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 rustc_serialize::{Decodable, Decoder};
36 use transform::MirSource;
41 /// Construct the MIR for a given def-id.
42 pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'tcx> {
43 let id = tcx.hir.as_local_node_id(def_id).unwrap();
45 // Figure out what primary body this item has.
46 let (body_id, return_ty_span) = match tcx.hir.get(id) {
47 Node::Variant(variant) =>
48 return create_constructor_shim(tcx, id, &variant.node.data),
49 Node::StructCtor(ctor) =>
50 return create_constructor_shim(tcx, id, ctor),
52 Node::Expr(hir::Expr { node: hir::ExprKind::Closure(_, decl, body_id, _, _), .. })
53 | Node::Item(hir::Item { node: hir::ItemKind::Fn(decl, _, _, body_id), .. })
56 node: hir::ImplItemKind::Method(hir::MethodSig { decl, .. }, body_id),
62 node: hir::TraitItemKind::Method(
63 hir::MethodSig { decl, .. },
64 hir::TraitMethod::Provided(body_id),
69 (*body_id, decl.output.span())
71 Node::Item(hir::Item { node: hir::ItemKind::Static(ty, _, body_id), .. })
72 | Node::Item(hir::Item { node: hir::ItemKind::Const(ty, body_id), .. })
73 | Node::ImplItem(hir::ImplItem { node: hir::ImplItemKind::Const(ty, body_id), .. })
75 hir::TraitItem { node: hir::TraitItemKind::Const(ty, Some(body_id)), .. }
79 Node::AnonConst(hir::AnonConst { body, id, .. }) => {
80 (*body, tcx.hir.span(*id))
83 _ => span_bug!(tcx.hir.span(id), "can't build MIR for {:?}", def_id),
86 tcx.infer_ctxt().enter(|infcx| {
87 let cx = Cx::new(&infcx, id);
88 let mut mir = if cx.tables().tainted_by_errors {
89 build::construct_error(cx, body_id)
90 } else if let hir::BodyOwnerKind::Fn = cx.body_owner_kind {
91 // fetch the fully liberated fn signature (that is, all bound
92 // types/lifetimes replaced)
93 let fn_hir_id = tcx.hir.node_to_hir_id(id);
94 let fn_sig = cx.tables().liberated_fn_sigs()[fn_hir_id].clone();
95 let fn_def_id = tcx.hir.local_def_id(id);
97 let ty = tcx.type_of(fn_def_id);
98 let mut abi = fn_sig.abi;
99 let implicit_argument = match ty.sty {
101 // HACK(eddyb) Avoid having RustCall on closures,
102 // as it adds unnecessary (and wrong) auto-tupling.
104 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
106 ty::Generator(..) => {
107 let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
108 Some(ArgInfo(gen_ty, None, None, None))
113 // FIXME: safety in closures
114 let safety = match fn_sig.unsafety {
115 hir::Unsafety::Normal => Safety::Safe,
116 hir::Unsafety::Unsafe => Safety::FnUnsafe,
118 let safety = if implicit_argument.is_none() && tcx.is_min_const_fn(fn_def_id) {
119 // the body of `const unsafe fn`s is treated like the body of safe `const fn`s
125 let body = tcx.hir.body(body_id);
126 let explicit_arguments =
130 .map(|(index, arg)| {
131 let owner_id = tcx.hir.body_owner(body_id);
134 if let Some(ref fn_decl) = tcx.hir.fn_decl(owner_id) {
135 let ty_hir_id = fn_decl.inputs[index].hir_id;
136 let ty_span = tcx.hir.span(tcx.hir.hir_to_node_id(ty_hir_id));
137 opt_ty_info = Some(ty_span);
138 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
139 match fn_decl.implicit_self {
140 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
141 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
142 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
143 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
153 ArgInfo(fn_sig.inputs()[index], opt_ty_info, Some(&*arg.pat), self_arg)
156 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
158 let (yield_ty, return_ty) = if body.is_generator {
159 let gen_sig = match ty.sty {
160 ty::Generator(gen_def_id, gen_substs, ..) =>
161 gen_substs.sig(gen_def_id, tcx),
163 span_bug!(tcx.hir.span(id), "generator w/o generator type: {:?}", ty),
165 (Some(gen_sig.yield_ty), gen_sig.return_ty)
167 (None, fn_sig.output())
170 build::construct_fn(cx, id, arguments, safety, abi,
171 return_ty, yield_ty, return_ty_span, body)
173 build::construct_const(cx, body_id, return_ty_span)
176 // Convert the Mir to global types.
