ggml-webgpu: Add fused RMS_NORM + MUL (#21983)

* fused rms_norm_mul + mul * Add GGML_WEBGPU_DISABLE_FUSION for being able to disable kernel fusion. * Decouple num_fused_ops from webgpu_context; misc cleanup * Fix eps handling and remove disable_fusion. * Fix not to use c++20 initializers.
2026-04-22 10:51:40 -07:00
parent 8bccdbbff9
commit 6da7168312
3 changed files with 349 additions and 18 deletions
@@ -0,0 +1,139 @@
+#ifdef INPLACE
+
+@group(0) @binding(0)
+var<storage, read_write> rn_src: array<f32>;
+
+@group(0) @binding(1)
+var<storage, read_write> mul_src: array<f32>;
+
+@group(0) @binding(2)
+var<uniform> params: Params;
+
+fn update(rn_src_offset: u32, dst_offset: u32, scale: f32, mul_src_offset: u32) {
+    mul_src[dst_offset] = scale * rn_src[rn_src_offset] * mul_src[mul_src_offset];
+}
+
+#elif SRC_OVERLAP
+
+@group(0) @binding(0)
+var<storage, read_write> merged_src: array<f32>;
+
+@group(0) @binding(1)
+var<storage, read_write> dst: array<f32>;
+
+@group(0) @binding(2)
+var<uniform> params: Params;
+
+fn update(rn_src_offset: u32, dst_offset: u32, scale: f32, mul_src_offset: u32) {
+    dst[dst_offset] = scale * merged_src[rn_src_offset] * merged_src[mul_src_offset];
+}
+
+#else
+
+@group(0) @binding(0)
+var<storage, read_write> rn_src: array<f32>;
+
+@group(0) @binding(1)
+var<storage, read_write> mul_src: array<f32>;
+
+@group(0) @binding(2)
+var<storage, read_write> dst: array<f32>;
+
+@group(0) @binding(3)
+var<uniform> params: Params;
+
+fn update(rn_src_offset: u32, dst_offset: u32, scale: f32, mul_src_offset: u32) {
+    dst[dst_offset] = scale * rn_src[rn_src_offset] * mul_src[mul_src_offset];
+}
+
+#endif
+
+struct Params {
+    offset_rn_src: u32,
+    offset_mul_src: u32,
+    offset_merged_rn_src: u32,
+    offset_merged_mul_src: u32,
+    offset_dst: u32,
+
+    stride_rn_src1: u32,
+    stride_rn_src2: u32,
+    stride_rn_src3: u32,
+
+    stride_mul_src1: u32,
+    stride_mul_src2: u32,
+    stride_mul_src3: u32,
+
+    stride_dst1: u32,
+    stride_dst2: u32,
+    stride_dst3: u32,
+
+    mul_src_ne0: u32,
+    mul_src_ne1: u32,
+    mul_src_ne2: u32,
+    mul_src_ne3: u32,
+
+    ne0: u32,
+    ne1: u32,
+    ne2: u32,
+    ne3: u32,
+
+    eps: f32
+};
+
+var<workgroup> scratch: array<f32, WG_SIZE>;
+
+@compute @workgroup_size(WG_SIZE)
+fn main(@builtin(workgroup_id) wid: vec3<u32>,
+        @builtin(local_invocation_id) lid: vec3<u32>) {
+
+    // one thread per row
+    var i = wid.x;
+    let i3 = i / (params.ne2 * params.ne1);
+    i = i % (params.ne2 * params.ne1);
+    let i2 = i / params.ne1;
+    let i1 = i % params.ne1;
+    let i_rn_src_row = params.offset_rn_src + params.offset_merged_rn_src + i3 * params.stride_rn_src3 + i2 * params.stride_rn_src2 + i1 * params.stride_rn_src1;
+    let i_mul_src_row = params.offset_mul_src + params.offset_merged_mul_src + (i3 % params.mul_src_ne3) * params.stride_mul_src3 + (i2 % params.mul_src_ne2) * params.stride_mul_src2 + (i1 % params.mul_src_ne1) * params.stride_mul_src1;
+    let i_dst_row = params.offset_dst + i3 * params.stride_dst3 + i2 * params.stride_dst2 + i1 * params.stride_dst1;
+
+    let elems = (params.ne0 + WG_SIZE - 1) / WG_SIZE;
+
+    var sum = 0.0f;
+    var col = lid.x;
+    for (var j: u32 = 0; j < elems; j++) {
+        if (col >= params.ne0) {
+            break;
+        }
+#ifdef SRC_OVERLAP
+        sum += pow(merged_src[i_rn_src_row + col], 2.0);
+#else
+        sum += pow(rn_src[i_rn_src_row + col], 2.0);
+#endif
+        col += WG_SIZE;
+    }
+
+    scratch[lid.x] = sum;
+
+    workgroupBarrier();
+
+    var offset: u32 = WG_SIZE / 2;
+    while (offset > 0) {
+        if (lid.x < offset) {
+            scratch[lid.x] += scratch[lid.x + offset];
+        }
+        offset = offset / 2;
+        workgroupBarrier();
+    }
+    sum = scratch[0];
+
+    let scale = 1.0/sqrt(sum/f32(params.ne0) + params.eps);
+
+    col = lid.x;
+    for (var j: u32 = 0; j < elems; j++) {
+        if (col >= params.ne0) {
+            break;
+        }
+        update(i_rn_src_row + col, i_dst_row + col, scale, i_mul_src_row + col % params.mul_src_ne0);
+        col += WG_SIZE;
+    }
+}