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Diffstat (limited to 'compiler/rustc_mir_build/src/build/mod.rs')
| -rw-r--r-- | compiler/rustc_mir_build/src/build/mod.rs | 1030 |
1 files changed, 1030 insertions, 0 deletions
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs new file mode 100644 index 00000000000..249cce0ba19 --- /dev/null +++ b/compiler/rustc_mir_build/src/build/mod.rs @@ -0,0 +1,1030 @@ +use crate::build; +use crate::build::scope::DropKind; +use crate::thir::cx::Cx; +use crate::thir::{BindingMode, LintLevel, PatKind}; +use rustc_attr::{self as attr, UnwindAttr}; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{GeneratorKind, HirIdMap, Node}; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_infer::infer::TyCtxtInferExt; +use rustc_middle::middle::region; +use rustc_middle::mir::*; +use rustc_middle::ty::subst::Subst; +use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable}; +use rustc_span::symbol::kw; +use rustc_span::Span; +use rustc_target::spec::abi::Abi; +use rustc_target::spec::PanicStrategy; + +use super::lints; + +crate fn mir_built<'tcx>( + tcx: TyCtxt<'tcx>, + def: ty::WithOptConstParam<LocalDefId>, +) -> &'tcx ty::steal::Steal<Body<'tcx>> { + if let Some(def) = def.try_upgrade(tcx) { + return tcx.mir_built(def); + } + + tcx.alloc_steal_mir(mir_build(tcx, def)) +} + +/// Construct the MIR for a given `DefId`. +fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> { + let id = tcx.hir().local_def_id_to_hir_id(def.did); + + // Figure out what primary body this item has. + let (body_id, return_ty_span, span_with_body) = match tcx.hir().get(id) { + Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. }) => { + (*body_id, decl.output.span(), None) + } + Node::Item(hir::Item { + kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id), + span, + .. + }) + | Node::ImplItem(hir::ImplItem { + kind: hir::ImplItemKind::Fn(hir::FnSig { decl, .. }, body_id), + span, + .. + }) + | Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(hir::FnSig { decl, .. }, hir::TraitFn::Provided(body_id)), + span, + .. + }) => { + // Use the `Span` of the `Item/ImplItem/TraitItem` as the body span, + // since the def span of a function does not include the body + (*body_id, decl.output.span(), Some(*span)) + } + Node::Item(hir::Item { + kind: hir::ItemKind::Static(ty, _, body_id) | hir::ItemKind::Const(ty, body_id), + .. + }) + | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. }) + | Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Const(ty, Some(body_id)), + .. + }) => (*body_id, ty.span, None), + Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => (*body, tcx.hir().span(*hir_id), None), + + _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def.did), + }; + + // If we don't have a specialized span for the body, just use the + // normal def span. + let span_with_body = span_with_body.unwrap_or_else(|| tcx.hir().span(id)); + + tcx.infer_ctxt().enter(|infcx| { + let cx = Cx::new(&infcx, def, id); + let body = if let Some(ErrorReported) = cx.typeck_results().tainted_by_errors { + build::construct_error(cx, body_id) + } else if cx.body_owner_kind.is_fn_or_closure() { + // fetch the fully liberated fn signature (that is, all bound + // types/lifetimes replaced) + let fn_sig = cx.typeck_results().liberated_fn_sigs()[id]; + let fn_def_id = tcx.hir().local_def_id(id); + + let safety = match fn_sig.unsafety { + hir::Unsafety::Normal => Safety::Safe, + hir::Unsafety::Unsafe => Safety::FnUnsafe, + }; + + let body = tcx.hir().body(body_id); + let ty = tcx.type_of(fn_def_id); + let mut abi = fn_sig.abi; + let implicit_argument = match ty.kind { + ty::Closure(..) => { + // HACK(eddyb) Avoid having RustCall on closures, + // as it adds unnecessary (and wrong) auto-tupling. + abi = Abi::Rust; + vec![ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None)] + } + ty::Generator(..) => { + let