177 let mut globalizer = GlobalizeMir {
181 globalizer.visit_mir(&mut mir);
183 mem::transmute::<Mir, Mir<'tcx>>(mir)
186 mir_util::dump_mir(tcx, None, "mir_map", &0,
187 MirSource::item(def_id), &mir, |_, _| Ok(()) );
189 lints::check(tcx, &mir, def_id);
195 /// A pass to lift all the types and substitutions in a Mir
196 /// to the global tcx. Sadly, we don't have a "folder" that
197 /// can change 'tcx so we have to transmute afterwards.
198 struct GlobalizeMir<'a, 'gcx: 'a> {
199 tcx: TyCtxt<'a, 'gcx, 'gcx>,
203 impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
204 fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
205 if let Some(lifted) = self.tcx.lift(ty) {
209 "found type `{:?}` with inference types/regions in MIR",
214 fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
215 if let Some(lifted) = self.tcx.lift(region) {
219 "found region `{:?}` with inference types/regions in MIR",
224 fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
225 if let Some(lifted) = self.tcx.lift(constant) {
229 "found constant `{:?}` with inference types/regions in MIR",
234 fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
235 if let Some(lifted) = self.tcx.lift(substs) {
239 "found substs `{:?}` with inference types/regions in MIR",
245 fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
246 ctor_id: ast::NodeId,
247 v: &'tcx hir::VariantData)
250 let span = tcx.hir.span(ctor_id);
251 if let hir::VariantData::Tuple(ref fields, ctor_id) = *v {
252 tcx.infer_ctxt().enter(|infcx| {
253 let mut mir = shim::build_adt_ctor(&infcx, ctor_id, fields, span);
255 // Convert the Mir to global types.
256 let tcx = infcx.tcx.global_tcx();
257 let mut globalizer = GlobalizeMir {
261 globalizer.visit_mir(&mut mir);
263 mem::transmute::<Mir, Mir<'tcx>>(mir)
266 mir_util::dump_mir(tcx, None, "mir_map", &0,
267 MirSource::item(tcx.hir.local_def_id(ctor_id)),
268 &mir, |_, _| Ok(()) );
273 span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v);
277 ///////////////////////////////////////////////////////////////////////////
278 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
280 fn liberated_closure_env_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
281 closure_expr_id: ast::NodeId,
282 body_id: hir::BodyId)
284 let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id);
285 let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id);
287 let (closure_def_id, closure_substs) = match closure_ty.sty {
288 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
289 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
292 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
293 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
296 #[derive(Debug, PartialEq, Eq)]
297 pub enum BlockFrame {
298 /// Evaluation is currently within a statement.
300 /// Examples include:
302 /// 2. `let _ = EXPR;`
303 /// 3. `let x = EXPR;`
305 /// If true, then statement discards result from evaluating
306 /// the expression (such as examples 1 and 2 above).
307 ignores_expr_result: bool
310 /// Evaluation is currently within the tail expression of a block.
312 /// Example: `{ STMT_1; STMT_2; EXPR }`
314 /// If true, then the surrounding context of the block ignores
315 /// the result of evaluating the block's tail expression.
317 /// Example: `let _ = { STMT_1; EXPR };`
318 tail_result_is_ignored: bool
321 /// Generic mark meaning that the block occurred as a subexpression
322 /// where the result might be used.
324 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
329 fn is_tail_expr(&self) -> bool {
331 BlockFrame::TailExpr { .. } => true,
333 BlockFrame::Statement { .. } |
334 BlockFrame::SubExpr => false,
337 fn is_statement(&self) -> bool {
339 BlockFrame::Statement { .. } => true,
341 BlockFrame::TailExpr { .. } |
342 BlockFrame::SubExpr => false,
348 struct BlockContext(Vec<BlockFrame>);
350 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
351 hir: Cx<'a, 'gcx, 'tcx>,
357 /// the current set of scopes, updated as we traverse;
358 /// see the `scope` module for more details
359 scopes: Vec<scope::Scope<'tcx>>,
361 /// the block-context: each time we build the code within an hair::Block,
362 /// we push a frame here tracking whether we are building a statement or
363 /// if we are pushing the tail expression of the block. This is used to
364 /// embed information in generated temps about whether they were created
365 /// for a block tail expression or not.
