opencl: fold the gpt-oss MoE per-expert bias adds into the epilogue (op/kernel fusion) (#26431)

* opencl: fold the gpt-oss MoE bias adds into swiglu_oai Default on, opt out with GGML_OPENCL_FUSE_MOE_BIAS_GLU=0. * opencl: fold the MoE down-projection bias into the combine Default on, opt out with GGML_OPENCL_FUSE_MOE_BIAS_COMBINE=0.
2026-08-21 14:24:33 -07:00
parent 9a286ac98d
commit 3af988fabc
4 changed files with 473 additions and 0 deletions
@@ -8,6 +8,49 @@
 // buffer and the k-1 elementwise add round-trips). Vectorized float4 over rows.
 // strides e1/e2/w1/w2/d1 are in ELEMENTS (floats).

+// Same weighted sum, with the per-expert bias add folded in.
+//
+// The MoE down projection's bias is applied by an in-place add_id whose only
+// consumer is this combine, so it costs a full read plus a full write of a
+// tensor that is read once more immediately afterwards. Reading the raw matmul
+// output here and adding the bias row while it is already in registers removes
+// that pass. Kept as a separate kernel so the unfused path is untouched.
+__kernel void kernel_moe_combine_bias_f32(
+        __global const char * e_buf, ulong off_e,
+        __global const char * w_buf, ulong off_w,
+        __global const char * b_buf, ulong off_b,   // per-expert bias rows
+        __global const char * i_buf, ulong off_i,   // expert ids
+        __global       char * d_buf, ulong off_d,
+        int  n_embd4,            // n_embd / 4
+        int  k,                  // n_expert_used
+        int  n_tokens,
+        uint e1, uint e2,        // experts strides (elements): per-expert, per-token
+        uint w1, uint w2,        // weights strides (elements)
+        uint d1,                 // dst per-token stride (elements)
+        ulong nb_b1,             // bias row stride (bytes)
+        ulong nb_i1)             // ids row stride (bytes) - ids is a view, not packed
+{
+    const uint r4  = get_global_id(0);
+    const uint tok = get_global_id(1);
+    if (r4 >= (uint)n_embd4 || tok >= (uint)n_tokens) return;
+
+    __global const float * E = (__global const float *)(e_buf + off_e) + tok*e2 + r4*4u;
+    __global const float * W = (__global const float *)(w_buf + off_w) + tok*w2;
+    __global const char  * B = b_buf + off_b;
+    __global const char  * I = i_buf + off_i + (ulong)tok*nb_i1;
+
+    float4 acc = (float4)(0.0f);
+    for (int e = 0; e < k; ++e) {
+        const int i11 = *((__global const int *)(I + (ulong)e*sizeof(int)));
+        __global const float * Brow = (__global const float *)(B + (ulong)i11*nb_b1) + r4*4u;
+        const float4 v = vload4(0, E + (uint)e*e1) + vload4(0, Brow);
+        acc = mad(v, (float4)(W[(uint)e*w1]), acc);
+    }
+
+    __global float * D = (__global float *)(d_buf + off_d) + tok*d1 + r4*4u;
+    vstore4(acc, 0, D);
+}
+
 __kernel void kernel_moe_combine_f32(
        __global const char * e_buf, ulong off_e,
        __global const char * w_buf, ulong off_w,