2 use crate::build::scope::DropKind;
3 use crate::thir::cx::Cx;
4 use crate::thir::{BindingMode, LintLevel, 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;
10 use rustc_hir::{GeneratorKind, HirIdMap, Node};
11 use rustc_index::vec::{Idx, IndexVec};
12 use rustc_infer::infer::TyCtxtInferExt;
13 use rustc_middle::middle::region;
14 use rustc_middle::mir::*;
15 use rustc_middle::ty::subst::Subst;
16 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
17 use rustc_span::symbol::kw;
19 use rustc_target::spec::abi::Abi;
20 use rustc_target::spec::PanicStrategy;
24 crate fn mir_built<'tcx>(
26 def: ty::WithOptConstParam<LocalDefId>,
27 ) -> &'tcx ty::steal::Steal<Body<'tcx>> {
28 if let Some(def) = def.try_upgrade(tcx) {
29 return tcx.mir_built(def);
32 tcx.alloc_steal_mir(mir_build(tcx, def))
35 /// Construct the MIR for a given `DefId`.
36 fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
37 let id = tcx.hir().as_local_hir_id(def.did);
39 // Figure out what primary body this item has.
40 let (body_id, return_ty_span) = match tcx.hir().get(id) {
41 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. }) => {
42 (*body_id, decl.output.span())
44 Node::Item(hir::Item {
45 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
48 | Node::ImplItem(hir::ImplItem {
49 kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id),
52 | Node::TraitItem(hir::TraitItem {
53 kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)),
55 }) => (*body_id, decl.output.span()),
56 Node::Item(hir::Item {
57 kind: hir::ItemKind::Static(ty, _, body_id) | hir::ItemKind::Const(ty, body_id),
60 | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. })
61 | Node::TraitItem(hir::TraitItem {
62 kind: hir::TraitItemKind::Const(ty, Some(body_id)),
64 }) => (*body_id, ty.span),
65 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => (*body, tcx.hir().span(*hir_id)),
67 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def.did),
70 tcx.infer_ctxt().enter(|infcx| {
71 let cx = Cx::new(&infcx, def, id);
72 let body = if let Some(ErrorReported) = cx.typeck_results().tainted_by_errors {
73 build::construct_error(cx, body_id)
74 } else if cx.body_owner_kind.is_fn_or_closure() {
75 // fetch the fully liberated fn signature (that is, all bound
76 // types/lifetimes replaced)
77 let fn_sig = cx.typeck_results().liberated_fn_sigs()[id];
78 let fn_def_id = tcx.hir().local_def_id(id);
80 let safety = match fn_sig.unsafety {
81 hir::Unsafety::Normal => Safety::Safe,
82 hir::Unsafety::Unsafe => Safety::FnUnsafe,
85 let body = tcx.hir().body(body_id);
86 let ty = tcx.type_of(fn_def_id);
87 let mut abi = fn_sig.abi;
88 let implicit_argument = match ty.kind {
90 // HACK(eddyb) Avoid having RustCall on closures,
91 // as it adds unnecessary (and wrong) auto-tupling.
93 vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)]
95 ty::Generator(..) => {
96 let gen_ty = tcx.typeck_body(body_id).node_type(id);
98 // The resume argument may be missing, in that case we need to provide it here.
99 // It will always be `()` in this case.
100 if body.params.is_empty() {
102 ArgInfo(gen_ty, None, None, None),
103 ArgInfo(tcx.mk_unit(), None, None, None),
106 vec![ArgInfo(gen_ty, None, None, None)]
112 let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| {
113 let owner_id = tcx.hir().body_owner(body_id);
116 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
117 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
118 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
119 match fn_decl.implicit_self {
120 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
121 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
122 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
123 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
134 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
135 // (as it's created inside the body itself, not passed in from outside).
