Fix ~63 ClangTidy - Performance findings in TensorFlow.

Change: 131891101

26 files changed, 53 insertions, 45 deletions

diff --git a/tensorflow/core/common_runtime/bfc_allocator.cc b/tensorflow/core/common_runtime/bfc_allocator.cc
index 70b01d6485..f525d1d981 100644
--- a/tensorflow/core/common_runtime/bfc_allocator.cc
+++ b/tensorflow/core/common_runtime/bfc_allocator.cc
@@ -157,7 +157,7 @@ bool BFCAllocator::Extend(size_t rounded_bytes) {
   InsertFreeChunkIntoBin(h);
 
   // Invoke visitors on newly allocated region.
-  for (auto visitor : region_visitors_) {
+  for (const auto& visitor : region_visitors_) {
     visitor(mem_addr, bytes);
   }
   return true;
diff --git a/tensorflow/core/common_runtime/constant_folding.cc b/tensorflow/core/common_runtime/constant_folding.cc
index 9bd162b72f..6a49c940b3 100644
--- a/tensorflow/core/common_runtime/constant_folding.cc
+++ b/tensorflow/core/common_runtime/constant_folding.cc
@@ -279,7 +279,7 @@ bool ReplaceTensorWithConstant(Graph* graph, Device* partition_device,
       edges_to_remove.push_back(out_edge);
     }
   }
-  string node_name = n->name();
+  const string& node_name = n->name();
   Node* constant_node;
   auto builder = NodeDefBuilder(strings::StrCat(graph->NewName(node_name),
                                                 "__cf__", UniqueConstantId()),
diff --git a/tensorflow/core/common_runtime/copy_tensor.cc b/tensorflow/core/common_runtime/copy_tensor.cc
index 5dc8c33b2a..e55ef7d5ba 100644
--- a/tensorflow/core/common_runtime/copy_tensor.cc
+++ b/tensorflow/core/common_runtime/copy_tensor.cc
@@ -16,6 +16,7 @@ limitations under the License.
 #include "tensorflow/core/common_runtime/copy_tensor.h"
 
 #include <atomic>
+#include <utility>
 #include <vector>
 #include "tensorflow/core/lib/core/errors.h"
 #include "tensorflow/core/platform/logging.h"
@@ -26,7 +27,9 @@ namespace {
 
 struct RegistrationInfo {
   RegistrationInfo(DeviceType s, DeviceType r, CopyTensor::CopyFunction cf)
-      : sender_device_type(s), receiver_device_type(r), copy_function(cf) {}
+      : sender_device_type(std::move(s)),
+        receiver_device_type(r),
+        copy_function(cf) {}
   DeviceType sender_device_type;
   DeviceType receiver_device_type;
   CopyTensor::CopyFunction copy_function;
diff --git a/tensorflow/core/common_runtime/device_set.cc b/tensorflow/core/common_runtime/device_set.cc
index 98c6c3843c..8ff93760d4 100644
--- a/tensorflow/core/common_runtime/device_set.cc
+++ b/tensorflow/core/common_runtime/device_set.cc
@@ -71,9 +71,9 @@ std::vector<DeviceType> DeviceSet::PrioritizedDeviceTypeList() const {
   std::vector<DeviceType> result;
   std::set<string> seen;
   for (Device* d : devices_) {
-    auto t = d->device_type();
+    const auto& t = d->device_type();
     if (seen.insert(t).second) {
-      result.emplace_back(DeviceType(t));
+      result.emplace_back(t);
     }
   }
   std::sort(result.begin(), result.end(), DeviceTypeComparator);
diff --git a/tensorflow/core/common_runtime/function_test.cc b/tensorflow/core/common_runtime/function_test.cc
index 2f5507a0c5..e263e62bd8 100644
--- a/tensorflow/core/common_runtime/function_test.cc
+++ b/tensorflow/core/common_runtime/function_test.cc
@@ -144,7 +144,7 @@ class FunctionLibraryRuntimeTest : public ::testing::Test {
 
