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::ErrorGuaranteed;
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;
20 use rustc_target::spec::abi::Abi;
24 crate fn mir_built<'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);
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()));
38 tcx.alloc_steal_mir(body)
41 /// Construct the MIR for a given `DefId`.
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);
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.
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)));
56 ty::WithOptConstParam { did, const_param_did: None } => {
57 tcx.ensure().thir_check_unsafety(did);
58 drop(tcx.thir_abstract_const(did));
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)
67 Node::Item(hir::Item {
68 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
72 | Node::ImplItem(hir::ImplItem {
73 kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id),
77 | Node::TraitItem(hir::TraitItem {
78 kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)),
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))
86 Node::Item(hir::Item {
87 kind: hir::ItemKind::Static(ty, _, body_id) | hir::ItemKind::Const(ty, body_id),
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)),
94 }) => (*body_id, ty.span, None),
95 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
96 (*body, tcx.hir().span(*hir_id), None)
99 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def.did),
102 // If we don't have a specialized span for the body, just use the
104 let span_with_body = span_with_body.unwrap_or_else(|| tcx.hir().span(id));
106 tcx.infer_ctxt().enter(|infcx| {
107 let body = if let Some(error_reported) = typeck_results.tainted_by_errors {
108 build::construct_error(&infcx, def, id, body_id, body_owner_kind, error_reported)
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);
115 let safety = match fn_sig.unsafety {
116 hir::Unsafety::Normal => Safety::Safe,
117 hir::Unsafety::Unsafe => Safety::FnUnsafe,
120 let body = tcx.hir().body(body_id);
121 let (thir, expr) = tcx
123 .unwrap_or_else(|_| (tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0)));
124 // We ran all queries that depended on THIR at the beginning
125 // of `mir_build`, so now we can steal it
126 let thir = thir.steal();
127 let ty = tcx.type_of(fn_def_id);
128 let mut abi = fn_sig.abi;
129 let implicit_argument = match ty.kind() {
131 // HACK(eddyb) Avoid having RustCall on closures,
132 // as it adds unnecessary (and wrong) auto-tupling.
134 vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)]
136 ty::Generator(..) => {
137 let gen_ty = tcx.typeck_body(body_id).node_type(id);
139 // The resume argument may be missing, in that case we need to provide it here.
140 // It will always be `()` in this case.
141 if body.params.is_empty() {
143 ArgInfo(gen_ty, None, None, None),
144 ArgInfo(tcx.mk_unit(), None, None, None),
147 vec![ArgInfo(gen_ty, None, None, None)]
153 let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| {
154 let owner_id = tcx.hir().body_owner(body_id);
157 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
158 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
159 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
160 match fn_decl.implicit_self {
161 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
162 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
163 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
164 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
175 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
176 // (as it's created inside the body itself, not passed in from outside).
177 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
178 let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(arg.span));
180 tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()])
182 fn_sig.inputs()[index]
185 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
188 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
190 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
191 let gen_ty = tcx.typeck_body(body_id).node_type(id);
192 let gen_sig = match gen_ty.kind() {
193 ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(),
194 _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty),
196 (Some(gen_sig.yield_ty), gen_sig.return_ty)
198 (None, fn_sig.output())
201 let mut mir = build::construct_fn(
215 if yield_ty.is_some() {
216 mir.generator.as_mut().unwrap().yield_ty = yield_ty;
220 // Get the revealed type of this const. This is *not* the adjusted
221 // type of its body, which may be a subtype of this type. For
225 // static X: fn(&'static ()) = foo;
227 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
228 // is not the same as the type of X. We need the type of the return
229 // place to be the type of the constant because NLL typeck will
232 let return_ty = typeck_results.node_type(id);
234 let (thir, expr) = tcx
236 .unwrap_or_else(|_| (tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0)));
237 // We ran all queries that depended on THIR at the beginning
238 // of `mir_build`, so now we can steal it
239 let thir = thir.steal();
241 build::construct_const(&thir, &infcx, expr, def, id, return_ty, return_ty_span)
244 lints::check(tcx, &body);
246 // The borrow checker will replace all the regions here with its own
247 // inference variables. There's no point having non-erased regions here.
