is
197 /// generated in every codegen unit.
198 /// Note that this is only a hint. See the documentation for
199 /// `generates_cgu_internal_copy` for more information.
200 pub fn requires_inline(&self, tcx
: TyCtxt
<'tcx
>) -> bool
{
201 use rustc_hir
::definitions
::DefPathData
;
202 let def_id
= match *self {
203 ty
::InstanceDef
::Item(def
) => def
.did
,
204 ty
::InstanceDef
::DropGlue(_
, Some(_
)) => return false,
208 tcx
.def_key(def_id
).disambiguated_data
.data
,
209 DefPathData
::Ctor
| DefPathData
::ClosureExpr
213 /// Returns `true` if the machine code for this instance is instantiated in
214 /// each codegen unit that references it.
215 /// Note that this is only a hint! The compiler can globally decide to *not*
216 /// do this in order to speed up compilation. CGU-internal copies are
217 /// only exist to enable inlining. If inlining is not performed (e.g. at
218 /// `-Copt-level=0`) then the time for generating them is wasted and it's
219 /// better to create a single copy with external linkage.
220 pub fn generates_cgu_internal_copy(&self, tcx
: TyCtxt
<'tcx
>) -> bool
{
221 if self.requires_inline(tcx
) {
224 if let ty
::InstanceDef
::DropGlue(.., Some(ty
)) = *self {
225 // Drop glue generally wants to be instantiated at every codegen
226 // unit, but without an #[inline] hint. We should make this
227 // available to normal end-users.
228 if tcx
.sess
.opts
.incremental
.is_none() {
231 // When compiling with incremental, we can generate a *lot* of
232 // codegen units. Including drop glue into all of them has a
233 // considerable compile time cost.
235 // We include enums without destructors to allow, say, optimizing
236 // drops of `Option::None` before LTO. We also respect the intent of
237 // `#[inline]` on `Drop::drop` implementations.
238 return ty
.ty_adt_def().map_or(true, |adt_def
| {
239 adt_def
.destructor(tcx
).map_or_else(
240 || adt_def
.is_enum(),
241 |dtor
| tcx
.codegen_fn_attrs(dtor
.did
).requests_inline(),
245 tcx
.codegen_fn_attrs(self.def_id()).requests_inline()
248 pub fn requires_caller_location(&self, tcx
: TyCtxt
<'_
>) -> bool
{
250 InstanceDef
::Item(ty
::WithOptConstParam { did: def_id, .. }
)
251 | InstanceDef
::Virtual(def_id
, _
) => {
252 tcx
.body_codegen_attrs(def_id
).flags
.contains(CodegenFnAttrFlags
::TRACK_CALLER
)
254 InstanceDef
::ClosureOnceShim { call_once: _, track_caller }
=> track_caller
,
259 /// Returns `true` when the MIR body associated with this instance should be monomorphized
260 /// by its users (e.g. codegen or miri) by substituting the `substs` from `Instance` (see
261 /// `Instance::substs_for_mir_body`).
263 /// Otherwise, returns `false` only for some kinds of shims where the construction of the MIR
264 /// body should perform necessary substitutions.
265 pub fn has_polymorphic_mir_body(&self) -> bool
{
267 InstanceDef
::CloneShim(..)
268 | InstanceDef
::FnPtrShim(..)
269 | InstanceDef
::DropGlue(_
, Some(_
)) => false,
270 InstanceDef
::ClosureOnceShim { .. }
271 | InstanceDef
::DropGlue(..)
272 | InstanceDef
::Item(_
)
273 | InstanceDef
::Intrinsic(..)
274 | InstanceDef
::ReifyShim(..)
275 | InstanceDef
::Virtual(..)
276 | InstanceDef
::VTableShim(..) => true,
281 impl<'tcx
> fmt
::Display
for Instance
<'tcx
> {
282 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
283 ty
::tls
::with(|tcx
| {
284 let substs
= tcx
.lift(self.substs
).expect("could not lift for printing");
285 let s
= FmtPrinter
::new(tcx
, Namespace
::ValueNS
)
286 .print_def_path(self.def_id(), substs
)?
