Use existing framework for backward dataflow analyses

src/librustc_codegen_ssa/mir/analyze.rs

@@ -269,7 +269,8 @@ impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> Visitor<'tcx>
 
     fn visit_local(&mut self, &local: &mir::Local, context: PlaceContext, location: Location) {
         match context {
-            PlaceContext::MutatingUse(MutatingUseContext::Call) => {
+            PlaceContext::MutatingUse(MutatingUseContext::Call)
+            | PlaceContext::MutatingUse(MutatingUseContext::Yield) => {
                 self.assign(local, location);
             }
 

src/librustc_middle/mir/visit.rs

@@ -510,7 +510,7 @@ macro_rules! make_mir_visitor {
                         self.visit_operand(value, source_location);
                         self.visit_place(
                             resume_arg,
-                            PlaceContext::MutatingUse(MutatingUseContext::Store),
+                            PlaceContext::MutatingUse(MutatingUseContext::Yield),
                             source_location,
                         );
                     }
@@ -1052,6 +1052,8 @@ pub enum MutatingUseContext {
     AsmOutput,
     /// Destination of a call.
     Call,
+    /// Destination of a yield.
+    Yield,
     /// Being dropped.
     Drop,
     /// Mutable borrow.

src/librustc_mir/borrow_check/mod.rs

@@ -518,7 +518,7 @@ crate struct MirBorrowckCtxt<'cx, 'tcx> {
 impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tcx> {
     type FlowState = Flows<'cx, 'tcx>;
 
-    fn visit_statement(
+    fn visit_statement_before_primary_effect(
         &mut self,
         flow_state: &Flows<'cx, 'tcx>,
         stmt: &'cx Statement<'tcx>,
@@ -607,7 +607,7 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
         }
     }
 
-    fn visit_terminator(
+    fn visit_terminator_before_primary_effect(
         &mut self,
         flow_state: &Flows<'cx, 'tcx>,
         term: &'cx Terminator<'tcx>,
@@ -701,7 +701,7 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
         }
     }
 
-    fn visit_terminator_exit(
+    fn visit_terminator_after_primary_effect(
         &mut self,
         flow_state: &Flows<'cx, 'tcx>,
         term: &'cx Terminator<'tcx>,

src/librustc_mir/borrow_check/type_check/liveness/trace.rs

@@ -408,7 +408,7 @@ impl LivenessContext<'_, '_, '_, 'tcx> {
     /// DROP of some local variable will have an effect -- note that
     /// drops, as they may unwind, are always terminators.
     fn initialized_at_terminator(&mut self, block: BasicBlock, mpi: MovePathIndex) -> bool {
-        self.flow_inits.seek_before(self.body.terminator_loc(block));
+        self.flow_inits.seek_before_primary_effect(self.body.terminator_loc(block));
         self.initialized_at_curr_loc(mpi)
     }
 
@@ -418,7 +418,7 @@ impl LivenessContext<'_, '_, '_, 'tcx> {
     /// **Warning:** Does not account for the result of `Call`
     /// instructions.
     fn initialized_at_exit(&mut self, block: BasicBlock, mpi: MovePathIndex) -> bool {
-        self.flow_inits.seek_after(self.body.terminator_loc(block));
+        self.flow_inits.seek_after_primary_effect(self.body.terminator_loc(block));
         self.initialized_at_curr_loc(mpi)
     }