2 use crate::build::scope::DropKind;
3 use crate::hair::cx::Cx;
4 use crate::hair::{LintLevel, BindingMode, PatternKind};
5 use crate::transform::MirSource;
6 use crate::util as mir_util;
9 use rustc::hir::def_id::DefId;
10 use rustc::middle::region;
12 use rustc::mir::visit::{MutVisitor, TyContext};
13 use rustc::ty::{self, Ty, TyCtxt};
14 use rustc::ty::subst::SubstsRef;
15 use rustc::util::nodemap::HirIdMap;
16 use rustc_target::spec::PanicStrategy;
17 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
20 use rustc_target::spec::abi::Abi;
21 use syntax::attr::{self, UnwindAttr};
22 use syntax::symbol::kw;
27 /// Construct the MIR for a given `DefId`.
28 pub fn mir_build<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, def_id: DefId) -> Body<'tcx> {
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_by_hir_id(id) {
33 Node::Expr(hir::Expr { node: hir::ExprKind::Closure(_, decl, body_id, _, _), .. })
34 | Node::Item(hir::Item { node: hir::ItemKind::Fn(decl, _, _, body_id), .. })
37 node: hir::ImplItemKind::Method(hir::MethodSig { decl, .. }, body_id),
43 node: hir::TraitItemKind::Method(
44 hir::MethodSig { decl, .. },
45 hir::TraitMethod::Provided(body_id),
50 (*body_id, decl.output.span())
52 Node::Item(hir::Item { node: hir::ItemKind::Static(ty, _, body_id), .. })
53 | Node::Item(hir::Item { node: hir::ItemKind::Const(ty, body_id), .. })
54 | Node::ImplItem(hir::ImplItem { node: hir::ImplItemKind::Const(ty, body_id), .. })
56 hir::TraitItem { node: hir::TraitItemKind::Const(ty, Some(body_id)), .. }
60 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
61 (*body, tcx.hir().span_by_hir_id(*hir_id))
64 _ => span_bug!(tcx.hir().span_by_hir_id(id), "can't build MIR for {:?}", def_id),
67 tcx.infer_ctxt().enter(|infcx| {
68 let cx = Cx::new(&infcx, id);
69 let mut body = if cx.tables().tainted_by_errors {
70 build::construct_error(cx, body_id)
71 } else if cx.body_owner_kind.is_fn_or_closure() {
72 // fetch the fully liberated fn signature (that is, all bound
73 // types/lifetimes replaced)
74 let fn_sig = cx.tables().liberated_fn_sigs()[id].clone();
75 let fn_def_id = tcx.hir().local_def_id_from_hir_id(id);
77 let ty = tcx.type_of(fn_def_id);
78 let mut abi = fn_sig.abi;
79 let implicit_argument = match ty.sty {
81 // HACK(eddyb) Avoid having RustCall on closures,
82 // as it adds unnecessary (and wrong) auto-tupling.
84 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
86 ty::Generator(..) => {
87 let gen_ty = tcx.body_tables(body_id).node_type(id);
88 Some(ArgInfo(gen_ty, None, None, None))
93 let safety = match fn_sig.unsafety {
94 hir::Unsafety::Normal => Safety::Safe,
95 hir::Unsafety::Unsafe => Safety::FnUnsafe,
98 let body = tcx.hir().body(body_id);
99 let explicit_arguments =
103 .map(|(index, arg)| {
104 let owner_id = tcx.hir().body_owner(body_id);
107 if let Some(ref fn_decl) = tcx.hir().fn_decl(owner_id) {
108 let ty_hir_id = fn_decl.inputs[index].hir_id;
109 let ty_span = tcx.hir().span_by_hir_id(ty_hir_id);
110 opt_ty_info = Some(ty_span);
111 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
112 match fn_decl.implicit_self {
113 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
114 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
115 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
116 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
127 ArgInfo(fn_sig.inputs()[index], opt_ty_info, Some(&*arg.pat), self_arg)
130 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
132 let (yield_ty, return_ty) = if body.is_generator {
133 let gen_sig = match ty.sty {
134 ty::Generator(gen_def_id, gen_substs, ..) =>
135 gen_substs.sig(gen_def_id, tcx),
137 span_bug!(tcx.hir().span_by_hir_id(id),
138 "generator w/o generator type: {:?}", ty),
140 (Some(gen_sig.yield_ty), gen_sig.return_ty)
142 (None, fn_sig.output())
145 build::construct_fn(cx, id, arguments, safety, abi,
146 return_ty, yield_ty, return_ty_span, body)
148 // Get the revealed type of this const. This is *not* the adjusted
149 // type of its body, which may be a subtype of this type. For
153 // static X: fn(&'static ()) = foo;
155 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
156 // is not the same as the type of X. We need the type of the return
157 // place to be the type of the constant because NLL typeck will
160 let return_ty = cx.tables().node_type(id);
162 build::construct_const(cx, body_id, return_ty, return_ty_span)
165 // Convert the `mir::Body` to global types.