gen_ty = tcx.typeck_body(body_id).node_type(id); + + // The resume argument may be missing, in that case we need to provide it here. + // It will always be `()` in this case. + if body.params.is_empty() { + vec![ + ArgInfo(gen_ty, None, None, None), + ArgInfo(tcx.mk_unit(), None, None, None), + ] + } else { + vec![ArgInfo(gen_ty, None, None, None)] + } + } + _ => vec![], + }; + + let explicit_arguments = body.params.iter().enumerate().map(|(index, arg)| { + let owner_id = tcx.hir().body_owner(body_id); + let opt_ty_info; + let self_arg; + if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) { + opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span); + self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() { + match fn_decl.implicit_self { + hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm), + hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut), + hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef), + hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef), + _ => None, + } + } else { + None + }; + } else { + opt_ty_info = None; + self_arg = None; + } + + // C-variadic fns also have a `VaList` input that's not listed in `fn_sig` + // (as it's created inside the body itself, not passed in from outside). + let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() { + let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(arg.span)); + + tcx.type_of(va_list_did).subst(tcx, &[tcx.lifetimes.re_erased.into()]) + } else { + fn_sig.inputs()[index] + }; + + ArgInfo(ty, opt_ty_info, Some(&arg), self_arg) + }); + + let arguments = implicit_argument.into_iter().chain(explicit_arguments); + + let (yield_ty, return_ty) = if body.generator_kind.is_some() { + let gen_ty = tcx.typeck_body(body_id).node_type(id); + let gen_sig = match gen_ty.kind { + ty::Generator(_, gen_substs, ..) => gen_substs.as_generator().sig(), + _ => span_bug!(tcx.hir().span(id), "generator w/o generator type: {:?}", ty), + }; + (Some(gen_sig.yield_ty), gen_sig.return_ty) + } else { + (None, fn_sig.output()) + }; + + let mut mir = build::construct_fn( + cx, + id, + arguments, + safety, + abi, + return_ty, + return_ty_span, + body, + span_with_body + ); + mir.yield_ty = yield_ty; + mir + } else { + // Get the revealed type of this const. This is *not* the adjusted + // type of its body, which may be a subtype of this type. For + // example: + // + // fn foo(_: &()) {} + // static X: fn(&'static ()) = foo; + // + // The adjusted type of the body of X is `for<'a> fn(&'a ())` which + // is not the same as the type of X. We need the type of the return + // place to be the type of the constant because NLL typeck will + // equate them. + + let return_ty = cx.typeck_results().node_type(id); + + build::construct_const(cx, body_id, return_ty, return_ty_span) + }; + + lints::check(tcx, &body, def.did); + + // The borrow checker will replace all the regions here with its own + // inference variables. There's no point having non-erased regions here. + // The exception is `body.user_type_annotations`, which is used unmodified + // by borrow checking. + debug_assert!( + !(body.local_decls.has_free_regions() + || body.basic_blocks().has_free_regions() + || body.var_debug_info.has_free_regions() + || body.yield_ty.has_free_regions()), + "Unexpected free regions in MIR: {:?}", + body, + ); + + body + }) +} + +/////////////////////////////////////////////////////////////////////////// +// BuildMir -- walks a crate, looking for fn items and methods to build MIR from + +fn liberated_closure_env_ty( + tcx: TyCtxt<'_>, + closure_expr_id: hir::HirId, + body_id: hir::BodyId, +) -> Ty<'_> { + let closure_ty = tcx.typeck_body(body_id).node_type(closure_expr_id); + + let (closure_def_id, closure_substs) = match closure_ty.kind { + ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs), + _ => bug!("closure expr does not have closure type: {:?