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, 1 insertions, 2 deletions

diff --git a/Source/Core/VideoBackends/Vulkan/ShaderCompiler.cpp b/Source/Core/VideoBackends/Vulkan/ShaderCompiler.cpp
index 56d20caf43..49b007f43b 100644
--- a/Source/Core/VideoBackends/Vulkan/ShaderCompiler.cpp
+++ b/Source/Core/VideoBackends/Vulkan/ShaderCompiler.cpp
@@ -81,9 +81,8 @@ static const char SUBGROUP_HELPER_HEADER[] = R"(
   #extension GL_KHR_shader_subgroup_ballot : enable
 
   #define SUPPORTS_SUBGROUP_REDUCTION 1
-  #define CAN_USE_SUBGROUP_REDUCTION true
   #define IS_HELPER_INVOCATION gl_HelperInvocation
-  #define IS_FIRST_ACTIVE_INVOCATION (gl_SubgroupInvocationID == subgroupBallotFindLSB(subgroupBallot(!gl_HelperInvocation)))
+  #define IS_FIRST_ACTIVE_INVOCATION (subgroupElect())
   #define SUBGROUP_MIN(value) value = subgroupMin(value)
   #define SUBGROUP_MAX(value) value = subgroupMax(value)
 )";