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::fx::FxHashMap;
14 use rustc_data_structures::indexed_vec::Idx;
16 use build::expr::category::{Category, RvalueFunc};
17 use build::{BlockAnd, BlockAndExtension, Builder};
19 use rustc::middle::region;
20 use rustc::mir::interpret::EvalErrorKind;
22 use rustc::ty::{self, Ty, UpvarSubsts};
25 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
26 /// See comment on `as_local_operand`
27 pub fn as_local_rvalue<M>(&mut self, block: BasicBlock, expr: M) -> BlockAnd<Rvalue<'tcx>>
29 M: Mirror<'tcx, Output = Expr<'tcx>>,
31 let local_scope = self.local_scope();
32 self.as_rvalue(block, local_scope, expr)
35 /// Compile `expr`, yielding an rvalue.
39 scope: Option<region::Scope>,
41 ) -> BlockAnd<Rvalue<'tcx>>
43 M: Mirror<'tcx, Output = Expr<'tcx>>,
45 let expr = self.hir.mirror(expr);
46 self.expr_as_rvalue(block, scope, expr)
51 mut block: BasicBlock,
52 scope: Option<region::Scope>,
54 ) -> BlockAnd<Rvalue<'tcx>> {
56 "expr_as_rvalue(block={:?}, scope={:?}, expr={:?})",
61 let expr_span = expr.span;
62 let source_info = this.source_info(expr_span);
70 let region_scope = (region_scope, source_info);
71 this.in_scope(region_scope, lint_level, block, |this| {
72 this.as_rvalue(block, scope, value)
75 ExprKind::Repeat { value, count } => {
76 let value_operand = unpack!(block = this.as_operand(block, scope, value));
77 block.and(Rvalue::Repeat(value_operand, count))
84 let arg_place = match borrow_kind {
85 BorrowKind::Shared => unpack!(block = this.as_read_only_place(block, arg)),
86 _ => unpack!(block = this.as_place(block, arg)),
88 block.and(Rvalue::Ref(region, borrow_kind, arg_place))
90 ExprKind::Binary { op, lhs, rhs } => {
91 let lhs = unpack!(block = this.as_operand(block, scope, lhs));
92 let rhs = unpack!(block = this.as_operand(block, scope, rhs));
93 this.build_binary_op(block, op, expr_span, expr.ty, lhs, rhs)
95 ExprKind::Unary { op, arg } => {
96 let arg = unpack!(block = this.as_operand(block, scope, arg));
97 // Check for -MIN on signed integers
98 if this.hir.check_overflow() && op == UnOp::Neg && expr.ty.is_signed() {
99 let bool_ty = this.hir.bool_ty();
101 let minval = this.minval_literal(expr_span, expr.ty);
102 let is_min = this.temp(bool_ty, expr_span);
104 this.cfg.push_assign(
108 Rvalue::BinaryOp(BinOp::Eq, arg.to_copy(), minval),
113 Operand::Move(is_min),
115 EvalErrorKind::OverflowNeg,
119 block.and(Rvalue::UnaryOp(op, arg))
121 ExprKind::Box { value } => {
122 let value = this.hir.mirror(value);
123 // The `Box<T>` temporary created here is not a part of the HIR,
124 // and therefore is not considered during generator OIBIT
125 // determination. See the comment about `box` at `yield_in_scope`.
