[Feat] Flash comm allgher ep (#3334)

Support flash comm v1(Sequence Parallelism) for Allgather EP.

- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

---------

Signed-off-by: realliujiaxu <realliujiaxu@163.com>
Co-authored-by: zhaozx-cn <zhaozx2116@163.com>

vllm_ascend/utils.py

@@ -55,6 +55,7 @@ _PREFETCH_STREAM = None
 _ASCEND_CUSTOMOP_IS_REIGISTERED = False
 _DEFAULT_BUFFER_SIZE = 200
 _MIN_DP_BUFFER_SIZE = 50
+_IS_MOE_MODEL = None
 
 
 def is_310p():
@@ -609,12 +610,24 @@ def enable_sp(vllm_config=None) -> bool:
         vllm_config = get_current_vllm_config()
     return (
         vllm_config.compilation_config.pass_config.enable_sequence_parallelism
-        or envs_ascend.VLLM_ASCEND_ENABLE_FLASHCOMM)
+        or envs_ascend.VLLM_ASCEND_ENABLE_FLASHCOMM1
+        # Flash comm 1 should be enabled by env VLLM_ASCEND_ENABLE_FLASHCOMM1
+        # We retain the env VLLM_ASCEND_ENABLE_FLASHCOMM here for backward compatibility.
+        or bool(int(os.getenv("VLLM_ASCEND_ENABLE_FLASHCOMM", '0'))))
+
+
+# TODO remove it after vllm has this func
+def shared_expert_dp_enabled() -> bool:
+    return get_ascend_config().enable_shared_expert_dp or enable_sp()
 
 
 def is_moe_model(vllm_config: VllmConfig):
-    config = vllm_config.model_config.hf_config
-    return any('experts' in key.lower() for key in config.to_dict())
+    global _IS_MOE_MODEL
+    if _IS_MOE_MODEL is None:
+        config = vllm_config.model_config.hf_config
+        _IS_MOE_MODEL = any('experts' in key.lower()
+                            for key in config.to_dict())
+    return _IS_MOE_MODEL
 
 
 def weak_ref_tensor(tensor: Any) -> Any: