1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 use build::scope::{CachedBlock, DropKind};
15 use hair::{LintLevel, BindingMode, PatternKind};
18 use rustc::hir::def_id::{DefId, LocalDefId};
19 use rustc::middle::region;
21 use rustc::mir::visit::{MutVisitor, TyContext};
22 use rustc::ty::{self, Ty, TyCtxt};
23 use rustc::ty::subst::Substs;
24 use rustc::util::nodemap::NodeMap;
25 use rustc_target::spec::PanicStrategy;
26 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
30 use rustc_target::spec::abi::Abi;
32 use syntax::attr::{self, UnwindAttr};
33 use syntax::symbol::keywords;
35 use transform::MirSource;
40 /// Construct the MIR for a given def-id.
41 pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'tcx> {
42 let id = tcx.hir.as_local_node_id(def_id).unwrap();
44 // Figure out what primary body this item has.
45 let (body_id, return_ty_span) = match tcx.hir.get(id) {
46 Node::Variant(variant) =>
47 return create_constructor_shim(tcx, id, &variant.node.data),
48 Node::StructCtor(ctor) =>
49 return create_constructor_shim(tcx, id, ctor),
51 Node::Expr(hir::Expr { node: hir::ExprKind::Closure(_, decl, body_id, _, _), .. })
52 | Node::Item(hir::Item { node: hir::ItemKind::Fn(decl, _, _, body_id), .. })
55 node: hir::ImplItemKind::Method(hir::MethodSig { decl, .. }, body_id),
61 node: hir::TraitItemKind::Method(
62 hir::MethodSig { decl, .. },
63 hir::TraitMethod::Provided(body_id),
68 (*body_id, decl.output.span())
70 Node::Item(hir::Item { node: hir::ItemKind::Static(ty, _, body_id), .. })
71 | Node::Item(hir::Item { node: hir::ItemKind::Const(ty, body_id), .. })
72 | Node::ImplItem(hir::ImplItem { node: hir::ImplItemKind::Const(ty, body_id), .. })
74 hir::TraitItem { node: hir::TraitItemKind::Const(ty, Some(body_id)), .. }
78 Node::AnonConst(hir::AnonConst { body, id, .. }) => {
79 (*body, tcx.hir.span(*id))
82 _ => span_bug!(tcx.hir.span(id), "can't build MIR for {:?}", def_id),
85 tcx.infer_ctxt().enter(|infcx| {
86 let cx = Cx::new(&infcx, id);
87 let mut mir = if cx.tables().tainted_by_errors {
88 build::construct_error(cx, body_id)
89 } else if let hir::BodyOwnerKind::Fn = cx.body_owner_kind {
90 // fetch the fully liberated fn signature (that is, all bound
91 // types/lifetimes replaced)
92 let fn_hir_id = tcx.hir.node_to_hir_id(id);
93 let fn_sig = cx.tables().liberated_fn_sigs()[fn_hir_id].clone();
94 let fn_def_id = tcx.hir.local_def_id(id);
96 let ty = tcx.type_of(fn_def_id);
97 let mut abi = fn_sig.abi;
98 let implicit_argument = match ty.sty {
100 // HACK(eddyb) Avoid having RustCall on closures,
101 // as it adds unnecessary (and wrong) auto-tupling.
103 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
105 ty::Generator(..) => {
106 let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
107 Some(ArgInfo(gen_ty, None, None, None))
112 let safety = match fn_sig.unsafety {
113 hir::Unsafety::Normal => Safety::Safe,
114 hir::Unsafety::Unsafe if tcx.is_min_const_fn(fn_def_id) => {
115 // As specified in #55607, a `const unsafe fn` differs
116 // from an `unsafe fn` in that its body is still considered
117 // safe code by default.
118 assert!(!implicit_argument.is_none());
121 hir::Unsafety::Unsafe => Safety::FnUnsafe,
124 let body = tcx.hir.body(body_id);
125 let explicit_arguments =
129 .map(|(index, arg)| {
130 let owner_id = tcx.hir.body_owner(body_id);
133 if let Some(ref fn_decl) = tcx.hir.fn_decl(owner_id) {
134 let ty_hir_id = fn_decl.inputs[index].hir_id;
135 let ty_span = tcx.hir.span(tcx.hir.hir_to_node_id(ty_hir_id));
136 opt_ty_info = Some(ty_span);
137 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
138 match fn_decl.implicit_self {
139 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
140 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
141 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
142 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
152 ArgInfo(fn_sig.inputs()[index], opt_ty_info, Some(&*arg.pat), self_arg)
155 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
157 let (yield_ty, return_ty) = if body.is_generator {
158 let gen_sig = match ty.sty {
159 ty::Generator(gen_def_id, gen_substs, ..) =>
160 gen_substs.sig(gen_def_id, tcx),
162 span_bug!(tcx.hir.span(id), "generator w/o generator type: {:?}", ty),
164 (Some(gen_sig.yield_ty), gen_sig.return_ty)
166 (None, fn_sig.output())
169 build::construct_fn(cx, id, arguments, safety, abi,
170 return_ty, yield_ty, return_ty_span, body)
172 build::construct_const(cx, body_id, return_ty_span)
175 // Convert the Mir to global types.