248 // The exception is `body.user_type_annotations`, which is used unmodified
249 // by borrow checking.
251 !(body.local_decls.has_free_regions()
252 || body.basic_blocks().has_free_regions()
253 || body.var_debug_info.has_free_regions()
254 || body.yield_ty().has_free_regions()),
255 "Unexpected free regions in MIR: {:?}",
263 ///////////////////////////////////////////////////////////////////////////
264 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
266 fn liberated_closure_env_ty(
268 closure_expr_id: hir::HirId,
269 body_id: hir::BodyId,
271 let closure_ty = tcx.typeck_body(body_id).node_type(closure_expr_id);
273 let ty::Closure(closure_def_id, closure_substs) = *closure_ty.kind() else {
274 bug!("closure expr does not have closure type: {:?}", closure_ty);
278 tcx.mk_bound_variable_kinds(std::iter::once(ty::BoundVariableKind::Region(ty::BrEnv)));
280 ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind: ty::BrEnv };
281 let env_region = ty::ReLateBound(ty::INNERMOST, br);
282 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
283 tcx.erase_late_bound_regions(ty::Binder::bind_with_vars(closure_env_ty, bound_vars))
286 #[derive(Debug, PartialEq, Eq)]
288 /// Evaluation is currently within a statement.
290 /// Examples include:
292 /// 2. `let _ = EXPR;`
293 /// 3. `let x = EXPR;`
295 /// If true, then statement discards result from evaluating
296 /// the expression (such as examples 1 and 2 above).
297 ignores_expr_result: bool,
300 /// Evaluation is currently within the tail expression of a block.
302 /// Example: `{ STMT_1; STMT_2; EXPR }`
304 /// If true, then the surrounding context of the block ignores
305 /// the result of evaluating the block's tail expression.
307 /// Example: `let _ = { STMT_1; EXPR };`
308 tail_result_is_ignored: bool,
310 /// `Span` of the tail expression.
314 /// Generic mark meaning that the block occurred as a subexpression
315 /// where the result might be used.
317 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
322 fn is_tail_expr(&self) -> bool {
324 BlockFrame::TailExpr { .. } => true,
326 BlockFrame::Statement { .. } | BlockFrame::SubExpr => false,
329 fn is_statement(&self) -> bool {
331 BlockFrame::Statement { .. } => true,
333 BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false,
339 struct BlockContext(Vec<BlockFrame>);
341 struct Builder<'a, 'tcx> {
343 infcx: &'a InferCtxt<'a, 'tcx>,
344 typeck_results: &'tcx TypeckResults<'tcx>,
345 region_scope_tree: &'tcx region::ScopeTree,
346 param_env: ty::ParamEnv<'tcx>,
348 thir: &'a Thir<'tcx>,
353 check_overflow: bool,
356 generator_kind: Option<GeneratorKind>,
358 /// The current set of scopes, updated as we traverse;
359 /// see the `scope` module for more details.
360 scopes: scope::Scopes<'tcx>,
362 /// The block-context: each time we build the code within an thir::Block,
363 /// we push a frame here tracking whether we are building a statement or
364 /// if we are pushing the tail expression of the block. This is used to
365 /// embed information in generated temps about whether they were created
366 /// for a block tail expression or not.
368 /// It would be great if we could fold this into `self.scopes`
369 /// somehow, but right now I think that is very tightly tied to
370 /// the code generation in ways that we cannot (or should not)
371 /// start just throwing new entries onto that vector in order to
372 /// distinguish the context of EXPR1 from the context of EXPR2 in
373 /// `{ STMTS; EXPR1 } + EXPR2`.
374 block_context: BlockContext,
376 /// The current unsafe block in scope
377 in_scope_unsafe: Safety,
379 /// The vector of all scopes that we have created thus far;
380 /// we track this for debuginfo later.
381 source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
382 source_scope: SourceScope,
384 /// The guard-context: each time we build the guard expression for
385 /// a match arm, we push onto this stack, and then pop when we
386 /// finish building it.