136 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
138 tcx.require_lang_item(lang_items::VaListTypeLangItem, Some(arg.span));
140 tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()])
142 fn_sig.inputs()[index]
145 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
148 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
150 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
151 let gen_ty = tcx.typeck_body(body_id).node_type(id);
152 let gen_sig = match gen_ty.kind {
153 ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(),
154 _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty),
156 (Some(gen_sig.yield_ty), gen_sig.return_ty)
158 (None, fn_sig.output())
161 let mut mir = build::construct_fn(
171 mir.yield_ty = yield_ty;
174 // Get the revealed type of this const. This is *not* the adjusted
175 // type of its body, which may be a subtype of this type. For
179 // static X: fn(&'static ()) = foo;
181 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
182 // is not the same as the type of X. We need the type of the return
183 // place to be the type of the constant because NLL typeck will
186 let return_ty = cx.typeck_results().node_type(id);
188 build::construct_const(cx, body_id, return_ty, return_ty_span)
191 lints::check(tcx, &body, def.did);
193 // The borrow checker will replace all the regions here with its own
194 // inference variables. There's no point having non-erased regions here.
195 // The exception is `body.user_type_annotations`, which is used unmodified
196 // by borrow checking.
198 !(body.local_decls.has_free_regions()
199 || body.basic_blocks().has_free_regions()
200 || body.var_debug_info.has_free_regions()
201 || body.yield_ty.has_free_regions()),
202 "Unexpected free regions in MIR: {:?}",
210 ///////////////////////////////////////////////////////////////////////////
211 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
213 fn liberated_closure_env_ty(
215 closure_expr_id: hir::HirId,
216 body_id: hir::BodyId,
218 let closure_ty = tcx.typeck_body(body_id).node_type(closure_expr_id);
220 let (closure_def_id, closure_substs) = match closure_ty.kind {
221 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
222 _ => bug!("closure expr does not have closure type: {:?}", closure_ty),
225 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
226 tcx.erase_late_bound_regions(&closure_env_ty)
229 #[derive(Debug, PartialEq, Eq)]
231 /// Evaluation is currently within a statement.
233 /// Examples include:
235 /// 2. `let _ = EXPR;`
236 /// 3. `let x = EXPR;`
238 /// If true, then statement discards result from evaluating
239 /// the expression (such as examples 1 and 2 above).
240 ignores_expr_result: bool,
243 /// Evaluation is currently within the tail expression of a block.
245 /// Example: `{ STMT_1; STMT_2; EXPR }`
247 /// If true, then the surrounding context of the block ignores
248 /// the result of evaluating the block's tail expression.
250 /// Example: `let _ = { STMT_1; EXPR };`
251 tail_result_is_ignored: bool,
253 /// `Span` of the tail expression.
257 /// Generic mark meaning that the block occurred as a subexpression
258 /// where the result might be used.
260 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
265 fn is_tail_expr(&self) -> bool {
267 BlockFrame::TailExpr { .. } => true,
269 BlockFrame::Statement { .. } | BlockFrame::SubExpr => false,
272 fn is_statement(&self) -> bool {
274 BlockFrame::Statement { .. } => true,
276 BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false,
282 struct BlockContext(Vec<BlockFrame>);
284 struct Builder<'a, 'tcx> {
290 generator_kind: Option<GeneratorKind>,
292 /// The current set of scopes, updated as we traverse;
293 /// see the `scope` module for more details.
294 scopes: scope::Scopes<'tcx>,
296 /// The block-context: each time we build the code within an thir::Block,
297 /// we push a frame here tracking whether we are building a statement or
298 /// if we are pushing the tail expression of the block. This is used to
299 /// embed information in generated temps about whether they were created
300 /// for a block tail expression or not.
302 /// It would be great if we could fold this into `self.scopes`
303 /// somehow, but right now I think that is very tightly tied to
304 /// the code generation in ways that we cannot (or should not)
305 /// start just throwing new entries onto that vector in order to
306 /// distinguish the context of EXPR1 from the context of EXPR2 in
307 /// `{ STMTS; EXPR1 } + EXPR2`.
308 block_context: BlockContext,
310 /// The current unsafe block in scope, even if it is hidden by
311 /// a `PushUnsafeBlock`.
312 unpushed_unsafe: Safety,
314 /// The number of `push_unsafe_block` levels in scope.
315 push_unsafe_count: usize,
317 /// The vector of all scopes that we have created thus far;
318 /// we track this for debuginfo later.
319 source_scopes: IndexVec<SourceScope, SourceScopeData>,
320 source_scope: SourceScope,
322 /// The guard-context: each time we build the guard expression for
323 /// a match arm, we push onto this stack, and then pop when we
324 /// finish building it.