128 .push(LocalDecl::new_internal(expr.ty, expr_span));
133 kind: StatementKind::StorageLive(result),
136 if let Some(scope) = scope {
137 // schedule a shallow free of that memory, lest we unwind:
138 this.schedule_drop_storage_and_value(
141 &Place::Local(result),
146 // malloc some memory of suitable type (thus far, uninitialized):
147 let box_ = Rvalue::NullaryOp(NullOp::Box, value.ty);
149 .push_assign(block, source_info, &Place::Local(result), box_);
151 // initialize the box contents:
152 unpack!(block = this.into(&Place::Local(result).deref(), block, value));
153 block.and(Rvalue::Use(Operand::Move(Place::Local(result))))
155 ExprKind::Cast { source } => {
156 let source = this.hir.mirror(source);
158 let source = unpack!(block = this.as_operand(block, scope, source));
159 block.and(Rvalue::Cast(CastKind::Misc, source, expr.ty))
161 ExprKind::Use { source } => {
162 let source = unpack!(block = this.as_operand(block, scope, source));
163 block.and(Rvalue::Use(source))
165 ExprKind::ReifyFnPointer { source } => {
166 let source = unpack!(block = this.as_operand(block, scope, source));
167 block.and(Rvalue::Cast(CastKind::ReifyFnPointer, source, expr.ty))
169 ExprKind::UnsafeFnPointer { source } => {
170 let source = unpack!(block = this.as_operand(block, scope, source));
171 block.and(Rvalue::Cast(CastKind::UnsafeFnPointer, source, expr.ty))
173 ExprKind::ClosureFnPointer { source } => {
174 let source = unpack!(block = this.as_operand(block, scope, source));
175 block.and(Rvalue::Cast(CastKind::ClosureFnPointer, source, expr.ty))
177 ExprKind::Unsize { source } => {
178 let source = unpack!(block = this.as_operand(block, scope, source));
179 block.and(Rvalue::Cast(CastKind::Unsize, source, expr.ty))
181 ExprKind::Array { fields } => {
182 // (*) We would (maybe) be closer to codegen if we
183 // handled this and other aggregate cases via
184 // `into()`, not `as_rvalue` -- in that case, instead
189 // dest = Rvalue::Aggregate(Foo, [tmp1, tmp2])
191 // we could just generate
196 // The problem is that then we would need to:
198 // (a) have a more complex mechanism for handling
200 // (b) distinguish the case where the type `Foo` has a
201 // destructor, in which case creating an instance
202 // as a whole "arms" the destructor, and you can't
203 // write individual fields; and,
204 // (c) handle the case where the type Foo has no
205 // fields. We don't want `let x: ();` to compile
206 // to the same MIR as `let x = ();`.
208 // first process the set of fields
209 let el_ty = expr.ty.sequence_element_type(this.hir.tcx());
210 let fields: Vec<_> = fields
212 .map(|f| unpack!(block = this.as_operand(block, scope, f)))
215 block.and(Rvalue::Aggregate(box AggregateKind::Array(el_ty), fields))
217 ExprKind::Tuple { fields } => {
219 // first process the set of fields
220 let fields: Vec<_> = fields
222 .map(|f| unpack!(block = this.as_operand(block, scope, f)))
225 block.and(Rvalue::Aggregate(box AggregateKind::Tuple, fields))
234 let mut operands: Vec<_> = upvars
237 let upvar = this.hir.mirror(upvar);
238 match Category::of(&upvar.kind) {
239 // Use as_place to avoid creating a temporary when
240 // moving a variable into a closure, so that
241 // borrowck knows which variables to mark as being
242 // used as mut. This is OK here because the upvar
243 // expressions have no side effects and act on
245 // This occurs when capturing by copy/move, while
246 // by reference captures use as_operand
247 Some(Category::Place) => {
248 let place = unpack!(block = this.as_place(block, upvar));
249 this.consume_by_copy_or_move(place)
252 // Turn mutable borrow captures into unique
253 // borrow captures when capturing an immutable
254 // variable. This is sound because the mutation
255 // that caused the capture will cause an error.
260 allow_two_phase_borrow: false,
265 block = this.limit_capture_mutability(
266 upvar.span, upvar.ty, scope, block, arg, region,
269 _ => unpack!(block = this.as_operand(block, scope, upvar)),
274 let result = match substs {
275 UpvarSubsts::Generator(substs) => {
276 let movability = movability.unwrap();
277 // Add the state operand since it follows the upvars in the generator
278 // struct. See librustc_mir/transform/generator.rs for more details.
279 operands.push(Operand::Constant(box Constant {
281 ty: this.hir.tcx().types.u32,
283 literal: ty::Const::from_bits(
286 ty::ParamEnv::empty().and(this.hir.tcx().types.u32),
289 box AggregateKind::Generator(closure_id, substs, movability)
291 UpvarSubsts::Closure(substs) => box AggregateKind::Closure(closure_id, substs),
293 block.and(Rvalue::Aggregate(result, operands))
304 let is_union = adt_def.is_union();
305 let active_field_index = if is_union {
306 Some(fields[0].name.index())
311 // first process the set of fields that were provided
312 // (evaluating them in order given by user)
313 let fields_map: FxHashMap<_, _> = fields
318 unpack!(block = this.as_operand(block, scope, f.expr)),
322 let field_names = this.hir.all_fields(adt_def, variant_index);
324 let fields = if let Some(FruInfo { base, field_types }) = base {
325 let base = unpack!(block = this.as_place(block, base));
327 // MIR does not natively support FRU, so for each
328 // base-supplied field, generate an operand that
329 // reads it from the base.
