2 use rustc::hir::def_id::DefId;
4 use rustc::ty::{self, Ty, TyCtxt};
5 use rustc::ty::layout::VariantIdx;
6 use rustc::ty::subst::{Subst, InternalSubsts};
7 use rustc::ty::query::Providers;
9 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
11 use rustc_target::spec::abi::Abi;
12 use syntax_pos::{Span, sym};
17 use crate::transform::{
18 add_moves_for_packed_drops, add_call_guards,
19 remove_noop_landing_pads, no_landing_pads, simplify, run_passes
21 use crate::util::elaborate_drops::{self, DropElaborator, DropStyle, DropFlagMode};
22 use crate::util::patch::MirPatch;
23 use crate::util::expand_aggregate;
25 pub fn provide(providers: &mut Providers<'_>) {
26 providers.mir_shims = make_shim;
29 fn make_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
30 instance: ty::InstanceDef<'tcx>)
33 debug!("make_shim({:?})", instance);
35 let mut result = match instance {
36 ty::InstanceDef::Item(..) =>
37 bug!("item {:?} passed to make_shim", instance),
38 ty::InstanceDef::VtableShim(def_id) => {
42 Adjustment::DerefMove,
43 CallKind::Direct(def_id),
47 ty::InstanceDef::FnPtrShim(def_id, ty) => {
48 let trait_ = tcx.trait_of_item(def_id).unwrap();
49 let adjustment = match tcx.lang_items().fn_trait_kind(trait_) {
50 Some(ty::ClosureKind::FnOnce) => Adjustment::Identity,
51 Some(ty::ClosureKind::FnMut) |
52 Some(ty::ClosureKind::Fn) => Adjustment::Deref,
53 None => bug!("fn pointer {:?} is not an fn", ty)
55 // HACK: we need the "real" argument types for the MIR,
56 // but because our substs are (Self, Args), where Args
57 // is a tuple, we must include the *concrete* argument
58 // types in the MIR. They will be substituted again with
59 // the param-substs, but because they are concrete, this
60 // will not do any harm.
61 let sig = tcx.erase_late_bound_regions(&ty.fn_sig(tcx));
62 let arg_tys = sig.inputs();
72 ty::InstanceDef::Virtual(def_id, _) => {
73 // We are generating a call back to our def-id, which the
74 // codegen backend knows to turn to an actual virtual call.
79 CallKind::Direct(def_id),
83 ty::InstanceDef::ClosureOnceShim { call_once } => {
84 let fn_mut = tcx.lang_items().fn_mut_trait().unwrap();
85 let call_mut = tcx.global_tcx()
86 .associated_items(fn_mut)
87 .find(|it| it.kind == ty::AssocKind::Method)
94 CallKind::Direct(call_mut),
98 ty::InstanceDef::DropGlue(def_id, ty) => {
99 build_drop_shim(tcx, def_id, ty)
101 ty::InstanceDef::CloneShim(def_id, ty) => {
102 let name = tcx.item_name(def_id);
103 if name == sym::clone {
104 build_clone_shim(tcx, def_id, ty)
105 } else if name == sym::clone_from {
106 debug!("make_shim({:?}: using default trait implementation", instance);
107 return tcx.optimized_mir(def_id);
109 bug!("builtin clone shim {:?} not supported", instance)
112 ty::InstanceDef::Intrinsic(_) => {
113 bug!("creating shims from intrinsics ({:?}) is unsupported", instance)
116 debug!("make_shim({:?}) = untransformed {:?}", instance, result);
118 run_passes(tcx, &mut result, instance, MirPhase::Const, &[
119 &add_moves_for_packed_drops::AddMovesForPackedDrops,
120 &no_landing_pads::NoLandingPads,
121 &remove_noop_landing_pads::RemoveNoopLandingPads,
122 &simplify::SimplifyCfg::new("make_shim"),
123 &add_call_guards::CriticalCallEdges,
126 debug!("make_shim({:?}) = {:?}", instance, result);
128 tcx.arena.alloc(result)
131 #[derive(Copy, Clone, Debug, PartialEq)]
139 #[derive(Copy, Clone, Debug, PartialEq)]
145 fn temp_decl(mutability: Mutability, ty: Ty<'_>, span: Span) -> LocalDecl<'_> {
146 let source_info = SourceInfo { scope: OUTERMOST_SOURCE_SCOPE, span };
150 user_ty: UserTypeProjections::none(),
153 visibility_scope: source_info.scope,
155 is_user_variable: None,
160 fn local_decls_for_sig<'tcx>(sig: &ty::FnSig<'tcx>, span: Span)
