From: Alex Gramiak <agrambot@gmail.com>
To: bug-gnulib@gnu.org
Subject: Add new macro gl_WARN_ADD_MULTIPLE
Date: Wed, 01 May 2019 17:00:24 -0600 [thread overview]
Message-ID: <87muk5n5kn.fsf@gmail.com> (raw)
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GNU Emacs spends about ~6s out of ~28s in its configuration process to
determine supported C compiler warnings. The attached patch introduces a
new macro, gl_WARN_ADD_MULTIPLE, that brings this down to about half a
second. This macro first checks if all the supplied warnings are
supported, and then only checks them individually (via gl_WARN_ADD) if
that check fails.
I have also attached sample files configure-prev.ac and configure-new.ac
that were extracted from Emacs's configure.ac for testing. I created a
new directory, copied m4/warnings.m4 and m4/manywarnings.m4 to a new m4
subdirectory, and ran:
autoconf -f <sample file>
then benchmarked using:
perf stat -r 20 ./configure
Results of configure-prev.ac:
Performance counter stats for './configure' (20 runs):
6,285.79 msec task-clock:u
0 context-switches:u
0 cpu-migrations:u
918,039 page-faults:u
11,101,658,357 cycles:u
12,777,542,067 stalled-cycles-frontend:u
11,234,412,307 stalled-cycles-backend:u
14,261,222,341 instructions:u
2,906,440,712 branches:u
100,574,333 branch-misses:u
6.34363 +- 0.00614 seconds time elapsed ( +- 0.10% )
Results of configure-new.ac:
Performance counter stats for './configure' (20 runs):
530.29 msec task-clock:u
0 context-switches:u
0 cpu-migrations:u
72,010 page-faults:u
901,496,456 cycles:u
1,066,313,480 stalled-cycles-frontend:u
949,724,068 stalled-cycles-backend:u
1,240,144,586 instructions:u
254,307,360 branches:u
7,217,416 branch-misses:u
0.53320 +- 0.00210 seconds time elapsed ( +- 0.39% )
Results of configure-new.ac with a forced fallback (I added a
nonexistent warning to ws):
Performance counter stats for './configure' (20 runs):
5,992.42 msec task-clock:u
0 context-switches:u
0 cpu-migrations:u
935,599 page-faults:u
11,197,607,809 cycles:u
12,982,878,617 stalled-cycles-frontend:u
11,427,814,210 stalled-cycles-backend:u
14,333,736,238 instructions:u
2,918,880,583 branches:u
100,570,882 branch-misses:u
6.0497 +- 0.0468 seconds time elapsed ( +- 0.77% )
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From ec89f6d04a6b5ac67ec787d28943e4fa4188e5f4 Mon Sep 17 00:00:00 2001
From: Alexander Gramiak <agrambot@gmail.com>
Date: Wed, 1 May 2019 16:31:23 -0600
Subject: [PATCH] warnings: Add new macro gl_WARN_ADD_MULTIPLE
* m4/warnings.m4 (gl_WARN_ADD_MULTIPLE): New macro.
---
ChangeLog | 5 +++++
m4/warnings.m4 | 46 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index cf4116bf3..324112055 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-05-01 Alexander Gramiak <agrambot@gmail.com>
+
+ warnings: Add new macro gl_WARN_ADD_MULTIPLE
+ * m4/warnings.m4 (gl_WARN_ADD_MULTIPLE): New macro.
+
2019-04-30 Paul Eggert <eggert@cs.ucla.edu>
Sync lib/mktime-internal.h from glibc
diff --git a/m4/warnings.m4 b/m4/warnings.m4
index 235cac617..92939233d 100644
--- a/m4/warnings.m4
+++ b/m4/warnings.m4
@@ -49,6 +49,52 @@ AS_VAR_POPDEF([gl_Flags])dnl
AS_VAR_POPDEF([gl_Warn])dnl
])
+# gl_WARN_ADD_MULTIPLE(OPTIONS, [VARIABLE = WARN_CFLAGS/WARN_CXXFLAGS],
+# [PROGRAM = AC_LANG_PROGRAM()])
+# -----------------------------------------------------------------
+# Check if the compiler supports OPTIONS when compiling PROGRAM
+# First check if all OPTIONS are supported together, and if not,
+# check each option individually.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_WARN_ADD_MULTIPLE],
+[
+dnl FIXME: gl_Warn must be used unquoted until we can assume Autoconf
+dnl 2.64 or newer.
