2 use crate::build::scope::DropKind;
3 use crate::hair::cx::Cx;
4 use crate::hair::{BindingMode, LintLevel, PatKind};
5 use rustc_attr::{self as attr, UnwindAttr};
7 use rustc_hir::def_id::DefId;
8 use rustc_hir::lang_items;
9 use rustc_hir::{GeneratorKind, HirIdMap, Node};
10 use rustc_index::vec::{Idx, IndexVec};
11 use rustc_infer::infer::TyCtxtInferExt;
12 use rustc_middle::middle::region;
13 use rustc_middle::mir::*;
14 use rustc_middle::ty::subst::Subst;
15 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
16 use rustc_span::symbol::kw;
18 use rustc_target::spec::abi::Abi;
19 use rustc_target::spec::PanicStrategy;
23 crate fn mir_built(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::steal::Steal<BodyAndCache<'_>> {
24 tcx.alloc_steal_mir(mir_build(tcx, def_id))
27 /// Construct the MIR for a given `DefId`.
28 fn mir_build(tcx: TyCtxt<'_>, def_id: DefId) -> BodyAndCache<'_> {
29 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
31 // Figure out what primary body this item has.
32 let (body_id, return_ty_span) = match tcx.hir().get(id) {
33 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. }) => {
34 (*body_id, decl.output.span())
36 Node::Item(hir::Item {
37 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
40 | Node::ImplItem(hir::ImplItem {
41 kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id),
44 | Node::TraitItem(hir::TraitItem {
45 kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)),
47 }) => (*body_id, decl.output.span()),
48 Node::Item(hir::Item { kind: hir::ItemKind::Static(ty, _, body_id), .. })
49 | Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, body_id), .. })
50 | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. })
51 | Node::TraitItem(hir::TraitItem {
52 kind: hir::TraitItemKind::Const(ty, Some(body_id)),
54 }) => (*body_id, ty.span),
55 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => (*body, tcx.hir().span(*hir_id)),
57 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def_id),
60 tcx.infer_ctxt().enter(|infcx| {
61 let cx = Cx::new(&infcx, id);
62 let body = if cx.tables().tainted_by_errors {
63 build::construct_error(cx, body_id)
64 } else if cx.body_owner_kind.is_fn_or_closure() {
65 // fetch the fully liberated fn signature (that is, all bound
66 // types/lifetimes replaced)
67 let fn_sig = cx.tables().liberated_fn_sigs()[id];
68 let fn_def_id = tcx.hir().local_def_id(id);
70 let safety = match fn_sig.unsafety {
71 hir::Unsafety::Normal => Safety::Safe,
72 hir::Unsafety::Unsafe => Safety::FnUnsafe,
75 let body = tcx.hir().body(body_id);
76 let ty = tcx.type_of(fn_def_id);
77 let mut abi = fn_sig.abi;
78 let implicit_argument = match ty.kind {
80 // HACK(eddyb) Avoid having RustCall on closures,
81 // as it adds unnecessary (and wrong) auto-tupling.
83 vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)]
85 ty::Generator(..) => {
86 let gen_ty = tcx.body_tables(body_id).node_type(id);
88 // The resume argument may be missing, in that case we need to provide it here.
89 // It will always be `()` in this case.
90 if body.params.is_empty() {
92 ArgInfo(gen_ty, None, None, None),
93 ArgInfo(tcx.mk_unit(), None, None, None),
96 vec![ArgInfo(gen_ty, None, None, None)]
102 let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| {
103 let owner_id = tcx.hir().body_owner(body_id);
106 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
107 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
108 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
109 match fn_decl.implicit_self {
110 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
111 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
112 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
113 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
124 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
125 // (as it's created inside the body itself, not passed in from outside).
126 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
128 tcx.require_lang_item(lang_items::VaListTypeLangItem, Some(arg.span));
130 tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()])
132 fn_sig.inputs()[index]
135 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
138 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
140 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
141 let gen_ty = tcx.body_tables(body_id).node_type(id);
142 let gen_sig = match gen_ty.kind {
143 ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(),
144 _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty),
146 (Some(gen_sig.yield_ty), gen_sig.return_ty)
148 (None, fn_sig.output())
151 let mut mir = build::construct_fn(
161 mir.yield_ty = yield_ty;
164 // Get the revealed type of this const. This is *not* the adjusted
165 // type of its body, which may be a subtype of this type. For
169 // static X: fn(&'static ()) = foo;
171 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
172 // is not the same as the type of X. We need the type of the return
173 // place to be the type of the constant because NLL typeck will
176 let return_ty = cx.tables().node_type(id);
178 build::construct_const(cx, body_id, return_ty, return_ty_span)
181 lints::check(tcx, &body, def_id);
183 let mut body = BodyAndCache::new(body);
184 body.ensure_predecessors();
186 // The borrow checker will replace all the regions here with its own
187 // inference variables. There's no point having non-erased regions here.
