[NFC] Extracted isRedundantMoveValue.

Extracted the predicate from inline in RedundantMoveValueElimination
into the new function which can now be called from elsewhere
(CopyPropagation).

Author: nate-chandler

include/swift/SIL/OwnershipUtils.h

@@ -1347,6 +1347,14 @@ void visitTransitiveEndBorrows(
 /// - the value is itself a begin_borrow [lexical]
 bool isNestedLexicalBeginBorrow(BeginBorrowInst *bbi);
 
+/// Whether specified move_value is redundant.
+///
+/// A move_value is redundant if the lifetimes that it separates both have the
+/// same characteristics with respect to
+/// - lexicality
+/// - escaping
+bool isRedundantMoveValue(MoveValueInst *mvi);
+
 } // namespace swift
 
 #endif

lib/SIL/Utils/OwnershipUtils.cpp

@@ -2381,3 +2381,25 @@ bool swift::isNestedLexicalBeginBorrow(BeginBorrowInst *bbi) {
     return false;
   });
 }
+
+bool swift::isRedundantMoveValue(MoveValueInst *mvi) {
+  auto original = mvi->getOperand();
+
+  // If the moved-from value has none ownership, hasPointerEscape can't handle
+  // it, so it can't be used to determine whether escaping matches.
+  if (original->getOwnershipKind() != OwnershipKind::Owned) {
+    return false;
+  }
+
+  // First, check whether lexicality matches, the cheaper check.
+  if (mvi->isLexical() != original->isLexical()) {
+    return false;
+  }
+
+  // Then, check whether escaping matches, the more expensive check.
+  if (hasPointerEscape(mvi) != hasPointerEscape(original)) {
+    return false;
+  }
+
+  return true;
+}

lib/SILOptimizer/SemanticARC/RedundantMoveValueElimination.cpp

@@ -39,25 +39,10 @@ bool SemanticARCOptVisitor::visitMoveValueInst(MoveValueInst *mvi) {
   if (!ctx.shouldPerform(ARCTransformKind::RedundantMoveValueElim))
     return false;
 
-  auto original = mvi->getOperand();
-
-  // If the moved-from value has none ownership, hasPointerEscape can't handle
-  // it, so it can't be used to determine whether escaping matches.
-  if (original->getOwnershipKind() != OwnershipKind::Owned) {
-    return false;
-  }
-
-  // First, check whether lexicality matches, the cheaper check.
-  if (mvi->isLexical() != original->isLexical()) {
-    return false;
-  }
-
-  // Then, check whether escaping matches, the more expensive check.
-  if (hasPointerEscape(mvi) != hasPointerEscape(original)) {
+  if (!isRedundantMoveValue(mvi))
     return false;
-  }
 
   // Both characteristics match.
-  eraseAndRAUWSingleValueInstruction(mvi, original);
+  eraseAndRAUWSingleValueInstruction(mvi, mvi->getOperand());
   return true;
 }