325 guard_context: Vec<GuardFrame>,
327 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
328 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
329 var_indices: HirIdMap<LocalsForNode>,
330 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
331 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
332 upvar_mutbls: Vec<Mutability>,
333 unit_temp: Option<Place<'tcx>>,
335 var_debug_info: Vec<VarDebugInfo<'tcx>>,
337 /// Cached block with the `RESUME` terminator; this is created
338 /// when first set of cleanups are built.
339 cached_resume_block: Option<BasicBlock>,
340 /// Cached block with the `RETURN` terminator.
341 cached_return_block: Option<BasicBlock>,
342 /// Cached block with the `UNREACHABLE` terminator.
343 cached_unreachable_block: Option<BasicBlock>,
346 impl<'a, 'tcx> Builder<'a, 'tcx> {
347 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
348 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
351 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
352 self.var_indices[&id].local_id(for_guard)
360 fn push(&mut self, bf: BlockFrame) {
363 fn pop(&mut self) -> Option<BlockFrame> {
367 /// Traverses the frames on the `BlockContext`, searching for either
368 /// the first block-tail expression frame with no intervening
371 /// Notably, this skips over `SubExpr` frames; this method is
372 /// meant to be used in the context of understanding the
373 /// relationship of a temp (created within some complicated
374 /// expression) with its containing expression, and whether the
375 /// value of that *containing expression* (not the temp!) is
377 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
378 for bf in self.0.iter().rev() {
380 BlockFrame::SubExpr => continue,
381 BlockFrame::Statement { .. } => break,
382 &BlockFrame::TailExpr { tail_result_is_ignored, span } => {
383 return Some(BlockTailInfo { tail_result_is_ignored, span });
391 /// Looks at the topmost frame on the BlockContext and reports
392 /// whether its one that would discard a block tail result.
394 /// Unlike `currently_within_ignored_tail_expression`, this does
395 /// *not* skip over `SubExpr` frames: here, we want to know
396 /// whether the block result itself is discarded.
397 fn currently_ignores_tail_results(&self) -> bool {
398 match self.0.last() {
399 // no context: conservatively assume result is read
402 // sub-expression: block result feeds into some computation
403 Some(BlockFrame::SubExpr) => false,
405 // otherwise: use accumulated is_ignored state.
407 BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. }
408 | BlockFrame::Statement { ignores_expr_result: ignored },
416 /// In the usual case, a `HirId` for an identifier maps to at most
417 /// one `Local` declaration.
420 /// The exceptional case is identifiers in a match arm's pattern
421 /// that are referenced in a guard of that match arm. For these,
422 /// we have `2` Locals.
424 /// * `for_arm_body` is the Local used in the arm body (which is
425 /// just like the `One` case above),
427 /// * `ref_for_guard` is the Local used in the arm's guard (which
428 /// is a reference to a temp that is an alias of
430 ForGuard { ref_for_guard: Local, for_arm_body: Local },
434 struct GuardFrameLocal {
438 impl GuardFrameLocal {
439 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
440 GuardFrameLocal { id }
446 /// These are the id's of names that are bound by patterns of the
447 /// arm of *this* guard.
449 /// (Frames higher up the stack will have the id's bound in arms
450 /// further out, such as in a case like:
453 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
456 /// here, when building for FIXME.
457 locals: Vec<GuardFrameLocal>,
460 /// `ForGuard` indicates whether we are talking about:
461 /// 1. The variable for use outside of guard expressions, or
462 /// 2. The temp that holds reference to (1.), which is actually what the
463 /// guard expressions see.
464 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
471 fn local_id(&self, for_guard: ForGuard) -> Local {
472 match (self, for_guard) {
473 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard)
475 &LocalsForNode::ForGuard { ref_for_guard: local_id, .. },
476 ForGuard::RefWithinGuard,
478 | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => {
482 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => {
483 bug!("anything with one local should never be within a guard.")
490 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
493 rustc_index::newtype_index! {
494 struct ScopeId { .. }
497 ///////////////////////////////////////////////////////////////////////////
498 /// The `BlockAnd` "monad" packages up the new basic block along with a
499 /// produced value (sometimes just unit, of course). The `unpack!`
500 /// macro (and methods below) makes working with `BlockAnd` much more
503 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
504 struct BlockAnd<T>(BasicBlock, T);
506 trait BlockAndExtension {
507 fn and<T>(self, v: T) -> BlockAnd<T>;
508 fn unit(self) -> BlockAnd<()>;
511 impl BlockAndExtension for BasicBlock {
512 fn and<T>(self, v: T) -> BlockAnd<T> {
516 fn unit(self) -> BlockAnd<()> {
521 /// Update a block pointer and return the value.
