[Local] Promote an utility that could be used elsewhere. NFCI.

llvm-svn: 348804
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 61b6d7c..cb893ea 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -789,13 +789,7 @@
       // Discard any debug info related to the expressions that has changed (we
       // can leave debug infor related to the root, since the result of the
       // expression tree should be the same even after reassociation).
-      SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
-      findDbgUsers(DbgUsers, ExpressionChanged);
-      for (auto *DII : DbgUsers) {
-        Value *Undef = UndefValue::get(ExpressionChanged->getType());
-        DII->setOperand(0, MetadataAsValue::get(DII->getContext(),
-                                                ValueAsMetadata::get(Undef)));
-      }
+      replaceDbgUsesWithUndef(ExpressionChanged);
 
       ExpressionChanged->moveBefore(I);
       ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->user_begin());
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index d9e0c15..2b7d7ad 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -476,6 +476,17 @@
   }
 }
 
+bool llvm::replaceDbgUsesWithUndef(Instruction *I) {
+  SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
+  findDbgUsers(DbgUsers, I);
+  for (auto *DII : DbgUsers) {
+    Value *Undef = UndefValue::get(I->getType());
+    DII->setOperand(0, MetadataAsValue::get(DII->getContext(),
+                                            ValueAsMetadata::get(Undef)));
+  }
+  return !DbgUsers.empty();
+}
+
 /// areAllUsesEqual - Check whether the uses of a value are all the same.
 /// This is similar to Instruction::hasOneUse() except this will also return
 /// true when there are no uses or multiple uses that all refer to the same