fix zerocopy size

paddle/fluid/inference/api/helper.h

@@ -204,11 +204,14 @@ static std::string DescribeTensor(const PaddleTensor &tensor) {
     os << to_string(l) << "; ";
   }
   os << "\n";
-  os << " - data: ";
+  os << " - memory length: " << tensor.data.length();
+  os << "\n";
 
+  os << " - data: ";
   int dim = VecReduceToInt(tensor.shape);
+  float *pdata = static_cast<float *>(tensor.data.data());
   for (int i = 0; i < dim; i++) {
-    os << static_cast<float *>(tensor.data.data())[i] << " ";
+    os << pdata[i] << " ";
   }
   os << '\n';
   return os.str();
@@ -224,10 +227,12 @@ static std::string DescribeZeroCopyTensor(const ZeroCopyTensor &tensor) {
     os << to_string(l) << "; ";
   }
   os << "\n";
-  os << " - data: ";
   PaddlePlace place;
   int size;
   const auto *data = tensor.data<float>(&place, &size);
+  os << " - numel: " << size;
+  os << "\n";
+  os << " - data: ";
   for (int i = 0; i < size; i++) {
     os << data[i] << " ";
   }

paddle/fluid/inference/api/paddle_api.h

@@ -123,7 +123,8 @@ class ZeroCopyTensor {
    */
   template <typename T>
   T* mutable_data(PaddlePlace place);
-  /** Get the memory directly, will return the place and memory size by pointer.
+  /** Get the memory directly, will return the place and element size by
+   * pointer.
    * This is for reading the output tensor.
    */
   template <typename T>

paddle/fluid/inference/tests/api/analyzer_rnn1_tester.cc

@@ -351,10 +351,10 @@ TEST(Analyzer_rnn1, ZeroCopy) {
   ASSERT_TRUE(native_predictor->Run(native_inputs.front(), &native_outputs));
   LOG(INFO) << "native output " << DescribeTensor(native_outputs.front());
 
-  int output_size{0};
+  int output_size{0};  // this is the number of elements not memory size
   auto *zero_copy_data = output_tensor->data<float>(&place, &output_size);
   auto *native_data = static_cast<float *>(native_outputs.front().data.data());
-  for (size_t i = 0; i < output_size / sizeof(float); i++) {
+  for (int i = 0; i < output_size; i++) {
     EXPECT_NEAR(zero_copy_data[i], native_data[i], 1e-3);
   }
 }