dtoolbase: Change DeletedBufferChain to use new C++11-style atomics

dtool/src/dtoolbase/deletedBufferChain.I

@@ -27,7 +27,7 @@ validate(void *ptr) {
 
 #if defined(USE_DELETEDCHAINFLAG) && defined(USE_DELETED_CHAIN)
   const ObjectNode *obj = buffer_to_node(ptr);
-  return AtomicAdjust::get(obj->_flag) == DCF_alive;
+  return obj->_flag.load(std::memory_order_relaxed) == DCF_alive;
 #else
   return true;
 #endif  // USE_DELETEDCHAINFLAG

dtool/src/dtoolbase/deletedBufferChain.cxx

@@ -50,8 +50,8 @@ allocate(size_t size, TypeHandle type_handle) {
     _lock.unlock();
 
 #ifdef USE_DELETEDCHAINFLAG
-    assert(obj->_flag == (AtomicAdjust::Integer)DCF_deleted);
-    obj->_flag = DCF_alive;
+    DeletedChainFlag orig_flag = obj->_flag.exchange(DCF_alive, std::memory_order_relaxed);
+    assert(orig_flag == DCF_deleted);
 #endif  // USE_DELETEDCHAINFLAG
 
     void *ptr = node_to_buffer(obj);
@@ -75,7 +75,7 @@ allocate(size_t size, TypeHandle type_handle) {
   obj = (ObjectNode *)(aligned - flag_reserved_bytes);
 
 #ifdef USE_DELETEDCHAINFLAG
-  obj->_flag = DCF_alive;
+  obj->_flag.store(DCF_alive, std::memory_order_relaxed);
 #endif  // USE_DELETEDCHAINFLAG
 
   void *ptr = node_to_buffer(obj);
@@ -116,14 +116,16 @@ deallocate(void *ptr, TypeHandle type_handle) {
   ObjectNode *obj = buffer_to_node(ptr);
 
 #ifdef USE_DELETEDCHAINFLAG
-  AtomicAdjust::Integer orig_flag = AtomicAdjust::compare_and_exchange(obj->_flag, DCF_alive, DCF_deleted);
-
-  // If this assertion is triggered, you double-deleted an object.
-  assert(orig_flag != (AtomicAdjust::Integer)DCF_deleted);
-
-  // If this assertion is triggered, you tried to delete an object that was
-  // never allocated, or you have heap corruption.
-  assert(orig_flag == (AtomicAdjust::Integer)DCF_alive);
+  DeletedChainFlag orig_flag = DCF_alive;
+  if (UNLIKELY(!obj->_flag.compare_exchange_strong(orig_flag, DCF_deleted,
+                                                   std::memory_order_relaxed))) {
+    // If this assertion is triggered, you double-deleted an object.
+    assert(orig_flag != DCF_deleted);
+
+    // If this assertion is triggered, you tried to delete an object that was
+    // never allocated, or you have heap corruption.
+    assert(orig_flag == DCF_alive);
+  }
 #endif  // USE_DELETEDCHAINFLAG
 
   _lock.lock();

dtool/src/dtoolbase/deletedBufferChain.h

@@ -20,6 +20,7 @@
 #include "atomicAdjust.h"
 #include "numeric_types.h"
 #include "typeHandle.h"
+#include "patomic.h"
 #include <assert.h>
 
 // Though it's tempting, it doesn't seem to be possible to implement
@@ -37,7 +38,7 @@
 #endif // NDEBUG
 
 #ifdef USE_DELETEDCHAINFLAG
-enum DeletedChainFlag {
+enum DeletedChainFlag : unsigned int {
   DCF_deleted = 0xfeedba0f,
   DCF_alive = 0x12487654,
 };
@@ -73,7 +74,7 @@ private:
     // In development mode, we piggyback this extra data.  This is maintained
     // out-of-band from the actual pointer returned, so we can safely use this
     // flag to indicate the difference between allocated and freed pointers.
-    TVOLATILE AtomicAdjust::Integer _flag;
+    patomic<DeletedChainFlag> _flag;
 #endif
 
     // This pointer sits within the buffer, in the same space referenced by