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//! See docs in `build/expr/mod.rs`.
use rustc_index::{Idx, IndexVec};
use rustc_middle::ty::util::IntTypeExt;
use rustc_target::abi::{Abi, FieldIdx, Primitive};
use crate::build::expr::as_place::PlaceBase;
use crate::build::expr::category::{Category, RvalueFunc};
use crate::build::{BlockAnd, BlockAndExtension, Builder, NeedsTemporary};
use rustc_hir::lang_items::LangItem;
use rustc_middle::middle::region;
use rustc_middle::mir::interpret::Scalar;
use rustc_middle::mir::AssertKind;
use rustc_middle::mir::Place;
use rustc_middle::mir::*;
use rustc_middle::thir::*;
use rustc_middle::ty::cast::{mir_cast_kind, CastTy};
use rustc_middle::ty::layout::IntegerExt;
use rustc_middle::ty::{self, Ty, UpvarArgs};
use rustc_span::Span;
impl<'a, 'tcx> Builder<'a, 'tcx> {
/// Returns an rvalue suitable for use until the end of the current
/// scope expression.
///
/// The operand returned from this function will *not be valid* after
/// an ExprKind::Scope is passed, so please do *not* return it from
/// functions to avoid bad miscompiles.
pub(crate) fn as_local_rvalue(
&mut self,
block: BasicBlock,
expr: &Expr<'tcx>,
) -> BlockAnd<Rvalue<'tcx>> {
let local_scope = self.local_scope();
self.as_rvalue(block, Some(local_scope), expr)
}
/// Compile `expr`, yielding an rvalue.
pub(crate) fn as_rvalue(
&mut self,
mut block: BasicBlock,
scope: Option<region::Scope>,
expr: &Expr<'tcx>,
) -> BlockAnd<Rvalue<'tcx>> {
debug!("expr_as_rvalue(block={:?}, scope={:?}, expr={:?})", block, scope, expr);
let this = self;
let expr_span = expr.span;
let source_info = this.source_info(expr_span);
match expr.kind {
ExprKind::ThreadLocalRef(did) => block.and(Rvalue::ThreadLocalRef(did)),
ExprKind::Scope { region_scope, lint_level, value } => {
let region_scope = (region_scope, source_info);
this.in_scope(region_scope, lint_level, |this| {
this.as_rvalue(block, scope, &this.thir[value])
})
}
ExprKind::Repeat { value, count } => {
if Some(0) == count.try_eval_target_usize(this.tcx, this.param_env) {
this.build_zero_repeat(block, value, scope, source_info)
} else {
let value_operand = unpack!(
block = this.as_operand(
block,
scope,
&this.thir[value],
LocalInfo::Boring,
NeedsTemporary::No
)
);
block.and(Rvalue::Repeat(value_operand, count))
}
}
ExprKind::Binary { op, lhs, rhs } => {
let lhs = unpack!(
block = this.as_operand(
block,
scope,
&this.thir[lhs],
LocalInfo::Boring,
NeedsTemporary::Maybe
)
);
let rhs = unpack!(
block = this.as_operand(
block,
scope,
&this.thir[rhs],
LocalInfo::Boring,
NeedsTemporary::No
)
);
this.build_binary_op(block, op, expr_span, expr.ty, lhs, rhs)
}
ExprKind::Unary { op, arg } => {
let arg = unpack!(
block = this.as_operand(
block,
scope,
&this.thir[arg],
LocalInfo::Boring,
NeedsTemporary::No
)
);
// Check for -MIN on signed integers
if this.check_overflow && op == UnOp::Neg && expr.ty.is_signed() {
let bool_ty = this.tcx.types.bool;
let minval = this.minval_literal(expr_span, expr.ty);
let is_min = this.temp(bool_ty, expr_span);
this.cfg.push_assign(
block,
source_info,
is_min,
Rvalue::BinaryOp(BinOp::Eq, Box::new((arg.to_copy(), minval))),
);
block = this.assert(
block,
Operand::Move(is_min),
false,
AssertKind::OverflowNeg(arg.to_copy()),
expr_span,
);
}
block.and(Rvalue::UnaryOp(op, arg))
}
ExprKind::Box { value } => {
let value = &this.thir[value];
let tcx = this.tcx;
// `exchange_malloc` is unsafe but box is safe, so need a new scope.