+AS_VAR_PUSHDEF([gl_Warn], [gl_cv_warn_[]_AC_LANG_ABBREV[]_$1])dnl
+AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl
+gl_positives=
+for gl_warn_item in $1; do
+ case $gl_warn_item in
+ -Wno-*) gl_positives="$gl_positives -W`expr "X$gl_warn_item" : 'X-Wno-\(.*\)'`" ;;
+ *) gl_positives="$gl_positives $gl_warn_item"
+ esac
+done
+m4_pushdef([gl_Positives], [$gl_positives])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], m4_defn([gl_Warn]), [
+ gl_save_compiler_FLAGS="$gl_Flags"
+ gl_AS_VAR_APPEND(m4_defn([gl_Flags]),
+ [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positives])["])
+ AC_LINK_IFELSE([m4_default([$3], [AC_LANG_PROGRAM([])])],
+ [AS_VAR_SET(gl_Warn, [yes])],
+ [AS_VAR_SET(gl_Warn, [no])])
+ gl_Flags="$gl_save_compiler_FLAGS"
+])
+AS_VAR_IF(gl_Warn,
+ [yes],
+ [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_]_AC_LANG_PREFIX[FLAGS]], [[$2]]),
+ [" $1"])],
+ [for gl_warn_item in $1; do
+ gl_WARN_ADD([$gl_warn_item])
+ done])
+m4_popdef([gl_Positives])dnl
+AS_VAR_POPDEF([gl_Flags])dnl
+AS_VAR_POPDEF([gl_Warn])dnl
+m4_ifval([$2],
+ [AS_LITERAL_IF([$2], [AC_SUBST([$2])])],
+ [AC_SUBST([WARN_]_AC_LANG_PREFIX[FLAGS])])dnl
+])
+
# gl_UNKNOWN_WARNINGS_ARE_ERRORS
# ------------------------------
# Clang doesn't complain about unknown warning options unless one also
--
2.21.0
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AC_INIT(GNU Emacs, 27.0.50, bug-gnu-emacs@gnu.org, , https://www.gnu.org/software/emacs/)
# This, $nw, is the list of warnings we disable.
nw=
nw="$nw -Wcast-align -Wcast-align=strict" # Emacs is tricky with pointers.
nw="$nw -Wduplicated-branches" # Too many false alarms
nw="$nw -Wformat-overflow=2" # False alarms due to GCC bug 80776
nw="$nw -Wsystem-headers" # Don't let system headers trigger warnings
nw="$nw -Woverlength-strings" # Not a problem these days
nw="$nw -Wformat-nonliteral" # we do this a lot
nw="$nw -Wvla" # Emacs uses <vla.h>.
nw="$nw -Wunused-const-variable=2" # lisp.h declares const objects.
nw="$nw -Winline" # OK to ignore 'inline'
nw="$nw -Wstrict-overflow" # OK to optimize assuming that
# signed overflow has undefined behavior
nw="$nw -Wsync-nand" # irrelevant here, and provokes ObjC warning
nw="$nw -Wunsafe-loop-optimizations" # OK to suppress unsafe optimizations
nw="$nw -Wbad-function-cast" # These casts are no worse than others.
nw="$nw -Wabi" # Not useful, perceived as noise
# Emacs doesn't care about shadowing; see
# <https://lists.gnu.org/r/emacs-diffs/2011-11/msg00265.html>.
nw="$nw -Wshadow"
# Emacs's use of alloca inhibits protecting the stack.
nw="$nw -Wstack-protector"
# Emacs's use of __attribute__ ((cold)) causes false alarms with this option.
nw="$nw -Wsuggest-attribute=cold"
# Emacs's use of partly-const functions such as Fgnutls_available_p
# make this option problematic.
nw="$nw -Wsuggest-attribute=const"
# Emacs's use of partly-pure functions such as CHECK_TYPE make this
# option problematic.
nw="$nw -Wsuggest-attribute=pure"
# This part is merely for shortening the command line,
# since -Wall implies -Wswitch.
nw="$nw -Wswitch"
# This part is merely for shortening the command line,
# since -Wno-FOO needs to be added below regardless.
nw="$nw -Wmissing-field-initializers"
nw="$nw -Woverride-init"
nw="$nw -Wtype-limits"
nw="$nw -Wunused-parameter"
gl_MANYWARN_ALL_GCC([ws])
gl_MANYWARN_COMPLEMENT([ws], [$ws], [$nw])
for w in $ws; do
gl_WARN_ADD([$w])
done
gl_WARN_ADD([-Wredundant-decls]) # Prefer this, as we don't use Bison.
