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::transform::MirSource;
20 use rustc::mir::visit::{MutVisitor, Lookup};
21 use rustc::ty::{self, Ty, TyCtxt};
22 use rustc::ty::subst::Substs;
23 use rustc::util::nodemap::NodeMap;
24 use rustc_const_eval::pattern::{BindingMode, PatternKind};
25 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
31 use syntax::symbol::keywords;
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 let src = MirSource::from_node(tcx, id);
87 tcx.infer_ctxt().enter(|infcx| {
88 let cx = Cx::new(&infcx, src);
89 let mut mir = if cx.tables().tainted_by_errors {
90 build::construct_error(cx, body_id)
91 } else if let MirSource::Fn(id) = src {
92 // fetch the fully liberated fn signature (that is, all bound
93 // types/lifetimes replaced)
94 let fn_hir_id = tcx.hir.node_to_hir_id(id);
95 let fn_sig = cx.tables().liberated_fn_sigs()[fn_hir_id].clone();
97 let ty = tcx.type_of(tcx.hir.local_def_id(id));
98 let mut abi = fn_sig.abi;
99 let implicit_argument = match ty.sty {
100 ty::TyClosure(..) => {
101 // HACK(eddyb) Avoid having RustCall on closures,
102 // as it adds unnecessary (and wrong) auto-tupling.
104 Some((closure_self_ty(tcx, id, body_id), None))
106 ty::TyGenerator(..) => {
107 let gen_ty = tcx.body_tables(body_id).node_id_to_type(fn_hir_id);
113 // FIXME: safety in closures
114 let safety = match fn_sig.unsafety {
115 hir::Unsafety::Normal => Safety::Safe,
116 hir::Unsafety::Unsafe => Safety::FnUnsafe,
119 let body = tcx.hir.body(body_id);
120 let explicit_arguments =
124 .map(|(index, arg)| {
125 (fn_sig.inputs()[index], Some(&*arg.pat))
128 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
130 let (yield_ty, return_ty) = if body.is_generator {
131 let gen_sig = cx.tables().generator_sigs()[fn_hir_id].clone().unwrap();
132 (Some(gen_sig.yield_ty), gen_sig.return_ty)
134 (None, fn_sig.output())
137 build::construct_fn(cx, id, arguments, safety, abi,
138 return_ty, yield_ty, body)
140 build::construct_const(cx, body_id)
143 // Convert the Mir to global types.
144 let mut globalizer = GlobalizeMir {
148 globalizer.visit_mir(&mut mir);
150 mem::transmute::<Mir, Mir<'tcx>>(mir)
153 mir_util::dump_mir(tcx, None, "mir_map", &0, src, &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>, _: Lookup) {
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| {
218 shim::build_adt_ctor(&infcx, ctor_id, fields, span);
220 // Convert the Mir to global types.
221 let tcx = infcx.tcx.global_tcx();
222 let mut globalizer = GlobalizeMir {
226 globalizer.visit_mir(&mut mir);
228 mem::transmute::<Mir, Mir<'tcx>>(mir)
231 mir_util::dump_mir(tcx, None, "mir_map", &0, src, &mir, |_, _| Ok(()) );
236 span_bug!(span, "attempting to create MIR for non-tuple variant {:?}", v);
240 ///////////////////////////////////////////////////////////////////////////
241 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
243 pub fn closure_self_ty<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
244 closure_expr_id: ast::NodeId,
245 body_id: hir::BodyId)
247 let closure_expr_hir_id = tcx.hir.node_to_hir_id(closure_expr_id);
248 let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_hir_id);
250 let closure_def_id = tcx.hir.local_def_id(closure_expr_id);
251 let region = ty::ReFree(ty::FreeRegion {
252 scope: closure_def_id,
253 bound_region: ty::BoundRegion::BrEnv,
255 let region = tcx.mk_region(region);
257 match tcx.closure_kind(closure_def_id) {
258 ty::ClosureKind::Fn =>
260 ty::TypeAndMut { ty: closure_ty,
261 mutbl: hir::MutImmutable }),
262 ty::ClosureKind::FnMut =>
264 ty::TypeAndMut { ty: closure_ty,
265 mutbl: hir::MutMutable }),
266 ty::ClosureKind::FnOnce =>
271 struct Builder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
272 hir: Cx<'a, 'gcx, 'tcx>,
278 /// the current set of scopes, updated as we traverse;
279 /// see the `scope` module for more details
280 scopes: Vec<scope::Scope<'tcx>>,
282 /// The current unsafe block in scope, even if it is hidden by
283 /// a PushUnsafeBlock
284 unpushed_unsafe: Safety,
286 /// The number of `push_unsafe_block` levels in scope
287 push_unsafe_count: usize,
289 /// the current set of breakables; see the `scope` module for more
291 breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
293 /// the vector of all scopes that we have created thus far;
294 /// we track this for debuginfo later
295 visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
296 visibility_scope_info: IndexVec<VisibilityScope, VisibilityScopeInfo>,
297 visibility_scope: VisibilityScope,
299 /// Maps node ids of variable bindings to the `Local`s created for them.
