Adding description for utility functions in HPVMUtils.h for code generation

hpvm/include/SupportHPVM/HPVMUtils.h

@@ -7,6 +7,11 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
+//
+// This filed defines utility functions used for target-specific code generation 
+// for different nodes of dataflow graphs. 
+//
+//===----------------------------------------------------------------------===//
 
 #ifndef HPVM_UTILS_HEADER
 #define HPVM_UTILS_HEADER