2 use crate::build::scope::DropKind;
3 use crate::thir::cx::build_thir;
4 use crate::thir::{Arena, BindingMode, Expr, LintLevel, Pat, PatKind};
5 use rustc_attr::{self as attr, UnwindAttr};
6 use rustc_errors::ErrorReported;
8 use rustc_hir::def_id::{DefId, LocalDefId};
9 use rustc_hir::lang_items::LangItem;
10 use rustc_hir::{GeneratorKind, HirIdMap, Node};
11 use rustc_index::vec::{Idx, IndexVec};
12 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
13 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
14 use rustc_middle::middle::region;
15 use rustc_middle::mir::*;
16 use rustc_middle::ty::subst::Subst;
17 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
18 use rustc_span::symbol::{kw, sym};
20 use rustc_target::spec::abi::Abi;
21 use rustc_target::spec::PanicStrategy;
25 crate fn mir_built<'tcx>(
27 def: ty::WithOptConstParam<LocalDefId>,
28 ) -> &'tcx rustc_data_structures::steal::Steal<Body<'tcx>> {
29 if let Some(def) = def.try_upgrade(tcx) {
30 return tcx.mir_built(def);
33 let mut body = mir_build(tcx, def);
34 if def.const_param_did.is_some() {
35 assert!(matches!(body.source.instance, ty::InstanceDef::Item(_)));
36 body.source = MirSource::from_instance(ty::InstanceDef::Item(def.to_global()));
39 tcx.alloc_steal_mir(body)
42 /// Construct the MIR for a given `DefId`.
43 fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
44 let id = tcx.hir().local_def_id_to_hir_id(def.did);
45 let body_owner_kind = tcx.hir().body_owner_kind(id);
46 let typeck_results = tcx.typeck_opt_const_arg(def);
48 // Figure out what primary body this item has.
49 let (body_id, return_ty_span, span_with_body) = match tcx.hir().get(id) {
50 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. }) => {
51 (*body_id, decl.output.span(), None)
53 Node::Item(hir::Item {
54 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
58 | Node::ImplItem(hir::ImplItem {
59 kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id),
63 | Node::TraitItem(hir::TraitItem {
64 kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)),
68 // Use the `Span` of the `Item/ImplItem/TraitItem` as the body span,
69 // since the def span of a function does not include the body
70 (*body_id, decl.output.span(), Some(*span))
72 Node::Item(hir::Item {
73 kind: hir::ItemKind::Static(ty, _, body_id) | hir::ItemKind::Const(ty, body_id),
76 | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. })
77 | Node::TraitItem(hir::TraitItem {
78 kind: hir::TraitItemKind::Const(ty, Some(body_id)),
80 }) => (*body_id, ty.span, None),
81 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
82 (*body, tcx.hir().span(*hir_id), None)
85 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def.did),
88 // If we don't have a specialized span for the body, just use the
90 let span_with_body = span_with_body.unwrap_or_else(|| tcx.hir().span(id));
91 let arena = Arena::default();
93 tcx.infer_ctxt().enter(|infcx| {
94 let body = if let Some(ErrorReported) = typeck_results.tainted_by_errors {
95 build::construct_error(&infcx, def, id, body_id, body_owner_kind)
96 } else if body_owner_kind.is_fn_or_closure() {
97 // fetch the fully liberated fn signature (that is, all bound
98 // types/lifetimes replaced)
99 let fn_sig = typeck_results.liberated_fn_sigs()[id];
100 let fn_def_id = tcx.hir().local_def_id(id);
102 let safety = match fn_sig.unsafety {
103 hir::Unsafety::Normal => Safety::Safe,
104 hir::Unsafety::Unsafe => Safety::FnUnsafe,
107 let body = tcx.hir().body(body_id);
108 let thir = build_thir(tcx, def, &arena, &body.value);
109 let ty = tcx.type_of(fn_def_id);
110 let mut abi = fn_sig.abi;
111 let implicit_argument = match ty.kind() {
113 // HACK(eddyb) Avoid having RustCall on closures,
114 // as it adds unnecessary (and wrong) auto-tupling.
116 vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)]
118 ty::Generator(..) => {
119 let gen_ty = tcx.typeck_body(body_id).node_type(id);
121 // The resume argument may be missing, in that case we need to provide it here.
122 // It will always be `()` in this case.
