Adding description for code generation pass for CPU in DFG2LLVM_CPU.cpp

hpvm/lib/Transforms/DFG2LLVM_CPU/DFG2LLVM_CPU.cpp

@@ -6,6 +6,11 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
+//
+// This pass is responsible for generating code for host code and kernel code 
+// for CPU target using HPVM dataflow graph.
+//
+//===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "DFG2LLVM_CPU"
 #include "SupportHPVM/DFG2LLVM.h"