As the v1 notes (among other things): https://lore.kernel.org/git/cover-0.8-00000000000-20211217T012902Z-avarab@xxxxxxxxx/ This speeds up noop runs of "make" by a lot. After a "make" running a "make -j1" with this is ~1.5 faster than on "master"[2], and around 3x as fast with "make -j1 NO_TCLTK=Y" (the TCL part takes a lot of time, but that's another matter). This v4 re-roll (for v3, see https://lore.kernel.org/git/cover-v3-0.9-00000000000-20220225T090127Z-avarab@xxxxxxxxx/): * The "all" boilerplate goes first now, before "include" * Elaborated on DELETE_ON_ERROR ina commit message. * No longer change a ":=" to "=" while moving code. * Rephrased other commit messages (one of which referred to a function from another future series) * Typo fix in commit message. Ævar Arnfjörð Bjarmason (9): scalar Makefile: use "The default target of..." pattern Makefiles: add "shared.mak", move ".DELETE_ON_ERROR" to it Makefile: disable GNU make built-in wildcard rules Makefile: define $(LIB_H) in terms of $(FIND_SOURCE_FILES) Makefile: move ".SUFFIXES" rule to shared.mak Makefile: move $(comma), $(empty) and $(space) to shared.mak Makefile: add "$(QUIET)" boilerplate to shared.mak Makefile: use $(wspfx) for $(QUIET...) in shared.mak Makefiles: add and use wildcard "mkdir -p" template Documentation/Makefile | 63 ++------------------ Makefile | 118 ++++++++++++-------------------------- config.mak.uname | 1 - contrib/scalar/Makefile | 20 ++----- contrib/scalar/t/Makefile | 3 + shared.mak | 109 +++++++++++++++++++++++++++++++++++ t/Makefile | 3 + t/interop/Makefile | 3 + t/perf/Makefile | 3 + templates/Makefile | 8 +-- 10 files changed, 171 insertions(+), 160 deletions(-) create mode 100644 shared.mak Range-diff against v3: 1: 2404c4d8b96 < -: ----------- scalar Makefile: set the default target after the includes -: ----------- > 1: 26c6bb897cf scalar Makefile: use "The default target of..." pattern 2: 96a490bec54 ! 2: 74692458b70 Makefiles: add "shared.mak", move ".DELETE_ON_ERROR" to it @@ Commit message .DELETE_ON_ERROR, 2021-05-21) for the addition and use of the ".DELETE_ON_ERROR" flag. - This does have the potential downside that if e.g. templates/Makefile - would like to include this "shared.mak" in the future the semantics of - such a Makefile will change, but as noted in the above commits (and - GNU make's own documentation) any such change would be for the better, - so it's safe to do this. + I.e. this changes the behavior of existing rules in the altered + Makefiles (except "Makefile" & "Documentation/Makefile"). I'm + confident that this is safe having read the relevant rules in those + Makfiles, and as the GNU make manual notes that it isn't the default + behavior is out of an abundance of backwards compatibility + caution. From edition 0.75 of its manual, covering GNU make 4.3: - This also doesn't introduce a bug by e.g. having this + [Enabling '.DELETE_ON_ERROR' is] almost always what you want + 'make' to do, but it is not historical practice; so for + compatibility, you must explicitly request it. + + This doesn't introduce a bug by e.g. having this ".DELETE_ON_ERROR" flag only apply to this new shared.mak, Makefiles have no such scoping semantics. + It does increase the danger that any Makefile without an explicit "The + default target of this Makefile is..." snippet to define the default + target as "all" could have its default rule changed if our new + shared.mak ever defines a "real" rule. In subsequent commits we'll be + careful not to do that, and such breakage would be obvious e.g. in the + case of "make -C t". + + We might want to make that less fragile still (e.g. by using + ".DEFAULT_GOAL" as noted in the preceding commit), but for now let's + simply include "shared.mak" without adding that boilerplate to all the + Makefiles that don't have it already. Most of those are already + exposed to that potential caveat e.g. due to including "config.mak*". + Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> ## Documentation/Makefile ## @@ Documentation/Makefile: doc-l10n install-l10n:: ## Makefile ## @@ -+# Import tree-wide shared Makefile behavior and libraries -+include shared.mak -+ # The default target of this Makefile is... all:: ++# Import tree-wide shared Makefile behavior and libraries ++include shared.mak ++ + # Define V=1 to have a more verbose compile. + # + # Define SHELL_PATH to a POSIX shell if your /bin/sh is broken. @@ Makefile: shell_compatibility_test: please_set_SHELL_PATH_to_a_more_modern_shell strip: $(PROGRAMS) git$X $(STRIP) $(STRIP_OPTS) $^ @@ Makefile: shell_compatibility_test: please_set_SHELL_PATH_to_a_more_modern_shell ## contrib/scalar/Makefile ## @@ + # The default target of this Makefile is... + all:: + +# Import tree-wide shared Makefile behavior and libraries +include ../../shared.mak + - QUIET_SUBDIR0 = +$(MAKE) -C # space to separate -C and subdir - QUIET_SUBDIR1 = - + include ../../config.mak.uname + -include ../../config.mak.autogen + -include ../../config.mak ## contrib/scalar/t/Makefile ## @@ 3: 9392e3c3e97 ! 