#version 450
#include "generic_head.glsl"
#include "types.glsl"
#extension GL_EXT_control_flow_attributes : enable
layout(constant_id = 0) const uint BLOCK_SIZE = 32;
layout(local_size_x_id = 0, local_size_y = 1, local_size_z = 1) in;
layout (binding = 0) readonly buffer G {A_TYPE data_g[];};
layout (binding = 1) readonly buffer X {B_TYPE data_x[];};
layout (binding = 2) readonly buffer Y {B_TYPE data_y[];};
layout (binding = 3) writeonly buffer D {D_TYPE data_d[];};
shared FLOAT_TYPE tmp[BLOCK_SIZE];
FLOAT_TYPE wg_reduce_max(FLOAT_TYPE v) {
const uint tid = gl_LocalInvocationID.x;
tmp[tid] = v;
barrier();
[[unroll]] for (uint s = BLOCK_SIZE / 2; s > 0; s >>= 1) {
if (tid < s) {
tmp[tid] = max(tmp[tid], tmp[tid + s]);
}
barrier();
}
v = tmp[0];
barrier();
return v;
}
FLOAT_TYPE wg_reduce_sum(FLOAT_TYPE v) {
const uint tid = gl_LocalInvocationID.x;
tmp[tid] = v;
barrier();
[[unroll]] for (uint s = BLOCK_SIZE / 2; s > 0; s >>= 1) {
if (tid < s) {
tmp[tid] += tmp[tid + s];
}
barrier();
}
v = tmp[0];
barrier();
return v;
}
void main() {
const uint row = gl_WorkGroupID.z * 262144 + gl_WorkGroupID.y * 512 + gl_WorkGroupID.x;
const uint tid = gl_LocalInvocationID.x;
if (row >= p.KY) {
return;
}
const uint off = row * p.KX;
const FLOAT_TYPE d_by_nrows = FLOAT_TYPE(data_g[0]) / FLOAT_TYPE(p.KY);
FLOAT_TYPE max_logit = FLOAT_TYPE(uintBitsToFloat(0xFF800000));
for (uint i = tid; i < p.KX; i += BLOCK_SIZE) {
max_logit = max(max_logit, FLOAT_TYPE(data_x[off + i]));
}
max_logit = wg_reduce_max(max_logit);
FLOAT_TYPE sum_exp = FLOAT_TYPE(0.0f);
for (uint i = tid; i < p.KX; i += BLOCK_SIZE) {
sum_exp += exp(FLOAT_TYPE(data_x[off + i]) - max_logit);
}
const FLOAT_TYPE inv_sum = FLOAT_TYPE(1.0f) / wg_reduce_sum(sum_exp);
for (uint i = tid; i < p.KX; i += BLOCK_SIZE) {
const FLOAT_TYPE sm = exp(FLOAT_TYPE(data_x[off + i]) - max_logit) * inv_sum;
data_d[off + i] = D_TYPE((sm - FLOAT_TYPE(data_y[off + i])) * d_by_nrows);
}
}