let synth_scope = this.new_source_scope(
expr_span,
LintLevel::Inherited,
Some(Safety::BuiltinUnsafe),
);
let synth_info = SourceInfo { span: expr_span, scope: synth_scope };
let size = this.temp(tcx.types.usize, expr_span);
this.cfg.push_assign(
block,
synth_info,
size,
Rvalue::NullaryOp(NullOp::SizeOf, value.ty),
);
let align = this.temp(tcx.types.usize, expr_span);
this.cfg.push_assign(
block,
synth_info,
align,
Rvalue::NullaryOp(NullOp::AlignOf, value.ty),
);
// malloc some memory of suitable size and align:
let exchange_malloc = Operand::function_handle(
tcx,
tcx.require_lang_item(LangItem::ExchangeMalloc, Some(expr_span)),
[],
expr_span,
);
let storage = this.temp(Ty::new_mut_ptr(tcx, tcx.types.u8), expr_span);
let success = this.cfg.start_new_block();
this.cfg.terminate(
block,
synth_info,
TerminatorKind::Call {
func: exchange_malloc,
args: vec![Operand::Move(size), Operand::Move(align)],
destination: storage,
target: Some(success),
unwind: UnwindAction::Continue,
call_source: CallSource::Misc,
fn_span: expr_span,
},
);
this.diverge_from(block);
block = success;
// The `Box<T>` temporary created here is not a part of the HIR,
// and therefore is not considered during generator auto-trait
// determination. See the comment about `box` at `yield_in_scope`.
let result = this.local_decls.push(LocalDecl::new(expr.ty, expr_span));
this.cfg.push(
block,
Statement { source_info, kind: StatementKind::StorageLive(result) },
);
if let Some(scope) = scope {
// schedule a shallow free of that memory, lest we unwind:
this.schedule_drop_storage_and_value(expr_span, scope, result);
}
// Transmute `*mut u8` to the box (thus far, uninitialized):
let box_ = Rvalue::ShallowInitBox(Operand::Move(storage), value.ty);
this.cfg.push_assign(block, source_info, Place::from(result), box_);
// initialize the box contents:
unpack!(
block = this.expr_into_dest(
this.tcx.mk_place_deref(Place::from(result)),
block,
value
)
);
block.and(Rvalue::Use(Operand::Move(Place::from(result))))
}
ExprKind::Cast { source } => {
let source = &this.thir[source];
// Casting an enum to an integer is equivalent to computing the discriminant and casting the
// discriminant. Previously every backend had to repeat the logic for this operation. Now we
// create all the steps directly in MIR with operations all backends need to support anyway.
