Deparameterize Results and ResultsCursor.

They both now only ever contain a `Results<'tcx, A>`.

This means `AnalysisResults` can be removed, as can many
`borrow`/`borrow_mut` calls. Also `Results` no longer needs a
`PhantomData` because `'tcx` is now named by `entry_sets`.

Author: nnethercote

compiler/rustc_mir_dataflow/src/framework/cursor.rs

@@ -2,56 +2,26 @@
 
 use crate::framework::BitSetExt;
 
-use std::borrow::{Borrow, BorrowMut};
 use std::cmp::Ordering;
 
 #[cfg(debug_assertions)]
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::{self, BasicBlock, Location};
 
-use super::{Analysis, Direction, Effect, EffectIndex, EntrySets, Results};
-
-// `AnalysisResults` is needed as an impl such as the following has an unconstrained type
-// parameter:
-// ```
-// impl<'tcx, A, E, R> ResultsCursor<'_, 'tcx, A, R>
-// where
-//     A: Analysis<'tcx>,
-//     E: Borrow<EntrySets<'tcx, A>>,
-//     R: Results<'tcx, A, E>,
-// {}
-// ```
-
-/// A type representing the analysis results consumed by a `ResultsCursor`.
-pub trait AnalysisResults<'tcx, A>: BorrowMut<Results<'tcx, A, Self::EntrySets>>
-where
-    A: Analysis<'tcx>,
-{
-    /// The type containing the entry sets for this `Results` type.
-    ///
-    /// Should be either `EntrySets<'tcx, A>` or `&EntrySets<'tcx, A>`.
-    type EntrySets: Borrow<EntrySets<'tcx, A>>;
-}
-impl<'tcx, A, E> AnalysisResults<'tcx, A> for Results<'tcx, A, E>
-where
-    A: Analysis<'tcx>,
-    E: Borrow<EntrySets<'tcx, A>>,
-{
-    type EntrySets = E;
-}
+use super::{Analysis, Direction, Effect, EffectIndex, Results};
 
 /// Allows random access inspection of the results of a dataflow analysis.
 ///
 /// This cursor only has linear performance within a basic block when its statements are visited in
 /// the same order as the `DIRECTION` of the analysis. In the worst case—when statements are
 /// visited in *reverse* order—performance will be quadratic in the number of statements in the
 /// block. The order in which basic blocks are inspected has no impact on performance.
-pub struct ResultsCursor<'mir, 'tcx, A, R = Results<'tcx, A>>
+pub struct ResultsCursor<'mir, 'tcx, A>
 where
     A: Analysis<'tcx>,
 {
     body: &'mir mir::Body<'tcx>,
-    results: R,
+    results: Results<'tcx, A>,
     state: A::Domain,
 
     pos: CursorPosition,
@@ -65,7 +35,7 @@ where
     reachable_blocks: BitSet<BasicBlock>,
 }
 
-impl<'mir, 'tcx, A, R> ResultsCursor<'mir, 'tcx, A, R>
+impl<'mir, 'tcx, A> ResultsCursor<'mir, 'tcx, A>
 where
     A: Analysis<'tcx>,
 {
@@ -80,19 +50,13 @@ where
     }
 
     /// Unwraps this cursor, returning the underlying `Results`.
-    pub fn into_results(self) -> R {
+    pub fn into_results(self) -> Results<'tcx, A> {
         self.results
     }
-}
 
-impl<'mir, 'tcx, A, R> ResultsCursor<'mir, 'tcx, A, R>
-where
-    A: Analysis<'tcx>,
-    R: AnalysisResults<'tcx, A>,
-{
     /// Returns a new cursor that can inspect `results`.
-    pub fn new(body: &'mir mir::Body<'tcx>, results: R) -> Self {
-        let bottom_value = results.borrow().analysis.bottom_value(body);
+    pub fn new(body: &'mir mir::Body<'tcx>, results: Results<'tcx, A>) -> Self {
+        let bottom_value = results.analysis.bottom_value(body);
         ResultsCursor {
             body,
             results,
@@ -117,23 +81,23 @@ where
     }
 
     /// Returns the underlying `Results`.
-    pub fn results(&self) -> &Results<'tcx, A, R::EntrySets> {
-        self.results.borrow()
+    pub fn results(&self) -> &Results<'tcx, A> {
+        &self.results
     }
 
     /// Returns the underlying `Results`.
-    pub fn mut_results(&mut self) -> &mut Results<'tcx, A, R::EntrySets> {
-        self.results.borrow_mut()
+    pub fn mut_results(&mut self) -> &mut Results<'tcx, A> {
+        &mut self.results
     }
 
     /// Returns the `Analysis` used to generate the underlying `Results`.
     pub fn analysis(&self) -> &A {
-        &self.results.borrow().analysis
+        &self.results.analysis
     }
 
     /// Returns the `Analysis` used to generate the underlying `Results`.
     pub fn mut_analysis(&mut self) -> &mut A {
-        &mut self.results.borrow_mut().analysis
+        &mut self.results.analysis
     }
 
     /// Resets the cursor to hold the entry set for the given basic block.
@@ -145,7 +109,7 @@ where
         #[cfg(debug_assertions)]
         assert!(self.reachable_blocks.contains(block));
 
