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Re: [PATCH 5/6] x86/MPX: fix operand size handling


On Wed, Oct 9, 2013 at 12:36 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 08.10.13 at 17:45, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>> On Tue, Oct 8, 2013 at 7:43 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>> All MPX instructions in 64-bit mode ignore REX.W, which means we neither
>>> need to encode this bit nor should disassemble with 32-bit register
>>> operands.
>>>
>>> No MPX instructions would ever take a 16-bit register operand.
>>>
>>> gas/
>>> 2013-10-08  Jan Beulich <jbeulich@suse.com>
>>>
>>>         * tc-i386.c (process_suffix): Warn about 32-bit register operands
>>>         to MPX instructions in 64-bit mode.
>>
>> I think it should be an error.
>
> I can certainly change that - a warning just seemed a better match
> to hardware ignoring operand size here.

We can use separate entries with Reg32 for CpuNo64 and Reg64 for Cpu64,
similar to mov with debug registers.  Let's do that instead.

>>> opcodes/
>>> 2013-10-08  Jan Beulich <jbeulich@suse.com>
>>>
>>>         * i386-dis.c (intel_operand_size): Move v_bnd_mode alongside the
>>>         default case.
>>>         (OP_E_register): Move v_bnd_mode alongside m_mode.
>>>         * i386-opc.h (REGNAM_RAX): New.
>>>         * i386-opc.tbl (bndcl, bndcu, bndcn): Drop Reg16. Add NoRex64.
>>>         * i386-tbl.h: Re-generate.
>>>
>>
>> Should we also remove Disp16?
>
> Yes, we certainly could, but then also from the other MPX
> instructions. Logically this would belong into the address size fix
> patch though.
>
> Jan
>



-- 
H.J.


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