188 // The exception is `body.user_type_annotations`, which is used unmodified
189 // by borrow checking.
191 !(body.local_decls.has_free_regions()
192 || body.basic_blocks().has_free_regions()
193 || body.var_debug_info.has_free_regions()
194 || body.yield_ty.has_free_regions()),
195 "Unexpected free regions in MIR: {:?}",
203 ///////////////////////////////////////////////////////////////////////////
204 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
206 fn liberated_closure_env_ty(
208 closure_expr_id: hir::HirId,
209 body_id: hir::BodyId,
211 let closure_ty = tcx.body_tables(body_id).node_type(closure_expr_id);
213 let (closure_def_id, closure_substs) = match closure_ty.kind {
214 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
215 _ => bug!("closure expr does not have closure type: {:?}", closure_ty),
218 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
219 tcx.erase_late_bound_regions(&closure_env_ty)
222 #[derive(Debug, PartialEq, Eq)]
224 /// Evaluation is currently within a statement.
226 /// Examples include:
228 /// 2. `let _ = EXPR;`
229 /// 3. `let x = EXPR;`
231 /// If true, then statement discards result from evaluating
232 /// the expression (such as examples 1 and 2 above).
233 ignores_expr_result: bool,
236 /// Evaluation is currently within the tail expression of a block.
238 /// Example: `{ STMT_1; STMT_2; EXPR }`
240 /// If true, then the surrounding context of the block ignores
241 /// the result of evaluating the block's tail expression.
243 /// Example: `let _ = { STMT_1; EXPR };`
244 tail_result_is_ignored: bool,
247 /// Generic mark meaning that the block occurred as a subexpression
248 /// where the result might be used.
250 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
255 fn is_tail_expr(&self) -> bool {
257 BlockFrame::TailExpr { .. } => true,
259 BlockFrame::Statement { .. } | BlockFrame::SubExpr => false,
262 fn is_statement(&self) -> bool {
264 BlockFrame::Statement { .. } => true,
266 BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false,
272 struct BlockContext(Vec<BlockFrame>);
274 struct Builder<'a, 'tcx> {
280 generator_kind: Option<GeneratorKind>,
282 /// The current set of scopes, updated as we traverse;
283 /// see the `scope` module for more details.
284 scopes: scope::Scopes<'tcx>,
286 /// The block-context: each time we build the code within an hair::Block,
287 /// we push a frame here tracking whether we are building a statement or
288 /// if we are pushing the tail expression of the block. This is used to
289 /// embed information in generated temps about whether they were created
290 /// for a block tail expression or not.
292 /// It would be great if we could fold this into `self.scopes`
293 /// somehow, but right now I think that is very tightly tied to
294 /// the code generation in ways that we cannot (or should not)
295 /// start just throwing new entries onto that vector in order to
296 /// distinguish the context of EXPR1 from the context of EXPR2 in
297 /// `{ STMTS; EXPR1 } + EXPR2`.
298 block_context: BlockContext,
300 /// The current unsafe block in scope, even if it is hidden by
301 /// a `PushUnsafeBlock`.
302 unpushed_unsafe: Safety,
304 /// The number of `push_unsafe_block` levels in scope.
305 push_unsafe_count: usize,
307 /// The vector of all scopes that we have created thus far;
308 /// we track this for debuginfo later.
309 source_scopes: IndexVec<SourceScope, SourceScopeData>,
310 source_scope: SourceScope,
312 /// The guard-context: each time we build the guard expression for
313 /// a match arm, we push onto this stack, and then pop when we
314 /// finish building it.
