git/shared.mak

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2.9 KiB
Makefile
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### Remove GNU make implicit rules
## This speeds things up since we don't need to look for and stat() a
## "foo.c,v" every time a rule referring to "foo.c" is in play. See
## "make -p -f/dev/null | grep ^%::'".
%:: %,v
%:: RCS/%,v
%:: RCS/%
%:: s.%
%:: SCCS/s.%
Makefile: move ".SUFFIXES" rule to shared.mak This was added in 30248886ce8 (Makefile: disable default implicit rules, 2010-01-26), let's move it to the top of "shared.mak" so it'll apply to all our Makefiles. This doesn't benefit the main Makefile at all, since it already had the rule, but since we're including shared.mak in other Makefiles starts to benefit them. E.g. running the 'man" target is now faster: $ git -c hyperfine.hook.setup= hyperfine -L rev HEAD~1,HEAD~0 -s 'make -C Documentation man' 'make -C Documentation -j1 man' Benchmark 1: make -C Documentation -j1 man' in 'HEAD~1 Time (mean ± σ): 121.7 ms ± 8.8 ms [User: 105.8 ms, System: 18.6 ms] Range (min … max): 112.8 ms … 148.4 ms 26 runs Benchmark 2: make -C Documentation -j1 man' in 'HEAD~0 Time (mean ± σ): 97.5 ms ± 8.0 ms [User: 80.1 ms, System: 20.1 ms] Range (min … max): 89.8 ms … 111.8 ms 32 runs Summary 'make -C Documentation -j1 man' in 'HEAD~0' ran 1.25 ± 0.14 times faster than 'make -C Documentation -j1 man' in 'HEAD~1' The reason for that can be seen when comparing that run with "--debug=a". Without this change making a target like "git-status.1" will cause "make" to consider not only "git-status.txt", but "git-status.txt.o", as well as numerous other implicit suffixes such as ".c", ".cc", ".cpp" etc. See [1] for a more detailed before/after example. So this is causing us to omit a bunch of work we didn't need to do. For making "git-status.1" the "--debug=a" output is reduced from ~140k lines to ~6k. 1. https://lore.kernel.org/git/220222.86bkyz875k.gmgdl@evledraar.gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-03 19:04:16 +03:00
## Likewise delete default $(SUFFIXES). See:
##
## info make --index-search=.SUFFIXES
.SUFFIXES:
Makefiles: add "shared.mak", move ".DELETE_ON_ERROR" to it We have various behavior that's shared across our Makefiles, or that really should be (e.g. via defined templates). Let's create a top-level "shared.mak" to house those sorts of things, and start by adding the ".DELETE_ON_ERROR" flag to it. See my own 7b76d6bf221 (Makefile: add and use the ".DELETE_ON_ERROR" flag, 2021-06-29) and db10fc6c09f (doc: simplify Makefile using .DELETE_ON_ERROR, 2021-05-21) for the addition and use of the ".DELETE_ON_ERROR" flag. 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: [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@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-03 19:04:13 +03:00
### Flags affecting all rules
# A GNU make extension since gmake 3.72 (released in late 1994) to
# remove the target of rules if commands in those rules fail. The
# default is to only do that if make itself receives a signal. Affects
# all targets, see:
#
# info make --index-search=.DELETE_ON_ERROR
.DELETE_ON_ERROR:
### Global variables
## 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) $(empty)
### Quieting
## common
QUIET_SUBDIR0 = +$(MAKE) -C # space to separate -C and subdir
QUIET_SUBDIR1 =