176 let mut globalizer = GlobalizeMir {
180 globalizer.visit_mir(&mut mir);
182 mem::transmute::<Mir, Mir<'tcx>>(mir)
185 mir_util::dump_mir(tcx, None, "mir_map", &0,
186 MirSource::item(def_id), &mir, |_, _| Ok(()) );
188 lints::check(tcx, &mir, def_id);
194 /// A pass to lift all the types and substitutions in a Mir
195 /// to the global tcx. Sadly, we don't have a "folder" that
196 /// can change 'tcx so we have to transmute afterwards.
197 struct GlobalizeMir<'a, 'gcx: 'a> {
198 tcx: TyCtxt<'a, 'gcx, 'gcx>,
202 impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
203 fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
204 if let Some(lifted) = self.tcx.lift(ty) {
208 "found type `{:?}` with inference types/regions in MIR",
213 fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
214 if let Some(lifted) = self.tcx.lift(region) {
218 "found region `{:?}` with inference types/regions in MIR",
223 fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
224 if let Some(lifted) = self.tcx.lift(constant) {
228 "found constant `{:?}` with inference types/regions in MIR",
233 fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
234 if let Some(lifted) = self.tcx.lift(substs) {
238 "found substs `{:?}` with inference types/regions in MIR",
244 fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
245 ctor_id: ast::NodeId,
246 v: &'tcx hir::VariantData)
249 let span = tcx.hir.span(ctor_id);
250 if let hir::VariantData::Tuple(ref fields, ctor_id) = *v {
251 tcx.infer_ctxt().enter(|infcx| {
252 let mut mir = shim::build_adt_ctor(&infcx, ctor_id, fields, span);
254 // Convert the Mir to global types.
255 let tcx = infcx.tcx.global_tcx();
256 let mut globalizer = GlobalizeMir {
260 globalizer.visit_mir(&mut mir);
262 mem::transmute::<Mir, Mir<'tcx>>(mir)
265 mir_util::dump_mir(tcx, None, "mir_map", &0,
266 MirSource::item(tcx.hir.local_def_id(ctor_id)),
267 &mir, |_, _| Ok(()) );
272 span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v);
276 ///////////////////////////////////////////////////////////////////////////
277 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
279 fn liberated_closure_env_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
280 closure_expr_id: ast::NodeId,
281 body_id: hir::BodyId)
283 let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id);
284 let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id);
286 let (closure_def_id, closure_substs) = match closure_ty.sty {
287 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
288 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
291 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
292 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
295 #[derive(Debug, PartialEq, Eq)]
296 pub enum BlockFrame {
297 /// Evaluation is currently within a statement.
299 /// Examples include:
301 /// 2. `let _ = EXPR;`
302 /// 3. `let x = EXPR;`
304 /// If true, then statement discards result from evaluating
305 /// the expression (such as examples 1 and 2 above).
306 ignores_expr_result: bool
309 /// Evaluation is currently within the tail expression of a block.
311 /// Example: `{ STMT_1; STMT_2; EXPR }`
313 /// If true, then the surrounding context of the block ignores
314 /// the result of evaluating the block's tail expression.
316 /// Example: `let _ = { STMT_1; EXPR };`
317 tail_result_is_ignored: bool
320 /// Generic mark meaning that the block occurred as a subexpression
321 /// where the result might be used.
