On 02/03/2022 12:49, Ævar Arnfjörð Bjarmason wrote:
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.
I think this is much clearer now,
Best Wishes
Phillip
+ 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
