Fix crash when signalling swapchain semaphore using MTLEvent.

Clear out some dead swapchain image code.

Docs/Whats_New.md

@@ -28,6 +28,7 @@ Released TBD
 - Ensure Vulkan loader magic number is set every time before returning any dispatchable Vulkan handle.
 - Fix crash when `VkDeviceCreateInfo` specifies queue families out of numerical order.
 - Fix crash in `vkDestroyPipelineLayout()`.
+- Fix crash when signalling swapchain semaphore using `MTLEvent`.
 - `vkCmdBlitImage()` support format component swizzling.
 - `vkCmdClearImage()` set error if attempt made to clear 1D image, and fix validation of depth attachment formats.
 - `vkCreateRenderPass()` return `VK_ERROR_FORMAT_NOT_SUPPORTED` if format not supported.

MoltenVK/MoltenVK/GPUObjects/MVKImage.h

@@ -414,22 +414,6 @@ public:
 	/** Binds this resource according to the specified bind information. */
 	VkResult bindDeviceMemory2(const void* pBindInfo) override;
 
-	/** Returns the encompassing swapchain. */
-	inline MVKSwapchain* getSwapchain() { return _swapchain; }
-
-	/** Returns the index of this image within the encompassing swapchain. */
-	inline uint32_t getSwapchainIndex() { return _swapchainIndex; }
-
-	/**
-	 * Registers a semaphore and/or fence that will be signaled when this image becomes available.
-	 * This function accepts both a semaphore and a fence, and either none, one, or both may be provided.
-	 * If this image is available already, the semaphore and fence are immediately signaled.
-	 */
-	void signalWhenAvailable(MVKSemaphore* semaphore, MVKFence* fence);
-
-	/** Returns the availability status of this image, relative to other images in the swapchain. */
-	const MVKSwapchainImageAvailability* getAvailability();
-
 	
 #pragma mark Metal
 

MoltenVK/MoltenVK/GPUObjects/MVKImage.mm

@@ -1259,14 +1259,6 @@ VkResult MVKSwapchainImage::bindDeviceMemory2(const void* pBindInfo) {
 	return VK_SUCCESS;
 }
 
-void MVKSwapchainImage::signalWhenAvailable(MVKSemaphore* semaphore, MVKFence* fence) {
-	_swapchain->signalWhenAvailable( _swapchainIndex, semaphore, fence );
-}
-
-const MVKSwapchainImageAvailability* MVKSwapchainImage::getAvailability() {
-	return _swapchain->getAvailability( _swapchainIndex );
-}
-
 
 #pragma mark Metal
 

MoltenVK/MoltenVK/GPUObjects/MVKSwapchain.h

@@ -87,9 +87,7 @@ public:
 	 */
 	void signalWhenAvailable(uint32_t imageIndex, MVKSemaphore* semaphore, MVKFence* fence);
 
-	/** Returns the availability status of the image at the given index, relative to other images in the swapchain. */
+	
-	const MVKSwapchainImageAvailability* getAvailability(uint32_t imageIndex);
-
 #pragma mark Metal
 
 	/** 

MoltenVK/MoltenVK/GPUObjects/MVKSwapchain.mm

@@ -136,18 +136,18 @@ void MVKSwapchain::makeAvailable(uint32_t imgIdx) {
 
 	MVKSwapchainSignaler signaler;
 	if (availability.isAvailable) {
-		// If this image is now available, signal the semaphore and fence that were associated
+		// If this image is available, signal the semaphore and fence that were associated
 		// with the last time this image was acquired while available. This is a workaround for
 		// when an app uses a single semaphore or fence for more than one swapchain image.
 		// Becuase the semaphore or fence will be signaled by more than one image, it will
 		// get out of sync, and the final use of the image would not be signaled as a result.
-
 		signaler = _imageAvailability[imgIdx].preSignaled;
 	} else {
 		// If this image is not yet available, extract and signal the first semaphore and fence.
-
+		auto& imgSignalers = _imageAvailability[imgIdx].signalers;
-		signaler = _imageAvailability[imgIdx].signalers.front();
+		auto sigIter = imgSignalers.begin();
-		_imageAvailability[imgIdx].signalers.erase( _imageAvailability[imgIdx].signalers.begin() );
+		signaler = *sigIter;
+		imgSignalers.erase(sigIter);
 	}
 
 	// Signal the semaphore and fence, and let them know they are no longer being tracked.
@@ -191,8 +191,11 @@ void MVKSwapchain::signal(MVKSwapchainSignaler& signaler) {
 // If present, signal the semaphore for the first waiter for the given image.
 void MVKSwapchain::signalOnDevice(uint32_t imgIdx, id<MTLCommandBuffer> mtlCmdBuff) {
 	lock_guard<mutex> lock(_availabilityLock);
-	MVKSemaphore* mvkSem = _imageAvailability[imgIdx].signalers.front().first;
+	auto& imgSignalers = _imageAvailability[imgIdx].signalers;
-	if (mvkSem) { mvkSem->encodeSignal(mtlCmdBuff); }
+	if ( !imgSignalers.empty() ) {
+		MVKSemaphore* mvkSem = imgSignalers.front().first;
+		if (mvkSem) { mvkSem->encodeSignal(mtlCmdBuff); }
+	}
 }
 
 // Tell the semaphore and fence that they are being tracked for future signaling.
@@ -207,13 +210,6 @@ void MVKSwapchain::unmarkAsTracked(MVKSwapchainSignaler& signaler) {
 	if (signaler.second) { signaler.second->release(); }
 }
 
-const MVKSwapchainImageAvailability* MVKSwapchain::getAvailability(uint32_t imageIndex) {
-	lock_guard<mutex> lock(_availabilityLock);
-	auto& availability = _imageAvailability[imageIndex].status;
-	availability.waitCount = (uint32_t)_imageAvailability[imageIndex].signalers.size();
-	return &availability;
-}
-
 
 #pragma mark Rendering