}", closure_ty), + }; + + let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap(); + tcx.erase_late_bound_regions(&closure_env_ty) +} + +#[derive(Debug, PartialEq, Eq)] +enum BlockFrame { + /// Evaluation is currently within a statement. + /// + /// Examples include: + /// 1. `EXPR;` + /// 2. `let _ = EXPR;` + /// 3. `let x = EXPR;` + Statement { + /// If true, then statement discards result from evaluating + /// the expression (such as examples 1 and 2 above). + ignores_expr_result: bool, + }, + + /// Evaluation is currently within the tail expression of a block. + /// + /// Example: `{ STMT_1; STMT_2; EXPR }` + TailExpr { + /// If true, then the surrounding context of the block ignores + /// the result of evaluating the block's tail expression. + /// + /// Example: `let _ = { STMT_1; EXPR };` + tail_result_is_ignored: bool, + + /// `Span` of the tail expression. + span: Span, + }, + + /// Generic mark meaning that the block occurred as a subexpression + /// where the result might be used. + /// + /// Examples: `foo(EXPR)`, `match EXPR { ... }` + SubExpr, +} + +impl BlockFrame { + fn is_tail_expr(&self) -> bool { + match *self { + BlockFrame::TailExpr { .. } => true, + + BlockFrame::Statement { .. } | BlockFrame::SubExpr => false, + } + } + fn is_statement(&self) -> bool { + match *self { + BlockFrame::Statement { .. } => true, + + BlockFrame::TailExpr { .. } | BlockFrame::SubExpr => false, + } + } +} + +#[derive(Debug)] +struct BlockContext(Vec<BlockFrame>); + +struct Builder<'a, 'tcx> { + hir: Cx<'a, 'tcx>, + cfg: CFG<'tcx>, + + fn_span: Span, + arg_count: usize, + generator_kind: Option<GeneratorKind>, + + /// The current set of scopes, updated as we traverse; + /// see the `scope` module for more details. + scopes: scope::Scopes<'tcx>, + + /// The block-context: each time we build the code within an thir::Block, + /// we push a frame here tracking whether we are building a statement or + /// if we are pushing the tail expression of the block. This is used to + /// embed information in generated temps about whether they were created + /// for a block tail expression or not. + /// + /// It would be great if we could fold this into `self.scopes` + /// somehow, but right now I think that is very tightly tied to + /// the code generation in ways that we cannot (or should not) + /// start just throwing new entries onto that vector in order to + /// distinguish the context of EXPR1 from the context of EXPR2 in + /// `{ STMTS; EXPR1 } + EXPR2`. + block_context: BlockContext, + + /// The current unsafe block in scope, even if it is hidden by + /// a `PushUnsafeBlock`. + unpushed_unsafe: Safety, + + /// The number of `push_unsafe_block` levels in scope. + push_unsafe_count: usize, + + /// The vector of all scopes that we have created thus far; + /// we track this for debuginfo later. + source_scopes: IndexVec<SourceScope, SourceScopeData>, + source_scope: SourceScope, + + /// The guard-context: each time we build the guard expression for + /// a match arm, we push onto this stack, and then pop when we + /// finish building it. + guard_context: Vec<GuardFrame>, + + /// Maps `HirId`s of variable bindings to the `Local`s created for them. + /// (A match binding can have two locals; the 2nd is for the arm's guard.) + var_indices: HirIdMap<LocalsForNode>, + local_decls: IndexVec<Local, LocalDecl<'tcx>>, + canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>, + upvar_mutbls: Vec<Mutability>, + unit_temp: Option<Place<'tcx>>, + + var_debug_info: Vec<VarDebugInfo<'tcx>>, + + /// Cached block with the `RESUME` terminator; this is created + /// when first set of cleanups are built. + cached_resume_block: Option<BasicBlock>, + /// Cached block with the `RETURN` terminator. + cached_return_block: Option<BasicBlock>, + /// Cached block with the `UNREACHABLE` terminator. + cached_unreachable_block: Option<BasicBlock>, +} + +impl<'a, 