1 use crate::build;
2 use crate::build::expr::as_place::PlaceBuilder;
3 use crate::build::scope::DropKind;
4 use crate::thir::pattern::pat_from_hir;
5 use rustc_errors::ErrorReported;
6 use rustc_hir as hir;
7 use rustc_hir::def_id::{DefId, LocalDefId};
8 use rustc_hir::lang_items::LangItem;
9 use rustc_hir::{GeneratorKind, HirIdMap, Node};
10 use rustc_index::vec::{Idx, IndexVec};
11 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
12 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
13 use rustc_middle::middle::region;
14 use rustc_middle::mir::*;
15 use rustc_middle::thir::{BindingMode, Expr, ExprId, LintLevel, PatKind, Thir};
16 use rustc_middle::ty::subst::Subst;
17 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
18 use rustc_span::symbol::sym;
19 use rustc_span::Span;
20 use rustc_target::spec::abi::Abi;
21
22 use super::lints;
23
mir_built<'tcx>( tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>, ) -> &'tcx rustc_data_structures::steal::Steal<Body<'tcx>>24 crate fn mir_built<'tcx>(
25 tcx: TyCtxt<'tcx>,
26 def: ty::WithOptConstParam<LocalDefId>,
27 ) -> &'tcx rustc_data_structures::steal::Steal<Body<'tcx>> {
28 if let Some(def) = def.try_upgrade(tcx) {
29 return tcx.mir_built(def);
30 }
31
32 let mut body = mir_build(tcx, def);
33 if def.const_param_did.is_some() {
34 assert!(matches!(body.source.instance, ty::InstanceDef::Item(_)));
35 body.source = MirSource::from_instance(ty::InstanceDef::Item(def.to_global()));
36 }
37
38 tcx.alloc_steal_mir(body)
39 }
40
41 /// Construct the MIR for a given `DefId`.
mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_>42 fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
43 let id = tcx.hir().local_def_id_to_hir_id(def.did);
44 let body_owner_kind = tcx.hir().body_owner_kind(id);
45 let typeck_results = tcx.typeck_opt_const_arg(def);
46
47 // Ensure unsafeck and abstract const building is ran before we steal the THIR.
48 // We can't use `ensure()` for `thir_abstract_const` as it doesn't compute the query
49 // if inputs are green. This can cause ICEs when calling `thir_abstract_const` after
50 // THIR has been stolen if we haven't computed this query yet.
51 match def {
52 ty::WithOptConstParam { did, const_param_did: Some(const_param_did) } => {
53 tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did));
54 drop(tcx.thir_abstract_const_of_const_arg((did, const_param_did)));
55 }
56 ty::WithOptConstParam { did, const_param_did: None } => {
57 tcx.ensure().thir_check_unsafety(did);
58 drop(tcx.thir_abstract_const(did));
59 }
60 }
61
62 // Figure out what primary body this item has.
63 let (body_id, return_ty_span, span_with_body) = match tcx.hir().get(id) {
64 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. }) => {
65 (*body_id, decl.output.span(), None)
66 }
67 Node::Item(hir::Item {
68 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
69 span,
70 ..
71 })
72 | Node::ImplItem(hir::ImplItem {
73 kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id),
74 span,
75 ..
76 })
77 | Node::TraitItem(hir::TraitItem {
78 kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)),
79 span,
80 ..
81 }) => {
82 // Use the `Span` of the `Item/ImplItem/TraitItem` as the body span,
83 // since the def span of a function does not include the body
84 (*body_id, decl.output.span(), Some(*span))
85 }
86 Node::Item(hir::Item {
87 kind: hir::ItemKind::Static(ty, _, body_id) | hir::ItemKind::Const(ty, body_id),
88 ..
89 })
90 | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. })
91 | Node::TraitItem(hir::TraitItem {
92 kind: hir::TraitItemKind::Const(ty, Some(body_id)),
93 ..
94 }) => (*body_id, ty.span, None),
95 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
96 (*body, tcx.hir().span(*hir_id), None)
97 }
98
99 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def.did),
100 };
101
102 // If we don't have a specialized span for the body, just use the
103 // normal def span.
104 let span_with_body = span_with_body.unwrap_or_else(|| tcx.hir().span(id));
105
106 tcx.infer_ctxt().enter(|infcx| {
107 let body = if let Some(ErrorReported) = typeck_results.tainted_by_errors {
108 build::construct_error(&infcx, def, id, body_id, body_owner_kind)
109 } else if body_owner_kind.is_fn_or_closure() {
110 // fetch the fully liberated fn signature (that is, all bound
111 // types/lifetimes replaced)
112 let fn_sig = typeck_results.liberated_fn_sigs()[id];
113 let fn_def_id = tcx.hir().local_def_id(id);
114
115 let safety = match fn_sig.unsafety {
116 hir::Unsafety::Normal => Safety::Safe,
117 hir::Unsafety::Unsafe => Safety::FnUnsafe,
118 };
119
120 let body = tcx.hir().body(body_id);
121 let (thir, expr) = tcx.thir_body(def);
122 // We ran all queries that depended on THIR at the beginning
123 // of `mir_build`, so now we can steal it
124 let thir = thir.steal();
125 let ty = tcx.type_of(fn_def_id);
126 let mut abi = fn_sig.abi;
127 let implicit_argument = match ty.kind() {
128 ty::Closure(..) => {
129 // HACK(eddyb) Avoid having RustCall on closures,
130 // as it adds unnecessary (and wrong) auto-tupling.