387 guard_context: Vec<GuardFrame>,
389 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
390 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
391 var_indices: HirIdMap<LocalsForNode>,
392 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
393 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
394 upvar_mutbls: Vec<Mutability>,
395 unit_temp: Option<Place<'tcx>>,
397 var_debug_info: Vec<VarDebugInfo<'tcx>>,
400 impl<'a, 'tcx> Builder<'a, 'tcx> {
401 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
402 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
405 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
406 self.var_indices[&id].local_id(for_guard)
414 fn push(&mut self, bf: BlockFrame) {
417 fn pop(&mut self) -> Option<BlockFrame> {
421 /// Traverses the frames on the `BlockContext`, searching for either
422 /// the first block-tail expression frame with no intervening
425 /// Notably, this skips over `SubExpr` frames; this method is
426 /// meant to be used in the context of understanding the
427 /// relationship of a temp (created within some complicated
428 /// expression) with its containing expression, and whether the
429 /// value of that *containing expression* (not the temp!) is
431 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
432 for bf in self.0.iter().rev() {
434 BlockFrame::SubExpr => continue,
435 BlockFrame::Statement { .. } => break,
436 &BlockFrame::TailExpr { tail_result_is_ignored, span } => {
437 return Some(BlockTailInfo { tail_result_is_ignored, span });
445 /// Looks at the topmost frame on the BlockContext and reports
446 /// whether its one that would discard a block tail result.
448 /// Unlike `currently_within_ignored_tail_expression`, this does
449 /// *not* skip over `SubExpr` frames: here, we want to know
450 /// whether the block result itself is discarded.
451 fn currently_ignores_tail_results(&self) -> bool {
452 match self.0.last() {
453 // no context: conservatively assume result is read
456 // sub-expression: block result feeds into some computation
457 Some(BlockFrame::SubExpr) => false,
459 // otherwise: use accumulated is_ignored state.
461 BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. }
462 | BlockFrame::Statement { ignores_expr_result: ignored },
470 /// In the usual case, a `HirId` for an identifier maps to at most
471 /// one `Local` declaration.
474 /// The exceptional case is identifiers in a match arm's pattern
475 /// that are referenced in a guard of that match arm. For these,
476 /// we have `2` Locals.
478 /// * `for_arm_body` is the Local used in the arm body (which is
479 /// just like the `One` case above),
481 /// * `ref_for_guard` is the Local used in the arm's guard (which
482 /// is a reference to a temp that is an alias of
484 ForGuard { ref_for_guard: Local, for_arm_body: Local },
488 struct GuardFrameLocal {
492 impl GuardFrameLocal {
493 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
494 GuardFrameLocal { id }
500 /// These are the id's of names that are bound by patterns of the
501 /// arm of *this* guard.
503 /// (Frames higher up the stack will have the id's bound in arms
504 /// further out, such as in a case like:
507 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
510 /// here, when building for FIXME.
511 locals: Vec<GuardFrameLocal>,
514 /// `ForGuard` indicates whether we are talking about:
515 /// 1. The variable for use outside of guard expressions, or
516 /// 2. The temp that holds reference to (1.), which is actually what the
517 /// guard expressions see.
518 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
525 fn local_id(&self, for_guard: ForGuard) -> Local {
526 match (self, for_guard) {
527 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard)
529 &LocalsForNode::ForGuard { ref_for_guard: local_id, .. },
530 ForGuard::RefWithinGuard,
532 | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => {
536 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => {
537 bug!("anything with one local should never be within a guard.")
544 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
547 rustc_index::newtype_index! {
548 struct ScopeId { .. }
551 ///////////////////////////////////////////////////////////////////////////
552 /// The `BlockAnd` "monad" packages up the new basic block along with a
553 /// produced value (sometimes just unit, of course). The `unpack!`
554 /// macro (and methods below) makes working with `BlockAnd` much more
557 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
558 struct BlockAnd<T>(BasicBlock, T);
560 trait BlockAndExtension {
561 fn and<T>(self, v: T) -> BlockAnd<T>;
562 fn unit(self) -> BlockAnd<()>;
565 impl BlockAndExtension for BasicBlock {
566 fn and<T>(self, v: T) -> BlockAnd<T> {
570 fn unit(self) -> BlockAnd<()> {
575 /// Update a block pointer and return the value.