315 guard_context: Vec<GuardFrame>,
317 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
318 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
319 var_indices: HirIdMap<LocalsForNode>,
320 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
321 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
322 upvar_mutbls: Vec<Mutability>,
323 unit_temp: Option<Place<'tcx>>,
325 var_debug_info: Vec<VarDebugInfo<'tcx>>,
327 /// Cached block with the `RESUME` terminator; this is created
328 /// when first set of cleanups are built.
329 cached_resume_block: Option<BasicBlock>,
330 /// Cached block with the `RETURN` terminator.
331 cached_return_block: Option<BasicBlock>,
332 /// Cached block with the `UNREACHABLE` terminator.
333 cached_unreachable_block: Option<BasicBlock>,
336 impl<'a, 'tcx> Builder<'a, 'tcx> {
337 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
338 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
341 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
342 self.var_indices[&id].local_id(for_guard)
350 fn push(&mut self, bf: BlockFrame) {
353 fn pop(&mut self) -> Option<BlockFrame> {
357 /// Traverses the frames on the `BlockContext`, searching for either
358 /// the first block-tail expression frame with no intervening
361 /// Notably, this skips over `SubExpr` frames; this method is
362 /// meant to be used in the context of understanding the
363 /// relationship of a temp (created within some complicated
364 /// expression) with its containing expression, and whether the
365 /// value of that *containing expression* (not the temp!) is
367 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
368 for bf in self.0.iter().rev() {
370 BlockFrame::SubExpr => continue,
371 BlockFrame::Statement { .. } => break,
372 &BlockFrame::TailExpr { tail_result_is_ignored } => {
373 return Some(BlockTailInfo { tail_result_is_ignored });
381 /// Looks at the topmost frame on the BlockContext and reports
382 /// whether its one that would discard a block tail result.
384 /// Unlike `currently_within_ignored_tail_expression`, this does
385 /// *not* skip over `SubExpr` frames: here, we want to know
386 /// whether the block result itself is discarded.
387 fn currently_ignores_tail_results(&self) -> bool {
388 match self.0.last() {
389 // no context: conservatively assume result is read
392 // sub-expression: block result feeds into some computation
393 Some(BlockFrame::SubExpr) => false,
395 // otherwise: use accumulated is_ignored state.
396 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored })
397 | Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
404 /// In the usual case, a `HirId` for an identifier maps to at most
405 /// one `Local` declaration.
408 /// The exceptional case is identifiers in a match arm's pattern
409 /// that are referenced in a guard of that match arm. For these,
410 /// we have `2` Locals.
412 /// * `for_arm_body` is the Local used in the arm body (which is
413 /// just like the `One` case above),
415 /// * `ref_for_guard` is the Local used in the arm's guard (which
416 /// is a reference to a temp that is an alias of
418 ForGuard { ref_for_guard: Local, for_arm_body: Local },
422 struct GuardFrameLocal {
426 impl GuardFrameLocal {
427 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
428 GuardFrameLocal { id }
434 /// These are the id's of names that are bound by patterns of the
435 /// arm of *this* guard.
437 /// (Frames higher up the stack will have the id's bound in arms
438 /// further out, such as in a case like:
441 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
444 /// here, when building for FIXME.
445 locals: Vec<GuardFrameLocal>,
448 /// `ForGuard` indicates whether we are talking about:
449 /// 1. The variable for use outside of guard expressions, or
450 /// 2. The temp that holds reference to (1.), which is actually what the
451 /// guard expressions see.
452 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
459 fn local_id(&self, for_guard: ForGuard) -> Local {
460 match (self, for_guard) {
461 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard)
463 &LocalsForNode::ForGuard { ref_for_guard: local_id, .. },
464 ForGuard::RefWithinGuard,
466 | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => {
470 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => {
471 bug!("anything with one local should never be within a guard.")
478 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
481 rustc_index::newtype_index! {
482 struct ScopeId { .. }
485 ///////////////////////////////////////////////////////////////////////////
486 /// The `BlockAnd` "monad" packages up the new basic block along with a
487 /// produced value (sometimes just unit, of course). The `unpack!`
488 /// macro (and methods below) makes working with `BlockAnd` much more
491 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
492 struct BlockAnd<T>(BasicBlock, T);
494 trait BlockAndExtension {
495 fn and<T>(self, v: T) -> BlockAnd<T>;
496 fn unit(self) -> BlockAnd<()>;
499 impl BlockAndExtension for BasicBlock {
500 fn and<T>(self, v: T) -> BlockAnd<T> {
504 fn unit(self) -> BlockAnd<()> {
509 /// Update a block pointer and return the value.
