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.
