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Re: PATCH: Display "xchg %ax,%ax" and "xchg %rax,%rax"
- From: "Jan Beulich" <jbeulich at novell dot com>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: <binutils at sourceware dot org>
- Date: Fri, 09 Jun 2006 09:48:23 +0200
- Subject: Re: PATCH: Display "xchg %ax,%ax" and "xchg %rax,%rax"
- References: <20060609063838.GA10928@lucon.org>
>+ else if (prefixes == PREFIX_DATA)
>+ {
>+ /* We display "xchg %ax,%ax" instead of "data16 nop". */
>+ prefixes = 0;
>+ if (intel_syntax)
>+ strcpy (obuf, "xchg ax,ax");
>+ else
>+ strcpy (obuf, "xchg %ax,%ax");
>+ }
This is wrong in 16-bit mode. It might be better to call appropriate functions than to use hard-coded strings here.
+ else if (rex == 0x48)
+ {
+ /* We display "xchg %rax,%rax" instead of "rex64 nop". */
+ rex = 0;
+ if (intel_syntax)
+ strcpy (obuf, "xchg rax,rax");
+ else
+ strcpy (obuf, "xchg %rax,%rax");
+ }
This doesn't account for the rex bits that are ignored by this instruction. You should consume only rex.w here.
Jan