323 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
328 fn is_tail_expr(&self) -> bool {
330 BlockFrame::TailExpr { .. } => true,
332 BlockFrame::Statement { .. } |
333 BlockFrame::SubExpr => false,
336 fn is_statement(&self) -> bool {
338 BlockFrame::Statement { .. } => true,
340 BlockFrame::TailExpr { .. } |
341 BlockFrame::SubExpr => false,
347 struct BlockContext(Vec<BlockFrame>);
349 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
350 hir: Cx<'a, 'gcx, 'tcx>,
356 /// the current set of scopes, updated as we traverse;
357 /// see the `scope` module for more details
358 scopes: Vec<scope::Scope<'tcx>>,
360 /// the block-context: each time we build the code within an hair::Block,
361 /// we push a frame here tracking whether we are building a statement or
362 /// if we are pushing the tail expression of the block. This is used to
363 /// embed information in generated temps about whether they were created
364 /// for a block tail expression or not.
366 /// It would be great if we could fold this into `self.scopes`
367 /// somehow; but right now I think that is very tightly tied to
368 /// the code generation in ways that we cannot (or should not)
369 /// start just throwing new entries onto that vector in order to
370 /// distinguish the context of EXPR1 from the context of EXPR2 in
371 /// `{ STMTS; EXPR1 } + EXPR2`
372 block_context: BlockContext,
374 /// The current unsafe block in scope, even if it is hidden by
375 /// a PushUnsafeBlock
376 unpushed_unsafe: Safety,
378 /// The number of `push_unsafe_block` levels in scope
379 push_unsafe_count: usize,
381 /// the current set of breakables; see the `scope` module for more
383 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
385 /// the vector of all scopes that we have created thus far;
386 /// we track this for debuginfo later
387 source_scopes: IndexVec<SourceScope, SourceScopeData>,
388 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
389 source_scope: SourceScope,
391 /// the guard-context: each time we build the guard expression for
392 /// a match arm, we push onto this stack, and then pop when we
393 /// finish building it.
394 guard_context: Vec<GuardFrame>,
396 /// Maps node ids of variable bindings to the `Local`s created for them.
397 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
398 var_indices: NodeMap<LocalsForNode>,
399 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
400 upvar_decls: Vec<UpvarDecl>,
401 unit_temp: Option<Place<'tcx>>,
403 /// cached block with the RESUME terminator; this is created
404 /// when first set of cleanups are built.
405 cached_resume_block: Option<BasicBlock>,
406 /// cached block with the RETURN terminator
407 cached_return_block: Option<BasicBlock>,
408 /// cached block with the UNREACHABLE terminator
409 cached_unreachable_block: Option<BasicBlock>,
412 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
413 fn is_bound_var_in_guard(&self, id: ast::NodeId) -> bool {
414 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
417 fn var_local_id(&self, id: ast::NodeId, for_guard: ForGuard) -> Local {
418 self.var_indices[&id].local_id(for_guard)
423 fn new() -> Self { BlockContext(vec![]) }
424 fn push(&mut self, bf: BlockFrame) { self.0.push(bf); }
425 fn pop(&mut self) -> Option<BlockFrame> { self.0.pop() }
427 /// Traverses the frames on the BlockContext, searching for either
428 /// the first block-tail expression frame with no intervening
431 /// Notably, this skips over `SubExpr` frames; this method is
432 /// meant to be used in the context of understanding the
433 /// relationship of a temp (created within some complicated
434 /// expression) with its containing expression, and whether the
435 /// value of that *containing expression* (not the temp!) is
437 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
438 for bf in self.0.iter().rev() {
440 BlockFrame::SubExpr => continue,
441 BlockFrame::Statement { .. } => break,
442 &BlockFrame::TailExpr { tail_result_is_ignored } =>
443 return Some(BlockTailInfo { tail_result_is_ignored })
450 /// Looks at the topmost frame on the BlockContext and reports
451 /// whether its one that would discard a block tail result.
453 /// Unlike `currently_within_ignored_tail_expression`, this does
454 /// *not* skip over `SubExpr` frames: here, we want to know
455 /// whether the block result itself is discarded.
456 fn currently_ignores_tail_results(&self) -> bool {
457 match self.0.last() {
458 // no context: conservatively assume result is read
461 // sub-expression: block result feeds into some computation
462 Some(BlockFrame::SubExpr) => false,
464 // otherwise: use accumulated is_ignored state.
465 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored }) |
466 Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
473 /// In the usual case, a node-id for an identifier maps to at most
474 /// one Local declaration.
477 /// The exceptional case is identifiers in a match arm's pattern
478 /// that are referenced in a guard of that match arm. For these,
479 /// we can have `2+k` Locals, where `k` is the number of candidate
480 /// patterns (separated by `|`) in the arm.