'tcx> Builder<'a, 'tcx> { + fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool { + self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id)) + } + + fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local { + self.var_indices[&id].local_id(for_guard) + } +} + +impl BlockContext { + fn new() -> Self { + BlockContext(vec![]) + } + fn push(&mut self, bf: BlockFrame) { + self.0.push(bf); + } + fn pop(&mut self) -> Option<BlockFrame> { + self.0.pop() + } + + /// Traverses the frames on the `BlockContext`, searching for either + /// the first block-tail expression frame with no intervening + /// statement frame. + /// + /// Notably, this skips over `SubExpr` frames; this method is + /// meant to be used in the context of understanding the + /// relationship of a temp (created within some complicated + /// expression) with its containing expression, and whether the + /// value of that *containing expression* (not the temp!) is + /// ignored. + fn currently_in_block_tail(&self) -> Option<BlockTailInfo> { + for bf in self.0.iter().rev() { + match bf { + BlockFrame::SubExpr => continue, + BlockFrame::Statement { .. } => break, + &BlockFrame::TailExpr { tail_result_is_ignored, span } => { + return Some(BlockTailInfo { tail_result_is_ignored, span }); + } + } + } + + None + } + + /// Looks at the topmost frame on the BlockContext and reports + /// whether its one that would discard a block tail result. + /// + /// Unlike `currently_within_ignored_tail_expression`, this does + /// *not* skip over `SubExpr` frames: here, we want to know + /// whether the block result itself is discarded. + fn currently_ignores_tail_results(&self) -> bool { + match self.0.last() { + // no context: conservatively assume result is read + None => false, + + // sub-expression: block result feeds into some computation + Some(BlockFrame::SubExpr) => false, + + // otherwise: use accumulated is_ignored state. + Some( + BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. } + | BlockFrame::Statement { ignores_expr_result: ignored }, + ) => *ignored, + } + } +} + +#[derive(Debug)] +enum LocalsForNode { + /// In the usual case, a `HirId` for an identifier maps to at most + /// one `Local` declaration. + One(Local), + + /// The exceptional case is identifiers in a match arm's pattern + /// that are referenced in a guard of that match arm. For these, + /// we have `2` Locals. + /// + /// * `for_arm_body` is the Local used in the arm body (which is + /// just like the `One` case above), + /// + /// * `ref_for_guard` is the Local used in the arm's guard (which + /// is a reference to a temp that is an alias of + /// `for_arm_body`). + ForGuard { ref_for_guard: Local, for_arm_body: Local }, +} + +#[derive(Debug)] +struct GuardFrameLocal { + id: hir::HirId, +} + +impl GuardFrameLocal { + fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self { + GuardFrameLocal { id } + } +} + +#[derive(Debug)] +struct GuardFrame { + /// These are the id's of names that are bound by patterns of the + /// arm of *this* guard. + /// + /// (Frames higher up the stack will have the id's bound in arms + /// further out, such as in a case like: + /// + /// match E1 { + /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1, + /// } + /// + /// here, when building for FIXME. + locals: Vec<GuardFrameLocal>, +} + +/// `ForGuard` indicates whether we are talking about: +/// 1. The variable for use outside of guard expressions, or +/// 2. The temp that holds reference to (1.), which is actually what the +/// guard expressions see. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +enum ForGuard { + RefWithinGuard, + OutsideGuard, +} + +impl LocalsForNode { + fn local_id(&self, for_guard: ForGuard) -> Local { + match (self, for_guard) { + (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) + | ( + &LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, + ForGuard::RefWithinGuard, + ) + | (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) => { + local_id + } + + (&LocalsForNode::One(_), ForGuard::RefWithinGuard) => { + bug!