De-duplicate common expression, NFC.

llvm-svn: 239736
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 45bb296..af42638 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -26,9 +26,9 @@
 
   // If requested, insert this instruction into a basic block...
   if (InsertBefore) {
-    assert(InsertBefore->getParent() &&
-           "Instruction to insert before is not in a basic block!");
-    InsertBefore->getParent()->getInstList().insert(InsertBefore, this);
+    BasicBlock *BB = InsertBefore->getParent();
+    assert(BB && "Instruction to insert before is not in a basic block!");
+    BB->getInstList().insert(InsertBefore, this);
   }
 }