123 if body.params.is_empty() {
125 ArgInfo(gen_ty, None, None, None),
126 ArgInfo(tcx.mk_unit(), None, None, None),
129 vec![ArgInfo(gen_ty, None, None, None)]
135 let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| {
136 let owner_id = tcx.hir().body_owner(body_id);
139 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
140 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
141 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
142 match fn_decl.implicit_self {
143 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
144 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
145 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
146 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
157 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
158 // (as it's created inside the body itself, not passed in from outside).
159 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
160 let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(arg.span));
162 tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()])
164 fn_sig.inputs()[index]
167 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
170 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
172 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
173 let gen_ty = tcx.typeck_body(body_id).node_type(id);
174 let gen_sig = match gen_ty.kind() {
175 ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(),
176 _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty),
178 (Some(gen_sig.yield_ty), gen_sig.return_ty)
180 (None, fn_sig.output())
183 let mut mir = build::construct_fn(
196 if yield_ty.is_some() {
197 mir.generator.as_mut().unwrap().yield_ty = yield_ty;
201 // Get the revealed type of this const. This is *not* the adjusted
202 // type of its body, which may be a subtype of this type. For
206 // static X: fn(&'static ()) = foo;
208 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
209 // is not the same as the type of X. We need the type of the return
210 // place to be the type of the constant because NLL typeck will
213 let return_ty = typeck_results.node_type(id);
215 let ast_expr = &tcx.hir().body(body_id).value;
216 let thir = build_thir(tcx, def, &arena, ast_expr);
218 build::construct_const(&infcx, thir, def, id, return_ty, return_ty_span)
221 lints::check(tcx, &body);
223 // The borrow checker will replace all the regions here with its own
224 // inference variables. There's no point having non-erased regions here.
225 // The exception is `body.user_type_annotations`, which is used unmodified
226 // by borrow checking.
228 !(body.local_decls.has_free_regions()
229 || body.basic_blocks().has_free_regions()
230 || body.var_debug_info.has_free_regions()
231 || body.yield_ty().has_free_regions()),
232 "Unexpected free regions in MIR: {:?}",
240 ///////////////////////////////////////////////////////////////////////////
241 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
243 fn liberated_closure_env_ty(
245 closure_expr_id: hir::HirId,
246 body_id: hir::BodyId,
248 let closure_ty = tcx.typeck_body(body_id).node_type(closure_expr_id);
250 let (closure_def_id, closure_substs) = match *closure_ty.kind() {
251 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
252 _ => bug!("closure expr does not have closure type: {:?}", closure_ty),
255 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
256 tcx.erase_late_bound_regions(closure_env_ty)
259 #[derive(Debug, PartialEq, Eq)]
261 /// Evaluation is currently within a statement.
263 /// Examples include:
265 /// 2. `let _ = EXPR;`
266 /// 3. `let x = EXPR;`
268 /// If true, then statement discards result from evaluating
269 /// the expression (such as examples 1 and 2 above).
270 ignores_expr_result: bool,
273 /// Evaluation is currently within the tail expression of a block.
275 /// Example: `{ STMT_1; STMT_2; EXPR }`
277 /// If true, then the surrounding context of the block ignores
278 /// the result of evaluating the block's tail expression.
280 /// Example: `let _ = { STMT_1; EXPR };`
281 tail_result_is_ignored: bool,
283 /// `Span` of the tail expression.
287 /// Generic mark meaning that the block occurred as a subexpression
288 /// where the result might be used.
290 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
295 fn is_tail_expr(&self) -> bool {
297 BlockFrame::TailExpr { .. } => true,
299 BlockFrame::Statement { .. } | BlockFrame::SubExpr => false,
302 fn is_statement(&self) -> bool {
304 BlockFrame::Statement { .. } => true,
306 BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false,
312 struct BlockContext(Vec<BlockFrame>);
314 struct Builder<'a, 'tcx> {
316 infcx: &'a InferCtxt<'a, 'tcx>,
317 typeck_results: &'tcx TypeckResults<'tcx>,
318 region_scope_tree: &'tcx region::ScopeTree,
319 param_env: ty::ParamEnv<'tcx>,
325 check_overflow: bool,
328 generator_kind: Option<GeneratorKind>,
330 /// The current set of scopes, updated as we traverse;
331 /// see the `scope` module for more details.
332 scopes: scope::Scopes<'tcx>,
334 /// The block-context: each time we build the code within an thir::Block,
335 /// we push a frame here tracking whether we are building a statement or
336 /// if we are pushing the tail expression of the block. This is used to
337 /// embed information in generated temps about whether they were created
338 /// for a block tail expression or not.