("anything with one local should never be within a guard.") + } + } + } +} + +struct CFG<'tcx> { + basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, +} + +rustc_index::newtype_index! { + struct ScopeId { .. } +} + +/////////////////////////////////////////////////////////////////////////// +/// The `BlockAnd` "monad" packages up the new basic block along with a +/// produced value (sometimes just unit, of course). The `unpack!` +/// macro (and methods below) makes working with `BlockAnd` much more +/// convenient. + +#[must_use = "if you don't use one of these results, you're leaving a dangling edge"] +struct BlockAnd<T>(BasicBlock, T); + +trait BlockAndExtension { + fn and<T>(self, v: T) -> BlockAnd<T>; + fn unit(self) -> BlockAnd<()>; +} + +impl BlockAndExtension for BasicBlock { + fn and<T>(self, v: T) -> BlockAnd<T> { + BlockAnd(self, v) + } + + fn unit(self) -> BlockAnd<()> { + BlockAnd(self, ()) + } +} + +/// Update a block pointer and return the value. +/// Use it like `let x = unpack!(block = self.foo(block, foo))`. +macro_rules! unpack { + ($x:ident = $c:expr) => {{ + let BlockAnd(b, v) = $c; + $x = b; + v + }}; + + ($c:expr) => {{ + let BlockAnd(b, ()) = $c; + b + }}; +} + +fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: LocalDefId, _abi: Abi) -> bool { + // Validate `#[unwind]` syntax regardless of platform-specific panic strategy. + let attrs = &tcx.get_attrs(fn_def_id.to_def_id()); + let unwind_attr = attr::find_unwind_attr(&tcx.sess, attrs); + + // We never unwind, so it's not relevant to stop an unwind. + if tcx.sess.panic_strategy() != PanicStrategy::Unwind { + return false; + } + + // This is a special case: some functions have a C abi but are meant to + // unwind anyway. Don't stop them. + match unwind_attr { + None => false, // FIXME(#58794); should be `!(abi == Abi::Rust || abi == Abi::RustCall)` + Some(UnwindAttr::Allowed) => false, + Some(UnwindAttr::Aborts) => true, + } +} + +/////////////////////////////////////////////////////////////////////////// +/// the main entry point for building MIR for a function + +struct ArgInfo<'tcx>( + Ty<'tcx>, + Option<Span>, + Option<&'tcx hir::Param<'tcx>>, + Option<ImplicitSelfKind>, +); + +fn construct_fn<'a, 'tcx, A>( + hir: Cx<'a, 'tcx>, + fn_id: hir::HirId, + arguments: A, + safety: Safety, + abi: Abi, + return_ty: Ty<'tcx>, + return_ty_span: Span, + body: &'tcx hir::Body<'tcx>, + span_with_body: Span +) -> Body<'tcx> +where + A: Iterator<Item = ArgInfo<'tcx>>, +{ + let arguments: Vec<_> = arguments.collect(); + + let tcx = hir.tcx(); + let tcx_hir = tcx.hir(); + let span = tcx_hir.span(fn_id); + + let fn_def_id = tcx_hir.local_def_id(fn_id); + + let mut builder = Builder::new( + hir, + span_with_body, + arguments.len(), + safety, + return_ty, + return_ty_span, + body.generator_kind, + ); + + let call_site_scope = + region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::CallSite }; + let arg_scope = + region::Scope { id: body.value.hir_id.local_id, data: region::ScopeData::Arguments }; + let mut block = START_BLOCK; + let source_info = builder.source_info(span); + let call_site_s = (call_site_scope, source_info); + unpack!( + block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| { + if should_abort_on_panic(tcx, fn_def_id, abi) { + builder.schedule_abort(); + } + + let arg_scope_s = (arg_scope, source_info); + // `return_block` is called when we evaluate a `return` expression, so + // we just use `START_BLOCK` here. + unpack!