On Tue, Apr 05 2022, Adam Dinwoodie wrote: > On Thu, Mar 03, 2022 at 05:04:16PM +0100, Ævar Arnfjörð Bjarmason wrote: >> 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@xxxxxxxxxxxxxxxxxxx/ >> >> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> >> --- >> Makefile | 2 -- >> shared.mak | 5 +++++ >> 2 files changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/Makefile b/Makefile >> index 1ac924bd844..ce362720947 100644 >> --- a/Makefile >> +++ b/Makefile >> @@ -2580,8 +2580,6 @@ ASM_SRC := $(wildcard $(OBJECTS:o=S)) >> ASM_OBJ := $(ASM_SRC:S=o) >> C_OBJ := $(filter-out $(ASM_OBJ),$(OBJECTS)) >> >> -.SUFFIXES: >> - >> $(C_OBJ): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) >> $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< >> $(ASM_OBJ): %.o: %.S GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) >> diff --git a/shared.mak b/shared.mak >> index 29f0e69ecb9..1dda948df09 100644 >> --- a/shared.mak >> +++ b/shared.mak >> @@ -9,6 +9,11 @@ >> %:: s.% >> %:: SCCS/s.% >> >> +## Likewise delete default $(SUFFIXES). See: >> +## >> +## info make --index-search=.SUFFIXES >> +.SUFFIXES: >> + >> ### Flags affecting all rules >> >> # A GNU make extension since gmake 3.72 (released in late 1994) to > > I confess I really don't understand why, but as part of testing > v2.36.0-rc0 on Cygwin, I've started getting errors building the info > pages, and bisect points to this commit as the culprit. > > Specifically, I've been running > > git clean -dffx && make configure && ./configure && make -j4 info > > Without this commit, that gets me a successful build; there's a bunch of > noisy warnings that have been hanging around for a long time, and I think > are fundamentally due to the slightly mismatched documentation libraries > that Cygwin has. With this commit, I get the same noisy warnings, but I > also get the error "could not open .texi: No such file or directory". > > I have to confess, I don't really understand this aspect of GNU Make, so > I'm not sure if this is a problem with Cygwin having a bad toolset or > there being something about my environment that means this doesn't work, > but regardless, it's currently causing the Cygwin Git builds to fail. Hi. I can reproduce this locally, will look at it and fix it, sorry.
