reshape_2d used from ddim.h

test=develop

paddle/fluid/framework/ir/conv_bn_fuse_pass.cc

@@ -44,18 +44,6 @@ namespace ir {
   GET_IR_NODE_FROM_SUBGRAPH(bn_saved_mean, bn_saved_mean, pattern_name);     \
   GET_IR_NODE_FROM_SUBGRAPH(bn_saved_variance, bn_saved_variance, pattern_name)
 
-// reshape to two dimensions {A, B * C * ...}
-DDim make_dims_2d(DDim dims) {
-  auto dims_count = dims.size();
-  PADDLE_ENFORCE_GT(dims_count, 0);
-
-  int size2 = 1;
-  for (int i = 1; i < dims_count; i++) {
-    size2 *= dims[i];
-  }
-  return make_ddim({dims[0], size2});
-}
-
 void recompute_bias_and_weights(const Scope* scope,
                                 ir::Node* conv_weight,            //
                                 const ir::Node& bn_scale,         //
@@ -104,7 +92,7 @@ void recompute_bias_and_weights(const Scope* scope,
   // Re-compute weight of conv2d from BN
   auto* weights = scope->FindVar(conv_weight->Name())->GetMutable<LoDTensor>();
   auto weights_shape = weights->dims();
-  auto weights_shape_2d = make_dims_2d(weights_shape);
+  auto weights_shape_2d = flatten_to_2d(weights_shape, 1);
 
   EigenMatrixArrayMap weights_array_2d(
       weights->mutable_data<float>(platform::CPUPlace()), weights_shape_2d[0],