Performance fix for broadcast kernel [Part3] (#45854)

* first commit

* fix some bugs in code

* fix bugs

* to optimize merge one dimension feature

paddle/phi/kernels/funcs/broadcast_function.h

@@ -213,9 +213,10 @@ struct DimensionsTransform {
         }
       }
     };
-    int swap_idx = 0;
-    bool has_seq_one = FindSequentialOneDim(&swap_idx);
-    if (has_seq_one) {
+    for (auto i = 0; i < dim_size; ++i) {
+      int swap_idx = 0;
+      bool has_seq_one = FindSequentialOneDim(&swap_idx);
+      if (!has_seq_one) break;
       merge_ptr = merge_sequential_one_dims;
       MergeDimensions<MergeFunctor>(merge_ptr, N);
       std::swap(in_dims[swap_idx], in_dims[0]);
@@ -508,7 +509,6 @@ void BroadcastKernelForDifferentVecSize(
                                    "functions is %d.",
                                    outs->size(),
                                    NumOuts));
-
   // mergedim and get vec_size
   const auto merge_dims = DimensionsTransform(ins, (*outs)[0]->dims(), axis);
   phi::Array<kps::details::BroadcastConfig, kArity> configs;

paddle/phi/kernels/primitive/datamover_primitives.h

@@ -85,7 +85,7 @@ struct FastDivMod {
 struct BroadcastConfig {
   FastDivMod divmoders[phi::DDim::kMaxRank];
   uint32_t strides[phi::DDim::kMaxRank];
-  int kDims;
+  int kDims{0};
   HOSTDEVICE BroadcastConfig() {}
 
   HOSTDEVICE BroadcastConfig(const std::vector<int64_t>& out_dims,