feat: add an in-game performance panel (#1090)

Add in-game performance panel

Co-authored-by: nmzik <Nmzik@mail.ru>

src/kernel/memory.h

@@ -15,6 +15,23 @@ namespace Libs::LibKernel::Memory {
 void Initialize();
 void Shutdown();
 
+// Guest memory usage for the performance panel. Takes only bookkeeping locks, so it never
+// waits on the GPU; call it only while the memory subsystem is initialized.
+struct DebugStats {
+	uint64_t direct_total        = 0;
+	uint64_t direct_allocated    = 0; // sceKernelAllocateDirectMemory.
+	uint64_t pooled_allocated    = 0; // Memory pool expansions.
+	uint64_t automatic_allocated = 0; // Extended memory.
+	uint64_t direct_mapped       = 0;
+	uint64_t flexible_total      = 0;
+	uint64_t flexible_used       = 0;
+	uint64_t pool_committed      = 0;
+	uint64_t cpu_page_entries    = 0; // 2 MiB page-table entries in use.
+	uint64_t gpu_page_entries    = 0;
+	uint64_t page_entries_total  = 0; // Per side.
+};
+[[nodiscard]] DebugStats GetDebugStats();
+
 struct Lifecycle {
 	static constexpr const char* name       = "Memory";
 	static constexpr auto        initialize = Libs::LibKernel::Memory::Initialize;