Fix initialization of LRU cache keys

src/Device/Blitter.hpp

@@ -20,7 +20,7 @@
 #include "Vulkan/VkFormat.h"
 
 #include <mutex>
-#include <string.h>
+#include <cstring>
 
 namespace vk
 {
@@ -59,15 +59,16 @@ namespace sw
 			bool clampToEdge : 1;
 		};
 
-		struct State : Options
+		struct State : Memset<State>, Options
 		{
-			State() = default;
-			State(const Options &options) : Options(options) {}
+			State() : Memset(this, 0) {}
+			State(const Options &options) : Memset(this, 0), Options(options) {}
 			State(vk::Format sourceFormat, vk::Format destFormat, int srcSamples, int destSamples, const Options &options) :
-				Options(options), sourceFormat(sourceFormat), destFormat(destFormat), srcSamples(srcSamples), destSamples(destSamples) {}
+				Memset(this, 0), Options(options), sourceFormat(sourceFormat), destFormat(destFormat), srcSamples(srcSamples), destSamples(destSamples) {}
 
 			bool operator==(const State &state) const
 			{
+				static_assert(is_memcmparable<State>::value, "Cannot memcmp State");
 				return memcmp(this, &state, sizeof(State)) == 0;
 			}
 

src/Device/LRUCache.hpp

@@ -17,6 +17,9 @@
 
 #include "System/Math.hpp"
 
+#include <cstring>
+#include <type_traits>
+
 namespace sw
 {
 	template<class Key, class Data>
@@ -29,7 +32,7 @@ namespace sw
 
 		Data *query(const Key &key) const;
 		Data *add(const Key &key, Data *data);
-	
+
 		int getSize() {return size;}
 		Key &getKey(int i) {return key[i];}
 
@@ -43,6 +46,32 @@ namespace sw
 		Key **ref;
 		Data **data;
 	};
+
+	// Helper class for clearing the memory of objects at construction.
+	// Useful as the first base class or cache keys which may contain padding bytes or bits otherwise left uninitialized.
+	template<class T>
+	struct Memset
+	{
+		Memset(T *object, int val)
+		{
+			static_assert(std::is_base_of<Memset<T>, T>::value, "Memset<T> must only clear the memory of a type of which it is a base class");
+			memset(object, 0, sizeof(T));
+		}
+	};
+
+	// Traits-like helper class for checking if objects can be compared using memcmp().
+	// Useful for statically asserting if a cache key can implement operator==() with memcmp().
+	template<typename T>
+	struct is_memcmparable
+	{
+		// std::is_trivially_copyable is not available in older GCC versions.
+		#if !defined(__GNUC__) || __GNUC__ > 5
+			static const bool value = std::is_trivially_copyable<T>::value;
+		#else
+			// At least check it doesn't have virtual methods.
+			static const bool value = !std::is_polymorphic<T>::value;
+		#endif
+	};
 }
 
 namespace sw