I found that pypy.jit.backend.test.test_random is failing if I pass --backend=x86 The following patch fixes it for me: --- a/pypy/jit/backend/test/test_random.py +++ b/pypy/jit/backend/test/test_random.py @@ -717,6 +717,7 @@ def test_random_function(BuilderClass=OperationBuilder): r = Random() cpu = get_cpu() + cpu.setup_once() if pytest.config.option.repeat == -1: while 1: check_random_function(cpu, BuilderClass, r) -M-