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;
38 /// Construct the MIR for a given def-id.
39 pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'tcx> {
40 let id = tcx.hir.as_local_node_id(def_id).unwrap();
42 // Figure out what primary body this item has.
43 let body_id = match tcx.hir.get(id) {
44 Node::Variant(variant) =>
45 return create_constructor_shim(tcx, id, &variant.node.data),
46 Node::StructCtor(ctor) =>
47 return create_constructor_shim(tcx, id, ctor),
49 _ => match tcx.hir.maybe_body_owned_by(id) {
51 None => span_bug!(tcx.hir.span(id), "can't build MIR for {:?}", def_id),
55 tcx.infer_ctxt().enter(|infcx| {
56 let cx = Cx::new(&infcx, id);
57 let mut mir = if cx.tables().tainted_by_errors {
58 build::construct_error(cx, body_id)
59 } else if let hir::BodyOwnerKind::Fn = cx.body_owner_kind {
60 // fetch the fully liberated fn signature (that is, all bound
61 // types/lifetimes replaced)
62 let fn_hir_id = tcx.hir.node_to_hir_id(id);
63 let fn_sig = cx.tables().liberated_fn_sigs()[fn_hir_id].clone();
65 let ty = tcx.type_of(tcx.hir.local_def_id(id));
66 let mut abi = fn_sig.abi;
67 let implicit_argument = match ty.sty {
69 // HACK(eddyb) Avoid having RustCall on closures,
70 // as it adds unnecessary (and wrong) auto-tupling.
72 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
74 ty::Generator(..) => {
75 let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
76 Some(ArgInfo(gen_ty, None, None, None))
81 // FIXME: safety in closures
82 let safety = match fn_sig.unsafety {
83 hir::Unsafety::Normal => Safety::Safe,
84 hir::Unsafety::Unsafe => Safety::FnUnsafe,
87 let body = tcx.hir.body(body_id);
88 let explicit_arguments =
93 let owner_id = tcx.hir.body_owner(body_id);
96 if let Some(ref fn_decl) = tcx.hir.fn_decl(owner_id) {
97 let ty_hir_id = fn_decl.inputs[index].hir_id;
98 let ty_span = tcx.hir.span(tcx.hir.hir_to_node_id(ty_hir_id));
99 opt_ty_info = Some(ty_span);
100 self_arg = if index == 0 && fn_decl.has_implicit_self {
101 Some(ImplicitSelfBinding)
109 ArgInfo(fn_sig.inputs()[index], opt_ty_info, Some(&*arg.pat), self_arg)
112 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
114 let (yield_ty, return_ty) = if body.is_generator {
115 let gen_sig = match ty.sty {
116 ty::Generator(gen_def_id, gen_substs, ..) =>
117 gen_substs.sig(gen_def_id, tcx),
119 span_bug!(tcx.hir.span(id), "generator w/o generator type: {:?}", ty),
121 (Some(gen_sig.yield_ty), gen_sig.return_ty)
123 (None, fn_sig.output())
126 build::construct_fn(cx, id, arguments, safety, abi,
127 return_ty, yield_ty, body)
129 build::construct_const(cx, body_id)
132 // Convert the Mir to global types.
133 let mut globalizer = GlobalizeMir {
137 globalizer.visit_mir(&mut mir);
139 mem::transmute::<Mir, Mir<'tcx>>(mir)
142 mir_util::dump_mir(tcx, None, "mir_map", &0,
143 MirSource::item(def_id), &mir, |_, _| Ok(()) );
149 /// A pass to lift all the types and substitutions in a Mir
150 /// to the global tcx. Sadly, we don't have a "folder" that
151 /// can change 'tcx so we have to transmute afterwards.
152 struct GlobalizeMir<'a, 'gcx: 'a> {
153 tcx: TyCtxt<'a, 'gcx, 'gcx>,
157 impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
158 fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
159 if let Some(lifted) = self.tcx.lift(ty) {
163 "found type `{:?}` with inference types/regions in MIR",
168 fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
169 if let Some(lifted) = self.tcx.lift(region) {
173 "found region `{:?}` with inference types/regions in MIR",
178 fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
179 if let Some(lifted) = self.tcx.lift(constant) {
183 "found constant `{:?}` with inference types/regions in MIR",
188 fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
189 if let Some(lifted) = self.tcx.lift(substs) {
193 "found substs `{:?}` with inference types/regions in MIR",
199 fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
200 ctor_id: ast::NodeId,
201 v: &'tcx hir::VariantData)
204 let span = tcx.hir.span(ctor_id);
205 if let hir::VariantData::Tuple(ref fields, ctor_id) = *v {
206 tcx.infer_ctxt().enter(|infcx| {
207 let mut mir = shim::build_adt_ctor(&infcx, ctor_id, fields, span);
209 // Convert the Mir to global types.
