1 // Copyright 2015 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.
11 //! See docs in build/expr/mod.rs
13 use rustc_data_structures::fnv::FnvHashMap;
15 use build::{BlockAnd, Builder};
16 use build::expr::category::{Category, RvalueFunc};
20 impl<'a,'tcx> Builder<'a,'tcx> {
21 /// Compile `expr`, yielding an rvalue.
22 pub fn as_rvalue<M>(&mut self, block: BasicBlock, expr: M) -> BlockAnd<Rvalue<'tcx>>
23 where M: Mirror<'tcx, Output = Expr<'tcx>>
25 let expr = self.hir.mirror(expr);
26 self.expr_as_rvalue(block, expr)
29 fn expr_as_rvalue(&mut self,
30 mut block: BasicBlock,
32 -> BlockAnd<Rvalue<'tcx>> {
33 debug!("expr_as_rvalue(block={:?}, expr={:?})", block, expr);
36 let expr_span = expr.span;
39 ExprKind::Scope { extent, value } => {
40 this.in_scope(extent, block, |this| this.as_rvalue(block, value))
42 ExprKind::InlineAsm { asm } => {
43 block.and(Rvalue::InlineAsm(asm))
45 ExprKind::Repeat { value, count } => {
46 let value_operand = unpack!(block = this.as_operand(block, value));
47 let count = this.as_constant(count);
48 block.and(Rvalue::Repeat(value_operand, count))
50 ExprKind::Borrow { region, borrow_kind, arg } => {
51 let arg_lvalue = unpack!(block = this.as_lvalue(block, arg));
52 block.and(Rvalue::Ref(region, borrow_kind, arg_lvalue))
54 ExprKind::Binary { op, lhs, rhs } => {
55 let lhs = unpack!(block = this.as_operand(block, lhs));
56 let rhs = unpack!(block = this.as_operand(block, rhs));
57 block.and(Rvalue::BinaryOp(op, lhs, rhs))
59 ExprKind::Unary { op, arg } => {
60 let arg = unpack!(block = this.as_operand(block, arg));
61 block.and(Rvalue::UnaryOp(op, arg))
63 ExprKind::Box { value } => {
64 let value = this.hir.mirror(value);
65 let value_ty = value.ty.clone();
66 let result = this.temp(value_ty.clone());
68 // to start, malloc some memory of suitable type (thus far, uninitialized):
69 let rvalue = Rvalue::Box(value.ty.clone());
70 this.cfg.push_assign(block, expr_span, &result, rvalue);
72 // schedule a shallow free of that memory, lest we unwind:
73 let extent = this.extent_of_innermost_scope().unwrap();
74 this.schedule_drop(expr_span, extent, DropKind::Free, &result, value_ty);
76 // initialize the box contents:
77 let contents = result.clone().deref();
78 unpack!(block = this.into(&contents, block, value));
80 // now that the result is fully initialized, cancel the drop
81 // by "using" the result (which is linear):
82 block.and(Rvalue::Use(Operand::Consume(result)))
84 ExprKind::Cast { source } => {
85 let source = unpack!(block = this.as_operand(block, source));
86 block.and(Rvalue::Cast(CastKind::Misc, source, expr.ty))
88 ExprKind::ReifyFnPointer { source } => {
89 let source = unpack!(block = this.as_operand(block, source));
90 block.and(Rvalue::Cast(CastKind::ReifyFnPointer, source, expr.ty))
92 ExprKind::UnsafeFnPointer { source } => {
93 let source = unpack!(block = this.as_operand(block, source));
94 block.and(Rvalue::Cast(CastKind::UnsafeFnPointer, source, expr.ty))
96 ExprKind::Unsize { source } => {
97 let source = unpack!(block = this.as_operand(block, source));
98 block.and(Rvalue::Cast(CastKind::Unsize, source, expr.ty))
100 ExprKind::Vec { fields } => {
101 // (*) We would (maybe) be closer to trans if we
102 // handled this and other aggregate cases via
103 // `into()`, not `as_rvalue` -- in that case, instead
108 // dest = Rvalue::Aggregate(Foo, [tmp1, tmp2])
110 // we could just generate
115 // The problem is that then we would need to:
117 // (a) have a more complex mechanism for handling
119 // (b) distinguish the case where the type `Foo` has a
120 // destructor, in which case creating an instance
121 // as a whole "arms" the destructor, and you can't
122 // write individual fields; and,
123 // (c) handle the case where the type Foo has no
124 // fields. We don't want `let x: ();` to compile
125 // to the same MIR as `let x = ();`.
127 // first process the set of fields
130 .map(|f| unpack!(block = this.as_operand(block, f)))
133 block.and(Rvalue::Aggregate(AggregateKind::Vec, fields))
135 ExprKind::Tuple { fields } => { // see (*) above
136 // first process the set of fields
139 .map(|f| unpack!(block = this.as_operand(block, f)))
142 block.and(Rvalue::Aggregate(AggregateKind::Tuple, fields))
144 ExprKind::Closure { closure_id, substs, upvars } => { // see (*) above
147 .map(|upvar| unpack!(block = this.as_operand(block, upvar)))
149 block.and(Rvalue::Aggregate(AggregateKind::Closure(closure_id, substs), upvars))
151 ExprKind::Adt { adt_def, variant_index, substs, fields, base } => { // see (*) above
152 // first process the set of fields that were provided
153 // (evaluating them in order given by user)
154 let fields_map: FnvHashMap<_, _> =
156 .map(|f| (f.name, unpack!(block = this.as_operand(block, f.expr))))
159 // if base expression is given, evaluate it now
160 let base = base.map(|base| unpack!(block = this.as_lvalue(block, base)));
162 // get list of all fields that we will need
163 let field_names = this.hir.all_fields(adt_def, variant_index);
165 // for the actual values we use, take either the
166 // expr the user specified or, if they didn't
167 // specify something for this field name, create a
168 // path relative to the base (which must have been
169 // supplied, or the IR is internally
172 field_names.into_iter()
173 .map(|n| match fields_map.get(&n) {
174 Some(v) => v.clone(),
175 None => Operand::Consume(base.clone().unwrap().field(n)),
179 block.and(Rvalue::Aggregate(AggregateKind::Adt(adt_def, variant_index, substs),
182 ExprKind::Literal { .. } |
183 ExprKind::Block { .. } |
184 ExprKind::Match { .. } |
185 ExprKind::If { .. } |
186 ExprKind::Loop { .. } |
187 ExprKind::LogicalOp { .. } |
188 ExprKind::Call { .. } |
189 ExprKind::Field { .. } |
190 ExprKind::Deref { .. } |
191 ExprKind::Index { .. } |
192 ExprKind::VarRef { .. } |
194 ExprKind::Assign { .. } |
195 ExprKind::AssignOp { .. } |
196 ExprKind::Break { .. } |
197 ExprKind::Continue { .. } |
198 ExprKind::Return { .. } |
199 ExprKind::StaticRef { .. } => {
200 // these do not have corresponding `Rvalue` variants,
201 // so make an operand and then return that
202 debug_assert!(match Category::of(&expr.kind) {
203 Some(Category::Rvalue(RvalueFunc::AsRvalue)) => false,
206 let operand = unpack!(block = this.as_operand(block, expr));
207 block.and(Rvalue::Use(operand))