gl_WARN_ADD([-Wno-missing-field-initializers]) # We need this one
gl_WARN_ADD([-Wno-override-init]) # More trouble than it is worth
gl_WARN_ADD([-Wno-sign-compare]) # Too many warnings for now
gl_WARN_ADD([-Wno-type-limits]) # Too many warnings for now
gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now
gl_WARN_ADD([-Wno-format-nonliteral])
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AC_INIT(GNU Emacs, 27.0.50, bug-gnu-emacs@gnu.org, , https://www.gnu.org/software/emacs/)
# This, $nw, is the list of warnings we disable.
nw=
nw="$nw -Wcast-align -Wcast-align=strict" # Emacs is tricky with pointers.
nw="$nw -Wduplicated-branches" # Too many false alarms
nw="$nw -Wformat-overflow=2" # False alarms due to GCC bug 80776
nw="$nw -Wsystem-headers" # Don't let system headers trigger warnings
nw="$nw -Woverlength-strings" # Not a problem these days
nw="$nw -Wformat-nonliteral" # we do this a lot
nw="$nw -Wvla" # Emacs uses <vla.h>.
nw="$nw -Wunused-const-variable=2" # lisp.h declares const objects.
nw="$nw -Winline" # OK to ignore 'inline'
nw="$nw -Wstrict-overflow" # OK to optimize assuming that
# signed overflow has undefined behavior
nw="$nw -Wsync-nand" # irrelevant here, and provokes ObjC warning
nw="$nw -Wunsafe-loop-optimizations" # OK to suppress unsafe optimizations
nw="$nw -Wbad-function-cast" # These casts are no worse than others.
nw="$nw -Wabi" # Not useful, perceived as noise
# Emacs doesn't care about shadowing; see
# <https://lists.gnu.org/r/emacs-diffs/2011-11/msg00265.html>.
nw="$nw -Wshadow"
# Emacs's use of alloca inhibits protecting the stack.
nw="$nw -Wstack-protector"
# Emacs's use of __attribute__ ((cold)) causes false alarms with this option.
nw="$nw -Wsuggest-attribute=cold"
# Emacs's use of partly-const functions such as Fgnutls_available_p
# make this option problematic.
nw="$nw -Wsuggest-attribute=const"
# Emacs's use of partly-pure functions such as CHECK_TYPE make this
# option problematic.
nw="$nw -Wsuggest-attribute=pure"
# This part is merely for shortening the command line,
# since -Wall implies -Wswitch.
nw="$nw -Wswitch"
# This part is merely for shortening the command line,
# since -Wno-FOO needs to be added below regardless.
nw="$nw -Wmissing-field-initializers"
nw="$nw -Woverride-init"
nw="$nw -Wtype-limits"
nw="$nw -Wunused-parameter"
gl_MANYWARN_ALL_GCC([ws])
gl_MANYWARN_COMPLEMENT([ws], [$ws], [$nw])
ws="$ws -Wredundant-decls" # Prefer this, as we don't use Bison.
ws="$ws -Wno-missing-field-initializers" # We need this one
ws="$ws -Wno-override-init" # More trouble than it is worth
ws="$ws -Wno-sign-compare" # Too many warnings for now
ws="$ws -Wno-type-limits" # Too many warnings for now
ws="$ws -Wno-unused-parameter" # Too many warnings for now
ws="$ws -Wno-format-nonliteral"
dnl ws="$ws -Wbogus-warning"
gl_WARN_ADD_MULTIPLE([$ws])
next reply other threads:[~2019-05-01 23:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 23:00 Alex Gramiak [this message]
2019-05-02 8:16 ` Add new macro gl_WARN_ADD_MULTIPLE Bruno Haible
2019-05-02 8:48 ` Tim Rühsen
2019-05-02 11:28 ` Bruno Haible
2019-05-02 17:39 ` Tim Rühsen
2019-05-02 19:12 ` Bruno Haible
2019-05-02 19:38 ` Tim Rühsen
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