| //! See docs in build/expr/mod.rs |
| |
| use crate::build::expr::category::{Category, RvalueFunc}; |
| use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder}; |
| use crate::thir::*; |
| use rustc_ast::InlineAsmOptions; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stack::ensure_sufficient_stack; |
| use rustc_hir as hir; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::{self, CanonicalUserTypeAnnotation}; |
| use rustc_span::symbol::sym; |
| |
| use rustc_target::spec::abi::Abi; |
| |
| impl<'a, 'tcx> Builder<'a, 'tcx> { |
| /// Compile `expr`, storing the result into `destination`, which |
| /// is assumed to be uninitialized. |
| crate fn into_expr( |
| &mut self, |
| destination: Place<'tcx>, |
| mut block: BasicBlock, |
| expr: Expr<'tcx>, |
| ) -> BlockAnd<()> { |
| debug!("into_expr(destination={:?}, block={:?}, expr={:?})", destination, block, expr); |
| |
| // since we frequently have to reference `self` from within a |
| // closure, where `self` would be shadowed, it's easier to |
| // just use the name `this` uniformly |
| let this = self; |
| let expr_span = expr.span; |
| let source_info = this.source_info(expr_span); |
| |
| let expr_is_block_or_scope = match expr.kind { |
| ExprKind::Block { .. } => true, |
| ExprKind::Scope { .. } => true, |
| _ => false, |
| }; |
| |
| if !expr_is_block_or_scope { |
| this.block_context.push(BlockFrame::SubExpr); |
| } |
| |
| let block_and = match expr.kind { |
| ExprKind::Scope { region_scope, lint_level, value } => { |
| let region_scope = (region_scope, source_info); |
| ensure_sufficient_stack(|| { |
| this.in_scope(region_scope, lint_level, |this| { |
| this.into(destination, block, value) |
| }) |
| }) |
| } |
| ExprKind::Block { body: ast_block } => { |
| this.ast_block(destination, block, ast_block, source_info) |
| } |
| ExprKind::Match { scrutinee, arms } => { |
| this.match_expr(destination, expr_span, block, scrutinee, arms) |
| } |
| ExprKind::NeverToAny { source } => { |
| let source = this.hir.mirror(source); |
| let is_call = match source.kind { |
| ExprKind::Call { .. } | ExprKind::InlineAsm { .. } => true, |
| _ => false, |
| }; |
| |
| // (#66975) Source could be a const of type `!`, so has to |
| // exist in the generated MIR. |
| unpack!(block = this.as_temp(block, this.local_scope(), source, Mutability::Mut,)); |
| |
| // This is an optimization. If the expression was a call then we already have an |
| // unreachable block. Don't bother to terminate it and create a new one. |
| if is_call { |
| block.unit() |
| } else { |
| this.cfg.terminate(block, source_info, TerminatorKind::Unreachable); |
| let end_block = this.cfg.start_new_block(); |
| end_block.unit() |
| } |
| } |
| ExprKind::LogicalOp { op, lhs, rhs } => { |
| // And: |
| // |
| // [block: If(lhs)] -true-> [else_block: If(rhs)] -true-> [true_block] |
| // | | (false) |
| // +----------false-----------+------------------> [false_block] |
| // |
| // Or: |
| // |
| // [block: If(lhs)] -false-> [else_block: If(rhs)] -true-> [true_block] |
| // | (true) | (false) |
| // [true_block] [false_block] |
| |
| let (true_block, false_block, mut else_block, join_block) = ( |
| this.cfg.start_new_block(), |
| this.cfg.start_new_block(), |
| this.cfg.start_new_block(), |
| this.cfg.start_new_block(), |
| ); |
| |
| let lhs = unpack!(block = this.as_local_operand(block, lhs)); |
| let blocks = match op { |
| LogicalOp::And => (else_block, false_block), |
| LogicalOp::Or => (true_block, else_block), |
| }; |
| let term = TerminatorKind::if_(this.hir.tcx(), lhs, blocks.0, blocks.1); |
| this.cfg.terminate(block, source_info, term); |
| |
| let rhs = unpack!(else_block = this.as_local_operand(else_block, rhs)); |
| let term = TerminatorKind::if_(this.hir.tcx(), rhs, true_block, false_block); |
| this.cfg.terminate(else_block, source_info, term); |
| |
| this.cfg.push_assign_constant( |
| true_block, |
| source_info, |
| destination, |
| Constant { span: expr_span, user_ty: None, literal: this.hir.true_literal() }, |
