Add useful method, minor cleanups

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17715 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/CallSite.h

@@ -13,8 +13,7 @@
 // NOTE: This class is supposed to have "value semantics". So it should be
 // passed by value, not by reference; it should not be "new"ed or "delete"d. It
 // is efficiently copyable, assignable and constructable, with cost equivalent
-// to copying a pointer. (You will notice that it has only a single data
-// member.)
+// to copying a pointer (notice that it has only a single data member).
 //
 //===----------------------------------------------------------------------===//
 
@@ -85,6 +84,11 @@ public:
     I->setOperand(0, V);
   }
 
+  Value *getArgument(unsigned ArgNo) const {
+    assert(arg_begin() + ArgNo < arg_end() && "Argument # out of range!");
+    return *(arg_begin()+ArgNo);
+  }
+
   /// arg_iterator - The type of iterator to use when looping over actual
   /// arguments at this call site...
   typedef User::op_iterator arg_iterator;