VideoBackend/OGL: Prefer KHR_subgroup over NV_shader_thread.

While the NV extension is totally fine, the KHR extension should be able to support more hardware.

For NVIDIA, the hardware either supports both or neither, it just needs a driver from the last two years.
For AMD, the drivers from late 2022-12 seems to bring support for the KHR extension.
For Intel, the KHR is also supported for some years.

1 files changed, 11 insertions, 16 deletions

diff --git a/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp b/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
index 289e99cae0..eff1497e7f 100644
--- a/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
+++ b/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
@@ -78,6 +78,8 @@ static std::string GetGLSLVersionString()
     return "#version 400";
   case Glsl430:
     return "#version 430";
+  case Glsl450:
+    return "#version 450";
   default:
     // Shouldn't ever hit this
     return "#version ERROR";
@@ -720,25 +722,18 @@ void ProgramShaderCache::CreateHeader()
   }
 
   std::string shader_shuffle_string;
-  if (g_ogl_config.bSupportsShaderThreadShuffleNV)
+  if (g_ogl_config.bSupportsKHRShaderSubgroup)
   {
     shader_shuffle_string = R"(
-#extension GL_NV_shader_thread_group : enable
-#extension GL_NV_shader_thread_shuffle : enable
-#define SUPPORTS_SUBGROUP_REDUCTION 1
+#extension GL_KHR_shader_subgroup_basic : enable
+#extension GL_KHR_shader_subgroup_arithmetic : enable
+#extension GL_KHR_shader_subgroup_ballot : enable
 
-// The xor shuffle below produces incorrect results if all threads in a warp are not active.
-#define CAN_USE_SUBGROUP_REDUCTION (ballotThreadNV(true) == 0xFFFFFFFFu)
-
-#define IS_HELPER_INVOCATION gl_HelperThreadNV
-#define IS_FIRST_ACTIVE_INVOCATION (gl_ThreadInWarpNV == findLSB(ballotThreadNV(!gl_HelperThreadNV)))
-#define SUBGROUP_REDUCTION(func, value) value = func(value, shuffleXorNV(value, 16, 32)); \
-                                        value = func(value, shuffleXorNV(value, 8, 32)); \
-                                        value = func(value, shuffleXorNV(value, 4, 32)); \
-                                        value = func(value, shuffleXorNV(value, 2, 32)); \
-                                        value = func(value, shuffleXorNV(value, 1, 32));
-#define SUBGROUP_MIN(value) SUBGROUP_REDUCTION(min, value)
-#define SUBGROUP_MAX(value) SUBGROUP_REDUCTION(max, value)
+#define SUPPORTS_SUBGROUP_REDUCTION 1
+#define IS_HELPER_INVOCATION gl_HelperInvocation
+#define IS_FIRST_ACTIVE_INVOCATION (subgroupElect())
+#define SUBGROUP_MIN(value) value = subgroupMin(value)
+#define SUBGROUP_MAX(value) value = subgroupMax(value)
 )";
   }