Q2_0 group 64: CUDA backend

[khosravipasha]

DRAFT PR for testing and review

[Copilot]

Pull request overview

Adds CUDA backend support for GGML_TYPE_Q2_0 (group size 64) across the main CUDA execution paths (MMVQ mat-vec, MMQ mat-mat, row extraction, and dequantization/conversion), plus build/template plumbing to instantiate the needed kernels.

Changes:

• Implement Q2_0×Q8_1 CUDA dot product and wire it into the MMVQ (mul_mat_vec_q) dispatch path.
• Add MMQ (mul_mat_q) support for Q2_0 via new tile loader, type traits, and template instantiation generation.
• Enable Q2_0 for CUDA getrows + conversion/dequantization utilities, and mark relevant ops as supported by the CUDA backend.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ggml/src/ggml-cuda/vecdotq.cuh	Adds vec_dot_q2_0_q8_1 and VDR macros for Q2_0.
ggml/src/ggml-cuda/mmvq.cu	Routes Q2_0 through MMVQ vec-dot dispatch and type switch.
ggml/src/ggml-cuda/mmq.cuh	Adds Q2_0 MMQ tile loading and type trait wiring; updates q8_1 ds layout selection.
ggml/src/ggml-cuda/mmq.cu	Enables Q2_0 in MMQ type dispatch and MMQ usage heuristic.
ggml/src/ggml-cuda/template-instances/mmq-instance-q2_0.cu	New generated MMQ instantiation TU for Q2_0.
ggml/src/ggml-cuda/template-instances/generate_cu_files.py	Includes Q2_0 in the MMQ instantiation generation list.
ggml/src/ggml-cuda/ggml-cuda.cu	Marks Q2_0 as supported for relevant CUDA ops in capability checks.
ggml/src/ggml-cuda/getrows.cu	Adds Q2_0 case to CUDA get_rows dispatch using dequantize_q2_0.
ggml/src/ggml-cuda/dequantize.cuh	Introduces dequantize_q2_0 for CUDA dequantization kernels.
ggml/src/ggml-cuda/convert.cu	Enables Q2_0 conversions to fp16/fp32 (contiguous + non-contiguous) via new dequantizer.
ggml/src/ggml-cuda/common.cuh	Adds CUDA type traits (qk/qr/qi) for GGML_TYPE_Q2_0.
ggml/src/ggml-cpu/arch-fallback.h	Adds arch-fallback alias for ggml_vec_dot_q2_0_q8_0_generic on x86.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.