166 let mut globalizer = GlobalizeMir {
170 globalizer.visit_body(&mut body);
172 mem::transmute::<Body<'_>, Body<'tcx>>(body)
175 mir_util::dump_mir(tcx, None, "mir_map", &0,
176 MirSource::item(def_id), &body, |_, _| Ok(()) );
178 lints::check(tcx, &body, def_id);
184 /// A pass to lift all the types and substitutions in a MIR
185 /// to the global tcx. Sadly, we don't have a "folder" that
186 /// can change `'tcx` so we have to transmute afterwards.
187 struct GlobalizeMir<'gcx> {
188 tcx: TyCtxt<'gcx, 'gcx>,
192 impl<'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'gcx> {
193 fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
194 if let Some(lifted) = self.tcx.lift(ty) {
198 "found type `{:?}` with inference types/regions in MIR",
203 fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
204 if let Some(lifted) = self.tcx.lift(region) {
208 "found region `{:?}` with inference types/regions in MIR",
213 fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
214 if let Some(lifted) = self.tcx.lift(constant) {
218 "found constant `{:?}` with inference types/regions in MIR",
223 fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, _: Location) {
224 if let Some(lifted) = self.tcx.lift(substs) {
228 "found substs `{:?}` with inference types/regions in MIR",
234 ///////////////////////////////////////////////////////////////////////////
235 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
237 fn liberated_closure_env_ty<'gcx, 'tcx>(
238 tcx: TyCtxt<'gcx, 'tcx>,
239 closure_expr_id: hir::HirId,
240 body_id: hir::BodyId,
242 let closure_ty = tcx.body_tables(body_id).node_type(closure_expr_id);
244 let (closure_def_id, closure_substs) = match closure_ty.sty {
245 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
246 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
249 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
250 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
253 #[derive(Debug, PartialEq, Eq)]
254 pub enum BlockFrame {
255 /// Evaluation is currently within a statement.
257 /// Examples include:
259 /// 2. `let _ = EXPR;`
260 /// 3. `let x = EXPR;`
262 /// If true, then statement discards result from evaluating
263 /// the expression (such as examples 1 and 2 above).
264 ignores_expr_result: bool
267 /// Evaluation is currently within the tail expression of a block.
269 /// Example: `{ STMT_1; STMT_2; EXPR }`
271 /// If true, then the surrounding context of the block ignores
272 /// the result of evaluating the block's tail expression.
274 /// Example: `let _ = { STMT_1; EXPR };`
275 tail_result_is_ignored: bool
278 /// Generic mark meaning that the block occurred as a subexpression
279 /// where the result might be used.
281 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
286 fn is_tail_expr(&self) -> bool {
288 BlockFrame::TailExpr { .. } => true,
290 BlockFrame::Statement { .. } |
291 BlockFrame::SubExpr => false,
294 fn is_statement(&self) -> bool {
296 BlockFrame::Statement { .. } => true,
298 BlockFrame::TailExpr { .. } |
299 BlockFrame::SubExpr => false,
305 struct BlockContext(Vec<BlockFrame>);
307 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
308 hir: Cx<'a, 'gcx, 'tcx>,
315 /// The current set of scopes, updated as we traverse;
316 /// see the `scope` module for more details.
