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>

diff --git a/Makefile b/Makefile
index 1ac924bd84486ef5274c02556ced36bbe071fd59..ce3627209479c946341649cc129d0b6db568584b 100644 (file)
--- 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 29f0e69ecb9b474e01dd3fefc753e224a18db676..1dda948df09c8cd924c6a47ea96ca5626b2a3a5c 100644 (file)
--- 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