131 abi = Abi::Rust;
132 vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)]
133 }
134 ty::Generator(..) => {
135 let gen_ty = tcx.typeck_body(body_id).node_type(id);
136
137 // The resume argument may be missing, in that case we need to provide it here.
138 // It will always be `()` in this case.
139 if body.params.is_empty() {
140 vec![
141 ArgInfo(gen_ty, None, None, None),
142 ArgInfo(tcx.mk_unit(), None, None, None),
143 ]
144 } else {
145 vec![ArgInfo(gen_ty, None, None, None)]
146 }
147 }
148 _ => vec![],
149 };
150
151 let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| {
152 let owner_id = tcx.hir().body_owner(body_id);
153 let opt_ty_info;
154 let self_arg;
155 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
156 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
157 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
158 match fn_decl.implicit_self {
159 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
160 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
161 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
162 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
163 _ => None,
164 }
165 } else {
166 None
167 };
168 } else {
169 opt_ty_info = None;
170 self_arg = None;
171 }
172
173 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
174 // (as it's created inside the body itself, not passed in from outside).
175 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
176 let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(arg.span));
177
178 tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()])
179 } else {
180 fn_sig.inputs()[index]
181 };
182
183 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
184 });
185
186 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
187
188 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
189 let gen_ty = tcx.typeck_body(body_id).node_type(id);
190 let gen_sig = match gen_ty.kind() {
191 ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(),
192 _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty),
193 };
194 (Some(gen_sig.yield_ty), gen_sig.return_ty)
195 } else {
196 (None, fn_sig.output())
197 };
198
199 let mut mir = build::construct_fn(
200 &thir,
201 &infcx,
202 def,
203 id,
204 arguments,
205 safety,
206 abi,
207 return_ty,
208 return_ty_span,
209 body,
210 expr,
211 span_with_body,
212 );
213 if yield_ty.is_some() {
214 mir.generator.as_mut().unwrap().yield_ty = yield_ty;
215 }
216 mir
217 } else {
218 // Get the revealed type of this const. This is *not* the adjusted
219 // type of its body, which may be a subtype of this type. For
220 // example:
221 //
222 // fn foo(_: &()) {}
223 // static X: fn(&'static ()) = foo;
224 //
225 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
226 // is not the same as the type of X. We need the type of the return
227 // place to be the type of the constant because NLL typeck will
228 // equate them.
229
230 let return_ty = typeck_results.node_type(id);
231
232 let (thir, expr) = tcx.thir_body(def);
233 // We ran all queries that depended on THIR at the beginning
234 // of `mir_build`, so now we can steal it
235 let thir = thir.steal();
236
237 build::construct_const(&thir, &infcx, expr, def, id, return_ty, return_ty_span)
238 };
239
240 lints::check(tcx, &body);
241
242 // The borrow checker will replace all the regions here with its own
243 // inference variables. There's no point having non-erased regions here.
244 // The exception is `body.user_type_annotations`, which is used unmodified
245 // by borrow checking.
246 debug_assert!(
247 !(body.local_decls.has_free_regions(tcx)
248 || body.basic_blocks().has_free_regions(tcx)
249 || body.var_debug_info.has_free_regions(tcx)
250 || body.yield_ty().has_free_regions(tcx)),
251 "Unexpected free regions in MIR: {:?}",
252 body,
253 );
254
255 body
256 })
257 }
258
259 ///////////////////////////////////////////////////////////////////////////
260 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
261
liberated_closure_env_ty( tcx: TyCtxt<'_>, closure_expr_id: hir::HirId, body_id: hir::BodyId, ) -> Ty<'_>262 fn liberated_closure_env_ty(
263 tcx: TyCtxt<'_>,
264 closure_expr_id: hir::HirId,
265 body_id: hir::BodyId,
266 ) -> Ty<'_> {
267 let closure_ty = tcx.typeck_body(body_id).node_type(closure_expr_id);
268
269 let (closure_def_id, closure_substs) = match *closure_ty.kind() {
270 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
271 _ => bug!("closure expr does not have closure type: {:?}", closure_ty),
272 };
273
274 let bound_vars =
275 tcx.mk_bound_variable_kinds(std::iter::once(ty::BoundVariableKind::Region(ty::BrEnv)));
276 let br =
277 ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind: ty::BrEnv };
278 let env_region = ty::ReLateBound(ty::INNERMOST, br);
279 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
280 tcx.erase_late_bound_regions(ty::Binder::bind_with_vars(closure_env_ty, bound_vars))
281 }
282
283 #[derive(Debug, PartialEq, Eq)]
284 enum BlockFrame {
285 /// Evaluation is currently within a statement.
