1 //! Mono Item Collection
2 //! ====================
4 //! This module is responsible for discovering all items that will contribute
5 //! to code generation of the crate. The important part here is that it not only
6 //! needs to find syntax-level items (functions, structs, etc) but also all
7 //! their monomorphized instantiations. Every non-generic, non-const function
8 //! maps to one LLVM artifact. Every generic function can produce
9 //! from zero to N artifacts, depending on the sets of type arguments it
10 //! is instantiated with.
11 //! This also applies to generic items from other crates: A generic definition
12 //! in crate X might produce monomorphizations that are compiled into crate Y.
13 //! We also have to collect these here.
15 //! The following kinds of "mono items" are handled here:
23 //! The following things also result in LLVM artifacts, but are not collected
24 //! here, since we instantiate them locally on demand when needed in a given
34 //! Let's define some terms first:
36 //! - A "mono item" is something that results in a function or global in
37 //! the LLVM IR of a codegen unit. Mono items do not stand on their
38 //! own, they can reference other mono items. For example, if function
39 //! `foo()` calls function `bar()` then the mono item for `foo()`
40 //! references the mono item for function `bar()`. In general, the
41 //! definition for mono item A referencing a mono item B is that
42 //! the LLVM artifact produced for A references the LLVM artifact produced
45 //! - Mono items and the references between them form a directed graph,
46 //! where the mono items are the nodes and references form the edges.
47 //! Let's call this graph the "mono item graph".
49 //! - The mono item graph for a program contains all mono items
50 //! that are needed in order to produce the complete LLVM IR of the program.
52 //! The purpose of the algorithm implemented in this module is to build the
53 //! mono item graph for the current crate. It runs in two phases:
55 //! 1. Discover the roots of the graph by traversing the HIR of the crate.
56 //! 2. Starting from the roots, find neighboring nodes by inspecting the MIR
57 //! representation of the item corresponding to a given node, until no more
58 //! new nodes are found.
60 //! ### Discovering roots
62 //! The roots of the mono item graph correspond to the public non-generic
63 //! syntactic items in the source code. We find them by walking the HIR of the
64 //! crate, and whenever we hit upon a public function, method, or static item,
65 //! we create a mono item consisting of the items DefId and, since we only
66 //! consider non-generic items, an empty type-substitution set. (In eager
67 //! collection mode, during incremental compilation, all non-generic functions
68 //! are considered as roots, as well as when the `-Clink-dead-code` option is
69 //! specified. Functions marked `#[no_mangle]` and functions called by inlinable
70 //! functions also always act as roots.)
72 //! ### Finding neighbor nodes
73 //! Given a mono item node, we can discover neighbors by inspecting its
74 //! MIR. We walk the MIR and any time we hit upon something that signifies a
75 //! reference to another mono item, we have found a neighbor. Since the
76 //! mono item we are currently at is always monomorphic, we also know the
77 //! concrete type arguments of its neighbors, and so all neighbors again will be
78 //! monomorphic. The specific forms a reference to a neighboring node can take
79 //! in MIR are quite diverse. Here is an overview:
81 //! #### Calling Functions/Methods
82 //! The most obvious form of one mono item referencing another is a
83 //! function or method call (represented by a CALL terminator in MIR). But
84 //! calls are not the only thing that might introduce a reference between two
85 //! function mono items, and as we will see below, they are just a
86 //! specialization of the form described next, and consequently will not get any
87 //! special treatment in the algorithm.
89 //! #### Taking a reference to a function or method
90 //! A function does not need to actually be called in order to be a neighbor of
91 //! another function. It suffices to just take a reference in order to introduce
92 //! an edge. Consider the following example:
95 //! fn print_val<T: Display>(x: T) {
96 //! println!("{}", x);
99 //! fn call_fn(f: &Fn(i32), x: i32) {
104 //! let print_i32 = print_val::<i32>;
105 //! call_fn(&print_i32, 0);
108 //! The MIR of none of these functions will contain an explicit call to
109 //! `print_val::<i32>`. Nonetheless, in order to mono this program, we need
110 //! an instance of this function. Thus, whenever we encounter a function or
111 //! method in operand position, we treat it as a neighbor of the current
112 //! mono item. Calls are just a special case of that.
115 //! In a way, closures are a simple case. Since every closure object needs to be
116 //! constructed somewhere, we can reliably discover them by observing
117 //! `RValue::Aggregate` expressions with `AggregateKind::Closure`. This is also
118 //! true for closures inlined from other crates.
121 //! Drop glue mono items are introduced by MIR drop-statements. The
122 //! generated mono item will again have drop-glue item neighbors if the
123 //! type to be dropped contains nested values that also need to be dropped. It
124 //! might also have a function item neighbor for the explicit `Drop::drop`
125 //! implementation of its type.
127 //! #### Unsizing Casts
128 //! A subtle way of introducing neighbor edges is by casting to a trait object.
129 //! Since the resulting fat-pointer contains a reference to a vtable, we need to
130 //! instantiate all object-save methods of the trait, as we need to store
131 //! pointers to these functions even if they never get called anywhere. This can
132 //! be seen as a special case of taking a function reference.
135 //! Since `Box` expression have special compiler support, no explicit calls to
136 //! `exchange_malloc()` and `box_free()` may show up in MIR, even if the
137 //! compiler will generate them. We have to observe `Rvalue::Box` expressions
138 //! and Box-typed drop-statements for that purpose.
141 //! Interaction with Cross-Crate Inlining
142 //! -------------------------------------
143 //! The binary of a crate will not only contain machine code for the items
144 //! defined in the source code of that crate. It will also contain monomorphic
145 //! instantiations of any extern generic functions and of functions marked with
147 //! The collection algorithm handles this more or less mono. If it is
148 //! about to create a mono item for something with an external `DefId`,
149 //! it will take a look if the MIR for that item is available, and if so just
150 //! proceed normally. If the MIR is not available, it assumes that the item is
151 //! just linked to and no node is created; which is exactly what we want, since
152 //! no machine code should be generated in the current crate for such an item.
154 //! Eager and Lazy Collection Mode
155 //! ------------------------------
156 //! Mono item collection can be performed in one of two modes:
158 //! - Lazy mode means that items will only be instantiated when actually
159 //! referenced. The goal is to produce the least amount of machine code
162 //! - Eager mode is meant to be used in conjunction with incremental compilation
163 //! where a stable set of mono items is more important than a minimal
164 //! one. Thus, eager mode will instantiate drop-glue for every drop-able type
165 //! in the crate, even if no drop call for that type exists (yet). It will
166 //! also instantiate default implementations of trait methods, something that
167 //! otherwise is only done on demand.