161 -> IndexVec<Local, LocalDecl<'tcx>>
163 iter::once(temp_decl(Mutability::Mut, sig.output(), span))
164 .chain(sig.inputs().iter().map(
165 |ity| temp_decl(Mutability::Not, ity, span)))
169 fn build_drop_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
171 ty: Option<Ty<'tcx>>)
174 debug!("build_drop_shim(def_id={:?}, ty={:?})", def_id, ty);
176 // Check if this is a generator, if so, return the drop glue for it
177 if let Some(&ty::TyS { sty: ty::Generator(gen_def_id, substs, _), .. }) = ty {
178 let body = &**tcx.optimized_mir(gen_def_id).generator_drop.as_ref().unwrap();
179 return body.subst(tcx, substs.substs);
182 let substs = if let Some(ty) = ty {
183 tcx.intern_substs(&[ty.into()])
185 InternalSubsts::identity_for_item(tcx, def_id)
187 let sig = tcx.fn_sig(def_id).subst(tcx, substs);
188 let sig = tcx.erase_late_bound_regions(&sig);
189 let span = tcx.def_span(def_id);
191 let source_info = SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE };
193 let return_block = BasicBlock::new(1);
194 let mut blocks = IndexVec::with_capacity(2);
195 let block = |blocks: &mut IndexVec<_, _>, kind| {
196 blocks.push(BasicBlockData {
198 terminator: Some(Terminator { source_info, kind }),
202 block(&mut blocks, TerminatorKind::Goto { target: return_block });
203 block(&mut blocks, TerminatorKind::Return);
205 let mut body = Body::new(
207 IndexVec::from_elem_n(
208 SourceScopeData { span: span, parent_scope: None }, 1
210 ClearCrossCrate::Clear,
213 local_decls_for_sig(&sig, span),
221 if let Some(..) = ty {
222 // The first argument (index 0), but add 1 for the return value.
223 let dropee_ptr = Place::Base(PlaceBase::Local(Local::new(1+0)));
224 if tcx.sess.opts.debugging_opts.mir_emit_retag {
225 // Function arguments should be retagged, and we make this one raw.
226 body.basic_blocks_mut()[START_BLOCK].statements.insert(0, Statement {
228 kind: StatementKind::Retag(RetagKind::Raw, dropee_ptr.clone()),
232 let param_env = tcx.param_env(def_id).with_reveal_all();
233 let mut elaborator = DropShimElaborator {
235 patch: MirPatch::new(&body),
239 let dropee = dropee_ptr.deref();
240 let resume_block = elaborator.patch.resume_block();
241 elaborate_drops::elaborate_drop(
247 elaborate_drops::Unwind::To(resume_block),
252 patch.apply(&mut body);
258 pub struct DropShimElaborator<'a, 'tcx: 'a> {
259 pub body: &'a Body<'tcx>,
260 pub patch: MirPatch<'tcx>,
261 pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
262 pub param_env: ty::ParamEnv<'tcx>,
265 impl<'a, 'tcx> fmt::Debug for DropShimElaborator<'a, 'tcx> {
266 fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
271 impl<'a, 'tcx> DropElaborator<'a, 'tcx> for DropShimElaborator<'a, 'tcx> {
274 fn patch(&mut self) -> &mut MirPatch<'tcx> { &mut self.patch }
275 fn body(&self) -> &'a Body<'tcx> { self.body }
276 fn tcx(&self) -> TyCtxt<'a, 'tcx, 'tcx> { self.tcx }
277 fn param_env(&self) -> ty::ParamEnv<'tcx> { self.param_env }
279 fn drop_style(&self, _path: Self::Path, mode: DropFlagMode) -> DropStyle {
280 if let DropFlagMode::Shallow = mode {
287 fn get_drop_flag(&mut self, _path: Self::Path) -> Option<Operand<'tcx>> {
291 fn clear_drop_flag(&mut self, _location: Location, _path: Self::Path, _mode: DropFlagMode) {
294 fn field_subpath(&self, _path: Self::Path, _field: Field) -> Option<Self::Path> {
297 fn deref_subpath(&self, _path: Self::Path) -> Option<Self::Path> {
300 fn downcast_subpath(&self, _path: Self::Path, _variant: VariantIdx) -> Option<Self::Path> {
303 fn array_subpath(&self, _path: Self::Path, _index: u32, _size: u32) -> Option<Self::Path> {
308 /// Builds a `Clone::clone` shim for `self_ty`. Here, `def_id` is `Clone::clone`.