510 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
511 macro_rules! unpack {
512 ($x:ident = $c:expr) => {{
513 let BlockAnd(b, v) = $c;
519 let BlockAnd(b, ()) = $c;
524 fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: DefId, _abi: Abi) -> bool {
525 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy.
526 let attrs = &tcx.get_attrs(fn_def_id);
527 let unwind_attr = attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs);
529 // We never unwind, so it's not relevant to stop an unwind.
530 if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
534 // We cannot add landing pads, so don't add one.
535 if tcx.sess.no_landing_pads() {
539 // This is a special case: some functions have a C abi but are meant to
540 // unwind anyway. Don't stop them.
542 None => false, // FIXME(#58794); should be `!(abi == Abi::Rust || abi == Abi::RustCall)`
543 Some(UnwindAttr::Allowed) => false,
544 Some(UnwindAttr::Aborts) => true,
548 ///////////////////////////////////////////////////////////////////////////
549 /// the main entry point for building MIR for a function
551 struct ArgInfo<'tcx>(
554 Option<&'tcx hir::Param<'tcx>>,
555 Option<ImplicitSelfKind>,
558 fn construct_fn<'a, 'tcx, A>(
565 return_ty_span: Span,
566 body: &'tcx hir::Body<'tcx>,
569 A: Iterator<Item = ArgInfo<'tcx>>,
571 let arguments: Vec<_> = arguments.collect();
574 let tcx_hir = tcx.hir();
575 let span = tcx_hir.span(fn_id);
577 let fn_def_id = tcx_hir.local_def_id(fn_id);
579 let mut builder = Builder::new(
589 let call_site_scope =
590 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite };
592 region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments };
593 let mut block = START_BLOCK;
594 let source_info = builder.source_info(span);
595 let call_site_s = (call_site_scope, source_info);
597 block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
598 if should_abort_on_panic(tcx, fn_def_id, abi) {
599 builder.schedule_abort();
602 let arg_scope_s = (arg_scope, source_info);
603 // `return_block` is called when we evaluate a `return` expression, so
604 // we just use `START_BLOCK` here.
606 block = builder.in_breakable_scope(
609 Place::return_place(),
611 builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
612 builder.args_and_body(
623 // Attribute epilogue to function's closing brace
624 let fn_end = span.shrink_to_hi();
625 let source_info = builder.source_info(fn_end);
626 let return_block = builder.return_block();
627 builder.cfg.goto(block, source_info, return_block);
628 builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
629 // Attribute any unreachable codepaths to the function's closing brace
630 if let Some(unreachable_block) = builder.cached_unreachable_block {
631 builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable);
636 assert_eq!(block, builder.return_block());
638 let spread_arg = if abi == Abi::RustCall {
639 // RustCall pseudo-ABI untuples the last argument.
640 Some(Local::new(arguments.len()))
644 debug!("fn_id {:?} has attrs {:?}", fn_def_id, tcx.get_attrs(fn_def_id));
646 let mut body = builder.finish();
647 body.spread_arg = spread_arg;
651 fn construct_const<'a, 'tcx>(
653 body_id: hir::BodyId,
658 let owner_id = tcx.hir().body_owner(body_id);
659 let span = tcx.hir().span(owner_id);
660 let mut builder = Builder::new(hir, span, 0, Safety::Safe, const_ty, const_ty_span, None);
662 let mut block = START_BLOCK;
663 let ast_expr = &tcx.hir().body(body_id).value;
664 let expr = builder.hir.mirror(ast_expr);
665 unpack!(block = builder.into_expr(Place::return_place(), block, expr));
667 let source_info = builder.source_info(span);
668 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
670 // Constants can't `return` so a return block should not be created.
671 assert_eq!(builder.cached_return_block, None);
673 // Constants may be match expressions in which case an unreachable block may
674 // be created, so terminate it properly.
675 if let Some(unreachable_block) = builder.cached_unreachable_block {
676 builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable);
682 /// Construct MIR for a item that has had errors in type checking.
684 /// This is required because we may still want to run MIR passes on an item
685 /// with type errors, but normal MIR construction can't handle that in general.