286 ///
287 /// Examples include:
288 /// 1. `EXPR;`
289 /// 2. `let _ = EXPR;`
290 /// 3. `let x = EXPR;`
291 Statement {
292 /// If true, then statement discards result from evaluating
293 /// the expression (such as examples 1 and 2 above).
294 ignores_expr_result: bool,
295 },
296
297 /// Evaluation is currently within the tail expression of a block.
298 ///
299 /// Example: `{ STMT_1; STMT_2; EXPR }`
300 TailExpr {
301 /// If true, then the surrounding context of the block ignores
302 /// the result of evaluating the block's tail expression.
303 ///
304 /// Example: `let _ = { STMT_1; EXPR };`
305 tail_result_is_ignored: bool,
306
307 /// `Span` of the tail expression.
308 span: Span,
309 },
310
311 /// Generic mark meaning that the block occurred as a subexpression
312 /// where the result might be used.
313 ///
314 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
315 SubExpr,
316 }
317
318 impl BlockFrame {
is_tail_expr(&self) -> bool319 fn is_tail_expr(&self) -> bool {
320 match *self {
321 BlockFrame::TailExpr { .. } => true,
322
323 BlockFrame::Statement { .. } | BlockFrame::SubExpr => false,
324 }
325 }
is_statement(&self) -> bool326 fn is_statement(&self) -> bool {
327 match *self {
328 BlockFrame::Statement { .. } => true,
329
330 BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false,
331 }
332 }
333 }
334
335 #[derive(Debug)]
336 struct BlockContext(Vec<BlockFrame>);
337
338 struct Builder<'a, 'tcx> {
339 tcx: TyCtxt<'tcx>,
340 infcx: &'a InferCtxt<'a, 'tcx>,
341 typeck_results: &'tcx TypeckResults<'tcx>,
342 region_scope_tree: &'tcx region::ScopeTree,
343 param_env: ty::ParamEnv<'tcx>,
344
345 thir: &'a Thir<'tcx>,
346 cfg: CFG<'tcx>,
347
348 def_id: DefId,
349 hir_id: hir::HirId,
350 check_overflow: bool,
351 fn_span: Span,
352 arg_count: usize,
353 generator_kind: Option<GeneratorKind>,
354
355 /// The current set of scopes, updated as we traverse;
356 /// see the `scope` module for more details.
357 scopes: scope::Scopes<'tcx>,
358
359 /// The block-context: each time we build the code within an thir::Block,
360 /// we push a frame here tracking whether we are building a statement or
361 /// if we are pushing the tail expression of the block. This is used to
362 /// embed information in generated temps about whether they were created
363 /// for a block tail expression or not.
364 ///
365 /// It would be great if we could fold this into `self.scopes`
366 /// somehow, but right now I think that is very tightly tied to
367 /// the code generation in ways that we cannot (or should not)
368 /// start just throwing new entries onto that vector in order to
369 /// distinguish the context of EXPR1 from the context of EXPR2 in
370 /// `{ STMTS; EXPR1 } + EXPR2`.
371 block_context: BlockContext,
372
373 /// The current unsafe block in scope
374 in_scope_unsafe: Safety,
375
376 /// The vector of all scopes that we have created thus far;
377 /// we track this for debuginfo later.
378 source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
379 source_scope: SourceScope,
380
381 /// The guard-context: each time we build the guard expression for
382 /// a match arm, we push onto this stack, and then pop when we
383 /// finish building it.
384 guard_context: Vec<GuardFrame>,
385
386 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
387 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
388 var_indices: HirIdMap<LocalsForNode>,
389 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
390 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
391 upvar_mutbls: Vec<Mutability>,
392 unit_temp: Option<Place<'tcx>>,
393
394 var_debug_info: Vec<VarDebugInfo<'tcx>>,
395 }
396
397 impl<'a, 'tcx> Builder<'a, 'tcx> {
is_bound_var_in_guard(&self, id: hir::HirId) -> bool398 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
399 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
400 }
401
var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local402 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
403 self.var_indices[&id].local_id(for_guard)
404 }
405 }
406
407 impl BlockContext {
new() -> Self408 fn new() -> Self {
409 BlockContext(vec![])
410 }
push(&mut self, bf: BlockFrame)411 fn push(&mut self, bf: BlockFrame) {
412 self.0.push(bf);
413 }
pop(&mut self) -> Option<BlockFrame>414 fn pop(&mut self) -> Option<BlockFrame> {
415 self.0.pop()
416 }
417
418 /// Traverses the frames on the `BlockContext`, searching for either
419 /// the first block-tail expression frame with no intervening
420 /// statement frame.
