8230015: [instruction selector] generic vector operands support.

[Leslie Zhai]

Hi Jatin,

Thanks again for your great work!

Before vs After ported

16137992 vs 15803384

Cheers,

Leslie Zhai


在 2021年04月15日 14:48, Bhateja, Jatin 写道:
> Hi Vladimir,
> Thanks for responding on my behalf.
>
> Best Regards,
> Jatin
>
>> -----Original Message-----
>> From: Vladimir Ivanov <vladimir.x.ivanov at oracle.com>
>> Sent: Wednesday, April 14, 2021 10:41 PM
>> To: Leslie Zhai <zhaixiang at loongson.cn>
>> Cc: Bhateja, Jatin <jatin.bhateja at intel.com>; hotspot-compiler-
>> dev at openjdk.java.net
>> Subject: Re: 8230015: [instruction selector] generic vector operands
>> support.
>>
>> Hi Leslie,
>>
>> I'm not sure what you are trying to achieve with the port.
>>
>> Currently, there are 3 platform-specific methods which
>> Matcher::do_postselect_cleanup() relies on:
>>
>>     Matcher::pd_specialize_generic_vector_operand()
>>     Matcher::is_generic_reg2reg_move()
>>     Matcher::is_generic_vector()
>>
>> It should be enough to provide implementations for those methods on
>> YOURARCH to make Matcher::do_postselect_cleanup() working.
>>
>> Can you elaborate on what exactly you are trying to accomplish?
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> On 14.04.2021 08:09, Leslie Zhai wrote:
>>> Hi Jatin,
>>>
>>> Thanks for your great work!
>>>
>>> libjvm.so reduced +1MB will help SPECjvm2008 some benchmark +44% speed
>> up.
>>> Then I tried to port 8234391: C2: Generic vector operands for
>>> `YOURARCH` about LoadVector and StoreVector at first.
>>>
>>> Only `Matcher::regmask_for_ideal_register` was able to call
>>> `Matcher::is_generic_vector`, but compared with X86,
>>> `Matcher::do_postselect_cleanup` was also able to call
>>> `Matcher::is_generic_vector` too.
>>>
>>> I debug the `Matcher::do_postselect_cleanup`:
>>>
>>> diff --git a/src/hotspot/share/opto/matcher.cpp
>>> b/src/hotspot/share/opto/matcher.cpp
>>> index 0846cad3c3f..8fd644d2d93 100644
>>> --- a/src/hotspot/share/opto/matcher.cpp
>>> +++ b/src/hotspot/share/opto/matcher.cpp
>>> @@ -309,6 +309,9 @@ void Matcher::match( ) {
>>>       C->record_method_not_compilable("must be able to represent all
>>> call arguments in reg mask");
>>>     }
>>>
>>> +#ifdef YOURARCH64
>>> +  do_postselect_cleanup();
>>> +#endif
>>>     if (C->failing())  return;  // bailed out on incoming arg failure
>>>
>>>     // ---------------
>>> @@ -2630,8 +2633,10 @@ void
>>> Matcher::specialize_generic_vector_operands() {
>>>           int opnd_idx = m->operand_index(1);
>>>           Node* def = m->in(opnd_idx);
>>>           m->subsume_by(def, C);
>>> +#if !defined(YOURARCH64)
>>>         } else if (m->is_MachTemp()) {
>>>           // process MachTemp nodes at use site (see
>>> Matcher::specialize_vector_operand)
>>> +#endif
>>>         } else {
>>>           specialize_mach_node(m);
>>>         }
>>>
>>> But `Matcher::do_postselect_cleanup` was still not able to be called.
>>>
>>>> Current patch enables this support only for x86 target, to get a
>>> feedback from community.
>>>
>>> Then how to port Generic vector operands for other targets?
>>>
>>> Thanks,
>>>
>>> Leslie Zhai
>>>
>>>
>>> 在 2019年08月22日 14:49, Bhateja, Jatin 写道:
>>>> Hi All,
>>>>
>>>> Please find below a patch for generic vector operands[1] support
>>>> during instruction selection.
>>>>
>>>> Motivation behind the patch is to reduce the number of vector
>>>> selection patterns whose operands meagerly differ in vector lengths.
>>>> This will not only result in lesser code being generated by ADLC
>>>> which effectively translates to size reduction in libjvm.so but also
>>>> help in better maintenance of AD files.
>>>>
>>>> Using generic operands we were able to collapse multiple vector
>>>> patterns over mainline
>>>>                Initial number of vector instruction patterns
>>>> (vec[XYZSD] + legVec[ZXYSD]   :  510
>>>>                Reduced vector instruction patterns  (vecG +
>>>> legVecG)                                  :  222
>>>>
>>>> With this we could see around 1MB size reduction in libjvm.so.
>>>>
>>>> In order to have minimal impact over downstream compiler passes, a
>>>> post-selection pass has been introduced (currently enabled only for
>>>> X86 target)
>>>> which replaces these generic operands with their corresponding
>>>> concreter vector length variants.
>>>>
>>>> JBS      : https://bugs.openjdk.java.net/browse/JDK-8230015
>>>> Patch  :
>>>> http://cr.openjdk.java.net/~jbhateja/genericVectorOperands/webrev.00/
>>>>
>>>> Kindly review and share your feedback.
>>>>
>>>> Best Regards,
>>>> Jatin Bhateja
>>>>
>>>> [1]
>>>> http://cr.openjdk.java.net/~jbhateja/genericVectorOperands/generic_op
>>>> erands_support_v1.0.pdf
>>>>
>>>>