EEVEE: Parallel specialization constants compilation

Convert `Renderbuffers::sync` into `RenderBuffers::init`.
Use `GPU_shaders_precompile_specializations` in EEVEE.

Pull Request: https://projects.blender.org/blender/blender/pulls/122798

source/blender/draw/engines/eevee_next/eevee_instance.cc

@@ -95,6 +95,7 @@ void Instance::init(const int2 &output_res,
   sampling.init(scene);
   camera.init();
   film.init(output_res, output_rect);
+  render_buffers.init();
   ambient_occlusion.init();
   velocity.init();
   raytracing.init();
@@ -135,6 +136,7 @@ void Instance::init_light_bake(Depsgraph *depsgraph, draw::Manager *manager)
   /* Film isn't used but init to avoid side effects in other module. */
   rcti empty_rect{0, 0, 0, 0};
   film.init(int2(1), &empty_rect);
+  render_buffers.init();
   velocity.init();
   depth_of_field.init();
   shadows.init();
@@ -207,7 +209,6 @@ void Instance::begin_sync()
   hiz_buffer.sync();
   main_view.sync();
   film.sync();
-  render_buffers.sync();
   ambient_occlusion.sync();
   volume_probes.sync();
   lookdev.sync();

source/blender/draw/engines/eevee_next/eevee_pipeline.cc

@@ -501,6 +501,30 @@ void DeferredLayerBase::gbuffer_pass_sync(Instance &inst)
 
 void DeferredLayer::begin_sync()
 {
+  if (GPU_use_parallel_compilation()) {
+    /* Pre-compile specialization constants in parallel. */
+    Vector<ShaderSpecialization> specializations;
+    for (int i = 0; i < 3; i++) {
+      GPUShader *sh = inst_.shaders.static_shader_get(eShaderType(DEFERRED_LIGHT_SINGLE + i));
+      for (bool use_split_indirect : {false, true}) {
+        for (bool use_lightprobe_eval : {false, true}) {
+          for (bool use_transmission : {false, true}) {
+            specializations.append(
+                {sh,
+                 {{"render_pass_shadow_id", inst_.render_buffers.data.shadow_id},
+                  {"use_split_indirect", use_split_indirect},
+                  {"use_lightprobe_eval", use_lightprobe_eval},
+                  {"use_transmission", use_transmission},
+                  {"shadow_ray_count", inst_.shadows.get_data().ray_count},
+                  {"shadow_ray_step_count", inst_.shadows.get_data().step_count}}});
+          }
+        }
+      }
+    }
+
+    GPU_shaders_precompile_specializations(specializations);
+  }
+
   {
     prepass_ps_.init();
     /* Textures. */

source/blender/draw/engines/eevee_next/eevee_renderbuffers.cc

@@ -24,7 +24,7 @@
 
 namespace blender::eevee {
 
-void RenderBuffers::sync()
+void RenderBuffers::init()
 {
   const eViewLayerEEVEEPassType enabled_passes = inst_.film.enabled_passes_get();
 

source/blender/draw/engines/eevee_next/eevee_renderbuffers.hh

@@ -63,7 +63,7 @@ class RenderBuffers {
     }
   }
 
-  void sync();
+  void init();
 
   /* Acquires (also ensures) the render buffer before rendering to them. */
   void acquire(int2 extent);