diff --git a/paddle/fluid/framework/ddim.cc b/paddle/fluid/framework/ddim.cc
index 3640138e18059a99607111e91b204907f6d551ba..f7fee04c1e2730674f0b8e24470b53a33294717f 100644
--- a/paddle/fluid/framework/ddim.cc
+++ b/paddle/fluid/framework/ddim.cc
@@ -18,32 +18,10 @@ limitations under the License. */
 namespace paddle {
 namespace framework {
 
-template <typename T>
-struct DDimAssignFunctor {
-  static_assert(std::is_integral<T>::value, "T must be integral type");
-  using result_type = void;
-  explicit DDimAssignFunctor(const T* in) : in_(in) {}
-
-  template <int D>
-  inline void operator()(Dim<D>& dim) {  // NOLINT
-    UnrollAssign<D>::Run(in_, dim.data());
-  }
-
-  const T* in_;
-};
-
-DDim::DDim(const int* d, int n) : rank_(n) {
-  this->apply_visitor(DDimAssignFunctor<int>(d));
-}
-
-DDim::DDim(const int64_t* d, int n) : rank_(n) {
-  this->apply_visitor(DDimAssignFunctor<int64_t>(d));
-}
-
 template <int N>
 Dim<N> make_dim(const int64_t* d) {
   Dim<N> ret;
-  for (int i = 0; i < N; ++i) ret[i] = d[i];
+  fix_dim_assign(d, ret.GetMutable());
   return ret;
 }
 
@@ -64,14 +42,14 @@ struct DDimEqualityVisitor {
 
   template <int D>
   inline bool operator()(const Dim<D>& self) const {
-    return UnrollCompare<D>::Run(self.data(), d_);
+    return UnrollCompare<D>::Run(self.Get(), d_);
   }
 
   const int64_t* d_;
 };
 
 bool DDim::operator==(const DDim& d) const {
-  return rank_ == d.rank_ && this->apply_visitor(DDimEqualityVisitor(d.data()));
+  return rank_ == d.rank_ && this->apply_visitor(DDimEqualityVisitor(d.Get()));
 }
 
 bool DDim::operator!=(const DDim& d) const { return !(*this == d); }
@@ -82,7 +60,7 @@ struct DDimPlusVisitor {
 
   template <int D>
   inline void operator()(Dim<D>& self) const {
-    UnrollAdd<D>::Run(d1_, d2_, self.data());
+    UnrollAdd<D>::Run(d1_, d2_, self.GetMutable());
   }
 
   const int64_t* d1_;
@@ -93,7 +71,7 @@ DDim DDim::operator+(const DDim& d) const {
   PADDLE_ENFORCE(rank_ == d.rank_);
   DDim ret;
   ret.rank_ = rank_;
-  ret.apply_visitor(DDimPlusVisitor(data(), d.data()));
+  ret.apply_visitor(DDimPlusVisitor(Get(), d.Get()));
   return ret;
 }
 
@@ -103,7 +81,7 @@ struct DDimMulVisitor {
 
   template <int D>
   inline void operator()(Dim<D>& self) const {
-    UnrollMul<D>::Run(d1_, d2_, self.data());
+    UnrollMul<D>::Run(d1_, d2_, self.GetMutable());
   }
 
   const int64_t* d1_;
@@ -114,7 +92,7 @@ DDim DDim::operator*(const DDim& d) const {
   PADDLE_ENFORCE(rank_ == d.rank_);
   DDim ret;
   ret.rank_ = rank_;
-  ret.apply_visitor(DDimMulVisitor(data(), d.data()));
+  ret.apply_visitor(DDimMulVisitor(Get(), d.Get()));
   return ret;
 }
 
@@ -124,9 +102,7 @@ void set(DDim& ddim, int idx, int value) { ddim[idx] = value; }  // NOLINT
 
 std::vector<int64_t> vectorize(const DDim& ddim) {
   std::vector<int64_t> result(DDim::kMaxRank);
-  for (int i = 0; i < ddim.size(); ++i) {
-    result[i] = ddim[i];
-  }
+  dynamic_dim_assign(ddim.Get(), result.data(), ddim.size());
   result.resize(ddim.size());
   return result;
 }
@@ -135,9 +111,7 @@ std::vector<int64_t> vectorize(const DDim& ddim) {
 //       which does not fit cudnn inputs.
 std::vector<int> vectorize2int(const DDim& ddim) {
   std::vector<int> result(DDim::kMaxRank);
-  for (int i = 0; i < ddim.size(); ++i) {
-    result[i] = ddim[i];
-  }
+  dynamic_dim_assign(ddim.Get(), result.data(), ddim.size());
   result.resize(ddim.size());
   return result;
 }
@@ -154,15 +128,11 @@ int64_t product(const DDim& ddim) {
 }
 
