Before:
  runtime! ale_linters/llvm/llc.vim

Execute(llc handler should parse errors output for STDIN):
  AssertEqual
  \ [
  \   {
  \      'lnum': 10,
  \      'col': 7,
  \      'text': "error: value doesn't match function result type 'i32'",
  \      'type': 'E',
  \   },
  \   {
  \      'lnum': 10,
  \      'col': 13,
  \      'text': "error: use of undefined value '@foo'",
  \      'type': 'E',
  \   },
  \ ],
  \ ale_linters#llvm#llc#HandleErrors(bufnr(''), [
  \   "llc: <stdin>:10:7: error: value doesn't match function result type 'i32'",
  \   'ret i64 0',
  \   '    ^',
  \   '',
  \   "llc: <stdin>:10:13: error: use of undefined value '@foo'",
  \   'call void @foo(i64 %0)',
  \   '          ^',
  \ ])

Execute(llc handler should parse errors output for some file):
  call ale#test#SetFilename('test.ll')
  AssertEqual
  \ [
  \   {
  \      'lnum': 10,
  \      'col': 7,
  \      'text': "error: value doesn't match function result type 'i32'",
  \      'type': 'E',
  \   },
  \   {
  \      'lnum': 10,
  \      'col': 13,
  \      'text': "error: use of undefined value '@foo'",
  \      'type': 'E',
  \   },
  \ ],
  \ ale_linters#llvm#llc#HandleErrors(bufnr(''), [
  \   "llc: /path/to/test.ll:10:7: error: value doesn't match function result type 'i32'",
  \   'ret i64 0',
  \   '    ^',
  \   '',
  \   "llc: /path/to/test.ll:10:13: error: use of undefined value '@foo'",
  \   'call void @foo(i64 %0)',
  \   '          ^',
  \ ])