OwnershipUtils: let visitTransitiveEndBorrows work with a BorrowedValue.

... and not only with a begin_borrow

Author: eeckstein

include/swift/SIL/OwnershipUtils.h

@@ -1076,10 +1076,10 @@ void findTransitiveReborrowBaseValuePairs(
     BorrowingOperand initialScopeOperand, SILValue origBaseValue,
     function_ref<void(SILPhiArgument *, SILValue)> visitReborrowBaseValuePair);
 
-/// Given a begin_borrow visit all end_borrow users of the borrow or its
-/// reborrows.
+/// Given a begin of a borrow scope, visit all end_borrow users of the borrow or
+/// its reborrows.
 void visitTransitiveEndBorrows(
-    BeginBorrowInst *borrowInst,
+    BorrowedValue beginBorrow,
     function_ref<void(EndBorrowInst *)> visitEndBorrow);
 
 } // namespace swift

lib/SIL/Utils/OwnershipUtils.cpp

@@ -1327,10 +1327,10 @@ void swift::findTransitiveReborrowBaseValuePairs(
 }
 
 void swift::visitTransitiveEndBorrows(
-    BeginBorrowInst *borrowInst,
+    BorrowedValue beginBorrow,
     function_ref<void(EndBorrowInst *)> visitEndBorrow) {
   SmallSetVector<SILValue, 4> worklist;
-  worklist.insert(borrowInst);
+  worklist.insert(beginBorrow.value);
 
   while (!worklist.empty()) {
     auto val = worklist.pop_back_val();

lib/SILOptimizer/Transforms/DeadCodeElimination.cpp

@@ -282,10 +282,10 @@ void DCE::markLive() {
             OwnershipKind::Owned) {
           markInstructionLive(borrowInst);
           // Visit all end_borrows and mark them live
-          auto visitEndBorrow = [&](EndBorrowInst *endBorrow) {
-            markInstructionLive(endBorrow);
-          };
-          visitTransitiveEndBorrows(borrowInst, visitEndBorrow);
+          visitTransitiveEndBorrows(BorrowedValue(borrowInst),
+            [&](EndBorrowInst *endBorrow) {
+              markInstructionLive(endBorrow);
+            });
           continue;
         }
         // If not populate reborrowDependencies for this borrow