340 /// It would be great if we could fold this into `self.scopes`
341 /// somehow, but right now I think that is very tightly tied to
342 /// the code generation in ways that we cannot (or should not)
343 /// start just throwing new entries onto that vector in order to
344 /// distinguish the context of EXPR1 from the context of EXPR2 in
345 /// `{ STMTS; EXPR1 } + EXPR2`.
346 block_context: BlockContext,
348 /// The current unsafe block in scope, even if it is hidden by
349 /// a `PushUnsafeBlock`.
350 unpushed_unsafe: Safety,
352 /// The number of `push_unsafe_block` levels in scope.
353 push_unsafe_count: usize,
355 /// The vector of all scopes that we have created thus far;
356 /// we track this for debuginfo later.
357 source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
358 source_scope: SourceScope,
360 /// The guard-context: each time we build the guard expression for
361 /// a match arm, we push onto this stack, and then pop when we
362 /// finish building it.
363 guard_context: Vec<GuardFrame>,
365 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
366 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
367 var_indices: HirIdMap<LocalsForNode>,
368 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
369 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
370 upvar_mutbls: Vec<Mutability>,
371 unit_temp: Option<Place<'tcx>>,
373 var_debug_info: Vec<VarDebugInfo<'tcx>>,
376 impl<'a, 'tcx> Builder<'a, 'tcx> {
377 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
378 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
381 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
382 self.var_indices[&id].local_id(for_guard)
390 fn push(&mut self, bf: BlockFrame) {
393 fn pop(&mut self) -> Option<BlockFrame> {
397 /// Traverses the frames on the `BlockContext`, searching for either
398 /// the first block-tail expression frame with no intervening
401 /// Notably, this skips over `SubExpr` frames; this method is
402 /// meant to be used in the context of understanding the
403 /// relationship of a temp (created within some complicated
404 /// expression) with its containing expression, and whether the
405 /// value of that *containing expression* (not the temp!) is
407 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
408 for bf in self.0.iter().rev() {
410 BlockFrame::SubExpr => continue,
411 BlockFrame::Statement { .. } => break,
412 &BlockFrame::TailExpr { tail_result_is_ignored, span } => {
413 return Some(BlockTailInfo { tail_result_is_ignored, span });
421 /// Looks at the topmost frame on the BlockContext and reports
422 /// whether its one that would discard a block tail result.
424 /// Unlike `currently_within_ignored_tail_expression`, this does
425 /// *not* skip over `SubExpr` frames: here, we want to know
426 /// whether the block result itself is discarded.
427 fn currently_ignores_tail_results(&self) -> bool {
428 match self.0.last() {
429 // no context: conservatively assume result is read
432 // sub-expression: block result feeds into some computation
433 Some(BlockFrame::SubExpr) => false,
435 // otherwise: use accumulated is_ignored state.
437 BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. }
438 | BlockFrame::Statement { ignores_expr_result: ignored },
446 /// In the usual case, a `HirId` for an identifier maps to at most
447 /// one `Local` declaration.
450 /// The exceptional case is identifiers in a match arm's pattern
451 /// that are referenced in a guard of that match arm. For these,
452 /// we have `2` Locals.
454 /// * `for_arm_body` is the Local used in the arm body (which is
455 /// just like the `One` case above),
457 /// * `ref_for_guard` is the Local used in the arm's guard (which
458 /// is a reference to a temp that is an alias of
460 ForGuard { ref_for_guard: Local, for_arm_body: Local },
464 struct GuardFrameLocal {
468 impl GuardFrameLocal {
469 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
470 GuardFrameLocal { id }
476 /// These are the id's of names that are bound by patterns of the
477 /// arm of *this* guard.
479 /// (Frames higher up the stack will have the id's bound in arms
480 /// further out, such as in a case like:
483 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
486 /// here, when building for FIXME.
487 locals: Vec<GuardFrameLocal>,
490 /// `ForGuard` indicates whether we are talking about:
491 /// 1. The variable for use outside of guard expressions, or
492 /// 2. The temp that holds reference to (1.), which is actually what the
493 /// guard expressions see.
494 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
501 fn local_id(&self, for_guard: ForGuard) -> Local {
502 match (self, for_guard) {
503 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard)
505 &LocalsForNode::ForGuard { ref_for_guard: local_id, .. },
506 ForGuard::RefWithinGuard,
508 | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => {
512 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => {
513 bug!("anything with one local should never be within a guard.")
