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, local_decls) = body.basic_blocks_and_local_decls_mut();
  15         let local_decls = &*local_decls;
  16         for bb in basic_blocks {
  17             bb.expand_statements(|stmt| {
  18                 // FIXME(eddyb) don't match twice on `stmt.kind` (post-NLL).
  19                 match stmt.kind {
  20                     // FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
  21                     StatementKind::Assign(box (
  22                         _,
  23                         Rvalue::Aggregate(box AggregateKind::Array(_), _),
  24                     )) => {
  25                         return None;
  26                     }
  27                     StatementKind::Assign(box (_, Rvalue::Aggregate(_, _))) => {}
  28                     _ => return None,
  29                 }
  30
  31                 let stmt = stmt.replace_nop();
  32                 let source_info = stmt.source_info;
  33                 let StatementKind::Assign(box (lhs, Rvalue::Aggregate(kind, operands))) = stmt.kind else {
  34                     bug!();
  35                 };
  36
  37                 Some(expand_aggregate(
  38                     lhs,
  39                     operands.into_iter().map(|op| {
  40                         let ty = op.ty(local_decls, tcx);
  41                         (op, ty)
  42                     }),
  43                     *kind,
  44                     source_info,
  45                     tcx,
  46                 ))
  47             });
  48         }
  49     }
  50 }