Doxygenize the documentation comments

src/IceInst.cpp

 //===- subzero/src/IceInst.cpp - High-level instruction implementation ----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file implements the Inst class, primarily the various
-// subclass constructors and dump routines.
-//
+///
+/// \file
+/// This file implements the Inst class, primarily the various
+/// subclass constructors and dump routines.
+///
 //===----------------------------------------------------------------------===//
 
 #include "IceInst.h"
 
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceLiveness.h"
 #include "IceOperand.h"
 
 namespace Ice {
@@ skipping 911 matching lines @@
     // preserve these.
     return true;
   }
   if (!Dest->hasReg() && !SrcVar->hasReg() &&
       Dest->getStackOffset() == SrcVar->getStackOffset())
     return true;
   return false;
 }
 
 } // end of namespace Ice