520 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
523 rustc_index::newtype_index! {
524 struct ScopeId { .. }
527 ///////////////////////////////////////////////////////////////////////////
528 /// The `BlockAnd` "monad" packages up the new basic block along with a
529 /// produced value (sometimes just unit, of course). The `unpack!`
530 /// macro (and methods below) makes working with `BlockAnd` much more
533 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
534 struct BlockAnd<T>(BasicBlock, T);
536 trait BlockAndExtension {
537 fn and<T>(self, v: T) -> BlockAnd<T>;
538 fn unit(self) -> BlockAnd<()>;
541 impl BlockAndExtension for BasicBlock {
542 fn and<T>(self, v: T) -> BlockAnd<T> {
546 fn unit(self) -> BlockAnd<()> {
551 /// Update a block pointer and return the value.
552 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
553 macro_rules! unpack {
554 ($x:ident = $c:expr) => {{
555 let BlockAnd(b, v) = $c;
561 let BlockAnd(b, ()) = $c;
566 fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: LocalDefId, _abi: Abi) -> bool {
567 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy.
568 let attrs = &tcx.get_attrs(fn_def_id.to_def_id());
569 let unwind_attr = attr::find_unwind_attr(&tcx.sess, attrs);
571 // We never unwind, so it's not relevant to stop an unwind.
572 if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
576 // This is a special case: some functions have a C abi but are meant to
577 // unwind anyway. Don't stop them.
579 None => false, // FIXME(#58794); should be `!(abi == Abi::Rust || abi == Abi::RustCall)`
580 Some(UnwindAttr::Allowed) => false,
581 Some(UnwindAttr::Aborts) => true,
585 ///////////////////////////////////////////////////////////////////////////
586 /// the main entry point for building MIR for a function
588 struct ArgInfo<'tcx>(
591 Option<&'tcx hir::Param<'tcx>>,
592 Option<ImplicitSelfKind>,
595 fn construct_fn<'tcx, A>(
596 infcx: &InferCtxt<'_, 'tcx>,
597 fn_def: ty::WithOptConstParam<LocalDefId>,
603 return_ty_span: Span,
604 body: &'tcx hir::Body<'tcx>,
605 expr: &Expr<'_, 'tcx>,
606 span_with_body: Span,
609 A: Iterator<Item = ArgInfo<'tcx>>,
611 let arguments: Vec<_> = arguments.collect();
614 let span = tcx.hir().span(fn_id);
616 let mut builder = Builder::new(
628 let call_site_scope =
629 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite };
631 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments };
632 let source_info = builder.source_info(span);
633 let call_site_s = (call_site_scope, source_info);
634 unpack!(builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
635 let arg_scope_s = (arg_scope, source_info);
636 // Attribute epilogue to function's closing brace
637 let fn_end = span_with_body.shrink_to_hi();
639 unpack!(builder.in_breakable_scope(None, Place::return_place(), fn_end, |builder| {
640 Some(builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
641 builder.args_and_body(
643 fn_def.did.to_def_id(),
650 let source_info = builder.source_info(fn_end);
651 builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
652 let should_abort = should_abort_on_panic(tcx, fn_def.did, abi);
653 builder.build_drop_trees(should_abort);
657 let spread_arg = if abi == Abi::RustCall {
658 // RustCall pseudo-ABI untuples the last argument.
659 Some(Local::new(arguments.len()))
663 debug!("fn_id {:?} has attrs {:?}", fn_def, tcx.get_attrs(fn_def.did.to_def_id()));
665 let mut body = builder.finish();
666 body.spread_arg = spread_arg;
670 fn construct_const<'a, 'tcx>(
671 infcx: &'a InferCtxt<'a, 'tcx>,
672 expr: &Expr<'_, 'tcx>,
673 def: ty::WithOptConstParam<LocalDefId>,
679 let span = tcx.hir().span(hir_id);
681 Builder::new(infcx, def, hir_id, span, 0, Safety::Safe, const_ty, const_ty_span, None);
683 let mut block = START_BLOCK;
684 unpack!(block = builder.expr_into_dest(Place::return_place(), block, &expr));
686 let source_info = builder.source_info(span);
687 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
689 builder.build_drop_trees(false);
694 /// Construct MIR for a item that has had errors in type checking.
696 /// This is required because we may still want to run MIR passes on an item
697 /// with type errors, but normal MIR construction can't handle that in general.
