use super::{NormalizationError, rms};
use ruda_core::{device::Device, ir::features::Plane, tensor::{DType, Shape}};
use ruda_kernel::{
dsl::{Runtime, calculate_ruda_count_elemwise, prelude::*},
tensor::{RudaTensor, allocation::empty_device_contiguous_dtype, contiguous::into_contiguous},
};
fn layout<R: Runtime>(input: &RudaTensor<R>) -> Result<(usize, usize, u32, bool), NormalizationError> {
let width = *input.meta.shape().last().ok_or(NormalizationError("RMSNorm requires an axis"))?;
let elements = input.meta.shape().iter().try_fold(1usize, |n, &extent| n.checked_mul(extent));
if width == 0 || width > u32::MAX as usize || elements.is_none_or(|size| size > u32::MAX as usize)
|| !matches!(input.dtype, DType::F32 | DType::F16 | DType::BF16) || input.qparams.is_some() {
return Err(NormalizationError("invalid RMSNorm training shape or storage"));
}
let rows = elements.unwrap() / width;
let properties = input.client.properties();
let hardware = &properties.hardware;
let maximum = hardware.max_ruda_dim.0.min(hardware.max_units_per_ruda);
let plane = hardware.plane_size_max;
if !properties.features.plane.contains(Plane::Ops) || !plane.is_power_of_two()
|| plane > maximum || rows > hardware.max_ruda_count.0 as usize {
return Err(NormalizationError("RMSNorm runtime cannot launch row reductions"));
}
let (threads, vectorized) = rms::launch_parameters(width, rows, plane, maximum);
Ok((rows, width, threads, vectorized))
}
fn binding<R: Runtime>(input: &RudaTensor<R>, value: &RudaTensor<R>) -> Result<(), NormalizationError> {
if value.qparams.is_some() || value.device.to_id() != input.device.to_id()
|| !input.client.same_execution_queue(&value.client) {
return Err(NormalizationError("RMSNorm training bindings must share their execution queue and device"));
}
Ok(())
}
fn weight<R: Runtime>(input: &RudaTensor<R>, gamma: &RudaTensor<R>, width: usize) -> Result<(), NormalizationError> {
binding(input, gamma)?;
if gamma.meta.shape()[..] != [width] || !matches!(gamma.dtype, DType::F32 | DType::F16 | DType::BF16) {
return Err(NormalizationError("RMSNorm weight must be a floating feature vector"));
}
Ok(())
}
pub fn rms_norm_with_stats<R: Runtime>(input: RudaTensor<R>, gamma: RudaTensor<R>, epsilon: f32)
-> Result<[RudaTensor<R>; 2], NormalizationError> {
let (rows, width, threads, vectorized) = layout(&input)?;
weight(&input, &gamma, width)?;
if !epsilon.is_finite() || epsilon <= 0.0 { return Err(NormalizationError("invalid RMSNorm epsilon")); }
let output = empty_device_contiguous_dtype(input.client.clone(), input.device.clone(), input.meta.shape().clone(), input.dtype);
let rstd = empty_device_contiguous_dtype(input.client.clone(), input.device.clone(), Shape::new([rows]), DType::F32);
if rows > 0 {
let types = [input.dtype.into(), gamma.dtype.into()];
rms::training_forward::launch(&output.client, RudaCount::Static(rows as u32, 1, 1), RudaDim::new_1d(threads),
into_contiguous(input).into_array_arg(), into_contiguous(gamma).into_array_arg(),
output.clone().into_array_arg(), rstd.clone().into_array_arg(), width as u32, epsilon,
threads, vectorized, types);
}
Ok([output, rstd])
}
pub fn rms_norm_backward<R: Runtime>(input: RudaTensor<R>, gamma: RudaTensor<R>, grad: RudaTensor<R>, rstd: RudaTensor<R>)
-> Result<[RudaTensor<R>; 2], NormalizationError> {
let (rows, width, threads) = backward_layout(&input, &gamma, &grad, &rstd)?;
let input_grad = empty_device_contiguous_dtype(input.client.clone(), input.device.clone(), input.meta.shape().clone(), input.dtype);
let weight_grad = empty_device_contiguous_dtype(input.client.clone(), input.device.clone(), Shape::new([width]), gamma.dtype);
let input = into_contiguous(input);
let gamma = into_contiguous(gamma);
let grad = into_contiguous(grad);
let rstd = into_contiguous(rstd);
let client = input.client.clone();
if rows > 0 {
rms::input_backward::launch(&client, RudaCount::Static(rows as u32, 1, 1), RudaDim::new_1d(threads),