   void Init(const std::vector<FunctionDef>& flib) {
     FunctionDefLibrary proto;
-    for (auto fdef : flib) *(proto.add_function()) = fdef;
+    for (const auto& fdef : flib) *(proto.add_function()) = fdef;
     delete lib_def_;
     lib_def_ = new FunctionLibraryDefinition(OpRegistry::Global(), proto);
     delete lib_;
diff --git a/tensorflow/core/common_runtime/gpu/gpu_event_mgr.cc b/tensorflow/core/common_runtime/gpu/gpu_event_mgr.cc
index 7506e35ff3..f18ee5efd8 100644
--- a/tensorflow/core/common_runtime/gpu/gpu_event_mgr.cc
+++ b/tensorflow/core/common_runtime/gpu/gpu_event_mgr.cc
@@ -95,7 +95,7 @@ void EventMgr::ThenDeleteTensors(perftools::gputools::Stream* stream,
     FlushAccumulatedTensors();
   }
   accumulated_stream_ = stream;
-  for (auto t : tensors) {
+  for (const auto& t : tensors) {
     // accumulated_tensors_ takes over ownership of the reference to "t"
     accumulated_tensors_->push_back(t);
     accumulated_tensor_bytes_ += t.TotalBytes();
diff --git a/tensorflow/core/common_runtime/gpu/gpu_stream_util_test.cc b/tensorflow/core/common_runtime/gpu/gpu_stream_util_test.cc
index 5b4812bb34..3aaaf87e79 100644
--- a/tensorflow/core/common_runtime/gpu/gpu_stream_util_test.cc
+++ b/tensorflow/core/common_runtime/gpu/gpu_stream_util_test.cc
@@ -129,7 +129,7 @@ TEST_F(GpuStreamUtilTest, StreamOverrides) {
   // Nodes should be assigned to streams by op type.
   for (const auto& it : node_to_stream_id) {
     Node* n = g.FindNodeId(it.first);
-    const string op = n->type_string();
+    const string& op = n->type_string();
     const int stream = it.second;
     if (op == "Const") {
       EXPECT_EQ(stream, 90);
diff --git a/tensorflow/core/common_runtime/gpu/pool_allocator.cc b/tensorflow/core/common_runtime/gpu/pool_allocator.cc
index b44108d1ac..e0362b38e6 100644
--- a/tensorflow/core/common_runtime/gpu/pool_allocator.cc
+++ b/tensorflow/core/common_runtime/gpu/pool_allocator.cc
@@ -20,6 +20,7 @@ limitations under the License.
 #include <sys/mman.h>  // for munmap
 