| ); |
| |
| this.cfg.push_assign_constant( |
| false_block, |
| source_info, |
| destination, |
| Constant { span: expr_span, user_ty: None, literal: this.hir.false_literal() }, |
| ); |
| |
| // Link up both branches: |
| this.cfg.goto(true_block, source_info, join_block); |
| this.cfg.goto(false_block, source_info, join_block); |
| join_block.unit() |
| } |
| ExprKind::Loop { body } => { |
| // [block] |
| // | |
| // [loop_block] -> [body_block] -/eval. body/-> [body_block_end] |
| // | ^ | |
| // false link | | |
| // | +-----------------------------------------+ |
| // +-> [diverge_cleanup] |
| // The false link is required to make sure borrowck considers unwinds through the |
| // body, even when the exact code in the body cannot unwind |
| |
| let loop_block = this.cfg.start_new_block(); |
| |
| // Start the loop. |
| this.cfg.goto(block, source_info, loop_block); |
| |
| this.in_breakable_scope(Some(loop_block), destination, expr_span, move |this| { |
| // conduct the test, if necessary |
| let body_block = this.cfg.start_new_block(); |
| this.cfg.terminate( |
| loop_block, |
| source_info, |
| TerminatorKind::FalseUnwind { real_target: body_block, unwind: None }, |
| ); |
| this.diverge_from(loop_block); |
| |
| // The “return” value of the loop body must always be an unit. We therefore |
| // introduce a unit temporary as the destination for the loop body. |
| let tmp = this.get_unit_temp(); |
| // Execute the body, branching back to the test. |
| let body_block_end = unpack!(this.into(tmp, body_block, body)); |
| this.cfg.goto(body_block_end, source_info, loop_block); |
| |
| // Loops are only exited by `break` expressions. |
| None |
| }) |
| } |
| ExprKind::Call { ty, fun, args, from_hir_call, fn_span } => { |
| let intrinsic = match *ty.kind() { |
| ty::FnDef(def_id, _) => { |
| let f = ty.fn_sig(this.hir.tcx()); |
| if f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic { |
| Some(this.hir.tcx().item_name(def_id)) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| }; |
| let fun = unpack!(block = this.as_local_operand(block, fun)); |
| if let Some(sym::move_val_init) = intrinsic { |
| // `move_val_init` has "magic" semantics - the second argument is |
| // always evaluated "directly" into the first one. |
| |
| let mut args = args.into_iter(); |
| let ptr = args.next().expect("0 arguments to `move_val_init`"); |
| let val = args.next().expect("1 argument to `move_val_init`"); |
| assert!(args.next().is_none(), ">2 arguments to `move_val_init`"); |
| |
| let ptr = this.hir.mirror(ptr); |
| let ptr_ty = ptr.ty; |
| // Create an *internal* temp for the pointer, so that unsafety |
| // checking won't complain about the raw pointer assignment. |
| let ptr_temp = this |
| .local_decls |
| .push(LocalDecl::with_source_info(ptr_ty, source_info).internal()); |
| let ptr_temp = Place::from(ptr_temp); |
| let block = unpack!(this.into(ptr_temp, block, ptr)); |
| this.into(this.hir.tcx().mk_place_deref(ptr_temp), block, val) |
| } else { |
| let args: Vec<_> = args |
| .into_iter() |
| .map(|arg| unpack!(block = this.as_local_call_operand(block, arg))) |
| .collect(); |
| |
| let success = this.cfg.start_new_block(); |
| |
| this.record_operands_moved(&args); |
| |
| debug!("into_expr: fn_span={:?}", fn_span); |
| |
| this.cfg.terminate( |
| block, |
| source_info, |
| TerminatorKind::Call { |
| func: fun, |
| args, |
| cleanup: None, |
| // FIXME(varkor): replace this with an uninhabitedness-based check. |
| // This requires getting access to the current module to call |
| // `tcx.is_ty_uninhabited_from`, which is currently tricky to do. |
| destination: if expr.ty.is_never() { |
| None |
| } else { |
| Some((destination, success)) |
| }, |
| from_hir_call, |
| fn_span, |
| }, |
| ); |
| this.diverge_from(block); |
| success.unit() |
| } |
| } |
| ExprKind::Use { source } => this.into(destination, block, source), |
| ExprKind::Borrow { arg, borrow_kind } => { |
