File size: 2,965 Bytes
48220c7 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 | // Split-K normalize pass. Each workgroup (row = wg.x, split index = wg.z)
// folds the SPLIT per-row partial sums of squares into the RMS scale, then
// normalizes its HIDDEN/SPLIT slice. SPLIT is small (<=64), so the serial fold
// avoids a third combine pass. Scale offsets follow the suffix-axis broadcast
// contract.
{% if usesF16 %}
enable f16;
{% endif %}
{{ env.wgsl.resourceDeclarations }}
const HIDDEN: u32 = {{ hiddenSize }}u;
const EPSILON: f32 = {{ epsilon }};
const WG: u32 = {{ workgroupSize }}u;
const SPLIT: u32 = {{ split }}u;
{% if source.scaleRank > 0 %}
const X_RANK: u32 = {{ source.xRank }}u;
const SCALE_RANK: u32 = {{ source.scaleRank }}u;
const X_SHAPE: array<u32, {{ source.xRank }}> = array<u32, {{ source.xRank }}>({% for d in source.xShape %}{{ d }}u{% if not loop.last %}, {% endif %}{% endfor %});
const SCALE_SHAPE: array<u32, {{ source.scaleRank }}> = array<u32, {{ source.scaleRank }}>({% for d in source.scaleShape %}{{ d }}u{% if not loop.last %}, {% endif %}{% endfor %});
fn x_stride(axis: u32) -> u32 {
var stride = 1u;
for (var i = axis + 1u; i < X_RANK; i += 1u) {
stride *= X_SHAPE[i];
}
return stride;
}
fn scale_stride(axis: u32) -> u32 {
var stride = 1u;
for (var i = axis + 1u; i < SCALE_RANK; i += 1u) {
stride *= SCALE_SHAPE[i];
}
return stride;
}
{% endif %}
fn scale_offset({% if source.scaleRank > 0 %}out_index: u32{% endif %}) -> u32 {
{% if source.scaleRank == 0 %}
return 0u;
{% else %}
var rem = out_index;
var offset = 0u;
for (var axis = 0u; axis < X_RANK; axis += 1u) {
let stride = x_stride(axis);
let coord = rem / stride;
rem %= stride;
let scale_axis = i32(axis) - i32(X_RANK - SCALE_RANK);
if (scale_axis >= 0) {
let s_axis = u32(scale_axis);
if (SCALE_SHAPE[s_axis] != 1u) {
offset += coord * scale_stride(s_axis);
}
}
}
return offset;
{% endif %}
}
@compute @workgroup_size(WG, 1, 1)
fn main(@builtin(workgroup_id) wg: vec3<u32>, @builtin(local_invocation_id) lid: vec3<u32>) {
let row = wg.x + wg.y * params.rowStride;
if (row >= params.rows) {
return;
}
let k = wg.z;
let tid = lid.x;
var total = 0.0;
for (var i = 0u; i < SPLIT; i = i + 1u) {
total = total + partials[row * SPLIT + i];
}
let inv = inverseSqrt(total / f32(HIDDEN) + EPSILON);
{% if source.writeStats %}
// Every split workgroup folds the same partials, so one designated
// workgroup writes the row statistic.
if (k == 0u && tid == 0u) {
inv_std_out[row] = inv;
}
{% endif %}
let chunk = (HIDDEN + SPLIT - 1u) / SPLIT;
let start = k * chunk;
var end = start + chunk;
if (end > HIDDEN) { end = HIDDEN; }
let base = row * HIDDEN;
var d = start + tid;
loop {
if (d >= end) { break; }
let index = base + d;
let value = f32(x[index]) * inv * f32(scale[scale_offset({% if source.scaleRank > 0 %}index{% endif %})]);
y[index] = {{ scalar }}(value);
d = d + WG;
}
}
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