576 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
577 macro_rules! unpack {
578 ($x:ident = $c:expr) => {{
579 let BlockAnd(b, v) = $c;
585 let BlockAnd(b, ()) = $c;
590 ///////////////////////////////////////////////////////////////////////////
591 /// the main entry point for building MIR for a function
593 struct ArgInfo<'tcx>(
596 Option<&'tcx hir::Param<'tcx>>,
597 Option<ImplicitSelfKind>,
600 fn construct_fn<'tcx, A>(
602 infcx: &InferCtxt<'_, 'tcx>,
603 fn_def: ty::WithOptConstParam<LocalDefId>,
609 return_ty_span: Span,
610 body: &'tcx hir::Body<'tcx>,
612 span_with_body: Span,
615 A: Iterator<Item = ArgInfo<'tcx>>,
617 let arguments: Vec<_> = arguments.collect();
620 let span = tcx.hir().span(fn_id);
622 let mut builder = Builder::new(
635 let call_site_scope =
636 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite };
638 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments };
639 let source_info = builder.source_info(span);
640 let call_site_s = (call_site_scope, source_info);
641 unpack!(builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
642 let arg_scope_s = (arg_scope, source_info);
643 // Attribute epilogue to function's closing brace
644 let fn_end = span_with_body.shrink_to_hi();
646 unpack!(builder.in_breakable_scope(None, Place::return_place(), fn_end, |builder| {
647 Some(builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
648 builder.args_and_body(
650 fn_def.did.to_def_id(),
657 let source_info = builder.source_info(fn_end);
658 builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
659 builder.build_drop_trees();
663 let spread_arg = if abi == Abi::RustCall {
664 // RustCall pseudo-ABI untuples the last argument.
665 Some(Local::new(arguments.len()))
669 debug!("fn_id {:?} has attrs {:?}", fn_def, tcx.get_attrs(fn_def.did.to_def_id()));
671 let mut body = builder.finish();
672 body.spread_arg = spread_arg;
676 fn construct_const<'a, 'tcx>(
677 thir: &'a Thir<'tcx>,
678 infcx: &'a InferCtxt<'a, 'tcx>,
680 def: ty::WithOptConstParam<LocalDefId>,
686 let span = tcx.hir().span(hir_id);
687 let mut builder = Builder::new(
700 let mut block = START_BLOCK;
701 unpack!(block = builder.expr_into_dest(Place::return_place(), block, &thir[expr]));
703 let source_info = builder.source_info(span);
704 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
706 builder.build_drop_trees();
711 /// Construct MIR for an item that has had errors in type checking.
713 /// This is required because we may still want to run MIR passes on an item
714 /// with type errors, but normal MIR construction can't handle that in general.
715 fn construct_error<'a, 'tcx>(
716 infcx: &'a InferCtxt<'a, 'tcx>,
717 def: ty::WithOptConstParam<LocalDefId>,
719 body_id: hir::BodyId,
720 body_owner_kind: hir::BodyOwnerKind,
721 err: ErrorGuaranteed,
724 let span = tcx.hir().span(hir_id);
725 let ty = tcx.ty_error();
726 let generator_kind = tcx.hir().body(body_id).generator_kind;
727 let num_params = match body_owner_kind {
728 hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len(),
729 hir::BodyOwnerKind::Closure => {
730 if generator_kind.is_some() {
731 // Generators have an implicit `self` parameter *and* a possibly
732 // implicit resume parameter.
735 // The implicit self parameter adds another local in MIR.
736 1 + tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len()
739 hir::BodyOwnerKind::Const => 0,
740 hir::BodyOwnerKind::Static(_) => 0,
742 let mut cfg = CFG { basic_blocks: IndexVec::new() };
743 let mut source_scopes = IndexVec::new();
744 let mut local_decls = IndexVec::from_elem_n(LocalDecl::new(ty, span), 1);
746 cfg.start_new_block();
747 source_scopes.push(SourceScopeData {
751 inlined_parent_scope: None,
752 local_data: ClearCrossCrate::Set(SourceScopeLocalData {
754 safety: Safety::Safe,
757 let source_info = SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE };
759 // Some MIR passes will expect the number of parameters to match the
760 // function declaration.