522 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
523 macro_rules! unpack {
524 ($x:ident = $c:expr) => {{
525 let BlockAnd(b, v) = $c;
531 let BlockAnd(b, ()) = $c;
536 fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: LocalDefId, _abi: Abi) -> bool {
537 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy.
538 let attrs = &tcx.get_attrs(fn_def_id.to_def_id());
539 let unwind_attr = attr::find_unwind_attr(&tcx.sess, attrs);
541 // We never unwind, so it's not relevant to stop an unwind.
542 if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
546 // This is a special case: some functions have a C abi but are meant to
547 // unwind anyway. Don't stop them.
549 None => false, // FIXME(#58794); should be `!(abi == Abi::Rust || abi == Abi::RustCall)`
550 Some(UnwindAttr::Allowed) => false,
551 Some(UnwindAttr::Aborts) => true,
555 ///////////////////////////////////////////////////////////////////////////
556 /// the main entry point for building MIR for a function
558 struct ArgInfo<'tcx>(
561 Option<&'tcx hir::Param<'tcx>>,
562 Option<ImplicitSelfKind>,
565 fn construct_fn<'a, 'tcx, A>(
572 return_ty_span: Span,
573 body: &'tcx hir::Body<'tcx>,
576 A: Iterator<Item = ArgInfo<'tcx>>,
578 let arguments: Vec<_> = arguments.collect();
581 let tcx_hir = tcx.hir();
582 let span = tcx_hir.span(fn_id);
584 let fn_def_id = tcx_hir.local_def_id(fn_id);
586 let mut builder = Builder::new(
596 let call_site_scope =
597 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite };
599 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments };
600 let mut block = START_BLOCK;
601 let source_info = builder.source_info(span);
602 let call_site_s = (call_site_scope, source_info);
604 block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
605 if should_abort_on_panic(tcx, fn_def_id, abi) {
606 builder.schedule_abort();
609 let arg_scope_s = (arg_scope, source_info);
610 // `return_block` is called when we evaluate a `return` expression, so
611 // we just use `START_BLOCK` here.
613 block = builder.in_breakable_scope(
616 Place::return_place(),
618 builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
619 builder.args_and_body(
621 fn_def_id.to_def_id(),
630 // Attribute epilogue to function's closing brace
631 let fn_end = span.shrink_to_hi();
632 let source_info = builder.source_info(fn_end);
633 let return_block = builder.return_block();
634 builder.cfg.goto(block, source_info, return_block);
635 builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
636 // Attribute any unreachable codepaths to the function's closing brace
637 if let Some(unreachable_block) = builder.cached_unreachable_block {
638 builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable);
643 assert_eq!(block, builder.return_block());
645 let spread_arg = if abi == Abi::RustCall {
646 // RustCall pseudo-ABI untuples the last argument.
647 Some(Local::new(arguments.len()))
651 debug!("fn_id {:?} has attrs {:?}", fn_def_id, tcx.get_attrs(fn_def_id.to_def_id()));
653 let mut body = builder.finish();
654 body.spread_arg = spread_arg;
658 fn construct_const<'a, 'tcx>(
660 body_id: hir::BodyId,
665 let owner_id = tcx.hir().body_owner(body_id);
666 let span = tcx.hir().span(owner_id);
667 let mut builder = Builder::new(hir, span, 0, Safety::Safe, const_ty, const_ty_span, None);
669 let mut block = START_BLOCK;
670 let ast_expr = &tcx.hir().body(body_id).value;
671 let expr = builder.hir.mirror(ast_expr);
672 unpack!(block = builder.into_expr(Place::return_place(), block, expr));
674 let source_info = builder.source_info(span);
675 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
677 // Constants can't `return` so a return block should not be created.
678 assert_eq!(builder.cached_return_block, None);
680 // Constants may be match expressions in which case an unreachable block may
681 // be created, so terminate it properly.
