[GRASS5] dependencies issue for recompilation

[Glynn Clements]

Markus Neteler wrote:

> we discovered that two subsequent full compilation
> runs lead to a significant recompilation. We would
> expect that nearly nothing is recompiled in the second
> run. This seems to be a new "feature" - any ideas
> where to look for that?

I've committed this fix to CVS:

	Index: include/Make/Rules.make
	===================================================================
	RCS file: /grassrepository/grass6/include/Make/Rules.make,v
	retrieving revision 1.31
	diff -u -r1.31 Rules.make
	--- include/Make/Rules.make	4 Nov 2005 08:35:06 -0000	1.31
	+++ include/Make/Rules.make	10 Mar 2006 00:37:26 -0000
	@@ -14,7 +14,7 @@
	 NLS_CFLAGS=$(GETHOSTNAME) $(ZLIBINCPATH) $(PICFLAGS) $(DEFS)
	 
	 # default cc rules
	-$(OBJDIR)/%.o : %.c $(DEPENDENCIES) $(LOCAL_HEADERS) 
	+$(OBJDIR)/%.o : %.c $(LOCAL_HEADERS) 
	 	@test -d $(OBJDIR) || mkdir $(OBJDIR)	
	 	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $(NLS_CFLAGS) $(EXTRA_INC) $(INC) \
	 		-o $(OBJDIR)/$*.o -c $*.c

$(DEPENDENCIES) is the list of *libraries* on which an executable
depends.

Because libgis is rebuilt each time, anything which lists a dependency
upon $(GISDEP) (i.e. almost everything) will be re-compiled from
scratch.

The fact that libgis is rebuilt each time means that modules still
have to be re-linked, but that should be a lot quicker than
re-compiling.

The reason that libgis is rebuilt each time is that version.h is
re-installed (to dist.<arch>/include/grass) on each run, gisinit.o has
a dependency upon version.h, and libgis has a dependency upon
gisinit.o.

To eliminate the re-linking, I've committed this:

	Index: lib/gis/Makefile
	===================================================================
	RCS file: /grassrepository/grass6/lib/gis/Makefile,v
	retrieving revision 1.43
	diff -u -r1.43 Makefile
	--- lib/gis/Makefile	7 Feb 2006 13:15:57 -0000	1.43
	+++ lib/gis/Makefile	10 Mar 2006 01:07:49 -0000
	@@ -10,8 +10,7 @@
	 	EXTRA_CFLAGS = -D_FILE_OFFSET_BITS=64
	 endif
	 
	-default: $(ARCH_INCDIR)/version.h \
	-	lib \
	+default: lib \
	 	$(FMODE_OBJ) \
	 	$(ETC)/ellipse.table \
	 	$(ETC)/datum.table \
	@@ -27,9 +26,6 @@
	 	echo -e "#include <stdlib.h>\n#include <fcntl.h>\n#undef _fmode\nint _fmode = _O_BINARY;" > $(OBJDIR)/fmode.c
	 	$(CC) $(CFLAGS) $(INC) -o $(FMODE_OBJ) -c $(OBJDIR)/fmode.c
	 
	-$(ARCH_INCDIR)/version.h:
	-	echo 'static char *GRASS_VERSION_STRING = "@(#) GRASS $(GRASS_VERSION_NUMBER) ($(GRASS_VERSION_DATE))";' > $@
	-
	 $(ETC)/ellipse.table: ellipse.table
	 	rm -f $@
	 	$(INSTALL) -m 644 $? $@
	@@ -113,7 +109,6 @@
	 $(OBJDIR)/get_row.o: G.h
	 $(OBJDIR)/get_window.o: G.h
	 $(OBJDIR)/gisinit.o: G.h
	-$(OBJDIR)/gisinit.o: $(ARCH_INCDIR)/version.h
	 $(OBJDIR)/maskfd.o: G.h
	 $(OBJDIR)/opencell.o: G.h
	 $(OBJDIR)/put_row.o: G.h

The actual fix is simply the removal of the dependency at the bottom. 
The first two parts are removed because they are redundant; the
configure script generates include/version.h, and the "headers" rule
in include/Makefile installs it in $(ARCH_INCDIR).

There are still a few modules which are re-linked:

1. XDRIVER, due to winname.h being updated on each run.

2. The various mod* programs from r.support, because they are *moved*
to $(ETC) rather than installed.

3. tools/timer, because the target is $(PGM) but the rule creates
$(ETC)/$(PGM), so $(PGM) will never exist.

I'll fix those shortly.

-- 
Glynn Clements <glynn at gclements.plus.com>