1 files changed, 0 insertions, 78 deletions
diff --git a/compiler/rustc_middle/src/mir/predecessors.rs b/compiler/rustc_middle/src/mir/predecessors.rs
deleted file mode 100644
index 5f1fadaf3..000000000
--- a/compiler/rustc_middle/src/mir/predecessors.rs
+++ /dev/null
@@ -1,78 +0,0 @@
-//! Lazily compute the reverse control-flow graph for the MIR.
-
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync::OnceCell;
-use rustc_index::vec::IndexVec;
-use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
-use smallvec::SmallVec;
-
-use crate::mir::{BasicBlock, BasicBlockData};
-
-// Typically 95%+ of basic blocks have 4 or fewer predecessors.
-pub type Predecessors = IndexVec<BasicBlock, SmallVec<[BasicBlock; 4]>>;
-
-#[derive(Clone, Debug)]
-pub(super) struct PredecessorCache {
-    cache: OnceCell<Predecessors>,
-}
-
-impl PredecessorCache {
-    #[inline]
-    pub(super) fn new() -> Self {
-        PredecessorCache { cache: OnceCell::new() }
-    }
-
-    /// Invalidates the predecessor cache.
-    #[inline]
-    pub(super) fn invalidate(&mut self) {
-        // Invalidating the predecessor cache requires mutating the MIR, which in turn requires a
-        // unique reference (`&mut`) to the `mir::Body`. Because of this, we can assume that all
-        // callers of `invalidate` have a unique reference to the MIR and thus to the predecessor
-        // cache. This means we never need to do synchronization when `invalidate` is called, we can
-        // simply reinitialize the `OnceCell`.
-        self.cache = OnceCell::new();
-    }
-
-    /// Returns the predecessor graph for this MIR.
-    #[inline]
-    pub(super) fn compute(
-        &self,
-        basic_blocks: &IndexVec<BasicBlock, BasicBlockData<'_>>,
-    ) -> &Predecessors {
-        self.cache.get_or_init(|| {
-            let mut preds = IndexVec::from_elem(SmallVec::new(), basic_blocks);
-            for (bb, data) in basic_blocks.iter_enumerated() {
-                if let Some(term) = &data.terminator {
-                    for succ in term.successors() {
-                        preds[succ].push(bb);
-                    }
-                }
-            }
-
-            preds
-        })
-    }
-}
-
-impl<S: Encoder> Encodable<S> for PredecessorCache {
-    #[inline]
-    fn encode(&self, _s: &mut S) {}
-}
-
-impl<D: Decoder> Decodable<D> for PredecessorCache {
-    #[inline]
-    fn decode(_: &mut D) -> Self {
-        Self::new()
-    }
-}
-
-impl<CTX> HashStable<CTX> for PredecessorCache {
-    #[inline]
-    fn hash_stable(&self, _: &mut CTX, _: &mut StableHasher) {
-        // do nothing
-    }
-}
-
-TrivialTypeTraversalAndLiftImpls! {
-    PredecessorCache,
-}