Use atomic operations to modify resource record refcount

* Scary that this has been broken for so long!

renderdoc/core/resource_manager.cpp

@@ -63,9 +63,9 @@ void ResourceRecord::AddResourceReferences(ResourceRecordHandler *mgr)
 
 void ResourceRecord::Delete(ResourceRecordHandler *mgr)
 {
-	RefCount--;
-	RDCASSERT(RefCount >= 0);
-	if(RefCount <= 0)
+	int32_t ref = Atomic::Dec32(&RefCount);
+	RDCASSERT(ref >= 0);
+	if(ref <= 0)
 	{
 		for(auto it = Parents.begin(); it != Parents.end(); ++it)
 			(*it)->Delete(mgr);

renderdoc/core/resource_manager.h

@@ -156,7 +156,7 @@ struct ResourceRecord
 			recordlist.insert(m_Chunks.begin(), m_Chunks.end());
 	}
 
-	void AddRef() { RefCount++; }	
+	void AddRef() { Atomic::Inc32(&RefCount); }	
 	int GetRefCount() const { return RefCount; }
 	void Delete(ResourceRecordHandler *mgr);
 
@@ -269,7 +269,7 @@ struct ResourceRecord
 	bool DataWritten;
 
 protected:
-	int RefCount;
+	volatile int32_t RefCount;
 
 	byte *DataPtr;
 	uint64_t DataOffset;

renderdoc/os/linux/linux_threading.cpp

@@ -52,6 +52,11 @@ namespace Atomic
 	{
 		return __sync_add_and_fetch(i, int32_t(1));
 	}
+	
+	int32_t Dec32(volatile int32_t *i)
+	{
+		return __sync_add_and_fetch(i, int32_t(-1));
+	}
 
 	int64_t Inc64(volatile int64_t *i)
 	{

renderdoc/os/os_specific.h

@@ -166,6 +166,7 @@ namespace Network
 namespace Atomic
 {
 	int32_t Inc32(volatile int32_t *i);
+	int32_t Dec32(volatile int32_t *i);
 	int64_t Inc64(volatile int64_t *i);
 	int64_t Dec64(volatile int64_t *i);
 	int64_t ExchAdd64(volatile int64_t *i, int64_t a);

renderdoc/os/win32/win32_threading.cpp

@@ -54,6 +54,11 @@ namespace Atomic
 	{
 		return (int32_t)InterlockedIncrement((volatile LONG *)i);
 	}
+	
+	int32_t Dec32(volatile int32_t *i)
+	{
+		return (int32_t)InterlockedDecrement((volatile LONG *)i);
+	}
 
 	int64_t Inc64(volatile int64_t *i)
 	{