feat: support MCCL on Moore Threads

[Ren-HL]

Summary

Add MCCL backend support for Moore Threads by reusing the shared MCCL CCL abstraction introduced in the current codebase. This PR adds the Moore MCCL provider alias, marks BackendType::kMccl with Device::Type::kMoore as a supported backend/device combination, and updates CMake so MCCL can be discovered and required for either MetaX or Moore Threads builds.

This keeps the platform/backend separation intact: Moore Threads does not duplicate MCCL operation implementations, and it can use the existing src/backends/ccl/mccl implementation through a small provider-specific api.h. It also completes the Moore runtime interface required by communicator initialization and reports BFloat16 as unsupported when it is not exposed by the Moore MCCL headers.

Changes

• Moore MCCL Provider

  • Add src/backends/ccl/mccl/moore/api.h.
  • Bind CclApi<BackendType::kMccl, Device::Type::kMoore> to McclApi<Device::Type::kMoore>.

• Backend/device support

  • Update src/backend_device_map.h so BackendType::kMccl is accepted with Device::Type::kMoore.
  • Add the missing musaGetDevice binding required by communicator initialization.

• CMake detection and linking

  • Allow MCCL auto-detection when WITH_MOORE is enabled.
  • Add MUSA-style MCCL search hints from MUSA_ROOT, MUSA_HOME, MUSA_PATH, and /usr/local/musa.
  • Update the explicit WITH_MCCL requirement so MCCL accepts MetaX or Moore Threads GPU support.
  • Propagate the Moore MCCL type capability definition to internal example targets.

• MCCL type support

  • Report BFloat16 as unsupported for Moore MCCL because the tested MCCL headers do not expose mcclBfloat16.
  • Preserve the existing MetaX MCCL BFloat16 behavior.

• Documentation

  • Update README.md to document MCCL availability on Moore Threads.

Platform and Backend Affected

Platform

• CPU
• NVIDIA GPU
• Iluvatar GPU
• MetaX GPU
• Moore Threads GPU
• Cambricon MLU

Backend

• OpenMPI
• MPICH
• NCCL
• MCCL

Performance Impact

• No performance impact
• Performance improved
• Performance regression possible

N/A.

Known Issues & Future Work

• The tested MUSA 4.3.1 and MCCL 2.11.4 headers do not expose mcclBfloat16, so BFloat16 operations are reported as unsupported for Moore MCCL. If a future Moore MCCL version exposes native BFloat16 support, the provider capability can be updated accordingly.

Test Results

Test Involved Platform

• CPU
• NVIDIA GPU
• Iluvatar GPU
• MetaX GPU
• Moore Threads GPU
• Cambricon MLU

Test Involved Backend

• OpenMPI
• MPICH
• NCCL
• MCCL

Moore Threads with MCCL:

Test environment:

• 8 × MTT S5000
• MUSA 4.3.1
• MCCL 2.11.4

Validation results:

• 1-GPU Float32 AllReduce: expected 1, actual 1.
• 2-GPU Float32 AllReduce: expected 3, actual 3.
• 8-GPU Float32 AllReduce: expected 36, actual 36.
• Moore and MCCL automatic detection passed.
• The library and all internal examples built successfully.

ccl_all_reduce.log

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Testing

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