( + block = builder.in_breakable_scope( + None, + START_BLOCK, + Place::return_place(), + |builder| { + builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| { + builder.args_and_body( + block, + fn_def_id.to_def_id(), + &arguments, + arg_scope, + &body.value, + ) + }) + }, + ) + ); + // Attribute epilogue to function's closing brace + let fn_end = span_with_body.shrink_to_hi(); + let source_info = builder.source_info(fn_end); + let return_block = builder.return_block(); + builder.cfg.goto(block, source_info, return_block); + builder.cfg.terminate(return_block, source_info, TerminatorKind::Return); + // Attribute any unreachable codepaths to the function's closing brace + if let Some(unreachable_block) = builder.cached_unreachable_block { + builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable); + } + return_block.unit() + }) + ); + assert_eq!(block, builder.return_block()); + + let spread_arg = if abi == Abi::RustCall { + // RustCall pseudo-ABI untuples the last argument. + Some(Local::new(arguments.len())) + } else { + None + }; + debug!("fn_id {:?} has attrs {:?}", fn_def_id, tcx.get_attrs(fn_def_id.to_def_id())); + + let mut body = builder.finish(); + body.spread_arg = spread_arg; + body +} + +fn construct_const<'a, 'tcx>( + hir: Cx<'a, 'tcx>, + body_id: hir::BodyId, + const_ty: Ty<'tcx>, + const_ty_span: Span, +) -> Body<'tcx> { + let tcx = hir.tcx(); + let owner_id = tcx.hir().body_owner(body_id); + let span = tcx.hir().span(owner_id); + let mut builder = Builder::new(hir, span, 0, Safety::Safe, const_ty, const_ty_span, None); + + let mut block = START_BLOCK; + let ast_expr = &tcx.hir().body(body_id).value; + let expr = builder.hir.mirror(ast_expr); + unpack!(block = builder.into_expr(Place::return_place(), block, expr)); + + let source_info = builder.source_info(span); + builder.cfg.terminate(block, source_info, TerminatorKind::Return); + + // Constants can't `return` so a return block should not be created. + assert_eq!(builder.cached_return_block, None); + + // Constants may be match expressions in which case an unreachable block may + // be created, so terminate it properly. + if let Some(unreachable_block) = builder.cached_unreachable_block { + builder.cfg.terminate(unreachable_block, source_info, TerminatorKind::Unreachable); + } + + builder.finish() +} + +/// Construct MIR for a item that has had errors in type checking. +/// +/// This is required because we may still want to run MIR passes on an item +/// with type errors, but normal MIR construction can't handle that in general. +fn construct_error<'a, 'tcx>(hir: Cx<'a, 'tcx>, body_id: hir::BodyId) -> Body<'tcx> { + let tcx = hir.tcx(); + let owner_id = tcx.hir().body_owner(body_id); + let span = tcx.hir().span(owner_id); + let ty = tcx.ty_error(); + let num_params = match hir.body_owner_kind { + hir::BodyOwnerKind::Fn => tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len(), + hir::BodyOwnerKind::Closure => { + if tcx.hir().body(body_id).generator_kind().is_some() { + // Generators have an implicit `self` parameter *and* a possibly + // implicit resume parameter. + 2 + } else { + // The implicit self parameter adds another local in MIR. + 1 + tcx.hir().fn_decl_by_hir_id(owner_id).unwrap().inputs.len() + } + } + hir::BodyOwnerKind::Const => 0, + hir::BodyOwnerKind::Static(_) => 0, + }; + let mut builder = Builder::new(hir, span, num_params, Safety::Safe, ty, span, None); + let source_info = builder.source_info(span); + // Some MIR passes will expect the number of parameters to match the + // function declaration. + for _ in 0..num_params { + builder.local_decls.push(LocalDecl::with_source_info(ty, source_info)); + } + builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable); + let mut body = builder.finish(); + if tcx.hir().body(body_id).generator_kind.is_some() { + body.yield_ty = Some(ty); + } + body +} + +impl<'a, 'tcx> Builder<'a, 'tcx> { + fn new( + hir: Cx<'a, 'tcx>, + span: Span, + arg_count: usize, + safety: Safety, + return_ty: Ty<'tcx>, + return_span: Span, + generator_kind: Option<GeneratorKind>, + ) -> Builder<'a, 'tcx> { + let lint_level = LintLevel::Explicit(hir.root_lint_level); + let mut builder = Builder { + hir, + cfg: CFG { basic_blocks: IndexVec::new() }, + fn_span: span, + arg_count, + generator_kind, + scopes: Default::default(), + block_context: BlockContext::new(), + source_scopes: IndexVec::new(), + source_scope: OUTERMOST_SOURCE_SCOPE, + guard_context: vec![], + push_unsafe_count: 0, + unpushed_unsafe: safety, + local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1), + canonical_user_type_annotations: IndexVec::new(), + upvar_mutbls: vec![], + var_indices: Default::default(), + unit_temp: None, + var_debug_info: vec![], + cached_resume_block: None, + cached_return_block: None, + cached_unreachable_block: None, + }; + + assert_eq!(builder.cfg.start_new_block(), START_BLOCK); + assert_eq!( + builder.new_source_scope(span, lint_level, Some(safety)), + OUTERMOST_SOURCE_SCOPE + ); + builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None; + + builder + } + + fn finish(self) -> Body<'tcx> { + for (index, block) in self.cfg.basic_blocks.iter().enumerate() { + if block.terminator.is_none() { + span_bug!(self.fn_span, "no terminator on block {:?}", index); + } + } + + Body::new( + self.cfg.basic_blocks, + self.source_scopes, + self.local_decls, + self.canonical_user_type_annotations, + self.arg_count, + self.var_debug_info, + self.fn_span, + self.generator_kind, + ) + } + + fn args_and_body( + &mut self, + mut block: BasicBlock, + fn_def_id: DefId, + arguments: &[ArgInfo<'tcx>], + argument_scope: region::Scope, + ast_body: &'tcx hir::Expr<'tcx>, + ) -> BlockAnd<()> { + // Allocate locals for the function arguments + for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() { + let source_info = + SourceInfo::outermost(arg_opt.map_or(self.fn_span, |arg| arg.pat.span)); + let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info)); + + // If this is a simple binding pattern, give debuginfo a nice name. + if let Some(arg) = arg_opt { + if let Some(ident) = arg.pat.simple_ident() { + self.var_debug_info.push(VarDebugInfo { + name: ident.name, + source_info, + place: arg_local.into(), + }); + } + } + } + + let tcx = self.hir.tcx(); + let tcx_hir = tcx.hir(); + let hir_typeck_results = self.hir.typeck_results(); + + // In analyze_closure() in upvar.rs we gathered a list of upvars used by a + // indexed closure and we stored in a map called closure_captures in TypeckResults + // with the closure's DefId. Here, we run through that vec of UpvarIds for + // the given closure and use the necessary information to create upvar + // debuginfo and to fill `self.upvar_mutbls`. + if let Some(upvars) = hir_typeck_results.closure_captures.get(&fn_def_id) { + let closure_env_arg = Local::new(1); + let mut closure_env_projs = vec![]; + let mut closure_ty = self.local_decls[closure_env_arg].ty; + if let ty::Ref(_, ty, _) = closure_ty.kind { + closure_env_projs.push(ProjectionElem::Deref); + closure_ty = ty; + } + let upvar_substs = match closure_ty.kind { + ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs), + ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs), + _ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty), + }; + let upvar_tys = upvar_substs.upvar_tys(); + let upvars_with_tys = upvars.iter().zip(upvar_tys); + self.upvar_mutbls = upvars_with_tys + .enumerate() + .map(|(i, ((&var_id, &upvar_id), ty))| { + let capture = hir_typeck_results.upvar_capture(upvar_id); + + let mut mutability = Mutability::Not; + let mut name = kw::Invalid; + if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) { + if let hir::PatKind::Binding(_, _, ident, _) = pat.kind { + name = ident.name; + match hir_typeck_results + .extract_binding_mode(tcx.sess, pat.hir_id, pat.span) + { + Some(ty::BindByValue(hir::Mutability::Mut)) => { + mutability = Mutability::Mut; + } + Some(_) => mutability = Mutability::Not, + _ => {} + } + } + } + + let mut projs = closure_env_projs.clone(); + projs.push(ProjectionElem::Field(Field::new(i), ty)); + match capture { + ty::UpvarCapture::ByValue(_) => {} + ty::UpvarCapture::ByRef(..) => { + projs.push(ProjectionElem::Deref); + } + }; + + self.var_debug_info.push(VarDebugInfo { + name, + source_info: SourceInfo::outermost(tcx_hir.span(var_id)), + place: Place { + local: closure_env_arg, + projection: tcx.intern_place_elems(&projs), + }, + }); + + mutability + }) + .collect(); + } + + let mut scope = None; + // Bind the argument patterns + for (index, arg_info) in arguments.iter().enumerate() { + // Function arguments always get the first Local indices after the return place + let local = Local::new(index + 1); + let place = Place::from(local); + let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info; + + // Make sure we drop (parts of) the argument even when not matched on. + self.schedule_drop( + arg_opt.as_ref().map_or(ast_body.span, |arg| arg.pat.span), + argument_scope, + local, + DropKind::Value, + ); + + if let Some(arg) = arg_opt { + let pattern = self.hir.pattern_from_hir(&arg.pat); + let original_source_scope = self.source_scope; + let span = pattern.span; + self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span); + match *pattern.kind { + // Don't introduce extra copies for simple bindings + PatKind::Binding { + mutability, + var, + mode: BindingMode::ByValue, + subpattern: None, + .. + } => { + self.local_decls[local].mutability = mutability; + self.local_decls[local].source_info.scope = self.source_scope; + self.local_decls[local].local_info = if let Some(kind) = self_binding { + Some(box LocalInfo::User(ClearCrossCrate::Set( + BindingForm::ImplicitSelf(*kind), + ))) + } else { + let binding_mode = ty::BindingMode::BindByValue(mutability); + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var( + VarBindingForm { + binding_mode, + opt_ty_info, + opt_match_place: Some((Some(place), span)), + pat_span: span, + }, + )))) + }; + self.var_indices.insert(var, LocalsForNode::One(local)); + } + _ => { + scope = self.declare_bindings( + scope, + ast_body.span, + &pattern, + matches::ArmHasGuard(false), + Some((Some(&place), span)), + ); + unpack!(block = self.place_into_pattern(block, pattern, place, false)); + } + } + self.source_scope = original_source_scope; + } + } + + // Enter the argument pattern bindings source scope, if it exists. + if let Some(source_scope) = scope { + self.source_scope = source_scope; + } + + let body = self.hir.mirror(ast_body); + self.into(Place::return_place(), block, body) + } + + fn set_correct_source_scope_for_arg( + &mut self, + arg_hir_id: hir::HirId, + original_source_scope: SourceScope, + pattern_span: Span, + ) { + let tcx = self.hir.tcx(); + let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir.root_lint_level); + let parent_root = tcx.maybe_lint_level_root_bounded( + self.source_scopes[original_source_scope] + .local_data + .as_ref() + .assert_crate_local() + .lint_root, + self.hir.root_lint_level, + ); + if current_root != parent_root { + self.source_scope = + self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None); + } + } + + fn get_unit_temp(&mut self) -> Place<'tcx> { + match self.unit_temp { + Some(tmp) => tmp, + None => { + let ty = self.hir.unit_ty(); + let fn_span = self.fn_span; + let tmp = self.temp(ty, fn_span); + self.unit_temp = Some(tmp); + tmp + } + } + } + + fn return_block(&mut self) -> BasicBlock { + match self.cached_return_block { + Some(rb) => rb, + None => { + let rb = self.cfg.start_new_block(); + self.cached_return_block = Some(rb); + rb + } + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Builder methods are broken up into modules, depending on what kind +// of thing is being lowered. Note that they use the `unpack` macro +// above extensively. + +mod block; +mod cfg; +mod expr; +mod into; +mod matches; +mod misc; +mod scope; |