From de818d81c3f9868ca78399fa7f106bed893e540f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Foucault?= <fclem>
Date: Fri, 2 Sep 2022 13:48:55 +0200
Subject: Fix T98190: EEVEE: Very slow rendering on Intel HD Graphics 4400

This particular GPU driver does not constant fold all the way in order
to discard the unused branches.

To workaround that, we introduce a series of material flag that generates
defines that only keep used branches.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D15852
---
 source/blender/gpu/intern/gpu_codegen.cc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

(limited to 'source/blender/gpu/intern')

diff --git a/source/blender/gpu/intern/gpu_codegen.cc b/source/blender/gpu/intern/gpu_codegen.cc
index 82441c3c89c..a05bf51242f 100644
--- a/source/blender/gpu/intern/gpu_codegen.cc
+++ b/source/blender/gpu/intern/gpu_codegen.cc
@@ -351,6 +351,24 @@ void GPUCodegen::generate_resources()
 {
   GPUCodegenCreateInfo &info = *create_info;
 
+  /* Ref. T98190: Defines are optimizations for old compilers.
+   * Might become unecessary with EEVEE-Next. */
+  if (GPU_material_flag_get(&mat, GPU_MATFLAG_PRINCIPLED_CLEARCOAT)) {
+    info.define("PRINCIPLED_CLEARCOAT");
+  }
+  if (GPU_material_flag_get(&mat, GPU_MATFLAG_PRINCIPLED_METALLIC)) {
+    info.define("PRINCIPLED_METALLIC");
+  }
+  if (GPU_material_flag_get(&mat, GPU_MATFLAG_PRINCIPLED_DIELECTRIC)) {
+    info.define("PRINCIPLED_DIELECTRIC");
+  }
+  if (GPU_material_flag_get(&mat, GPU_MATFLAG_PRINCIPLED_GLASS)) {
+    info.define("PRINCIPLED_GLASS");
+  }
+  if (GPU_material_flag_get(&mat, GPU_MATFLAG_PRINCIPLED_ANY)) {
+    info.define("PRINCIPLED_ANY");
+  }
+
   std::stringstream ss;
 
   /* Textures. */
-- 
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