[PATCH] [RS6000] Change maddld match_operand from DI to GPR

Kewen.Lin linkw@linux.ibm.com
Mon Jun 24 07:49:00 GMT 2019


on 2019/6/24 下午3:43, Kewen.Lin wrote:
> on 2019/6/24 下午3:19, Segher Boessenkool wrote:
>> On Mon, Jun 24, 2019 at 02:45:09PM +0800, Kewen.Lin wrote:
>>> on 2019/6/24 下午2:00, Li Jia He wrote:
>>>> -#define TARGET_MADDLD	(TARGET_MODULO && TARGET_POWERPC64)
>>>> +#define TARGET_MADDLD	TARGET_MODULO
>>>
>>> IMHO, I don't think this removal of TARGET_POWERPC64 is reasonable.
>>> As ISA V3.0, the description of this insn maddld is:
>>> GPR[RT].dword[0] ← Chop(result, 64)
>>>
>>> It assumes the GPR has dword, it's a 64-bit specific insn, right?
>>> Your change relaxes it to be adopted on 32-bit.
>>> Although it's fine for powerpc LE since it's always 64-bit, it will
>>> have problems for power9 32bit like AIX?
>>
>> Hi Kewen,
>>
>> Newer ISAs require 64-bit to be implemented.  There are no optional
>> 64-bit categories anymore.  Since this instruction is enabled for P9
>> (ISA 3.0) only (that's the TARGET_MODULO), it's fine.
>>
>> What you are saying is quite true for older CPUs/ISAs though: there you
>> have to make sure you are targetting a CPU that supports the 64-bit
>> categories, before using any 64-bit insns.
>>
>> But those days are gone :-)
>>
> 
> Hi Segher,
> 
> Good to know that, thanks a lot for the information!  It's fine then.
> 
> It sounds like we can have a clean up for some others like 
> TARGET_EXTSWSLI. :)
> 

Sorry, maybe not, it's not similar to maddld for 32bit operations.


Thanks,
Kewen

> 
> Thanks,
> Kewen
> 
>>
>> Segher
>>
> 



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