ifneq ($(findstring w,$(MAKEFLAGS)),w)
PRINT_DIR = --no-print-directory
else # "make -w"
NO_SUBDIR = :
endif
ifneq ($(findstring s,$(MAKEFLAGS)),s)
ifndef V
## common
QUIET_SUBDIR0 = +@subdir=
QUIET_SUBDIR1 = ;$(NO_SUBDIR) echo ' ' SUBDIR $$subdir; \
$(MAKE) $(PRINT_DIR) -C $$subdir
QUIET = @
QUIET_GEN = @echo ' ' GEN $@;
QUIET_MKDIR_P_PARENT = @echo ' ' MKDIR -p $(@D);
Makefiles: add and use wildcard "mkdir -p" template Add a template to do the "mkdir -p" of $(@D) (the parent dir of $@) for us, and use it for the "make lint-docs" targets I added in 8650c6298c1 (doc lint: make "lint-docs" non-.PHONY, 2021-10-15). As seen in 4c64fb5aad9 (Documentation/Makefile: fix lint-docs mkdir dependency, 2021-10-26) maintaining these manual lists of parent directory dependencies is fragile, in addition to being obviously verbose. I used this pattern at the time because I couldn't find another method than "order-only" prerequisites to avoid doing a "mkdir -p $(@D)" for every file being created, which as noted in [1] would be significantly slower. But as it turns out we can use this neat trick of only doing a "mkdir -p" if the $(wildcard) macro tells us the path doesn't exist. A re-run of a performance test similar to that noted downthread of [1] in [2] shows that this is faster, in addition to being less verbose and more reliable (this uses my "git-hyperfine" thin wrapper for "hyperfine"[3]): $ git -c hyperfine.hook.setup= hyperfine -L rev HEAD~1,HEAD~0 -s 'make -C Documentation lint-docs' -p 'rm -rf Documentation/.build' 'make -C Documentation -j1 lint-docs' Benchmark 1: make -C Documentation -j1 lint-docs' in 'HEAD~1 Time (mean ± σ): 2.914 s ± 0.062 s [User: 2.449 s, System: 0.489 s] Range (min … max): 2.834 s … 3.020 s 10 runs Benchmark 2: make -C Documentation -j1 lint-docs' in 'HEAD~0 Time (mean ± σ): 2.315 s ± 0.062 s [User: 1.950 s, System: 0.386 s] Range (min … max): 2.229 s … 2.397 s 10 runs Summary 'make -C Documentation -j1 lint-docs' in 'HEAD~0' ran 1.26 ± 0.04 times faster than 'make -C Documentation -j1 lint-docs' in 'HEAD~1' So let's use that pattern both for the "lint-docs" target, and a few miscellaneous other targets. This method of creating parent directories is explicitly racy in that we don't know if we're going to say always create a "foo" followed by a "foo/bar" under parallelism, or skip the "foo" because we created "foo/bar" first. In this case it doesn't matter for anything except that we aren't guaranteed to get the same number of rules firing when running make in parallel. 1. https://lore.kernel.org/git/211028.861r45y3pt.gmgdl@evledraar.gmail.com/ 2. https://lore.kernel.org/git/211028.86o879vvtp.gmgdl@evledraar.gmail.com/ 3. https://gitlab.com/avar/git-hyperfine/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-03 19:04:19 +03:00
## Used in "Makefile"
QUIET_CC = @echo ' ' CC $@;
QUIET_AR = @echo ' ' AR $@;
QUIET_LINK = @echo ' ' LINK $@;
QUIET_BUILT_IN = @echo ' ' BUILTIN $@;
QUIET_LNCP = @echo ' ' LN/CP $@;
QUIET_XGETTEXT = @echo ' ' XGETTEXT $@;
QUIET_MSGFMT = @echo ' ' MSGFMT $@;
QUIET_GCOV = @echo ' ' GCOV $@;
QUIET_SP = @echo ' ' SP $<;
QUIET_HDR = @echo ' ' HDR $(<:hcc=h);
QUIET_RC = @echo ' ' RC $@;
QUIET_SPATCH = @echo ' ' SPATCH $<;
## Used in "Documentation/Makefile"
QUIET_ASCIIDOC = @echo ' ' ASCIIDOC $@;
QUIET_XMLTO = @echo ' ' XMLTO $@;
QUIET_DB2TEXI = @echo ' ' DB2TEXI $@;