let (source, ty) = if let ty::Adt(adt_def, ..) = source.ty.kind() && adt_def.is_enum() {
let discr_ty = adt_def.repr().discr_type().to_ty(this.tcx);
let temp = unpack!(block = this.as_temp(block, scope, source, Mutability::Not));
let layout = this.tcx.layout_of(this.param_env.and(source.ty));
let discr = this.temp(discr_ty, source.span);
this.cfg.push_assign(
block,
source_info,
discr,
Rvalue::Discriminant(temp.into()),
);
let (op,ty) = (Operand::Move(discr), discr_ty);
if let Abi::Scalar(scalar) = layout.unwrap().abi
&& !scalar.is_always_valid(&this.tcx)
&& let Primitive::Int(int_width, _signed) = scalar.primitive()
{
let unsigned_ty = int_width.to_ty(this.tcx, false);
let unsigned_place = this.temp(unsigned_ty, expr_span);
this.cfg.push_assign(
block,
source_info,
unsigned_place,
Rvalue::Cast(CastKind::IntToInt, Operand::Copy(discr), unsigned_ty));
let bool_ty = this.tcx.types.bool;
let range = scalar.valid_range(&this.tcx);
let merge_op =
if range.start <= range.end {
BinOp::BitAnd
} else {
BinOp::BitOr
};
let mut comparer = |range: u128, bin_op: BinOp| -> Place<'tcx> {
let range_val =
Const::from_bits(this.tcx, range, ty::ParamEnv::empty().and(unsigned_ty));
let lit_op = this.literal_operand(expr.span, range_val);
let is_bin_op = this.temp(bool_ty, expr_span);
this.cfg.push_assign(
block,
source_info,
is_bin_op,
Rvalue::BinaryOp(bin_op, Box::new((Operand::Copy(unsigned_place), lit_op))),
);
is_bin_op
};
let assert_place = if range.start == 0 {
comparer(range.end, BinOp::Le)
} else {
let start_place = comparer(range.start, BinOp::Ge);
let end_place = comparer(range.end, BinOp::Le);
let merge_place = this.temp(bool_ty, expr_span);
this.cfg.push_assign(
block,
source_info,
merge_place,
Rvalue::BinaryOp(merge_op, Box::new((Operand::Move(start_place), Operand::Move(end_place)))),
);
merge_place
};
this.cfg.push(
block,
Statement {
source_info,
kind: StatementKind::Intrinsic(Box::new(NonDivergingIntrinsic::Assume(
Operand::Move(assert_place),
))),
},
);
}
(op,ty)
} else {
let ty = source.ty;
let source = unpack!(
block = this.as_operand(block, scope, source, LocalInfo::Boring, NeedsTemporary::No)
);
(source, ty)
};
let from_ty = CastTy::from_ty(ty);
let cast_ty = CastTy::from_ty(expr.ty);
debug!("ExprKind::Cast from_ty={from_ty:?}, cast_ty={:?}/{cast_ty:?}", expr.ty,);
let cast_kind = mir_cast_kind(ty, expr.ty);
block.and(Rvalue::Cast(cast_kind, source, expr.ty))
}
ExprKind::PointerCoercion { cast, source } => {
let source = unpack!(
block = this.as_operand(
block,
scope,
&this.thir[source],
LocalInfo::Boring,
NeedsTemporary::No
)
);
block.and(Rvalue::Cast(CastKind::PointerCoercion(cast), source, expr.ty))
}
ExprKind::Array { ref fields } => {
// (*) We would (maybe) be closer to codegen if we
// handled this and other aggregate cases via
// `into()`, not `as_rvalue` -- in that case, instead
// of generating
//
// let tmp1 = ...1;
// let tmp2 = ...2;
// dest = Rvalue::Aggregate(Foo, [tmp1, tmp2])
//
// we could just generate
//
// dest.f = ...1;
// dest.g = ...2;
//
// The problem is that then we would need to:
//
// (a) have a more complex mechanism for handling
// partial cleanup;
// (b) distinguish the case where the type `Foo` has a
// destructor, in which case creating an instance
// as a whole "arms" the destructor, and you can't
// write individual fields; and,
// (c) handle the case where the type Foo has no
// fields. We don't want `let x: ();` to compile
// to the same MIR as `let x = ();`.