332 .zip(field_types.into_iter())
333 .map(|(n, ty)| match fields_map.get(&n) {
334 Some(v) => v.clone(),
335 None => this.consume_by_copy_or_move(base.clone().field(n, ty)),
340 .filter_map(|n| fields_map.get(n).cloned())
344 let adt = box AggregateKind::Adt(
351 block.and(Rvalue::Aggregate(adt, fields))
353 ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => {
354 block = unpack!(this.stmt_expr(block, expr, None));
355 block.and(this.unit_rvalue())
357 ExprKind::Yield { value } => {
358 let value = unpack!(block = this.as_operand(block, scope, value));
359 let resume = this.cfg.start_new_block();
360 let cleanup = this.generator_drop_cleanup();
364 TerminatorKind::Yield {
370 resume.and(this.unit_rvalue())
372 ExprKind::Literal { .. }
373 | ExprKind::Block { .. }
374 | ExprKind::Match { .. }
375 | ExprKind::If { .. }
376 | ExprKind::NeverToAny { .. }
377 | ExprKind::Loop { .. }
378 | ExprKind::LogicalOp { .. }
379 | ExprKind::Call { .. }
380 | ExprKind::Field { .. }
381 | ExprKind::Deref { .. }
382 | ExprKind::Index { .. }
383 | ExprKind::VarRef { .. }
385 | ExprKind::Break { .. }
386 | ExprKind::Continue { .. }
387 | ExprKind::Return { .. }
388 | ExprKind::InlineAsm { .. }
389 | ExprKind::StaticRef { .. }
390 | ExprKind::PlaceTypeAscription { .. }
391 | ExprKind::ValueTypeAscription { .. } => {
392 // these do not have corresponding `Rvalue` variants,
393 // so make an operand and then return that
394 debug_assert!(match Category::of(&expr.kind) {
395 Some(Category::Rvalue(RvalueFunc::AsRvalue)) => false,
398 let operand = unpack!(block = this.as_operand(block, scope, expr));
399 block.and(Rvalue::Use(operand))
404 pub fn build_binary_op(
406 mut block: BasicBlock,
412 ) -> BlockAnd<Rvalue<'tcx>> {
413 let source_info = self.source_info(span);
414 let bool_ty = self.hir.bool_ty();
415 if self.hir.check_overflow() && op.is_checkable() && ty.is_integral() {
416 let result_tup = self.hir.tcx().intern_tup(&[ty, bool_ty]);
417 let result_value = self.temp(result_tup, span);
419 self.cfg.push_assign(
423 Rvalue::CheckedBinaryOp(op, lhs, rhs),
425 let val_fld = Field::new(0);
426 let of_fld = Field::new(1);
428 let val = result_value.clone().field(val_fld, ty);
429 let of = result_value.field(of_fld, bool_ty);
431 let err = EvalErrorKind::Overflow(op);
433 block = self.assert(block, Operand::Move(of), false, err, span);
435 block.and(Rvalue::Use(Operand::Move(val)))
437 if ty.is_integral() && (op == BinOp::Div || op == BinOp::Rem) {
438 // Checking division and remainder is more complex, since we 1. always check
439 // and 2. there are two possible failure cases, divide-by-zero and overflow.
441 let (zero_err, overflow_err) = if op == BinOp::Div {
442 (EvalErrorKind::DivisionByZero, EvalErrorKind::Overflow(op))
444 (EvalErrorKind::RemainderByZero, EvalErrorKind::Overflow(op))
448 let is_zero = self.temp(bool_ty, span);
449 let zero = self.zero_literal(span, ty);
450 self.cfg.push_assign(
454 Rvalue::BinaryOp(BinOp::Eq, rhs.to_copy(), zero),
457 block = self.assert(block, Operand::Move(is_zero), false, zero_err, span);
459 // We only need to check for the overflow in one case:
460 // MIN / -1, and only for signed values.
