MIR move elimination [3/6]: PreciseLiveness

compiler/rustc_attr_ir/src/data_structures.rs

@@ -592,6 +592,7 @@ pub enum RustcDumpLayoutKind {
 #[derive(Clone, Debug, StableHash, Encodable, Decodable, PrintAttribute, PartialEq, Eq)]
 pub enum RustcMirKind {
     PrettyLiveLocals,
+    PrettyPreciseLiveness,
     PrettyTransitiveLiveLocals,
     PeekMaybeInit,
     PeekMaybeUninit,

compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs

@@ -630,6 +630,10 @@ impl CombineAttributeParser for RustcMirParser {
                             cx.expect_no_args(mi.args())?;
                             Some(RustcMirKind::PrettyLiveLocals)
                         }
+                        sym::rustc_pretty_precise_liveness => {
+                            cx.expect_no_args(mi.args())?;
+                            Some(RustcMirKind::PrettyPreciseLiveness)
+                        }
                         sym::rustc_pretty_transitive_live_locals => {
                             cx.expect_no_args(mi.args())?;
                             Some(RustcMirKind::PrettyTransitiveLiveLocals)

compiler/rustc_mir_dataflow/src/framework/direction.rs

@@ -127,6 +127,8 @@ impl Direction for Backward {
             analysis.apply_primary_statement_effect(state, stmt, loc);
             vis.visit_after_primary_statement_effect(state, stmt, loc);
         }
+
+        vis.visit_block_exit(state, block);
     }
 }
 
@@ -242,5 +244,7 @@ impl Direction for Forward {
         vis.visit_after_early_terminator_effect(state, term, loc);
         analysis.apply_primary_terminator_effect(state, term, loc);
         vis.visit_after_primary_terminator_effect(state, term, loc);
+
+        vis.visit_block_exit(state, block);
     }
 }

compiler/rustc_mir_dataflow/src/framework/visitor.rs

@@ -34,6 +34,13 @@ pub trait ResultsVisitor<'tcx, A>
 where
     A: Analysis<'tcx>,
 {
+    /// Called after all effects in a block have been applied in the direction
+    /// of the analysis.
+    ///
+    /// In a forwards analysis, `state` is from the block's end. In a backwards
+    /// analysis, `state` is from the block's start.
+    fn visit_block_exit(&mut self, _state: &A::Domain, _block: BasicBlock) {}
+
     /// Called after the "early" effect of the given statement is applied to `state`.
     fn visit_after_early_statement_effect(
         &mut self,

compiler/rustc_mir_dataflow/src/impls/mod.rs

@@ -1,6 +1,7 @@
 mod borrowed_locals;
 mod initialized;
 mod liveness;
+mod precise_liveness;
 mod storage_liveness;
 
 pub use self::borrowed_locals::{MaybeBorrowedLocals, borrowed_locals};
@@ -11,6 +12,10 @@ pub use self::initialized::{
 pub use self::liveness::{
     DefUse, LivenessTransferFunction, MaybeLiveLocals, MaybeTransitiveLiveLocals,
 };
+pub use self::precise_liveness::{
+    SplitPointEffect, SplitPointIndex, VisitAllocatedLocalsWith, VisitDeallocatedLocalsWith,
+    dump_liveness_matrix, liveness_matrix,
+};
 pub use self::storage_liveness::{
     MaybeRequiresStorage, MaybeStorageDead, MaybeStorageLive, always_storage_live_locals,
 };