// first process the set of fields
let el_ty = expr.ty.sequence_element_type(this.tcx);
let fields: IndexVec<FieldIdx, _> = fields
.into_iter()
.copied()
.map(|f| {
unpack!(
block = this.as_operand(
block,
scope,
&this.thir[f],
LocalInfo::Boring,
NeedsTemporary::Maybe
)
)
})
.collect();
block.and(Rvalue::Aggregate(Box::new(AggregateKind::Array(el_ty)), fields))
}
ExprKind::Tuple { ref fields } => {
// see (*) above
// first process the set of fields
let fields: IndexVec<FieldIdx, _> = fields
.into_iter()
.copied()
.map(|f| {
unpack!(
block = this.as_operand(
block,
scope,
&this.thir[f],
LocalInfo::Boring,
NeedsTemporary::Maybe
)
)
})
.collect();
block.and(Rvalue::Aggregate(Box::new(AggregateKind::Tuple), fields))
}
ExprKind::Closure(box ClosureExpr {
closure_id,
args,
ref upvars,
movability,
ref fake_reads,
}) => {
// Convert the closure fake reads, if any, from `ExprRef` to mir `Place`
// and push the fake reads.
// This must come before creating the operands. This is required in case
// there is a fake read and a borrow of the same path, since otherwise the
// fake read might interfere with the borrow. Consider an example like this
// one:
// ```
// let mut x = 0;
// let c = || {
// &mut x; // mutable borrow of `x`
// match x { _ => () } // fake read of `x`
// };
// ```
//
for (thir_place, cause, hir_id) in fake_reads.into_iter() {
let place_builder =
unpack!(block = this.as_place_builder(block, &this.thir[*thir_place]));
if let Some(mir_place) = place_builder.try_to_place(this) {
this.cfg.push_fake_read(
block,
this.source_info(this.tcx.hir().span(*hir_id)),
*cause,
mir_place,
);
}
}
// see (*) above
let operands: IndexVec<FieldIdx, _> = upvars
.into_iter()
.copied()
.map(|upvar| {
let upvar = &this.thir[upvar];
match Category::of(&upvar.kind) {
// Use as_place to avoid creating a temporary when
// moving a variable into a closure, so that
// borrowck knows which variables to mark as being
// used as mut. This is OK here because the upvar
// expressions have no side effects and act on
// disjoint places.
// This occurs when capturing by copy/move, while
// by reference captures use as_operand
Some(Category::Place) => {
let place = unpack!(block = this.as_place(block, upvar));
this.consume_by_copy_or_move(place)
}
_ => {
// Turn mutable borrow captures into unique
// borrow captures when capturing an immutable
// variable. This is sound because the mutation
// that caused the capture will cause an error.
match upvar.kind {
ExprKind::Borrow {
borrow_kind:
BorrowKind::Mut { kind: MutBorrowKind::Default },
arg,
} => unpack!(
block = this.limit_capture_mutability(
upvar.span,
upvar.ty,
scope,
block,
&this.thir[arg],
)
),
_ => {
unpack!(
block = this.as_operand(
block,
scope,
upvar,
LocalInfo::Boring,
NeedsTemporary::Maybe
)
)
}
}
}
}
})
.collect();
let result = match args {
UpvarArgs::Generator(args) => {
// We implicitly set the discriminant to 0. See
// librustc_mir/transform/deaggregator.rs for details.