317 scopes: Vec<scope::Scope<'tcx>>,
319 /// The block-context: each time we build the code within an hair::Block,
320 /// we push a frame here tracking whether we are building a statement or
321 /// if we are pushing the tail expression of the block. This is used to
322 /// embed information in generated temps about whether they were created
323 /// for a block tail expression or not.
325 /// It would be great if we could fold this into `self.scopes`
326 /// somehow, but right now I think that is very tightly tied to
327 /// the code generation in ways that we cannot (or should not)
328 /// start just throwing new entries onto that vector in order to
329 /// distinguish the context of EXPR1 from the context of EXPR2 in
330 /// `{ STMTS; EXPR1 } + EXPR2`.
331 block_context: BlockContext,
333 /// The current unsafe block in scope, even if it is hidden by
334 /// a `PushUnsafeBlock`.
335 unpushed_unsafe: Safety,
337 /// The number of `push_unsafe_block` levels in scope.
338 push_unsafe_count: usize,
340 /// The current set of breakables; see the `scope` module for more
342 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
344 /// The vector of all scopes that we have created thus far;
345 /// we track this for debuginfo later.
346 source_scopes: IndexVec<SourceScope, SourceScopeData>,
347 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
348 source_scope: SourceScope,
350 /// The guard-context: each time we build the guard expression for
351 /// a match arm, we push onto this stack, and then pop when we
352 /// finish building it.
353 guard_context: Vec<GuardFrame>,
355 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
356 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
357 var_indices: HirIdMap<LocalsForNode>,
358 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
359 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
360 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
361 upvar_mutbls: Vec<Mutability>,
362 unit_temp: Option<Place<'tcx>>,
364 /// Cached block with the `RESUME` terminator; this is created
365 /// when first set of cleanups are built.
366 cached_resume_block: Option<BasicBlock>,
367 /// Cached block with the `RETURN` terminator.
368 cached_return_block: Option<BasicBlock>,
369 /// Cached block with the `UNREACHABLE` terminator.
370 cached_unreachable_block: Option<BasicBlock>,
373 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
374 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
375 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
378 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
379 self.var_indices[&id].local_id(for_guard)
384 fn new() -> Self { BlockContext(vec![]) }
385 fn push(&mut self, bf: BlockFrame) { self.0.push(bf); }
386 fn pop(&mut self) -> Option<BlockFrame> { self.0.pop() }
388 /// Traverses the frames on the `BlockContext`, searching for either
389 /// the first block-tail expression frame with no intervening
392 /// Notably, this skips over `SubExpr` frames; this method is
393 /// meant to be used in the context of understanding the
394 /// relationship of a temp (created within some complicated
395 /// expression) with its containing expression, and whether the
396 /// value of that *containing expression* (not the temp!) is
398 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
399 for bf in self.0.iter().rev() {
401 BlockFrame::SubExpr => continue,
402 BlockFrame::Statement { .. } => break,
403 &BlockFrame::TailExpr { tail_result_is_ignored } =>
404 return Some(BlockTailInfo { tail_result_is_ignored })
411 /// Looks at the topmost frame on the BlockContext and reports
412 /// whether its one that would discard a block tail result.
414 /// Unlike `currently_within_ignored_tail_expression`, this does
415 /// *not* skip over `SubExpr` frames: here, we want to know
416 /// whether the block result itself is discarded.
417 fn currently_ignores_tail_results(&self) -> bool {
418 match self.0.last() {
419 // no context: conservatively assume result is read
422 // sub-expression: block result feeds into some computation
423 Some(BlockFrame::SubExpr) => false,
425 // otherwise: use accumulated is_ignored state.
426 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored }) |
427 Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
434 /// In the usual case, a `HirId` for an identifier maps to at most
435 /// one `Local` declaration.
438 /// The exceptional case is identifiers in a match arm's pattern
439 /// that are referenced in a guard of that match arm. For these,
440 /// we have `2` Locals.
442 /// * `for_arm_body` is the Local used in the arm body (which is
443 /// just like the `One` case above),
445 /// * `ref_for_guard` is the Local used in the arm's guard (which
446 /// is a reference to a temp that is an alias of
448 ForGuard { ref_for_guard: Local, for_arm_body: Local },
452 struct GuardFrameLocal {
456 impl GuardFrameLocal {
457 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
466 /// These are the id's of names that are bound by patterns of the
467 /// arm of *this* guard.