292 InstanceDef
::Item(_
) => Ok(()),
293 InstanceDef
::VTableShim(_
) => write
!(f
, " - shim(vtable)"),
294 InstanceDef
::ReifyShim(_
) => write
!(f
, " - shim(reify)"),
295 InstanceDef
::Intrinsic(_
) => write
!(f
, " - intrinsic"),
296 InstanceDef
::Virtual(_
, num
) => write
!(f
, " - virtual#{}", num
),
297 InstanceDef
::FnPtrShim(_
, ty
) => write
!(f
, " - shim({})", ty
),
298 InstanceDef
::ClosureOnceShim { .. }
=> write
!(f
, " - shim"),
299 InstanceDef
::DropGlue(_
, None
) => write
!(f
, " - shim(None)"),
300 InstanceDef
::DropGlue(_
, Some(ty
)) => write
!(f
, " - shim(Some({}))", ty
),
301 InstanceDef
::CloneShim(_
, ty
) => write
!(f
, " - shim({})", ty
),
306 impl<'tcx
> Instance
<'tcx
> {
307 pub fn new(def_id
: DefId
, substs
: SubstsRef
<'tcx
>) -> Instance
<'tcx
> {
309 !substs
.has_escaping_bound_vars(),
310 "substs of instance {:?} not normalized for codegen: {:?}",
314 Instance { def: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs }
317 pub fn mono(tcx
: TyCtxt
<'tcx
>, def_id
: DefId
) -> Instance
<'tcx
> {
318 let substs
= InternalSubsts
::for_item(tcx
, def_id
, |param
, _
| match param
.kind
{
319 ty
::GenericParamDefKind
::Lifetime
=> tcx
.lifetimes
.re_erased
.into(),
320 ty
::GenericParamDefKind
::Type { .. }
=> {
321 bug
!("Instance::mono: {:?} has type parameters", def_id
)
323 ty
::GenericParamDefKind
::Const { .. }
=> {
324 bug
!("Instance::mono: {:?} has const parameters", def_id
)
328 Instance
::new(def_id
, substs
)
332 pub fn def_id(&self) -> DefId
{
336 /// Resolves a `(def_id, substs)` pair to an (optional) instance -- most commonly,
337 /// this is used to find the precise code that will run for a trait method invocation,
340 /// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance.
341 /// For example, in a context like this,
343 /// ```ignore (illustrative)
344 /// fn foo<T: Debug>(t: T) { ... }
347 /// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not
348 /// know what code ought to run. (Note that this setting is also affected by the
349 /// `RevealMode` in the parameter environment.)
351 /// Presuming that coherence and type-check have succeeded, if this method is invoked
352 /// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return
353 /// `Ok(Some(instance))`.
355 /// Returns `Err(ErrorGuaranteed)` when the `Instance` resolution process
356 /// couldn't complete due to errors elsewhere - this is distinct
357 /// from `Ok(None)` to avoid misleading diagnostics when an error
358 /// has already been/will be emitted, for the original cause
361 param_env
: ty
::ParamEnv
<'tcx
>,
363 substs
: SubstsRef
<'tcx
>,
364 ) -> Result
<Option
<Instance
<'tcx
>>, ErrorGuaranteed
> {
365 Instance
::resolve_opt_const_arg(
368 ty
::WithOptConstParam
::unknown(def_id
),
373 // This should be kept up to date with `resolve`.
374 pub fn resolve_opt_const_arg(
376 param_env
: ty
::ParamEnv
<'tcx
>,
377 def
: ty
::WithOptConstParam
<DefId
>,
378 substs
: SubstsRef
<'tcx
>,
379 ) -> Result
<Option
<Instance
<'tcx
>>, ErrorGuaranteed
> {
380 // All regions in the result of this query are erased, so it's
381 // fine to erase all of the input regions.
383 // HACK(eddyb) erase regions in `substs` first, so that `param_env.and(...)`
384 // below is more likely to ignore the bounds in scope (e.g. if the only
385 // generic parameters mentioned by `substs` were lifetime ones).
386 let substs
= tcx
.erase_regions(substs
);
388 // FIXME(eddyb) should this always use `param_env.with_reveal_all()`?