let movability = movability.unwrap();
Box::new(AggregateKind::Generator(closure_id.to_def_id(), args, movability))
}
UpvarArgs::Closure(args) => {
Box::new(AggregateKind::Closure(closure_id.to_def_id(), args))
}
};
block.and(Rvalue::Aggregate(result, operands))
}
ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => {
block = unpack!(this.stmt_expr(block, expr, None));
block.and(Rvalue::Use(Operand::Constant(Box::new(ConstOperand {
span: expr_span,
user_ty: None,
const_: Const::zero_sized(this.tcx.types.unit),
}))))
}
ExprKind::OffsetOf { container, fields } => {
block.and(Rvalue::NullaryOp(NullOp::OffsetOf(fields), container))
}
ExprKind::Literal { .. }
| ExprKind::NamedConst { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ZstLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::StaticRef { .. } => {
let constant = this.as_constant(expr);
block.and(Rvalue::Use(Operand::Constant(Box::new(constant))))
}
ExprKind::Yield { .. }
| ExprKind::Block { .. }
| ExprKind::Match { .. }
| ExprKind::If { .. }
| ExprKind::NeverToAny { .. }
| ExprKind::Use { .. }
| ExprKind::Borrow { .. }
| ExprKind::AddressOf { .. }
| ExprKind::Adt { .. }
| ExprKind::Loop { .. }
| ExprKind::LogicalOp { .. }
| ExprKind::Call { .. }
| ExprKind::Field { .. }
| ExprKind::Let { .. }
| ExprKind::Deref { .. }
| ExprKind::Index { .. }
| ExprKind::VarRef { .. }
| ExprKind::UpvarRef { .. }
| ExprKind::Break { .. }
| ExprKind::Continue { .. }
| ExprKind::Return { .. }
| ExprKind::Become { .. }
| ExprKind::InlineAsm { .. }
| ExprKind::PlaceTypeAscription { .. }
| ExprKind::ValueTypeAscription { .. } => {
// these do not have corresponding `Rvalue` variants,
// so make an operand and then return that
debug_assert!(!matches!(
Category::of(&expr.kind),
Some(Category::Rvalue(RvalueFunc::AsRvalue) | Category::Constant)
));
let operand = unpack!(
block =
this.as_operand(block, scope, expr, LocalInfo::Boring, NeedsTemporary::No)
);
block.and(Rvalue::Use(operand))
}
}
}
pub(crate) fn build_binary_op(
&mut self,
mut block: BasicBlock,
op: BinOp,
span: Span,
ty: Ty<'tcx>,
lhs: Operand<'tcx>,
rhs: Operand<'tcx>,
) -> BlockAnd<Rvalue<'tcx>> {
let source_info = self.source_info(span);
let bool_ty = self.tcx.types.bool;
let rvalue = match op {
BinOp::Add | BinOp::Sub | BinOp::Mul if self.check_overflow && ty.is_integral() => {
let result_tup = Ty::new_tup(self.tcx, &[ty, bool_ty]);
let result_value = self.temp(result_tup, span);
self.cfg.push_assign(
block,
source_info,
result_value,
Rvalue::CheckedBinaryOp(op, Box::new((lhs.to_copy(), rhs.to_copy()))),
);
let val_fld = FieldIdx::new(0);
let of_fld = FieldIdx::new(1);
let tcx = self.tcx;
let val = tcx.mk_place_field(result_value, val_fld, ty);
let of = tcx.mk_place_field(result_value, of_fld, bool_ty);
let err = AssertKind::Overflow(op, lhs, rhs);
block = self.assert(block, Operand::Move(of), false, err, span);
Rvalue::Use(Operand::Move(val))
}
BinOp::Shl | BinOp::Shr if self.check_overflow && ty.is_integral() => {
// For an unsigned RHS, the shift is in-range for `rhs < bits`.
// For a signed RHS, `IntToInt` cast to the equivalent unsigned
// type and do that same comparison. Because the type is the
// same size, there's no negative shift amount that ends up
// overlapping with valid ones, thus it catches negatives too.
let (lhs_size, _) = ty.int_size_and_signed(self.tcx);
let rhs_ty = rhs.ty(&self.local_decls, self.tcx);
let (rhs_size, _) = rhs_ty.int_size_and_signed(self.tcx);
let (unsigned_rhs, unsigned_ty) = match rhs_ty.kind() {
ty::Uint(_) => (rhs.to_copy(), rhs_ty),
ty::Int(int_width) => {
let uint_ty = Ty::new_uint(self.tcx, int_width.to_unsigned());
let rhs_temp = self.temp(uint_ty, span);
self.cfg.push_assign(
block,
source_info,
rhs_temp,
Rvalue::Cast(CastKind::IntToInt, rhs.to_copy(), uint_ty),
);
(Operand::Move(rhs_temp), uint_ty)
}
_ => unreachable!("only integers are shiftable"),
};
// This can't overflow because the largest shiftable types are 128-bit,
// which fits in `u8`, the smallest possible `unsigned_ty`.
