Follow the spec strictly - only coherent memory is 'implicitly flushed'

* Technically coherent memory isn't implicitly flushed either, but this
  is handling is required if memory is mapped, written to, and unmapped
  without ever hitting a QueueSubmit where we will check any current
  coherent map, and treat it as persistent to flush it out.

renderdoc/driver/vulkan/wrappers/vk_resource_funcs.cpp

@@ -417,7 +417,13 @@ void WrappedVulkan::vkUnmapMemory(
 
 			if(capframe)
 			{
-				if(!state.mapFlushed)
+				// coherent maps must always serialise all data on unmap, even if a flush was seen, because
+				// unflushed data is *also* visible. This is a bit redundant since data is serialised here
+				// and in any flushes, but that's the app's fault - the spec calls out flushing coherent maps
+				// as inefficient
+				// if the memory is not coherent, we must have a flush for every region written while it is 
+				// mapped, there is no implicit flush on unmap, so we follow the spec strictly on this.
+				if(state.mapCoherent)
 				{
 					CACHE_THREAD_SERIALISER();
 
@@ -436,11 +442,6 @@ void WrappedVulkan::vkUnmapMemory(
 						GetResourceManager()->MarkResourceFrameReferenced(id, eFrameRef_Write);
 					}
 				}
-				else
-				{
-					// VKTODOLOW for now assuming flushes cover all writes. Technically
-					// this is true for all non-coherent memory types.
-				}
 			}
 
 			state.mappedPtr = NULL;