 #include <map>
+#include <utility>
 
 #include "tensorflow/core/lib/strings/numbers.h"
 #include "tensorflow/core/platform/logging.h"
@@ -31,7 +32,7 @@ namespace tensorflow {
 PoolAllocator::PoolAllocator(size_t pool_size_limit, bool auto_resize,
                              SubAllocator* allocator,
                              RoundUpInterface* size_rounder, string name)
-    : name_(name),
+    : name_(std::move(name)),
       has_size_limit_(pool_size_limit > 0),
       auto_resize_(auto_resize),
       pool_size_limit_(pool_size_limit),
@@ -125,7 +126,7 @@ void* PoolAllocator::AllocateRaw(size_t alignment, size_t num_bytes) {
     return PrepareChunk(r, alignment, num_bytes);
   } else {
     void* ptr = allocator_->Alloc(kPoolAlignment, num_bytes);
-    for (auto v : alloc_visitors_) {
+    for (const auto& v : alloc_visitors_) {
       v(ptr, num_bytes);
     }
     return PrepareChunk(ptr, alignment, num_bytes);
@@ -137,7 +138,7 @@ void PoolAllocator::DeallocateRaw(void* ptr) {
   ChunkPrefix* cp = FindPrefix(ptr);
   CHECK_LE((void*)cp, (void*)ptr);
   if (!has_size_limit_ && !auto_resize_) {
-    for (auto v : free_visitors_) {
+    for (const auto& v : free_visitors_) {
       v(cp, cp->num_bytes);
     }
     allocator_->Free(cp, cp->num_bytes);
@@ -160,7 +161,7 @@ void PoolAllocator::Clear() {
     mutex_lock lock(mutex_);
     for (auto iter : pool_) {
       PtrRecord* pr = iter.second;
-      for (auto v : free_visitors_) {
+      for (const auto& v : free_visitors_) {
         v(pr->ptr, pr->num_bytes);
       }
       allocator_->Free(pr->ptr, pr->num_bytes);
@@ -217,7 +218,7 @@ void PoolAllocator::EvictOne() {
     DCHECK(iter != pool_.end());
   }
   pool_.erase(iter);
-  for (auto v : free_visitors_) {
+  for (const auto& v : free_visitors_) {
     v(prec->ptr, prec->num_bytes);
   }
   allocator_->Free(prec->ptr, prec->num_bytes);
diff --git a/tensorflow/core/common_runtime/simple_placer.cc b/tensorflow/core/common_runtime/simple_placer.cc
index 6e177da57f..2a9e0fa196 100644
--- a/tensorflow/core/common_runtime/simple_placer.cc
+++ b/tensorflow/core/common_runtime/simple_placer.cc
@@ -42,7 +42,7 @@ std::vector<Device*> FilterSupportedDevices(
     const std::vector<Device*>& devices,
     const DeviceTypeVector& supported_device_types) {
   std::vector<Device*> filtered_devices;
-  for (DeviceType d : supported_device_types) {
+  for (const DeviceType& d : supported_device_types) {
     for (Device* device : devices) {
       if (DeviceType(device->attributes().device_type()) == d) {
         filtered_devices.emplace_back(device);
@@ -495,7 +495,7 @@ class ColocationGraph {
                                 "' does not match any device");
       }
 
-      for (DeviceType d : member->supported_device_types) {
+      for (const DeviceType& d : member->supported_device_types) {
         if (DeviceType(assigned_device->attributes().device_type()) == d) {
           return Status::OK();
         }
@@ -545,9 +545,9 @@ class ColocationGraph {
     target->clear();
 
     // Iterate in priority order.
-    for (DeviceType device_type : temp) {
+    for (const DeviceType& device_type : temp) {
       bool found = false;
-      for (DeviceType other_device_type : other) {
+      for (const DeviceType& other_device_type : other) {
         if (device_type == other_device_type) {
           found = true;
           break;
diff --git a/tensorflow/core/framework/function.cc b/tensorflow/core/framework/function.cc
index 83676a90c5..bedc85ab4e 100644
--- a/tensorflow/core/framework/function.cc
+++ b/tensorflow/core/framework/function.cc
@@ -861,11 +861,11 @@ string DebugString(const GraphDef& instantiated_func_def) {
 
 string DebugStringWhole(const GraphDef& gdef) {
   string ret;
-  for (auto fdef : gdef.library().function()) {
+  for (const auto& fdef : gdef.library().function()) {
     strings::StrAppend(&ret, Print(fdef));
   }
   strings::StrAppend(&ret, "\n");
-  for (auto ndef : gdef.node()) {
+  for (const auto& ndef : gdef.node()) {
     strings::StrAppend(&ret, Print(ndef), "\n");
   }
   return ret;
diff --git a/tensorflow/core/framework/function_testlib.cc b/tensorflow/core/framework/function_testlib.cc
index 900ceed1a5..47db0f0339 100644
--- a/tensorflow/core/framework/function_testlib.cc
+++ b/tensorflow/core/framework/function_testlib.cc
@@ -31,11 +31,11 @@ GraphDef GDef(gtl::ArraySlice<NodeDef> nodes,
   VersionDef* versions = g.mutable_versions();
   versions->set_producer(TF_GRAPH_DEF_VERSION);
   versions->set_min_consumer(TF_GRAPH_DEF_VERSION_MIN_CONSUMER);
-  for (auto n : nodes) {
+  for (const auto& n : nodes) {
     *(g.add_node()) = n;
   }
   auto lib = g.mutable_library();
-  for (auto f : funcs) {
+  for (const auto& f : funcs) {
     *(lib->add_function()) = f;
   }
   return g;
@@ -49,7 +49,7 @@ NodeDef NDef(const string& name, const string& op,
   NodeDef n;
   n.set_name(name);
   n.set_op(op);
-  for (auto in : inputs) n.add_input(in);
+  for (const auto& in : inputs) n.add_input(in);
   n.set_device(device);
   for (auto na : attrs) n.mutable_attr()->insert({na.first, na.second.proto});
   return n;
diff --git a/tensorflow/core/framework/op_def_util.cc b/tensorflow/core/framework/op_def_util.cc
index 5717488b1c..c36e6dd653 100644
--- a/tensorflow/core/framework/op_def_util.cc
+++ b/tensorflow/core/framework/op_def_util.cc
@@ -60,7 +60,7 @@ Status AllowedTypeValue(DataType dt, const OpDef::AttrDef& attr) {
 