300 var_indices: NodeMap<Local>,
301 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
302 unit_temp: Option<Lvalue<'tcx>>,
304 /// cached block with the RESUME terminator; this is created
305 /// when first set of cleanups are built.
306 cached_resume_block: Option<BasicBlock>,
307 /// cached block with the RETURN terminator
308 cached_return_block: Option<BasicBlock>,
312 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
315 newtype_index!(ScopeId);
317 ///////////////////////////////////////////////////////////////////////////
318 /// The `BlockAnd` "monad" packages up the new basic block along with a
319 /// produced value (sometimes just unit, of course). The `unpack!`
320 /// macro (and methods below) makes working with `BlockAnd` much more
323 #[must_use] // if you don't use one of these results, you're leaving a dangling edge
324 struct BlockAnd<T>(BasicBlock, T);
326 trait BlockAndExtension {
327 fn and<T>(self, v: T) -> BlockAnd<T>;
328 fn unit(self) -> BlockAnd<()>;
331 impl BlockAndExtension for BasicBlock {
332 fn and<T>(self, v: T) -> BlockAnd<T> {
336 fn unit(self) -> BlockAnd<()> {
341 /// Update a block pointer and return the value.
342 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
343 macro_rules! unpack {
344 ($x:ident = $c:expr) => {
346 let BlockAnd(b, v) = $c;
354 let BlockAnd(b, ()) = $c;
360 ///////////////////////////////////////////////////////////////////////////
361 /// the main entry point for building MIR for a function
363 fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
369 yield_ty: Option<Ty<'gcx>>,
370 body: &'gcx hir::Body)
372 where A: Iterator<Item=(Ty<'gcx>, Option<&'gcx hir::Pat>)>
374 let arguments: Vec<_> = arguments.collect();
377 let span = tcx.hir.span(fn_id);
378 let mut builder = Builder::new(hir.clone(),
384 let call_site_scope = region::Scope::CallSite(body.value.hir_id.local_id);
385 let arg_scope = region::Scope::Arguments(body.value.hir_id.local_id);
386 let mut block = START_BLOCK;
387 let source_info = builder.source_info(span);
388 let call_site_s = (call_site_scope, source_info);
389 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
390 let arg_scope_s = (arg_scope, source_info);
391 unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
392 builder.args_and_body(block, &arguments, arg_scope, &body.value)
394 // Attribute epilogue to function's closing brace
395 let fn_end = span.with_lo(span.hi());
396 let source_info = builder.source_info(fn_end);
397 let return_block = builder.return_block();
398 builder.cfg.terminate(block, source_info,
399 TerminatorKind::Goto { target: return_block });
400 builder.cfg.terminate(return_block, source_info,
401 TerminatorKind::Return);
404 assert_eq!(block, builder.return_block());
406 let mut spread_arg = None;
407 if abi == Abi::RustCall {
408 // RustCall pseudo-ABI untuples the last argument.
409 spread_arg = Some(Local::new(arguments.len()));
412 // Gather the upvars of a closure, if any.
413 let upvar_decls: Vec<_> = tcx.with_freevars(fn_id, |freevars| {
414 freevars.iter().map(|fv| {
415 let var_id = fv.var_id();
416 let var_hir_id = tcx.hir.node_to_hir_id(var_id);
417 let closure_expr_id = tcx.hir.local_def_id(fn_id).index;
418 let capture = hir.tables().upvar_capture(ty::UpvarId {
422 let by_ref = match capture {
423 ty::UpvarCapture::ByValue => false,
424 ty::UpvarCapture::ByRef(..) => true
426 let mut decl = UpvarDecl {
427 debug_name: keywords::Invalid.name(),
430 if let Some(hir::map::NodeBinding(pat)) = tcx.hir.find(var_id) {
431 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
432 decl.debug_name = ident.node;
439 let mut mir = builder.finish(upvar_decls, return_ty, yield_ty);
440 mir.spread_arg = spread_arg;
444 fn construct_const<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
445 body_id: hir::BodyId)
448 let ast_expr = &tcx.hir.body(body_id).value;
449 let ty = hir.tables().expr_ty_adjusted(ast_expr);
450 let owner_id = tcx.hir.body_owner(body_id);
451 let span = tcx.hir.span(owner_id);
452 let mut builder = Builder::new(hir.clone(), span, 0, Safety::Safe, ty);
454 let mut block = START_BLOCK;
455 let expr = builder.hir.mirror(ast_expr);
456 unpack!(block = builder.into_expr(&Lvalue::Local(RETURN_POINTER), block, expr));
458 let source_info = builder.source_info(span);
459 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
461 // Constants can't `return` so a return block should not be created.
