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Makefile improvements #4024

Merged
merged 3 commits into from
Mar 1, 2021
Merged

Makefile improvements #4024

merged 3 commits into from
Mar 1, 2021

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kmk3
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@kmk3 kmk3 commented Mar 1, 2021 

$ git log --reverse --pretty='* %s' master..
* makefiles: fix whitespace
* makefiles: fix misc blank line consistency
* makefiles: make all, clean and distclean PHONY

Some minor cleanup and improvements before adding new stuff.

@Fred-Barclay From the amount of whitespace-fixing commits, I think you'll like
the commands from commit 0043776 ("makefiles: fix whitespace"):

$ git ls-files -z -- '*Makefile*' |
  xargs -0 -I '{}' sh -c \
  "test -s '{}' && printf '%s\n' \"\`git stripspace <'{}'\`\" >'{}'"

I don't know if you've used something like that before, but to me it has been
very handy on many occasions. From git-stripspace(1):

Read text, such as commit messages, notes, tags and branch descriptions, from
the standard input and clean it in the manner used by Git.

With no arguments, this will:

  • remove trailing whitespace from all lines

  • collapse multiple consecutive empty lines into one empty line

  • remove empty lines from the beginning and end of the input

  • add a missing \n to the last line if necessary.

In the case where the input consists entirely of whitespace characters, no
output will be produced.

NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix
mode of git-apply(1) for correcting whitespace of patches or files in the
repository.

Though if there any plans to do a mass cleaning, it would be nice to have
something like that on a pre-commit hook/ci check beforehand, to catch errors
before they go to master and thus avoid the need for periodic clean-ups.

kmk3 added 3 commits March 1, 2021 16:04
@kmk3
makefiles: fix whitespace
0043776 
With a fun little script:

    $ git ls-files -z -- '*Makefile*' |
      xargs -0 -I '{}' sh -c \
      "test -s '{}' && printf '%s\n' \"\`git stripspace <'{}'\`\" >'{}'"
@kmk3
makefiles: fix misc blank line consistency
7e3888c
@kmk3
makefiles: make all, clean and distclean PHONY
2465f92 
Avoid a stat() call for each affected target and also potentially speed
up parallel builds.

From the GNU make manual[1]:

> Phony targets are also useful in conjunction with recursive
> invocations of make (see Recursive Use of make).  In this situation
> the makefile will often contain a variable which lists a number of
> sub-directories to be built.

[...]

> The implicit rule search (see Implicit Rules) is skipped for .PHONY
> targets.  This is why declaring a target as .PHONY is good for
> performance, even if you are not worried about the actual file
> existing.

Commands used to search, replace and cleanup:

    $ find -type f -name '*Makefile.in' -exec sed -i.bak \
      -e 's/^all:/.PHONY: all\nall:/' \
      -e 's/^clean:/.PHONY: clean\nclean:/' \
      -e 's/^distclean:/.PHONY: distclean\ndistclean:/' '{}' +
    $ find -type f -name '*Makefile.in.bak' -exec rm '{}' +

[1]: https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html
@kmk3 kmk3 changed the title Improve makefiles Makefile improvements Mar 1, 2021
@reinerh reinerh merged commit 22fd89b into netblue30:master Mar 1, 2021
@kmk3 kmk3 deleted the improve-makefiles branch March 1, 2021 20:59
kmk3 added a commit to kmk3/firejail that referenced this pull request Mar 24, 2021
@kmk3
makefiles: replace character class with plain char
7c2ef65 
When using the "wildcard" internal functions.

This usage has been present since the first "real" commit in the
repository: commit 1379851 ("Baseline firejail 0.9.28").

>     H_FILE_LIST       = $(sort $(wildcard *.[h]))
>     C_FILE_LIST       = $(sort $(wildcard *.c))

There is only a single character (i.e.: "h") inside the character class,
so its usage should make no functional difference.  It may stem from a
construct that could have originally looked something like this:

    C_FILE_LIST       = $(sort $(wildcard *.[ch]))

Which would match both the implementation files and the headers.

From Section 4.4, [Using Wildcard Characters in File Names][1] of the
GNU make manual:

> A single file name can specify many files using wildcard characters.
> The wildcard characters in make are ‘*’, ‘?’ and ‘[…]’, the same as in
> the Bourne shell.  For example, *.c specifies a list of all the files
> (in the working directory) whose names end in ‘.c’.

See also Section 2.13, [Pattern Matching Notation][2] of POSIX.1-2017.

Commands used to search, replace and clean up:

    $ find . -name .git -prune -o -type f \
      \( -name Makefile -o -name Makefile.in \
      -o -name '*.mk' -o -name '*.mk.in' \) -print0 |
      xargs -0 grep -Fl '$(wildcard *.[h])' | tr '\n' '\000' |
      xargs -0 sed -i.bak -e \
      's/\$(wildcard \*.\[h\])/$(wildcard *.h)/'

    $ find . -name .git -prune -o -type f \
      -name '*.bak' -exec rm '{}' +

Note: To make sure that this doesn't actually change anything
functionally, I built firejail-git (AUR) on Artix from master and from
this commit and diffing the resulting files produced no output (other
than showing changes related to the build timestamps).

Misc: Reference to the previous makefile-related changes: commit
2465f92 ("makefiles: make all, clean and distclean PHONY") /
netblue30#4024

[1]: https://www.gnu.org/software/make/manual/html_node/Wildcards.html
[2]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
@kmk3 kmk3 mentioned this pull request Mar 24, 2021
Merged
@kmk3 kmk3 mentioned this pull request Sep 24, 2021
Merged
kmk3 added a commit to kmk3/firejail that referenced this pull request Feb 3, 2023
@kmk3
build: mark most phony targets as such
f48886f 
To improve clarity and to prevent unnecessary filesystem lookups.

Overall, this appears to reduce the amount of implicit rule searches by
~4% for the default build and by ~12% for the "man" target (as an
example):

    $ git checkout master >/dev/null 2>&1
    $ git show --pretty='%h %ai %s' -s
    b55cb6a 2023-01-31 18:56:42 -0500 testing
    $ ./configure >/dev/null
    $ make clean >/dev/null && make --debug=i -j 4     | grep -F 'Trying implicit' | wc -l
    7101
    $ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l
    1239
    # (with this commit applied)
    $ make clean >/dev/null && make --debug=i -j 4     | grep -F 'Trying implicit' | wc -l
    6793
    $ make clean >/dev/null && make --debug=i -j 4 man | grep -F 'Trying implicit' | wc -l
    1085

Environment: GNU make 4.4-1 on Artix Linux.

Note: The amount lines printed is the same on non-parallel builds (that
is, without `-j 4`).

See commit 2465f92 ("makefiles: make all, clean and distclean PHONY",
2021-02-12) / PR netblue30#4024 for details.

Note: By "most phony targets" I mean all non-path targets except for the
testing targets, which were being changed recently (for example, the
"test-github" target) and so might still be under development.
@kmk3 kmk3 mentioned this pull request Feb 3, 2023
Merged
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2 participants
@kmk3 @reinerh