Re: [PATCH -v2] scipts/tags.sh: Add custom sort order

From: Masahiro Yamada
Date: Wed Sep 02 2020 - 11:59:20 EST

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On Fri, Aug 7, 2020 at 2:28 AM <peterz@xxxxxxxxxxxxx> wrote:
>
>
> One long standing annoyance I have with using vim-tags is that our tags
> file is not properly sorted. That is, the sorting exhuberant Ctags does
> is only on the tag itself.
>
> The problem with that is that, for example, the tag 'mutex' appears a
> mere 505 times, 492 of those are structure members. However it is _far_
> more likely that someone wants the struct definition when looking for
> the mutex tag than any of those members. However, due to the nature of
> the sorting, the struct definition will not be first.
>
> So add a script that does a custom sort of the tags file, taking the tag
> kind into account.
>
> The kind ordering is roughly: 'type', 'function', 'macro', 'enum', rest.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
> Changes since v1:
> - removed the need for tags.unsorted by using a pipe
>
> Due to this change 'make tags' is now actually faster than it was before
> due to less sorting.
>
> scripts/sort-tags.awk | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++
> scripts/tags.sh | 11 +++++--
> 2 files changed, 87 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/sort-tags.awk b/scripts/sort-tags.awk
> new file mode 100755
> index 000000000000..1eb50406c9d3
> --- /dev/null
> +++ b/scripts/sort-tags.awk
> @@ -0,0 +1,79 @@
> +#!/usr/bin/awk -f
> +
> +# $ ctags --list-kinds
> +# C
> +# c classes
> +# s structure names
> +# t typedefs
> +# g enumeration names
> +# u union names
> +# n namespaces
> +
> +# f function definitions
> +# p function prototypes [off]
> +# d macro definitions
> +
> +# e enumerators (values inside an enumeration)
> +# m class, struct, and union members
> +# v variable definitions
> +
> +# l local variables [off]
> +# x external and forward variable declarations [off]
> +
> +BEGIN {
> + FS = "\t"
> +
> + sort = "LC_ALL=C sort"
> +
> + # our sort order for C kinds:
> + order["c"] = "A"
> + order["s"] = "B"
> + order["t"] = "C"
> + order["g"] = "D"
> + order["u"] = "E"
> + order["n"] = "F"
> + order["f"] = "G"
> + order["p"] = "H"
> + order["d"] = "I"
> + order["e"] = "J"
> + order["m"] = "K"
> + order["v"] = "L"
> + order["l"] = "M"
> + order["x"] = "N"
> +}
> +
> +# pass through header
> +/^!_TAG/ {
> + print $0
> + next
> +}
> +
> +{
> + # find 'kinds'
> + for (i = 1; i <= NF; i++) {
> + if ($i ~ /;"$/) {
> + kind = $(i+1)
> + break;
> + }
> + }
> +
> + # create sort key
> + if (order[kind])
> + key = $1 order[kind];
> + else
> + key = $1 "Z";
> +
> + # get it sorted
> + print key "\t" $0 |& sort
> +}
> +
> +END {
> + close(sort, "to")
> + while ((sort |& getline) > 0) {
> + # strip key
> + sub(/[^[:space:]]*[[:space:]]*/, "")
> + print $0
> + }
> + close(sort)
> +}
> +
> diff --git a/scripts/tags.sh b/scripts/tags.sh
> index 4e18ae5282a6..51087c3d8b1e 100755
> --- a/scripts/tags.sh
> +++ b/scripts/tags.sh
> @@ -251,8 +251,10 @@ setup_regex()
>
> exuberant()
> {
> + (
> +
> setup_regex exuberant asm c
> - all_target_sources | xargs $1 -a \
> + all_target_sources | xargs $1 \
> -I __initdata,__exitdata,__initconst,__ro_after_init \
> -I __initdata_memblock \
> -I __refdata,__attribute,__maybe_unused,__always_unused \
> @@ -266,12 +268,15 @@ exuberant()
> -I DEFINE_TRACE,EXPORT_TRACEPOINT_SYMBOL,EXPORT_TRACEPOINT_SYMBOL_GPL \
> -I static,const \
> --extra=+fq --c-kinds=+px --fields=+iaS --langmap=c:+.h \
> + --sort=no -o - \
> "${regex[@]}"
>
> setup_regex exuberant kconfig
> - all_kconfigs | xargs $1 -a \
> - --langdef=kconfig --language-force=kconfig "${regex[@]}"
> + all_kconfigs | xargs $1 \
> + --langdef=kconfig --language-force=kconfig --sort=no \
> + -o - "${regex[@]}"
>
> + ) | scripts/sort-tags.awk > tags
> }
>
> emacs()

Sorry for the long delay.

First, this patch breaks 'make TAGS'
if 'etags' is a symlink to exuberant ctags.

masahiro@oscar:~/ref/linux$ etags --version
Exuberant Ctags 5.9~svn20110310, Copyright (C) 1996-2009 Darren Hiebert
Addresses: <dhiebert@xxxxxxxxxxxxxxxxxxxxx>, http://ctags.sourceforge.net
Optional compiled features: +wildcards, +regex

masahiro@oscar:~/ref/linux$ make TAGS
GEN TAGS
etags: Warning: include/linux/seqlock.h:738: null expansion of name pattern "\2"
sed: can't read TAGS: No such file or directory
make: *** [Makefile:1820: TAGS] Error 2

The reason is the hard-coded ' > tags',
and easy to fix.

But, honestly, I am not super happy about this patch.

Reason 1
In my understanding, sorting by the tag kind only works
for ctags. My favorite editor is emacs.
(Do not get me wrong. I do not intend emacs vs vi war).
So, I rather do 'make TAGS' instead of 'make tags',
but this solution would not work for etags because
etags has a different format.
So, I'd rather want to see a more general solution.