367 /// It would be great if we could fold this into `self.scopes`
368 /// somehow; but right now I think that is very tightly tied to
369 /// the code generation in ways that we cannot (or should not)
370 /// start just throwing new entries onto that vector in order to
371 /// distinguish the context of EXPR1 from the context of EXPR2 in
372 /// `{ STMTS; EXPR1 } + EXPR2`
373 block_context: BlockContext,
375 /// The current unsafe block in scope, even if it is hidden by
376 /// a PushUnsafeBlock
377 unpushed_unsafe: Safety,
379 /// The number of `push_unsafe_block` levels in scope
380 push_unsafe_count: usize,
382 /// the current set of breakables; see the `scope` module for more
384 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
386 /// the vector of all scopes that we have created thus far;
387 /// we track this for debuginfo later
388 source_scopes: IndexVec<SourceScope, SourceScopeData>,
389 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
390 source_scope: SourceScope,
392 /// the guard-context: each time we build the guard expression for
393 /// a match arm, we push onto this stack, and then pop when we
394 /// finish building it.
395 guard_context: Vec<GuardFrame>,
397 /// Maps node ids of variable bindings to the `Local`s created for them.
398 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
399 var_indices: NodeMap<LocalsForNode>,
400 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
401 upvar_decls: Vec<UpvarDecl>,
402 unit_temp: Option<Place<'tcx>>,
404 /// cached block with the RESUME terminator; this is created
405 /// when first set of cleanups are built.
406 cached_resume_block: Option<BasicBlock>,
407 /// cached block with the RETURN terminator
408 cached_return_block: Option<BasicBlock>,
409 /// cached block with the UNREACHABLE terminator
410 cached_unreachable_block: Option<BasicBlock>,
413 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
414 fn is_bound_var_in_guard(&self, id: ast::NodeId) -> bool {
415 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
418 fn var_local_id(&self, id: ast::NodeId, for_guard: ForGuard) -> Local {
419 self.var_indices[&id].local_id(for_guard)
424 fn new() -> Self { BlockContext(vec![]) }
425 fn push(&mut self, bf: BlockFrame) { self.0.push(bf); }
426 fn pop(&mut self) -> Option<BlockFrame> { self.0.pop() }
428 /// Traverses the frames on the BlockContext, searching for either
429 /// the first block-tail expression frame with no intervening
432 /// Notably, this skips over `SubExpr` frames; this method is
433 /// meant to be used in the context of understanding the
434 /// relationship of a temp (created within some complicated
435 /// expression) with its containing expression, and whether the
436 /// value of that *containing expression* (not the temp!) is
438 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
439 for bf in self.0.iter().rev() {
441 BlockFrame::SubExpr => continue,
442 BlockFrame::Statement { .. } => break,
443 &BlockFrame::TailExpr { tail_result_is_ignored } =>
444 return Some(BlockTailInfo { tail_result_is_ignored })
451 /// Looks at the topmost frame on the BlockContext and reports
452 /// whether its one that would discard a block tail result.
454 /// Unlike `currently_within_ignored_tail_expression`, this does
455 /// *not* skip over `SubExpr` frames: here, we want to know
456 /// whether the block result itself is discarded.
457 fn currently_ignores_tail_results(&self) -> bool {
458 match self.0.last() {
459 // no context: conservatively assume result is read
462 // sub-expression: block result feeds into some computation
463 Some(BlockFrame::SubExpr) => false,
465 // otherwise: use accumulated is_ignored state.
466 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored }) |
467 Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
474 /// In the usual case, a node-id for an identifier maps to at most
475 /// one Local declaration.
478 /// The exceptional case is identifiers in a match arm's pattern
479 /// that are referenced in a guard of that match arm. For these,
480 /// we can have `2+k` Locals, where `k` is the number of candidate
481 /// patterns (separated by `|`) in the arm.
483 /// * `for_arm_body` is the Local used in the arm body (which is
484 /// just like the `One` case above),
486 /// * `ref_for_guard` is the Local used in the arm's guard (which
487 /// is a reference to a temp that is an alias of
490 /// * `vals_for_guard` is the `k` Locals; at most one of them will
491 /// get initialized by the arm's execution, and after it is
492 /// initialized, `ref_for_guard` will be assigned a reference to
495 /// There reason we have `k` Locals rather than just 1 is to
496 /// accommodate some restrictions imposed by two-phase borrows,
497 /// which apply when we have a `ref mut` pattern.