172 //! Some things are not yet fully implemented in the current version of this
176 //! Ideally, no mono item should be generated for const fns unless there
177 //! is a call to them that cannot be evaluated at compile time. At the moment
178 //! this is not implemented however: a mono item will be produced
179 //! regardless of whether it is actually needed or not.
181 use rustc_data_structures
::fx
::{FxHashMap, FxHashSet}
;
182 use rustc_data_structures
::sync
::{par_iter, MTLock, MTRef, ParallelIterator}
;
183 use rustc_errors
::{ErrorReported, FatalError}
;
184 use rustc_hir
as hir
;
185 use rustc_hir
::def_id
::{DefId, DefIdMap, LocalDefId, LOCAL_CRATE}
;
186 use rustc_hir
::itemlikevisit
::ItemLikeVisitor
;
187 use rustc_hir
::lang_items
::LangItem
;
188 use rustc_index
::bit_set
::GrowableBitSet
;
189 use rustc_middle
::mir
::interpret
::{AllocId, ConstValue}
;
190 use rustc_middle
::mir
::interpret
::{ErrorHandled, GlobalAlloc, Scalar}
;
191 use rustc_middle
::mir
::mono
::{InstantiationMode, MonoItem}
;
192 use rustc_middle
::mir
::visit
::Visitor
as MirVisitor
;
193 use rustc_middle
::mir
::{self, Local, Location}
;
194 use rustc_middle
::ty
::adjustment
::{CustomCoerceUnsized, PointerCast}
;
195 use rustc_middle
::ty
::print
::with_no_trimmed_paths
;
196 use rustc_middle
::ty
::subst
::{GenericArgKind, InternalSubsts}
;
197 use rustc_middle
::ty
::{self, GenericParamDefKind, Instance, Ty, TyCtxt, TypeFoldable, VtblEntry}
;
198 use rustc_middle
::{middle::codegen_fn_attrs::CodegenFnAttrFlags, mir::visit::TyContext}
;
199 use rustc_session
::config
::EntryFnType
;
200 use rustc_session
::lint
::builtin
::LARGE_ASSIGNMENTS
;
201 use rustc_session
::Limit
;
202 use rustc_span
::source_map
::{dummy_spanned, respan, Span, Spanned, DUMMY_SP}
;
203 use rustc_target
::abi
::Size
;
204 use smallvec
::SmallVec
;
207 use std
::path
::PathBuf
;
210 pub enum MonoItemCollectionMode
{
215 /// Maps every mono item to all mono items it references in its
217 pub struct InliningMap
<'tcx
> {
218 // Maps a source mono item to the range of mono items
220 // The range selects elements within the `targets` vecs.
221 index
: FxHashMap
<MonoItem
<'tcx
>, Range
<usize>>,
222 targets
: Vec
<MonoItem
<'tcx
>>,
224 // Contains one bit per mono item in the `targets` field. That bit
225 // is true if that mono item needs to be inlined into every CGU.
226 inlines
: GrowableBitSet
<usize>,
229 impl<'tcx
> InliningMap
<'tcx
> {
230 fn new() -> InliningMap
<'tcx
> {
232 index
: FxHashMap
::default(),
234 inlines
: GrowableBitSet
::with_capacity(1024),
238 fn record_accesses(&mut self, source
: MonoItem
<'tcx
>, new_targets
: &[(MonoItem
<'tcx
>, bool
)]) {
239 let start_index
= self.targets
.len();
240 let new_items_count
= new_targets
.len();
241 let new_items_count_total
= new_items_count
+ self.targets
.len();
243 self.targets
.reserve(new_items_count
);
244 self.inlines
.ensure(new_items_count_total
);
246 for (i
, (target
, inline
)) in new_targets
.iter().enumerate() {
247 self.targets
.push(*target
);
249 self.inlines
.insert(i
+ start_index
);
253 let end_index
= self.targets
.len();
254 assert
!(self.index
.insert(source
, start_index
..end_index
).is_none());
257 // Internally iterate over all items referenced by `source` which will be
258 // made available for inlining.
259 pub fn with_inlining_candidates
<F
>(&self, source
: MonoItem
<'tcx
>, mut f
: F
)
261 F
: FnMut(MonoItem
<'tcx
>),
263 if let Some(range
) = self.index
.get(&source
) {
264 for (i
, candidate
) in self.targets
[range
.clone()].iter().enumerate() {
265 if self.inlines
.contains(range
.start
+ i
) {
272 // Internally iterate over all items and the things each accesses.
273 pub fn iter_accesses
<F
>(&self, mut f
: F
)
275 F
: FnMut(MonoItem
<'tcx
>, &[MonoItem
<'tcx
>]),
277 for (&accessor
, range
) in &self.index
{
278 f(accessor
, &self.targets
[range
.clone()])
283 pub fn collect_crate_mono_items(
285 mode
: MonoItemCollectionMode
,
286 ) -> (FxHashSet
<MonoItem
<'_
>>, InliningMap
<'_
>) {
287 let _prof_timer
= tcx
.prof
.generic_activity("monomorphization_collector");
290 tcx
.sess
.time("monomorphization_collector_root_collections", || collect_roots(tcx
, mode
));
292 debug
!("building mono item graph, beginning at roots");
294 let mut visited
= MTLock
::new(FxHashSet
::default());
295 let mut inlining_map
= MTLock
::new(InliningMap
::new());
296 let recursion_limit
= tcx
.recursion_limit();
299 let visited
: MTRef
<'_
, _
> = &mut visited
;
300 let inlining_map
: MTRef
<'_
, _
> = &mut inlining_map
;
302 tcx
.sess
.time("monomorphization_collector_graph_walk", || {
303 par_iter(roots
).for_each(|root
| {
304 let mut recursion_depths
= DefIdMap
::default();
309 &mut recursion_depths
,
317 (visited
.into_inner(), inlining_map
.into_inner())
320 // Find all non-generic items by walking the HIR. These items serve as roots to
321 // start monomorphizing from.
322 fn collect_roots(tcx
: TyCtxt
<'_
>, mode
: MonoItemCollectionMode
) -> Vec
<MonoItem
<'_
>> {
323 debug
!("collecting roots");
324 let mut roots
= Vec
::new();
327 let entry_fn
= tcx
.entry_fn(());
329 debug
!("collect_roots: entry_fn = {:?}", entry_fn
);
331 let mut visitor
= RootCollector { tcx, mode, entry_fn, output: &mut roots }
;
333 tcx
.hir().visit_all_item_likes(&mut visitor
);
335 visitor
.push_extra_entry_roots();
338 // We can only codegen items that are instantiable - items all of
339 // whose predicates hold. Luckily, items that aren't instantiable
340 // can't actually be used, so we can just skip codegenning them.
343 .filter_map(|root
| root
.node
.is_instantiable(tcx
).then_some(root
.node
))
347 /// Collect all monomorphized items reachable from `starting_point`, and emit a note diagnostic if a
348 /// post-monorphization error is encountered during a collection step.