682 if let Some(unreachable_block) = builder.cached_unreachable_block {
683 builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable);
689 /// Construct MIR for a item that has had errors in type checking.
691 /// This is required because we may still want to run MIR passes on an item
692 /// with type errors, but normal MIR construction can't handle that in general.
693 fn construct_error<'a, 'tcx>(hir: Cx<'a, 'tcx>, body_id: hir::BodyId) -> Body<'tcx> {
695 let owner_id = tcx.hir().body_owner(body_id);
696 let span = tcx.hir().span(owner_id);
697 let ty = tcx.ty_error();
698 let num_params = match hir.body_owner_kind {
699 hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len(),
700 hir::BodyOwnerKind::Closure => {
701 if tcx.hir().body(body_id).generator_kind().is_some() {
702 // Generators have an implicit `self` parameter *and* a possibly
703 // implicit resume parameter.
706 // The implicit self parameter adds another local in MIR.
707 1 + tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len()
710 hir::BodyOwnerKind::Const => 0,
711 hir::BodyOwnerKind::Static(_) => 0,
713 let mut builder = Builder::new(hir, span, num_params, Safety::Safe, ty, span, None);
714 let source_info = builder.source_info(span);
715 // Some MIR passes will expect the number of parameters to match the
716 // function declaration.
717 for _ in 0..num_params {
718 builder.local_decls.push(LocalDecl::with_source_info(ty, source_info));
720 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
721 let mut body = builder.finish();
722 if tcx.hir().body(body_id).generator_kind.is_some() {
723 body.yield_ty = Some(ty);
728 impl<'a, 'tcx> Builder<'a, 'tcx> {
736 generator_kind: Option<GeneratorKind>,
737 ) -> Builder<'a, 'tcx> {
738 let lint_level = LintLevel::Explicit(hir.root_lint_level);
739 let mut builder = Builder {
741 cfg: CFG { basic_blocks: IndexVec::new() },
745 scopes: Default::default(),
746 block_context: BlockContext::new(),
747 source_scopes: IndexVec::new(),
748 source_scope: OUTERMOST_SOURCE_SCOPE,
749 guard_context: vec![],
750 push_unsafe_count: 0,
751 unpushed_unsafe: safety,
752 local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1),
753 canonical_user_type_annotations: IndexVec::new(),
754 upvar_mutbls: vec![],
755 var_indices: Default::default(),
757 var_debug_info: vec![],
758 cached_resume_block: None,
759 cached_return_block: None,
760 cached_unreachable_block: None,
763 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
765 builder.new_source_scope(span, lint_level, Some(safety)),
766 OUTERMOST_SOURCE_SCOPE
768 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
773 fn finish(self) -> Body<'tcx> {
774 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
775 if block.terminator.is_none() {
776 span_bug!(self.fn_span, "no terminator on block {:?}", index);
781 self.cfg.basic_blocks,
784 self.canonical_user_type_annotations,
794 mut block: BasicBlock,
796 arguments: &[ArgInfo<'tcx>],
797 argument_scope: region::Scope,
798 ast_body: &'tcx hir::Expr<'tcx>,
800 // Allocate locals for the function arguments
801 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
803 SourceInfo::outermost(arg_opt.map_or(self.fn_span, |arg| arg.pat.span));
804 let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info));
806 // If this is a simple binding pattern, give debuginfo a nice name.
807 if let Some(arg) = arg_opt {
808 if let Some(ident) = arg.pat.simple_ident() {
809 self.var_debug_info.push(VarDebugInfo {
812 place: arg_local.into(),
818 let tcx = self.hir.tcx();
819 let tcx_hir = tcx.hir();
820 let hir_typeck_results = self.hir.typeck_results();
822 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
823 // indexed closure and we stored in a map called closure_captures in TypeckResults
824 // with the closure's DefId. Here, we run through that vec of UpvarIds for
825 // the given closure and use the necessary information to create upvar
826 // debuginfo and to fill `self.upvar_mutbls`.
