turn template specializations into instantiations, test=develop (#4015)

lite/api/paddle_api.cc

@@ -78,50 +78,28 @@ void Tensor::Resize(const shape_t &shape) {
   tensor(raw_tensor_)->Resize(shape);
 }
 
-// Tensor::data
-template <>
-const float *Tensor::data() const {
-  return ctensor(raw_tensor_)->data<float>();
-}
-template <>
-const int8_t *Tensor::data() const {
-  return ctensor(raw_tensor_)->data<int8_t>();
-}
-template <>
-const uint8_t *Tensor::data() const {
-  return ctensor(raw_tensor_)->data<uint8_t>();
-}
-template <>
-const int64_t *Tensor::data() const {
-  return ctensor(raw_tensor_)->data<int64_t>();
-}
-template <>
-const int32_t *Tensor::data() const {
-  return ctensor(raw_tensor_)->data<int32_t>();
+template <typename T>
+const T *Tensor::data() const {
+  return ctensor(raw_tensor_)->data<T>();
 }
 
-// Tensor::mutable_data
-template <>
-int *Tensor::mutable_data(TargetType type) const {
-  return tensor(raw_tensor_)->mutable_data<int>(type);
-}
-template <>
-float *Tensor::mutable_data(TargetType type) const {
-  return tensor(raw_tensor_)->mutable_data<float>(type);
-}
-template <>
-int8_t *Tensor::mutable_data(TargetType type) const {
-  return tensor(raw_tensor_)->mutable_data<int8_t>(type);
-}
-template <>
-uint8_t *Tensor::mutable_data(TargetType type) const {
-  return tensor(raw_tensor_)->mutable_data<uint8_t>(type);
-}
-template <>
-int64_t *Tensor::mutable_data(TargetType type) const {
-  return tensor(raw_tensor_)->mutable_data<int64_t>(type);
+template <typename T>
+T *Tensor::mutable_data(TargetType type) const {
+  return tensor(raw_tensor_)->mutable_data<T>(type);
 }
 
+template const float *Tensor::data<float>() const;
+template const int8_t *Tensor::data<int8_t>() const;
+template const uint8_t *Tensor::data<uint8_t>() const;
+template const int64_t *Tensor::data<int64_t>() const;
+template const int32_t *Tensor::data<int32_t>() const;
+
+template int *Tensor::mutable_data(TargetType type) const;
+template float *Tensor::mutable_data(TargetType type) const;
+template int8_t *Tensor::mutable_data(TargetType type) const;
+template uint8_t *Tensor::mutable_data(TargetType type) const;
+template int64_t *Tensor::mutable_data(TargetType type) const;
+
 template <typename T, TargetType type>
 void Tensor::CopyFromCpu(const T *src_data) {
   T *data = tensor(raw_tensor_)->mutable_data<T>(type);