add python level meta registration method

Signed-off-by: ganyi <pleaplusone.gy@gmail.com>

Author: ganyi1996ppo

vllm_ascend/ops/meta_registration.py

@@ -0,0 +1,50 @@
+import torch
+from torch.library import Library
+
+lib = Library("_C", "IMPL")
+
+def register_meta_if_necessary(ns:str, op_name: str, fn, overload: str = ""):
+  if overload != "":
+    op_name = op_name + "." + overload
+  schema_to_find = ns + "::" + op_name
+  meta_impl_list = torch._C._dispatch_get_registrations_for_dispatch_key("Meta")
+  if schema_to_find in meta_impl_list:
+    return 
+  lib.impl(op_name, fn, "Meta")
+
+def rotary_embedding_meta(
+    positions: torch.Tensor,
+    query: torch.Tensor,
+    key: torch.Tensor,
+    head_size: int,
+    cos_sin_cache: torch.Tensor,
+    is_neox: bool):
+
+  num_tokens = positions.numel()
+  query_hidden_size = query.numel() / num_tokens
+  key_hidden_size = key.numel() / num_tokens
+  num_heads = query_hidden_size / head_size
+  num_kv_heads = key_hidden_size / head_size
+
+  query_dst = torch.empty_like(query).view(num_tokens, num_heads, head_size)
+  key_dst = torch.empty_like(key).view(num_tokens, num_kv_heads, head_size)
+  return query_dst, key_dst
+
+
+def get_masked_input_and_mask_meta(
+    input: torch.Tensor,
+    org_vocab_start_index: int,
+    org_vocab_end_index: int,
+    num_org_vocab_padding: int,
+    added_vocab_start_index: int,
+    added_vocab_end_index: int):
+
+  masked_input = torch.empty_like(input)
+  mask = torch.empty_like(input).to(torch.bool)
+
+  return masked_input, mask
+
+
+
+register_meta_if_necessary("_C", "rotary_embedding", rotary_embedding_meta)
+register_meta_if_necessary("_C", "get_masked_input_and_mask", get_masked_input_and_mask_meta)

vllm_ascend/utils.py

@@ -216,6 +216,8 @@ def enable_custom_op():
     try:
         # register custom ops into torch_library here
         import vllm_ascend.vllm_ascend_C  # type: ignore  # noqa: F401
+        # register the meta implementation for custom kernel if necessary
+        import vllm_ascend.ops.meta_registration  # type: ignore  # noqa: F401
         _CUSTOM_OP_ENABLED = True
     except ImportError:
         _CUSTOM_OP_ENABLED = False