469 /// (Frames higher up the stack will have the id's bound in arms
470 /// further out, such as in a case like:
473 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
476 /// here, when building for FIXME.
477 locals: Vec<GuardFrameLocal>,
480 /// `ForGuard` indicates whether we are talking about:
481 /// 1. The variable for use outside of guard expressions, or
482 /// 2. The temp that holds reference to (1.), which is actually what the
483 /// guard expressions see.
484 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
491 fn local_id(&self, for_guard: ForGuard) -> Local {
492 match (self, for_guard) {
493 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
494 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
495 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
498 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
499 bug!("anything with one local should never be within a guard."),
505 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
509 pub struct ScopeId { .. }
512 ///////////////////////////////////////////////////////////////////////////
513 /// The `BlockAnd` "monad" packages up the new basic block along with a
514 /// produced value (sometimes just unit, of course). The `unpack!`
515 /// macro (and methods below) makes working with `BlockAnd` much more
518 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
519 struct BlockAnd<T>(BasicBlock, T);
521 trait BlockAndExtension {
522 fn and<T>(self, v: T) -> BlockAnd<T>;
523 fn unit(self) -> BlockAnd<()>;
526 impl BlockAndExtension for BasicBlock {
527 fn and<T>(self, v: T) -> BlockAnd<T> {
531 fn unit(self) -> BlockAnd<()> {
536 /// Update a block pointer and return the value.
537 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
538 macro_rules! unpack {
539 ($x:ident = $c:expr) => {
541 let BlockAnd(b, v) = $c;
549 let BlockAnd(b, ()) = $c;
555 fn should_abort_on_panic<'gcx, 'tcx>(tcx: TyCtxt<'gcx, 'tcx>, fn_def_id: DefId, abi: Abi) -> bool {
556 // Not callable from C, so we can safely unwind through these
557 if abi == Abi::Rust || abi == Abi::RustCall { return false; }
559 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy
560 let attrs = &tcx.get_attrs(fn_def_id);
561 let unwind_attr = attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs);
563 // We never unwind, so it's not relevant to stop an unwind
564 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
566 // We cannot add landing pads, so don't add one
567 if tcx.sess.no_landing_pads() { return false; }
569 // This is a special case: some functions have a C abi but are meant to
570 // unwind anyway. Don't stop them.
573 Some(UnwindAttr::Allowed) => false,
574 Some(UnwindAttr::Aborts) => true,
578 ///////////////////////////////////////////////////////////////////////////
579 /// the main entry point for building MIR for a function
581 struct ArgInfo<'gcx>(Ty<'gcx>, Option<Span>, Option<&'gcx hir::Pat>, Option<ImplicitSelfKind>);
583 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
589 yield_ty: Option<Ty<'gcx>>,
590 return_ty_span: Span,
591 body: &'gcx hir::Body)
593 where A: Iterator<Item=ArgInfo<'gcx>>
595 let arguments: Vec<_> = arguments.collect();
598 let tcx_hir = tcx.hir();
599 let span = tcx_hir.span_by_hir_id(fn_id);
601 let hir_tables = hir.tables();
602 let fn_def_id = tcx_hir.local_def_id_from_hir_id(fn_id);
604 // Gather the upvars of a closure, if any.
605 let mut upvar_mutbls = vec![];
606 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
607 // closure and we stored in a map called upvar_list in TypeckTables indexed
608 // with the closure's DefId. Here, we run through that vec of UpvarIds for
609 // the given closure and use the necessary information to create UpvarDecl.
