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.
16 use rustc::hir::def_id::DefId;
17 use rustc::middle::region;
19 use rustc::mir::visit::{MutVisitor, TyContext};
20 use rustc::ty::{self, Ty, TyCtxt};
21 use rustc::ty::subst::Substs;
22 use rustc::util::nodemap::NodeMap;
23 use rustc_const_eval::pattern::{BindingMode, PatternKind};
24 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
30 use syntax::symbol::keywords;
32 use transform::MirSource;
35 /// Construct the MIR for a given def-id.
36 pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'tcx> {
37 let id = tcx.hir.as_local_node_id(def_id).unwrap();
38 let unsupported = || {
39 span_bug!(tcx.hir.span(id), "can't build MIR for {:?}", def_id);
42 // Figure out what primary body this item has.
43 let body_id = match tcx.hir.get(id) {
44 hir::map::NodeItem(item) => {
46 hir::ItemConst(_, body) |
47 hir::ItemStatic(_, _, body) |
48 hir::ItemFn(.., body) => body,
52 hir::map::NodeTraitItem(item) => {
54 hir::TraitItemKind::Const(_, Some(body)) |
55 hir::TraitItemKind::Method(_,
56 hir::TraitMethod::Provided(body)) => body,
60 hir::map::NodeImplItem(item) => {
62 hir::ImplItemKind::Const(_, body) |
63 hir::ImplItemKind::Method(_, body) => body,
67 hir::map::NodeExpr(expr) => {
68 // FIXME(eddyb) Closures should have separate
69 // function definition IDs and expression IDs.
70 // Type-checking should not let closures get
71 // this far in a constant position.
72 // Assume that everything other than closures
73 // is a constant "initializer" expression.
75 hir::ExprClosure(_, _, body, _, _) => body,
76 _ => hir::BodyId { node_id: expr.id },
79 hir::map::NodeVariant(variant) =>
80 return create_constructor_shim(tcx, id, &variant.node.data),
81 hir::map::NodeStructCtor(ctor) =>
82 return create_constructor_shim(tcx, id, ctor),
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();
96 let ty = tcx.type_of(tcx.hir.local_def_id(id));
97 let mut abi = fn_sig.abi;
98 let implicit_argument = match ty.sty {
99 ty::TyClosure(..) => {
100 // HACK(eddyb) Avoid having RustCall on closures,
101 // as it adds unnecessary (and wrong) auto-tupling.
103 Some((closure_self_ty(tcx, id, body_id), None))
105 ty::TyGenerator(..) => {
106 let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
112 // FIXME: safety in closures
113 let safety = match fn_sig.unsafety {
114 hir::Unsafety::Normal => Safety::Safe,
115 hir::Unsafety::Unsafe => Safety::FnUnsafe,
118 let body = tcx.hir.body(body_id);
119 let explicit_arguments =
123 .map(|(index, arg)| {
124 (fn_sig.inputs()[index], Some(&*arg.pat))
127 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
129 let (yield_ty, return_ty) = if body.is_generator {
130 let gen_sig = cx.tables().generator_sigs()[fn_hir_id].clone().unwrap();
131 (Some(gen_sig.yield_ty), gen_sig.return_ty)
133 (None, fn_sig.output())
136 build::construct_fn(cx, id, arguments, safety, abi,
137 return_ty, yield_ty, body)
139 build::construct_const(cx, body_id)
142 // Convert the Mir to global types.
143 let mut globalizer = GlobalizeMir {
147 globalizer.visit_mir(&mut mir);
149 mem::transmute::<Mir, Mir<'tcx>>(mir)
152 mir_util::dump_mir(tcx, None, "mir_map", &0,
153 MirSource::item(def_id), &mir, |_, _| Ok(()) );
159 /// A pass to lift all the types and substitutions in a Mir
160 /// to the global tcx. Sadly, we don't have a "folder" that
161 /// can change 'tcx so we have to transmute afterwards.
