From d7e6145acd3d2dba597f69c2679538fe8751cdf0 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Fri, 21 Jan 2011 21:42:04 -0800
Subject: [PATCH] Separated out the minimum functionality that we need from gcc
 for our spinlock fallback.

---
 configure.in              | 12 ++++++++++++
 include/SDL_config.h.in   |  1 +
 src/atomic/SDL_spinlock.c |  2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/configure.in b/configure.in
index c4ae06170..3f1c81f53 100644
--- a/configure.in
+++ b/configure.in
@@ -312,6 +312,18 @@ if test x$enable_gcc_atomics = xyes; then
     if test x$have_gcc_atomics = xyes; then
         AC_DEFINE(HAVE_GCC_ATOMICS)
     fi
+
+    # See if we have the minimum operation needed for GCC atomics
+    AC_TRY_LINK([
+    ],[
+    int a;
+    __sync_lock_test_and_set(&a, 1);
+    ],[
+    have_gcc_sync_lock_test_and_set=yes
+    ])
+    if test x$have_gcc_sync_lock_test_and_set = xyes; then
+        AC_DEFINE(HAVE_GCC_SYNC_LOCK_TEST_AND_SET)
+    fi
 fi
 
 # Standard C sources
diff --git a/include/SDL_config.h.in b/include/SDL_config.h.in
index 491fa1a4b..c0500f0ee 100644
--- a/include/SDL_config.h.in
+++ b/include/SDL_config.h.in
@@ -59,6 +59,7 @@
 #undef SIZEOF_VOIDP
 #undef SDL_HAS_64BIT_TYPE
 #undef HAVE_GCC_ATOMICS
+#undef HAVE_GCC_SYNC_LOCK_TEST_AND_SET
 
 /* Comment this if you want to build without any C library requirements */
 #undef HAVE_LIBC
diff --git a/src/atomic/SDL_spinlock.c b/src/atomic/SDL_spinlock.c
index eebe5631e..2cbd927d7 100644
--- a/src/atomic/SDL_spinlock.c
+++ b/src/atomic/SDL_spinlock.c
@@ -36,7 +36,7 @@ SDL_AtomicTryLock(SDL_SpinLock *lock)
 #elif defined(__MACOSX__)
     return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
 
-#elif defined(HAVE_GCC_ATOMICS)
+#elif defined(HAVE_GCC_SYNC_LOCK_TEST_AND_SET)
     return (__sync_lock_test_and_set(lock, 1) == 0);
 
 #elif defined(__GNUC__) && defined(__arm__) && defined(__ARM_ARCH_5__)