From d39ac94c41a8502e06ee7942bc6b8bebde40cf88 Mon Sep 17 00:00:00 2001
From: Dario <dariosamo@gmail.com>
Date: Wed, 5 Feb 2025 14:55:52 -0300
Subject: [PATCH] Add loop annotations to ubershaders to prevent loop
unrolling.
---
.../shaders/scene_forward_lights_inc.glsl | 26 +++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/servers/rendering/renderer_rd/shaders/scene_forward_lights_inc.glsl b/servers/rendering/renderer_rd/shaders/scene_forward_lights_inc.glsl
index 41861c5bb9a7..5296b96c9c6f 100644
--- a/servers/rendering/renderer_rd/shaders/scene_forward_lights_inc.glsl
+++ b/servers/rendering/renderer_rd/shaders/scene_forward_lights_inc.glsl
@@ -1,5 +1,18 @@
// Functions related to lighting
+#extension GL_EXT_control_flow_attributes : require
+
+// This annotation macro must be placed before any loops that rely on specialization constants as their upper bound.
+// Drivers may choose to unroll these loops based on the possible range of the value that can be deduced from the
+// spec constant, which can lead to their code generation taking a much longer time than desired.
+#ifdef UBERSHADER
+// Prefer to not unroll loops on the ubershader to reduce code size as much as possible.
+#define SPEC_CONSTANT_LOOP_ANNOTATION [[dont_unroll]]
+#else
+// Don't make an explicit hint on specialized shaders.
+#define SPEC_CONSTANT_LOOP_ANNOTATION
+#endif
+
float D_GGX(float cos_theta_m, float alpha) {
float a = cos_theta_m * alpha;
float k = alpha / (1.0 - cos_theta_m * cos_theta_m + a * a);
@@ -257,6 +270,7 @@ float sample_directional_pcf_shadow(texture2D shadow, vec2 shadow_pixel_size, ve
float avg = 0.0;
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_directional_soft_shadow_samples(); i++) {
avg += textureProj(sampler2DShadow(shadow, shadow_sampler), vec4(pos + shadow_pixel_size * (disk_rotation * scene_data_block.data.directional_soft_shadow_kernel[i].xy), depth, 1.0));
}
@@ -283,6 +297,7 @@ float sample_pcf_shadow(texture2D shadow, vec2 shadow_pixel_size, vec3 coord, fl
float avg = 0.0;
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_soft_shadow_samples(); i++) {
avg += textureProj(sampler2DShadow(shadow, shadow_sampler), vec4(pos + shadow_pixel_size * (disk_rotation * scene_data_block.data.soft_shadow_kernel[i].xy), depth, 1.0));
}
@@ -309,6 +324,7 @@ float sample_omni_pcf_shadow(texture2D shadow, float blur_scale, vec2 coord, vec
float avg = 0.0;
vec2 offset_scale = blur_scale * 2.0 * scene_data_block.data.shadow_atlas_pixel_size / uv_rect.zw;
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_soft_shadow_samples(); i++) {
vec2 offset = offset_scale * (disk_rotation * scene_data_block.data.soft_shadow_kernel[i].xy);
vec2 sample_coord = coord + offset;
@@ -346,6 +362,7 @@ float sample_directional_soft_shadow(texture2D shadow, vec3 pssm_coord, vec2 tex
disk_rotation = mat2(vec2(cr, -sr), vec2(sr, cr));
}
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_directional_penumbra_shadow_samples(); i++) {
vec2 suv = pssm_coord.xy + (disk_rotation * scene_data_block.data.directional_penumbra_shadow_kernel[i].xy) * tex_scale;
float d = textureLod(sampler2D(shadow, SAMPLER_LINEAR_CLAMP), suv, 0.0).r;
@@ -362,6 +379,8 @@ float sample_directional_soft_shadow(texture2D shadow, vec3 pssm_coord, vec2 tex
tex_scale *= penumbra;
float s = 0.0;
+
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_directional_penumbra_shadow_samples(); i++) {
vec2 suv = pssm_coord.xy + (disk_rotation * scene_data_block.data.directional_penumbra_shadow_kernel[i].xy) * tex_scale;
s += textureProj(sampler2DShadow(shadow, shadow_sampler), vec4(suv, pssm_coord.z, 1.0));
@@ -465,6 +484,7 @@ void light_process_omni(uint idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 v
tangent *= omni_lights.data[idx].soft_shadow_size * omni_lights.data[idx].soft_shadow_scale;
bitangent *= omni_lights.data[idx].soft_shadow_size * omni_lights.data[idx].soft_shadow_scale;
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_penumbra_shadow_samples(); i++) {
vec2 disk = disk_rotation * scene_data_block.data.penumbra_shadow_kernel[i].xy;
@@ -501,6 +521,8 @@ void light_process_omni(uint idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 v
z_norm += omni_lights.data[idx].inv_radius * omni_lights.data[idx].shadow_bias;
shadow = 0.0;
+
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_penumbra_shadow_samples(); i++) {
vec2 disk = disk_rotation * scene_data_block.data.penumbra_shadow_kernel[i].xy;
vec3 pos = local_vert + tangent * disk.x + bitangent * disk.y;
@@ -757,6 +779,8 @@ void light_process_spot(uint idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 v
float uv_size = spot_lights.data[idx].soft_shadow_size * z_norm * spot_lights.data[idx].soft_shadow_scale;
vec2 clamp_max = spot_lights.data[idx].atlas_rect.xy + spot_lights.data[idx].atlas_rect.zw;
+
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_penumbra_shadow_samples(); i++) {
vec2 suv = shadow_uv + (disk_rotation * scene_data_block.data.penumbra_shadow_kernel[i].xy) * uv_size;
suv = clamp(suv, spot_lights.data[idx].atlas_rect.xy, clamp_max);
@@ -774,6 +798,8 @@ void light_process_spot(uint idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 v
uv_size *= penumbra;
shadow = 0.0;
+
+ SPEC_CONSTANT_LOOP_ANNOTATION
for (uint i = 0; i < sc_penumbra_shadow_samples(); i++) {
vec2 suv = shadow_uv + (disk_rotation * scene_data_block.data.penumbra_shadow_kernel[i].xy) * uv_size;
suv = clamp(suv, spot_lights.data[idx].atlas_rect.xy, clamp_max);