softmax.comp
2.13 KB
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#version 450
#define LOCAL_SZ_X 256
layout(binding = 0) readonly buffer buf0{
float input_buffer[]; // outer_size * channels * channel_size
};
layout(binding = 1) buffer buf1{
float max_buffer[]; // outer_size * channel_size
};
layout(binding = 2) buffer buf2{
float sum_buffer[]; // outer_size * channel_size
};
layout(binding = 3) buffer buf3{
float output_buffer[]; // outer_size * channels * channel_size
};
layout(push_constant) uniform pushBlock {
int channel_size;
int outer_size;
int channels;
int logsoftmax;
} p;
layout(local_size_x = LOCAL_SZ_X, local_size_y = 1, local_size_z = 1) in;
void main()
{
int gid = int(gl_GlobalInvocationID.x);
if (gid >= p.outer_size) return;
int global_off = gid * p.channels * p.channel_size;
int reduced_buffer_off = gid * p.channel_size;
// find the max along channel
int index = global_off;
for (int i = 0; i < p.channel_size; ++i)
{
max_buffer[reduced_buffer_off + i] = input_buffer[index];
index++;
}
for (int c = 1; c < p.channels; ++c)
{
for (int i = 0; i < p.channel_size; ++i)
{
max_buffer[reduced_buffer_off + i] = max(max_buffer[reduced_buffer_off + i], input_buffer[index]);
index++;
}
}
// subtract, exp and accumulate along channel
for (int i = 0; i < p.channel_size; ++i)
sum_buffer[reduced_buffer_off + i] = 0.f;
index = global_off;
for (int c = 0; c < p.channels; ++c)
{
for (int i = 0; i < p.channel_size; ++i)
{
float exp_val = exp(input_buffer[index] - max_buffer[reduced_buffer_off + i]);
output_buffer[index] = exp_val;
sum_buffer[reduced_buffer_off + i] += exp_val;
index++;
}
}
// divide by computed sum
index = global_off;
for (int c = 0; c < p.channels; ++c)
{
for (int i = 0; i < p.channel_size; ++i)
{
float v = output_buffer[index] / sum_buffer[reduced_buffer_off + i];
if (p.logsoftmax == 1)
v = log(v);
output_buffer[index] = v;
index++;
}
}
}