From 9bea887493d388e3308b15642a366d4aa784a207 Mon Sep 17 00:00:00 2001
From: Alex Dowad <alexinbeijing@gmail.com>
Date: Sat, 9 Aug 2014 13:51:44 +0200
Subject: [PATCH 1/5] Remove now-unneeded test for GCC CAS from extconf.rb

Previously, there was a preprocessor conditional directive in
atomic_reference.c which checked for HAVE_GCC_CAS. It's gone now.
So there is no reason to waste time while compiling.
---
 ext/extconf.rb | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/ext/extconf.rb b/ext/extconf.rb
index 03faf6e..369dec4 100644
--- a/ext/extconf.rb
+++ b/ext/extconf.rb
@@ -37,12 +37,4 @@ def compiler_is_gcc
   end
 end
 
-try_run(<<CODE,$CFLAGS) && ($defs << '-DHAVE_GCC_CAS')
-int main() {
-  int i = 1;
-  __sync_bool_compare_and_swap(&i, 1, 4);
-  return (i != 4);
-}
-CODE
-
 create_makefile(extension_name)

From 793012ea30d9c0180ec5ab10362adfca5a94baff Mon Sep 17 00:00:00 2001
From: Alex Dowad <alexinbeijing@gmail.com>
Date: Sat, 9 Aug 2014 13:56:21 +0200
Subject: [PATCH 2/5] #get/#set have 'volatile' semantics when compiled with
 GCC

---
 ext/atomic_reference.c | 6 ++++++
 ext/extconf.rb         | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/ext/atomic_reference.c b/ext/atomic_reference.c
index 0a09cc6..75f3751 100644
--- a/ext/atomic_reference.c
+++ b/ext/atomic_reference.c
@@ -37,11 +37,17 @@ static VALUE ir_initialize(int argc, VALUE* argv, VALUE self) {
 }
 
 static VALUE ir_get(VALUE self) {
+#if HAVE_GCC_SYNC
+    __sync_synchronize();
+#endif
     return (VALUE) DATA_PTR(self);
 }
 
 static VALUE ir_set(VALUE self, VALUE new_value) {
     DATA_PTR(self) = (void *) new_value;
+#if HAVE_GCC_SYNC
+    __sync_synchronize();
+#endif
     return new_value;
 }
 
diff --git a/ext/extconf.rb b/ext/extconf.rb
index 369dec4..6baa607 100644
--- a/ext/extconf.rb
+++ b/ext/extconf.rb
@@ -37,4 +37,11 @@ def compiler_is_gcc
   end
 end
 
+try_run(<<CODE,$CFLAGS) && ($defs << '-DHAVE_GCC_SYNC')
+int main() {
+  __sync_synchronize();
+  return 0;
+}
+CODE
+
 create_makefile(extension_name)

From c2ab5faafe3cbfb63118e12e8b9f55523cf269c2 Mon Sep 17 00:00:00 2001
From: Alex Dowad <alexinbeijing@gmail.com>
Date: Sat, 9 Aug 2014 14:04:51 +0200
Subject: [PATCH 3/5] #get/#set have 'volatile' semantics when compiled with MS
 Visual C++

---
 ext/atomic_reference.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ext/atomic_reference.c b/ext/atomic_reference.c
index 75f3751..c5b9f78 100644
--- a/ext/atomic_reference.c
+++ b/ext/atomic_reference.c
@@ -39,6 +39,8 @@ static VALUE ir_initialize(int argc, VALUE* argv, VALUE self) {
 static VALUE ir_get(VALUE self) {
 #if HAVE_GCC_SYNC
     __sync_synchronize();
+#elif defined _MSC_VER
+    MemoryBarrier();
 #endif
     return (VALUE) DATA_PTR(self);
 }
@@ -47,6 +49,8 @@ static VALUE ir_set(VALUE self, VALUE new_value) {
     DATA_PTR(self) = (void *) new_value;
 #if HAVE_GCC_SYNC
     __sync_synchronize();
+#elif defined _MSC_VER
+    MemoryBarrier();
 #endif
     return new_value;
 }

From 0318aa503fd856afed6a5936f0e3077ef5022cce Mon Sep 17 00:00:00 2001
From: Alex Dowad <alexinbeijing@gmail.com>
Date: Sat, 9 Aug 2014 14:05:08 +0200
Subject: [PATCH 4/5] #get/#set have 'volatile' semantics when compiled on Mac
 OS X

---
 ext/atomic_reference.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ext/atomic_reference.c b/ext/atomic_reference.c
index c5b9f78..0aefad0 100644
--- a/ext/atomic_reference.c
+++ b/ext/atomic_reference.c
@@ -41,6 +41,8 @@ static VALUE ir_get(VALUE self) {
     __sync_synchronize();
 #elif defined _MSC_VER
     MemoryBarrier();
+#elif __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
+    OSMemoryBarrier();
 #endif
     return (VALUE) DATA_PTR(self);
 }
@@ -51,6 +53,8 @@ static VALUE ir_set(VALUE self, VALUE new_value) {
     __sync_synchronize();
 #elif defined _MSC_VER
     MemoryBarrier();
+#elif __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
+    OSMemoryBarrier();
 #endif
     return new_value;
 }

From a762883cfac9d0a0a87f49167e77be6ac502bbe9 Mon Sep 17 00:00:00 2001
From: Alex Dowad <alexinbeijing@gmail.com>
Date: Sat, 9 Aug 2014 14:06:49 +0200
Subject: [PATCH 5/5] #swap also has 'volatile' semantics

---
 ext/atomic_reference.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/ext/atomic_reference.c b/ext/atomic_reference.c
index 0aefad0..fbbbca1 100644
--- a/ext/atomic_reference.c
+++ b/ext/atomic_reference.c
@@ -60,9 +60,8 @@ static VALUE ir_set(VALUE self, VALUE new_value) {
 }
 
 static VALUE ir_get_and_set(VALUE self, VALUE new_value) {
-    VALUE old_value;
-    old_value = (VALUE) DATA_PTR(self);
-    DATA_PTR(self) = (void *) new_value;
+    VALUE old_value = ir_get(self);
+    ir_set(self, new_value);
     return old_value;
 }