827 if let Some(upvars) = hir_typeck_results.closure_captures.get(&fn_def_id) {
828 let closure_env_arg = Local::new(1);
829 let mut closure_env_projs = vec![];
830 let mut closure_ty = self.local_decls[closure_env_arg].ty;
831 if let ty::Ref(_, ty, _) = closure_ty.kind {
832 closure_env_projs.push(ProjectionElem::Deref);
835 let upvar_substs = match closure_ty.kind {
836 ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
837 ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
838 _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
840 let upvar_tys = upvar_substs.upvar_tys();
841 let upvars_with_tys = upvars.iter().zip(upvar_tys);
842 self.upvar_mutbls = upvars_with_tys
844 .map(|(i, ((&var_id, &upvar_id), ty))| {
845 let capture = hir_typeck_results.upvar_capture(upvar_id);
847 let mut mutability = Mutability::Not;
848 let mut name = kw::Invalid;
849 if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) {
850 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
852 match hir_typeck_results
853 .extract_binding_mode(tcx.sess, pat.hir_id, pat.span)
855 Some(ty::BindByValue(hir::Mutability::Mut)) => {
856 mutability = Mutability::Mut;
858 Some(_) => mutability = Mutability::Not,
864 let mut projs = closure_env_projs.clone();
865 projs.push(ProjectionElem::Field(Field::new(i), ty));
867 ty::UpvarCapture::ByValue => {}
868 ty::UpvarCapture::ByRef(..) => {
869 projs.push(ProjectionElem::Deref);
873 self.var_debug_info.push(VarDebugInfo {
875 source_info: SourceInfo::outermost(tcx_hir.span(var_id)),
877 local: closure_env_arg,
878 projection: tcx.intern_place_elems(&projs),
887 let mut scope = None;
888 // Bind the argument patterns
889 for (index, arg_info) in arguments.iter().enumerate() {
890 // Function arguments always get the first Local indices after the return place
891 let local = Local::new(index + 1);
892 let place = Place::from(local);
893 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
895 // Make sure we drop (parts of) the argument even when not matched on.
897 arg_opt.as_ref().map_or(ast_body.span, |arg| arg.pat.span),
903 if let Some(arg) = arg_opt {
904 let pattern = self.hir.pattern_from_hir(&arg.pat);
905 let original_source_scope = self.source_scope;
906 let span = pattern.span;
907 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
908 match *pattern.kind {
909 // Don't introduce extra copies for simple bindings
913 mode: BindingMode::ByValue,
917 self.local_decls[local].mutability = mutability;
918 self.local_decls[local].source_info.scope = self.source_scope;
919 self.local_decls[local].local_info = if let Some(kind) = self_binding {
920 Some(box LocalInfo::User(ClearCrossCrate::Set(
921 BindingForm::ImplicitSelf(*kind),
924 let binding_mode = ty::BindingMode::BindByValue(mutability);
925 Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
929 opt_match_place: Some((Some(place), span)),
934 self.var_indices.insert(var, LocalsForNode::One(local));
937 scope = self.declare_bindings(
941 matches::ArmHasGuard(false),
942 Some((Some(&place), span)),
944 unpack!(block = self.place_into_pattern(block, pattern, place, false));
947 self.source_scope = original_source_scope;
951 // Enter the argument pattern bindings source scope, if it exists.
952 if let Some(source_scope) = scope {
953 self.source_scope = source_scope;
956 let body = self.hir.mirror(ast_body);
957 self.into(Place::return_place(), block, body)
960 fn set_correct_source_scope_for_arg(
962 arg_hir_id: hir::HirId,
963 original_source_scope: SourceScope,
966 let tcx = self.hir.tcx();
967 let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir.root_lint_level);
968 let parent_root = tcx.maybe_lint_level_root_bounded(
969 self.source_scopes[original_source_scope]
972 .assert_crate_local()
974 self.hir.root_lint_level,
976 if current_root != parent_root {
978 self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
982 fn get_unit_temp(&mut self) -> Place<'tcx> {
983 match self.unit_temp {
986 let ty = self.hir.unit_ty();
987 let fn_span = self.fn_span;
988 let tmp = self.temp(ty, fn_span);
989 self.unit_temp = Some(tmp);
995 fn return_block(&mut self) -> BasicBlock {
996 match self.cached_return_block {
999 let rb = self.cfg.start_new_block();
1000 self.cached_return_block = Some(rb);
1007 ///////////////////////////////////////////////////////////////////////////
1008 // Builder methods are broken up into modules, depending on what kind
1009 // of thing is being lowered. Note that they use the `unpack` macro
1010 // above extensively.