309 fn build_clone_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
314 debug!("build_clone_shim(def_id={:?})", def_id);
316 let mut builder = CloneShimBuilder::new(tcx, def_id, self_ty);
317 let is_copy = self_ty.is_copy_modulo_regions(tcx, tcx.param_env(def_id), builder.span);
319 let dest = Place::RETURN_PLACE;
320 let src = Place::Base(PlaceBase::Local(Local::new(1+0))).deref();
323 _ if is_copy => builder.copy_shim(),
324 ty::Array(ty, len) => {
325 let len = len.unwrap_usize(tcx);
326 builder.array_shim(dest, src, ty, len)
328 ty::Closure(def_id, substs) => {
329 builder.tuple_like_shim(
331 substs.upvar_tys(def_id, tcx)
334 ty::Tuple(tys) => builder.tuple_like_shim(dest, src, tys.iter().map(|k| k.expect_ty())),
336 bug!("clone shim for `{:?}` which is not `Copy` and is not an aggregate", self_ty)
343 struct CloneShimBuilder<'a, 'tcx: 'a> {
344 tcx: TyCtxt<'a, 'tcx, 'tcx>,
346 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
347 blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
349 sig: ty::FnSig<'tcx>,
352 impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
353 fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
355 self_ty: Ty<'tcx>) -> Self {
356 // we must subst the self_ty because it's
357 // otherwise going to be TySelf and we can't index
358 // or access fields of a Place of type TySelf.
359 let substs = tcx.mk_substs_trait(self_ty, &[]);
360 let sig = tcx.fn_sig(def_id).subst(tcx, substs);
361 let sig = tcx.erase_late_bound_regions(&sig);
362 let span = tcx.def_span(def_id);
367 local_decls: local_decls_for_sig(&sig, span),
368 blocks: IndexVec::new(),
374 fn into_mir(self) -> Body<'tcx> {
377 IndexVec::from_elem_n(
378 SourceScopeData { span: self.span, parent_scope: None }, 1
380 ClearCrossCrate::Clear,
385 self.sig.inputs().len(),
392 fn source_info(&self) -> SourceInfo {
393 SourceInfo { span: self.span, scope: OUTERMOST_SOURCE_SCOPE }
398 statements: Vec<Statement<'tcx>>,
399 kind: TerminatorKind<'tcx>,
402 let source_info = self.source_info();
403 self.blocks.push(BasicBlockData {
405 terminator: Some(Terminator { source_info, kind }),
410 /// Gives the index of an upcoming BasicBlock, with an offset.
