[AArch64] PR target/20666, fix wrong encoding of new introduced BFC pseudo

[Jiong Wang]

On 07/11/16 11:55, Jan Beulich wrote:
>>>> On 10.10.16 at 18:40, <jiong.wang@foss.arm.com> wrote:
>> On 24/11/15 11:17, Matthew Wahab wrote:
>>> opcodes/
>>> 2015-11-24  Matthew Wahab  <matthew.wahab@arm.com>
>>>
>>>      * aarch64-asm-2.c: Regenerate.
>>>      * aarch64-asm.c (convert_bfc_to_bfm): New.
>> There looks like a copy & paste error in this function, and caused PR
>> target/20666.
>>
>> +convert_bfc_to_bfm (aarch64_inst *inst)
>> +{
>> +  int64_t lsb, width;
>> +
>> +  /* Insert XZR.  */
>> +  copy_operand_info (inst, 3, 2);
>> +  copy_operand_info (inst, 2, 1);
>> +  copy_operand_info (inst, 2, 0);
>>                               ^~~~~~~ should be "0".
> Why 0? That makes this particular copy_operand_info() invocation
> a no-op afaict. Aiui you mean 1 here instead.

Hi Jan,

   I mean 0 there.  as  "BFC Xd, lsb, width" is the simplified form of
"BFI Xd, XZR, lsb, width".

   Operands 1 is forced to XZR by the following code:
       inst->operands[1].reg.regno = 0x1f;

   But you are correct there, copy_operand_info (inst, 0, 0) then 
becomes no-op,
   we can delete that I think.

Regards,
Jiong