Add namespace comments for doxygen

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6581 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86.h

@@ -41,9 +41,9 @@ Pass *createX86CodePrinterPass(std::ostream &O);
 ///
 Pass *createEmitX86CodeToMemory();
 
-// Put symbolic names in a namespace to avoid causing these to clash with all
-// kinds of other things...
-//
+/// X86 namespace - This namespace contains all of the register and opcode enums
+/// used by the X86 backend.
+///
 namespace X86 {
   // Defines a large number of symbolic names for X86 registers.  This defines a
   // mapping from register name to register number.

lib/Target/X86/X86CodeEmitter.cpp

@@ -264,8 +264,9 @@ void Emitter::emitGlobalAddressForPtr(GlobalValue *GV) {
 
 
 
-
-namespace N86 {  // Native X86 Register numbers...
+/// N86 namespace - Native X86 Register numbers... used by X86 backend.
+///
+namespace N86 {
   enum {
     EAX = 0, ECX = 1, EDX = 2, EBX = 3, ESP = 4, EBP = 5, ESI = 6, EDI = 7
   };