421 ///
422 /// Notably, this skips over `SubExpr` frames; this method is
423 /// meant to be used in the context of understanding the
424 /// relationship of a temp (created within some complicated
425 /// expression) with its containing expression, and whether the
426 /// value of that *containing expression* (not the temp!) is
427 /// ignored.
currently_in_block_tail(&self) -> Option<BlockTailInfo>428 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
429 for bf in self.0.iter().rev() {
430 match bf {
431 BlockFrame::SubExpr => continue,
432 BlockFrame::Statement { .. } => break,
433 &BlockFrame::TailExpr { tail_result_is_ignored, span } => {
434 return Some(BlockTailInfo { tail_result_is_ignored, span });
435 }
436 }
437 }
438
439 None
440 }
441
442 /// Looks at the topmost frame on the BlockContext and reports
443 /// whether its one that would discard a block tail result.
444 ///
445 /// Unlike `currently_within_ignored_tail_expression`, this does
446 /// *not* skip over `SubExpr` frames: here, we want to know
447 /// whether the block result itself is discarded.
currently_ignores_tail_results(&self) -> bool448 fn currently_ignores_tail_results(&self) -> bool {
449 match self.0.last() {
450 // no context: conservatively assume result is read
451 None => false,
452
453 // sub-expression: block result feeds into some computation
454 Some(BlockFrame::SubExpr) => false,
455
456 // otherwise: use accumulated is_ignored state.
457 Some(
458 BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. }
459 | BlockFrame::Statement { ignores_expr_result: ignored },
460 ) => *ignored,
461 }
462 }
463 }
464
465 #[derive(Debug)]
466 enum LocalsForNode {
467 /// In the usual case, a `HirId` for an identifier maps to at most
468 /// one `Local` declaration.
469 One(Local),
470
471 /// The exceptional case is identifiers in a match arm's pattern
472 /// that are referenced in a guard of that match arm. For these,
473 /// we have `2` Locals.
474 ///
475 /// * `for_arm_body` is the Local used in the arm body (which is
476 /// just like the `One` case above),
477 ///
478 /// * `ref_for_guard` is the Local used in the arm's guard (which
479 /// is a reference to a temp that is an alias of
480 /// `for_arm_body`).
481 ForGuard { ref_for_guard: Local, for_arm_body: Local },
482 }
483
484 #[derive(Debug)]
485 struct GuardFrameLocal {
486 id: hir::HirId,
487 }
488
489 impl GuardFrameLocal {
new(id: hir::HirId, _binding_mode: BindingMode) -> Self490 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
491 GuardFrameLocal { id }
492 }
493 }
494
495 #[derive(Debug)]
496 struct GuardFrame {
497 /// These are the id's of names that are bound by patterns of the
498 /// arm of *this* guard.
499 ///
500 /// (Frames higher up the stack will have the id's bound in arms
501 /// further out, such as in a case like:
502 ///
503 /// match E1 {
504 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
505 /// }
506 ///
507 /// here, when building for FIXME.
508 locals: Vec<GuardFrameLocal>,
509 }
510
511 /// `ForGuard` indicates whether we are talking about:
512 /// 1. The variable for use outside of guard expressions, or
513 /// 2. The temp that holds reference to (1.), which is actually what the
514 /// guard expressions see.
515 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
516 enum ForGuard {
517 RefWithinGuard,
518 OutsideGuard,
519 }
520
521 impl LocalsForNode {
local_id(&self, for_guard: ForGuard) -> Local522 fn local_id(&self, for_guard: ForGuard) -> Local {
523 match (self, for_guard) {
524 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard)
525 | (
526 &LocalsForNode::ForGuard { ref_for_guard: local_id, .. },
527 ForGuard::RefWithinGuard,
528 )
529 | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => {
530 local_id
531 }
532
533 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => {
534 bug!("anything with one local should never be within a guard.")
535 }
536 }
537 }
538 }
539
540 struct CFG<'tcx> {
541 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
542 }
543
544 rustc_index::newtype_index! {
545 struct ScopeId { .. }
546 }
547
548 ///////////////////////////////////////////////////////////////////////////
549 /// The `BlockAnd` "monad" packages up the new basic block along with a
550 /// produced value (sometimes just unit, of course). The `unpack!`
551 /// macro (and methods below) makes working with `BlockAnd` much more
552 /// convenient.
553
554 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
555 struct BlockAnd<T>(BasicBlock, T);
556
557 trait BlockAndExtension {
and<T>(self, v: T) -> BlockAnd<T>558 fn and<T>(self, v: T) -> BlockAnd<T>;
unit(self) -> BlockAnd<()>559 fn unit(self) -> BlockAnd<()>;
560 }
561
562 impl BlockAndExtension for BasicBlock {
and<T>(self, v: T) -> BlockAnd<T>563 fn and<T>(self, v: T) -> BlockAnd<T> {
564 BlockAnd(self, v)
565 }
566
unit(self) -> BlockAnd<()>567 fn unit(self) -> BlockAnd<()> {
568 BlockAnd(self, ())
569 }
570 }
571
572 /// Update a block pointer and return the value.