349 fn collect_items_rec
<'tcx
>(
351 starting_point
: Spanned
<MonoItem
<'tcx
>>,
352 visited
: MTRef
<'_
, MTLock
<FxHashSet
<MonoItem
<'tcx
>>>>,
353 recursion_depths
: &mut DefIdMap
<usize>,
354 recursion_limit
: Limit
,
355 inlining_map
: MTRef
<'_
, MTLock
<InliningMap
<'tcx
>>>,
357 if !visited
.lock_mut().insert(starting_point
.node
) {
358 // We've been here already, no need to search again.
361 debug
!("BEGIN collect_items_rec({})", starting_point
.node
);
363 let mut neighbors
= Vec
::new();
364 let recursion_depth_reset
;
367 // Post-monomorphization errors MVP
369 // We can encounter errors while monomorphizing an item, but we don't have a good way of
370 // showing a complete stack of spans ultimately leading to collecting the erroneous one yet.
371 // (It's also currently unclear exactly which diagnostics and information would be interesting
372 // to report in such cases)
374 // This leads to suboptimal error reporting: a post-monomorphization error (PME) will be
375 // shown with just a spanned piece of code causing the error, without information on where
376 // it was called from. This is especially obscure if the erroneous mono item is in a
377 // dependency. See for example issue #85155, where, before minimization, a PME happened two
378 // crates downstream from libcore's stdarch, without a way to know which dependency was the
381 // If such an error occurs in the current crate, its span will be enough to locate the
382 // source. If the cause is in another crate, the goal here is to quickly locate which mono
383 // item in the current crate is ultimately responsible for causing the error.
385 // To give at least _some_ context to the user: while collecting mono items, we check the
386 // error count. If it has changed, a PME occurred, and we trigger some diagnostics about the
387 // current step of mono items collection.
389 let error_count
= tcx
.sess
.diagnostic().err_count();
391 match starting_point
.node
{
392 MonoItem
::Static(def_id
) => {
393 let instance
= Instance
::mono(tcx
, def_id
);
395 // Sanity check whether this ended up being collected accidentally
396 debug_assert
!(should_codegen_locally(tcx
, &instance
));
398 let ty
= instance
.ty(tcx
, ty
::ParamEnv
::reveal_all());
399 visit_drop_use(tcx
, ty
, true, starting_point
.span
, &mut neighbors
);
401 recursion_depth_reset
= None
;
403 if let Ok(alloc
) = tcx
.eval_static_initializer(def_id
) {
404 for &id
in alloc
.relocations().values() {
405 collect_miri(tcx
, id
, &mut neighbors
);
409 MonoItem
::Fn(instance
) => {
410 // Sanity check whether this ended up being collected accidentally
411 debug_assert
!(should_codegen_locally(tcx
, &instance
));
413 // Keep track of the monomorphization recursion depth
414 recursion_depth_reset
= Some(check_recursion_limit(
421 check_type_length_limit(tcx
, instance
);
423 rustc_data_structures
::stack
::ensure_sufficient_stack(|| {
424 collect_neighbours(tcx
, instance
, &mut neighbors
);
427 MonoItem
::GlobalAsm(item_id
) => {
428 recursion_depth_reset
= None
;
430 let item
= tcx
.hir().item(item_id
);
431 if let hir
::ItemKind
::GlobalAsm(asm
) = item
.kind
{
432 for (op
, op_sp
) in asm
.operands
{
434 hir
::InlineAsmOperand
::Const { .. }
=> {
435 // Only constants which resolve to a plain integer
436 // are supported. Therefore the value should not
437 // depend on any other items.
439 _
=> span_bug
!(*op_sp
, "invalid operand type for global_asm!"),
443 span_bug
!(item
.span
, "Mismatch between hir::Item type and MonoItem type")
448 // Check for PMEs and emit a diagnostic if one happened. To try to show relevant edges of the
449 // mono item graph where the PME diagnostics are currently the most problematic (e.g. ones
450 // involving a dependency, and the lack of context is confusing) in this MVP, we focus on
451 // diagnostics on edges crossing a crate boundary: the collected mono items which are not
452 // defined in the local crate.
453 if tcx
.sess
.diagnostic().err_count() > error_count
454 && starting_point
.node
.krate() != LOCAL_CRATE
455 && starting_point
.node
.is_user_defined()
457 let formatted_item
= with_no_trimmed_paths(|| starting_point
.node
.to_string());
458 tcx
.sess
.span_note_without_error(
460 &format
!("the above error was encountered while instantiating `{}`", formatted_item
),
464 record_accesses(tcx
, starting_point
.node
, neighbors
.iter().map(|i
| &i
.node
), inlining_map
);
466 for neighbour
in neighbors
{
467 collect_items_rec(tcx
, neighbour
, visited
, recursion_depths
, recursion_limit
, inlining_map
);
470 if let Some((def_id
, depth
)) = recursion_depth_reset
{
471 recursion_depths
.insert(def_id
, depth
);
474 debug
!("END collect_items_rec({})", starting_point
.node
);
477 fn record_accesses
<'a
, 'tcx
: 'a
>(
479 caller
: MonoItem
<'tcx
>,
480 callees
: impl Iterator
<Item
= &'a MonoItem
<'tcx
>>,
481 inlining_map
: MTRef
<'_
, MTLock
<InliningMap
<'tcx
>>>,
483 let is_inlining_candidate
= |mono_item
: &MonoItem
<'tcx
>| {
484 mono_item
.instantiation_mode(tcx
) == InstantiationMode
::LocalCopy
487 // We collect this into a `SmallVec` to avoid calling `is_inlining_candidate` in the lock.
488 // FIXME: Call `is_inlining_candidate` when pushing to `neighbors` in `collect_items_rec`
489 // instead to avoid creating this `SmallVec`.
490 let accesses
: SmallVec
<[_
; 128]> =
491 callees
.map(|mono_item
| (*mono_item
, is_inlining_candidate(mono_item
))).collect();
493 inlining_map
.lock_mut().record_accesses(caller
, &accesses
);
496 /// Format instance name that is already known to be too long for rustc.
497 /// Show only the first and last 32 characters to avoid blasting
498 /// the user's terminal with thousands of lines of type-name.
500 /// If the type name is longer than before+after, it will be written to a file.
501 fn shrunk_instance_name(
503 instance
: &Instance
<'tcx
>,
506 ) -> (String
, Option
<PathBuf
>) {
507 let s
= instance
.to_string();
509 // Only use the shrunk version if it's really shorter.
510 // This also avoids the case where before and after slices overlap.
511 if s
.chars().nth(before
+ after
+ 1).is_some() {
512 // An iterator of all byte positions including the end of the string.
