RFR: 8358521: Optimize vector operations by reassociating broadcasted inputs [v2]

[Xiaohong Gong]

On Tue, 10 Feb 2026 05:34:06 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Hi all,
>> 
>> This patch optimizes SIMD kernels making heavy use of broadcasted inputs through following reassociating ideal transformations.
>> 
>> 
>>  VectorOperation (VectorBroadcast INP1,  VectorBroadcast INP2) => 
>>                             VectorBroadcast (ScalarOpration INP1, INP2)
>> 
>>  VectorOperation (VectorBroadcast INP1) (VectorOperation (VectorBroadcast INP2) INP3) => 
>>                              VectorOperation INP3 (VectorOperation (VectorBroadcast INP1) (VectorOperation INP2))
>> 
>> 
>> The idea is to push broadcasts across the vector operation and replace the vector with an equivalent, cheaper scalar variant.  Currently, patch handles most common vector operations.
>> 
>> Following are the performance number of benchmark included with this patch on latest generation x86 targets:- 
>> 
>> **AMD Turin (2.1GHz)**
>> <img width="1122" height="355" alt="image" src="https://github.com/user-attachments/assets/3f5087bf-0e14-4c56-b0c2-3d23253bad54" />
>> 
>> **Intel Granite Rapids (2.1GHz)**
>> <img width="1105" height="325" alt="image" src="https://github.com/user-attachments/assets/c8481f86-4db2-4c4e-bd65-51542c59fe63" />
>> 
>> 
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review comments resolutions

src/hotspot/share/opto/vectornode.cpp line 1303:

> 1301: //
> 1302: Node* VectorNode::reassociate_vector_operation(PhaseGVN* phase) {
> 1303:   if (is_commutative_vector_operation(Opcode()) && is_integral_type(vect_type()->element_basic_type())) {

Suggestions

  // Only integral vector operations support reassociate ...
  if (is_integral_type(vect_type()->element_basic_type())) {
    return nullptr;
  }

  // Only commutative vector operations supports ...
  if (!is_commutative_vector_operation(Opcode()) {
    return nullptr;
  }

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25617#discussion_r2796430943