ryujinx/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/ShuffleUp.glsl

float Helper_ShuffleUp(float x, uint index, uint mask)
{
    uint clamp = mask & 0x1fu;
    uint segMask = (mask >> 8) & 0x1fu;
    uint minThreadId = gl_SubGroupInvocationARB & segMask;
    uint srcThreadId = gl_SubGroupInvocationARB - index;
    return (srcThreadId >= minThreadId) ? readInvocationARB(x, srcThreadId) : x;
}