Certain material node graphs can be very expensive to run. This feature aims to produce secondary GPUPass shaders within a GPUMaterial which provide optimal runtime performance. Such optimizations include baking constant data into the shader source directly, allowing the compiler to propogate constants and perform aggressive optimization upfront.

As optimizations can result in reduction of shader editor and animation interactivity, optimized pass generation and compilation is deferred until all outstanding compilations have completed. Optimization is also delayed util a material has remained unmodified for a set period of time, to reduce excessive compilation. The original variant of the material shader is kept to maintain interactivity.

Also adding a new concept to gpu::Shader allowing assignment of a parent shader from which a shader can pull PSO descriptors and any required metadata for asynchronous shader cache warming. This enables fully asynchronous shader optimization, without runtime hitching, while also reducing runtime hitching for standard materials, by using PSO descriptors from default materials, ahead of rendering.

Further shader graph optimizations are likely also possible with this architecture. Certain scenes, such as Wanderer benefit significantly. Viewport performance for this scene is 2-3x faster on Apple-silicon based GPUs.

Authored by Apple: Michael Parkin-White

Ref T96261

@@ -1394,2 +1393,2 @@
-      break;
-    case GPU_MAT_QUEUED:
+    case GPU_MAT_SUCCESS: {
+      /* Detemrine optimization status. */

@@ -1397,2 +1402,2 @@
-      mat = EEVEE_material_default_get(scene, ma, options);
-      break;
+      GPUMaterial *default_mat = EEVEE_material_default_get(scene, ma, options);
+      /* Mark pending material with its default material for future cache warming.*/

@@ -275,2 +286,4 @@
 bool GPU_material_optimization_ready(GPUMaterial *mat);
 
+/**
+ * Store reference to default material for async PSO cache warming.

@@ -109,0 +109,4 @@
+/* Shader cache warming. Cache can be warmed using PSO descriptors
+ * from a specified parent shader. */
+void GPU_shader_set_parent(GPUShader *shader, GPUShader *parent);
+void GPU_shader_warm_cache(GPUShader *shader, int limit);