162 struct GlobalizeMir<'a, 'gcx: 'a> {
163 tcx: TyCtxt<'a, 'gcx, 'gcx>,
167 impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
168 fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
169 if let Some(lifted) = self.tcx.lift(ty) {
173 "found type `{:?}` with inference types/regions in MIR",
178 fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
179 if let Some(lifted) = self.tcx.lift(region) {
183 "found region `{:?}` with inference types/regions in MIR",
188 fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
189 if let Some(lifted) = self.tcx.lift(constant) {
193 "found constant `{:?}` with inference types/regions in MIR",
198 fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
199 if let Some(lifted) = self.tcx.lift(substs) {
203 "found substs `{:?}` with inference types/regions in MIR",
209 fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
210 ctor_id: ast::NodeId,
211 v: &'tcx hir::VariantData)
214 let span = tcx.hir.span(ctor_id);
215 if let hir::VariantData::Tuple(ref fields, ctor_id) = *v {
216 tcx.infer_ctxt().enter(|infcx| {
217 let mut mir = shim::build_adt_ctor(&infcx, ctor_id, fields, span);
219 // Convert the Mir to global types.
220 let tcx = infcx.tcx.global_tcx();
221 let mut globalizer = GlobalizeMir {
225 globalizer.visit_mir(&mut mir);
227 mem::transmute::<Mir, Mir<'tcx>>(mir)
230 mir_util::dump_mir(tcx, None, "mir_map", &0,
231 MirSource::item(tcx.hir.local_def_id(ctor_id)),
232 &mir, |_, _| Ok(()) );
237 span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v);
241 ///////////////////////////////////////////////////////////////////////////
242 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
244 pub fn closure_self_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
245 closure_expr_id: ast::NodeId,
246 body_id: hir::BodyId)
248 let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id);
249 let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id);
251 let closure_def_id = tcx.hir.local_def_id(closure_expr_id);
252 let region = ty::ReFree(ty::FreeRegion {
253 scope: closure_def_id,
254 bound_region: ty::BoundRegion::BrEnv,
256 let region = tcx.mk_region(region);
258 match tcx.closure_kind(closure_def_id) {
259 ty::ClosureKind::Fn =>
261 ty::TypeAndMut { ty: closure_ty,
262 mutbl: hir::MutImmutable }),
263 ty::ClosureKind::FnMut =>
265 ty::TypeAndMut { ty: closure_ty,
266 mutbl: hir::MutMutable }),
267 ty::ClosureKind::FnOnce =>
272 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
273 hir: Cx<'a, 'gcx, 'tcx>,
279 /// the current set of scopes, updated as we traverse;
280 /// see the `scope` module for more details
281 scopes: Vec<scope::Scope<'tcx>>,
283 /// The current unsafe block in scope, even if it is hidden by
284 /// a PushUnsafeBlock
285 unpushed_unsafe: Safety,
287 /// The number of `push_unsafe_block` levels in scope
288 push_unsafe_count: usize,
290 /// the current set of breakables; see the `scope` module for more
292 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
294 /// the vector of all scopes that we have created thus far;
295 /// we track this for debuginfo later
296 visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
297 visibility_scope_info: IndexVec<VisibilityScope, VisibilityScopeInfo>,
298 visibility_scope: VisibilityScope,
300 /// Maps node ids of variable bindings to the `Local`s created for them.
301 var_indices: NodeMap<Local>,
302 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
303 unit_temp: Option<Lvalue<'tcx>>,
305 /// cached block with the RESUME terminator; this is created
306 /// when first set of cleanups are built.
307 cached_resume_block: Option<BasicBlock>,
308 /// cached block with the RETURN terminator
309 cached_return_block: Option<BasicBlock>,
313 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
316 newtype_index!(ScopeId);
318 ///////////////////////////////////////////////////////////////////////////
319 /// The `BlockAnd` "monad" packages up the new basic block along with a
320 /// produced value (sometimes just unit, of course). The `unpack!`
321 /// macro (and methods below) makes working with `BlockAnd` much more
324 #[must_use] // if you don't use one of these results, you're leaving a dangling edge
325 struct BlockAnd<T>(BasicBlock, T);
327 trait BlockAndExtension {
328 fn and<T>(self, v: T) -> BlockAnd<T>;
329 fn unit(self) -> BlockAnd<()>;
332 impl BlockAndExtension for BasicBlock {
333 fn and<T>(self, v: T) -> BlockAnd<T> {
337 fn unit(self) -> BlockAnd<()> {
342 /// Update a block pointer and return the value.