462 assert_eq!(builder.cached_return_block, None);
464 builder.finish(vec![], ty, None)
467 fn construct_error<'a, 'gcx, 'tcx>(hir: Cx<'a, 'gcx, 'tcx>,
468 body_id: hir::BodyId)
470 let owner_id = hir.tcx().hir.body_owner(body_id);
471 let span = hir.tcx().hir.span(owner_id);
472 let ty = hir.tcx().types.err;
473 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty);
474 let source_info = builder.source_info(span);
475 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
476 builder.finish(vec![], ty, None)
479 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
480 fn new(hir: Cx<'a, 'gcx, 'tcx>,
485 -> Builder<'a, 'gcx, 'tcx> {
486 let lint_level = LintLevel::Explicit(hir.root_lint_level);
487 let mut builder = Builder {
489 cfg: CFG { basic_blocks: IndexVec::new() },
493 visibility_scopes: IndexVec::new(),
494 visibility_scope: ARGUMENT_VISIBILITY_SCOPE,
495 visibility_scope_info: IndexVec::new(),
496 push_unsafe_count: 0,
497 unpushed_unsafe: safety,
498 breakable_scopes: vec![],
499 local_decls: IndexVec::from_elem_n(LocalDecl::new_return_pointer(return_ty,
501 var_indices: NodeMap(),
503 cached_resume_block: None,
504 cached_return_block: None
507 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
509 builder.new_visibility_scope(span, lint_level, Some(safety)),
510 ARGUMENT_VISIBILITY_SCOPE);
511 builder.visibility_scopes[ARGUMENT_VISIBILITY_SCOPE].parent_scope = None;
517 upvar_decls: Vec<UpvarDecl>,
519 yield_ty: Option<Ty<'tcx>>)
521 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
522 if block.terminator.is_none() {
523 span_bug!(self.fn_span, "no terminator on block {:?}", index);
527 Mir::new(self.cfg.basic_blocks,
528 self.visibility_scopes,
529 ClearOnDecode::Set(self.visibility_scope_info),
540 fn args_and_body(&mut self,
541 mut block: BasicBlock,
542 arguments: &[(Ty<'gcx>, Option<&'gcx hir::Pat>)],
543 argument_scope: region::Scope,
544 ast_body: &'gcx hir::Expr)
547 // Allocate locals for the function arguments
548 for &(ty, pattern) in arguments.iter() {
549 // If this is a simple binding pattern, give the local a nice name for debuginfo.
551 if let Some(pat) = pattern {
552 if let hir::PatKind::Binding(_, _, ref ident, _) = pat.node {
553 name = Some(ident.node);
557 self.local_decls.push(LocalDecl {
558 mutability: Mutability::Not,
560 source_info: SourceInfo {
561 scope: ARGUMENT_VISIBILITY_SCOPE,
562 span: pattern.map_or(self.fn_span, |pat| pat.span)
564 lexical_scope: ARGUMENT_VISIBILITY_SCOPE,
567 is_user_variable: false,
571 let mut scope = None;
572 // Bind the argument patterns
573 for (index, &(ty, pattern)) in arguments.iter().enumerate() {
574 // Function arguments always get the first Local indices after the return pointer
575 let local = Local::new(index + 1);
576 let lvalue = Lvalue::Local(local);
578 if let Some(pattern) = pattern {
579 let pattern = self.hir.pattern_from_hir(pattern);
581 match *pattern.kind {
582 // Don't introduce extra copies for simple bindings
583 PatternKind::Binding { mutability, var, mode: BindingMode::ByValue, .. } => {
584 self.local_decls[local].mutability = mutability;
585 self.var_indices.insert(var, local);
588 scope = self.declare_bindings(scope, ast_body.span,
589 LintLevel::Inherited, &pattern);
590 unpack!(block = self.lvalue_into_pattern(block, pattern, &lvalue));
595 // Make sure we drop (parts of) the argument even when not matched on.
596 self.schedule_drop(pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
597 argument_scope, &lvalue, ty);
601 // Enter the argument pattern bindings visibility scope, if it exists.
602 if let Some(visibility_scope) = scope {
603 self.visibility_scope = visibility_scope;
606 let body = self.hir.mirror(ast_body);
607 self.into(&Lvalue::Local(RETURN_POINTER), block, body)
610 fn get_unit_temp(&mut self) -> Lvalue<'tcx> {
611 match self.unit_temp {
612 Some(ref tmp) => tmp.clone(),
614 let ty = self.hir.unit_ty();
615 let fn_span = self.fn_span;
616 let tmp = self.temp(ty, fn_span);
617 self.unit_temp = Some(tmp.clone());
623 fn return_block(&mut self) -> BasicBlock {
624 match self.cached_return_block {
627 let rb = self.cfg.start_new_block();
628 self.cached_return_block = Some(rb);
635 ///////////////////////////////////////////////////////////////////////////
636 // Builder methods are broken up into modules, depending on what kind
637 // of thing is being translated. Note that they use the `unpack` macro
638 // above extensively.