3: 0fbdeeffc7b Makefile: disable GNU make built-in wildcard rules @@ Commit message contents from RCS or SCCS. See [1] for an old mailing list discussion about how to disable these. - The speed-up may wary. I've seen 1-10% depending on the speed of the + The speed-up may vary. I've seen 1-10% depending on the speed of the local disk, caches, -jN etc. Running: strace -f -c -S calls make -j1 NO_TCLTK=Y 4: 07cf9daa9d6 = 4: ea6b835308a Makefile: define $(LIB_H) in terms of $(FIND_SOURCE_FILES) 5: 16f2e3ff35b = 5: c2339694cf7 Makefile: move ".SUFFIXES" rule to shared.mak 6: 1b6ecb27f02 ! 6: 741fdfd48e2 Makefile: move $(comma), $(empty) and $(space) to shared.mak @@ Metadata ## Commit message ## Makefile: move $(comma), $(empty) and $(space) to shared.mak - Move these variables over to the shared.max, we'll make use of them in - a subsequent commit. There was no reason for these to be "simply - expanded variables", so let's use the normal lazy "=" assignment here. + Move these variables over to the shared.mak, we'll make use of them in + a subsequent commit. + + Note that there's reason for these to be "simply expanded variables", + i.e. to use ":=" assignments instead of lazily expanded "=" + assignments. We could use "=", but let's leave this as-is for now for + ease of review. See 425ca6710b2 (Makefile: allow combining UBSan with other sanitizers, 2017-07-15) for the commit that introduced these. @@ shared.mak + +## comma, empty, space: handy variables as these tokens are either +## special or can be hard to spot among other Makefile syntax. -+comma = , -+empty = -+space = $(empty) $(empty) ++comma := , ++empty := ++space := $(empty) $(empty) 7: 471067deefc ! 7: a723cbce270 Makefile: add "$(QUIET)" boilerplate to shared.mak @@ config.mak.uname: vcxproj: ## contrib/scalar/Makefile ## -@@ - # Import tree-wide shared Makefile behavior and libraries - include ../../shared.mak +@@ contrib/scalar/Makefile: include ../../config.mak.uname + -include ../../config.mak.autogen + -include ../../config.mak -QUIET_SUBDIR0 = +$(MAKE) -C # space to separate -C and subdir -QUIET_SUBDIR1 = @@ contrib/scalar/Makefile -endif -endif - - include ../../config.mak.uname - -include ../../config.mak.autogen - -include ../../config.mak + TARGETS = scalar$(X) scalar.o + GITLIBS = ../../common-main.o ../../libgit.a ../../xdiff/lib.a + ## shared.mak ## @@ - comma = , - empty = - space = $(empty) $(empty) + comma := , + empty := + space := $(empty) $(empty) + +### Quieting +## common 8: 510306d2219 ! 8: 3733b0c8df1 Makefile: use $(wspfx) for $(QUIET...) in shared.mak @@ Commit message Makefile: use $(wspfx) for $(QUIET...) in shared.mak Change the mostly move-only change in the preceding commit to use the - $(wspfx) variable for defining the QUIET padding, to guarantee that - it's consistent with the "TRACK_template" template. + $(wspfx) variable for defining the QUIET padding. This refactoring + will make it easier to emit that exact amount of padding in functions + that we might add to shared.mak in the future. - $ make CFLAGS=-I$RANDOM grep.o wspfx='$(space)->' - -> GIT-CFLAGS PARAMETERS (changed) - -> CC grep.o + Such a function is not part of this patch series, but a + "TRACK_template" that I'd like to add as a follow-up to it makes use + of this. Let's make this change now while modifying these QUIET rules + is fresh in our minds. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> ## shared.mak ## -@@ shared.mak: comma = , - empty = - space = $(empty) $(empty) +@@ shared.mak: comma := , + empty := + space := $(empty) $(empty) +## wspfx: the whitespace prefix padding for $(QUIET...) and similarly +## aligned output. 9: 85bb74aa32f = 9: 4cc4aeabb20 Makefiles: add and use wildcard "mkdir -p" template -- 2.35.1.1228.g56895c6ee86
