Fix image state merge with secondary command buffers.

If a secondary command buffer referenced an image but its layout is unknown, it remains unknown when merged into a primary command buffer.

renderdoc/driver/vulkan/vk_image_states.cpp

@@ -941,7 +941,15 @@ void ImageState::Merge(rdcflatmap<ResourceId, ImageState> &states,
   {
     if(it == states.end() || dstIt->first < it->first)
     {
-      it = states.insert(it, {dstIt->first, dstIt->second.InitialState()});
+      // If we're merging in an image state our source hasn't seen before, we first add an initial
+      // state for that image, then merge in the current image state. However, if the destination
+      // only referenced the image and never recorded an explicit layout transition the layout of
+      // that image will be unknown. In that case we copy it as-is to avoid improperly recording a
+      // transition back to initial state.
+      if(dstIt->second.subresourceStates.IsInitialised())
+        it = states.insert(it, {dstIt->first, dstIt->second.InitialState()});
+      else
+        it = states.insert(it, *dstIt);
     }
     else if(it->first < dstIt->first)
     {

renderdoc/driver/vulkan/vk_resources.h

@@ -1593,6 +1593,16 @@ public:
     m_value = ImageSubresourceState(VK_QUEUE_FAMILY_IGNORED, UNKNOWN_PREV_IMG_LAYOUT, refType);
   }
 
+  bool IsInitialised() const
+  {
+    // When merging image states from a secondary command buffer into a primary, some of those image
+    // states may have been added in an unknown layout when the image was referenced and never
+    // updated. These cases need to be detected and handled separately, otherwise the layout
+    // transitions recorded to the primary may be improperly overwritten.
+    return (!m_values.empty() || m_value.oldLayout != UNKNOWN_PREV_IMG_LAYOUT ||
+            m_value.newLayout != UNKNOWN_PREV_IMG_LAYOUT);
+  }
+
   void ToArray(rdcarray<ImageSubresourceStateForRange> &arr);
 
   void FromArray(const rdcarray<ImageSubresourceStateForRange> &arr);