// (And `from_uint` will `bug!` if that's ever no longer true.)
let lhs_bits = Operand::const_from_scalar(
self.tcx,
unsigned_ty,
Scalar::from_uint(lhs_size.bits(), rhs_size),
span,
);
let inbounds = self.temp(bool_ty, span);
self.cfg.push_assign(
block,
source_info,
inbounds,
Rvalue::BinaryOp(BinOp::Lt, Box::new((unsigned_rhs, lhs_bits))),
);
let overflow_err = AssertKind::Overflow(op, lhs.to_copy(), rhs.to_copy());
block = self.assert(block, Operand::Move(inbounds), true, overflow_err, span);
Rvalue::BinaryOp(op, Box::new((lhs, rhs)))
}
BinOp::Div | BinOp::Rem if ty.is_integral() => {
// Checking division and remainder is more complex, since we 1. always check
// and 2. there are two possible failure cases, divide-by-zero and overflow.
let zero_err = if op == BinOp::Div {
AssertKind::DivisionByZero(lhs.to_copy())
} else {
AssertKind::RemainderByZero(lhs.to_copy())
};
let overflow_err = AssertKind::Overflow(op, lhs.to_copy(), rhs.to_copy());
// Check for / 0
let is_zero = self.temp(bool_ty, span);
let zero = self.zero_literal(span, ty);
self.cfg.push_assign(
block,
source_info,
is_zero,
Rvalue::BinaryOp(BinOp::Eq, Box::new((rhs.to_copy(), zero))),
);
block = self.assert(block, Operand::Move(is_zero), false, zero_err, span);
// We only need to check for the overflow in one case:
// MIN / -1, and only for signed values.
if ty.is_signed() {
let neg_1 = self.neg_1_literal(span, ty);
let min = self.minval_literal(span, ty);
let is_neg_1 = self.temp(bool_ty, span);
let is_min = self.temp(bool_ty, span);
let of = self.temp(bool_ty, span);
// this does (rhs == -1) & (lhs == MIN). It could short-circuit instead
self.cfg.push_assign(
block,
source_info,
is_neg_1,
Rvalue::BinaryOp(BinOp::Eq, Box::new((rhs.to_copy(), neg_1))),
);
self.cfg.push_assign(
block,
source_info,
is_min,
Rvalue::BinaryOp(BinOp::Eq, Box::new((lhs.to_copy(), min))),
);
let is_neg_1 = Operand::Move(is_neg_1);
let is_min = Operand::Move(is_min);
self.cfg.push_assign(
block,
source_info,
of,
Rvalue::BinaryOp(BinOp::BitAnd, Box::new((is_neg_1, is_min))),
);
block = self.assert(block, Operand::Move(of), false, overflow_err, span);
}
Rvalue::BinaryOp(op, Box::new((lhs, rhs)))
}
_ => Rvalue::BinaryOp(op, Box::new((lhs, rhs))),
};
block.and(rvalue)
}
fn build_zero_repeat(
&mut self,
mut block: BasicBlock,
value: ExprId,
scope: Option<region::Scope>,
outer_source_info: SourceInfo,
) -> BlockAnd<Rvalue<'tcx>> {
let this = self;
let value = &this.thir[value];
let elem_ty = value.ty;
if let Some(Category::Constant) = Category::of(&value.kind) {
// Repeating a const does nothing
} else {
// For a non-const, we may need to generate an appropriate `Drop`
let value_operand = unpack!(
block = this.as_operand(block, scope, value, LocalInfo::Boring, NeedsTemporary::No)
);
if let Operand::Move(to_drop) = value_operand {
let success = this.cfg.start_new_block();
this.cfg.terminate(
block,
outer_source_info,
TerminatorKind::Drop {
place: to_drop,
target: success,
unwind: UnwindAction::Continue,
replace: false,
},
);
this.diverge_from(block);
block = success;
}
this.record_operands_moved(&[value_operand]);
}
block.and(Rvalue::Aggregate(Box::new(AggregateKind::Array(elem_ty)), IndexVec::new()))
}
fn limit_capture_mutability(
&mut self,
upvar_span: Span,
upvar_ty: Ty<'tcx>,
temp_lifetime: Option<region::Scope>,
mut block: BasicBlock,
arg: &Expr<'tcx>,
) -> BlockAnd<Operand<'tcx>> {
let this = self;
let source_info = this.source_info(upvar_span);
let temp = this.local_decls.push(LocalDecl::new(upvar_ty, upvar_span));
this.cfg.push(block, Statement { source_info, kind: StatementKind::StorageLive(temp) });
let arg_place_builder = unpack!(block = this.as_place_builder(block, arg));
let mutability = match arg_place_builder.base() {
// We are capturing a path that starts off a local variable in the parent.
