layers: Don't insist on memory dependency for present

When transitioning to/from VK_IMAGE_LAYOUT_PRESENT_SRC_KHR we don't need
to insist on VK_ACCESS_MEMORY_READ_BIT. On the transition TO, it's
automatically handled; in the transition FROM, it's a WAR hazard rather
than RAW/WAW so only the execution dependency is needed.

Fixes #1717.

1 files changed, 11 insertions, 4 deletions

diff --git a/layers/buffer_validation.cpp b/layers/buffer_validation.cpp
index ec8016f5..d5b15cb8 100644
--- a/layers/buffer_validation.cpp
+++ b/layers/buffer_validation.cpp
@@ -2078,10 +2078,6 @@ bool ValidateMaskBitsFromLayouts(core_validation::layer_data *device_data, VkCom
             skip |= ValidateMaskBits(device_data, cmdBuffer, accessMask, layout, VK_ACCESS_TRANSFER_READ_BIT, 0, type);
             break;
         }
-        case VK_IMAGE_LAYOUT_PRESENT_SRC_KHR: {
-            skip |= ValidateMaskBits(device_data, cmdBuffer, accessMask, layout, VK_ACCESS_MEMORY_READ_BIT, 0, type);
-            break;
-        }
         case VK_IMAGE_LAYOUT_UNDEFINED: {
             if (accessMask != 0) {
                 // TODO: Verify against Valid Use section spec
@@ -2092,6 +2088,17 @@ bool ValidateMaskBitsFromLayouts(core_validation::layer_data *device_data, VkCom
             }
             break;
         }
+        case VK_IMAGE_LAYOUT_PRESENT_SRC_KHR:
+            // Notes: QueuePresentKHR performs automatic visibility operations,
+            // so the app is /NOT/ required to include VK_ACCESS_MEMORY_READ_BIT
+            // when transitioning to this layout.
+            //
+            // When transitioning /from/ this layout, the application needs to
+            // avoid only a WAR hazard -- any writes need to be ordered after
+            // the PE's reads. There is no need for a memory dependency for this
+            // case.
+            /* fallthrough */
+
         case VK_IMAGE_LAYOUT_GENERAL:
         default: { break; }
     }