389 if let Some((did
, param_did
)) = def
.as_const_arg() {
390 tcx
.resolve_instance_of_const_arg(
391 tcx
.erase_regions(param_env
.and((did
, param_did
, substs
))),
394 tcx
.resolve_instance(tcx
.erase_regions(param_env
.and((def
.did
, substs
))))
398 pub fn resolve_for_fn_ptr(
400 param_env
: ty
::ParamEnv
<'tcx
>,
402 substs
: SubstsRef
<'tcx
>,
403 ) -> Option
<Instance
<'tcx
>> {
404 debug
!("resolve(def_id={:?}, substs={:?})", def_id
, substs
);
405 // Use either `resolve_closure` or `resolve_for_vtable`
406 assert
!(!tcx
.is_closure(def_id
), "Called `resolve_for_fn_ptr` on closure: {:?}", def_id
);
407 Instance
::resolve(tcx
, param_env
, def_id
, substs
).ok().flatten().map(|mut resolved
| {
409 InstanceDef
::Item(def
) if resolved
.def
.requires_caller_location(tcx
) => {
410 debug
!(" => fn pointer created for function with #[track_caller]");
411 resolved
.def
= InstanceDef
::ReifyShim(def
.did
);
413 InstanceDef
::Virtual(def_id
, _
) => {
414 debug
!(" => fn pointer created for virtual call");
415 resolved
.def
= InstanceDef
::ReifyShim(def_id
);
424 pub fn resolve_for_vtable(
426 param_env
: ty
::ParamEnv
<'tcx
>,
428 substs
: SubstsRef
<'tcx
>,
429 ) -> Option
<Instance
<'tcx
>> {
430 debug
!("resolve_for_vtable(def_id={:?}, substs={:?})", def_id
, substs
);
431 let fn_sig
= tcx
.fn_sig(def_id
);
432 let is_vtable_shim
= !fn_sig
.inputs().skip_binder().is_empty()
433 && fn_sig
.input(0).skip_binder().is_param(0)
434 && tcx
.generics_of(def_id
).has_self
;
436 debug
!(" => associated item with unsizeable self: Self");
437 Some(Instance { def: InstanceDef::VTableShim(def_id), substs }
)
439 Instance
::resolve(tcx
, param_env
, def_id
, substs
).ok().flatten().map(|mut resolved
| {
441 InstanceDef
::Item(def
) => {
442 // We need to generate a shim when we cannot guarantee that
443 // the caller of a trait object method will be aware of
444 // `#[track_caller]` - this ensures that the caller
445 // and callee ABI will always match.
447 // The shim is generated when all of these conditions are met:
449 // 1) The underlying method expects a caller location parameter
451 if resolved
.def
.requires_caller_location(tcx
)
452 // 2) The caller location parameter comes from having `#[track_caller]`
453 // on the implementation, and *not* on the trait method.
454 && !tcx
.should_inherit_track_caller(def
.did
)
455 // If the method implementation comes from the trait definition itself
456 // (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`),
457 // then we don't need to generate a shim. This check is needed because
458 // `should_inherit_track_caller` returns `false` if our method
459 // implementation comes from the trait block, and not an impl block
461 tcx
.opt_associated_item(def
.did
),
463 container
: ty
::AssocItemContainer
::TraitContainer
,
468 if tcx
.is_closure(def
.did
) {
469 debug
!(" => vtable fn pointer created for closure with #[track_caller]: {:?} for method {:?} {:?}",
470 def
.did
, def_id
, substs
);
472 // Create a shim for the `FnOnce/FnMut/Fn` method we are calling
473 // - unlike functions, invoking a closure always goes through a
475 resolved
= Instance { def: InstanceDef::ReifyShim(def_id), substs }
;
478 " => vtable fn pointer created for function with #[track_caller]: {:?}", def
.did
480 resolved
.def
= InstanceDef
::ReifyShim(def
.did
);
484 InstanceDef
::Virtual(def_id
, _
) => {
485 debug
!(" => vtable fn pointer created for virtual call");
486 resolved
.def
= InstanceDef
::ReifyShim(def_id
);
496 pub fn resolve_closure(
499 substs
: ty
::SubstsRef
<'tcx
>,
500 requested_kind
: ty
::ClosureKind
,
501 ) -> Option
<Instance
<'tcx
>> {
502 let actual_kind
= substs
.as_closure().kind();
504 match needs_fn_once_adapter_shim(actual_kind
, requested_kind
) {
505 Ok(true) => Instance
::fn_once_adapter_instance(tcx
, def_id
, substs
),
506 _
=> Some(Instance
::new(def_id
, substs
)),
510 pub fn resolve_drop_in_place(tcx
: TyCtxt
<'tcx
>, ty
: Ty
<'tcx
>) -> ty
::Instance
<'tcx
> {
511 let def_id
= tcx
.require_lang_item(LangItem
::DropInPlace
, None
);
512 let substs
= tcx
.intern_substs(&[ty
.into()]);
513 Instance
::resolve(tcx
, ty
::ParamEnv
::reveal_all(), def_id
, substs
).unwrap().unwrap()
516 pub fn fn_once_adapter_instance(
519 substs
: ty
::SubstsRef
<'tcx
>,
520 ) -> Option
<Instance
<'tcx
>> {
521 debug
!("fn_once_adapter_shim({:?}, {:?})", closure_did
, substs
);
522 let fn_once
= tcx
.require_lang_item(LangItem
::FnOnce
, None
);
524 .associated_items(fn_once
)
525 .in_definition_order()
526 .find(|it
| it
.kind
== ty
::AssocKind
::Fn
)
530 tcx
.codegen_fn_attrs(closure_did
).flags
.contains(CodegenFnAttrFlags
::TRACK_CALLER
);
531 let def
= ty
::InstanceDef
::ClosureOnceShim { call_once, track_caller }
;
533 let self_ty
= tcx
.mk_closure(closure_did
, substs
);
535 let sig
= substs
.as_closure().sig();
537 tcx
.try_normalize_erasing_late_bound_regions(ty
::ParamEnv
::reveal_all(), sig
).ok()?