| // We don't do this in `as_rvalue` because we use `as_place` |
| // for borrow expressions, so we cannot create an `RValue` that |
| // remains valid across user code. `as_rvalue` is usually called |
| // by this method anyway, so this shouldn't cause too many |
| // unnecessary temporaries. |
| let arg_place = match borrow_kind { |
| BorrowKind::Shared => unpack!(block = this.as_read_only_place(block, arg)), |
| _ => unpack!(block = this.as_place(block, arg)), |
| }; |
| let borrow = |
| Rvalue::Ref(this.hir.tcx().lifetimes.re_erased, borrow_kind, arg_place); |
| this.cfg.push_assign(block, source_info, destination, borrow); |
| block.unit() |
| } |
| ExprKind::AddressOf { mutability, arg } => { |
| let place = match mutability { |
| hir::Mutability::Not => this.as_read_only_place(block, arg), |
| hir::Mutability::Mut => this.as_place(block, arg), |
| }; |
| let address_of = Rvalue::AddressOf(mutability, unpack!(block = place)); |
| this.cfg.push_assign(block, source_info, destination, address_of); |
| block.unit() |
| } |
| ExprKind::Adt { adt_def, variant_index, substs, user_ty, fields, base } => { |
| // See the notes for `ExprKind::Array` in `as_rvalue` and for |
| // `ExprKind::Borrow` above. |
| let is_union = adt_def.is_union(); |
| let active_field_index = if is_union { Some(fields[0].name.index()) } else { None }; |
| |
| let scope = this.local_scope(); |
| |
| // first process the set of fields that were provided |
| // (evaluating them in order given by user) |
| let fields_map: FxHashMap<_, _> = fields |
| .into_iter() |
| .map(|f| (f.name, unpack!(block = this.as_operand(block, scope, f.expr)))) |
| .collect(); |
| |
| let field_names = this.hir.all_fields(adt_def, variant_index); |
| |
| let fields = if let Some(FruInfo { base, field_types }) = base { |
| let base = unpack!(block = this.as_place(block, base)); |
| |
| // MIR does not natively support FRU, so for each |
| // base-supplied field, generate an operand that |
| // reads it from the base. |
| field_names |
| .into_iter() |
| .zip(field_types.into_iter()) |
| .map(|(n, ty)| match fields_map.get(&n) { |
| Some(v) => v.clone(), |
| None => this.consume_by_copy_or_move( |
| this.hir.tcx().mk_place_field(base, n, ty), |
| ), |
| }) |
| .collect() |
| } else { |
| field_names.iter().filter_map(|n| fields_map.get(n).cloned()).collect() |
| }; |
| |
| let inferred_ty = expr.ty; |
| let user_ty = user_ty.map(|ty| { |
| this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation { |
| span: source_info.span, |
| user_ty: ty, |
| inferred_ty, |
| }) |
| }); |
| let adt = box AggregateKind::Adt( |
| adt_def, |
| variant_index, |
| substs, |
| user_ty, |
| active_field_index, |
| ); |
| this.cfg.push_assign( |
| block, |
| source_info, |
| destination, |
| Rvalue::Aggregate(adt, fields), |
| ); |
| block.unit() |
| } |
| ExprKind::InlineAsm { template, operands, options, line_spans } => { |
| use crate::thir; |
| use rustc_middle::mir; |
| let operands = operands |
| .into_iter() |
| .map(|op| match op { |
| thir::InlineAsmOperand::In { reg, expr } => mir::InlineAsmOperand::In { |
| reg, |
| value: unpack!(block = this.as_local_operand(block, expr)), |
| }, |
| thir::InlineAsmOperand::Out { reg, late, expr } => { |
| mir::InlineAsmOperand::Out { |
| reg, |
| late, |
| place: expr.map(|expr| unpack!(block = this.as_place(block, expr))), |
| } |
| } |
| thir::InlineAsmOperand::InOut { reg, late, expr } => { |
| let place = unpack!(block = this.as_place(block, expr)); |
| mir::InlineAsmOperand::InOut { |
| reg, |
| late, |
| // This works because asm operands must be Copy |
| in_value: Operand::Copy(place), |
| out_place: Some(place), |
| } |
| } |
| thir::InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => { |
| mir::InlineAsmOperand::InOut { |
| reg, |
| late, |
| in_value: unpack!(block = this.as_local_operand(block, in_expr)), |
| out_place: out_expr.map(|out_expr| { |
| unpack!(block = this.as_place(block, out_expr)) |
| }), |
| } |
| } |
| thir::InlineAsmOperand::Const { expr } => mir::InlineAsmOperand::Const { |