210 let tcx = infcx.tcx.global_tcx();
211 let mut globalizer = GlobalizeMir {
215 globalizer.visit_mir(&mut mir);
217 mem::transmute::<Mir, Mir<'tcx>>(mir)
220 mir_util::dump_mir(tcx, None, "mir_map", &0,
221 MirSource::item(tcx.hir.local_def_id(ctor_id)),
222 &mir, |_, _| Ok(()) );
227 span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v);
231 ///////////////////////////////////////////////////////////////////////////
232 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
234 fn liberated_closure_env_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
235 closure_expr_id: ast::NodeId,
236 body_id: hir::BodyId)
238 let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id);
239 let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id);
241 let (closure_def_id, closure_substs) = match closure_ty.sty {
242 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
243 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
246 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
247 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
250 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
251 hir: Cx<'a, 'gcx, 'tcx>,
257 /// the current set of scopes, updated as we traverse;
258 /// see the `scope` module for more details
259 scopes: Vec<scope::Scope<'tcx>>,
261 /// The current unsafe block in scope, even if it is hidden by
262 /// a PushUnsafeBlock
263 unpushed_unsafe: Safety,
265 /// The number of `push_unsafe_block` levels in scope
266 push_unsafe_count: usize,
268 /// the current set of breakables; see the `scope` module for more
270 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
272 /// the vector of all scopes that we have created thus far;
273 /// we track this for debuginfo later
274 source_scopes: IndexVec<SourceScope, SourceScopeData>,
275 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
276 source_scope: SourceScope,
278 /// the guard-context: each time we build the guard expression for
279 /// a match arm, we push onto this stack, and then pop when we
280 /// finish building it.
281 guard_context: Vec<GuardFrame>,
283 /// Maps node ids of variable bindings to the `Local`s created for them.
284 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
285 var_indices: NodeMap<LocalsForNode>,
286 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
287 upvar_decls: Vec<UpvarDecl>,
288 unit_temp: Option<Place<'tcx>>,
290 /// cached block with the RESUME terminator; this is created
291 /// when first set of cleanups are built.
292 cached_resume_block: Option<BasicBlock>,
293 /// cached block with the RETURN terminator
294 cached_return_block: Option<BasicBlock>,
295 /// cached block with the UNREACHABLE terminator
296 cached_unreachable_block: Option<BasicBlock>,
299 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
300 fn is_bound_var_in_guard(&self, id: ast::NodeId) -> bool {
301 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
304 fn var_local_id(&self, id: ast::NodeId, for_guard: ForGuard) -> Local {
305 self.var_indices[&id].local_id(for_guard)
311 /// In the usual case, a node-id for an identifier maps to at most
312 /// one Local declaration.
315 /// The exceptional case is identifiers in a match arm's pattern
316 /// that are referenced in a guard of that match arm. For these,
317 /// we can have `2+k` Locals, where `k` is the number of candidate
318 /// patterns (separated by `|`) in the arm.
320 /// * `for_arm_body` is the Local used in the arm body (which is
321 /// just like the `One` case above),
323 /// * `ref_for_guard` is the Local used in the arm's guard (which
324 /// is a reference to a temp that is an alias of
327 /// * `vals_for_guard` is the `k` Locals; at most one of them will
328 /// get initialized by the arm's execution, and after it is
329 /// initialized, `ref_for_guard` will be assigned a reference to
332 /// There reason we have `k` Locals rather than just 1 is to
333 /// accommodate some restrictions imposed by two-phase borrows,
334 /// which apply when we have a `ref mut` pattern.
335 ForGuard { vals_for_guard: Vec<Local>, ref_for_guard: Local, for_arm_body: Local },
339 struct GuardFrameLocal {
343 impl GuardFrameLocal {
344 fn new(id: ast::NodeId, _binding_mode: BindingMode) -> Self {
353 /// These are the id's of names that are bound by patterns of the
354 /// arm of *this* guard.
