1 files changed, 187 insertions, 0 deletions
diff --git a/compiler/rustc_mir_dataflow/src/framework/visitor.rs b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
new file mode 100644
index 000000000..75b4e150a
--- /dev/null
+++ b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
@@ -0,0 +1,187 @@
+use rustc_middle::mir::{self, BasicBlock, Location};
+
+use super::{Analysis, Direction, Results};
+
+/// Calls the corresponding method in `ResultsVisitor` for every location in a `mir::Body` with the
+/// dataflow state at that location.
+pub fn visit_results<'mir, 'tcx, F, V>(
+    body: &'mir mir::Body<'tcx>,
+    blocks: impl IntoIterator<Item = BasicBlock>,
+    results: &V,
+    vis: &mut impl ResultsVisitor<'mir, 'tcx, FlowState = F>,
+) where
+    V: ResultsVisitable<'tcx, FlowState = F>,
+{
+    let mut state = results.new_flow_state(body);
+
+    #[cfg(debug_assertions)]
+    let reachable_blocks = mir::traversal::reachable_as_bitset(body);
+
+    for block in blocks {
+        #[cfg(debug_assertions)]
+        assert!(reachable_blocks.contains(block));
+
+        let block_data = &body[block];
+        V::Direction::visit_results_in_block(&mut state, block, block_data, results, vis);
+    }
+}
+
+pub trait ResultsVisitor<'mir, 'tcx> {
+    type FlowState;
+
+    fn visit_block_start(
+        &mut self,
+        _state: &Self::FlowState,
+        _block_data: &'mir mir::BasicBlockData<'tcx>,
+        _block: BasicBlock,
+    ) {
+    }
+
+    /// Called with the `before_statement_effect` of the given statement applied to `state` but not
+    /// its `statement_effect`.
+    fn visit_statement_before_primary_effect(
+        &mut self,
+        _state: &Self::FlowState,
+        _statement: &'mir mir::Statement<'tcx>,
+        _location: Location,
+    ) {
+    }
+
+    /// Called with both the `before_statement_effect` and the `statement_effect` of the given
+    /// statement applied to `state`.
+    fn visit_statement_after_primary_effect(
+        &mut self,
+        _state: &Self::FlowState,
+        _statement: &'mir mir::Statement<'tcx>,
+        _location: Location,
+    ) {
+    }
+
+    /// Called with the `before_terminator_effect` of the given terminator applied to `state` but not
+    /// its `terminator_effect`.
+    fn visit_terminator_before_primary_effect(
+        &mut self,
+        _state: &Self::FlowState,
+        _terminator: &'mir mir::Terminator<'tcx>,
+        _location: Location,
+    ) {
+    }
+
+    /// Called with both the `before_terminator_effect` and the `terminator_effect` of the given
+    /// terminator applied to `state`.
+    ///
+    /// The `call_return_effect` (if one exists) will *not* be applied to `state`.
+    fn visit_terminator_after_primary_effect(
+        &mut self,
+        _state: &Self::FlowState,
+        _terminator: &'mir mir::Terminator<'tcx>,
+        _location: Location,
+    ) {
+    }
+
+    fn visit_block_end(
+        &mut self,
+        _state: &Self::FlowState,
+        _block_data: &'mir mir::BasicBlockData<'tcx>,
+        _block: BasicBlock,
+    ) {
+    }
+}
+
+/// Things that can be visited by a `ResultsVisitor`.
+///
+/// This trait exists so that we can visit the results of multiple dataflow analyses simultaneously.
+/// DO NOT IMPLEMENT MANUALLY. Instead, use the `impl_visitable` macro below.
+pub trait ResultsVisitable<'tcx> {
+    type Direction: Direction;
+    type FlowState;
+
+    /// Creates an empty `FlowState` to hold the transient state for these dataflow results.
+    ///
+    /// The value of the newly created `FlowState` will be overwritten by `reset_to_block_entry`
+    /// before it can be observed by a `ResultsVisitor`.
+    fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState;
+
+    fn reset_to_block_entry(&self, state: &mut Self::FlowState, block: BasicBlock);
+
+    fn reconstruct_before_statement_effect(
+        &self,
+        state: &mut Self::FlowState,
+        statement: &mir::Statement<'tcx>,
+        location: Location,
+    );
+
+    fn reconstruct_statement_effect(
+        &self,
+        state: &mut Self::FlowState,
+        statement: &mir::Statement<'tcx>,
+        location: Location,
+    );
+
+    fn reconstruct_before_terminator_effect(
+        &self,
+        state: &mut Self::FlowState,
+        terminator: &mir::Terminator<'tcx>,
+        location: Location,
+    );
+
+    fn reconstruct_terminator_effect(
+        &self,
+        state: &mut Self::FlowState,
+        terminator: &mir::Terminator<'tcx>,
+        location: Location,
+    );
+}
+
+impl<'tcx, A> ResultsVisitable<'tcx> for Results<'tcx, A>
+where
+    A: Analysis<'tcx>,
+{
+    type FlowState = A::Domain;
+
+    type Direction = A::Direction;
+
+    fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState {
+        self.analysis.bottom_value(body)
+    }
+
+    fn reset_to_block_entry(&self, state: &mut Self::FlowState, block: BasicBlock) {
+        state.clone_from(&self.entry_set_for_block(block));
+    }
+
+    fn reconstruct_before_statement_effect(
+        &self,
+        state: &mut Self::FlowState,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.analysis.apply_before_statement_effect(state, stmt, loc);
+    }
+
+    fn reconstruct_statement_effect(
+        &self,
+        state: &mut Self::FlowState,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.analysis.apply_statement_effect(state, stmt, loc);
+    }
+
+    fn reconstruct_before_terminator_effect(
+        &self,
+        state: &mut Self::FlowState,
+        term: &mir::Terminator<'tcx>,
+        loc: Location,
+    ) {
+        self.analysis.apply_before_terminator_effect(state, term, loc);
+    }
+
+    fn reconstruct_terminator_effect(
+        &self,
+        state: &mut Self::FlowState,
+        term: &mir::Terminator<'tcx>,
+        loc: Location,
+    ) {
+        self.analysis.apply_terminator_effect(state, term, loc);
+    }
+}