| value: unpack!(block = this.as_local_operand(block, expr)), |
| }, |
| thir::InlineAsmOperand::SymFn { expr } => { |
| mir::InlineAsmOperand::SymFn { value: box this.as_constant(expr) } |
| } |
| thir::InlineAsmOperand::SymStatic { def_id } => { |
| mir::InlineAsmOperand::SymStatic { def_id } |
| } |
| }) |
| .collect(); |
| |
| let destination = this.cfg.start_new_block(); |
| |
| this.cfg.terminate( |
| block, |
| source_info, |
| TerminatorKind::InlineAsm { |
| template, |
| operands, |
| options, |
| line_spans, |
| destination: if options.contains(InlineAsmOptions::NORETURN) { |
| None |
| } else { |
| Some(destination) |
| }, |
| }, |
| ); |
| destination.unit() |
| } |
| |
| // These cases don't actually need a destination |
| ExprKind::Assign { .. } |
| | ExprKind::AssignOp { .. } |
| | ExprKind::LlvmInlineAsm { .. } => { |
| unpack!(block = this.stmt_expr(block, expr, None)); |
| this.cfg.push_assign_unit(block, source_info, destination, this.hir.tcx()); |
| block.unit() |
| } |
| |
| ExprKind::Continue { .. } | ExprKind::Break { .. } | ExprKind::Return { .. } => { |
| unpack!(block = this.stmt_expr(block, expr, None)); |
| // No assign, as these have type `!`. |
| block.unit() |
| } |
| |
| // Avoid creating a temporary |
| ExprKind::VarRef { .. } |
| | ExprKind::SelfRef |
| | ExprKind::PlaceTypeAscription { .. } |
| | ExprKind::ValueTypeAscription { .. } => { |
| debug_assert!(Category::of(&expr.kind) == Some(Category::Place)); |
| |
| let place = unpack!(block = this.as_place(block, expr)); |
| let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place)); |
| this.cfg.push_assign(block, source_info, destination, rvalue); |
| block.unit() |
| } |
| ExprKind::Index { .. } | ExprKind::Deref { .. } | ExprKind::Field { .. } => { |
| debug_assert!(Category::of(&expr.kind) == Some(Category::Place)); |
| |
| // Create a "fake" temporary variable so that we check that the |
| // value is Sized. Usually, this is caught in type checking, but |
| // in the case of box expr there is no such check. |
| if !destination.projection.is_empty() { |
| this.local_decls.push(LocalDecl::new(expr.ty, expr.span)); |
| } |
| |
| debug_assert!(Category::of(&expr.kind) == Some(Category::Place)); |
| |
| let place = unpack!(block = this.as_place(block, expr)); |
| let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place)); |
| this.cfg.push_assign(block, source_info, destination, rvalue); |
| block.unit() |
| } |
| |
| ExprKind::Yield { value } => { |
| let scope = this.local_scope(); |
| let value = unpack!(block = this.as_operand(block, scope, value)); |
| let resume = this.cfg.start_new_block(); |
| this.cfg.terminate( |
| block, |
| source_info, |
| TerminatorKind::Yield { value, resume, resume_arg: destination, drop: None }, |
| ); |
| this.generator_drop_cleanup(block); |
| resume.unit() |
| } |
| |
| // these are the cases that are more naturally handled by some other mode |
| ExprKind::Unary { .. } |
| | ExprKind::Binary { .. } |
| | ExprKind::Box { .. } |
| | ExprKind::Cast { .. } |
| | ExprKind::Pointer { .. } |
| | ExprKind::Repeat { .. } |
| | ExprKind::Array { .. } |
| | ExprKind::Tuple { .. } |
| | ExprKind::Closure { .. } |
| | ExprKind::ConstBlock { .. } |
| | ExprKind::Literal { .. } |
| | ExprKind::ThreadLocalRef(_) |
| | ExprKind::StaticRef { .. } => { |
| debug_assert!(match Category::of(&expr.kind).unwrap() { |
| // should be handled above |
| Category::Rvalue(RvalueFunc::Into) => false, |
| |
| // must be handled above or else we get an |
| // infinite loop in the builder; see |
| // e.g., `ExprKind::VarRef` above |
| Category::Place => false, |
| |
| _ => true, |
| }); |
| |
| let rvalue = unpack!(block = this.as_local_rvalue(block, expr)); |
| this.cfg.push_assign(block, source_info, destination, rvalue); |
| block.unit() |
| } |
| }; |
| |
| if !expr_is_block_or_scope { |
| let popped = this.block_context.pop(); |
| assert!(popped.is_some()); |
| } |
| |
| block_and |
| } |
| } |