openvino: merge refactor PR - isolate op support, manage buffers, document API

[Copilot]

Ports and rebases PR #278 (zhaixuejun1993/llama.cpp:xuejun/refactor-ggml-openvino) onto the latest dev_backend_openvino, resolving all merge conflicts.

Overview

Structural refactor of the OpenVINO backend, splitting a monolithic ggml-openvino.cpp into focused modules, plus conflict resolution to incorporate fixes that landed on dev_backend_openvino after the PR diverged.

Changes

• New modules extracted from ggml-openvino.cpp:

  • ggml-openvino-op-support.cpp/h - op support policy (ggml_openvino_device_supports_op_impl), previously inline; includes full per-op policy table in header comments
  • ggml-openvino-buffer.cpp/h - buffer allocation and tensor extra management
  • ggml-openvino-weight-buffer-release.cpp/h - GGML_OPENVINO_RELEASE_WEIGHTS RSS reclaim logic

• ggml-openvino.cpp: now a thin orchestration layer; device_supports_op delegates to ggml_openvino_device_supports_op_impl; buffer_type_context gains bool is_host field

• Conflict resolutions:

  • ggml-openvino-op-support.cpp (GGML_OP_CPY): added quantized-destination guard from ae02f5e after the existing BF16 src/dst check:

    // CPY to a quantized destination (e.g. f32 -> q4_0) is numerically unstable with OpenVINO backend.
    if (ggml_is_quantized(op->type)) {
        return true;
    }

  • utils.cpp (is_model_splitted): retained GGML_OPENVINO_ENABLE_FALLBACK env-var gate from c66a9c9
  • openvino/op/sqr.cpp: trailing newline preserved (matches base)
  • tests/test-llama-archs.cpp: auto-merged correctly; has_openvino skip removed, Meta tensor-split config always appended; new arch entries (QWEN3TTS, MUSE_GLIMMER, GRANITE_SWITCH) and updated WebGPU/HIP skip logic retained from base

Additional information

Merge commit on branch copilot/xuejunrefactor-ggml-openvino (rebased onto ravi9/llama.cpp:dev_backend_openvino at 37b164f).

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure: YES - AI agent performed the merge, conflict resolution, and authored this description. The contributor is responsible for reviewing all changes before submission.