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author | Jonathan Nieder <jrnieder@gmail.com> | 2010-01-26 09:52:49 -0600 |
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committer | Jonathan Nieder <jrnieder@gmail.com> | 2010-01-26 10:08:55 -0600 |
commit | dfea575017ddc2ae7c9e8dcb978f4557f07715d3 (patch) | |
tree | 9e1e30e1fe6accd016c8be2b892044148f3acacc /Makefile | |
parent | c373991375a4903dbb9bea69e2ce11ce819253e2 (diff) | |
download | git-dfea575017ddc2ae7c9e8dcb978f4557f07715d3.tar.gz git-dfea575017ddc2ae7c9e8dcb978f4557f07715d3.tar.xz |
Makefile: lazily compute header dependencies
Use the gcc -MMD -MP -MF options to generate dependency rules as
a byproduct when building .o files if the
COMPUTE_HEADER_DEPENDENCIES variable is defined. That variable
is left undefined by default for now.
As each object file is built, write a makefile fragment
containing its dependencies in the deps/ subdirectory of its
containing directory. The deps/ directories should be generated
if they are missing at the start of each build. So let each
object file depend on $(missing_dep_dirs), which lists only the
directories of this kind that are missing to avoid needlessly
regenerating files when the directories' timestamps change.
gcc learned the -MMD -MP -MF options in version 3.0, so most gcc
users should have them by now.
The dependencies this option computes are more specific than the
rough estimates hard-coded in the Makefile, greatly speeding up
rebuilds when only a little-used header file has changed.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Diffstat (limited to 'Makefile')
-rw-r--r-- | Makefile | 49 |
1 files changed, 44 insertions, 5 deletions
@@ -217,6 +217,10 @@ all:: # DEFAULT_EDITOR='~/bin/vi', # DEFAULT_EDITOR='$GIT_FALLBACK_EDITOR', # DEFAULT_EDITOR='"C:\Program Files\Vim\gvim.exe" --nofork' +# +# Define COMPUTE_HEADER_DEPENDENCIES if your compiler supports the -MMD option +# and you want to avoid rebuilding objects when an unrelated header file +# changes. GIT-VERSION-FILE: FORCE @$(SHELL_PATH) ./GIT-VERSION-GEN @@ -1677,14 +1681,48 @@ ASM_SRC := $(wildcard $(OBJECTS:o=S)) ASM_OBJ := $(ASM_SRC:S=o) C_OBJ := $(filter-out $(ASM_OBJ),$(OBJECTS)) +ifdef COMPUTE_HEADER_DEPENDENCIES +dep_dirs := $(addsuffix deps,$(sort $(dir $(OBJECTS)))) +$(dep_dirs): + mkdir -p $@ + +missing_dep_dirs := $(filter-out $(wildcard $(dep_dirs)),$(dep_dirs)) +else +dep_dirs = +missing_dep_dirs = +endif + .SUFFIXES: -$(C_OBJ): %.o: %.c GIT-CFLAGS - $(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) $< +$(C_OBJ): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) + $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $< %.s: %.c GIT-CFLAGS FORCE $(QUIET_CC)$(CC) -S $(ALL_CFLAGS) $< -$(ASM_OBJ): %.o: %.S GIT-CFLAGS - $(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) $< +$(ASM_OBJ): %.o: %.S GIT-CFLAGS $(missing_dep_dirs) + $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $< + +ifdef COMPUTE_HEADER_DEPENDENCIES +# Take advantage of gcc's on-the-fly dependency generation +# See <http://gcc.gnu.org/gcc-3.0/features.html>. +dep_files := $(wildcard $(foreach f,$(OBJECTS),$(dir f)deps/$(notdir $f).d)) +ifneq ($(dep_files),) +include $(dep_files) +endif + +dep_file = $(dir $@)deps/$(notdir $@).d +dep_args = -MF $(dep_file) -MMD -MP +else +dep_args = + +# Dependencies on header files, for platforms that do not support +# the gcc -MMD option. +# +# Dependencies on automatically generated headers such as common-cmds.h +# should _not_ be included here, since they are necessary even when +# building an object for the first time. +# +# XXX. Please check occasionally that these include all dependencies +# gcc detects! $(GIT_OBJS): $(LIB_H) builtin-branch.o builtin-checkout.o builtin-clone.o builtin-reset.o branch.o transport.o: branch.h @@ -1700,10 +1738,10 @@ builtin-pack-objects.o: thread-utils.h http-fetch.o http-walker.o remote-curl.o transport.o walker.o: walker.h http.o http-walker.o http-push.o remote-curl.o: http.h - xdiff-interface.o $(XDIFF_OBJS): \ xdiff/xinclude.h xdiff/xmacros.h xdiff/xdiff.h xdiff/xtypes.h \ xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h +endif exec_cmd.s exec_cmd.o: ALL_CFLAGS += \ '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' \ @@ -2011,6 +2049,7 @@ clean: $(RM) $(ALL_PROGRAMS) $(BUILT_INS) git$X $(RM) $(TEST_PROGRAMS) $(RM) -r bin-wrappers + $(RM) -r $(dep_dirs) $(RM) *.spec *.pyc *.pyo */*.pyc */*.pyo common-cmds.h TAGS tags cscope* $(RM) -r autom4te.cache $(RM) config.log config.mak.autogen config.mak.append config.status config.cache |