add save op float16 support

Author: kexinzhao

paddle/fluid/operators/save_load_op_test.cc

@@ -61,3 +61,35 @@ TEST(SaveLoadOp, CPU) {
     }
   }
 }
+
+TEST(SaveLoadFP16Op, CPU) {
+  paddle::framework::Scope scope;
+  paddle::platform::CPUPlace place;
+
+  auto var = scope.Var("test_var");
+  auto tensor = var->GetMutable<paddle::framework::LoDTensor>();
+  tensor->Resize({3, 10});
+
+  float* expect = tensor->mutable_data<float>(place);
+  for (int64_t i = 0; i < tensor->numel(); ++i) {
+    expect[i] = static_cast<float>(i);
+  }
+
+  paddle::framework::AttributeMap attrs;
+  attrs.insert({"file_path", std::string("tensor.save")});
+  attrs.insert({"save_as_fp16", true});
+
+  auto save_op = paddle::framework::OpRegistry::CreateOp(
+      "save", {{"X", {"test_var"}}}, {}, attrs);
+  save_op->Run(scope, place);
+
+  auto load_var = scope.Var("out_var");
+  auto target = load_var->GetMutable<paddle::framework::LoDTensor>();
+  auto load_op = paddle::framework::OpRegistry::CreateOp(
+      "load", {}, {{"Out", {"out_var"}}}, attrs);
+  load_op->Run(scope, place);
+  paddle::platform::float16* actual = target->data<paddle::platform::float16>();
+  for (int64_t i = 0; i < tensor->numel(); ++i) {
+    EXPECT_EQ(expect[i], static_cast<float>(actual[i]));
+  }
+}

paddle/fluid/operators/save_op.cc

@@ -18,6 +18,7 @@ limitations under the License. */
 #include <numeric>
 
 #include "paddle/fluid/framework/data_type.h"
+#include "paddle/fluid/framework/data_type_transform.h"
 #include "paddle/fluid/framework/framework.pb.h"
 #include "paddle/fluid/framework/lod_tensor.h"
 #include "paddle/fluid/framework/op_registry.h"
@@ -68,6 +69,7 @@ class SaveOp : public framework::OperatorBase {
                const platform::Place &place) const override {
     auto filename = Attr<std::string>("file_path");
     auto overwrite = Attr<bool>("overwrite");
+    auto save_as_fp16 = Attr<bool>("save_as_fp16");
 
     if (FileExists(filename) && !overwrite) {
       PADDLE_THROW("%s is existed, cannot save to it when overwrite=false",
@@ -96,7 +98,18 @@ class SaveOp : public framework::OperatorBase {
     platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
     auto &dev_ctx = *pool.Get(place);
 
-    framework::SerializeToStream(fout, tensor, dev_ctx);
+    auto in_dtype = framework::ToDataType(tensor.type());
+    auto out_dtype = save_as_fp16 ? framework::proto::VarType::FP16 : in_dtype;
+
+    if (in_dtype != out_dtype) {
+      auto in_kernel_type = framework::OpKernelType(in_dtype, place);
+      auto out_kernel_type = framework::OpKernelType(out_dtype, place);
+      framework::LoDTensor out;
+      framework::TransDataType(in_kernel_type, out_kernel_type, tensor, &out);
+      framework::SerializeToStream(fout, out, dev_ctx);
+    } else {
+      framework::SerializeToStream(fout, tensor, dev_ctx);
+    }
   }
 };
 
@@ -114,6 +127,12 @@ This operator will serialize and write a tensor variable to file on disk.
                   "(boolean, default true)"
                   "Overwrite the output file if exist")
         .SetDefault(true);
+    AddAttr<bool>("save_as_fp16",
+                  "(boolean, default false)"
+                  "If true, the tensor will be converted to float16 data "
+                  "type and then saved. Otherwise, the tensor will be "
+                  "directly saved without data type conversion.")
+        .SetDefault(false);
     AddAttr<std::string>("file_path",
                          "(string)"
                          "The \"file_path\" where the variable will be saved.")