698 fn construct_error<'a, 'tcx>(
699 infcx: &'a InferCtxt<'a, 'tcx>,
700 def: ty::WithOptConstParam<LocalDefId>,
702 body_id: hir::BodyId,
703 body_owner_kind: hir::BodyOwnerKind,
706 let span = tcx.hir().span(hir_id);
707 let ty = tcx.ty_error();
708 let generator_kind = tcx.hir().body(body_id).generator_kind;
709 let num_params = match body_owner_kind {
710 hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len(),
711 hir::BodyOwnerKind::Closure => {
712 if generator_kind.is_some() {
713 // Generators have an implicit `self` parameter *and* a possibly
714 // implicit resume parameter.
717 // The implicit self parameter adds another local in MIR.
718 1 + tcx.hir().fn_decl_by_hir_id(hir_id).unwrap().inputs.len()
721 hir::BodyOwnerKind::Const => 0,
722 hir::BodyOwnerKind::Static(_) => 0,
725 Builder::new(infcx, def, hir_id, span, num_params, Safety::Safe, ty, span, generator_kind);
726 let source_info = builder.source_info(span);
727 // Some MIR passes will expect the number of parameters to match the
728 // function declaration.
729 for _ in 0..num_params {
730 builder.local_decls.push(LocalDecl::with_source_info(ty, source_info));
732 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
733 let mut body = builder.finish();
734 body.generator.as_mut().map(|gen| gen.yield_ty = Some(ty));
738 impl<'a, 'tcx> Builder<'a, 'tcx> {
740 infcx: &'a InferCtxt<'a, 'tcx>,
741 def: ty::WithOptConstParam<LocalDefId>,
748 generator_kind: Option<GeneratorKind>,
749 ) -> Builder<'a, 'tcx> {
751 let attrs = tcx.hir().attrs(hir_id);
752 // Some functions always have overflow checks enabled,
753 // however, they may not get codegen'd, depending on
754 // the settings for the crate they are codegened in.
755 let mut check_overflow = tcx.sess.contains_name(attrs, sym::rustc_inherit_overflow_checks);
756 // Respect -C overflow-checks.
757 check_overflow |= tcx.sess.overflow_checks();
758 // Constants always need overflow checks.
759 check_overflow |= matches!(
760 tcx.hir().body_owner_kind(hir_id),
761 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_)
764 let lint_level = LintLevel::Explicit(hir_id);
765 let mut builder = Builder {
768 typeck_results: tcx.typeck_opt_const_arg(def),
769 region_scope_tree: tcx.region_scope_tree(def.did),
770 param_env: tcx.param_env(def.did),
771 def_id: def.did.to_def_id(),
774 cfg: CFG { basic_blocks: IndexVec::new() },
778 scopes: scope::Scopes::new(),
779 block_context: BlockContext::new(),
780 source_scopes: IndexVec::new(),
781 source_scope: OUTERMOST_SOURCE_SCOPE,
782 guard_context: vec![],
783 push_unsafe_count: 0,
784 unpushed_unsafe: safety,
785 local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1),
786 canonical_user_type_annotations: IndexVec::new(),
787 upvar_mutbls: vec![],
788 var_indices: Default::default(),
790 var_debug_info: vec![],
793 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
795 builder.new_source_scope(span, lint_level, Some(safety)),
796 OUTERMOST_SOURCE_SCOPE
798 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
803 fn finish(self) -> Body<'tcx> {
804 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
805 if block.terminator.is_none() {
806 span_bug!(self.fn_span, "no terminator on block {:?}", index);
811 MirSource::item(self.def_id),
812 self.cfg.basic_blocks,
815 self.canonical_user_type_annotations,
825 mut block: BasicBlock,
827 arguments: &[ArgInfo<'tcx>],
828 argument_scope: region::Scope,
829 expr: &Expr<'_, 'tcx>,
831 // Allocate locals for the function arguments
832 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
834 SourceInfo::outermost(arg_opt.map_or(self.fn_span, |arg| arg.pat.span));
835 let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info));
837 // If this is a simple binding pattern, give debuginfo a nice name.
838 if let Some(arg) = arg_opt {
839 if let Some(ident) = arg.pat.simple_ident() {
840 self.var_debug_info.push(VarDebugInfo {
843 value: VarDebugInfoContents::Place(arg_local.into()),
850 let tcx_hir = tcx.hir();
851 let hir_typeck_results = self.typeck_results;
853 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
854 // indexed closure and we stored in a map called closure_captures in TypeckResults
855 // with the closure's DefId. Here, we run through that vec of UpvarIds for
856 // the given closure and use the necessary information to create upvar
857 // debuginfo and to fill `self.upvar_mutbls`.
