Re: [PATCH] LoongArch: Add fcsr register names support

[WANG Xuerui <i.swmail@xen0n.name>]

Hi,

On 6/14/23 12:27, Feiyang Chen wrote:
> On Tue, Jun 13, 2023 at 5:49 PM WANG Xuerui <i.swmail@xen0n.name> wrote:
>>
>>
>> On 2023/6/12 16:36, Feiyang Chen wrote:
>> [snip]
>>> @@ -142,7 +144,19 @@ dis_one_arg (char esc1, char esc2, const char *bit_field,
>>>          info->fprintf_func (info->stream, "%s", loongarch_r_disname[u_imm]);
>>>          break;
>>>        case 'f':
>>> -      info->fprintf_func (info->stream, "%s", loongarch_f_disname[u_imm]);
>>> +      switch (esc2)
>>> +     {
>>> +     case 'c':
>>> +       if (u_imm < 4)
>>> +         info->fprintf_func (info->stream, "%s", loongarch_fc_disname[u_imm]);
>>> +       else
>>> +         /* For backward compatibility.  Display using general purpose
>>> +            register names if out of range.  */
>>> +         info->fprintf_func (info->stream, "%s", loongarch_r_normal_name[u_imm]);
>> I don't think it's proper to call *any* of the FCSRs "GPR" (or actually,
>> aliases to FCSR0, but that doesn't matter). What concrete scenario are
>> you trying to keep compatible with? A test case may explain it.
>>
> I agree with you, but the previous method of decoding treated "fcsr"
> as "gr." Therefore, to ensure proper compilation of the possible old
> code, I also need to consider "gr" as "fcsr." If you have a better
> solution, please inform me.
> For example, we may encounter the instruction "movgr2fcsr $r0, $r0,"
> and it is essential to parse it correctly. On another note, I am not
> experienced in creating test cases. Could you please assist me with
> that?
Sorry for the late reply. I meant not disallowing the old forms when 
assembling, but rather removing the workaround when disassembling -- I 
can't see a reason why FCSR0 ~ FCSR3 could be displayed as-is, but other 
unassigned but possible FCSR numbers still get displayed as GPRs; is it 
that you're following the ISA manual's exact wording that says there are 
only 4 FCSRs? In any case I find the special treatment a surprise and 
not very pleasant.