message: Use LLVM main branch instead of master
diff: @@ -124,7 +124,7 @@ def checkout_LLVM(component, version_LLVM, target_dir, from_validation, verbose)
  # An example of using branch (instead of final tag) is the following (for 9.0):
  # git: "origin/release/9.x"
  if version_LLVM == "trunk":
  - GIT_TAG="master"
  + GIT_TAG="main"
  elif version_LLVM == "11_0":
  GIT_TAG="llvmorg-11.0.0"
  elif version_LLVM == "10_0":
  @@ -145,7 +145,7 @@ def checkout_LLVM(component, version_LLVM, target_dir, from_validation, verbose)
  try_do_LLVM("clone "+component+" from "+GIT_REPO_BASE+" to "+target_dir+" ",
  "git clone "+GIT_REPO_BASE+" "+target_dir,
  from_validation, verbose)
  - if GIT_TAG != "master":
  + if GIT_TAG != "main":
  os.chdir(target_dir)
  try_do_LLVM("switch to "+GIT_TAG+" tag ",
  "git checkout -b "+GIT_TAG+" "+GIT_TAG, from_validation, verbose)
  @@ -892,7 +892,7 @@ def Main():
  error("you ISPC_HOME and your current path are different! (" + os.environ["ISPC_HOME"] + " is not equal to " + os.getcwd() +
  ")\n", 2)
  if options.perf_llvm == True:
  - if options.branch == "master":
  + if options.branch == "main":
  options.branch = "trunk"
  global generator
  if options.generator:
  @@ -1011,7 +1011,7 @@ if __name__ == '__main__':
  run_group = OptionGroup(parser, "Options for validation run",
  "These options must be used with -r option.")
  run_group.add_option('--compare-with', dest='branch',
  - help='set performance reference point. Dafault: master', default="master")
  + help='set performance reference point. Dafault: main', default="main")
  run_group.add_option('--number', dest='number_for_performance',
  help='number of performance runs for each test. Default: 5', default=5)
  run_group.add_option('--notify', dest='notify',
  