858 if hir_typeck_results.closure_min_captures.get(&fn_def_id).is_some() {
859 let closure_env_arg = Local::new(1);
860 let mut closure_env_projs = vec![];
861 let mut closure_ty = self.local_decls[closure_env_arg].ty;
862 if let ty::Ref(_, ty, _) = closure_ty.kind() {
863 closure_env_projs.push(ProjectionElem::Deref);
866 let upvar_substs = match closure_ty.kind() {
867 ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
868 ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
869 _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
871 let capture_tys = upvar_substs.upvar_tys();
872 let captures_with_tys =
873 hir_typeck_results.closure_min_captures_flattened(fn_def_id).zip(capture_tys);
875 self.upvar_mutbls = captures_with_tys
877 .map(|(i, (captured_place, ty))| {
878 let capture = captured_place.info.capture_kind;
879 let var_id = match captured_place.place.base {
880 HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
881 _ => bug!("Expected an upvar"),
884 let mutability = captured_place.mutability;
886 // FIXME(project-rfc-2229#8): Store more precise information
887 let mut name = kw::Empty;
888 if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) {
889 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
894 let mut projs = closure_env_projs.clone();
895 projs.push(ProjectionElem::Field(Field::new(i), ty));
897 ty::UpvarCapture::ByValue(_) => {}
898 ty::UpvarCapture::ByRef(..) => {
899 projs.push(ProjectionElem::Deref);
903 self.var_debug_info.push(VarDebugInfo {
905 source_info: SourceInfo::outermost(tcx_hir.span(var_id)),
906 value: VarDebugInfoContents::Place(Place {
907 local: closure_env_arg,
908 projection: tcx.intern_place_elems(&projs),
917 let mut scope = None;
918 // Bind the argument patterns
919 for (index, arg_info) in arguments.iter().enumerate() {
920 // Function arguments always get the first Local indices after the return place
921 let local = Local::new(index + 1);
922 let place = Place::from(local);
923 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
925 // Make sure we drop (parts of) the argument even when not matched on.
927 arg_opt.as_ref().map_or(expr.span, |arg| arg.pat.span),
933 if let Some(arg) = arg_opt {
934 let pat = match tcx.hir().get(arg.pat.hir_id) {
935 Node::Pat(pat) | Node::Binding(pat) => pat,
936 node => bug!("pattern became {:?}", node),
938 let pattern = Pat::from_hir(tcx, self.param_env, self.typeck_results, pat);
939 let original_source_scope = self.source_scope;
940 let span = pattern.span;
941 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
942 match *pattern.kind {
943 // Don't introduce extra copies for simple bindings
947 mode: BindingMode::ByValue,
951 self.local_decls[local].mutability = mutability;
952 self.local_decls[local].source_info.scope = self.source_scope;
953 self.local_decls[local].local_info = if let Some(kind) = self_binding {
954 Some(box LocalInfo::User(ClearCrossCrate::Set(
955 BindingForm::ImplicitSelf(*kind),
958 let binding_mode = ty::BindingMode::BindByValue(mutability);
959 Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
963 opt_match_place: Some((Some(place), span)),
968 self.var_indices.insert(var, LocalsForNode::One(local));
971 scope = self.declare_bindings(
975 matches::ArmHasGuard(false),
976 Some((Some(&place), span)),
978 unpack!(block = self.place_into_pattern(block, pattern, place, false));
981 self.source_scope = original_source_scope;
985 // Enter the argument pattern bindings source scope, if it exists.
986 if let Some(source_scope) = scope {
987 self.source_scope = source_scope;
990 self.expr_into_dest(Place::return_place(), block, &expr)
993 fn set_correct_source_scope_for_arg(
995 arg_hir_id: hir::HirId,
996 original_source_scope: SourceScope,
1000 let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir_id);
1001 let parent_root = tcx.maybe_lint_level_root_bounded(
1002 self.source_scopes[original_source_scope]
1005 .assert_crate_local()
1009 if current_root != parent_root {
1011 self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
1015 fn get_unit_temp(&mut self) -> Place<'tcx> {
1016 match self.unit_temp {
1019 let ty = self.tcx.mk_unit();
1020 let fn_span = self.fn_span;
1021 let tmp = self.temp(ty, fn_span);
1022 self.unit_temp = Some(tmp);
1029 ///////////////////////////////////////////////////////////////////////////
1030 // Builder methods are broken up into modules, depending on what kind
1031 // of thing is being lowered. Note that they use the `unpack` macro
1032 // above extensively.