411 /// offset=0 will give you the index of the next BasicBlock,
412 /// offset=1 will give the index of the next-to-next block,
413 /// offset=-1 will give you the index of the last-created block
414 fn block_index_offset(&mut self, offset: usize) -> BasicBlock {
415 BasicBlock::new(self.blocks.len() + offset)
418 fn make_statement(&self, kind: StatementKind<'tcx>) -> Statement<'tcx> {
420 source_info: self.source_info(),
425 fn copy_shim(&mut self) {
426 let rcvr = Place::Base(PlaceBase::Local(Local::new(1+0))).deref();
427 let ret_statement = self.make_statement(
428 StatementKind::Assign(
430 box Rvalue::Use(Operand::Copy(rcvr))
433 self.block(vec![ret_statement], TerminatorKind::Return, false);
436 fn make_place(&mut self, mutability: Mutability, ty: Ty<'tcx>) -> Place<'tcx> {
437 let span = self.span;
438 Place::Base(PlaceBase::Local(
439 self.local_decls.push(temp_decl(mutability, ty, span))
453 let substs = tcx.mk_substs_trait(ty, &[]);
455 // `func == Clone::clone(&ty) -> ty`
456 let func_ty = tcx.mk_fn_def(self.def_id, substs);
457 let func = Operand::Constant(box Constant {
461 literal: ty::Const::zero_sized(tcx, func_ty),
464 let ref_loc = self.make_place(
466 tcx.mk_ref(tcx.lifetimes.re_erased, ty::TypeAndMut {
468 mutbl: hir::Mutability::MutImmutable,
472 // `let ref_loc: &ty = &src;`
473 let statement = self.make_statement(
474 StatementKind::Assign(
476 box Rvalue::Ref(tcx.lifetimes.re_erased, BorrowKind::Shared, src)
480 // `let loc = Clone::clone(ref_loc);`
481 self.block(vec![statement], TerminatorKind::Call {
483 args: vec![Operand::Move(ref_loc)],
484 destination: Some((dest, next)),
485 cleanup: Some(cleanup),
494 loop_body: BasicBlock,
495 loop_end: BasicBlock,
500 let cond = self.make_place(Mutability::Mut, tcx.types.bool);
501 let compute_cond = self.make_statement(
502 StatementKind::Assign(
504 box Rvalue::BinaryOp(BinOp::Ne, Operand::Copy(end), Operand::Copy(beg))
508 // `if end != beg { goto loop_body; } else { goto loop_end; }`
511 TerminatorKind::if_(tcx, Operand::Move(cond), loop_body, loop_end),
516 fn make_usize(&self, value: u64) -> Box<Constant<'tcx>> {
519 ty: self.tcx.types.usize,
521 literal: ty::Const::from_usize(self.tcx, value),
525 fn array_shim(&mut self, dest: Place<'tcx>, src: Place<'tcx>, ty: Ty<'tcx>, len: u64) {
527 let span = self.span;
529 let beg = self.local_decls.push(temp_decl(Mutability::Mut, tcx.types.usize, span));
530 let end = self.make_place(Mutability::Not, tcx.types.usize);
533 // `let mut beg = 0;`
538 StatementKind::Assign(
539 Place::Base(PlaceBase::Local(beg)),
540 box Rvalue::Use(Operand::Constant(self.make_usize(0)))
544 StatementKind::Assign(
546 box Rvalue::Use(Operand::Constant(self.make_usize(len)))
550 self.block(inits, TerminatorKind::Goto { target: BasicBlock::new(1) }, false);
557 self.loop_header(Place::Base(PlaceBase::Local(beg)),
564 // `dest[i] = Clone::clone(src[beg])`;
565 // Goto #3 if ok, #5 if unwinding happens.
566 let dest_field = dest.clone().index(beg);
567 let src_field = src.index(beg);
568 self.make_clone_call(dest_field, src_field, ty, BasicBlock::new(3),
574 let statements = vec![
576 StatementKind::Assign(
577 Place::Base(PlaceBase::Local(beg)),
578 box Rvalue::BinaryOp(
580 Operand::Copy(Place::Base(PlaceBase::Local(beg))),
581 Operand::Constant(self.make_usize(1))
586 self.block(statements, TerminatorKind::Goto { target: BasicBlock::new(1) }, false);
590 self.block(vec![], TerminatorKind::Return, false);
594 // `let mut beg = 0;`
597 let beg = self.local_decls.push(temp_decl(Mutability::Mut, tcx.types.usize, span));
598 let init = self.make_statement(
599 StatementKind::Assign(
600 Place::Base(PlaceBase::Local(beg)),
601 box Rvalue::Use(Operand::Constant(self.make_usize(0)))
604 self.block(vec![init], TerminatorKind::Goto { target: BasicBlock::new(6) }, true);
606 // BB #6 (cleanup): loop {
611 self.loop_header(Place::Base(PlaceBase::Local(beg)), Place::Base(PlaceBase::Local(end)),
612 BasicBlock::new(7), BasicBlock::new(9), true);
615 // `drop(dest[beg])`;
616 self.block(vec![], TerminatorKind::Drop {
617 location: dest.index(beg),
618 target: BasicBlock::new(8),
625 let statement = self.make_statement(
626 StatementKind::Assign(
627 Place::Base(PlaceBase::Local(beg)),
628 box Rvalue::BinaryOp(
630 Operand::Copy(Place::Base(PlaceBase::Local(beg))),
631 Operand::Constant(self.make_usize(1))
635 self.block(vec![statement], TerminatorKind::Goto { target: BasicBlock::new(6) }, true);
638 self.block(vec![], TerminatorKind::Resume, true);
641 fn tuple_like_shim<I>(&mut self, dest: Place<'tcx>,
642 src: Place<'tcx>, tys: I)
643 where I: Iterator<Item = Ty<'tcx>> {
644 let mut previous_field = None;
645 for (i, ity) in tys.enumerate() {
646 let field = Field::new(i);
647 let src_field = src.clone().field(field, ity);
649 let dest_field = dest.clone().field(field, ity);
651 // #(2i + 1) is the cleanup block for the previous clone operation
652 let cleanup_block = self.block_index_offset(1);
653 // #(2i + 2) is the next cloning block
654 // (or the Return terminator if this is the last block)
655 let next_block = self.block_index_offset(2);
658 // `dest.i = Clone::clone(&src.i);`
659 // Goto #(2i + 2) if ok, #(2i + 1) if unwinding happens.
660 self.make_clone_call(
668 // BB #(2i + 1) (cleanup)
669 if let Some((previous_field, previous_cleanup)) = previous_field.take() {
670 // Drop previous field and goto previous cleanup block.
671 self.block(vec![], TerminatorKind::Drop {
672 location: previous_field,
673 target: previous_cleanup,
677 // Nothing to drop, just resume.
678 self.block(vec![], TerminatorKind::Resume, true);
681 previous_field = Some((dest_field, cleanup_block));
684 self.block(vec![], TerminatorKind::Return, false);
688 /// Builds a "call" shim for `def_id`. The shim calls the
689 /// function specified by `call_kind`, first adjusting its first
690 /// argument according to `rcvr_adjustment`.
692 /// If `untuple_args` is a vec of types, the second argument of the
693 /// function will be untupled as these types.
694 fn build_call_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
696 rcvr_adjustment: Adjustment,
698 untuple_args: Option<&[Ty<'tcx>]>)
701 debug!("build_call_shim(def_id={:?}, rcvr_adjustment={:?}, \
702 call_kind={:?}, untuple_args={:?})",
703 def_id, rcvr_adjustment, call_kind, untuple_args);
705 let sig = tcx.fn_sig(def_id);
706 let sig = tcx.erase_late_bound_regions(&sig);
707 let span = tcx.def_span(def_id);
709 debug!("build_call_shim: sig={:?}", sig);
711 let mut local_decls = local_decls_for_sig(&sig, span);
712 let source_info = SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE };
714 let rcvr_arg = Local::new(1+0);
715 let rcvr_l = Place::Base(PlaceBase::Local(rcvr_arg));
716 let mut statements = vec![];
718 let rcvr = match rcvr_adjustment {
719 Adjustment::Identity => Operand::Move(rcvr_l),
720 Adjustment::Deref => Operand::Copy(rcvr_l.deref()),
721 Adjustment::DerefMove => {
722 // fn(Self, ...) -> fn(*mut Self, ...)
723 let arg_ty = local_decls[rcvr_arg].ty;
724 assert!(arg_ty.is_self());
725 local_decls[rcvr_arg].ty = tcx.mk_mut_ptr(arg_ty);
727 Operand::Move(rcvr_l.deref())
729 Adjustment::RefMut => {
730 // let rcvr = &mut rcvr;
731 let ref_rcvr = local_decls.push(temp_decl(
733 tcx.mk_ref(tcx.lifetimes.re_erased, ty::TypeAndMut {
735 mutbl: hir::Mutability::MutMutable
739 let borrow_kind = BorrowKind::Mut {
740 allow_two_phase_borrow: false,
742 statements.push(Statement {
744 kind: StatementKind::Assign(
745 Place::Base(PlaceBase::Local(ref_rcvr)),
746 box Rvalue::Ref(tcx.lifetimes.re_erased, borrow_kind, rcvr_l)
749 Operand::Move(Place::Base(PlaceBase::Local(ref_rcvr)))
753 let (callee, mut args) = match call_kind {
754 CallKind::Indirect => (rcvr, vec![]),
755 CallKind::Direct(def_id) => {
756 let ty = tcx.type_of(def_id);
757 (Operand::Constant(box Constant {
761 literal: ty::Const::zero_sized(tcx, ty),
767 if let Some(untuple_args) = untuple_args {
768 args.extend(untuple_args.iter().enumerate().map(|(i, ity)| {
769 let arg_place = Place::Base(PlaceBase::Local(Local::new(1+1)));
770 Operand::Move(arg_place.field(Field::new(i), *ity))
773 args.extend((1..sig.inputs().len()).map(|i| {
774 Operand::Move(Place::Base(PlaceBase::Local(Local::new(1+i))))