343 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
344 macro_rules! unpack {
345 ($x:ident = $c:expr) => {
347 let BlockAnd(b, v) = $c;
355 let BlockAnd(b, ()) = $c;
361 ///////////////////////////////////////////////////////////////////////////
362 /// the main entry point for building MIR for a function
364 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
370 yield_ty: Option<Ty<'gcx>>,
371 body: &'gcx hir::Body)
373 where A: Iterator<Item=(Ty<'gcx>, Option<&'gcx hir::Pat>)>
375 let arguments: Vec<_> = arguments.collect();
378 let span = tcx.hir.span(fn_id);
379 let mut builder = Builder::new(hir.clone(),
385 let call_site_scope = region::Scope::CallSite(body.value.hir_id.local_id);
386 let arg_scope = region::Scope::Arguments(body.value.hir_id.local_id);
387 let mut block = START_BLOCK;
388 let source_info = builder.source_info(span);
389 let call_site_s = (call_site_scope, source_info);
390 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
391 let arg_scope_s = (arg_scope, source_info);
392 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
393 builder.args_and_body(block, &arguments, arg_scope, &body.value)
395 // Attribute epilogue to function's closing brace
396 let fn_end = span.with_lo(span.hi());
397 let source_info = builder.source_info(fn_end);
398 let return_block = builder.return_block();
399 builder.cfg.terminate(block, source_info,
400 TerminatorKind::Goto { target: return_block });
401 builder.cfg.terminate(return_block, source_info,
402 TerminatorKind::Return);
405 assert_eq!(block, builder.return_block());
407 let mut spread_arg = None;
408 if abi == Abi::RustCall {
409 // RustCall pseudo-ABI untuples the last argument.
410 spread_arg = Some(Local::new(arguments.len()));
413 // Gather the upvars of a closure, if any.
414 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
415 freevars.iter().map(|fv| {
416 let var_id = fv.var_id();
417 let var_hir_id = tcx.hir.node_to_hir_id(var_id);
418 let closure_expr_id = tcx.hir.local_def_id(fn_id).index;
419 let capture = hir.tables().upvar_capture(ty::UpvarId {
423 let by_ref = match capture {
424 ty::UpvarCapture::ByValue => false,
425 ty::UpvarCapture::ByRef(..) => true
427 let mut decl = UpvarDecl {
428 debug_name: keywords::Invalid.name(),
431 if let Some(hir::map::NodeBinding(pat)) = tcx.hir.find(var_id) {
432 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
433 decl.debug_name = ident.node;
440 let mut mir = builder.finish(upvar_decls, return_ty, yield_ty);
441 mir.spread_arg = spread_arg;
445 fn construct_const<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
446 body_id: hir::BodyId)
449 let ast_expr = &tcx.hir.body(body_id).value;
450 let ty = hir.tables().expr_ty_adjusted(ast_expr);
451 let owner_id = tcx.hir.body_owner(body_id);
452 let span = tcx.hir.span(owner_id);
453 let mut builder = Builder::new(hir.clone(), span, 0, Safety::Safe, ty);
455 let mut block = START_BLOCK;
456 let expr = builder.hir.mirror(ast_expr);
457 unpack!(block = builder.into_expr(&Lvalue::Local(RETURN_POINTER), block, expr));
459 let source_info = builder.source_info(span);
460 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
462 // Constants can't `return` so a return block should not be created.
