build: disable all built-in implicit make rules #5864
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To make the makefiles look more similar.
Clear `.SUFFIXES:` to reduce unnecessary filesystem lookups.
Overall, this appears to reduce the amount of implicit rule searches by
~62% for the default build and by ~96% for the "man" target (as an
example):
$ git checkout master >/dev/null 2>&1
$ git show --pretty='%h %ai %s' -s
a8f01a3 2023-06-20 05:26:23 +0000 Merge pull request netblue30#5859 from kmk3/build-remove-retpoline
$ ./configure >/dev/null
$ make clean >/dev/null && make --debug=i -j 4 | grep -F 'Trying implicit' | wc -l
6798
$ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l
1085
# (with this commit applied)
$ make clean >/dev/null && make --debug=i -j 4 | grep -F 'Trying implicit' | wc -l
2535
$ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l
42
Environment: GNU make 4.4.1-2 on Artix Linux.
Commands used to search and replace:
$ git ls-files -z -- '*Makefile*' | xargs -0 -I '{}' sh -c \
"printf '%s\n' \"\$(sed '1s/^/.SUFFIXES:\n/' '{}')\" >'{}'"
See also commit f48886f ("build: mark most phony targets as such",
2023-02-01) / PR netblue30#5637.
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Use `make -r` to reduce unnecessary filesystem lookups. Overall, this appears to reduce the amount of implicit rule searches by ~93.3% (~97.5% compared to a8f01a3) for the default build and by ~83.3% (~99.3% compared to a8f01a3) for the "man" target (as an example): $ git show --pretty='%h %ai %s' -s a8f01a3 2023-06-20 05:26:23 +0000 Merge pull request netblue30#5859 from kmk3/build-remove-retpoline $ ./configure >/dev/null $ make clean >/dev/null && make --debug=i -j 4 | grep -F 'Trying implicit' | wc -l 6798 $ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l 1085 # (in the previous commit) $ make clean >/dev/null && make --debug=i -j 4 | grep -F 'Trying implicit' | wc -l 2535 $ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l 42 # (with this commit applied) $ make clean >/dev/null && make --debug=i -j 4 | grep -F 'Trying implicit' | wc -l 170 $ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l 7 Environment: GNU make 4.4.1-2 on Artix Linux. Note: According to make(1p) in POSIX.1-2017, "If .SUFFIXES does not have any prerequisites, the list of known suffixes shall be cleared.", while "The result of setting MAKEFLAGS in the Makefile is unspecified." Commands used to search and replace: $ git ls-files -z -- '*Makefile*' | xargs -0 -I '{}' sh -c \ "printf '%s\n' \"\$(sed -E \ 's/^(.SUFFIXES:)/\1\nMAKEFLAGS += -r\n/' '{}')\" >'{}'"
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To reduce unnecessary filesystem lookups.
Overall, this appears to reduce the amount of implicit rule searches by ~97.5%
for the default build and by ~99.3% for the "man" target (as an example):
Environment: GNU make 4.4.1-2 on Artix Linux.
Note: According to make(1p) in POSIX.1-2017, "If .SUFFIXES does not have
any prerequisites, the list of known suffixes shall be cleared.", while
"The result of setting MAKEFLAGS in the Makefile is unspecified."
See also commit f48886f ("build: mark most phony targets as such",
2023-02-01) / PR #5637.