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

[Alan Mackenzie]

Hello, Stefan.

Thanks for the detailled feedback.

On Mon, Jan 17, 2022 at 15:55:26 -0500, Stefan Monnier wrote:
> > 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.

Oh, thanks!

> 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?

It can, yes.  There's no reason for them to be different files at the
moment, so I've done this.

> >  # 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).

I think it's just the TAB going to column 8 whatever.

> > +%.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?

I think so, yes.  I've changed this now.

> > -.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?

I'm not sure.  I'm a little confused, still.

Could I ask you to give the latest version, below, a quick eyeballing,
please?  Maybe I could install this.



diff --git a/lisp/Makefile.in b/lisp/Makefile.in
index 3a72034463..7df58af05e 100644
--- a/lisp/Makefile.in
+++ b/lisp/Makefile.in
@@ -96,6 +96,10 @@ COMPILE_FIRST +=
 endif
 COMPILE_FIRST += $(lisp)/emacs-lisp/autoload.elc
 
+ifeq ($(HAVE_NATIVE_COMP),yes)
+COMPILE_ZEROTH = $(COMPILE_FIRST:.elc=.elc0)
+endif
+
 # Files to compile early in compile-main.  Works around bug#25556.
 MAIN_FIRST = ./emacs-lisp/eieio.el ./emacs-lisp/eieio-base.el \
   ./cedet/semantic/db.el ./emacs-lisp/cconv.el
@@ -298,22 +302,30 @@ $(THEFILE)n:
 # subdirectories, to make sure require's and load's in the files being
 # compiled find the right files.
 
-.SUFFIXES: .elc .el
+.SUFFIXES: .elc0 .elc .el
 
 # An old-fashioned suffix rule, which, according to the GNU Make manual,
 # cannot have prerequisites.
 ifeq ($(HAVE_NATIVE_COMP),yes)
-.el.elc:
+.el.elc0:
+       $(AM_V_ELC0)$(emacs) $(BYTE_COMPILE_FLAGS) \
+       --exec "(setq load-suffixes '(\".elc0\" \".el\"))" \
+       -f batch-byte-compile $<
+       mv $<c $@
+
+%.elc: %.el $(COMPILE_ZEROTH)
        $(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) \
+       --exec "(setq load-suffixes '(\".elc\" \".elc0\" \".el\"))" \
        -l comp -f batch-byte+native-compile $<
 else
 .el.elc:
        $(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) -f batch-byte-compile $<
 endif
 
-.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)
 
 # In 'compile-main' we could directly do
 #    ... | xargs $(MAKE)
@@ -492,7 +504,7 @@ $(CAL_DIR)/hol-loaddefs.el:
 .PHONY: bootstrap-clean distclean maintainer-clean
 
 bootstrap-clean:
-       find $(lisp) -name '*.elc' $(FIND_DELETE)
+       find $(lisp) \( -name '*.elc' -o -name '*.elc0' \) $(FIND_DELETE)
        rm -f $(AUTOGENEL)
 
 distclean:
diff --git a/src/verbose.mk.in b/src/verbose.mk.in
index e3f5678303..a8081ee55a 100644
--- a/src/verbose.mk.in
+++ b/src/verbose.mk.in
@@ -26,6 +26,7 @@ AM_V_CC =
 AM_V_CXX =
 AM_V_CCLD =
 AM_V_CXXLD =
+AM_V_ELC0 =
 AM_V_ELC =
 AM_V_ELN =
 AM_V_GEN =
@@ -41,13 +42,16 @@ AM_V_CCLD    = @$(info $   CCLD     $@)
 AM_V_CXXLD   = @$(info $   CXXLD    $@)
 ifeq ($(HAVE_NATIVE_COMP),yes)
 ifeq ($(NATIVE_DISABLED),1)
+AM_V_ELC0    = @$(info $   ELC0     $@)
 AM_V_ELC     = @$(info $   ELC      $@)
 AM_V_ELN =
 else
+AM_V_ELC0    = @$(info $   ELC0     $@)
 AM_V_ELC     = @$(info $   ELC+ELN  $@)
 AM_V_ELN     = @$(info $   ELN      $@)
 endif
 else
+AM_V_ELC0 =
 AM_V_ELC     = @$(info $   ELC      $@)
 AM_V_ELN =
 endif


>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).