From df087711cf7be55268a55e7820f4d928cb34c078 Mon Sep 17 00:00:00 2001
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From: "Yann E. MORIN" <yann.morin.1998@free.fr>
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Date: Sat, 9 Jul 2016 20:44:36 +0200
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Subject: [PATCH] m4: fix detection of atomics
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In cross-compilation, it is impossible to run code at configure time to
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detect the target specifics.
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As such, AC_TRY_RUN fails miserably to detect reliably that atomic
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intrisics are present in a toolchain, and decides they are not just
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because this is cross-compilation.
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Instead of AC_TRY_RUN, use AC_LINK_IFELSE that does not need to actually
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run code, since all we're interested in is whether the intrisics are
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present (or not). Fix both the 32- and 64-bit variants, even if the
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latter is not used currently.
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Fixes build failures detected by the Buildroot autobuilders, like:
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http://autobuild.buildroot.org/results/23a/23ac0e742ed3a70ae4d038f8c9eadc23e708f671/build-end.log
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http://autobuild.buildroot.org/results/192/1923d0b570adba494f83747a9610ea6ec35f5223/build-end.log
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and many other cases, espcially on architectures where such intrisics are
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present, but where the toolchain does not have threads (and anyway, it
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is much more efficient to use the intrisics rather than use mutexes).
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Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
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---
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Patch sent upstream:
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https://github.com/rsyslog/libfastjson/pull/109
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---
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m4/atomic_operations.m4 | 6 ++----
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m4/atomic_operations_64bit.m4 | 6 ++----
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2 files changed, 4 insertions(+), 8 deletions(-)
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diff --git a/m4/atomic_operations.m4 b/m4/atomic_operations.m4
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index ad0ee60..7d2bca6 100644
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--- a/m4/atomic_operations.m4
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+++ b/m4/atomic_operations.m4
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@@ -9,9 +9,7 @@
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#
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AC_DEFUN([RS_ATOMIC_OPERATIONS],
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[AC_CACHE_CHECK([whether the compiler provides atomic builtins], [ap_cv_atomic_builtins],
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-[AC_TRY_RUN([
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-int main()
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-{
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+[AC_LINK_IFELSE([AC_LANG_PROGRAM([], [[
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unsigned long val = 1010, tmp, *mem = &val;
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if (__sync_fetch_and_add(&val, 1010) != 1010 || val != 2020)
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@@ -44,7 +42,7 @@ int main()
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return 1;
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return 0;
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-}], [ap_cv_atomic_builtins=yes], [ap_cv_atomic_builtins=no], [ap_cv_atomic_builtins=no])])
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+]])], [ap_cv_atomic_builtins=yes], [ap_cv_atomic_builtins=no])])
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if test "$ap_cv_atomic_builtins" = "yes"; then
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AC_DEFINE(HAVE_ATOMIC_BUILTINS, 1, [Define if compiler provides atomic builtins])
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diff --git a/m4/atomic_operations_64bit.m4 b/m4/atomic_operations_64bit.m4
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index 9fbef0a..d01a977 100644
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--- a/m4/atomic_operations_64bit.m4
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+++ b/m4/atomic_operations_64bit.m4
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@@ -9,9 +9,7 @@
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#
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AC_DEFUN([RS_ATOMIC_OPERATIONS_64BIT],
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[AC_CACHE_CHECK([whether the compiler provides atomic builtins for 64 bit data types], [ap_cv_atomic_builtins_64],
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-[AC_TRY_RUN([
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-int main()
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-{
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+[AC_LINK_IFELSE([AC_LANG_PROGRAM([], [[
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unsigned long long val = 1010, tmp, *mem = &val;
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if (__sync_fetch_and_add(&val, 1010) != 1010 || val != 2020)
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@@ -44,7 +42,7 @@ int main()
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return 1;
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return 0;
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-}], [ap_cv_atomic_builtins_64=yes], [ap_cv_atomic_builtins_64=no], [ap_cv_atomic_builtins_64=no])])
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+]])], [ap_cv_atomic_builtins_64=yes], [ap_cv_atomic_builtins_64=no])])
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if test "$ap_cv_atomic_builtins_64" = "yes"; then
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AC_DEFINE(HAVE_ATOMIC_BUILTINS64, 1, [Define if compiler provides 64 bit atomic builtins])
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--
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2.7.4
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