761 for _ in 0..num_params {
762 local_decls.push(LocalDecl::with_source_info(ty, source_info));
764 cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
766 let mut body = Body::new(
767 MirSource::item(def.did.to_def_id()),
778 body.generator.as_mut().map(|gen| gen.yield_ty = Some(ty));
782 impl<'a, 'tcx> Builder<'a, 'tcx> {
784 thir: &'a Thir<'tcx>,
785 infcx: &'a InferCtxt<'a, 'tcx>,
786 def: ty::WithOptConstParam<LocalDefId>,
793 generator_kind: Option<GeneratorKind>,
794 ) -> Builder<'a, 'tcx> {
796 let attrs = tcx.hir().attrs(hir_id);
797 // Some functions always have overflow checks enabled,
798 // however, they may not get codegen'd, depending on
799 // the settings for the crate they are codegened in.
800 let mut check_overflow = tcx.sess.contains_name(attrs, sym::rustc_inherit_overflow_checks);
801 // Respect -C overflow-checks.
802 check_overflow |= tcx.sess.overflow_checks();
803 // Constants always need overflow checks.
804 check_overflow |= matches!(
805 tcx.hir().body_owner_kind(hir_id),
806 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_)
809 let lint_level = LintLevel::Explicit(hir_id);
810 let mut builder = Builder {
814 typeck_results: tcx.typeck_opt_const_arg(def),
815 region_scope_tree: tcx.region_scope_tree(def.did),
816 param_env: tcx.param_env(def.did),
817 def_id: def.did.to_def_id(),
820 cfg: CFG { basic_blocks: IndexVec::new() },
824 scopes: scope::Scopes::new(),
825 block_context: BlockContext::new(),
826 source_scopes: IndexVec::new(),
827 source_scope: OUTERMOST_SOURCE_SCOPE,
828 guard_context: vec![],
829 in_scope_unsafe: safety,
830 local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1),
831 canonical_user_type_annotations: IndexVec::new(),
832 upvar_mutbls: vec![],
833 var_indices: Default::default(),
835 var_debug_info: vec![],
838 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
840 builder.new_source_scope(span, lint_level, Some(safety)),
841 OUTERMOST_SOURCE_SCOPE
843 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
848 fn finish(self) -> Body<'tcx> {
849 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
850 if block.terminator.is_none() {
851 span_bug!(self.fn_span, "no terminator on block {:?}", index);
856 MirSource::item(self.def_id),
857 self.cfg.basic_blocks,
860 self.canonical_user_type_annotations,
865 self.typeck_results.tainted_by_errors,
871 mut block: BasicBlock,
873 arguments: &[ArgInfo<'tcx>],
874 argument_scope: region::Scope,
877 // Allocate locals for the function arguments
878 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
880 SourceInfo::outermost(arg_opt.map_or(self.fn_span, |arg| arg.pat.span));
881 let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info));
883 // If this is a simple binding pattern, give debuginfo a nice name.
884 if let Some(arg) = arg_opt && let Some(ident) = arg.pat.simple_ident() {
885 self.var_debug_info.push(VarDebugInfo {
888 value: VarDebugInfoContents::Place(arg_local.into()),
894 let tcx_hir = tcx.hir();
895 let hir_typeck_results = self.typeck_results;
897 // In analyze_closure() in upvar.rs we gathered a list of upvars used by an
898 // indexed closure and we stored in a map called closure_min_captures in TypeckResults
899 // with the closure's DefId. Here, we run through that vec of UpvarIds for
900 // the given closure and use the necessary information to create upvar
901 // debuginfo and to fill `self.upvar_mutbls`.