463 assert_eq!(builder.cached_return_block, None);
465 builder.finish(vec![], ty, None)
468 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
469 body_id: hir::BodyId)
471 let owner_id = hir.tcx().hir.body_owner(body_id);
472 let span = hir.tcx().hir.span(owner_id);
473 let ty = hir.tcx().types.err;
474 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty);
475 let source_info = builder.source_info(span);
476 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
477 builder.finish(vec![], ty, None)
480 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
481 fn new(hir: Cx<'a, 'gcx, 'tcx>,
486 -> Builder<'a, 'gcx, 'tcx> {
487 let lint_level = LintLevel::Explicit(hir.root_lint_level);
488 let mut builder = Builder {
490 cfg: CFG { basic_blocks: IndexVec::new() },
494 visibility_scopes: IndexVec::new(),
495 visibility_scope: ARGUMENT_VISIBILITY_SCOPE,
496 visibility_scope_info: IndexVec::new(),
497 push_unsafe_count: 0,
498 unpushed_unsafe: safety,
499 breakable_scopes: vec![],
500 local_decls: IndexVec::from_elem_n(LocalDecl::new_return_pointer(return_ty,
502 var_indices: NodeMap(),
504 cached_resume_block: None,
505 cached_return_block: None
508 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
510 builder.new_visibility_scope(span, lint_level, Some(safety)),
511 ARGUMENT_VISIBILITY_SCOPE);
512 builder.visibility_scopes[ARGUMENT_VISIBILITY_SCOPE].parent_scope = None;
518 upvar_decls: Vec<UpvarDecl>,
520 yield_ty: Option<Ty<'tcx>>)
522 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
523 if block.terminator.is_none() {
524 span_bug!(self.fn_span, "no terminator on block {:?}", index);
528 Mir::new(self.cfg.basic_blocks,
529 self.visibility_scopes,
530 ClearOnDecode::Set(self.visibility_scope_info),
541 fn args_and_body(&mut self,
542 mut block: BasicBlock,
543 arguments: &[(Ty<'gcx>, Option<&'gcx hir::Pat>)],
544 argument_scope: region::Scope,
545 ast_body: &'gcx hir::Expr)
548 // Allocate locals for the function arguments
549 for &(ty, pattern) in arguments.iter() {
550 // If this is a simple binding pattern, give the local a nice name for debuginfo.
552 if let Some(pat) = pattern {
553 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
554 name = Some(ident.node);
558 self.local_decls.push(LocalDecl {
559 mutability: Mutability::Not,
561 source_info: SourceInfo {
562 scope: ARGUMENT_VISIBILITY_SCOPE,
563 span: pattern.map_or(self.fn_span, |pat| pat.span)
565 lexical_scope: ARGUMENT_VISIBILITY_SCOPE,
568 is_user_variable: false,
572 let mut scope = None;
573 // Bind the argument patterns
574 for (index, &(ty, pattern)) in arguments.iter().enumerate() {
575 // Function arguments always get the first Local indices after the return pointer
576 let local = Local::new(index + 1);
577 let lvalue = Lvalue::Local(local);
579 if let Some(pattern) = pattern {
580 let pattern = self.hir.pattern_from_hir(pattern);
582 match *pattern.kind {
583 // Don't introduce extra copies for simple bindings
584 PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
585 self.local_decls[local].mutability = mutability;
586 self.var_indices.insert(var, local);
589 scope = self.declare_bindings(scope, ast_body.span,
590 LintLevel::Inherited, &pattern);
591 unpack!(block = self.lvalue_into_pattern(block, pattern, &lvalue));
596 // Make sure we drop (parts of) the argument even when not matched on.
597 self.schedule_drop(pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
598 argument_scope, &lvalue, ty);
602 // Enter the argument pattern bindings visibility scope, if it exists.
603 if let Some(visibility_scope) = scope {
604 self.visibility_scope = visibility_scope;
607 let body = self.hir.mirror(ast_body);
608 self.into(&Lvalue::Local(RETURN_POINTER), block, body)
611 fn get_unit_temp(&mut self) -> Lvalue<'tcx> {
612 match self.unit_temp {
613 Some(ref tmp) => tmp.clone(),
615 let ty = self.hir.unit_ty();
616 let fn_span = self.fn_span;
617 let tmp = self.temp(ty, fn_span);
618 self.unit_temp = Some(tmp.clone());
624 fn return_block(&mut self) -> BasicBlock {
625 match self.cached_return_block {
628 let rb = self.cfg.start_new_block();
629 self.cached_return_block = Some(rb);
636 ///////////////////////////////////////////////////////////////////////////
637 // Builder methods are broken up into modules, depending on what kind
638 // of thing is being translated. Note that they use the `unpack` macro
639 // above extensively.