513 let positions
= || s
.char_indices().map(|(i
, _
)| i
).chain(iter
::once(s
.len()));
515 let shrunk
= format
!(
516 "{before}...{after}",
517 before
= &s
[..positions().nth(before
).unwrap_or(s
.len())],
518 after
= &s
[positions().rev().nth(after
).unwrap_or(0)..],
521 let path
= tcx
.output_filenames(()).temp_path_ext("long-type.txt", None
);
522 let written_to_path
= std
::fs
::write(&path
, s
).ok().map(|_
| path
);
524 (shrunk
, written_to_path
)
530 fn check_recursion_limit
<'tcx
>(
532 instance
: Instance
<'tcx
>,
534 recursion_depths
: &mut DefIdMap
<usize>,
535 recursion_limit
: Limit
,
536 ) -> (DefId
, usize) {
537 let def_id
= instance
.def_id();
538 let recursion_depth
= recursion_depths
.get(&def_id
).cloned().unwrap_or(0);
539 debug
!(" => recursion depth={}", recursion_depth
);
541 let adjusted_recursion_depth
= if Some(def_id
) == tcx
.lang_items().drop_in_place_fn() {
542 // HACK: drop_in_place creates tight monomorphization loops. Give
549 // Code that needs to instantiate the same function recursively
550 // more than the recursion limit is assumed to be causing an
551 // infinite expansion.
552 if !recursion_limit
.value_within_limit(adjusted_recursion_depth
) {
553 let (shrunk
, written_to_path
) = shrunk_instance_name(tcx
, &instance
, 32, 32);
554 let error
= format
!("reached the recursion limit while instantiating `{}`", shrunk
);
555 let mut err
= tcx
.sess
.struct_span_fatal(span
, &error
);
557 tcx
.def_span(def_id
),
558 &format
!("`{}` defined here", tcx
.def_path_str(def_id
)),
560 if let Some(path
) = written_to_path
{
561 err
.note(&format
!("the full type name has been written to '{}'", path
.display()));
567 recursion_depths
.insert(def_id
, recursion_depth
+ 1);
569 (def_id
, recursion_depth
)
572 fn check_type_length_limit
<'tcx
>(tcx
: TyCtxt
<'tcx
>, instance
: Instance
<'tcx
>) {
573 let type_length
= instance
576 .flat_map(|arg
| arg
.walk(tcx
))
577 .filter(|arg
| match arg
.unpack() {
578 GenericArgKind
::Type(_
) | GenericArgKind
::Const(_
) => true,
579 GenericArgKind
::Lifetime(_
) => false,
582 debug
!(" => type length={}", type_length
);
584 // Rust code can easily create exponentially-long types using only a
585 // polynomial recursion depth. Even with the default recursion
586 // depth, you can easily get cases that take >2^60 steps to run,
587 // which means that rustc basically hangs.
589 // Bail out in these cases to avoid that bad user experience.
590 if !tcx
.type_length_limit().value_within_limit(type_length
) {
591 let (shrunk
, written_to_path
) = shrunk_instance_name(tcx
, &instance
, 32, 32);
592 let msg
= format
!("reached the type-length limit while instantiating `{}`", shrunk
);
593 let mut diag
= tcx
.sess
.struct_span_fatal(tcx
.def_span(instance
.def_id()), &msg
);
594 if let Some(path
) = written_to_path
{
595 diag
.note(&format
!("the full type name has been written to '{}'", path
.display()));
598 "consider adding a `#![type_length_limit=\"{}\"]` attribute to your crate",
602 tcx
.sess
.abort_if_errors();
606 struct MirNeighborCollector
<'a
, 'tcx
> {
608 body
: &'a mir
::Body
<'tcx
>,
609 output
: &'a
mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
610 instance
: Instance
<'tcx
>,
613 impl<'a
, 'tcx
> MirNeighborCollector
<'a
, 'tcx
> {
614 pub fn monomorphize
<T
>(&self, value
: T
) -> T
616 T
: TypeFoldable
<'tcx
>,
618 debug
!("monomorphize: self.instance={:?}", self.instance
);
619 self.instance
.subst_mir_and_normalize_erasing_regions(
621 ty
::ParamEnv
::reveal_all(),
627 impl<'a
, 'tcx
> MirVisitor
<'tcx
> for MirNeighborCollector
<'a
, 'tcx
> {
628 fn visit_rvalue(&mut self, rvalue
: &mir
::Rvalue
<'tcx
>, location
: Location
) {
629 debug
!("visiting rvalue {:?}", *rvalue
);
631 let span
= self.body
.source_info(location
).span
;
634 // When doing an cast from a regular pointer to a fat pointer, we
635 // have to instantiate all methods of the trait being cast to, so we
636 // can build the appropriate vtable.
638 mir
::CastKind
::Pointer(PointerCast
::Unsize
),
642 let target_ty
= self.monomorphize(target_ty
);
643 let source_ty
= operand
.ty(self.body
, self.tcx
);
644 let source_ty
= self.monomorphize(source_ty
);
645 let (source_ty
, target_ty
) =
646 find_vtable_types_for_unsizing(self.tcx
, source_ty
, target_ty
);
647 // This could also be a different Unsize instruction, like
648 // from a fixed sized array to a slice. But we are only
649 // interested in things that produce a vtable.
650 if target_ty
.is_trait() && !source_ty
.is_trait() {
651 create_mono_items_for_vtable_methods(
661 mir
::CastKind
::Pointer(PointerCast
::ReifyFnPointer
),
665 let fn_ty
= operand
.ty(self.body
, self.tcx
);
666 let fn_ty
= self.monomorphize(fn_ty
);
667 visit_fn_use(self.tcx
, fn_ty
, false, span
, &mut self.output
);
670 mir
::CastKind
::Pointer(PointerCast
::ClosureFnPointer(_
)),
674 let source_ty
= operand
.ty(self.body
, self.tcx
);
675 let source_ty
= self.monomorphize(source_ty
);
676 match *source_ty
.kind() {
677 ty
::Closure(def_id
, substs
) => {
678 let instance
= Instance
::resolve_closure(
682 ty
::ClosureKind
::FnOnce
,
684 if should_codegen_locally(self.tcx
, &instance
) {
685 self.output
.push(create_fn_mono_item(self.tcx
, instance
, span
));
691 mir
::Rvalue
::NullaryOp(mir
::NullOp
::Box
, _
) => {
693 let exchange_malloc_fn_def_id
=
694 tcx
.require_lang_item(LangItem
::ExchangeMalloc
, None
);
695 let instance
= Instance
::mono(tcx
, exchange_malloc_fn_def_id
);
696 if should_codegen_locally(tcx
, &instance
) {
697 self.output
.push(create_fn_mono_item(self.tcx
, instance
, span
));
700 mir
::Rvalue
::ThreadLocalRef(def_id
) => {
701 assert
!(self.tcx
.is_thread_local_static(def_id
));
702 let instance
= Instance
::mono(self.tcx
, def_id
);
703 if should_codegen_locally(self.tcx
, &instance
) {
704 trace
!("collecting thread-local static {:?}", def_id
);
705 self.output
.push(respan(span
, MonoItem
::Static(def_id
)));
708 _
=> { /* not interesting */ }
711 self.super_rvalue(rvalue
, location
);
714 /// This does not walk the constant, as it has been handled entirely here and trying
715 /// to walk it would attempt to evaluate the `ty::Const` inside, which doesn't necessarily
716 /// work, as some constants cannot be represented in the type system.
