cuda.core: support "3D copies with attributes" (follow-on to issue #2365) #2660

Summary

#2365 tracked two CUDA 13.2 attribute-carrying copy entry points together. #2636 implemented the flat 1D case (cuMemcpyWithAttributesAsync, exposed via Buffer.copy_to/Buffer.copy_from's new options keyword). This issue splits off the remaining, unimplemented half:

• cuMemcpy3DWithAttributesAsync(CUDA_MEMCPY3D_BATCH_OP* op, unsigned long long flags, CUstream) — executes a single 3D copy operation described by a CUDA_MEMCPY3D_BATCH_OP, reusing the CUmemcpySrcAccessOrder/CUmemcpyFlags machinery already introduced for cuMemcpyBatchAsync (12.8) and consumed by #2636's CopyOptions.

cuda.core has no API for 3D/strided copies with attributes today.

Underlying C API

cuMemcpy3DWithAttributesAsync (CUDA 13.2). Takes a single CUDA_MEMCPY3D_BATCH_OP:

• src, dst: CUmemcpy3DOperand, each either a raw pointer operand (base pointer + row/depth pitch, matching a strided/3D buffer layout) or a CUDA array operand (CUarray/CUmipmappedArray + subresource).
• extent: CUextent3D (width/height/depth), all three components must be nonzero.
• srcAccessOrder: CUmemcpySrcAccessOrder — the same three-way hint (STREAM/DURING_API_CALL/ANY) as the 1D and batched entry points.
• flags: CUmemcpyFlags (e.g. CU_MEMCPY_FLAG_PREFER_OVERLAP_WITH_COMPUTE), same as the other attribute-carrying copies.

Relation to #2636

Should reuse as much of #2636's plumbing as possible rather than duplicating it:

• MemcpySrcAccessOrder / MemcpyOverlapMode (cuda.core._memory._copy_enums) — same enums, no new ones needed for those two fields.
• The DURING_API_CALL fallback hazard and its guard, _reject_unsupported_during_api_call — the pointer-operand fallback (if any) would have the same correctness hazard as the 1D/batched paths and needs the same treatment, not a silently-downgraded copy.
• The _with_attributes_available()-style CUDA 13.2 version gate, and the graph-capture / LEGACY_DEFAULT_STREAM rejection pattern established there.

Design sketch (draft — needs design-meeting review)

cuda.core already has StridedMemoryView with copy_to/copy_from, and separately texture.Array/texture.MipmappedArray for CUDA-array-backed storage. The pointer-operand case maps naturally onto a strided/3D buffer view; the array-operand case maps onto the existing texture array types. Open questions for the meeting:

1. Does this become StridedMemoryView.copy_to/copy_from gaining an options keyword (pointer operands), a new API for the array-operand case, or both under one entry point?
2. How do row/depth pitch and extent get derived: from StridedMemoryView's shape/strides directly, or does the caller supply them explicitly?
3. Should mixed operand kinds be supported in one call (e.g. array → pointer), or should the initial version only cover the common pointer-to-pointer case?
4. Version gating (CUDA 13.2+) and error behavior, matching the pattern established in cuda.core: introduce copy options for Buffer.copy_{to/from} #2636.
5. Separate PR from any future cuMemcpy3DBatchAsync (multiple 3D ops per call) work, if that ever gets tracked.

References

• Driver docs: https://docs.nvidia.com/cuda/cuda-driver-api/
• Parent issue: [FEA] cuda.core: support copies with attributes (CUDA 13.2) #2365
• Implements the 1D half: cuda.core: introduce copy options for Buffer.copy_{to/from} #2636