 DDim slice_ddim(const DDim& dim, int begin, int end) {
-  PADDLE_ENFORCE(begin < end,
-                 "Begin index must be less than end index in ddim slice.");
   PADDLE_ENFORCE(begin >= 0,
                  "Begin index can't be less than zero in ddim slice.");
   DDim ret;
   ret.rank_ = end - begin;
-  for (int i = 0; i < ret.rank_; ++i) {
-    ret[i] = dim[i + begin];
-  }
+  dynamic_dim_assign(dim.Get() + begin, ret.GetMutable(), ret.rank_);
   return ret;
 }
 
diff --git a/paddle/fluid/framework/ddim.h b/paddle/fluid/framework/ddim.h
index bff710040eba29f553440417fd0701b2555e8467..e65d451cdef11a7bd571d91483808a008308845f 100644
--- a/paddle/fluid/framework/ddim.h
+++ b/paddle/fluid/framework/ddim.h
@@ -22,6 +22,29 @@ limitations under the License. */
 namespace paddle {
 namespace framework {
 
+template <typename T1, typename T2>
+inline void dynamic_dim_assign(const T1* in, T2* out, int n) {
+#define STATIC_DIM_ASSIGN_CASE(rank)          \
+  case rank:                                  \
+    static_dim_assign<rank, T1, T2>(in, out); \
+    return
+  switch (n) {
+    STATIC_DIM_ASSIGN_CASE(0);
+    STATIC_DIM_ASSIGN_CASE(1);
+    STATIC_DIM_ASSIGN_CASE(2);
+    STATIC_DIM_ASSIGN_CASE(3);
+    STATIC_DIM_ASSIGN_CASE(4);
+    STATIC_DIM_ASSIGN_CASE(5);
+    STATIC_DIM_ASSIGN_CASE(6);
+    STATIC_DIM_ASSIGN_CASE(7);
+    STATIC_DIM_ASSIGN_CASE(8);
+    STATIC_DIM_ASSIGN_CASE(9);
+    default:
+      PADDLE_THROW("Invalid rank %d", n);
+  }
+#undef STATIC_DIM_ASSIGN_CASE
+}
+
 /**
  * \brief A dynamically sized dimension.
  *
@@ -33,8 +56,13 @@ class DDim {
 
   DDim() : rank_(1) { dim_[0] = 0; }
 
-  DDim(const int* d, int n);
-  DDim(const int64_t* d, int n);
+  DDim(const int* d, int n) : rank_(n) {
+    dynamic_dim_assign(d, dim_.GetMutable(), n);
+  }
+
+  DDim(const int64_t* d, int n) : rank_(n) {
+    dynamic_dim_assign(d, dim_.GetMutable(), n);
+  }
 
   template <int D>
   /*implicit*/ DDim(const Dim<D>& in) : rank_(D) {  // NOLINT
@@ -81,19 +109,11 @@ class DDim {
 
   DDim operator*(const DDim& d) const;
 
-  // Make DDim act like std::vector<int64_t>
-  using iterator = int64_t*;
-  using const_iterator = const int64_t*;
-
-  int64_t* data() { return dim_.data(); }
-  const int64_t* data() const { return dim_.data(); }
+  inline const int64_t* Get() const { return dim_.Get(); }
 
-  iterator begin() { return data(); }
-  const_iterator begin() const { return data(); }
-  iterator end() { return data() + rank_; }
-  const_iterator end() const { return data() + rank_; }
+  inline int64_t* GetMutable() { return dim_.GetMutable(); }
 
-  int size() const { return rank_; }
+  inline int size() const { return rank_; }
 
  private:
   template <int M>
diff --git a/paddle/fluid/framework/dim.h b/paddle/fluid/framework/dim.h
index 3ae60a3119e1b55c9b60ddb607101ebd5222a5ac..21d91167a4475466ec77fce7f47edb5800e74dca 100644
--- a/paddle/fluid/framework/dim.h
+++ b/paddle/fluid/framework/dim.h
@@ -54,10 +54,6 @@ class Dim : public Array<int64_t, N> {
 
   HOSTDEVICE Dim() = default;
 
-  HOSTDEVICE int64_t* data() { return this->GetMutable(); }
-
-  HOSTDEVICE const int64_t* data() const { return this->Get(); }
-
   HOST std::string to_string() const;
 };
 
@@ -283,5 +279,10 @@ HOSTDEVICE Dim<N> linear_to_dimension(int linear_index, const Dim<N>& extents) {
   return result;
 }
 
+template <int D, typename T1, typename T2>
+inline void static_dim_assign(const T1* in, T2* out) {
+  UnrollAssign<D>::Run(in, out);
+}
+
 }  // namespace framework
 }  // namespace paddle