Rollup merge of #140234 - nnethercote:separate-Analysis-and-Results, r=davidtwco

Separate dataflow analysis and results

`Analysis` gets put into `Results` with `EntryStates`, by `iterate_to_fixpoint`. This has two problems:
- `Results` is passed various places where only `Analysis` is needed.
- `EntryStates` is passed around mutably everywhere even though it is immutable.

This commit mostly separates `Analysis` from `Results` and fixes these two problems.

r? `@davidtwco`

1 files changed, 14 insertions, 12 deletions

diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 44af1b76539..1afbb83b963 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -47,7 +47,7 @@ use rustc_mir_dataflow::impls::{
 use rustc_mir_dataflow::move_paths::{
     InitIndex, InitLocation, LookupResult, MoveData, MovePathIndex,
 };
-use rustc_mir_dataflow::{Analysis, EntryStates, Results, ResultsVisitor, visit_results};
+use rustc_mir_dataflow::{Analysis, Results, ResultsVisitor, visit_results};
 use rustc_session::lint::builtin::{TAIL_EXPR_DROP_ORDER, UNUSED_MUT};
 use rustc_span::{ErrorGuaranteed, Span, Symbol};
 use smallvec::SmallVec;
@@ -461,11 +461,13 @@ fn do_mir_borrowck<'tcx>(
     // Compute and report region errors, if any.
     mbcx.report_region_errors(nll_errors);
 
-    let mut flow_results = get_flow_results(tcx, body, &move_data, &borrow_set, &regioncx);
+    let (mut flow_analysis, flow_entry_states) =
+        get_flow_results(tcx, body, &move_data, &borrow_set, &regioncx);
     visit_results(
         body,
         traversal::reverse_postorder(body).map(|(bb, _)| bb),
-        &mut flow_results,
+        &mut flow_analysis,
+        &flow_entry_states,
         &mut mbcx,
     );
 
@@ -525,7 +527,7 @@ fn get_flow_results<'a, 'tcx>(
     move_data: &'a MoveData<'tcx>,
     borrow_set: &'a BorrowSet<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
-) -> Results<'tcx, Borrowck<'a, 'tcx>> {
+) -> (Borrowck<'a, 'tcx>, Results<BorrowckDomain>) {
     // We compute these three analyses individually, but them combine them into
     // a single results so that `mbcx` can visit them all together.
     let borrows = Borrows::new(tcx, body, regioncx, borrow_set).iterate_to_fixpoint(
@@ -550,14 +552,14 @@ fn get_flow_results<'a, 'tcx>(
         ever_inits: ever_inits.analysis,
     };
 
-    assert_eq!(borrows.entry_states.len(), uninits.entry_states.len());
-    assert_eq!(borrows.entry_states.len(), ever_inits.entry_states.len());
-    let entry_states: EntryStates<'_, Borrowck<'_, '_>> =
-        itertools::izip!(borrows.entry_states, uninits.entry_states, ever_inits.entry_states)
+    assert_eq!(borrows.results.len(), uninits.results.len());
+    assert_eq!(borrows.results.len(), ever_inits.results.len());
+    let results: Results<_> =
+        itertools::izip!(borrows.results, uninits.results, ever_inits.results)
             .map(|(borrows, uninits, ever_inits)| BorrowckDomain { borrows, uninits, ever_inits })
             .collect();
 
-    Results { analysis, entry_states }
+    (analysis, results)
 }
 
 pub(crate) struct BorrowckInferCtxt<'tcx> {
@@ -705,7 +707,7 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
 impl<'a, 'tcx> ResultsVisitor<'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a, '_, 'tcx> {
     fn visit_after_early_statement_effect(
         &mut self,
-        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
+        _analysis: &mut Borrowck<'a, 'tcx>,
         state: &BorrowckDomain,
         stmt: &Statement<'tcx>,
         location: Location,
@@ -781,7 +783,7 @@ impl<'a, 'tcx> ResultsVisitor<'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a,
 
     fn visit_after_early_terminator_effect(
         &mut self,
-        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
+        _analysis: &mut Borrowck<'a, 'tcx>,
         state: &BorrowckDomain,
         term: &Terminator<'tcx>,
         loc: Location,
@@ -901,7 +903,7 @@ impl<'a, 'tcx> ResultsVisitor<'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a,
 
     fn visit_after_primary_terminator_effect(
         &mut self,
-        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
+        _analysis: &mut Borrowck<'a, 'tcx>,
         state: &BorrowckDomain,
         term: &Terminator<'tcx>,
         loc: Location,