Formerly Makerules.~94~

diff --git a/Makerules b/Makerules
index 8fde793..eb0eed5 100644 (file)
--- a/Makerules
+++ b/Makerules
@@ -71,11 +71,6 @@ endif
 +sysdep-includes := $(addprefix -I,$(+sysdep_dirs))
 \f
 # Include any system-specific makefiles.
-# Also generate an ordered list of implicit rules which find the source
-# files in each sysdep directory.  The old method was to use vpath to
-# search all the sysdep directories.  However, that had the problem that a
-# .S file in a later directory would be chosen over a .c file in an earlier
-# directory, which does not preserve the desired sysdeps ordering behavior.
 
 # This is here so things in sysdep Makefiles can easily depend on foo.h as
 # appropriate and not worry about where foo.h comes from, which may be
@@ -89,6 +84,30 @@ ifeq ($(wildcard $(+sysdir_pfx)sysd-Makefile),)
 no_deps=t
 endif
 
+include $(+sysdir_pfx)sysd-Makefile
+$(+sysdir_pfx)sysd-Makefile: $(+sysdir_pfx)config.make $(..)Makerules
+       -@rm -f $@T
+       (for dir in $(sysdirs); do                                            \
+          file=sysdeps/$$dir/Makefile;                                       \
+          if [ -f $(..)$$file ]; then                                        \
+            echo include "\$$(..)$$file";                                    \
+          else true; fi;                                                     \
+        done) > $@T
+       mv $@T $@
+
+# Remove existing files from `before-compile'.  Things are added there when
+# they must exist for dependency generation to work right, but once they
+# exist there is no further need for every single file to depend on them,
+# and those gratuitous dependencies result in many gratuitous
+# recompilations.
+before-compile := $(filter-out $(wildcard $(before-compile)),$(before-compile))
+\f
+# Generate an ordered list of implicit rules which find the source files in
+# each sysdep directory.  The old method was to use vpath to search all the
+# sysdep directories.  However, that had the problem that a .S file in a
+# later directory would be chosen over a .c file in an earlier directory,
+# which does not preserve the desired sysdeps ordering behavior.
+
 # When making the list of .dep files to include, we can't know which ones
 # have source in .s files, and thus do not in fact need a .dep file.
 # So we must define rules to make .dep files for .s files.
@@ -104,14 +123,10 @@ $(objpfx)%.dep: $(objpfx)%.s; $(make-dummy-dep)
 $(objpfx)%.o: $(objpfx)%.c $(before-compile); $(compile-command.c)
 $(objpfx)%.dep: $(objpfx)%.c $(before-compile); $(+make-deps)
 
-include $(+sysdir_pfx)sysd-Makefile
-$(+sysdir_pfx)sysd-Makefile: $(+sysdir_pfx)config.make $(..)Makerules
+include $(+sysdir_pfx)sysd-rules
+$(+sysdir_pfx)sysd-rules: $(+sysdir_pfx)config.make $(..)Makerules
+       -@rm -f $@T
        (for dir in $(sysdirs); do                                            \
-          file=sysdeps/$$dir/Makefile;                                       \
-          if [ -f $(..)$$file ]; then                                        \
-            echo include "\$$(..)$$file";                                    \
-          else true;                                                         \
-          fi;                                                                \
           dir="\$$(sysdep_dir)/$$dir";                                       \
           echo "\$$(objpfx)%.o: $$dir/%.S \$$(before-compile); \
                \$$(compile-command.S)";                                      \
@@ -124,7 +139,8 @@ $(+sysdir_pfx)sysd-Makefile: $(+sysdir_pfx)config.make $(..)Makerules
                \$$(compile-command.c)";                                      \
           echo "\$$(objpfx)%.dep: $$dir/%.c \$$(before-compile); \
                \$$(+make-deps)";                                             \
-        done) > $@
+        done) > $@T
+       mv $@T $@
 
 # The order of these rules is important.
 
@@ -164,8 +180,12 @@ endif
 endif
 
 S-CPPFLAGS = $(asm-CPPFLAGS)
-+make-deps = $(+mkdep) $< $(CPPFLAGS) $($(<:$*.%=%)-CPPFLAGS) | \
-            sed $(sed-remove-objpfx) -e 's,$*\.o,$(@:.dep=.o) $@,' > $@
+define +make-deps
+-@rm -f $@
+$(+mkdep) $< $(CPPFLAGS) $($(<:$*.%=%)-CPPFLAGS) | \
+sed $(sed-remove-objpfx) -e 's,$*\.o,$(@:.dep=.o) $@,' > $(@:.dep=.dtm)
+mv $(@:.dep=.dtm) $@
+endef
 ifneq (,$(objpfx))
 sed-remove-objpfx = -e 's@$(subst @,\@,$(objpfx))@$$(objpfx)@g'
 endif