462 let neg_1 = self.neg_1_literal(span, ty);
463 let min = self.minval_literal(span, ty);
465 let is_neg_1 = self.temp(bool_ty, span);
466 let is_min = self.temp(bool_ty, span);
467 let of = self.temp(bool_ty, span);
469 // this does (rhs == -1) & (lhs == MIN). It could short-circuit instead
471 self.cfg.push_assign(
475 Rvalue::BinaryOp(BinOp::Eq, rhs.to_copy(), neg_1),
477 self.cfg.push_assign(
481 Rvalue::BinaryOp(BinOp::Eq, lhs.to_copy(), min),
484 let is_neg_1 = Operand::Move(is_neg_1);
485 let is_min = Operand::Move(is_min);
486 self.cfg.push_assign(
490 Rvalue::BinaryOp(BinOp::BitAnd, is_neg_1, is_min),
493 block = self.assert(block, Operand::Move(of), false, overflow_err, span);
497 block.and(Rvalue::BinaryOp(op, lhs, rhs))
501 fn limit_capture_mutability(
505 temp_lifetime: Option<region::Scope>,
506 mut block: BasicBlock,
508 region: &'tcx ty::RegionKind,
509 ) -> BlockAnd<Operand<'tcx>> {
512 let source_info = this.source_info(upvar_span);
515 .push(LocalDecl::new_temp(upvar_ty, upvar_span));
521 kind: StatementKind::StorageLive(temp),
525 let arg_place = unpack!(block = this.as_place(block, arg));
527 let mutability = match arg_place {
528 Place::Local(local) => this.local_decls[local].mutability,
529 Place::Projection(box Projection {
530 base: Place::Local(local),
531 elem: ProjectionElem::Deref,
534 if let Some(ClearCrossCrate::Set(BindingForm::RefForGuard)) =
535 this.local_decls[local].is_user_variable
541 "Unexpected capture place",
543 this.local_decls[local].mutability
545 Place::Projection(box Projection {
547 elem: ProjectionElem::Field(upvar_index, _),
549 | Place::Projection(box Projection {
551 Place::Projection(box Projection {
553 elem: ProjectionElem::Field(upvar_index, _),
555 elem: ProjectionElem::Deref,
557 // Not projected from the implicit `self` in a closure.
560 Place::Local(local) => local == Local::new(1),
561 Place::Projection(box Projection {
563 elem: ProjectionElem::Deref,
564 }) => *base == Place::Local(Local::new(1)),
567 "Unexpected capture place"
571 this.upvar_decls.len() > upvar_index.index(),
572 "Unexpected capture place"
574 this.upvar_decls[upvar_index.index()].mutability
576 _ => bug!("Unexpected capture place"),
579 let borrow_kind = match mutability {
580 Mutability::Not => BorrowKind::Unique,
581 Mutability::Mut => BorrowKind::Mut {
582 allow_two_phase_borrow: false,
586 this.cfg.push_assign(
590 Rvalue::Ref(region, borrow_kind, arg_place),
593 // In constants, temp_lifetime is None. We should not need to drop
594 // anything because no values with a destructor can be created in
595 // a constant at this time, even if the type may need dropping.
596 if let Some(temp_lifetime) = temp_lifetime {
597 this.schedule_drop_storage_and_value(
605 block.and(Operand::Move(Place::Local(temp)))
608 // Helper to get a `-1` value of the appropriate type
609 fn neg_1_literal(&mut self, span: Span, ty: Ty<'tcx>) -> Operand<'tcx> {
610 let param_ty = ty::ParamEnv::empty().and(self.hir.tcx().lift_to_global(&ty).unwrap());
611 let bits = self.hir.tcx().layout_of(param_ty).unwrap().size.bits();
612 let n = (!0u128) >> (128 - bits);
613 let literal = ty::Const::from_bits(self.hir.tcx(), n, param_ty);
615 self.literal_operand(span, ty, literal)
618 // Helper to get the minimum value of the appropriate type
619 fn minval_literal(&mut self, span: Span, ty: Ty<'tcx>) -> Operand<'tcx> {
620 assert!(ty.is_signed());
621 let param_ty = ty::ParamEnv::empty().and(self.hir.tcx().lift_to_global(&ty).unwrap());
622 let bits = self.hir.tcx().layout_of(param_ty).unwrap().size.bits();
623 let n = 1 << (bits - 1);
624 let literal = ty::Const::from_bits(self.hir.tcx(), n, param_ty);
626 self.literal_operand(span, ty, literal)