610 let upvar_debuginfo: Vec<_> = hir_tables
615 .map(|(&var_hir_id, &upvar_id)| {
616 let var_node_id = tcx_hir.hir_to_node_id(var_hir_id);
617 let capture = hir_tables.upvar_capture(upvar_id);
618 let by_ref = match capture {
619 ty::UpvarCapture::ByValue => false,
620 ty::UpvarCapture::ByRef(..) => true,
622 let mut debuginfo = UpvarDebuginfo {
623 debug_name: kw::Invalid,
626 let mut mutability = Mutability::Not;
627 if let Some(Node::Binding(pat)) = tcx_hir.find(var_node_id) {
628 if let hir::PatKind::Binding(_, _, ident, _) = pat.node {
629 debuginfo.debug_name = ident.name;
630 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
631 if bm == ty::BindByValue(hir::MutMutable) {
632 mutability = Mutability::Mut;
634 mutability = Mutability::Not;
637 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
641 upvar_mutbls.push(mutability);
646 let mut builder = Builder::new(hir,
656 let call_site_scope = region::Scope {
657 id: body.value.hir_id.local_id,
658 data: region::ScopeData::CallSite
660 let arg_scope = region::Scope {
661 id: body.value.hir_id.local_id,
662 data: region::ScopeData::Arguments
664 let mut block = START_BLOCK;
665 let source_info = builder.source_info(span);
666 let call_site_s = (call_site_scope, source_info);
667 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
668 if should_abort_on_panic(tcx, fn_def_id, abi) {
669 builder.schedule_abort();
672 let arg_scope_s = (arg_scope, source_info);
673 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
674 builder.args_and_body(block, &arguments, arg_scope, &body.value)
676 // Attribute epilogue to function's closing brace
677 let fn_end = span.shrink_to_hi();
678 let source_info = builder.source_info(fn_end);
679 let return_block = builder.return_block();
680 builder.cfg.terminate(block, source_info,
681 TerminatorKind::Goto { target: return_block });
682 builder.cfg.terminate(return_block, source_info,
683 TerminatorKind::Return);
684 // Attribute any unreachable codepaths to the function's closing brace
685 if let Some(unreachable_block) = builder.cached_unreachable_block {
686 builder.cfg.terminate(unreachable_block, source_info,
687 TerminatorKind::Unreachable);
691 assert_eq!(block, builder.return_block());
693 let mut spread_arg = None;
694 if abi == Abi::RustCall {
695 // RustCall pseudo-ABI untuples the last argument.
696 spread_arg = Some(Local::new(arguments.len()));
698 info!("fn_id {:?} has attrs {:?}", fn_def_id,
699 tcx.get_attrs(fn_def_id));
701 let mut body = builder.finish(yield_ty);
702 body.spread_arg = spread_arg;
706 fn construct_const<'a, 'gcx, 'tcx>(
707 hir: Cx<'a, 'gcx, 'tcx>,
708 body_id: hir::BodyId,
713 let owner_id = tcx.hir().body_owner(body_id);
714 let span = tcx.hir().span(owner_id);
715 let mut builder = Builder::new(
727 let mut block = START_BLOCK;
728 let ast_expr = &tcx.hir().body(body_id).value;
729 let expr = builder.hir.mirror(ast_expr);
730 unpack!(block = builder.into_expr(&Place::RETURN_PLACE, block, expr));
732 let source_info = builder.source_info(span);
733 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
735 // Constants can't `return` so a return block should not be created.
736 assert_eq!(builder.cached_return_block, None);
738 // Constants may be match expressions in which case an unreachable block may
739 // be created, so terminate it properly.