686 fn construct_error<'a, 'tcx>(hir: Cx<'a, 'tcx>, body_id: hir::BodyId) -> Body<'tcx> {
688 let owner_id = tcx.hir().body_owner(body_id);
689 let span = tcx.hir().span(owner_id);
690 let ty = tcx.types.err;
691 let num_params = match hir.body_owner_kind {
692 hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len(),
693 hir::BodyOwnerKind::Closure => {
694 if tcx.hir().body(body_id).generator_kind().is_some() {
695 // Generators have an implicit `self` parameter *and* a possibly
696 // implicit resume parameter.
699 // The implicit self parameter adds another local in MIR.
700 1 + tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len()
703 hir::BodyOwnerKind::Const => 0,
704 hir::BodyOwnerKind::Static(_) => 0,
706 let mut builder = Builder::new(hir, span, num_params, Safety::Safe, ty, span, None);
707 let source_info = builder.source_info(span);
708 // Some MIR passes will expect the number of parameters to match the
709 // function declaration.
710 for _ in 0..num_params {
711 builder.local_decls.push(LocalDecl {
712 mutability: Mutability::Mut,
714 user_ty: UserTypeProjections::none(),
717 local_info: LocalInfo::Other,
721 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
722 let mut body = builder.finish();
723 if tcx.hir().body(body_id).generator_kind.is_some() {
724 body.yield_ty = Some(ty);
729 impl<'a, 'tcx> Builder<'a, 'tcx> {
737 generator_kind: Option<GeneratorKind>,
738 ) -> Builder<'a, 'tcx> {
739 let lint_level = LintLevel::Explicit(hir.root_lint_level);
740 let mut builder = Builder {
742 cfg: CFG { basic_blocks: IndexVec::new() },
746 scopes: Default::default(),
747 block_context: BlockContext::new(),
748 source_scopes: IndexVec::new(),
749 source_scope: OUTERMOST_SOURCE_SCOPE,
750 guard_context: vec![],
751 push_unsafe_count: 0,
752 unpushed_unsafe: safety,
753 local_decls: IndexVec::from_elem_n(
754 LocalDecl::new_return_place(return_ty, return_span),
757 canonical_user_type_annotations: IndexVec::new(),
758 upvar_mutbls: vec![],
759 var_indices: Default::default(),
761 var_debug_info: vec![],
762 cached_resume_block: None,
763 cached_return_block: None,
764 cached_unreachable_block: None,
767 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
769 builder.new_source_scope(span, lint_level, Some(safety)),
770 OUTERMOST_SOURCE_SCOPE
772 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
777 fn finish(self) -> Body<'tcx> {
778 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
779 if block.terminator.is_none() {
780 span_bug!(self.fn_span, "no terminator on block {:?}", index);
785 self.cfg.basic_blocks,
788 self.canonical_user_type_annotations,
792 self.hir.control_flow_destroyed(),
799 mut block: BasicBlock,
801 arguments: &[ArgInfo<'tcx>],
802 argument_scope: region::Scope,
803 ast_body: &'tcx hir::Expr<'tcx>,
805 // Allocate locals for the function arguments
806 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
807 let source_info = SourceInfo {
808 scope: OUTERMOST_SOURCE_SCOPE,
809 span: arg_opt.map_or(self.fn_span, |arg| arg.pat.span),
811 let arg_local = self.local_decls.push(LocalDecl {
812 mutability: Mutability::Mut,
814 user_ty: UserTypeProjections::none(),
817 local_info: LocalInfo::Other,
821 // If this is a simple binding pattern, give debuginfo a nice name.
822 if let Some(arg) = arg_opt {
823 if let Some(ident) = arg.pat.simple_ident() {
824 self.var_debug_info.push(VarDebugInfo {
827 place: arg_local.into(),
833 let tcx = self.hir.tcx();
834 let tcx_hir = tcx.hir();
835 let hir_tables = self.hir.tables();
837 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
838 // closure and we stored in a map called upvar_list in TypeckTables indexed
839 // with the closure's DefId. Here, we run through that vec of UpvarIds for
840 // the given closure and use the necessary information to create upvar
841 // debuginfo and to fill `self.upvar_mutbls`.
