Merge pull request #9800 from Techjar/vulkan-subgroup-fix

Vulkan: Fix subgroup reduction

Source/Core/VideoBackends/Vulkan/ShaderCompiler.cpp

@@ -103,7 +103,7 @@ static const char SUBGROUP_HELPER_HEADER[] = R"(
   #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(true)))
+  #define IS_FIRST_ACTIVE_INVOCATION (gl_SubgroupInvocationID == subgroupBallotFindLSB(subgroupBallot(!gl_HelperInvocation)))
   #define SUBGROUP_MIN(value) value = subgroupMin(value)
   #define SUBGROUP_MAX(value) value = subgroupMax(value)
 )";