input.clone().into_array_arg(), gamma.clone().into_array_arg(), grad.clone().into_array_arg(),
rstd.clone().into_array_arg(), input_grad.clone().into_array_arg(), width as u32, threads,
[input.dtype.into(), gamma.dtype.into(), grad.dtype.into()]);
}
let parts = rows.div_ceil(32).clamp(1, 128);
let work = parts * width;
let partial = empty_device_contiguous_dtype(client.clone(), input.device.clone(), Shape::new([parts, width]), DType::F32);
let part_dim = RudaDim::new(client.properties(), work);
let part_count = calculate_ruda_count_elemwise(&client, work, part_dim);
rms::weight_partial::launch(&client, part_count, part_dim, input.clone().into_array_arg(), grad.clone().into_array_arg(),
rstd.into_array_arg(), partial.clone().into_array_arg(), width as u32, parts as u32,
[input.dtype.into(), grad.dtype.into()]);
let merge_dim = RudaDim::new(client.properties(), width);
let merge_count = calculate_ruda_count_elemwise(&client, width, merge_dim);
rms::weight_merge::launch(&client, merge_count, merge_dim, partial.into_array_arg(), weight_grad.clone().into_array_arg(),
parts as u32, gamma.dtype.into());
Ok([input_grad, weight_grad])
}
fn backward_layout<R: Runtime>(input: &RudaTensor<R>, gamma: &RudaTensor<R>, grad: &RudaTensor<R>, rstd: &RudaTensor<R>)
-> Result<(usize, usize, u32), NormalizationError> {
let (rows, width, threads, _) = layout(input)?;
weight(input, gamma, width)?;
for value in [grad, rstd] { binding(input, value)?; }
if grad.meta.shape() != input.meta.shape() || !matches!(grad.dtype, DType::F32 | DType::F16 | DType::BF16)
|| rstd.dtype != DType::F32 || rstd.meta.shape()[..] != [rows] {
return Err(NormalizationError("invalid RMSNorm gradient or saved statistics"));
}
Ok((rows, width, threads))
}
pub fn rms_norm_backward_select<R: Runtime>(input: RudaTensor<R>, gamma: RudaTensor<R>, grad: RudaTensor<R>,
rstd: RudaTensor<R>, mask: [bool; 2]) -> Result<[Option<RudaTensor<R>>; 2], NormalizationError> {
if mask == [false; 2] { return Ok([None, None]); }
if mask == [true; 2] { return Ok(rms_norm_backward(input, gamma, grad, rstd)?.map(Some)); }
let (rows, width, threads) = backward_layout(&input, &gamma, &grad, &rstd)?;
let allocate = |shape, dtype| empty_device_contiguous_dtype(input.client.clone(), input.device.clone(), shape, dtype);
let input_grad = mask[0].then(|| allocate(input.meta.shape().clone(), input.dtype));
let weight_grad = mask[1].then(|| allocate(Shape::new([width]), gamma.dtype));
let input = into_contiguous(input);
let gamma = if mask[0] { into_contiguous(gamma) } else { gamma };
let grad = into_contiguous(grad);
let rstd = into_contiguous(rstd);
let client = input.client.clone();
if let Some(output) = &input_grad {
if rows > 0 {
rms::input_backward::launch(&client, RudaCount::Static(rows as u32, 1, 1), RudaDim::new_1d(threads),
input.clone().into_array_arg(), gamma.clone().into_array_arg(), grad.clone().into_array_arg(),
rstd.clone().into_array_arg(), output.clone().into_array_arg(), width as u32, threads,
[input.dtype.into(), gamma.dtype.into(), grad.dtype.into()]);
}
}
if let Some(output) = &weight_grad {
let parts = rows.div_ceil(32).clamp(1, 128);
let work = parts * width;
let partial = empty_device_contiguous_dtype(client.clone(), input.device.clone(), Shape::new([parts, width]), DType::F32);
let dim = RudaDim::new(client.properties(), work);
let count = calculate_ruda_count_elemwise(&client, work, dim);
rms::weight_partial::launch(&client, count, dim, input.clone().into_array_arg(), grad.clone().into_array_arg(),
rstd.into_array_arg(), partial.clone().into_array_arg(), width as u32, parts as u32,
[input.dtype.into(), grad.dtype.into()]);
let dim = RudaDim::new(client.properties(), width);
let count = calculate_ruda_count_elemwise(&client, width, dim);
rms::weight_merge::launch(&client, count, dim, partial.into_array_arg(), output.clone().into_array_arg(),
parts as u32, gamma.dtype.into());
}
Ok([input_grad, weight_grad])
}