Prevent compilation of redundant pipelines (#9681)

If we've already destroyed a program, we shouldn't run prewarm for it,
as that could entail five pipeline compilations.

Author: anishmgoyal

filament/backend/src/vulkan/VulkanDriver.cpp

@@ -902,6 +902,7 @@ void VulkanDriver::destroyProgram(Handle<HwProgram> ph) {
         return;
     }
     auto vprogram = resource_ptr<VulkanProgram>::cast(&mResourceManager, ph);
+    vprogram->cancelParallelCompilation();
     vprogram.dec();
 }
 

filament/backend/src/vulkan/VulkanHandles.h

@@ -262,6 +262,14 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
     VulkanProgram(VkDevice device, Program const& builder) noexcept;
     ~VulkanProgram();
 
+    /**
+     * Cancels any parallel compilation jobs that have not yet run for this
+     * program.
+     */
+    inline void cancelParallelCompilation() {
+        mParallelCompilationCanceled.store(true, std::memory_order_release);
+    }
+
     /**
      * Writes out any queued push constants using the provided VkPipelineLayout.
      *
@@ -284,6 +292,17 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
         return mInfo->pushConstantDescription.getVkRanges();
     }
 
+    /**
+     * Returns true if parallel compilation is canceled, false if not. Parallel
+     * compilation will be canceled if this program is destroyed before relevant
+     * pipelines are created.
+     *
+     * @return true if parallel compilation should run for this program, false if not
+     */
+    inline bool isParallelCompilationCanceled() const {
+        return mParallelCompilationCanceled.load(std::memory_order_acquire);
+    }
+
     inline void writePushConstant(VkCommandBuffer cmdbuf, VkPipelineLayout layout,
             backend::ShaderStage stage, uint8_t index, backend::PushConstantVariant const& value) {
         // It's possible that we don't have the layout yet. When external samplers are used, bindPipeline()
@@ -320,6 +339,7 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
 
     PipelineInfo* mInfo;
     VkDevice mDevice = VK_NULL_HANDLE;
+    std::atomic<bool> mParallelCompilationCanceled { false };
     std::vector<PushConstantInfo> mQueuedPushConstants;
 };
 

filament/backend/src/vulkan/VulkanPipelineCache.cpp

@@ -178,9 +178,14 @@ void VulkanPipelineCache::asyncPrewarmCache(
     CallbackManager::Handle cmh = mCallbackManager.get();
     auto token = std::make_shared<ProgramToken>();
     // Note: we keep a ref to vprogram in this lambda so that the shader modules don't get
-    // destroyed before we call createPipeline(). This is rare enough that we are ok with
-    // occasionally creating pipelines for destroyed materials.
+    // destroyed before we call createPipeline(). We can catch this in some cases, to avoid
+    // compiling too many unnecessary already-destroyed-materials.
     mCompilerThreadPool.queue(priority, token, [this, vprogram, key, dynamicOptions, cmh]() mutable {
+        if (vprogram->isParallelCompilationCanceled()) {
+            FVK_LOGD << "Skipping prewarm for a program that has been destroyed already.";
+            return;
+        }
+
         VkPipeline pipeline = createPipeline(key, dynamicOptions);
         mCallbackManager.put(cmh);
         // We don't actually need this pipeline, we just wanted to force the driver to cache