[#8732][feat] Add ReLU2 to TRTLLM Cutlass MoE BF16 kernels

[galagam]

Summary by CodeRabbit

• New Features
  • Enabled Relu2 activation support in MoE GEMM kernel operations, expanding the available activation functions for mixture-of-experts tensor computations.

Description

Cutlass MoE kernels were integrated in #9011, and FP8 support is already integrated. This PR adds boilerplate code to enable BF16 invocation as well.

Test Coverage

PR Checklist

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[coderabbitai]

📝 Walkthrough

Walkthrough

Adds Relu2 activation support to CUTLASS-based operations by introducing a new epilogue operation tag and enabling its dispatch in MoE GEMM kernels, converting previous unsupported error handling to a functional code path.

Changes

Cohort / File(s)	Summary
Epilogue infrastructure cpp/tensorrt_llm/cutlass_extensions/include/cutlass_extensions/epilogue_helpers.h	Added EpilogueOpDefaultRelu2 struct tag and introduced corresponding Epilogue template specialization using LinearCombinationGeneric with Relu2 activation, default scale mode, and nearest rounding enabled.
MoE GEMM kernel dispatch cpp/tensorrt_llm/kernels/cutlass_kernels/moe_gemm/moe_gemm_template_dispatch.h	Changed ActivationType::Relu2 handling in MoeGemmRunner::moeGemmBiasAct from throwing an unsupported error to dispatching with the new EpilogueOpDefaultRelu2 epilogue operation.

Sequence Diagram

sequenceDiagram
    participant Caller as MoE GEMM Caller
    participant Dispatch as moeGemmBiasAct Dispatch
    participant Epilogue as EpilogueOpDefaultRelu2

    rect rgb(200, 240, 200)
    Note over Caller,Epilogue: Before: Relu2 ActivationType
    Caller->>Dispatch: moeGemmBiasAct(..., ActivationType::Relu2, ...)
    Dispatch->>Dispatch: Check ActivationType::Relu2
    Dispatch-->>Caller: Throw unsupported error ✗
    end

    rect rgb(200, 220, 240)
    Note over Caller,Epilogue: After: Relu2 ActivationType
    Caller->>Dispatch: moeGemmBiasAct(..., ActivationType::Relu2, ...)
    Dispatch->>Dispatch: Check ActivationType::Relu2
    Dispatch->>Epilogue: Dispatch with EpilogueOpDefaultRelu2
    Epilogue->>Epilogue: Apply LinearCombinationGeneric<Relu2>
    Epilogue-->>Caller: Return result ✓
    end

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

• Straightforward additions following existing patterns (new epilogue tag and template specialization)
• Minimal behavioral impact: converts error path to functional path with single-operation dispatch
• Limited file scope with cohesive changes related to Relu2 activation support

Pre-merge checks and finishing touches

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.
Description check	❓ Inconclusive	PR description is mostly complete with context explaining the purpose (BF16 support for Cutlass MoE kernels), but is missing specific information in Test Coverage section.	Provide specific test cases or test plan that verify BF16 invocation works correctly for Cutlass MoE kernels to demonstrate sufficient test coverage.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding ReLU2 activation support to TensorRT-LLM Cutlass MoE BF16 kernels.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[galagam]

/bot run

[tensorrt-cicd]

PR_Github #24673 [ run ] triggered by Bot. Commit: 22dd0ba

[tensorrt-cicd]

PR_Github #24673 [ run ] completed with state SUCCESS. Commit: 22dd0ba
/LLM/main/L0_MergeRequest_PR pipeline #18629 completed with status: 'FAILURE'

[galagam]

/bot run

[tensorrt-cicd]

PR_Github #24774 [ run ] triggered by Bot. Commit: 493686f

[nvchenghaoz]

will this PR fix the #9184?

[tensorrt-cicd]

PR_Github #24774 [ run ] completed with state SUCCESS. Commit: 493686f
/LLM/main/L0_MergeRequest_PR pipeline #18691 completed with status: 'SUCCESS'
Pipeline passed with automatic retried tests. Check the rerun report for details.