From 7375b0b58c4e81a42b33ed97fd96a1002ef1c752 Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Tue, 1 Oct 2019 21:07:07 -0400
Subject: [PATCH 1/3] Add libatomic for 32-bit ARM

Fixes #3113

(cherry picked from commit 74b4737d8f0e1922ef5314a158271acf81cd79f8)
---
 configure.ac | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/configure.ac b/configure.ac
index e417ebadf..ff6866c3e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -157,6 +157,11 @@ AX_BOOST_BASE([1.66], [CXXFLAGS="$BOOST_CPPFLAGS $CXXFLAGS"], [AC_MSG_ERROR([Nix
 # ends up with LDFLAGS being empty, so we set it afterwards.
 LDFLAGS="$BOOST_LDFLAGS $LDFLAGS"
 
+# Boost atomic needs GCC libatomic on 32-bit ARM
+case "$host_cpu" in
+  armv5*|armv6*|armv7*) LIBS="-latomic $LIBS"
+esac
+
 
 PKG_PROG_PKG_CONFIG
 

From f1688f213640fe3b3d4252d61dbd7ad61a7a119c Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Tue, 1 Oct 2019 21:22:18 -0400
Subject: [PATCH 2/3] Use more robust test for libatomics

Taken from Mesa configure script:

https://github.com/mesa3d/mesa/blob/17.2/configure.ac#L405-L427
(cherry picked from commit b1c34152feac76c9baded58732068541b7a586f1)
---
 configure.ac | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index ff6866c3e..8e3e0e5ce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -157,11 +157,18 @@ AX_BOOST_BASE([1.66], [CXXFLAGS="$BOOST_CPPFLAGS $CXXFLAGS"], [AC_MSG_ERROR([Nix
 # ends up with LDFLAGS being empty, so we set it afterwards.
 LDFLAGS="$BOOST_LDFLAGS $LDFLAGS"
 
-# Boost atomic needs GCC libatomic on 32-bit ARM
-case "$host_cpu" in
-  armv5*|armv6*|armv7*) LIBS="-latomic $LIBS"
-esac
-
+# On some platforms, new-style atomics need a helper library
+AC_MSG_CHECKING(whether -latomic is needed)
+AC_LINK_IFELSE([AC_LANG_SOURCE([[
+#include <stdint.h>
+uint64_t v;
+int main() {
+    return (int)__atomic_load_n(&v, __ATOMIC_ACQUIRE);
+}]])], GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=no, GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=yes)
+AC_MSG_RESULT($GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC)
+if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
+    LIBS="-latomic $LIBS"
+fi
 
 PKG_PROG_PKG_CONFIG
 

From feb826725777dc0145910978fa98e60c3d00c115 Mon Sep 17 00:00:00 2001
From: Puck Meerburg <puck@puck.moe>
Date: Fri, 4 Jun 2021 11:25:36 +0000
Subject: [PATCH 3/3] configure.ac: fix use of unread LIBS variable

This fixes both the SunOS/Solaris check, and the libatomic check, which
reference $LIBS, which has not been used since automake was stripped
out of the code.

(cherry picked from commit 196b77b686ab407e4e01fb3ecde07a5f199f4045)
---
 configure.ac | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 8e3e0e5ce..b34e231c2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -69,7 +69,7 @@ AC_SYS_LARGEFILE
 AC_STRUCT_DIRENT_D_TYPE
 if test "$sys_name" = sunos; then
     # Solaris requires -lsocket -lnsl for network functions
-    LIBS="-lsocket -lnsl $LIBS"
+    LDFLAGS="-lsocket -lnsl $LDFLAGS"
 fi
 
 
@@ -167,7 +167,7 @@ int main() {
 }]])], GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=no, GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=yes)
 AC_MSG_RESULT($GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC)
 if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
-    LIBS="-latomic $LIBS"
+    LDFLAGS="-latomic $LDFLAGS"
 fi
 
 PKG_PROG_PKG_CONFIG