rust/compiler/rustc_mir_transform/src/deaggregator.rs
2023-02-02 23:20:27 +00:00

49 lines
1.6 KiB
Rust

use crate::util::expand_aggregate;
use crate::MirPass;
use rustc_hir::def::DefKind;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
pub struct Deaggregator;
impl<'tcx> MirPass<'tcx> for Deaggregator {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
for bb in basic_blocks {
bb.expand_statements(|stmt| {
// FIXME(eddyb) don't match twice on `stmt.kind` (post-NLL).
let StatementKind::Assign(box (
_, Rvalue::Aggregate(box ref kind, _))
) = stmt.kind else { return None };
// FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
if let AggregateKind::Array(_) = kind {
return None;
}
if let AggregateKind::Adt(def_id, ..) = kind
&& matches!(tcx.def_kind(def_id), DefKind::Enum)
{
return None;
}
let stmt = stmt.replace_nop();
let source_info = stmt.source_info;
let StatementKind::Assign(box (lhs, Rvalue::Aggregate(kind, operands))) = stmt.kind else {
bug!();
};
Some(expand_aggregate(
lhs,
operands.into_iter().map(|op| {
let ty = op.ty(&body.local_decls, tcx);
(op, ty)
}),
*kind,
source_info,
tcx,
))
});
}
}
}