717 fn visit_constant(&mut self, constant
: &mir
::Constant
<'tcx
>, location
: Location
) {
718 let literal
= self.monomorphize(constant
.literal
);
719 let val
= match literal
{
720 mir
::ConstantKind
::Val(val
, _
) => val
,
721 mir
::ConstantKind
::Ty(ct
) => match ct
.val
{
722 ty
::ConstKind
::Value(val
) => val
,
723 ty
::ConstKind
::Unevaluated(ct
) => {
724 let param_env
= ty
::ParamEnv
::reveal_all();
725 match self.tcx
.const_eval_resolve(param_env
, ct
, None
) {
726 // The `monomorphize` call should have evaluated that constant already.
728 Err(ErrorHandled
::Reported(ErrorReported
) | ErrorHandled
::Linted
) => return,
729 Err(ErrorHandled
::TooGeneric
) => span_bug
!(
730 self.body
.source_info(location
).span
,
731 "collection encountered polymorphic constant: {:?}",
739 collect_const_value(self.tcx
, val
, self.output
);
740 self.visit_ty(literal
.ty(), TyContext
::Location(location
));
743 fn visit_const(&mut self, constant
: &&'tcx ty
::Const
<'tcx
>, location
: Location
) {
744 debug
!("visiting const {:?} @ {:?}", *constant
, location
);
746 let substituted_constant
= self.monomorphize(*constant
);
747 let param_env
= ty
::ParamEnv
::reveal_all();
749 match substituted_constant
.val
{
750 ty
::ConstKind
::Value(val
) => collect_const_value(self.tcx
, val
, self.output
),
751 ty
::ConstKind
::Unevaluated(unevaluated
) => {
752 match self.tcx
.const_eval_resolve(param_env
, unevaluated
, None
) {
753 // The `monomorphize` call should have evaluated that constant already.
754 Ok(val
) => span_bug
!(
755 self.body
.source_info(location
).span
,
756 "collection encountered the unevaluated constant {} which evaluated to {:?}",
757 substituted_constant
,
760 Err(ErrorHandled
::Reported(ErrorReported
) | ErrorHandled
::Linted
) => {}
761 Err(ErrorHandled
::TooGeneric
) => span_bug
!(
762 self.body
.source_info(location
).span
,
763 "collection encountered polymorphic constant: {}",
771 self.super_const(constant
);
774 fn visit_terminator(&mut self, terminator
: &mir
::Terminator
<'tcx
>, location
: Location
) {
775 debug
!("visiting terminator {:?} @ {:?}", terminator
, location
);
776 let source
= self.body
.source_info(location
).span
;
779 match terminator
.kind
{
780 mir
::TerminatorKind
::Call { ref func, .. }
=> {
781 let callee_ty
= func
.ty(self.body
, tcx
);
782 let callee_ty
= self.monomorphize(callee_ty
);
783 visit_fn_use(self.tcx
, callee_ty
, true, source
, &mut self.output
);
785 mir
::TerminatorKind
::Drop { ref place, .. }
786 | mir
::TerminatorKind
::DropAndReplace { ref place, .. }
=> {
787 let ty
= place
.ty(self.body
, self.tcx
).ty
;
788 let ty
= self.monomorphize(ty
);
789 visit_drop_use(self.tcx
, ty
, true, source
, self.output
);
791 mir
::TerminatorKind
::InlineAsm { ref operands, .. }
=> {
794 mir
::InlineAsmOperand
::SymFn { ref value }
=> {
795 let fn_ty
= self.monomorphize(value
.literal
.ty());
796 visit_fn_use(self.tcx
, fn_ty
, false, source
, &mut self.output
);
798 mir
::InlineAsmOperand
::SymStatic { def_id }
=> {
799 let instance
= Instance
::mono(self.tcx
, def_id
);
800 if should_codegen_locally(self.tcx
, &instance
) {
801 trace
!("collecting asm sym static {:?}", def_id
);
802 self.output
.push(respan(source
, MonoItem
::Static(def_id
)));
809 mir
::TerminatorKind
::Goto { .. }
810 | mir
::TerminatorKind
::SwitchInt { .. }
811 | mir
::TerminatorKind
::Resume
812 | mir
::TerminatorKind
::Abort
813 | mir
::TerminatorKind
::Return
814 | mir
::TerminatorKind
::Unreachable
815 | mir
::TerminatorKind
::Assert { .. }
=> {}
816 mir
::TerminatorKind
::GeneratorDrop
817 | mir
::TerminatorKind
::Yield { .. }
818 | mir
::TerminatorKind
::FalseEdge { .. }
819 | mir
::TerminatorKind
::FalseUnwind { .. }
=> bug
!(),
822 self.super_terminator(terminator
, location
);
825 fn visit_operand(&mut self, operand
: &mir
::Operand
<'tcx
>, location
: Location
) {
826 self.super_operand(operand
, location
);
827 let limit
= self.tcx
.move_size_limit().0;
831 let limit
= Size
::from_bytes(limit
);
832 let ty
= operand
.ty(self.body
, self.tcx
);
833 let ty
= self.monomorphize(ty
);
834 let layout
= self.tcx
.layout_of(ty
::ParamEnv
::reveal_all().and(ty
));
835 if let Ok(layout
) = layout
{
836 if layout
.size
> limit
{
838 let source_info
= self.body
.source_info(location
);
839 debug
!(?source_info
);
840 let lint_root
= source_info
.scope
.lint_root(&self.body
.source_scopes
);
842 let lint_root
= match lint_root
{
843 Some(lint_root
) => lint_root
,
844 // This happens when the issue is in a function from a foreign crate that
845 // we monomorphized in the current crate. We can't get a `HirId` for things
847 // FIXME: Find out where to report the lint on. Maybe simply crate-level lint root
848 // but correct span? This would make the lint at least accept crate-level lint attributes.
