Add more CUDA architectures for PyPi package (#2427)

* add cuda sm 90

* add more archs

setup.py

@@ -44,6 +44,8 @@ def get_version():
 
 
 build_stage = int(os.environ.get("MLX_BUILD_STAGE", 0))
+build_macos = platform.system() == "Darwin"
+build_cuda = "MLX_BUILD_CUDA=ON" in os.environ.get("CMAKE_ARGS", "")
 
 
 # A CMakeExtension needs a sourcedir instead of a file list.
@@ -85,6 +87,11 @@ class CMakeBuild(build_ext):
             "-DMLX_BUILD_EXAMPLES=OFF",
             f"-DMLX_PYTHON_BINDINGS_OUTPUT_DIRECTORY={extdir}{os.sep}",
         ]
+        if build_stage == 2 and build_cuda:
+            # Last arch is always real and virtual for forward-compatibility
+            cuda_archs = ";".join(("70-real", "80-real", "90-real", "100-real", "120"))
+            cmake_args += [f"-DMLX_CUDA_ARCHITECTURES={cuda_archs}"]
+
         # Some generators require explcitly passing config when building.
         build_args = ["--config", cfg]
         # Adding CMake arguments set as environment variable
@@ -95,7 +102,7 @@ class CMakeBuild(build_ext):
         # Pass version to C++
         cmake_args += [f"-DMLX_VERSION={self.distribution.get_version()}"]  # type: ignore[attr-defined]
 
-        if platform.system() == "Darwin":
+        if build_macos:
             # Cross-compile support for macOS - respect ARCHFLAGS if set
             archs = re.findall(r"-arch (\S+)", os.environ.get("ARCHFLAGS", ""))
             if archs:
@@ -202,9 +209,6 @@ if __name__ == "__main__":
         ],
     )
 
-    build_macos = platform.system() == "Darwin"
-    build_cuda = "MLX_BUILD_CUDA=ON" in os.environ.get("CMAKE_ARGS", "")
-
     version = get_version()
 
     _setup = partial(