778 let n_blocks = if let Adjustment::RefMut = rcvr_adjustment { 5 } else { 2 };
779 let mut blocks = IndexVec::with_capacity(n_blocks);
780 let block = |blocks: &mut IndexVec<_, _>, statements, kind, is_cleanup| {
781 blocks.push(BasicBlockData {
783 terminator: Some(Terminator { source_info, kind }),
789 block(&mut blocks, statements, TerminatorKind::Call {
792 destination: Some((Place::RETURN_PLACE,
793 BasicBlock::new(1))),
794 cleanup: if let Adjustment::RefMut = rcvr_adjustment {
795 Some(BasicBlock::new(3))
802 if let Adjustment::RefMut = rcvr_adjustment {
803 // BB #1 - drop for Self
804 block(&mut blocks, vec![], TerminatorKind::Drop {
805 location: Place::Base(PlaceBase::Local(rcvr_arg)),
806 target: BasicBlock::new(2),
811 block(&mut blocks, vec![], TerminatorKind::Return, false);
812 if let Adjustment::RefMut = rcvr_adjustment {
813 // BB #3 - drop if closure panics
814 block(&mut blocks, vec![], TerminatorKind::Drop {
815 location: Place::Base(PlaceBase::Local(rcvr_arg)),
816 target: BasicBlock::new(4),
821 block(&mut blocks, vec![], TerminatorKind::Resume, true);
824 let mut body = Body::new(
826 IndexVec::from_elem_n(
827 SourceScopeData { span: span, parent_scope: None }, 1
829 ClearCrossCrate::Clear,
839 if let Abi::RustCall = sig.abi {
840 body.spread_arg = Some(Local::new(sig.inputs().len()));
845 pub fn build_adt_ctor<'gcx>(tcx: TyCtxt<'_, 'gcx, 'gcx>, ctor_id: DefId) -> &'gcx Body<'gcx> {
846 debug_assert!(tcx.is_constructor(ctor_id));
848 let span = tcx.hir().span_if_local(ctor_id)
849 .unwrap_or_else(|| bug!("no span for ctor {:?}", ctor_id));
851 let param_env = tcx.param_env(ctor_id);
853 // Normalize the sig.
854 let sig = tcx.fn_sig(ctor_id)
856 .expect("LBR in ADT constructor signature");
857 let sig = tcx.normalize_erasing_regions(param_env, sig);
859 let (adt_def, substs) = match sig.output().sty {
860 ty::Adt(adt_def, substs) => (adt_def, substs),
861 _ => bug!("unexpected type for ADT ctor {:?}", sig.output())
864 debug!("build_ctor: ctor_id={:?} sig={:?}", ctor_id, sig);
866 let local_decls = local_decls_for_sig(&sig, span);
868 let source_info = SourceInfo {
870 scope: OUTERMOST_SOURCE_SCOPE
873 let variant_index = if adt_def.is_enum() {
874 adt_def.variant_index_with_ctor_id(ctor_id)
879 // Generate the following MIR:
881 // (return as Variant).field0 = arg0;
882 // (return as Variant).field1 = arg1;
885 debug!("build_ctor: variant_index={:?}", variant_index);
887 let statements = expand_aggregate(
890 .variants[variant_index]
894 .map(|(idx, field_def)| (
895 Operand::Move(Place::Base(PlaceBase::Local(Local::new(idx + 1)))),
896 field_def.ty(tcx, substs),
898 AggregateKind::Adt(adt_def, variant_index, substs, None, None),
902 let start_block = BasicBlockData {
904 terminator: Some(Terminator {
906 kind: TerminatorKind::Return,
911 let body = Body::new(
912 IndexVec::from_elem_n(start_block, 1),
913 IndexVec::from_elem_n(
914 SourceScopeData { span: span, parent_scope: None }, 1
916 ClearCrossCrate::Clear,
927 crate::util::dump_mir(
932 crate::transform::MirSource::item(ctor_id),
937 tcx.arena.alloc(body)