482 /// * `for_arm_body` is the Local used in the arm body (which is
483 /// just like the `One` case above),
485 /// * `ref_for_guard` is the Local used in the arm's guard (which
486 /// is a reference to a temp that is an alias of
489 /// * `vals_for_guard` is the `k` Locals; at most one of them will
490 /// get initialized by the arm's execution, and after it is
491 /// initialized, `ref_for_guard` will be assigned a reference to
494 /// There reason we have `k` Locals rather than just 1 is to
495 /// accommodate some restrictions imposed by two-phase borrows,
496 /// which apply when we have a `ref mut` pattern.
497 ForGuard { vals_for_guard: Vec<Local>, ref_for_guard: Local, for_arm_body: Local },
501 struct GuardFrameLocal {
505 impl GuardFrameLocal {
506 fn new(id: ast::NodeId, _binding_mode: BindingMode) -> Self {
515 /// These are the id's of names that are bound by patterns of the
516 /// arm of *this* guard.
518 /// (Frames higher up the stack will have the id's bound in arms
519 /// further out, such as in a case like:
522 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
525 /// here, when building for FIXME
526 locals: Vec<GuardFrameLocal>,
529 /// ForGuard indicates whether we are talking about:
530 /// 1. the temp for a local binding used solely within guard expressions,
531 /// 2. the temp that holds reference to (1.), which is actually what the
532 /// guard expressions see, or
533 /// 3. the temp for use outside of guard expressions.
534 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
536 /// The `usize` identifies for which candidate pattern we want the
537 /// local binding. We keep a temp per-candidate to accommodate
538 /// two-phase borrows (see `LocalsForNode` documentation).
539 ValWithinGuard(usize),
545 fn local_id(&self, for_guard: ForGuard) -> Local {
546 match (self, for_guard) {
547 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
548 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
549 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
552 (&LocalsForNode::ForGuard { ref vals_for_guard, .. },
553 ForGuard::ValWithinGuard(pat_idx)) =>
554 vals_for_guard[pat_idx],
556 (&LocalsForNode::One(_), ForGuard::ValWithinGuard(_)) |
557 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
558 bug!("anything with one local should never be within a guard."),
564 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
568 pub struct ScopeId { .. }
571 ///////////////////////////////////////////////////////////////////////////
572 /// The `BlockAnd` "monad" packages up the new basic block along with a
573 /// produced value (sometimes just unit, of course). The `unpack!`
574 /// macro (and methods below) makes working with `BlockAnd` much more
577 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
578 struct BlockAnd<T>(BasicBlock, T);
580 trait BlockAndExtension {
581 fn and<T>(self, v: T) -> BlockAnd<T>;
582 fn unit(self) -> BlockAnd<()>;
585 impl BlockAndExtension for BasicBlock {
586 fn and<T>(self, v: T) -> BlockAnd<T> {
590 fn unit(self) -> BlockAnd<()> {
595 /// Update a block pointer and return the value.
596 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
597 macro_rules! unpack {
598 ($x:ident = $c:expr) => {
600 let BlockAnd(b, v) = $c;
608 let BlockAnd(b, ()) = $c;
614 fn should_abort_on_panic<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
618 // Not callable from C, so we can safely unwind through these
619 if abi == Abi::Rust || abi == Abi::RustCall { return false; }
621 // We never unwind, so it's not relevant to stop an unwind
622 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
624 // We cannot add landing pads, so don't add one
625 if tcx.sess.no_landing_pads() { return false; }
627 // This is a special case: some functions have a C abi but are meant to
628 // unwind anyway. Don't stop them.
629 let attrs = &tcx.get_attrs(fn_def_id);
630 match attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs) {
632 // FIXME(rust-lang/rust#48251) -- Had to disable
633 // abort-on-panic for backwards compatibility reasons.
637 Some(UnwindAttr::Allowed) => false,
638 Some(UnwindAttr::Aborts) => true,
642 ///////////////////////////////////////////////////////////////////////////
643 /// the main entry point for building MIR for a function
645 struct ArgInfo<'gcx>(Ty<'gcx>,
647 Option<&'gcx hir::Pat>,
648 Option<ImplicitSelfKind>);
650 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
656 yield_ty: Option<Ty<'gcx>>,
657 return_ty_span: Span,
658 body: &'gcx hir::Body)
660 where A: Iterator<Item=ArgInfo<'gcx>>
662 let arguments: Vec<_> = arguments.collect();
665 let span = tcx.hir.span(fn_id);
667 // Gather the upvars of a closure, if any.