-        self.state.clone_from(self.results.borrow().entry_set_for_block(block));
+        self.state.clone_from(self.results.entry_set_for_block(block));
         self.pos = CursorPosition::block_entry(block);
         self.state_needs_reset = false;
     }
@@ -234,11 +198,10 @@ where
             )
         };
 
-        let analysis = &mut self.results.borrow_mut().analysis;
         let target_effect_index = effect.at_index(target.statement_index);
 
         A::Direction::apply_effects_in_range(
-            analysis,
+            &mut self.results.analysis,
             &mut self.state,
             target.block,
             block_data,
@@ -254,12 +217,12 @@ where
     /// This can be used, e.g., to apply the call return effect directly to the cursor without
     /// creating an extra copy of the dataflow state.
     pub fn apply_custom_effect(&mut self, f: impl FnOnce(&mut A, &mut A::Domain)) {
-        f(&mut self.results.borrow_mut().analysis, &mut self.state);
+        f(&mut self.results.analysis, &mut self.state);
         self.state_needs_reset = true;
     }
 }
 
-impl<'mir, 'tcx, A, R> ResultsCursor<'mir, 'tcx, A, R>
+impl<'mir, 'tcx, A> ResultsCursor<'mir, 'tcx, A>
 where
     A: crate::GenKillAnalysis<'tcx>,
     A::Domain: BitSetExt<A::Idx>,

compiler/rustc_mir_dataflow/src/framework/engine.rs

@@ -5,9 +5,7 @@ use crate::errors::{
 };
 use crate::framework::BitSetExt;
 
-use std::borrow::Borrow;
 use std::ffi::OsString;
-use std::marker::PhantomData;
 use std::path::PathBuf;
 
 use rustc_ast as ast;
@@ -32,31 +30,29 @@ pub type EntrySets<'tcx, A> = IndexVec<BasicBlock, <A as AnalysisDomain<'tcx>>::
 
 /// A dataflow analysis that has converged to fixpoint.
 #[derive(Clone)]
-pub struct Results<'tcx, A, E = EntrySets<'tcx, A>>
+pub struct Results<'tcx, A>
 where
     A: Analysis<'tcx>,
 {
     pub analysis: A,
-    pub(super) entry_sets: E,
-    pub(super) _marker: PhantomData<&'tcx ()>,
+    pub(super) entry_sets: EntrySets<'tcx, A>,
 }
 
-impl<'tcx, A, E> Results<'tcx, A, E>
+impl<'tcx, A> Results<'tcx, A>
 where
     A: Analysis<'tcx>,
-    E: Borrow<EntrySets<'tcx, A>>,
 {
     /// Creates a `ResultsCursor` that can inspect these `Results`.
     pub fn into_results_cursor<'mir>(
         self,
         body: &'mir mir::Body<'tcx>,
-    ) -> ResultsCursor<'mir, 'tcx, A, Self> {
+    ) -> ResultsCursor<'mir, 'tcx, A> {
         ResultsCursor::new(body, self)
     }
 
     /// Gets the dataflow state for the given block.
     pub fn entry_set_for_block(&self, block: BasicBlock) -> &A::Domain {
-        &self.entry_sets.borrow()[block]
+        &self.entry_sets[block]
     }
 
     pub fn visit_with<'mir>(
@@ -242,7 +238,7 @@ where
             );
         }
 
-        let results = Results { analysis, entry_sets, _marker: PhantomData };
+        let results = Results { analysis, entry_sets };
 
         if tcx.sess.opts.unstable_opts.dump_mir_dataflow {
             let (res, results) = write_graphviz_results(tcx, body, results, pass_name);

compiler/rustc_mir_dataflow/src/framework/mod.rs

@@ -47,7 +47,7 @@ mod visitor;
 
 pub use self::cursor::ResultsCursor;
 pub use self::direction::{Backward, Direction, Forward};
-pub use self::engine::{Engine, EntrySets, Results};
+pub use self::engine::{Engine, Results};
 pub use self::lattice::{JoinSemiLattice, MaybeReachable};
 pub use self::visitor::{visit_results, ResultsVisitable, ResultsVisitor};
 

compiler/rustc_mir_dataflow/src/framework/tests.rs

@@ -267,8 +267,7 @@ fn test_cursor<D: Direction>(analysis: MockAnalysis<'_, D>) {
     let body = analysis.body;
 
     let mut cursor =
-        Results { entry_sets: analysis.mock_entry_sets(), analysis, _marker: PhantomData }
-            .into_results_cursor(body);
+        Results { entry_sets: analysis.mock_entry_sets(), analysis }.into_results_cursor(body);
 
     cursor.allow_unreachable();
 

compiler/rustc_mir_dataflow/src/framework/visitor.rs

@@ -1,8 +1,6 @@
-use std::borrow::Borrow;
-
 use rustc_middle::mir::{self, BasicBlock, Location};
 
-use super::{Analysis, Direction, EntrySets, Results};
+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.
@@ -143,10 +141,9 @@ pub trait ResultsVisitable<'tcx> {
     );
 }
 
-impl<'tcx, A, E> ResultsVisitable<'tcx> for Results<'tcx, A, E>
+impl<'tcx, A> ResultsVisitable<'tcx> for Results<'tcx, A>
 where
     A: Analysis<'tcx>,
-    E: Borrow<EntrySets<'tcx, A>>,
 {
     type FlowState = A::Domain;