573 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
574 macro_rules! unpack {
575 ($x:ident = $c:expr) => {{
576 let BlockAnd(b, v) = $c;
577 $x = b;
578 v
579 }};
580
581 ($c:expr) => {{
582 let BlockAnd(b, ()) = $c;
583 b
584 }};
585 }
586
587 ///////////////////////////////////////////////////////////////////////////
588 /// the main entry point for building MIR for a function
589
590 struct ArgInfo<'tcx>(
591 Ty<'tcx>,
592 Option<Span>,
593 Option<&'tcx hir::Param<'tcx>>,
594 Option<ImplicitSelfKind>,
595 );
596
construct_fn<'tcx, A>( thir: &Thir<'tcx>, infcx: &InferCtxt<'_, 'tcx>, fn_def: ty::WithOptConstParam<LocalDefId>, fn_id: hir::HirId, arguments: A, safety: Safety, abi: Abi, return_ty: Ty<'tcx>, return_ty_span: Span, body: &'tcx hir::Body<'tcx>, expr: ExprId, span_with_body: Span, ) -> Body<'tcx> where A: Iterator<Item = ArgInfo<'tcx>>,597 fn construct_fn<'tcx, A>(
598 thir: &Thir<'tcx>,
599 infcx: &InferCtxt<'_, 'tcx>,
600 fn_def: ty::WithOptConstParam<LocalDefId>,
601 fn_id: hir::HirId,
602 arguments: A,
603 safety: Safety,
604 abi: Abi,
605 return_ty: Ty<'tcx>,
606 return_ty_span: Span,
607 body: &'tcx hir::Body<'tcx>,
608 expr: ExprId,
609 span_with_body: Span,
610 ) -> Body<'tcx>
611 where
612 A: Iterator<Item = ArgInfo<'tcx>>,
613 {
614 let arguments: Vec<_> = arguments.collect();
615
616 let tcx = infcx.tcx;
617 let span = tcx.hir().span(fn_id);
618
619 let mut builder = Builder::new(
620 thir,
621 infcx,
622 fn_def,
623 fn_id,
624 span_with_body,
625 arguments.len(),
626 safety,
627 return_ty,
628 return_ty_span,
629 body.generator_kind,
630 );
631
632 let call_site_scope =
633 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite };
634 let arg_scope =
635 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments };
636 let source_info = builder.source_info(span);
637 let call_site_s = (call_site_scope, source_info);
638 unpack!(builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
639 let arg_scope_s = (arg_scope, source_info);
640 // Attribute epilogue to function's closing brace
641 let fn_end = span_with_body.shrink_to_hi();
642 let return_block =
643 unpack!(builder.in_breakable_scope(None, Place::return_place(), fn_end, |builder| {
644 Some(builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
645 builder.args_and_body(
646 START_BLOCK,
647 fn_def.did.to_def_id(),
648 &arguments,
649 arg_scope,
650 &thir[expr],
651 )
652 }))
653 }));
654 let source_info = builder.source_info(fn_end);
655 builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
656 builder.build_drop_trees();
657 return_block.unit()
658 }));
659
660 let spread_arg = if abi == Abi::RustCall {
661 // RustCall pseudo-ABI untuples the last argument.
662 Some(Local::new(arguments.len()))
663 } else {
664 None
665 };
666 debug!("fn_id {:?} has attrs {:?}", fn_def, tcx.get_attrs(fn_def.did.to_def_id()));
667
668 let mut body = builder.finish();
669 body.spread_arg = spread_arg;
670 body
671 }
672
construct_const<'a, 'tcx>( thir: &'a Thir<'tcx>, infcx: &'a InferCtxt<'a, 'tcx>, expr: ExprId, def: ty::WithOptConstParam<LocalDefId>, hir_id: hir::HirId, const_ty: Ty<'tcx>, const_ty_span: Span, ) -> Body<'tcx>673 fn construct_const<'a, 'tcx>(
674 thir: &'a Thir<'tcx>,
675 infcx: &'a InferCtxt<'a, 'tcx>,
676 expr: ExprId,
677 def: ty::WithOptConstParam<LocalDefId>,
678 hir_id: hir::HirId,
679 const_ty: Ty<'tcx>,
680 const_ty_span: Span,
681 ) -> Body<'tcx> {
682 let tcx = infcx.tcx;
683 let span = tcx.hir().span(hir_id);
684 let mut builder = Builder::new(
685 thir,
686 infcx,
687 def,
688 hir_id,
689 span,
690 0,
691 Safety::Safe,
692 const_ty,
693 const_ty_span,
694 None,
695 );
696
697 let mut block = START_BLOCK;
698 unpack!(block = builder.expr_into_dest(Place::return_place(), block, &thir[expr]));
699
700 let source_info = builder.source_info(span);
701 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
702
703 builder.build_drop_trees();
704
705 builder.finish()
706 }
707
708 /// Construct MIR for an item that has had errors in type checking.