668 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
669 freevars.iter().map(|fv| {
670 let var_id = fv.var_id();
671 let var_hir_id = tcx.hir.node_to_hir_id(var_id);
672 let closure_expr_id = tcx.hir.local_def_id(fn_id);
673 let capture = hir.tables().upvar_capture(ty::UpvarId {
674 var_path: ty::UpvarPath {hir_id: var_hir_id},
675 closure_expr_id: LocalDefId::from_def_id(closure_expr_id),
677 let by_ref = match capture {
678 ty::UpvarCapture::ByValue => false,
679 ty::UpvarCapture::ByRef(..) => true
681 let mut decl = UpvarDecl {
682 debug_name: keywords::Invalid.name(),
683 var_hir_id: ClearCrossCrate::Set(var_hir_id),
685 mutability: Mutability::Not,
687 if let Some(Node::Binding(pat)) = tcx.hir.find(var_id) {
688 if let hir::PatKind::Binding(_, _, ident, _) = pat.node {
689 decl.debug_name = ident.name;
691 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
692 if bm == ty::BindByValue(hir::MutMutable) {
693 decl.mutability = Mutability::Mut;
695 decl.mutability = Mutability::Not;
698 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
706 let mut builder = Builder::new(hir,
714 let fn_def_id = tcx.hir.local_def_id(fn_id);
715 let call_site_scope = region::Scope {
716 id: body.value.hir_id.local_id,
717 data: region::ScopeData::CallSite
719 let arg_scope = region::Scope {
720 id: body.value.hir_id.local_id,
721 data: region::ScopeData::Arguments
723 let mut block = START_BLOCK;
724 let source_info = builder.source_info(span);
725 let call_site_s = (call_site_scope, source_info);
726 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
727 if should_abort_on_panic(tcx, fn_def_id, abi) {
728 builder.schedule_abort();
731 let arg_scope_s = (arg_scope, source_info);
732 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
733 builder.args_and_body(block, &arguments, arg_scope, &body.value)
735 // Attribute epilogue to function's closing brace
736 let fn_end = span.shrink_to_hi();
737 let source_info = builder.source_info(fn_end);
738 let return_block = builder.return_block();
739 builder.cfg.terminate(block, source_info,
740 TerminatorKind::Goto { target: return_block });
741 builder.cfg.terminate(return_block, source_info,
742 TerminatorKind::Return);
743 // Attribute any unreachable codepaths to the function's closing brace
744 if let Some(unreachable_block) = builder.cached_unreachable_block {
745 builder.cfg.terminate(unreachable_block, source_info,
746 TerminatorKind::Unreachable);
750 assert_eq!(block, builder.return_block());
752 let mut spread_arg = None;
753 if abi == Abi::RustCall {
754 // RustCall pseudo-ABI untuples the last argument.
755 spread_arg = Some(Local::new(arguments.len()));
757 let closure_expr_id = tcx.hir.local_def_id(fn_id);
758 info!("fn_id {:?} has attrs {:?}", closure_expr_id,
759 tcx.get_attrs(closure_expr_id));
761 let mut mir = builder.finish(yield_ty);
762 mir.spread_arg = spread_arg;
766 fn construct_const<'a, 'gcx, 'tcx>(
767 hir: Cx<'a, 'gcx, 'tcx>,
768 body_id: hir::BodyId,
772 let ast_expr = &tcx.hir.body(body_id).value;
773 let ty = hir.tables().expr_ty_adjusted(ast_expr);
774 let owner_id = tcx.hir.body_owner(body_id);
775 let span = tcx.hir.span(owner_id);
776 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, ty_span,vec![]);
778 let mut block = START_BLOCK;
779 let expr = builder.hir.mirror(ast_expr);
780 unpack!(block = builder.into_expr(&Place::Local(RETURN_PLACE), block, expr));
782 let source_info = builder.source_info(span);
783 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
785 // Constants can't `return` so a return block should not be created.
786 assert_eq!(builder.cached_return_block, None);
788 // Constants may be match expressions in which case an unreachable block may
789 // be created, so terminate it properly.
