src/librustc_mir/dataflow/impls/storage_liveness.rs

   1 pub use super::*;
   2
   3 use crate::dataflow::BottomValue;
   4 use crate::dataflow::{self, GenKill};
   5 use crate::util::storage::AlwaysLiveLocals;
   6 use rustc_middle::mir::*;
   7
   8 #[derive(Clone)]
   9 pub struct MaybeStorageLive {
  10     always_live_locals: AlwaysLiveLocals,
  11 }
  12
  13 impl MaybeStorageLive {
  14     pub fn new(always_live_locals: AlwaysLiveLocals) -> Self {
  15         MaybeStorageLive { always_live_locals }
  16     }
  17 }
  18
  19 impl dataflow::AnalysisDomain<'tcx> for MaybeStorageLive {
  20     type Idx = Local;
  21
  22     const NAME: &'static str = "maybe_storage_live";
  23
  24     fn bits_per_block(&self, body: &mir::Body<'tcx>) -> usize {
  25         body.local_decls.len()
  26     }
  27
  28     fn initialize_start_block(&self, body: &mir::Body<'tcx>, on_entry: &mut BitSet<Self::Idx>) {
  29         assert_eq!(body.local_decls.len(), self.always_live_locals.domain_size());
  30         for local in self.always_live_locals.iter() {
  31             on_entry.insert(local);
  32         }
  33
  34         for arg in body.args_iter() {
  35             on_entry.insert(arg);
  36         }
  37     }
  38 }
  39
  40 impl dataflow::GenKillAnalysis<'tcx> for MaybeStorageLive {
  41     fn statement_effect(
  42         &self,
  43         trans: &mut impl GenKill<Self::Idx>,
  44         stmt: &mir::Statement<'tcx>,
  45         _: Location,
  46     ) {
  47         match stmt.kind {
  48             StatementKind::StorageLive(l) => trans.gen(l),
  49             StatementKind::StorageDead(l) => trans.kill(l),
  50             _ => (),
  51         }
  52     }
  53
  54     fn terminator_effect(
  55         &self,
  56         _trans: &mut impl GenKill<Self::Idx>,
  57         _: &mir::Terminator<'tcx>,
  58         _: Location,
  59     ) {
  60         // Terminators have no effect
  61     }
  62
  63     fn call_return_effect(
  64         &self,
  65         _trans: &mut impl GenKill<Self::Idx>,
  66         _block: BasicBlock,
  67         _func: &mir::Operand<'tcx>,
  68         _args: &[mir::Operand<'tcx>],
  69         _return_place: mir::Place<'tcx>,
  70     ) {
  71         // Nothing to do when a call returns successfully
  72     }
  73 }
  74
  75 impl BottomValue for MaybeStorageLive {
  76     /// bottom = dead
  77     const BOTTOM_VALUE: bool = false;
  78 }