740 if let Some(unreachable_block) = builder.cached_unreachable_block {
741 builder.cfg.terminate(unreachable_block, source_info,
742 TerminatorKind::Unreachable);
748 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
749 body_id: hir::BodyId)
751 let owner_id = hir.tcx().hir().body_owner(body_id);
752 let span = hir.tcx().hir().span(owner_id);
753 let ty = hir.tcx().types.err;
754 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, span, vec![], vec![], false);
755 let source_info = builder.source_info(span);
756 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
760 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
761 fn new(hir: Cx<'a, 'gcx, 'tcx>,
767 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
768 upvar_mutbls: Vec<Mutability>,
770 -> Builder<'a, 'gcx, 'tcx> {
771 let lint_level = LintLevel::Explicit(hir.root_lint_level);
772 let mut builder = Builder {
774 cfg: CFG { basic_blocks: IndexVec::new() },
779 block_context: BlockContext::new(),
780 source_scopes: IndexVec::new(),
781 source_scope: OUTERMOST_SOURCE_SCOPE,
782 source_scope_local_data: IndexVec::new(),
783 guard_context: vec![],
784 push_unsafe_count: 0,
785 unpushed_unsafe: safety,
786 breakable_scopes: vec![],
787 local_decls: IndexVec::from_elem_n(
788 LocalDecl::new_return_place(return_ty, return_span),
791 canonical_user_type_annotations: IndexVec::new(),
792 __upvar_debuginfo_codegen_only_do_not_use,
794 var_indices: Default::default(),
796 cached_resume_block: None,
797 cached_return_block: None,
798 cached_unreachable_block: None,
801 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
803 builder.new_source_scope(span, lint_level, Some(safety)),
804 OUTERMOST_SOURCE_SCOPE);
805 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
811 yield_ty: Option<Ty<'tcx>>)
813 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
814 if block.terminator.is_none() {
815 span_bug!(self.fn_span, "no terminator on block {:?}", index);
820 self.cfg.basic_blocks,
822 ClearCrossCrate::Set(self.source_scope_local_data),
826 self.canonical_user_type_annotations,
828 self.__upvar_debuginfo_codegen_only_do_not_use,
830 self.hir.control_flow_destroyed(),
834 fn args_and_body(&mut self,
835 mut block: BasicBlock,
836 arguments: &[ArgInfo<'gcx>],
837 argument_scope: region::Scope,
838 ast_body: &'gcx hir::Expr)
841 // Allocate locals for the function arguments
842 for &ArgInfo(ty, _, pattern, _) in arguments.iter() {
843 // If this is a simple binding pattern, give the local a name for
844 // debuginfo and so that error reporting knows that this is a user
845 // variable. For any other pattern the pattern introduces new
846 // variables which will be named instead.
847 let (name, span) = if let Some(pat) = pattern {
848 (pat.simple_ident().map(|ident| ident.name), pat.span)
853 let source_info = SourceInfo { scope: OUTERMOST_SOURCE_SCOPE, span, };
854 self.local_decls.push(LocalDecl {
855 mutability: Mutability::Mut,
857 user_ty: UserTypeProjections::none(),
859 visibility_scope: source_info.scope,
862 is_user_variable: None,
867 let mut scope = None;
868 // Bind the argument patterns
869 for (index, arg_info) in arguments.iter().enumerate() {
870 // Function arguments always get the first Local indices after the return place
871 let local = Local::new(index + 1);
872 let place = Place::Base(PlaceBase::Local(local));
873 let &ArgInfo(ty, opt_ty_info, pattern, ref self_binding) = arg_info;
875 // Make sure we drop (parts of) the argument even when not matched on.
877 pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
878 argument_scope, &place, ty, DropKind::Value,
881 if let Some(pattern) = pattern {
882 let pattern = self.hir.pattern_from_hir(pattern);
883 let span = pattern.span;
885 match *pattern.kind {
886 // Don't introduce extra copies for simple bindings
887 PatternKind::Binding {
890 mode: BindingMode::ByValue,
894 self.local_decls[local].mutability = mutability;
895 self.local_decls[local].is_user_variable =
896 if let Some(kind) = self_binding {
897 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind)))
899 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
900 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
903 opt_match_place: Some((Some(place.clone()), span)),
907 self.var_indices.insert(var, LocalsForNode::One(local));
910 scope = self.declare_bindings(
914 matches::ArmHasGuard(false),
915 Some((Some(&place), span)),
917 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
923 // Enter the argument pattern bindings source scope, if it exists.
924 if let Some(source_scope) = scope {
925 self.source_scope = source_scope;
928 let body = self.hir.mirror(ast_body);
929 self.into(&Place::RETURN_PLACE, block, body)
932 fn get_unit_temp(&mut self) -> Place<'tcx> {
933 match self.unit_temp {
934 Some(ref tmp) => tmp.clone(),
936 let ty = self.hir.unit_ty();
937 let fn_span = self.fn_span;
938 let tmp = self.temp(ty, fn_span);
939 self.unit_temp = Some(tmp.clone());
945 fn return_block(&mut self) -> BasicBlock {
946 match self.cached_return_block {
949 let rb = self.cfg.start_new_block();
950 self.cached_return_block = Some(rb);
957 ///////////////////////////////////////////////////////////////////////////
958 // Builder methods are broken up into modules, depending on what kind
959 // of thing is being lowered. Note that they use the `unpack` macro
960 // above extensively.