simplify

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109577 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/AliasSetTracker.cpp b/lib/Analysis/AliasSetTracker.cpp
index b14043e..8581f59 100644
--- a/lib/Analysis/AliasSetTracker.cpp
+++ b/lib/Analysis/AliasSetTracker.cpp
@@ -456,8 +456,7 @@
 
   // If this is a call instruction, remove the callsite from the appropriate
   // AliasSet.
-  CallSite CS = CallSite::get(PtrVal);
-  if (CS.getInstruction())
+  if (CallSite CS = PtrVal)
     if (!AA.doesNotAccessMemory(CS))
       if (AliasSet *AS = findAliasSetForCallSite(CS))
         AS->removeCallSite(CS);