cache result of operator*

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107972 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index eb22b84..af2958f 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -715,9 +715,10 @@
 static bool IsOnlyNullComparedAndFreed(const Value &V) {
   for (Value::const_use_iterator UI = V.use_begin(), UE = V.use_end();
        UI != UE; ++UI) {
-    if (isFreeCall(*UI))
+    const User *U = *UI;
+    if (isFreeCall(U))
       continue;
-    if (const ICmpInst *ICI = dyn_cast<ICmpInst>(*UI))
+    if (const ICmpInst *ICI = dyn_cast<ICmpInst>(U))
       if (ICI->isEquality() && isa<ConstantPointerNull>(ICI->getOperand(1)))
         continue;
     return false;