8230015: [instruction selector] generic vector operands support.

[Vladimir Ivanov]

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_operands_support_v1.0.pdf 
>>
>>
>