[Neuron] Add custom_ops for neuron backend (#13246)

Signed-off-by: Liangfu Chen <liangfc@amazon.com>
Co-authored-by: George Novack <gnovack@amazon.com>
Co-authored-by: Aoyu Zhang <aoyuzhan@amazon.com>

vllm/model_executor/layers/activation.py

@@ -89,6 +89,13 @@ class SiluAndMul(CustomOp):
         self.op(out, x)
         return out
 
+    def forward_neuron(self, x: torch.Tensor) -> torch.Tensor:
+        d = x.shape[-1] // 2
+        x_reshaped = x.view(-1, x.shape[-1])
+        s = x_reshaped[:, :d] * F.sigmoid(x_reshaped[:, :d])
+        result = s * x_reshaped[:, d:]
+        return result.view(*x.shape[:-1], d)
+
 
 @CustomOp.register("mul_and_silu")
 class MulAndSilu(CustomOp):