sycl: fuse UNARY(silu|sigmoid|softplus) + MUL (#26411)

Measured on Arc Pro B70 (Battlemage), Qwen3.6-27B Q4_K_M, -fa on, f16 KV,
-b 2048 -ub 2048, llama-bench -r 3, three interleaved A/B rounds:

  pp2048        1014.70 -> 1018.56 t/s   (+0.38%, within run-to-run spread)
  tg128         23.73 -> 23.86 t/s       (+0.57%)
  tg128 @ d4096 22.71 -> 22.86 t/s       (+0.62%)

ggml/src/ggml-sycl/fusion.cpp

@@ -1,6 +1,14 @@
 #include "fusion.hpp"
 
-bool ggml_sycl_can_fuse(const ggml_cgraph * cgraph, int node_idx, std::initializer_list<enum ggml_op> ops) {
+#include <algorithm>
+
+bool ggml_sycl_can_fuse(const ggml_cgraph * cgraph, int node_idx, std::initializer_list<enum ggml_op> ops,
+                        std::initializer_list<enum ggml_unary_op> unary_ops) {
+#ifndef NDEBUG
+    const size_t num_unary = std::count(ops.begin(), ops.end(), GGML_OP_UNARY);
+    GGML_ASSERT(unary_ops.size() == num_unary);
+#endif
+
     if (!g_ggml_sycl_enable_fusion) {
         return false;
     }
@@ -40,5 +48,45 @@ bool ggml_sycl_can_fuse(const ggml_cgraph * cgraph, int node_idx, std::initializ
         return true;
     }
 
+    if (ops.size() == 2 && ops.begin()[0] == GGML_OP_UNARY && ops.begin()[1] == GGML_OP_MUL &&
+        unary_ops.size() == 1) {
+        const ggml_tensor * unary = cgraph->nodes[node_idx];
+        const ggml_tensor * mul   = cgraph->nodes[node_idx + 1];
+
+        const ggml_unary_op unary_op = ggml_get_unary_op(unary);
+        if (unary_op != unary_ops.begin()[0]) {
+            return false;
+        }
+
+        // the ops ggml_sycl_op_unary_mul_fused() has a kernel for
+        if (unary_op != GGML_UNARY_OP_SILU && unary_op != GGML_UNARY_OP_SIGMOID &&
+            unary_op != GGML_UNARY_OP_SOFTPLUS) {
+            return false;
+        }
+
+        if (unary->type != GGML_TYPE_F32 && unary->type != GGML_TYPE_F16) {
+            return false;
+        }
+
+        const ggml_tensor * other = (mul->src[0] == unary) ? mul->src[1] : mul->src[0];
+        if (other->type != unary->type) {
+            return false;
+        }
+
+        // one row stride per source comes from nb[1], so rows must be contiguous and equally
+        // shaped; the destination is written flat, so it must be fully contiguous
+        if (!ggml_is_contiguous_1(unary->src[0]) || !ggml_is_contiguous_1(other) ||
+            !ggml_are_same_shape(other, unary) || !ggml_is_contiguous(mul)) {
+            return false;
+        }
+
+        // the 32-bit fastdiv is inexact past 2^31; decline, the unfused path handles it
+        if (ggml_nelements(mul) >= ((int64_t) 1 << 31)) {
+            return false;
+        }
+
+        return true;
+    }
+
     return false;
 }