Re: MPS: native comp

[Andrea Corallo <acorallo@gnu.org>]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Andrea Corallo <acorallo@gnu.org> writes:
>
>> The object we are discussing is part of the class that gets set here:
>> comp.c:5413
>>
>>       for (EMACS_INT i = 0; i < d_vec_len; i++
>>         data_relocs[i] = AREF (comp_u->data_vec, i);
>>
>> This is the action you correctly imagined of "putting them into the
>> machine code".
>
> Thanks!
>
> And data_relocs points into the dylib, I see.
>
>       Lisp_Object *data_relocs = dynlib_sym (handle, DATA_RELOC_SYM);
>
> So, we could make [data_relocs, data_relocs + d_vec_len) an ambig root.
>
> I'm wondering, where is the machine code being patched, if it is? Or
> does it the machine code have an indirection into data_relocs? Because,
> in that case, we could perhaps change the references when objects nove.

For:

test.el =================
;; -*- lexical-binding: t; -*-

(defun foo ()
  "xxx")
=================

The generated code looks like this:

test-a526a80f-f923b2eb.c =====================
[...]

struct Lisp_X *[7] d_reloc;

[...]

extern struct Lisp_X *
F666f6f_foo_0 ()
{

[...]

return d_reloc[(long long)0];
}

[...]
=================

> Do I have to do anything with these
>
>       d_vec_len = XFIXNUM (Flength (comp_u->data_impure_vec));
>       for (EMACS_INT i = 0; i < d_vec_len; i++)
> 	data_imp_relocs[i] = AREF (comp_u->data_impure_vec, i);
>
> ?

Yes I guess the same applies  :)

PS if you are interested we can generate the pesudo C for the code with
emit with something like:

(let ((native-comp-debug 3))
  (native-compile "test.el"))

  Andrea