(Almost) always call reserveOperandSpace() on newly created PHINodes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128535 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 0087362..5e21a21 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1193,9 +1193,11 @@
     const StructType *ST =
       cast<StructType>(cast<PointerType>(PN->getType())->getElementType());
 
-    Result =
+    PHINode *NewPN =
      PHINode::Create(PointerType::getUnqual(ST->getElementType(FieldNo)),
                      PN->getName()+".f"+Twine(FieldNo), PN);
+    NewPN->reserveOperandSpace(PN->getNumIncomingValues());
+    Result = NewPN;
     PHIsToRewrite.push_back(std::make_pair(PN, FieldNo));
   } else {
     llvm_unreachable("Unknown usable value");