356 /// (Frames higher up the stack will have the id's bound in arms
357 /// further out, such as in a case like:
360 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
363 /// here, when building for FIXME
364 locals: Vec<GuardFrameLocal>,
367 /// ForGuard indicates whether we are talking about:
368 /// 1. the temp for a local binding used solely within guard expressions,
369 /// 2. the temp that holds reference to (1.), which is actually what the
370 /// guard expressions see, or
371 /// 3. the temp for use outside of guard expressions.
372 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
374 /// The `usize` identifies for which candidate pattern we want the
375 /// local binding. We keep a temp per-candidate to accommodate
376 /// two-phase borrows (see `LocalsForNode` documentation).
377 ValWithinGuard(usize),
383 fn local_id(&self, for_guard: ForGuard) -> Local {
384 match (self, for_guard) {
385 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
386 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
387 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
390 (&LocalsForNode::ForGuard { ref vals_for_guard, .. },
391 ForGuard::ValWithinGuard(pat_idx)) =>
392 vals_for_guard[pat_idx],
394 (&LocalsForNode::One(_), ForGuard::ValWithinGuard(_)) |
395 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
396 bug!("anything with one local should never be within a guard."),
402 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
406 pub struct ScopeId { .. }
409 ///////////////////////////////////////////////////////////////////////////
410 /// The `BlockAnd` "monad" packages up the new basic block along with a
411 /// produced value (sometimes just unit, of course). The `unpack!`
412 /// macro (and methods below) makes working with `BlockAnd` much more
415 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
416 struct BlockAnd<T>(BasicBlock, T);
418 trait BlockAndExtension {
419 fn and<T>(self, v: T) -> BlockAnd<T>;
420 fn unit(self) -> BlockAnd<()>;
423 impl BlockAndExtension for BasicBlock {
424 fn and<T>(self, v: T) -> BlockAnd<T> {
428 fn unit(self) -> BlockAnd<()> {
433 /// Update a block pointer and return the value.
434 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
435 macro_rules! unpack {
436 ($x:ident = $c:expr) => {
438 let BlockAnd(b, v) = $c;
446 let BlockAnd(b, ()) = $c;
452 fn should_abort_on_panic<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
456 // Not callable from C, so we can safely unwind through these
457 if abi == Abi::Rust || abi == Abi::RustCall { return false; }
459 // We never unwind, so it's not relevant to stop an unwind
460 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
462 // We cannot add landing pads, so don't add one
463 if tcx.sess.no_landing_pads() { return false; }
465 // This is a special case: some functions have a C abi but are meant to
466 // unwind anyway. Don't stop them.
467 let attrs = &tcx.get_attrs(fn_def_id);
468 match attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs) {
470 // FIXME(rust-lang/rust#48251) -- Had to disable
471 // abort-on-panic for backwards compatibility reasons.
475 Some(UnwindAttr::Allowed) => false,
476 Some(UnwindAttr::Aborts) => true,
480 ///////////////////////////////////////////////////////////////////////////
481 /// the main entry point for building MIR for a function
483 struct ImplicitSelfBinding;
485 struct ArgInfo<'gcx>(Ty<'gcx>,
487 Option<&'gcx hir::Pat>,
488 Option<ImplicitSelfBinding>);
490 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
496 yield_ty: Option<Ty<'gcx>>,
497 body: &'gcx hir::Body)
499 where A: Iterator<Item=ArgInfo<'gcx>>
501 let arguments: Vec<_> = arguments.collect();
504 let span = tcx.hir.span(fn_id);
506 // Gather the upvars of a closure, if any.
