From 0ee15222c83157dc765a9fdeac614e1620f76d12 Mon Sep 17 00:00:00 2001
From: Bill Hollings <bill.hollings@brenwill.com>
Date: Fri, 8 Sep 2023 20:46:28 -0400
Subject: [PATCH] Ensure objects retained for life of MTLCommandBuffer.

- vkCmdBlitImage() ensure swizzle texture view is retained for life
  of MTLCommandBuffer.
- vkQueuePresentKHR() use MTLCommandBuffer that retains references.
- Update MoltenVK version to 1.2.6.
---
 Docs/Whats_New.md                            |  1 +
 MoltenVK/MoltenVK/API/mvk_config.h           |  2 +-
 MoltenVK/MoltenVK/Commands/MVKCmdTransfer.mm | 19 ++++++++-----------
 MoltenVK/MoltenVK/GPUObjects/MVKQueue.mm     |  5 ++++-
 4 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/Docs/Whats_New.md b/Docs/Whats_New.md
index 836a60a9..605cda82 100644
--- a/Docs/Whats_New.md
+++ b/Docs/Whats_New.md
@@ -20,6 +20,7 @@ Released TBD
 
 - Fix rare case where vertex attribute buffers are not bound to Metal 
   when no other bindings change between pipelines.
+- Ensure objects retained for life of `MTLCommandBuffer` during `vkCmdBlitImage()` & `vkQueuePresentKHR()`.
 - Fix case where a `CAMetalDrawable` with invalid pixel format causes onscreen flickering.
 - Improve behavior of swapchain image presentation stalls caused by Metal regression.
 - Add several additional performance trackers, available via logging, or the `mvk_private_api.h` API.
diff --git a/MoltenVK/MoltenVK/API/mvk_config.h b/MoltenVK/MoltenVK/API/mvk_config.h
index 532d27db..f9702661 100644
--- a/MoltenVK/MoltenVK/API/mvk_config.h
+++ b/MoltenVK/MoltenVK/API/mvk_config.h
@@ -45,7 +45,7 @@ extern "C" {
  */
 #define MVK_VERSION_MAJOR   1
 #define MVK_VERSION_MINOR   2
-#define MVK_VERSION_PATCH   5
+#define MVK_VERSION_PATCH   6
 
 #define MVK_MAKE_VERSION(major, minor, patch)    (((major) * 10000) + ((minor) * 100) + (patch))
 #define MVK_VERSION     MVK_MAKE_VERSION(MVK_VERSION_MAJOR, MVK_VERSION_MINOR, MVK_VERSION_PATCH)
diff --git a/MoltenVK/MoltenVK/Commands/MVKCmdTransfer.mm b/MoltenVK/MoltenVK/Commands/MVKCmdTransfer.mm
index 2c0ef546..1c38d15a 100644
--- a/MoltenVK/MoltenVK/Commands/MVKCmdTransfer.mm
+++ b/MoltenVK/MoltenVK/Commands/MVKCmdTransfer.mm
@@ -504,11 +504,12 @@ void MVKCmdBlitImage<N>::encode(MVKCommandEncoder* cmdEncoder, MVKCommandUse com
 			if (cmdEncoder->getDevice()->_pMetalFeatures->nativeTextureSwizzle &&
 				_srcImage->needsSwizzle()) {
 				// Use a view that has a swizzle on it.
-				srcMTLTex = [[srcMTLTex newTextureViewWithPixelFormat:srcMTLTex.pixelFormat
-														  textureType:srcMTLTex.textureType
-															   levels:NSMakeRange(0, srcMTLTex.mipmapLevelCount)
-															   slices:NSMakeRange(0, srcMTLTex.arrayLength)
-															  swizzle:_srcImage->getPixelFormats()->getMTLTextureSwizzleChannels(_srcImage->getVkFormat())] autorelease];
+				srcMTLTex = [srcMTLTex newTextureViewWithPixelFormat:srcMTLTex.pixelFormat
+														 textureType:srcMTLTex.textureType
+															  levels:NSMakeRange(0, srcMTLTex.mipmapLevelCount)
+															  slices:NSMakeRange(0, srcMTLTex.arrayLength)
+															 swizzle:_srcImage->getPixelFormats()->getMTLTextureSwizzleChannels(_srcImage->getVkFormat())];
+				[cmdEncoder->_mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer>) { [srcMTLTex release]; }];
 			}
             cmdEncoder->endCurrentMetalEncoding();
 
@@ -551,9 +552,7 @@ void MVKCmdBlitImage<N>::encode(MVKCommandEncoder* cmdEncoder, MVKCommandUse com
                                                          textureType: MTLTextureType2DArray
                                                               levels: NSMakeRange(0, srcMTLTex.mipmapLevelCount)
                                                               slices: NSMakeRange(0, srcMTLTex.arrayLength)];
-                [cmdEncoder->_mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer>) {
-                    [srcMTLTex release];
-                }];
+                [cmdEncoder->_mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer>) { [srcMTLTex release]; }];
             }
             blitKey.dstMTLPixelFormat = _dstImage->getMTLPixelFormat(dstPlaneIndex);
             blitKey.srcFilter = mvkMTLSamplerMinMagFilterFromVkFilter(_filter);
@@ -655,9 +654,7 @@ void MVKCmdBlitImage<N>::encode(MVKCommandEncoder* cmdEncoder, MVKCommandUse com
 #endif
                         }
                         id<MTLTexture> stencilMTLTex = [srcMTLTex newTextureViewWithPixelFormat: stencilFmt];
-                        [cmdEncoder->_mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer>) {
-                            [stencilMTLTex release];
-                        }];
+                        [cmdEncoder->_mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer>) { [stencilMTLTex release]; }];
                         [mtlRendEnc setFragmentTexture: stencilMTLTex atIndex: 1];
                     } else {
                         [mtlRendEnc setFragmentTexture: srcMTLTex atIndex: 1];
diff --git a/MoltenVK/MoltenVK/GPUObjects/MVKQueue.mm b/MoltenVK/MoltenVK/GPUObjects/MVKQueue.mm
index f53cb71d..1c28f63f 100644
--- a/MoltenVK/MoltenVK/GPUObjects/MVKQueue.mm
+++ b/MoltenVK/MoltenVK/GPUObjects/MVKQueue.mm
@@ -622,7 +622,10 @@ MVKQueueFullCommandBufferSubmission<N>::MVKQueueFullCommandBufferSubmission(MVKQ
 // If the semaphores are not encodable, wait on them inline after presenting.
 // The semaphores know what to do.
 VkResult MVKQueuePresentSurfaceSubmission::execute() {
-	id<MTLCommandBuffer> mtlCmdBuff = _queue->getMTLCommandBuffer(kMVKCommandUseQueuePresent);
+	// MTLCommandBuffer retain references to avoid rare case where objects are destroyed too early. 
+	// Although testing could not determine which objects were being lost, queue present MTLCommandBuffers
+	// are used only once per frame, and retain so few objects, that blanket retention is still performant.
+	id<MTLCommandBuffer> mtlCmdBuff = _queue->getMTLCommandBuffer(kMVKCommandUseQueuePresent, true);
 
 	for (auto& ws : _waitSemaphores) {
 		auto& sem4 = ws.first;