GSOC 2019: Nuitka all built-ins optimized

Project description: Nuitka has support for many built-ins, e.g. len already, which means dedicated C code, compile time evaluation, type shapes produced (in this case an int), but there are some notable exceptions, e.g. enumerate where we know types too, that are still missing, but definitely can have high performance impact on some loops.

Your task would be to immitate existing built-in codes to achieve a complete support for ultimately all C built-ins. The first step would be to identify which ones are missing (by means of a warning added), then to find out in test runs of the test suites, which ones are warned about, and to resolve as many of those as possible. It is assumed that all should be possible.

Skills: Python and C programming, platform wouldn’t matter

[kayhayen]

As you can see, this is going to give you a nice tour of Nuitka from optimization to code generation, and across various built-ins you may not even know exist, even if you are proficient at Python. I sure didn’t know all of those implemented so far.

[kayhayen]

@bksahu So this is an example of expected effect for generated C code:

Using this test program:

def f():
    x = something()
    return len(x)

-        PyObject *tmp_called_name_2;
-        PyObject *tmp_args_element_name_1;
-        tmp_called_name_2 = LOOKUP_BUILTIN( const_str_plain_len );
-        assert( tmp_called_name_2 != NULL );
+        PyObject *tmp_len_arg_1;
         CHECK_OBJECT( var_x );
-        tmp_args_element_name_1 = var_x;
-        frame_8b78d490904d40bde1d1d570167070ef->m_frame.f_lineno = 4;
-        {
-            PyObject *call_args[] = { tmp_args_element_name_1 };
-            tmp_return_value = CALL_FUNCTION_WITH_ARGS1( tmp_called_name_2, call_args );
-        }
-
+        tmp_len_arg_1 = var_x;
+        tmp_return_value = BUILTIN_LEN( tmp_len_arg_1 );

I got that by disabling the len built-in call optimization, and it shows that instead of calling the built-in name len as a generic function call, we have the dedicated helper BUILTIN_LEN being called.

That is the kind of difference this is about when facing C code. As you can see, this code is not only simpler, but BUILTIN_LEN will be visible to the linker for link time optimization (LTO) once we have that, and can become amazingly faster instead of a relatively generic Python call.