507 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
508 freevars.iter().map(|fv| {
509 let var_id = fv.var_id();
510 let var_hir_id = tcx.hir.node_to_hir_id(var_id);
511 let closure_expr_id = tcx.hir.local_def_id(fn_id);
512 let capture = hir.tables().upvar_capture(ty::UpvarId {
514 closure_expr_id: LocalDefId::from_def_id(closure_expr_id),
516 let by_ref = match capture {
517 ty::UpvarCapture::ByValue => false,
518 ty::UpvarCapture::ByRef(..) => true
520 let mut decl = UpvarDecl {
521 debug_name: keywords::Invalid.name(),
522 var_hir_id: ClearCrossCrate::Set(var_hir_id),
524 mutability: Mutability::Not,
526 if let Some(Node::Binding(pat)) = tcx.hir.find(var_id) {
527 if let hir::PatKind::Binding(_, _, ident, _) = pat.node {
528 decl.debug_name = ident.name;
530 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
531 if bm == ty::BindByValue(hir::MutMutable) {
532 decl.mutability = Mutability::Mut;
534 decl.mutability = Mutability::Not;
537 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
545 let mut builder = Builder::new(hir.clone(),
552 let fn_def_id = tcx.hir.local_def_id(fn_id);
553 let call_site_scope = region::Scope {
554 id: body.value.hir_id.local_id,
555 data: region::ScopeData::CallSite
557 let arg_scope = region::Scope {
558 id: body.value.hir_id.local_id,
559 data: region::ScopeData::Arguments
561 let mut block = START_BLOCK;
562 let source_info = builder.source_info(span);
563 let call_site_s = (call_site_scope, source_info);
564 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
565 if should_abort_on_panic(tcx, fn_def_id, abi) {
566 builder.schedule_abort();
569 let arg_scope_s = (arg_scope, source_info);
570 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
571 builder.args_and_body(block, &arguments, arg_scope, &body.value)
573 // Attribute epilogue to function's closing brace
574 let fn_end = span.shrink_to_hi();
575 let source_info = builder.source_info(fn_end);
576 let return_block = builder.return_block();
577 builder.cfg.terminate(block, source_info,
578 TerminatorKind::Goto { target: return_block });
579 builder.cfg.terminate(return_block, source_info,
580 TerminatorKind::Return);
581 // Attribute any unreachable codepaths to the function's closing brace
582 if let Some(unreachable_block) = builder.cached_unreachable_block {
583 builder.cfg.terminate(unreachable_block, source_info,
584 TerminatorKind::Unreachable);
588 assert_eq!(block, builder.return_block());
590 let mut spread_arg = None;
591 if abi == Abi::RustCall {
592 // RustCall pseudo-ABI untuples the last argument.
593 spread_arg = Some(Local::new(arguments.len()));
595 let closure_expr_id = tcx.hir.local_def_id(fn_id);
596 info!("fn_id {:?} has attrs {:?}", closure_expr_id,
597 tcx.get_attrs(closure_expr_id));
599 let mut mir = builder.finish(yield_ty);
600 mir.spread_arg = spread_arg;
604 fn construct_const<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
605 body_id: hir::BodyId)
608 let ast_expr = &tcx.hir.body(body_id).value;
609 let ty = hir.tables().expr_ty_adjusted(ast_expr);
610 let owner_id = tcx.hir.body_owner(body_id);
611 let span = tcx.hir.span(owner_id);
612 let mut builder = Builder::new(hir.clone(), span, 0, Safety::Safe, ty, vec![]);
614 let mut block = START_BLOCK;
615 let expr = builder.hir.mirror(ast_expr);
616 unpack!(block = builder.into_expr(&Place::Local(RETURN_PLACE), block, expr));
618 let source_info = builder.source_info(span);
619 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
621 // Constants can't `return` so a return block should not be created.
622 assert_eq!(builder.cached_return_block, None);
624 // Constants may be match expressions in which case an unreachable block may
625 // be created, so terminate it properly.
