use Value* constructor of CallSite to create potentially improper site, and test that

llvm-svn: 109581

llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

@@ -401,10 +401,9 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
       }
       
       continue;
-    } else if (CallSite::get(BBI).getInstruction() != 0) {
+    } else if (CallSite CS = cast<Value>(BBI)) {
       // If this call does not access memory, it can't
       // be undeadifying any of our pointers.
-      CallSite CS = CallSite::get(BBI);
       if (AA.doesNotAccessMemory(CS))
         continue;