709 ///
710 /// This is required because we may still want to run MIR passes on an item
711 /// with type errors, but normal MIR construction can't handle that in general.
construct_error<'a, 'tcx>( infcx: &'a InferCtxt<'a, 'tcx>, def: ty::WithOptConstParam<LocalDefId>, hir_id: hir::HirId, body_id: hir::BodyId, body_owner_kind: hir::BodyOwnerKind, ) -> Body<'tcx>712 fn construct_error<'a, 'tcx>(
713 infcx: &'a InferCtxt<'a, 'tcx>,
714 def: ty::WithOptConstParam<LocalDefId>,
715 hir_id: hir::HirId,
716 body_id: hir::BodyId,
717 body_owner_kind: hir::BodyOwnerKind,
718 ) -> Body<'tcx> {
719 let tcx = infcx.tcx;
720 let span = tcx.hir().span(hir_id);
721 let ty = tcx.ty_error();
722 let generator_kind = tcx.hir().body(body_id).generator_kind;
723 let num_params = match body_owner_kind {
724 hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len(),
725 hir::BodyOwnerKind::Closure => {
726 if generator_kind.is_some() {
727 // Generators have an implicit `self` parameter *and* a possibly
728 // implicit resume parameter.
729 2
730 } else {
731 // The implicit self parameter adds another local in MIR.
732 1 + tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len()
733 }
734 }
735 hir::BodyOwnerKind::Const => 0,
736 hir::BodyOwnerKind::Static(_) => 0,
737 };
738 let mut cfg = CFG { basic_blocks: IndexVec::new() };
739 let mut source_scopes = IndexVec::new();
740 let mut local_decls = IndexVec::from_elem_n(LocalDecl::new(ty, span), 1);
741
742 cfg.start_new_block();
743 source_scopes.push(SourceScopeData {
744 span,
745 parent_scope: None,
746 inlined: None,
747 inlined_parent_scope: None,
748 local_data: ClearCrossCrate::Set(SourceScopeLocalData {
749 lint_root: hir_id,
750 safety: Safety::Safe,
751 }),
752 });
753 let source_info = SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE };
754
755 // Some MIR passes will expect the number of parameters to match the
756 // function declaration.
757 for _ in 0..num_params {
758 local_decls.push(LocalDecl::with_source_info(ty, source_info));
759 }
760 cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
761
762 let mut body = Body::new(
763 tcx,
764 MirSource::item(def.did.to_def_id()),
765 cfg.basic_blocks,
766 source_scopes,
767 local_decls,
768 IndexVec::new(),
769 num_params,
770 vec![],
771 span,
772 generator_kind,
773 );
774 body.generator.as_mut().map(|gen| gen.yield_ty = Some(ty));
775 body
776 }
777
778 impl<'a, 'tcx> Builder<'a, 'tcx> {
new( thir: &'a Thir<'tcx>, infcx: &'a InferCtxt<'a, 'tcx>, def: ty::WithOptConstParam<LocalDefId>, hir_id: hir::HirId, span: Span, arg_count: usize, safety: Safety, return_ty: Ty<'tcx>, return_span: Span, generator_kind: Option<GeneratorKind>, ) -> Builder<'a, 'tcx>779 fn new(
780 thir: &'a Thir<'tcx>,
781 infcx: &'a InferCtxt<'a, 'tcx>,
782 def: ty::WithOptConstParam<LocalDefId>,
783 hir_id: hir::HirId,
784 span: Span,
785 arg_count: usize,
786 safety: Safety,
787 return_ty: Ty<'tcx>,
788 return_span: Span,
789 generator_kind: Option<GeneratorKind>,
790 ) -> Builder<'a, 'tcx> {
791 let tcx = infcx.tcx;
792 let attrs = tcx.hir().attrs(hir_id);
793 // Some functions always have overflow checks enabled,
794 // however, they may not get codegen'd, depending on
795 // the settings for the crate they are codegened in.
796 let mut check_overflow = tcx.sess.contains_name(attrs, sym::rustc_inherit_overflow_checks);
797 // Respect -C overflow-checks.
798 check_overflow |= tcx.sess.overflow_checks();
799 // Constants always need overflow checks.