;
538 assert_eq
!(sig
.inputs().len(), 1);
539 let substs
= tcx
.mk_substs_trait(self_ty
, &[sig
.inputs()[0].into()]);
541 debug
!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty
, sig
);
542 Some(Instance { def, substs }
)
545 /// Depending on the kind of `InstanceDef`, the MIR body associated with an
546 /// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other
547 /// cases the MIR body is expressed in terms of the types found in the substitution array.
548 /// In the former case, we want to substitute those generic types and replace them with the
549 /// values from the substs when monomorphizing the function body. But in the latter case, we
550 /// don't want to do that substitution, since it has already been done effectively.
552 /// This function returns `Some(substs)` in the former case and `None` otherwise -- i.e., if
553 /// this function returns `None`, then the MIR body does not require substitution during
555 fn substs_for_mir_body(&self) -> Option
<SubstsRef
<'tcx
>> {
556 if self.def
.has_polymorphic_mir_body() { Some(self.substs) }
else { None }
559 pub fn subst_mir
<T
>(&self, tcx
: TyCtxt
<'tcx
>, v
: &T
) -> T
561 T
: TypeFoldable
<'tcx
> + Copy
,
563 if let Some(substs
) = self.substs_for_mir_body() {
564 EarlyBinder(*v
).subst(tcx
, substs
)
571 pub fn subst_mir_and_normalize_erasing_regions
<T
>(
574 param_env
: ty
::ParamEnv
<'tcx
>,
578 T
: TypeFoldable
<'tcx
> + Clone
,
580 if let Some(substs
) = self.substs_for_mir_body() {
581 tcx
.subst_and_normalize_erasing_regions(substs
, param_env
, v
)
583 tcx
.normalize_erasing_regions(param_env
, v
)
588 pub fn try_subst_mir_and_normalize_erasing_regions
<T
>(
591 param_env
: ty
::ParamEnv
<'tcx
>,
593 ) -> Result
<T
, NormalizationError
<'tcx
>>
595 T
: TypeFoldable
<'tcx
> + Clone
,
597 if let Some(substs
) = self.substs_for_mir_body() {
598 tcx
.try_subst_and_normalize_erasing_regions(substs
, param_env
, v
)
600 tcx
.try_normalize_erasing_regions(param_env
, v
)
604 /// Returns a new `Instance` where generic parameters in `instance.substs` are replaced by
605 /// identity parameters if they are determined to be unused in `instance.def`.
606 pub fn polymorphize(self, tcx
: TyCtxt
<'tcx
>) -> Self {
607 debug
!("polymorphize: running polymorphization analysis");
608 if !tcx
.sess
.opts
.unstable_opts
.polymorphize
{
612 let polymorphized_substs
= polymorphize(tcx
, self.def
, self.substs
);
613 debug
!("polymorphize: self={:?} polymorphized_substs={:?}", self, polymorphized_substs
);
614 Self { def: self.def, substs: polymorphized_substs }
618 fn polymorphize
<'tcx
>(
620 instance
: ty
::InstanceDef
<'tcx
>,
621 substs
: SubstsRef
<'tcx
>,
622 ) -> SubstsRef
<'tcx
> {
623 debug
!("polymorphize({:?}, {:?})", instance
, substs
);
624 let unused
= tcx
.unused_generic_params(instance
);
625 debug
!("polymorphize: unused={:?}", unused
);
627 // If this is a closure or generator then we need to handle the case where another closure
628 // from the function is captured as an upvar and hasn't been polymorphized. In this case,
629 // the unpolymorphized upvar closure would result in a polymorphized closure producing
630 // multiple mono items (and eventually symbol clashes).
