[feat] refactored extension module (#5298)

* [feat] refactored extension module

* polish

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extensions/moe/__init__.py

@@ -0,0 +1,3 @@
+from .moe_cuda import MoeCudaExtension
+
+__all__ = ['MoeCudaExtension']

extensions/moe/moe_cuda.py

@@ -0,0 +1,29 @@
+from ..cuda_extension import _CudaExtension
+from ..utils import append_nvcc_threads, get_cuda_cc_flag
+
+
+class MoeCudaExtension(_CudaExtension):
+    def __init__(self):
+        super().__init__(name="moe_cuda")
+
+    def include_dirs(self):
+        ret = [self.csrc_abs_path("cuda/include"), self.get_cuda_home_include()]
+        return ret
+
+    def sources_files(self):
+        ret = [self.csrc_abs_path(fname) for fname in ["cuda/moe_cuda.cpp", "cuda/moe_cuda_kernel.cu"]]
+        return ret
+
+    def cxx_flags(self):
+        return ["-O3"] + self.version_dependent_macros
+
+    def nvcc_flags(self):
+        extra_cuda_flags = [
+            "-U__CUDA_NO_HALF_OPERATORS__",
+            "-U__CUDA_NO_HALF_CONVERSIONS__",
+            "--expt-relaxed-constexpr",
+            "--expt-extended-lambda",
+        ]
+        extra_cuda_flags.extend(get_cuda_cc_flag())
+        ret = ["-O3", "--use_fast_math"] + extra_cuda_flags
+        return append_nvcc_threads(ret)