// Mechanical adaptation of OA's NCHW AvgPool2d input adjoint.
// Donor: source/cpp/lib/oa/ml/shader/compute/nn/pooling/avgPool2dBwd.slang
import storage;
import attributes;
struct PushConstants {
uint output_gradient_index;
uint input_gradient_index;
uint batch_size;
uint channels;
uint input_height;
uint input_width;
uint output_height;
uint output_width;
uint kernel_size;
uint stride;
uint padding;
};
[[vk::push_constant]] PushConstants push;
[[vk::binding(0, 0)]] RWByteAddressBuffer storage_buffers[];
[kernel_name("avg_pool_2d_backward")]
[domain("ml")]
[variant("generic")]
[dtype("f32")]
[status("experimental")]
[shader("compute")]
[numthreads(16, 16, 1)]
void main(uint3 thread_id : SV_DispatchThreadID) {
uint input_y = thread_id.x;
uint input_x = thread_id.y;
uint batch_channel = thread_id.z;
if (
input_y >= push.input_height
|| input_x >= push.input_width
|| batch_channel >= push.batch_size * push.channels
) {
return;
}
uint batch = batch_channel / push.channels;
uint channel = batch_channel % push.channels;
float gradient_sum = 0.0f;
for (uint output_y = 0; output_y < push.output_height; ++output_y) {
for (uint output_x = 0; output_x < push.output_width; ++output_x) {
int input_y_start = int(output_y * push.stride) - int(push.padding);
int input_x_start = int(output_x * push.stride) - int(push.padding);
int input_y_end = input_y_start + int(push.kernel_size);
int input_x_end = input_x_start + int(push.kernel_size);
if (
int(input_y) >= input_y_start
&& int(input_y) < input_y_end
&& int(input_x) >= input_x_start
&& int(input_x) < input_x_end
) {
uint count = 0;
for (uint kernel_y = 0; kernel_y < push.kernel_size; ++kernel_y) {
for (uint kernel_x = 0; kernel_x < push.kernel_size; ++kernel_x) {
int y = input_y_start + int(kernel_y);
int x = input_x_start + int(kernel_x);
if (
y >= 0
&& y < int(push.input_height)
&& x >= 0
&& x < int(push.input_width)
) {
count += 1;
}
}
}
uint output_offset =
batch * push.channels * push.output_height * push.output_width
+ channel * push.output_height * push.output_width
+ output_y * push.output_width
+ output_x;
gradient_sum += load_f32(
storage_buffers[push.output_gradient_index], output_offset
) / float(count);
}
}
}
uint input_offset =
batch * push.channels * push.input_height * push.input_width
+ channel * push.input_height * push.input_width
+ input_y * push.input_width
+ input_x;
store_f32(storage_buffers[push.input_gradient_index], input_offset, gradient_sum);
}