QUIET_MAKEINFO = @echo ' ' MAKEINFO $@;
QUIET_DBLATEX = @echo ' ' DBLATEX $@;
QUIET_XSLTPROC = @echo ' ' XSLTPROC $@;
QUIET_GEN = @echo ' ' GEN $@;
QUIET_STDERR = 2> /dev/null
QUIET_LINT_GITLINK = @echo ' ' LINT GITLINK $<;
QUIET_LINT_MANSEC = @echo ' ' LINT MAN SEC $<;
QUIET_LINT_MANEND = @echo ' ' LINT MAN END $<;
export V
endif
endif
Makefiles: add and use wildcard "mkdir -p" template Add a template to do the "mkdir -p" of $(@D) (the parent dir of $@) for us, and use it for the "make lint-docs" targets I added in 8650c6298c1 (doc lint: make "lint-docs" non-.PHONY, 2021-10-15). As seen in 4c64fb5aad9 (Documentation/Makefile: fix lint-docs mkdir dependency, 2021-10-26) maintaining these manual lists of parent directory dependencies is fragile, in addition to being obviously verbose. I used this pattern at the time because I couldn't find another method than "order-only" prerequisites to avoid doing a "mkdir -p $(@D)" for every file being created, which as noted in [1] would be significantly slower. But as it turns out we can use this neat trick of only doing a "mkdir -p" if the $(wildcard) macro tells us the path doesn't exist. A re-run of a performance test similar to that noted downthread of [1] in [2] shows that this is faster, in addition to being less verbose and more reliable (this uses my "git-hyperfine" thin wrapper for "hyperfine"[3]): $ git -c hyperfine.hook.setup= hyperfine -L rev HEAD~1,HEAD~0 -s 'make -C Documentation lint-docs' -p 'rm -rf Documentation/.build' 'make -C Documentation -j1 lint-docs' Benchmark 1: make -C Documentation -j1 lint-docs' in 'HEAD~1 Time (mean ± σ): 2.914 s ± 0.062 s [User: 2.449 s, System: 0.489 s] Range (min … max): 2.834 s … 3.020 s 10 runs Benchmark 2: make -C Documentation -j1 lint-docs' in 'HEAD~0 Time (mean ± σ): 2.315 s ± 0.062 s [User: 1.950 s, System: 0.386 s] Range (min … max): 2.229 s … 2.397 s 10 runs Summary 'make -C Documentation -j1 lint-docs' in 'HEAD~0' ran 1.26 ± 0.04 times faster than 'make -C Documentation -j1 lint-docs' in 'HEAD~1' So let's use that pattern both for the "lint-docs" target, and a few miscellaneous other targets. This method of creating parent directories is explicitly racy in that we don't know if we're going to say always create a "foo" followed by a "foo/bar" under parallelism, or skip the "foo" because we created "foo/bar" first. In this case it doesn't matter for anything except that we aren't guaranteed to get the same number of rules firing when running make in parallel. 1. https://lore.kernel.org/git/211028.861r45y3pt.gmgdl@evledraar.gmail.com/ 2. https://lore.kernel.org/git/211028.86o879vvtp.gmgdl@evledraar.gmail.com/ 3. https://gitlab.com/avar/git-hyperfine/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-03 19:04:19 +03:00
### Templates
## mkdir_p_parent: lazily "mkdir -p" the path needed for a $@
## file. Uses $(wildcard) to avoid the "mkdir -p" if it's not
## needed.
##
## Is racy, but in a good way; we might redundantly (and safely)
## "mkdir -p" when running in parallel, but won't need to exhaustively create
## individual rules for "a" -> "prefix" -> "dir" -> "file" if given a
## "a/prefix/dir/file". This can instead be inserted at the start of
## the "a/prefix/dir/file" rule.
define mkdir_p_parent_template
$(if $(wildcard $(@D)),,$(QUIET_MKDIR_P_PARENT)$(shell mkdir -p $(@D)))
endef