800 check_overflow |= matches!(
801 tcx.hir().body_owner_kind(hir_id),
802 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_)
803 );
804
805 let lint_level = LintLevel::Explicit(hir_id);
806 let mut builder = Builder {
807 thir,
808 tcx,
809 infcx,
810 typeck_results: tcx.typeck_opt_const_arg(def),
811 region_scope_tree: tcx.region_scope_tree(def.did),
812 param_env: tcx.param_env(def.did),
813 def_id: def.did.to_def_id(),
814 hir_id,
815 check_overflow,
816 cfg: CFG { basic_blocks: IndexVec::new() },
817 fn_span: span,
818 arg_count,
819 generator_kind,
820 scopes: scope::Scopes::new(),
821 block_context: BlockContext::new(),
822 source_scopes: IndexVec::new(),
823 source_scope: OUTERMOST_SOURCE_SCOPE,
824 guard_context: vec![],
825 in_scope_unsafe: safety,
826 local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1),
827 canonical_user_type_annotations: IndexVec::new(),
828 upvar_mutbls: vec![],
829 var_indices: Default::default(),
830 unit_temp: None,
831 var_debug_info: vec![],
832 };
833
834 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
835 assert_eq!(
836 builder.new_source_scope(span, lint_level, Some(safety)),
837 OUTERMOST_SOURCE_SCOPE
838 );
839 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
840
841 builder
842 }
843
finish(self) -> Body<'tcx>844 fn finish(self) -> Body<'tcx> {
845 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
846 if block.terminator.is_none() {
847 span_bug!(self.fn_span, "no terminator on block {:?}", index);
848 }
849 }
850
851 Body::new(
852 self.tcx,
853 MirSource::item(self.def_id),
854 self.cfg.basic_blocks,
855 self.source_scopes,
856 self.local_decls,
857 self.canonical_user_type_annotations,
858 self.arg_count,
859 self.var_debug_info,
860 self.fn_span,
861 self.generator_kind,
862 )
863 }
864
args_and_body( &mut self, mut block: BasicBlock, fn_def_id: DefId, arguments: &[ArgInfo<'tcx>], argument_scope: region::Scope, expr: &Expr<'tcx>, ) -> BlockAnd<()>865 fn args_and_body(
866 &mut self,
867 mut block: BasicBlock,
868 fn_def_id: DefId,
869 arguments: &[ArgInfo<'tcx>],
870 argument_scope: region::Scope,
871 expr: &Expr<'tcx>,
872 ) -> BlockAnd<()> {
873 // Allocate locals for the function arguments
874 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
875 let source_info =
876 SourceInfo::outermost(arg_opt.map_or(self.fn_span, |arg| arg.pat.span));
877 let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info));
878
879 // If this is a simple binding pattern, give debuginfo a nice name.
880 if let Some(arg) = arg_opt {
881 if let Some(ident) = arg.pat.simple_ident() {
882 self.var_debug_info.push(VarDebugInfo {
883 name: ident.name,
884 source_info,
885 value: VarDebugInfoContents::Place(arg_local.into()),
886 });
887 }
888 }
889 }
890
891 let tcx = self.tcx;
892 let tcx_hir = tcx.hir();
893 let hir_typeck_results = self.typeck_results;
894
895 // In analyze_closure() in upvar.rs we gathered a list of upvars used by an
896 // indexed closure and we stored in a map called closure_min_captures in TypeckResults
897 // with the closure's DefId. Here, we run through that vec of UpvarIds for
898 // the given closure and use the necessary information to create upvar
899 // debuginfo and to fill `self.upvar_mutbls`.
900 if hir_typeck_results.closure_min_captures.get(&fn_def_id).is_some() {
901 let mut closure_env_projs = vec![];
902 let mut closure_ty = self.local_decls[ty::CAPTURE_STRUCT_LOCAL].ty;
903 if let ty::Ref(_, ty, _) = closure_ty.kind() {
904 closure_env_projs.push(ProjectionElem::Deref);
905 closure_ty = ty;
906 }
907 let upvar_substs = match closure_ty.kind() {
908 ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
909 ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
910 _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
911 };
912 let def_id = self.def_id.as_local().unwrap();
913 let capture_syms = tcx.symbols_for_closure_captures((def_id, fn_def_id));
914 let capture_tys = upvar_substs.upvar_tys();
915 let captures_with_tys = hir_typeck_results
916 .closure_min_captures_flattened(fn_def_id)
917 .zip(capture_tys.zip(capture_syms));
918
919 self.upvar_mutbls = captures_with_tys
920 .enumerate()
921 .map(|(i, (captured_place, (ty, sym)))| {
922 let capture = captured_place.info.capture_kind;
923 let var_id = match captured_place.place.base {
924 HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
925 _ => bug!("Expected an upvar"),
926 };
927
928 let mutability = captured_place.mutability;
929
930 let mut projs = closure_env_projs.clone();
931 projs.push(ProjectionElem::Field(Field::new(i), ty));
932 match capture {
933 ty::UpvarCapture::ByValue(_) => {}
934 ty::UpvarCapture::ByRef(..) => {
935 projs.push(ProjectionElem::Deref);
936 }
937 };
938
939 self.var_debug_info.push(VarDebugInfo {
940 name: sym,
941 source_info: SourceInfo::outermost(tcx_hir.span(var_id)),
942 value: VarDebugInfoContents::Place(Place {
943 local: ty::CAPTURE_STRUCT_LOCAL,
944 projection: tcx.intern_place_elems(&projs),
945 }),
946 });
947
948 mutability
949 })
950 .collect();
951 }
952
953 let mut scope = None;
954 // Bind the argument patterns
955 for (index, arg_info) in arguments.iter().enumerate() {
956 // Function arguments always get the first Local indices after the return place
957 let local = Local::new(index + 1);
958 let place = Place::from(local);
959 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
960
961 // Make sure we drop (parts of) the argument even when not matched on.