498 ForGuard { vals_for_guard: Vec<Local>, ref_for_guard: Local, for_arm_body: Local },
502 struct GuardFrameLocal {
506 impl GuardFrameLocal {
507 fn new(id: ast::NodeId, _binding_mode: BindingMode) -> Self {
516 /// These are the id's of names that are bound by patterns of the
517 /// arm of *this* guard.
519 /// (Frames higher up the stack will have the id's bound in arms
520 /// further out, such as in a case like:
523 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
526 /// here, when building for FIXME
527 locals: Vec<GuardFrameLocal>,
530 /// ForGuard indicates whether we are talking about:
531 /// 1. the temp for a local binding used solely within guard expressions,
532 /// 2. the temp that holds reference to (1.), which is actually what the
533 /// guard expressions see, or
534 /// 3. the temp for use outside of guard expressions.
535 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
537 /// The `usize` identifies for which candidate pattern we want the
538 /// local binding. We keep a temp per-candidate to accommodate
539 /// two-phase borrows (see `LocalsForNode` documentation).
540 ValWithinGuard(usize),
546 fn local_id(&self, for_guard: ForGuard) -> Local {
547 match (self, for_guard) {
548 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
549 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
550 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
553 (&LocalsForNode::ForGuard { ref vals_for_guard, .. },
554 ForGuard::ValWithinGuard(pat_idx)) =>
555 vals_for_guard[pat_idx],
557 (&LocalsForNode::One(_), ForGuard::ValWithinGuard(_)) |
558 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
559 bug!("anything with one local should never be within a guard."),
565 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
569 pub struct ScopeId { .. }
572 ///////////////////////////////////////////////////////////////////////////
573 /// The `BlockAnd` "monad" packages up the new basic block along with a
574 /// produced value (sometimes just unit, of course). The `unpack!`
575 /// macro (and methods below) makes working with `BlockAnd` much more
578 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
579 struct BlockAnd<T>(BasicBlock, T);
581 trait BlockAndExtension {
582 fn and<T>(self, v: T) -> BlockAnd<T>;
583 fn unit(self) -> BlockAnd<()>;
586 impl BlockAndExtension for BasicBlock {
587 fn and<T>(self, v: T) -> BlockAnd<T> {
591 fn unit(self) -> BlockAnd<()> {
596 /// Update a block pointer and return the value.
597 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
598 macro_rules! unpack {
599 ($x:ident = $c:expr) => {
601 let BlockAnd(b, v) = $c;
609 let BlockAnd(b, ()) = $c;
615 fn should_abort_on_panic<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
619 // Not callable from C, so we can safely unwind through these
620 if abi == Abi::Rust || abi == Abi::RustCall { return false; }
622 // We never unwind, so it's not relevant to stop an unwind
623 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
625 // We cannot add landing pads, so don't add one
626 if tcx.sess.no_landing_pads() { return false; }
628 // This is a special case: some functions have a C abi but are meant to
629 // unwind anyway. Don't stop them.
630 let attrs = &tcx.get_attrs(fn_def_id);
631 match attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs) {
633 // FIXME(rust-lang/rust#48251) -- Had to disable
634 // abort-on-panic for backwards compatibility reasons.
638 Some(UnwindAttr::Allowed) => false,
639 Some(UnwindAttr::Aborts) => true,
643 ///////////////////////////////////////////////////////////////////////////
644 /// the main entry point for building MIR for a function
646 struct ArgInfo<'gcx>(Ty<'gcx>,
648 Option<&'gcx hir::Pat>,
649 Option<ImplicitSelfKind>);
651 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
657 yield_ty: Option<Ty<'gcx>>,
658 return_ty_span: Span,
659 body: &'gcx hir::Body)
661 where A: Iterator<Item=ArgInfo<'gcx>>
663 let arguments: Vec<_> = arguments.collect();
666 let span = tcx.hir.span(fn_id);
668 // Gather the upvars of a closure, if any.
