compiler/rustc_mir_transform/src/remove_storage_markers.rs

   1 //! This pass removes storage markers if they won't be emitted during codegen.
   2
   3 use crate::MirPass;
   4 use rustc_middle::mir::*;
   5 use rustc_middle::ty::TyCtxt;
   6
   7 pub struct RemoveStorageMarkers;
   8
   9 impl<'tcx> MirPass<'tcx> for RemoveStorageMarkers {
  10     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
  11         sess.mir_opt_level() > 0
  12     }
  13
  14     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
  15         if tcx.sess.emit_lifetime_markers() {
  16             return;
  17         }
  18
  19         trace!("Running RemoveStorageMarkers on {:?}", body.source);
  20         for data in body.basic_blocks.as_mut_preserves_cfg() {
  21             data.statements.retain(|statement| match statement.kind {
  22                 StatementKind::StorageLive(..)
  23                 | StatementKind::StorageDead(..)
  24                 | StatementKind::Nop => false,
  25                 _ => true,
  26             })
  27         }
  28     }
  29 }