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 phase_change(&self) -> Option<MirPhase> {
  10         Some(MirPhase::Deaggregated)
  11     }
  12
  13     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
  14         let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
  15         for bb in basic_blocks {
  16             bb.expand_statements(|stmt| {
  17                 // FIXME(eddyb) don't match twice on `stmt.kind` (post-NLL).
  18                 match stmt.kind {
  19                     // FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
  20                     StatementKind::Assign(box (
  21                         _,
  22                         Rvalue::Aggregate(box AggregateKind::Array(_), _),
  23                     )) => {
  24                         return None;
  25                     }
  26                     StatementKind::Assign(box (_, Rvalue::Aggregate(_, _))) => {}
  27                     _ => return None,
  28                 }
  29
  30                 let stmt = stmt.replace_nop();
  31                 let source_info = stmt.source_info;
  32                 let StatementKind::Assign(box (lhs, Rvalue::Aggregate(kind, operands))) = stmt.kind else {
  33                     bug!();
  34                 };
  35
  36                 Some(expand_aggregate(
  37                     lhs,
  38                     operands.into_iter().map(|op| {
  39                         let ty = op.ty(&body.local_decls, tcx);
  40                         (op, ty)
  41                     }),
  42                     *kind,
  43                     source_info,
  44                     tcx,
  45                 ))
  46             });
  47         }
  48     }
  49 }