Home Original page

[PATCH] x86: Mark cvtpi2ps and cvtpi2pd as MMX

Jan Beulich jbeulich@suse.com
Wed Feb 19 14:58:00 GMT 2020 
On 19.02.2020 15:46, H.J. Lu wrote:
> On Wed, Feb 19, 2020 at 6:36 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 19.02.2020 15:23, H.J. Lu wrote:
>>> On Wed, Feb 19, 2020 at 6:19 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>> On 19.02.2020 15:09, H.J. Lu wrote:
>>>>> On Wed, Feb 19, 2020 at 5:53 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>>>> As per your suggested doc patch "pure SSE" means "not touching MMX
>>>>>> registers or state". This is the case for CVTPI2PD.
>>>>>
>>>>> I will exclude cvtpi2ps and cvtpi2pd explicitly.
>>>>
>>>> Okay, this would clarify what "pure SSE" means. My next objection
>>>> then is to make a connection between "pure SSE" and the feature
>>>> used property. There, as made pretty clear by my earlier inquiry
>>>> about the intentions of this feature tracking, things should be
>>>> really tied to hardware behavior. I.e. "not touching MMX registers
>>>> or state" ==> MMX feature not recorded as being used. No
>>>> exceptions for any insns.
>>>
>>> Intention is to treat cvtpi2ps and cvtpi2pd as MMX.
>>
>> Well, I understand you want to special case these. But the model
>> behind the feature recording shouldn't require any (such) special
>> cases. To possible consumers of this information it doesn't matter
>> what exact insns are being used. Instead, affected machine state
>> is what counts. Hence the individual flags should be tied to the
>> machine state individual insns consume or touch, and at that point
>> no special cases like the ones you suggest are going to be needed
>> (special casing may still be needed when possibly the
>> consumed/touched machine state can't be inferred from other
>> information available, most notably the insn template and its
>> actual operands).
> 
> Intention is to mark any instructions whose form include MMX register
> or state as MMX.

Exactly. And hence CVTPI2PD should not get such marking when
having a memory operand.

Jan
More information about the Binutils mailing list