Vulkan: Refactor cached compiler instance

ShaderC compiler was cached on the Vulkan backend. The compiler itself
is light-weight and doesn't require any caching. This PR removes the
cached instance from the backend.

Pull Request: https://projects.blender.org/blender/blender/pulls/127693

source/blender/gpu/vulkan/vk_backend.cc

@@ -430,11 +430,6 @@ void VKBackend::render_end()
 
 void VKBackend::render_step() {}
 
-shaderc::Compiler &VKBackend::get_shaderc_compiler()
-{
-  return shaderc_compiler_;
-}
-
 void VKBackend::capabilities_init(VKDevice &device)
 {
   const VkPhysicalDeviceProperties &properties = device.physical_device_properties_get();

source/blender/gpu/vulkan/vk_backend.hh

@@ -17,8 +17,6 @@
 #include "vk_common.hh"
 #include "vk_device.hh"
 
-#include "shaderc/shaderc.hpp"
-
 namespace blender::gpu {
 
 class VKContext;
@@ -27,7 +25,6 @@ class VKDescriptorSetTracker;
 
 class VKBackend : public GPUBackend {
  private:
-  shaderc::Compiler shaderc_compiler_;
 #ifdef WITH_RENDERDOC
   renderdoc::api::Renderdoc renderdoc_api_;
 #endif
@@ -87,8 +84,6 @@ class VKBackend : public GPUBackend {
   bool debug_capture_begin(const char *title);
   void debug_capture_end();
 
-  shaderc::Compiler &get_shaderc_compiler();
-
   static VKBackend &get()
   {
     return *static_cast<VKBackend *>(GPUBackend::get());

source/blender/gpu/vulkan/vk_shader.cc

@@ -513,8 +513,7 @@ Vector<uint32_t> VKShader::compile_glsl_to_spirv(Span<const char *> sources,
                                                  shaderc_shader_kind stage)
 {
   std::string combined_sources = combine_sources(sources);
-  VKBackend &backend = VKBackend::get();
-  shaderc::Compiler &compiler = backend.get_shaderc_compiler();
+  shaderc::Compiler compiler;
   shaderc::CompileOptions options;
   options.SetOptimizationLevel(shaderc_optimization_level_performance);
   options.SetTargetEnvironment(shaderc_target_env_vulkan, shaderc_env_version_vulkan_1_2);

source/blender/gpu/vulkan/vk_shader.hh

@@ -8,13 +8,15 @@
 
 #pragma once
 
+#include "BLI_string_ref.hh"
+
 #include "gpu_shader_private.hh"
 
 #include "vk_backend.hh"
 #include "vk_context.hh"
 #include "vk_push_constants.hh"
 
-#include "BLI_string_ref.hh"
+#include "shaderc/shaderc.hpp"
 
 namespace blender::gpu {
 class VKShaderInterface;