fix: revert layernorm(cpu)

Author: futz12

src/layer/layernorm.cpp

@@ -88,7 +88,8 @@ int LayerNorm::forward_inplace(Mat& bottom_top_blob, const Option& opt) const
         float* ptr = bottom_top_blob;
         layernorm(ptr, gamma_data, beta_data, eps, w);
     }
-    else if (dims == 2)
+
+    if (dims == 2)
     {
         int w = bottom_top_blob.w;
         int h = bottom_top_blob.h;
@@ -101,35 +102,32 @@ int LayerNorm::forward_inplace(Mat& bottom_top_blob, const Option& opt) const
             layernorm(ptr, gamma_data, beta_data, eps, w);
         }
     }
-    else if (dims == 3)
+
+    if (dims == 3)
     {
         int w = bottom_top_blob.w;
         int h = bottom_top_blob.h;
         int channels = bottom_top_blob.c;
 
-        int group_size;
-        int num_groups_per_channel;
-
         if (affine_size == w)
         {
-            group_size = w;
-            num_groups_per_channel = h;
-        }
-        else // if (affine_size == w * h)
-        {
-            group_size = w * h;
-            num_groups_per_channel = 1;
+            #pragma omp parallel for num_threads(opt.num_threads)
+            for (int q = 0; q < channels; q++)
+            {
+                for (int i = 0; i < h; i++)
+                {
+                    float* ptr = bottom_top_blob.channel(q).row(i);
+                    layernorm(ptr, gamma_data, beta_data, eps, w);
+                }
+            }
         }
-
-        #pragma omp parallel for num_threads(opt.num_threads)
-        for (int q = 0; q < channels; q++)
+        else // if (affine_size == size)
         {
-            float* channel_ptr = bottom_top_blob.channel(q);
-
-            for (int i = 0; i < num_groups_per_channel; i++)
+            #pragma omp parallel for num_threads(opt.num_threads)
+            for (int q = 0; q < channels; q++)
             {
-                float* ptr = channel_ptr + i * group_size;
-                layernorm(ptr, gamma_data, beta_data, eps, group_size);
+                float* ptr = bottom_top_blob.channel(q);
+                layernorm(ptr, gamma_data, beta_data, eps, w * h);
             }
         }
     }

src/layer/layernorm.h

@@ -32,4 +32,4 @@ class LayerNorm : public Layer
 
 } // namespace ncnn
 
-#endif // LAYER_LAYERNORM_H
+#endif // LAYER_LAYERNORM_H