631 let def_id
= instance
.def_id();
632 let upvars_ty
= if tcx
.is_closure(def_id
) {
633 Some(substs
.as_closure().tupled_upvars_ty())
634 } else if tcx
.type_of(def_id
).is_generator() {
635 Some(substs
.as_generator().tupled_upvars_ty())
639 let has_upvars
= upvars_ty
.map_or(false, |ty
| !ty
.tuple_fields().is_empty());
640 debug
!("polymorphize: upvars_ty={:?} has_upvars={:?}", upvars_ty
, has_upvars
);
642 struct PolymorphizationFolder
<'tcx
> {
646 impl<'tcx
> ty
::TypeFolder
<'tcx
> for PolymorphizationFolder
<'tcx
> {
647 fn tcx
<'a
>(&'a
self) -> TyCtxt
<'tcx
> {
651 fn fold_ty(&mut self, ty
: Ty
<'tcx
>) -> Ty
<'tcx
> {
652 debug
!("fold_ty: ty={:?}", ty
);
654 ty
::Closure(def_id
, substs
) => {
655 let polymorphized_substs
= polymorphize(
657 ty
::InstanceDef
::Item(ty
::WithOptConstParam
::unknown(def_id
)),
660 if substs
== polymorphized_substs
{
663 self.tcx
.mk_closure(def_id
, polymorphized_substs
)
666 ty
::Generator(def_id
, substs
, movability
) => {
667 let polymorphized_substs
= polymorphize(
669 ty
::InstanceDef
::Item(ty
::WithOptConstParam
::unknown(def_id
)),
672 if substs
== polymorphized_substs
{
675 self.tcx
.mk_generator(def_id
, polymorphized_substs
, movability
)
678 _
=> ty
.super_fold_with(self),
683 InternalSubsts
::for_item(tcx
, def_id
, |param
, _
| {
684 let is_unused
= unused
.contains(param
.index
).unwrap_or(false);
685 debug
!("polymorphize: param={:?} is_unused={:?}", param
, is_unused
);
687 // Upvar case: If parameter is a type parameter..
688 ty
::GenericParamDefKind
::Type { .. }
if
689 // ..and has upvars..
691 // ..and this param has the same type as the tupled upvars..
692 upvars_ty
== Some(substs
[param
.index
as usize].expect_ty()) => {
693 // ..then double-check that polymorphization marked it used..
694 debug_assert
!(!is_unused
);
695 // ..and polymorphize any closures/generators captured as upvars.
696 let upvars_ty
= upvars_ty
.unwrap();
697 let polymorphized_upvars_ty
= upvars_ty
.fold_with(
698 &mut PolymorphizationFolder { tcx }
);
699 debug
!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty
);
700 ty
::GenericArg
::from(polymorphized_upvars_ty
)
703 // Simple case: If parameter is a const or type parameter..
704 ty
::GenericParamDefKind
::Const { .. }
| ty
::GenericParamDefKind
::Type { .. }
if
705 // ..and is within range and unused..
706 unused
.contains(param
.index
).unwrap_or(false) =>
707 // ..then use the identity for this parameter.
708 tcx
.mk_param_from_def(param
),
710 // Otherwise, use the parameter as before.
711 _
=> substs
[param
.index
as usize],
716 fn needs_fn_once_adapter_shim(
717 actual_closure_kind
: ty
::ClosureKind
,
718 trait_closure_kind
: ty
::ClosureKind
,
719 ) -> Result
<bool
, ()> {
720 match (actual_closure_kind
, trait_closure_kind
) {
721 (ty
::ClosureKind
::Fn
, ty
::ClosureKind
::Fn
)
722 | (ty
::ClosureKind
::FnMut
, ty
::ClosureKind
::FnMut
)
723 | (ty
::ClosureKind
::FnOnce
, ty
::ClosureKind
::FnOnce
) => {
724 // No adapter needed.
727 (ty
::ClosureKind
::Fn
, ty
::ClosureKind
::FnMut
) => {
728 // The closure fn `llfn` is a `fn(&self, ...)`. We want a
729 // `fn(&mut self, ...)`. In fact, at codegen time, these are
730 // basically the same thing, so we can just return llfn.
733 (ty
::ClosureKind
::Fn
| ty
::ClosureKind
::FnMut
, ty
::ClosureKind
::FnOnce
) => {
734 // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
735 // self, ...)`. We want a `fn(self, ...)`. We can produce
736 // this by doing something like:
738 // fn call_once(self, ...) { call_mut(&self, ...) }
739 // fn call_once(mut self, ...) { call_mut(&mut self, ...) }
741 // These are both the same at codegen time.
744 (ty
::ClosureKind
::FnMut
| ty
::ClosureKind
::FnOnce
, _
) => Err(()),