compiler/rustc_mir_transform/src/deaggregator.rs

   1 use crate::util::expand_aggregate;
   2 use crate::MirPass;
   3 use rustc_middle::mir::*;
   4 use rustc_middle::ty::TyCtxt;
   5
   6 pub struct Deaggregator;
   7
   8 impl<'tcx> MirPass<'tcx> for Deaggregator {
   9     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
  10         let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
  11         for bb in basic_blocks {
  12             bb.expand_statements(|stmt| {
  13                 // FIXME(eddyb) don't match twice on `stmt.kind` (post-NLL).
  14                 match stmt.kind {
  15                     // FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
  16                     StatementKind::Assign(box (
  17                         _,
  18                         Rvalue::Aggregate(box AggregateKind::Array(_), _),
  19                     )) => {
  20                         return None;
  21                     }
  22                     StatementKind::Assign(box (_, Rvalue::Aggregate(_, _))) => {}
  23                     _ => return None,
  24                 }
  25
  26                 let stmt = stmt.replace_nop();
  27                 let source_info = stmt.source_info;
  28                 let StatementKind::Assign(box (lhs, Rvalue::Aggregate(kind, operands))) = stmt.kind else {
  29                     bug!();
  30                 };
  31
  32                 Some(expand_aggregate(
  33                     lhs,
  34                     operands.into_iter().map(|op| {
  35                         let ty = op.ty(&body.local_decls, tcx);
  36                         (op, ty)
  37                     }),
  38                     *kind,
  39                     source_info,
  40                     tcx,
  41                 ))
  42             });
  43         }
  44     }
  45 }