851 self.tcx
.struct_span_lint_hir(
856 let mut err
= lint
.build(&format
!("moving {} bytes", layout
.size
.bytes()));
857 err
.span_label(source_info
.span
, "value moved from here");
867 _place_local
: &Local
,
868 _context
: mir
::visit
::PlaceContext
,
874 fn visit_drop_use
<'tcx
>(
877 is_direct_call
: bool
,
879 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
881 let instance
= Instance
::resolve_drop_in_place(tcx
, ty
);
882 visit_instance_use(tcx
, instance
, is_direct_call
, source
, output
);
885 fn visit_fn_use
<'tcx
>(
888 is_direct_call
: bool
,
890 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
892 if let ty
::FnDef(def_id
, substs
) = *ty
.kind() {
893 let instance
= if is_direct_call
{
894 ty
::Instance
::resolve(tcx
, ty
::ParamEnv
::reveal_all(), def_id
, substs
).unwrap().unwrap()
896 ty
::Instance
::resolve_for_fn_ptr(tcx
, ty
::ParamEnv
::reveal_all(), def_id
, substs
)
899 visit_instance_use(tcx
, instance
, is_direct_call
, source
, output
);
903 fn visit_instance_use
<'tcx
>(
905 instance
: ty
::Instance
<'tcx
>,
906 is_direct_call
: bool
,
908 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
910 debug
!("visit_item_use({:?}, is_direct_call={:?})", instance
, is_direct_call
);
911 if !should_codegen_locally(tcx
, &instance
) {
916 ty
::InstanceDef
::Virtual(..) | ty
::InstanceDef
::Intrinsic(_
) => {
918 bug
!("{:?} being reified", instance
);
921 ty
::InstanceDef
::DropGlue(_
, None
) => {
922 // Don't need to emit noop drop glue if we are calling directly.
924 output
.push(create_fn_mono_item(tcx
, instance
, source
));
927 ty
::InstanceDef
::DropGlue(_
, Some(_
))
928 | ty
::InstanceDef
::VtableShim(..)
929 | ty
::InstanceDef
::ReifyShim(..)
930 | ty
::InstanceDef
::ClosureOnceShim { .. }
931 | ty
::InstanceDef
::Item(..)
932 | ty
::InstanceDef
::FnPtrShim(..)
933 | ty
::InstanceDef
::CloneShim(..) => {
934 output
.push(create_fn_mono_item(tcx
, instance
, source
));
939 /// Returns `true` if we should codegen an instance in the local crate, or returns `false` if we
940 /// can just link to the upstream crate and therefore don't need a mono item.
941 fn should_codegen_locally
<'tcx
>(tcx
: TyCtxt
<'tcx
>, instance
: &Instance
<'tcx
>) -> bool
{
942 let def_id
= if let Some(def_id
) = instance
.def
.def_id_if_not_guaranteed_local_codegen() {
948 if tcx
.is_foreign_item(def_id
) {
949 // Foreign items are always linked against, there's no way of instantiating them.
953 if def_id
.is_local() {
954 // Local items cannot be referred to locally without monomorphizing them locally.
958 if tcx
.is_reachable_non_generic(def_id
)
959 || instance
.polymorphize(tcx
).upstream_monomorphization(tcx
).is_some()
961 // We can link to the item in question, no instance needed in this crate.
965 if !tcx
.is_mir_available(def_id
) {
966 bug
!("no MIR available for {:?}", def_id
);
972 /// For a given pair of source and target type that occur in an unsizing coercion,
973 /// this function finds the pair of types that determines the vtable linking
976 /// For example, the source type might be `&SomeStruct` and the target type\
977 /// might be `&SomeTrait` in a cast like:
979 /// let src: &SomeStruct = ...;
980 /// let target = src as &SomeTrait;
982 /// Then the output of this function would be (SomeStruct, SomeTrait) since for
983 /// constructing the `target` fat-pointer we need the vtable for that pair.
985 /// Things can get more complicated though because there's also the case where
986 /// the unsized type occurs as a field:
989 /// struct ComplexStruct<T: ?Sized> {
996 /// In this case, if `T` is sized, `&ComplexStruct<T>` is a thin pointer. If `T`
997 /// is unsized, `&SomeStruct` is a fat pointer, and the vtable it points to is
998 /// for the pair of `T` (which is a trait) and the concrete type that `T` was
999 /// originally coerced from:
1001 /// let src: &ComplexStruct<SomeStruct> = ...;
1002 /// let target = src as &ComplexStruct<SomeTrait>;
1004 /// Again, we want this `find_vtable_types_for_unsizing()` to provide the pair
1005 /// `(SomeStruct, SomeTrait)`.
1007 /// Finally, there is also the case of custom unsizing coercions, e.g., for
1008 /// smart pointers such as `Rc` and `Arc`.
1009 fn find_vtable_types_for_unsizing
<'tcx
>(
1011 source_ty
: Ty
<'tcx
>,
1012 target_ty
: Ty
<'tcx
>,
1013 ) -> (Ty
<'tcx
>, Ty
<'tcx
>) {
1014 let ptr_vtable
= |inner_source
: Ty
<'tcx
>, inner_target
: Ty
<'tcx
>| {
1015 let param_env
= ty
::ParamEnv
::reveal_all();
1016 let type_has_metadata
= |ty
: Ty
<'tcx
>| -> bool
{
1017 if ty
.is_sized(tcx
.at(DUMMY_SP
), param_env
) {
1020 let tail
= tcx
.struct_tail_erasing_lifetimes(ty
, param_env
);
1022 ty
::Foreign(..) => false,
1023 ty
::Str
| ty
::Slice(..) | ty
::Dynamic(..) => true,
1024 _
=> bug
!("unexpected unsized tail: {:?}", tail
),
1027 if type_has_metadata(inner_source
) {
1028 (inner_source
, inner_target
)
1030 tcx
.struct_lockstep_tails_erasing_lifetimes(inner_source
, inner_target
, param_env
)
1034 match (&source_ty
.kind(), &target_ty
.kind()) {
1035 (&ty
::Ref(_
, a
, _
), &ty
::Ref(_
, b
, _
) | &ty
::RawPtr(ty
::TypeAndMut { ty: b, .. }
))
1036 | (&ty
::RawPtr(ty
::TypeAndMut { ty: a, .. }
), &ty
::RawPtr(ty
::TypeAndMut { ty: b, .. }
)) => {
1039 (&ty
::Adt(def_a
, _
), &ty
::Adt(def_b
, _
)) if def_a
.is_box() && def_b
.is_box() => {
1040 ptr_vtable(source_ty
.boxed_ty(), target_ty
.boxed_ty())
1043 (&ty
::Adt(source_adt_def
, source_substs
), &ty
::Adt(target_adt_def
, target_substs
)) => {
1044 assert_eq
!(source_adt_def
, target_adt_def
);
1046 let CustomCoerceUnsized
::Struct(coerce_index
) =
1047 crate::custom_coerce_unsize_info(tcx
, source_ty
, target_ty
);
1049 let source_fields
= &source_adt_def
.non_enum_variant().fields
;
1050 let target_fields
= &target_adt_def
.non_enum_variant().fields
;
1053 coerce_index
< source_fields
.len() && source_fields
.len() == target_fields
.len()
1056 find_vtable_types_for_unsizing(
1058 source_fields
[coerce_index
].ty(tcx
, source_substs
),
1059 target_fields
[coerce_index
].ty(tcx
, target_substs
),
1063 "find_vtable_types_for_unsizing: invalid coercion {:?} -> {:?}",
1070 fn create_fn_mono_item
<'tcx
>(
1072 instance
: Instance
<'tcx
>,
1074 ) -> Spanned
<MonoItem
<'tcx
>> {
1075 debug
!("create_fn_mono_item(instance={})", instance
);
1077 let def_id
= instance
.def_id();
1078 if tcx
.sess
.opts
.debugging_opts
.profile_closures
&& def_id
.is_local() && tcx
.is_closure(def_id
)
1080 crate::util
::dump_closure_profile(tcx
, instance
);
1083 respan(source
, MonoItem
::Fn(instance
.polymorphize(tcx
)))
1086 /// Creates a `MonoItem` for each method that is referenced by the vtable for
1087 /// the given trait/impl pair.