790 if let Some(unreachable_block) = builder.cached_unreachable_block {
791 builder.cfg.terminate(unreachable_block, source_info,
792 TerminatorKind::Unreachable);
798 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
799 body_id: hir::BodyId)
801 let owner_id = hir.tcx().hir.body_owner(body_id);
802 let span = hir.tcx().hir.span(owner_id);
803 let ty = hir.tcx().types.err;
804 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, span, vec![]);
805 let source_info = builder.source_info(span);
806 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
810 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
811 fn new(hir: Cx<'a, 'gcx, 'tcx>,
817 upvar_decls: Vec<UpvarDecl>)
818 -> Builder<'a, 'gcx, 'tcx> {
819 let lint_level = LintLevel::Explicit(hir.root_lint_level);
820 let mut builder = Builder {
822 cfg: CFG { basic_blocks: IndexVec::new() },
826 block_context: BlockContext::new(),
827 source_scopes: IndexVec::new(),
828 source_scope: OUTERMOST_SOURCE_SCOPE,
829 source_scope_local_data: IndexVec::new(),
830 guard_context: vec![],
831 push_unsafe_count: 0,
832 unpushed_unsafe: safety,
833 breakable_scopes: vec![],
834 local_decls: IndexVec::from_elem_n(
835 LocalDecl::new_return_place(return_ty, return_span),
839 var_indices: Default::default(),
841 cached_resume_block: None,
842 cached_return_block: None,
843 cached_unreachable_block: None,
846 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
848 builder.new_source_scope(span, lint_level, Some(safety)),
849 OUTERMOST_SOURCE_SCOPE);
850 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
856 yield_ty: Option<Ty<'tcx>>)
858 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
859 if block.terminator.is_none() {
860 span_bug!(self.fn_span, "no terminator on block {:?}", index);
864 Mir::new(self.cfg.basic_blocks,
866 ClearCrossCrate::Set(self.source_scope_local_data),
876 fn args_and_body(&mut self,
877 mut block: BasicBlock,
878 arguments: &[ArgInfo<'gcx>],
879 argument_scope: region::Scope,
880 ast_body: &'gcx hir::Expr)
883 // Allocate locals for the function arguments
884 for &ArgInfo(ty, _, pattern, _) in arguments.iter() {
885 // If this is a simple binding pattern, give the local a name for
886 // debuginfo and so that error reporting knows that this is a user
887 // variable. For any other pattern the pattern introduces new
888 // variables which will be named instead.
890 if let Some(pat) = pattern {
892 hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ident, _)
893 | hir::PatKind::Binding(hir::BindingAnnotation::Mutable, _, ident, _) => {
894 name = Some(ident.name);
900 let source_info = SourceInfo {
901 scope: OUTERMOST_SOURCE_SCOPE,
902 span: pattern.map_or(self.fn_span, |pat| pat.span)
904 self.local_decls.push(LocalDecl {
905 mutability: Mutability::Mut,
907 user_ty: UserTypeProjections::none(),
909 visibility_scope: source_info.scope,
912 is_user_variable: None,
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::Local(local);
923 let &ArgInfo(ty, opt_ty_info, pattern, ref self_binding) = arg_info;
925 if let Some(pattern) = pattern {
926 let pattern = self.hir.pattern_from_hir(pattern);
927 let span = pattern.span;
929 match *pattern.kind {
930 // Don't introduce extra copies for simple bindings
931 PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
932 self.local_decls[local].mutability = mutability;
933 self.local_decls[local].is_user_variable =
934 if let Some(kind) = self_binding {
935 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind)))
937 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
938 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
941 opt_match_place: Some((Some(place.clone()), span)),
945 self.var_indices.insert(var, LocalsForNode::One(local));
948 scope = self.declare_bindings(scope, ast_body.span,
949 LintLevel::Inherited, &[pattern.clone()],
950 matches::ArmHasGuard(false),
951 Some((Some(&place), span)));
952 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
957 // Make sure we drop (parts of) the argument even when not matched on.
959 pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
960 argument_scope, &place, ty,
961 DropKind::Value { cached_block: CachedBlock::default() },
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::Local(RETURN_PLACE), block, body)
974 fn get_unit_temp(&mut self) -> Place<'tcx> {
975 match self.unit_temp {
976 Some(ref tmp) => tmp.clone(),
978 let ty = self.hir.unit_ty();
979 let fn_span = self.fn_span;
980 let tmp = self.temp(ty, fn_span);
981 self.unit_temp = Some(tmp.clone());
987 fn return_block(&mut self) -> BasicBlock {
988 match self.cached_return_block {
991 let rb = self.cfg.start_new_block();
992 self.cached_return_block = Some(rb);
998 fn unreachable_block(&mut self) -> BasicBlock {
999 match self.cached_unreachable_block {
1002 let ub = self.cfg.start_new_block();
1003 self.cached_unreachable_block = Some(ub);
1010 ///////////////////////////////////////////////////////////////////////////
1011 // Builder methods are broken up into modules, depending on what kind
1012 // of thing is being lowered. Note that they use the `unpack` macro
1013 // above extensively.