[ROCm] Serving Fails on Radeon Due to AITER Dtype Import (#30952)

Signed-off-by: vllmellm <vllm.ellm@embeddedllm.com>

vllm/_aiter_ops.py

@@ -24,14 +24,13 @@ def is_aiter_found() -> bool:
 # we keep this global outside to not cause torch compile breaks.
 IS_AITER_FOUND = is_aiter_found()
 
-# Can't use dtypes.fp8 directly inside an op
-# because it returns wrong result on gfx942.
-# This is a workaround to get the correct FP8 dtype.
-# This might because that the get_gfx() is wrapped as a custom op.
-if IS_AITER_FOUND:
-    from aiter import dtypes
 
-    AITER_FP8_DTYPE = dtypes.fp8
+def is_aiter_found_and_supported() -> bool:
+    if current_platform.is_rocm() and IS_AITER_FOUND:
+        from vllm.platforms.rocm import on_gfx9
+
+        return on_gfx9()
+    return False
 
 
 def if_aiter_supported(func: Callable) -> Callable:
@@ -43,17 +42,24 @@ def if_aiter_supported(func: Callable) -> Callable:
     def wrapper(*args, **kwargs):
         # checks the platform, device arch and aiter library existence.
 
-        if current_platform.is_rocm() and IS_AITER_FOUND:
+        if is_aiter_found_and_supported():
-            from vllm.platforms.rocm import on_gfx9
+            return func(*args, **kwargs)
-
-            if on_gfx9():
-                return func(*args, **kwargs)
 
         return None
 
     return wrapper
 
 
+# Can't use dtypes.fp8 directly inside an op
+# because it returns wrong result on gfx942.
+# This is a workaround to get the correct FP8 dtype.
+# This might because that the get_gfx() is wrapped as a custom op.
+if is_aiter_found_and_supported():
+    from aiter import dtypes
+
+    AITER_FP8_DTYPE = dtypes.fp8
+
+
 def _rocm_aiter_fused_moe_impl(
     hidden_states: torch.Tensor,
     w1: torch.Tensor,