Reason 2
We would have more messy code, mixing two files/languages

When is it useful to tag structure members?

If they are really annoying, why don't we delete them
instead of moving them to the bottom of the tag file?

I attached an alternative solution,
and wrote up my thoughts in the log.

What do you think?

--
Best Regards
Masahiro Yamada
From 1a003fce7e4f8460ef3256fb5d958fb5c6cc631e Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Date: Wed, 2 Sep 2020 21:49:59 +0900
Subject: [PATCH] scripts/tags.sh: remove m, v, x tag kinds from exuberant tags

Exuberant Ctags supports the following kinds of tags:

$ ctags --list-kinds=c
c classes
d macro definitions
e enumerators (values inside an enumeration)
f function definitions
g enumeration names
l local variables [off]
m class, struct, and union members
n namespaces
p function prototypes [off]
s structure names
t typedefs
u union names
v variable definitions
x external and forward variable declarations [off]

This commit excludes 'm', 'v', and 'x'.

Peter Zijlstra states:
"The problem with that is that, for example, the tag 'mutex' appears a
mere 505 times, 492 of those are structure members. However it is _far_
more likely that someone wants the struct definition when looking for
the mutex tag than any of those members."
(https://lkml.org/lkml/2020/8/6/512";)

So, 'm' is rather annoying than useful. For the same reason, it seems
better to turn off 'v'.

You may argue about the criteria, but we need to draw a line somewhere
to make it reasonable for the majority of people.

We flipped 'p' and 'x' in the past:

[1] commit f6333eb4e788 ("kbuild: Add ctags support for function
prototypes and external variable declarations") added 'p' and 'x',
but did not explain when they are actually useful.

[2] commit 7db86dc97fb0 ("ctags: usability fix") removed 'p' and 'x',
stating both of them make no real sense.

[3] commit 0a18a9386c05 ("tags: put function prototypes back!")
re-added 'p' and 'x', but the commit log only mentioned 'p'.

OK, [3] clearly explained why 'p' is useful, but turned --c-kinds=+px
into --c-kinds=-px. So, 'x' was also (accidentally?) disabled. I think
it should have been --c-kinds=+p-x, or more simply --c-kinds=+p since
'x' is off by default.

It seems a bug of [3], so I disabled 'x' to get back the pre-[3]
behavior.

'make tags' and 'make TAGS' will run faster, create much smaller tags
if Ctags is exuberant.

Reviewed-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/tags.sh | 15 +--------------
1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index 32d3f53af10b..440f4ecad43b 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -179,19 +179,6 @@ regex_c=(
'/^DEF_PCI_AC_$\|NO$RET($[[:alnum:]_]*$.*/\2/'
'/^PCI_OP_READ($\w*$.*[1-4])/pci_bus_read_config_\1/'
'/^PCI_OP_WRITE($\w*$.*[1-4])/pci_bus_write_config_\1/'
- '/\<DEFINE_$RT_MUTEX\|MUTEX\|SEMAPHORE\|SPINLOCK$($[[:alnum:]_]*$/\2/v/'
- '/\<DEFINE_$RAW_SPINLOCK\|RWLOCK\|SEQLOCK$($[[:alnum:]_]*$/\2/v/'
- '/\<DECLARE_$RWSEM\|COMPLETION$($[[:alnum:]_]\+$/\2/v/'
- '/\<DECLARE_BITMAP($[[:alnum:]_]*$/\1/v/'
- '/$^\|\s$$\|L\|H$LIST_HEAD($[[:alnum:]_]*$/\3/v/'
- '/$^\|\s$RADIX_TREE($[[:alnum:]_]*$/\2/v/'
- '/\<DEFINE_PER_CPU([^,]*, *$[[:alnum:]_]*$/\1/v/'
- '/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *$[[:alnum:]_]*$/\1/v/'
- '/\<DECLARE_WAIT_QUEUE_HEAD($[[:alnum:]_]*$/\1/v/'
- '/\<DECLARE_$TASKLET\|WORK\|DELAYED_WORK$($[[:alnum:]_]*$/\2/v/'
- '/$^\s$OFFSET($[[:alnum:]_]*$/\2/v/'
- '/$^\s$DEFINE($[[:alnum:]_]*$/\2/v/'
- '/\<$DEFINE\|DECLARE$_HASHTABLE($[[:alnum:]_]*$/\2/v/'
'/\<DEFINE_ID$R\|A$($[[:alnum:]_]\+$/\2/'
'/\<DEFINE_WD_CLASS($[[:alnum:]_]\+$/\1/'
'/\<ATOMIC_NOTIFIER_HEAD($[[:alnum:]_]\+$/\1/'
@@ -255,7 +242,7 @@ exuberant()
-I EXPORT_SYMBOL,EXPORT_SYMBOL_GPL,ACPI_EXPORT_SYMBOL \
-I DEFINE_TRACE,EXPORT_TRACEPOINT_SYMBOL,EXPORT_TRACEPOINT_SYMBOL_GPL \
-I static,const \
- --extra=+fq --c-kinds=+px --fields=+iaS --langmap=c:+.h \
+ --extra=+fq --c-kinds=+p-mv --fields=+iaS --langmap=c:+.h \
"${regex[@]}"

setup_regex exuberant kconfig
--
2.25.1

Next message: Joerg Roedel: "[PATCH] x86/mm/32: Bring back vmalloc faulting on x86_32"
Previous message: David Laight: "RE: [PATCH v2] x86/asm: Replace __force_order with memory clobber"
Next in thread: Masahiro Yamada: "Re: [PATCH -v2] scipts/tags.sh: Add custom sort order"
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