[PATCH] Clean reg class and base_reg for input output operand (%dx).

[Jan Beulich]

On 12.12.2023 08:51, Cui, Lili wrote:
>>>>> --- a/gas/config/tc-i386.c
>>>>> +++ b/gas/config/tc-i386.c
>>>>> @@ -13016,6 +13016,8 @@ i386_att_operand (char *operand_string)
>>>>>  	  && !operand_type_check (i.types[this_operand], disp))
>>>>>  	{
>>>>>  	  i.types[this_operand] = i.base_reg->reg_type;
>>>>> +	  i.types[this_operand].bitfield.class = 0;
>>>>> +	  i.base_reg = NULL;
>>>>
>>>> I agree with the latter, but I don't understand the former. The more
>>>> that in earlier discussion on the APX subthread I clearly indicated
>>>> what I think needs doing here.
>>>>
>>>
>>> The original issue was that we encountered a segment fault when accessing
>> i.op[op].regs->reg_flags, and since the input was (%dx), we treat it as
>> memory, so I think we need to clean up i.types[this_operand]. bitfield.class =
>> 0 and leave i.base_reg there, it means i.base_reg does not need to be
>> cleaned.
>>
>> As said before - what is missing as far as I understand it is the updating of
>> i.op[].regs in the code above. That ought to be (much) preferred over
>> invalidating .class (and thus perhaps causing new latent issues).
>>
> 
> Changed.  Can I check in this patch ?

If the change is enough to avoid any respective oddities in the APX
patches, then yes, please go ahead.

Jan

>     Clean base_reg and assign correct values to regs for input_output_operand (%dx).
> 
>     For special processing of input and output operands (%dx),
>     the state of some variables needs to be cleaned.
> 
>     gas/ChangeLog:
> 
>             * config/tc-i386.c (i386_att_operand): Assign values to regs and
>             clean i.base_reg for input output operand (%dx).
> 
> diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
> index 4f3864f2ba7..3f1b39baddc 100644
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -13016,6 +13016,8 @@ i386_att_operand (char *operand_string)
>           && !operand_type_check (i.types[this_operand], disp))
>         {
>           i.types[this_operand] = i.base_reg->reg_type;
> +         i.op[this_operand].regs = i.base_reg;
> +         i.base_reg = NULL;
>           i.input_output_operand = true;
>           return 1;
>         }
> 
> Thanks,
> Lili.