902 if hir_typeck_results.closure_min_captures.get(&fn_def_id).is_some() {
903 let mut closure_env_projs = vec![];
904 let mut closure_ty = self.local_decls[ty::CAPTURE_STRUCT_LOCAL].ty;
905 if let ty::Ref(_, ty, _) = closure_ty.kind() {
906 closure_env_projs.push(ProjectionElem::Deref);
909 let upvar_substs = match closure_ty.kind() {
910 ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
911 ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
912 _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
914 let def_id = self.def_id.as_local().unwrap();
915 let capture_syms = tcx.symbols_for_closure_captures((def_id, fn_def_id));
916 let capture_tys = upvar_substs.upvar_tys();
917 let captures_with_tys = hir_typeck_results
918 .closure_min_captures_flattened(fn_def_id)
919 .zip(capture_tys.zip(capture_syms));
921 self.upvar_mutbls = captures_with_tys
923 .map(|(i, (captured_place, (ty, sym)))| {
924 let capture = captured_place.info.capture_kind;
925 let var_id = match captured_place.place.base {
926 HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
927 _ => bug!("Expected an upvar"),
930 let mutability = captured_place.mutability;
932 let mut projs = closure_env_projs.clone();
933 projs.push(ProjectionElem::Field(Field::new(i), ty));
935 ty::UpvarCapture::ByValue => {}
936 ty::UpvarCapture::ByRef(..) => {
937 projs.push(ProjectionElem::Deref);
941 self.var_debug_info.push(VarDebugInfo {
943 source_info: SourceInfo::outermost(tcx_hir.span(var_id)),
944 value: VarDebugInfoContents::Place(Place {
945 local: ty::CAPTURE_STRUCT_LOCAL,
946 projection: tcx.intern_place_elems(&projs),
955 let mut scope = None;
956 // Bind the argument patterns
957 for (index, arg_info) in arguments.iter().enumerate() {
958 // Function arguments always get the first Local indices after the return place
959 let local = Local::new(index + 1);
960 let place = Place::from(local);
961 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
963 // Make sure we drop (parts of) the argument even when not matched on.
965 arg_opt.as_ref().map_or(expr.span, |arg| arg.pat.span),
971 let Some(arg) = arg_opt else {
974 let pat = match tcx.hir().get(arg.pat.hir_id) {
975 Node::Pat(pat) | Node::Binding(pat) => pat,
976 node => bug!("pattern became {:?}", node),
978 let pattern = pat_from_hir(tcx, self.param_env, self.typeck_results, pat);
979 let original_source_scope = self.source_scope;
980 let span = pattern.span;
981 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
982 match *pattern.kind {
983 // Don't introduce extra copies for simple bindings
987 mode: BindingMode::ByValue,
991 self.local_decls[local].mutability = mutability;
992 self.local_decls[local].source_info.scope = self.source_scope;
993 self.local_decls[local].local_info = if let Some(kind) = self_binding {
994 Some(Box::new(LocalInfo::User(ClearCrossCrate::Set(
995 BindingForm::ImplicitSelf(*kind),
998 let binding_mode = ty::BindingMode::BindByValue(mutability);
999 Some(Box::new(LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
1003 opt_match_place: Some((Some(place), span)),
1008 self.var_indices.insert(var, LocalsForNode::One(local));
1011 scope = self.declare_bindings(
1015 matches::ArmHasGuard(false),
1016 Some((Some(&place), span)),
1018 let place_builder = PlaceBuilder::from(local);
1019 unpack!(block = self.place_into_pattern(block, pattern, place_builder, false));
1022 self.source_scope = original_source_scope;
1025 // Enter the argument pattern bindings source scope, if it exists.
1026 if let Some(source_scope) = scope {
1027 self.source_scope = source_scope;
1030 self.expr_into_dest(Place::return_place(), block, &expr)
1033 fn set_correct_source_scope_for_arg(
1035 arg_hir_id: hir::HirId,
1036 original_source_scope: SourceScope,
1040 let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir_id);
1041 let parent_root = tcx.maybe_lint_level_root_bounded(
1042 self.source_scopes[original_source_scope]
1045 .assert_crate_local()
1049 if current_root != parent_root {
1051 self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
1055 fn get_unit_temp(&mut self) -> Place<'tcx> {
1056 match self.unit_temp {
1059 let ty = self.tcx.mk_unit();
1060 let fn_span = self.fn_span;
1061 let tmp = self.temp(ty, fn_span);
1062 self.unit_temp = Some(tmp);
1069 ///////////////////////////////////////////////////////////////////////////
1070 // Builder methods are broken up into modules, depending on what kind
1071 // of thing is being lowered. Note that they use the `unpack` macro
1072 // above extensively.
1081 pub(crate) use expr::category::Category as ExprCategory;