Re: Speeding up the bootstrap build - a quick hack.

[Stefan Monnier]

> The following may go some way to fixing this slowdown.  Its idea is to
> build the lisp directory first by compiling the byte compiler and then
> using this to build the native compiler, rather than building the native
> compiler directly from interpreted list.

Thanks, that's pretty much what I suggested we should do (tho I wasn't
too sure *how* to do that ;-)

> This patch is at the stage of being a crude hack, and it has been tried
> only on GNU.  It might work on other systems, though.

It looks pretty good and clean, actually.

I of course have some comments/questions:

> +COMPILE_ZEROTH = \
> +     $(lisp)/emacs-lisp/macroexp.elc0 \
> +     $(lisp)/emacs-lisp/cconv.elc0 \
> +     $(lisp)/emacs-lisp/byte-opt.elc0 \
> +     $(lisp)/emacs-lisp/bytecomp.elc0 \
> +     $(lisp)/emacs-lisp/comp-cstr.elc0 \
> +     $(lisp)/emacs-lisp/comp.elc0
> +
>  COMPILE_FIRST = \
>       $(lisp)/emacs-lisp/macroexp.elc \
>       $(lisp)/emacs-lisp/cconv.elc    \

Can't COMPILE_ZEROTH be made directly from COMPILE_FIRST so we don't
need to maintain two different lists?

>  # An old-fashioned suffix rule, which, according to the GNU Make manual,
>  # cannot have prerequisites.
>  ifeq ($(HAVE_NATIVE_COMP),yes)
> -.el.elc:
> +.el.elc0:
> +     $(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) \
> +     --exec "(setq load-suffixes '(\".elc0\" \".el\"))" \
> +     -f batch-byte-compile $<
> +     mv $<c $@

The indentation looks wrong here, tho maybe it's a question of taste
(or it's a problem in the TAB/SPC transfer through email).

> +%.elc : %.el $(COMPILE_ZEROTH)
>       $(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) \
> +     --exec "(setq load-suffixes '(\".elc0\" \".elc\" \".el\"))" \
>       -l comp -f batch-byte+native-compile $<

Shouldn't this list have `.elc` before `.elc0` so we use the
native-compiled compiler when available?

> -.PHONY: compile-first compile-main compile compile-always
> +.PHONY: compile-zeroth compile-first compile-main compile compile-always
>  
> -compile-first: $(COMPILE_FIRST)
> +compile-zeroth: $(COMPILE_ZEROTH)
> +compile-first: compile-zeroth $(COMPILE_FIRST)

Is this necessary, or is it just helpful to debug the Makefile?


        Stefan