669 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
670 freevars.iter().map(|fv| {
671 let var_id = fv.var_id();
672 let var_hir_id = tcx.hir.node_to_hir_id(var_id);
673 let closure_expr_id = tcx.hir.local_def_id(fn_id);
674 let capture = hir.tables().upvar_capture(ty::UpvarId {
675 var_path: ty::UpvarPath {hir_id: var_hir_id},
676 closure_expr_id: LocalDefId::from_def_id(closure_expr_id),
678 let by_ref = match capture {
679 ty::UpvarCapture::ByValue => false,
680 ty::UpvarCapture::ByRef(..) => true
682 let mut decl = UpvarDecl {
683 debug_name: keywords::Invalid.name(),
684 var_hir_id: ClearCrossCrate::Set(var_hir_id),
686 mutability: Mutability::Not,
688 if let Some(Node::Binding(pat)) = tcx.hir.find(var_id) {
689 if let hir::PatKind::Binding(_, _, ident, _) = pat.node {
690 decl.debug_name = ident.name;
692 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
693 if bm == ty::BindByValue(hir::MutMutable) {
694 decl.mutability = Mutability::Mut;
696 decl.mutability = Mutability::Not;
699 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
707 let mut builder = Builder::new(hir,
715 let fn_def_id = tcx.hir.local_def_id(fn_id);
716 let call_site_scope = region::Scope {
717 id: body.value.hir_id.local_id,
718 data: region::ScopeData::CallSite
720 let arg_scope = region::Scope {
721 id: body.value.hir_id.local_id,
722 data: region::ScopeData::Arguments
724 let mut block = START_BLOCK;
725 let source_info = builder.source_info(span);
726 let call_site_s = (call_site_scope, source_info);
727 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
728 if should_abort_on_panic(tcx, fn_def_id, abi) {
729 builder.schedule_abort();
732 let arg_scope_s = (arg_scope, source_info);
733 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
734 builder.args_and_body(block, &arguments, arg_scope, &body.value)
736 // Attribute epilogue to function's closing brace
737 let fn_end = span.shrink_to_hi();
738 let source_info = builder.source_info(fn_end);
739 let return_block = builder.return_block();
740 builder.cfg.terminate(block, source_info,
741 TerminatorKind::Goto { target: return_block });
742 builder.cfg.terminate(return_block, source_info,
743 TerminatorKind::Return);
744 // Attribute any unreachable codepaths to the function's closing brace
745 if let Some(unreachable_block) = builder.cached_unreachable_block {
746 builder.cfg.terminate(unreachable_block, source_info,
747 TerminatorKind::Unreachable);
751 assert_eq!(block, builder.return_block());
753 let mut spread_arg = None;
754 if abi == Abi::RustCall {
755 // RustCall pseudo-ABI untuples the last argument.
756 spread_arg = Some(Local::new(arguments.len()));
758 let closure_expr_id = tcx.hir.local_def_id(fn_id);
759 info!("fn_id {:?} has attrs {:?}", closure_expr_id,
760 tcx.get_attrs(closure_expr_id));
762 let mut mir = builder.finish(yield_ty);
763 mir.spread_arg = spread_arg;
767 fn construct_const<'a, 'gcx, 'tcx>(
768 hir: Cx<'a, 'gcx, 'tcx>,
769 body_id: hir::BodyId,
773 let ast_expr = &tcx.hir.body(body_id).value;
774 let ty = hir.tables().expr_ty_adjusted(ast_expr);
775 let owner_id = tcx.hir.body_owner(body_id);
776 let span = tcx.hir.span(owner_id);
777 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, ty_span,vec![]);
779 let mut block = START_BLOCK;
780 let expr = builder.hir.mirror(ast_expr);
781 unpack!(block = builder.into_expr(&Place::Local(RETURN_PLACE), block, expr));
783 let source_info = builder.source_info(span);
784 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
786 // Constants can't `return` so a return block should not be created.
787 assert_eq!(builder.cached_return_block, None);
789 // Constants may be match expressions in which case an unreachable block may
790 // be created, so terminate it properly.