// The mutability of the current capture is same as the mutability
// of the local declaration in the parent.
PlaceBase::Local(local) => this.local_decls[local].mutability,
// Parent is a closure and we are capturing a path that is captured
// by the parent itself. The mutability of the current capture
// is same as that of the capture in the parent closure.
PlaceBase::Upvar { .. } => {
let enclosing_upvars_resolved = arg_place_builder.to_place(this);
match enclosing_upvars_resolved.as_ref() {
PlaceRef {
local,
projection: &[ProjectionElem::Field(upvar_index, _), ..],
}
| PlaceRef {
local,
projection:
&[ProjectionElem::Deref, ProjectionElem::Field(upvar_index, _), ..],
} => {
// Not in a closure
debug_assert!(
local == ty::CAPTURE_STRUCT_LOCAL,
"Expected local to be Local(1), found {local:?}"
);
// Not in a closure
debug_assert!(
this.upvars.len() > upvar_index.index(),
"Unexpected capture place, upvars={:#?}, upvar_index={:?}",
this.upvars,
upvar_index
);
this.upvars[upvar_index.index()].mutability
}
_ => bug!("Unexpected capture place"),
}
}
};
let borrow_kind = match mutability {
Mutability::Not => BorrowKind::Mut { kind: MutBorrowKind::ClosureCapture },
Mutability::Mut => BorrowKind::Mut { kind: MutBorrowKind::Default },
};
let arg_place = arg_place_builder.to_place(this);
this.cfg.push_assign(
block,
source_info,
Place::from(temp),
Rvalue::Ref(this.tcx.lifetimes.re_erased, borrow_kind, arg_place),
);
// See the comment in `expr_as_temp` and on the `rvalue_scopes` field for why
// this can be `None`.
if let Some(temp_lifetime) = temp_lifetime {
this.schedule_drop_storage_and_value(upvar_span, temp_lifetime, temp);
}
block.and(Operand::Move(Place::from(temp)))
}
// Helper to get a `-1` value of the appropriate type
fn neg_1_literal(&mut self, span: Span, ty: Ty<'tcx>) -> Operand<'tcx> {
let param_ty = ty::ParamEnv::empty().and(ty);
let size = self.tcx.layout_of(param_ty).unwrap().size;
let literal = Const::from_bits(self.tcx, size.unsigned_int_max(), param_ty);
self.literal_operand(span, literal)
}
// Helper to get the minimum value of the appropriate type
fn minval_literal(&mut self, span: Span, ty: Ty<'tcx>) -> Operand<'tcx> {
assert!(ty.is_signed());
let param_ty = ty::ParamEnv::empty().and(ty);
let bits = self.tcx.layout_of(param_ty).unwrap().size.bits();
let n = 1 << (bits - 1);
let literal = Const::from_bits(self.tcx, n, param_ty);
self.literal_operand(span, literal)
}
}