73 lines
2.6 KiB
Rust
73 lines
2.6 KiB
Rust
use rustc_index::vec::Idx;
|
|
use rustc_middle::mir::*;
|
|
use rustc_middle::ty::{Ty, TyCtxt};
|
|
use rustc_target::abi::VariantIdx;
|
|
|
|
use std::convert::TryFrom;
|
|
use std::iter::TrustedLen;
|
|
|
|
/// Expand `lhs = Rvalue::Aggregate(kind, operands)` into assignments to the fields.
|
|
///
|
|
/// Produces something like
|
|
///
|
|
/// (lhs as Variant).field0 = arg0; // We only have a downcast if this is an enum
|
|
/// (lhs as Variant).field1 = arg1;
|
|
/// discriminant(lhs) = variant_index; // If lhs is an enum or generator.
|
|
pub fn expand_aggregate<'tcx>(
|
|
mut lhs: Place<'tcx>,
|
|
operands: impl Iterator<Item = (Operand<'tcx>, Ty<'tcx>)> + TrustedLen,
|
|
kind: AggregateKind<'tcx>,
|
|
source_info: SourceInfo,
|
|
tcx: TyCtxt<'tcx>,
|
|
) -> impl Iterator<Item = Statement<'tcx>> + TrustedLen {
|
|
let mut set_discriminant = None;
|
|
let active_field_index = match kind {
|
|
AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => {
|
|
if adt_def.is_enum() {
|
|
set_discriminant = Some(Statement {
|
|
kind: StatementKind::SetDiscriminant { place: box (lhs), variant_index },
|
|
source_info,
|
|
});
|
|
lhs = tcx.mk_place_downcast(lhs, adt_def, variant_index);
|
|
}
|
|
active_field_index
|
|
}
|
|
AggregateKind::Generator(..) => {
|
|
// Right now we only support initializing generators to
|
|
// variant 0 (Unresumed).
|
|
let variant_index = VariantIdx::new(0);
|
|
set_discriminant = Some(Statement {
|
|
kind: StatementKind::SetDiscriminant { place: box (lhs), variant_index },
|
|
source_info,
|
|
});
|
|
|
|
// Operands are upvars stored on the base place, so no
|
|
// downcast is necessary.
|
|
|
|
None
|
|
}
|
|
_ => None,
|
|
};
|
|
|
|
operands
|
|
.enumerate()
|
|
.map(move |(i, (op, ty))| {
|
|
let lhs_field = if let AggregateKind::Array(_) = kind {
|
|
let offset = u64::try_from(i).unwrap();
|
|
tcx.mk_place_elem(
|
|
lhs,
|
|
ProjectionElem::ConstantIndex {
|
|
offset,
|
|
min_length: offset + 1,
|
|
from_end: false,
|
|
},
|
|
)
|
|
} else {
|
|
let field = Field::new(active_field_index.unwrap_or(i));
|
|
tcx.mk_place_field(lhs, field, ty)
|
|
};
|
|
Statement { source_info, kind: StatementKind::Assign(box (lhs_field, Rvalue::Use(op))) }
|
|
})
|
|
.chain(set_discriminant)
|
|
}
|