791 if let Some(unreachable_block) = builder.cached_unreachable_block {
792 builder.cfg.terminate(unreachable_block, source_info,
793 TerminatorKind::Unreachable);
799 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
800 body_id: hir::BodyId)
802 let owner_id = hir.tcx().hir.body_owner(body_id);
803 let span = hir.tcx().hir.span(owner_id);
804 let ty = hir.tcx().types.err;
805 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, span, vec![]);
806 let source_info = builder.source_info(span);
807 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
811 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
812 fn new(hir: Cx<'a, 'gcx, 'tcx>,
818 upvar_decls: Vec<UpvarDecl>)
819 -> Builder<'a, 'gcx, 'tcx> {
820 let lint_level = LintLevel::Explicit(hir.root_lint_level);
821 let mut builder = Builder {
823 cfg: CFG { basic_blocks: IndexVec::new() },
827 block_context: BlockContext::new(),
828 source_scopes: IndexVec::new(),
829 source_scope: OUTERMOST_SOURCE_SCOPE,
830 source_scope_local_data: IndexVec::new(),
831 guard_context: vec![],
832 push_unsafe_count: 0,
833 unpushed_unsafe: safety,
834 breakable_scopes: vec![],
835 local_decls: IndexVec::from_elem_n(
836 LocalDecl::new_return_place(return_ty, return_span),
840 var_indices: Default::default(),
842 cached_resume_block: None,
843 cached_return_block: None,
844 cached_unreachable_block: None,
847 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
849 builder.new_source_scope(span, lint_level, Some(safety)),
850 OUTERMOST_SOURCE_SCOPE);
851 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
857 yield_ty: Option<Ty<'tcx>>)
859 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
860 if block.terminator.is_none() {
861 span_bug!(self.fn_span, "no terminator on block {:?}", index);
865 Mir::new(self.cfg.basic_blocks,
867 ClearCrossCrate::Set(self.source_scope_local_data),
877 fn args_and_body(&mut self,
878 mut block: BasicBlock,
879 arguments: &[ArgInfo<'gcx>],
880 argument_scope: region::Scope,
881 ast_body: &'gcx hir::Expr)
884 // Allocate locals for the function arguments
885 for &ArgInfo(ty, _, pattern, _) in arguments.iter() {
886 // If this is a simple binding pattern, give the local a name for
887 // debuginfo and so that error reporting knows that this is a user
888 // variable. For any other pattern the pattern introduces new
889 // variables which will be named instead.
891 if let Some(pat) = pattern {
893 hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ident, _)
894 | hir::PatKind::Binding(hir::BindingAnnotation::Mutable, _, ident, _) => {
895 name = Some(ident.name);
901 let source_info = SourceInfo {
902 scope: OUTERMOST_SOURCE_SCOPE,
903 span: pattern.map_or(self.fn_span, |pat| pat.span)
905 self.local_decls.push(LocalDecl {
906 mutability: Mutability::Mut,
908 user_ty: UserTypeProjections::none(),
910 visibility_scope: source_info.scope,
913 is_user_variable: None,
918 let mut scope = None;
919 // Bind the argument patterns
920 for (index, arg_info) in arguments.iter().enumerate() {
921 // Function arguments always get the first Local indices after the return place
922 let local = Local::new(index + 1);
923 let place = Place::Local(local);
924 let &ArgInfo(ty, opt_ty_info, pattern, ref self_binding) = arg_info;
926 if let Some(pattern) = pattern {
927 let pattern = self.hir.pattern_from_hir(pattern);
928 let span = pattern.span;
930 match *pattern.kind {
931 // Don't introduce extra copies for simple bindings
932 PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
933 self.local_decls[local].mutability = mutability;
934 self.local_decls[local].is_user_variable =
935 if let Some(kind) = self_binding {
936 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind)))
938 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
939 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
942 opt_match_place: Some((Some(place.clone()), span)),
946 self.var_indices.insert(var, LocalsForNode::One(local));
949 scope = self.declare_bindings(scope, ast_body.span,
950 LintLevel::Inherited, &[pattern.clone()],
951 matches::ArmHasGuard(false),
952 Some((Some(&place), span)));
953 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
958 // Make sure we drop (parts of) the argument even when not matched on.
960 pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
961 argument_scope, &place, ty,
962 DropKind::Value { cached_block: CachedBlock::default() },
966 // Enter the argument pattern bindings source scope, if it exists.
967 if let Some(source_scope) = scope {
968 self.source_scope = source_scope;
971 let body = self.hir.mirror(ast_body);
972 self.into(&Place::Local(RETURN_PLACE), block, body)
975 fn get_unit_temp(&mut self) -> Place<'tcx> {
976 match self.unit_temp {
977 Some(ref tmp) => tmp.clone(),
979 let ty = self.hir.unit_ty();
980 let fn_span = self.fn_span;
981 let tmp = self.temp(ty, fn_span);
982 self.unit_temp = Some(tmp.clone());
988 fn return_block(&mut self) -> BasicBlock {
989 match self.cached_return_block {
992 let rb = self.cfg.start_new_block();
993 self.cached_return_block = Some(rb);
999 fn unreachable_block(&mut self) -> BasicBlock {
1000 match self.cached_unreachable_block {
1003 let ub = self.cfg.start_new_block();
1004 self.cached_unreachable_block = Some(ub);
1011 ///////////////////////////////////////////////////////////////////////////
1012 // Builder methods are broken up into modules, depending on what kind
1013 // of thing is being lowered. Note that they use the `unpack` macro
1014 // above extensively.