[RFA] Add comment to opcode/i386.h

[Doug Evans]

Hi.  A simple comment addition to opcode/i386.h.
Ok to check in?

2009-02-01  Doug Evans  <dje@google.com>

	* i386.h: Add comment regarding sse* insns and prefixes.

Index: opcode/i386.h
===================================================================
RCS file: /cvs/src/src/include/opcode/i386.h,v
retrieving revision 1.80
diff -u -p -u -r1.80 i386.h
--- opcode/i386.h	29 Jan 2009 00:29:53 -0000	1.80
+++ opcode/i386.h	1 Feb 2009 20:54:23 -0000
@@ -59,6 +59,11 @@
 /* The opcode for the fwait instruction, which disassembler treats as a
    prefix when it can.  */
 #define FWAIT_OPCODE 0x9b
+
+/* Instruction prefixes.
+   NOTE: For certain SSE* instructions, 0x66,0xf2,0xf3 are treated as
+   part of the opcode.  Other prefixes may still appear between them
+   and the 0x0f part of the opcode.  */
 #define ADDR_PREFIX_OPCODE 0x67
 #define DATA_PREFIX_OPCODE 0x66
 #define LOCK_PREFIX_OPCODE 0xf0