avoid non deterministic arch order in compilation

import pathlib

import subprocess

import os

from torch.utils import cpp_extension

# Setting this param to a list has a problem of generating

# different compilation commands (with diferent order of architectures)

# and leading to recompilation of fused kernels.

# set it to empty string to avoid recompilation

# and assign arch flags explicity in extra_cuda_cflags below

os.environ["TORCH_CUDA_ARCH_LIST"] = ""

def get_cuda_bare_metal_version(cuda_dir):

    raw_output = subprocess.check_output([cuda_dir + "/bin/nvcc", "-V"], 

                                         universal_newlines=True)