1088 fn create_mono_items_for_vtable_methods
<'tcx
>(
1093 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1095 assert
!(!trait_ty
.has_escaping_bound_vars() && !impl_ty
.has_escaping_bound_vars());
1097 if let ty
::Dynamic(ref trait_ty
, ..) = trait_ty
.kind() {
1098 if let Some(principal
) = trait_ty
.principal() {
1099 let poly_trait_ref
= principal
.with_self_ty(tcx
, impl_ty
);
1100 assert
!(!poly_trait_ref
.has_escaping_bound_vars());
1102 // Walk all methods of the trait, including those of its supertraits
1103 let entries
= tcx
.vtable_entries(poly_trait_ref
);
1104 let methods
= entries
1106 .filter_map(|entry
| match entry
{
1107 VtblEntry
::MetadataDropInPlace
1108 | VtblEntry
::MetadataSize
1109 | VtblEntry
::MetadataAlign
1110 | VtblEntry
::Vacant
=> None
,
1111 VtblEntry
::TraitVPtr(_
) => {
1112 // all super trait items already covered, so skip them.
1115 VtblEntry
::Method(instance
) => {
1116 Some(*instance
).filter(|instance
| should_codegen_locally(tcx
, instance
))
1119 .map(|item
| create_fn_mono_item(tcx
, item
, source
));
1120 output
.extend(methods
);
1123 // Also add the destructor.
1124 visit_drop_use(tcx
, impl_ty
, false, source
, output
);
1128 //=-----------------------------------------------------------------------------
1130 //=-----------------------------------------------------------------------------
1132 struct RootCollector
<'a
, 'tcx
> {
1134 mode
: MonoItemCollectionMode
,
1135 output
: &'a
mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1136 entry_fn
: Option
<(DefId
, EntryFnType
)>,
1139 impl ItemLikeVisitor
<'v
> for RootCollector
<'_
, 'v
> {
1140 fn visit_item(&mut self, item
: &'v hir
::Item
<'v
>) {
1142 hir
::ItemKind
::ExternCrate(..)
1143 | hir
::ItemKind
::Use(..)
1144 | hir
::ItemKind
::Macro(..)
1145 | hir
::ItemKind
::ForeignMod { .. }
1146 | hir
::ItemKind
::TyAlias(..)
1147 | hir
::ItemKind
::Trait(..)
1148 | hir
::ItemKind
::TraitAlias(..)
1149 | hir
::ItemKind
::OpaqueTy(..)
1150 | hir
::ItemKind
::Mod(..) => {
1151 // Nothing to do, just keep recursing.
1154 hir
::ItemKind
::Impl { .. }
=> {
1155 if self.mode
== MonoItemCollectionMode
::Eager
{
1156 create_mono_items_for_default_impls(self.tcx
, item
, self.output
);
1160 hir
::ItemKind
::Enum(_
, ref generics
)
1161 | hir
::ItemKind
::Struct(_
, ref generics
)
1162 | hir
::ItemKind
::Union(_
, ref generics
) => {
1163 if generics
.params
.is_empty() {
1164 if self.mode
== MonoItemCollectionMode
::Eager
{
1166 "RootCollector: ADT drop-glue for {}",
1167 self.tcx
.def_path_str(item
.def_id
.to_def_id())
1170 let ty
= Instance
::new(item
.def_id
.to_def_id(), InternalSubsts
::empty())
1171 .ty(self.tcx
, ty
::ParamEnv
::reveal_all());
1172 visit_drop_use(self.tcx
, ty
, true, DUMMY_SP
, self.output
);
1176 hir
::ItemKind
::GlobalAsm(..) => {
1178 "RootCollector: ItemKind::GlobalAsm({})",
1179 self.tcx
.def_path_str(item
.def_id
.to_def_id())
1181 self.output
.push(dummy_spanned(MonoItem
::GlobalAsm(item
.item_id())));
1183 hir
::ItemKind
::Static(..) => {
1185 "RootCollector: ItemKind::Static({})",
1186 self.tcx
.def_path_str(item
.def_id
.to_def_id())
1188 self.output
.push(dummy_spanned(MonoItem
::Static(item
.def_id
.to_def_id())));
1190 hir
::ItemKind
::Const(..) => {
1191 // const items only generate mono items if they are
1192 // actually used somewhere. Just declaring them is insufficient.
1194 // but even just declaring them must collect the items they refer to
1195 if let Ok(val
) = self.tcx
.const_eval_poly(item
.def_id
.to_def_id()) {
1196 collect_const_value(self.tcx
, val
, &mut self.output
);
1199 hir
::ItemKind
::Fn(..) => {
1200 self.push_if_root(item
.def_id
);
1205 fn visit_trait_item(&mut self, _
: &'v hir
::TraitItem
<'v
>) {
1206 // Even if there's a default body with no explicit generics,
1207 // it's still generic over some `Self: Trait`, so not a root.
1210 fn visit_impl_item(&mut self, ii
: &'v hir
::ImplItem
<'v
>) {
1211 if let hir
::ImplItemKind
::Fn(hir
::FnSig { .. }
, _
) = ii
.kind
{
1212 self.push_if_root(ii
.def_id
);
1216 fn visit_foreign_item(&mut self, _foreign_item
: &'v hir
::ForeignItem
<'v
>) {}
1219 impl RootCollector
<'_
, 'v
> {
1220 fn is_root(&self, def_id
: LocalDefId
) -> bool
{
1221 !item_requires_monomorphization(self.tcx
, def_id
)
1222 && match self.mode
{
1223 MonoItemCollectionMode
::Eager
=> true,
1224 MonoItemCollectionMode
::Lazy
=> {
1225 self.entry_fn
.and_then(|(id
, _
)| id
.as_local()) == Some(def_id
)
1226 || self.tcx
.is_reachable_non_generic(def_id
)
1229 .codegen_fn_attrs(def_id
)
1231 .contains(CodegenFnAttrFlags
::RUSTC_STD_INTERNAL_SYMBOL
)
1236 /// If `def_id` represents a root, pushes it onto the list of
1237 /// outputs. (Note that all roots must be monomorphic.)