842 if let Some(upvars) = hir_tables.upvar_list.get(&fn_def_id) {
843 let closure_env_arg = Local::new(1);
844 let mut closure_env_projs = vec![];
845 let mut closure_ty = self.local_decls[closure_env_arg].ty;
846 if let ty::Ref(_, ty, _) = closure_ty.kind {
847 closure_env_projs.push(ProjectionElem::Deref);
850 let upvar_substs = match closure_ty.kind {
851 ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
852 ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
853 _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
855 let upvar_tys = upvar_substs.upvar_tys();
856 let upvars_with_tys = upvars.iter().zip(upvar_tys);
857 self.upvar_mutbls = upvars_with_tys
859 .map(|(i, ((&var_id, &upvar_id), ty))| {
860 let capture = hir_tables.upvar_capture(upvar_id);
862 let mut mutability = Mutability::Not;
863 let mut name = kw::Invalid;
864 if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) {
865 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
867 match hir_tables.extract_binding_mode(tcx.sess, pat.hir_id, pat.span) {
868 Some(ty::BindByValue(hir::Mutability::Mut)) => {
869 mutability = Mutability::Mut;
871 Some(_) => mutability = Mutability::Not,
877 let mut projs = closure_env_projs.clone();
878 projs.push(ProjectionElem::Field(Field::new(i), ty));
880 ty::UpvarCapture::ByValue => {}
881 ty::UpvarCapture::ByRef(..) => {
882 projs.push(ProjectionElem::Deref);
886 self.var_debug_info.push(VarDebugInfo {
888 source_info: SourceInfo {
889 scope: OUTERMOST_SOURCE_SCOPE,
890 span: tcx_hir.span(var_id),
893 local: closure_env_arg,
894 projection: tcx.intern_place_elems(&projs),
903 let mut scope = None;
904 // Bind the argument patterns
905 for (index, arg_info) in arguments.iter().enumerate() {
906 // Function arguments always get the first Local indices after the return place
907 let local = Local::new(index + 1);
908 let place = Place::from(local);
909 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
911 // Make sure we drop (parts of) the argument even when not matched on.
913 arg_opt.as_ref().map_or(ast_body.span, |arg| arg.pat.span),
919 if let Some(arg) = arg_opt {
920 let pattern = self.hir.pattern_from_hir(&arg.pat);
921 let original_source_scope = self.source_scope;
922 let span = pattern.span;
923 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
924 match *pattern.kind {
925 // Don't introduce extra copies for simple bindings
929 mode: BindingMode::ByValue,
933 self.local_decls[local].mutability = mutability;
934 self.local_decls[local].source_info.scope = self.source_scope;
935 self.local_decls[local].local_info = if let Some(kind) = self_binding {
936 LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind)))
938 let binding_mode = ty::BindingMode::BindByValue(mutability);
939 LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
943 opt_match_place: Some((Some(place), span)),
948 self.var_indices.insert(var, LocalsForNode::One(local));
951 scope = self.declare_bindings(
955 matches::ArmHasGuard(false),
956 Some((Some(&place), span)),
958 unpack!(block = self.place_into_pattern(block, pattern, place, false));
961 self.source_scope = original_source_scope;
965 // Enter the argument pattern bindings source scope, if it exists.
966 if let Some(source_scope) = scope {
967 self.source_scope = source_scope;
970 let body = self.hir.mirror(ast_body);
971 self.into(Place::return_place(), block, body)
974 fn set_correct_source_scope_for_arg(
976 arg_hir_id: hir::HirId,
977 original_source_scope: SourceScope,
980 let tcx = self.hir.tcx();
981 let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir.root_lint_level);
982 let parent_root = tcx.maybe_lint_level_root_bounded(
983 self.source_scopes[original_source_scope]
986 .assert_crate_local()
988 self.hir.root_lint_level,
990 if current_root != parent_root {
992 self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
996 fn get_unit_temp(&mut self) -> Place<'tcx> {
997 match self.unit_temp {
1000 let ty = self.hir.unit_ty();
1001 let fn_span = self.fn_span;
1002 let tmp = self.temp(ty, fn_span);
1003 self.unit_temp = Some(tmp);
1009 fn return_block(&mut self) -> BasicBlock {
1010 match self.cached_return_block {
1013 let rb = self.cfg.start_new_block();
1014 self.cached_return_block = Some(rb);
1021 ///////////////////////////////////////////////////////////////////////////
1022 // Builder methods are broken up into modules, depending on what kind
1023 // of thing is being lowered. Note that they use the `unpack` macro
1024 // above extensively.