Fix error message on TORCH_CUDA_ARCH_LIST (vllm-project#1239)

Co-authored-by: Yunfeng Bai <yunfeng.bai@scale.com>

setup.py

@@ -13,7 +13,7 @@
 ROOT_DIR = os.path.dirname(__file__)
 
 # Supported NVIDIA GPU architectures.
-SUPPORTED_ARCHS = ["7.0", "7.5", "8.0", "8.6", "8.9", "9.0"]
+SUPPORTED_ARCHS = {"7.0", "7.5", "8.0", "8.6", "8.9", "9.0"}
 
 # Compiler flags.
 CXX_FLAGS = ["-g", "-O2", "-std=c++17"]
@@ -49,19 +49,32 @@ def get_torch_arch_list() -> Set[str]:
     # and executed on the 8.6 or newer architectures. While the PTX code will
     # not give the best performance on the newer architectures, it provides
     # forward compatibility.
-    valid_arch_strs = SUPPORTED_ARCHS + [s + "+PTX" for s in SUPPORTED_ARCHS]
-    arch_list = os.environ.get("TORCH_CUDA_ARCH_LIST", None)
-    if arch_list is None:
+    env_arch_list = os.environ.get("TORCH_CUDA_ARCH_LIST", None)
+    if env_arch_list is None:
         return set()
 
     # List are separated by ; or space.
-    arch_list = arch_list.replace(" ", ";").split(";")
-    for arch in arch_list:
-        if arch not in valid_arch_strs:
-            raise ValueError(
-                f"Unsupported CUDA arch ({arch}). "
-                f"Valid CUDA arch strings are: {valid_arch_strs}.")
-    return set(arch_list)
+    torch_arch_list = set(env_arch_list.replace(" ", ";").split(";"))
+    if not torch_arch_list:
+        return set()
+
+    # Filter out the invalid architectures and print a warning.
+    valid_archs = SUPPORTED_ARCHS.union({s + "+PTX" for s in SUPPORTED_ARCHS})
+    arch_list = torch_arch_list.intersection(valid_archs)
+    # If none of the specified architectures are valid, raise an error.
+    if not arch_list:
+        raise RuntimeError(
+            "None of the CUDA architectures in `TORCH_CUDA_ARCH_LIST` env "
+            f"variable ({env_arch_list}) is supported. "
+            f"Supported CUDA architectures are: {valid_archs}.")
+    invalid_arch_list = torch_arch_list - valid_archs
+    if invalid_arch_list:
+        warnings.warn(
+            f"Unsupported CUDA architectures ({invalid_arch_list}) are "
+            "excluded from the `TORCH_CUDA_ARCH_LIST` env variable "
+            f"({env_arch_list}). Supported CUDA architectures are: "
+            f"{valid_archs}.")
+    return arch_list
 
 
 # First, check the TORCH_CUDA_ARCH_LIST environment variable.
@@ -81,7 +94,7 @@ def get_torch_arch_list() -> Set[str]:
 if not compute_capabilities:
     # If no GPU is specified nor available, add all supported architectures
     # based on the NVCC CUDA version.
-    compute_capabilities = set(SUPPORTED_ARCHS)
+    compute_capabilities = SUPPORTED_ARCHS.copy()
     if nvcc_cuda_version < Version("11.1"):
         compute_capabilities.remove("8.6")
     if nvcc_cuda_version < Version("11.8"):