962 self.schedule_drop(
963 arg_opt.as_ref().map_or(expr.span, |arg| arg.pat.span),
964 argument_scope,
965 local,
966 DropKind::Value,
967 );
968
969 let Some(arg) = arg_opt else {
970 continue;
971 };
972 let pat = match tcx.hir().get(arg.pat.hir_id) {
973 Node::Pat(pat) | Node::Binding(pat) => pat,
974 node => bug!("pattern became {:?}", node),
975 };
976 let pattern = pat_from_hir(tcx, self.param_env, self.typeck_results, pat);
977 let original_source_scope = self.source_scope;
978 let span = pattern.span;
979 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
980 match *pattern.kind {
981 // Don't introduce extra copies for simple bindings
982 PatKind::Binding {
983 mutability,
984 var,
985 mode: BindingMode::ByValue,
986 subpattern: None,
987 ..
988 } => {
989 self.local_decls[local].mutability = mutability;
990 self.local_decls[local].source_info.scope = self.source_scope;
991 self.local_decls[local].local_info = if let Some(kind) = self_binding {
992 Some(Box::new(LocalInfo::User(ClearCrossCrate::Set(
993 BindingForm::ImplicitSelf(*kind),
994 ))))
995 } else {
996 let binding_mode = ty::BindingMode::BindByValue(mutability);
997 Some(Box::new(LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
998 VarBindingForm {
999 binding_mode,
1000 opt_ty_info,
1001 opt_match_place: Some((Some(place), span)),
1002 pat_span: span,
1003 },
1004 )))))
1005 };
1006 self.var_indices.insert(var, LocalsForNode::One(local));
1007 }
1008 _ => {
1009 scope = self.declare_bindings(
1010 scope,
1011 expr.span,
1012 &pattern,
1013 matches::ArmHasGuard(false),
1014 Some((Some(&place), span)),
1015 );
1016 let place_builder = PlaceBuilder::from(local);
1017 unpack!(block = self.place_into_pattern(block, pattern, place_builder, false));
1018 }
1019 }
1020 self.source_scope = original_source_scope;
1021 }
1022
1023 // Enter the argument pattern bindings source scope, if it exists.
1024 if let Some(source_scope) = scope {
1025 self.source_scope = source_scope;
1026 }
1027
1028 self.expr_into_dest(Place::return_place(), block, &expr)
1029 }
1030
set_correct_source_scope_for_arg( &mut self, arg_hir_id: hir::HirId, original_source_scope: SourceScope, pattern_span: Span, )1031 fn set_correct_source_scope_for_arg(
1032 &mut self,
1033 arg_hir_id: hir::HirId,
1034 original_source_scope: SourceScope,
1035 pattern_span: Span,
1036 ) {
1037 let tcx = self.tcx;
1038 let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir_id);
1039 let parent_root = tcx.maybe_lint_level_root_bounded(
1040 self.source_scopes[original_source_scope]
1041 .local_data
1042 .as_ref()
1043 .assert_crate_local()
1044 .lint_root,
1045 self.hir_id,
1046 );
1047 if current_root != parent_root {
1048 self.source_scope =
1049 self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
1050 }
1051 }
1052
get_unit_temp(&mut self) -> Place<'tcx>1053 fn get_unit_temp(&mut self) -> Place<'tcx> {
1054 match self.unit_temp {
1055 Some(tmp) => tmp,
1056 None => {
1057 let ty = self.tcx.mk_unit();
1058 let fn_span = self.fn_span;
1059 let tmp = self.temp(ty, fn_span);
1060 self.unit_temp = Some(tmp);
1061 tmp
1062 }
1063 }
1064 }
1065 }
1066
1067 ///////////////////////////////////////////////////////////////////////////
1068 // Builder methods are broken up into modules, depending on what kind
1069 // of thing is being lowered. Note that they use the `unpack` macro
1070 // above extensively.
1071
1072 mod block;
1073 mod cfg;
1074 mod expr;
1075 mod matches;
1076 mod misc;
1077 mod scope;
1078
1079 pub(crate) use expr::category::Category as ExprCategory;
1080