626 if let Some(unreachable_block) = builder.cached_unreachable_block {
627 builder.cfg.terminate(unreachable_block, source_info,
628 TerminatorKind::Unreachable);
634 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
635 body_id: hir::BodyId)
637 let owner_id = hir.tcx().hir.body_owner(body_id);
638 let span = hir.tcx().hir.span(owner_id);
639 let ty = hir.tcx().types.err;
640 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, vec![]);
641 let source_info = builder.source_info(span);
642 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
646 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
647 fn new(hir: Cx<'a, 'gcx, 'tcx>,
652 upvar_decls: Vec<UpvarDecl>)
653 -> Builder<'a, 'gcx, 'tcx> {
654 let lint_level = LintLevel::Explicit(hir.root_lint_level);
655 let mut builder = Builder {
657 cfg: CFG { basic_blocks: IndexVec::new() },
661 source_scopes: IndexVec::new(),
662 source_scope: OUTERMOST_SOURCE_SCOPE,
663 source_scope_local_data: IndexVec::new(),
664 guard_context: vec![],
665 push_unsafe_count: 0,
666 unpushed_unsafe: safety,
667 breakable_scopes: vec![],
668 local_decls: IndexVec::from_elem_n(LocalDecl::new_return_place(return_ty,
671 var_indices: NodeMap(),
673 cached_resume_block: None,
674 cached_return_block: None,
675 cached_unreachable_block: None,
678 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
680 builder.new_source_scope(span, lint_level, Some(safety)),
681 OUTERMOST_SOURCE_SCOPE);
682 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
688 yield_ty: Option<Ty<'tcx>>)
690 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
691 if block.terminator.is_none() {
692 span_bug!(self.fn_span, "no terminator on block {:?}", index);
696 Mir::new(self.cfg.basic_blocks,
698 ClearCrossCrate::Set(self.source_scope_local_data),
708 fn args_and_body(&mut self,
709 mut block: BasicBlock,
710 arguments: &[ArgInfo<'gcx>],
711 argument_scope: region::Scope,
712 ast_body: &'gcx hir::Expr)
715 // Allocate locals for the function arguments
716 for &ArgInfo(ty, _, pattern, _) in arguments.iter() {
717 // If this is a simple binding pattern, give the local a name for
718 // debuginfo and so that error reporting knows that this is a user
719 // variable. For any other pattern the pattern introduces new
720 // variables which will be named instead.
722 if let Some(pat) = pattern {
724 hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ident, _)
725 | hir::PatKind::Binding(hir::BindingAnnotation::Mutable, _, ident, _) => {
726 name = Some(ident.name);
732 let source_info = SourceInfo {
733 scope: OUTERMOST_SOURCE_SCOPE,
734 span: pattern.map_or(self.fn_span, |pat| pat.span)
736 self.local_decls.push(LocalDecl {
737 mutability: Mutability::Mut,
741 visibility_scope: source_info.scope,
744 is_user_variable: None,
748 let mut scope = None;
749 // Bind the argument patterns
750 for (index, arg_info) in arguments.iter().enumerate() {
751 // Function arguments always get the first Local indices after the return place
752 let local = Local::new(index + 1);
753 let place = Place::Local(local);
754 let &ArgInfo(ty, opt_ty_info, pattern, ref self_binding) = arg_info;
756 if let Some(pattern) = pattern {
757 let pattern = self.hir.pattern_from_hir(pattern);
758 let span = pattern.span;
760 match *pattern.kind {
761 // Don't introduce extra copies for simple bindings
762 PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
763 self.local_decls[local].mutability = mutability;
764 self.local_decls[local].is_user_variable =
765 if let Some(ImplicitSelfBinding) = self_binding {
766 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf))
768 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
769 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
772 opt_match_place: Some((Some(place.clone()), span)),
776 self.var_indices.insert(var, LocalsForNode::One(local));
779 scope = self.declare_bindings(scope, ast_body.span,
780 LintLevel::Inherited, &[pattern.clone()],
781 matches::ArmHasGuard(false),
782 Some((Some(&place), span)));
783 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
788 // Make sure we drop (parts of) the argument even when not matched on.
790 pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
791 argument_scope, &place, ty,
792 DropKind::Value { cached_block: CachedBlock::default() },
796 // Enter the argument pattern bindings source scope, if it exists.
797 if let Some(source_scope) = scope {
798 self.source_scope = source_scope;
801 let body = self.hir.mirror(ast_body);
802 self.into(&Place::Local(RETURN_PLACE), block, body)
805 fn get_unit_temp(&mut self) -> Place<'tcx> {
806 match self.unit_temp {
807 Some(ref tmp) => tmp.clone(),
809 let ty = self.hir.unit_ty();
810 let fn_span = self.fn_span;
811 let tmp = self.temp(ty, fn_span);
812 self.unit_temp = Some(tmp.clone());
818 fn return_block(&mut self) -> BasicBlock {
819 match self.cached_return_block {
822 let rb = self.cfg.start_new_block();
823 self.cached_return_block = Some(rb);
829 fn unreachable_block(&mut self) -> BasicBlock {
830 match self.cached_unreachable_block {
833 let ub = self.cfg.start_new_block();
834 self.cached_unreachable_block = Some(ub);
841 ///////////////////////////////////////////////////////////////////////////
842 // Builder methods are broken up into modules, depending on what kind
843 // of thing is being lowered. Note that they use the `unpack` macro
844 // above extensively.