Speeding up the bootstrap build - a quick hack.

[Alan Mackenzie <acm@muc.de>]

Hello, Emacs.

I sense some unhappiness about emacs-devel occasioned by my branch
scratch/correct-warning-pos, because the build on the branch is a little
slower.

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.

With the amended makefile, my build took 6m 7s.  Before the amendment,
it was around 7m 16s.  This is a saving of around 15%.

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.

Enjoy!


diff --git a/lisp/Makefile.in b/lisp/Makefile.in
index 3a72034463..b81337d2f3 100644
--- a/lisp/Makefile.in
+++ b/lisp/Makefile.in
@@ -85,6 +85,14 @@ BYTE_COMPILE_FLAGS =
 # the compiler (so its compilation does not speed up subsequent compilations),
 # it's only placed here so as to speed up generation of the loaddefs.el file.
 
+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    \
@@ -298,22 +306,30 @@ $(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:
+	$(AM_V_ELC)$(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 '(\".elc0\" \".elc\" \".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)


-- 
Alan Mackenzie (Nuremberg, Germany).