1238 fn push_if_root(&mut self, def_id
: LocalDefId
) {
1239 if self.is_root(def_id
) {
1240 debug
!("RootCollector::push_if_root: found root def_id={:?}", def_id
);
1242 let instance
= Instance
::mono(self.tcx
, def_id
.to_def_id());
1243 self.output
.push(create_fn_mono_item(self.tcx
, instance
, DUMMY_SP
));
1247 /// As a special case, when/if we encounter the
1248 /// `main()` function, we also have to generate a
1249 /// monomorphized copy of the start lang item based on
1250 /// the return type of `main`. This is not needed when
1251 /// the user writes their own `start` manually.
1252 fn push_extra_entry_roots(&mut self) {
1253 let main_def_id
= match self.entry_fn
{
1254 Some((def_id
, EntryFnType
::Main
)) => def_id
,
1258 let start_def_id
= match self.tcx
.lang_items().require(LangItem
::Start
) {
1260 Err(err
) => self.tcx
.sess
.fatal(&err
),
1262 let main_ret_ty
= self.tcx
.fn_sig(main_def_id
).output();
1264 // Given that `main()` has no arguments,
1265 // then its return type cannot have
1266 // late-bound regions, since late-bound
1267 // regions must appear in the argument
1269 let main_ret_ty
= self.tcx
.erase_regions(main_ret_ty
.no_bound_vars().unwrap());
1271 let start_instance
= Instance
::resolve(
1273 ty
::ParamEnv
::reveal_all(),
1275 self.tcx
.intern_substs(&[main_ret_ty
.into()]),
1280 self.output
.push(create_fn_mono_item(self.tcx
, start_instance
, DUMMY_SP
));
1284 fn item_requires_monomorphization(tcx
: TyCtxt
<'_
>, def_id
: LocalDefId
) -> bool
{
1285 let generics
= tcx
.generics_of(def_id
);
1286 generics
.requires_monomorphization(tcx
)
1289 fn create_mono_items_for_default_impls
<'tcx
>(
1291 item
: &'tcx hir
::Item
<'tcx
>,
1292 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1295 hir
::ItemKind
::Impl(ref impl_
) => {
1296 for param
in impl_
.generics
.params
{
1298 hir
::GenericParamKind
::Lifetime { .. }
=> {}
1299 hir
::GenericParamKind
::Type { .. }
| hir
::GenericParamKind
::Const { .. }
=> {
1306 "create_mono_items_for_default_impls(item={})",
1307 tcx
.def_path_str(item
.def_id
.to_def_id())
1310 if let Some(trait_ref
) = tcx
.impl_trait_ref(item
.def_id
) {
1311 let param_env
= ty
::ParamEnv
::reveal_all();
1312 let trait_ref
= tcx
.normalize_erasing_regions(param_env
, trait_ref
);
1313 let overridden_methods
: FxHashSet
<_
> =
1314 impl_
.items
.iter().map(|iiref
| iiref
.ident
.normalize_to_macros_2_0()).collect();
1315 for method
in tcx
.provided_trait_methods(trait_ref
.def_id
) {
1316 if overridden_methods
.contains(&method
.ident
.normalize_to_macros_2_0()) {
1320 if tcx
.generics_of(method
.def_id
).own_requires_monomorphization() {
1325 InternalSubsts
::for_item(tcx
, method
.def_id
, |param
, _
| match param
.kind
{
1326 GenericParamDefKind
::Lifetime
=> tcx
.lifetimes
.re_erased
.into(),
1327 GenericParamDefKind
::Type { .. }
1328 | GenericParamDefKind
::Const { .. }
=> {
1329 trait_ref
.substs
[param
.index
as usize]
1332 let instance
= ty
::Instance
::resolve(tcx
, param_env
, method
.def_id
, substs
)
1336 let mono_item
= create_fn_mono_item(tcx
, instance
, DUMMY_SP
);
1337 if mono_item
.node
.is_instantiable(tcx
) && should_codegen_locally(tcx
, &instance
)
1339 output
.push(mono_item
);
1348 /// Scans the miri alloc in order to find function calls, closures, and drop-glue.
1349 fn collect_miri
<'tcx
>(
1352 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1354 match tcx
.global_alloc(alloc_id
) {
1355 GlobalAlloc
::Static(def_id
) => {
1356 assert
!(!tcx
.is_thread_local_static(def_id
));
1357 let instance
= Instance
::mono(tcx
, def_id
);
1358 if should_codegen_locally(tcx
, &instance
) {
1359 trace
!("collecting static {:?}", def_id
);
1360 output
.push(dummy_spanned(MonoItem
::Static(def_id
)));
1363 GlobalAlloc
::Memory(alloc
) => {
1364 trace
!("collecting {:?} with {:#?}", alloc_id
, alloc
);
1365 for &inner
in alloc
.relocations().values() {
1366 rustc_data_structures
::stack
::ensure_sufficient_stack(|| {
1367 collect_miri(tcx
, inner
, output
);
1371 GlobalAlloc
::Function(fn_instance
) => {
1372 if should_codegen_locally(tcx
, &fn_instance
) {
1373 trace
!("collecting {:?} with {:#?}", alloc_id
, fn_instance
);
1374 output
.push(create_fn_mono_item(tcx
, fn_instance
, DUMMY_SP
));
1380 /// Scans the MIR in order to find function calls, closures, and drop-glue.
1381 fn collect_neighbours
<'tcx
>(
1383 instance
: Instance
<'tcx
>,
1384 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1386 debug
!("collect_neighbours: {:?}", instance
.def_id());
1387 let body
= tcx
.instance_mir(instance
.def
);
1389 MirNeighborCollector { tcx, body: &body, output, instance }
.visit_body(&body
);
1392 fn collect_const_value
<'tcx
>(
1394 value
: ConstValue
<'tcx
>,
1395 output
: &mut Vec
<Spanned
<MonoItem
<'tcx
>>>,
1398 ConstValue
::Scalar(Scalar
::Ptr(ptr
, _size
)) => collect_miri(tcx
, ptr
.provenance
, output
),
1399 ConstValue
::Slice { data: alloc, start: _, end: _ }
| ConstValue
::ByRef { alloc, .. }
=> {
1400 for &id
in alloc
.relocations().values() {
1401 collect_miri(tcx
, id
, output
);