[Utils] Add an option to specify number of cores to use in creduce-clang-crash.py

[rnk]

clang/utils/creduce-clang-crash.py

81

I think we should try to pick a good default here. I think we can do better than creduce's default of 4 or whatever it is. I think max(4, os.cpu_count() / 2) might be a good guess.

[zequanwu]

Address comment, using max(4, multiprocessing.cpu_count() / 2) because os.cpu_count is not available in python2.

[thakis]

In D97098#2579620, @zequanwu wrote:

Address comment, using max(4, multiprocessing.cpu_count() / 2) because os.cpu_count is not available in python2.

We require py3 these days, so it's ok to assume it.

[thakis]

But lgtm either way.

[rnk]

lgtm

clang/utils/creduce-clang-crash.py

def quote_cmd(cmd):
   return ' '.join(pipes.quote(arg) for arg in cmd)
 
 def write_to_script(text, filename):
   with open(filename, 'w') as f:
     f.write(text)
   os.chmod(filename, os.stat(filename).st_mode | stat.S_IEXEC)
 
 class Reduce(object):
-  def __init__(self, crash_script, file_to_reduce):
+  def __init__(self, crash_script, file_to_reduce, core_number):
     crash_script_name, crash_script_ext = os.path.splitext(crash_script)
     file_reduce_name, file_reduce_ext = os.path.splitext(file_to_reduce)
 
     self.testfile = file_reduce_name + '.test.sh'
     self.crash_script = crash_script_name + '.reduced' + crash_script_ext
     self.file_to_reduce = file_reduce_name + '.reduced' + file_reduce_ext
     shutil.copy(file_to_reduce, self.file_to_reduce)
 
     self.clang = clang_cmd
     self.clang_args = []
     self.expected_output = []
     self.needs_stack_trace = False
     self.creduce_flags = ["--tidy"]
+    if core_number > 0:
+      self.creduce_flags = ["--n", str(core_number)]
 
     self.read_clang_args(crash_script, file_to_reduce)
     self.read_expected_output()
 
   def get_crash_cmd(self, cmd=None, args=None, filename=None):
     if not cmd:
       cmd = self.clang
     if not args:
def main():
   parser.add_argument('--llvm-bin', dest='llvm_bin', type=str,
                       help="Path to the LLVM bin directory.")
   parser.add_argument('--clang', dest='clang', type=str,
                       help="The path to the `clang` executable. "
                       "By default uses the llvm-bin directory.")
   parser.add_argument('--creduce', dest='creduce', type=str,
                       help="The path to the `creduce` executable. "
                       "Required if `creduce` is not in PATH environment.")
+  parser.add_argument('--n', dest='core_number', type=int, default=0,
+                      help="Number of cores to use.")
   parser.add_argument('-v', '--verbose', action='store_true')
   args = parser.parse_args()
 
   verbose = args.verbose
   llvm_bin = os.path.abspath(args.llvm_bin) if args.llvm_bin else None
   creduce_cmd = check_cmd('creduce', None, args.creduce)
   clang_cmd = check_cmd('clang', llvm_bin, args.clang)
+  core_number = args.core_number
 
   crash_script = check_file(args.crash_script[0])
   file_to_reduce = check_file(args.file_to_reduce[0])
 
-  r = Reduce(crash_script, file_to_reduce)
+  r = Reduce(crash_script, file_to_reduce, core_number)
 
   r.simplify_clang_args()
   r.write_interestingness_test()
   r.clang_preprocess()
   r.run_creduce()
   r.reduce_clang_args()
 
 if __name__ == '__main__':
   main()