 Status AllowedStringValue(const string& str, const OpDef::AttrDef& attr) {
   const AttrValue& allowed_values(attr.allowed_values());
-  for (auto allowed : allowed_values.list().s()) {
+  for (const auto& allowed : allowed_values.list().s()) {
     if (str == allowed) {
       return Status::OK();
     }
diff --git a/tensorflow/core/framework/op_kernel_test.cc b/tensorflow/core/framework/op_kernel_test.cc
index db4b6037ef..b4556c9272 100644
--- a/tensorflow/core/framework/op_kernel_test.cc
+++ b/tensorflow/core/framework/op_kernel_test.cc
@@ -381,7 +381,7 @@ class OpKernelBuilderTest : public ::testing::Test {
     DeviceTypeVector devices;
     TF_EXPECT_OK(SupportedDeviceTypesForNode(DeviceTypes(), def, &devices));
     bool found = false;
-    for (DeviceType dt : devices) {
+    for (const DeviceType& dt : devices) {
       if (dt == device_type) {
         found = true;
       }
@@ -414,7 +414,7 @@ class OpKernelBuilderTest : public ::testing::Test {
       DeviceTypeVector devices;
       if (errors::IsNotFound(status)) {
         TF_EXPECT_OK(SupportedDeviceTypesForNode(DeviceTypes(), def, &devices));
-        for (DeviceType dt : devices) {
+        for (const DeviceType& dt : devices) {
           EXPECT_NE(dt, device_type);
         }
       } else {
diff --git a/tensorflow/core/graph/optimizer_cse_test.cc b/tensorflow/core/graph/optimizer_cse_test.cc
index 0841bac93c..1091af4e45 100644
--- a/tensorflow/core/graph/optimizer_cse_test.cc
+++ b/tensorflow/core/graph/optimizer_cse_test.cc
@@ -326,7 +326,7 @@ TEST_F(OptimizerCSETest, Constant_Dedup) {
 
   // A graph contains a bunch of constants.
   Graph g(OpRegistry::Global());
-  for (auto val : {a, b, c, d, d, c, b, a}) {
+  for (const auto& val : {a, b, c, d, d, c, b, a}) {
     test::graph::Constant(&g, val);  // Node name is n/_0, n/_1, ...
   }
   GraphDef gdef;
diff --git a/tensorflow/core/graph/quantize_training.cc b/tensorflow/core/graph/quantize_training.cc
index 8521dff6fa..930d7bd15f 100644
--- a/tensorflow/core/graph/quantize_training.cc
+++ b/tensorflow/core/graph/quantize_training.cc
@@ -74,7 +74,7 @@ inline bool IsGradientNode(const Graph* graph, const Node* node) {
 // Returns true if the root tensor op type is known, false otherwise.
 bool FindType(const Graph* graph, const Node* node, bool* signed_input,
               bool* range_given, float* input_min, float* input_max) {
-  const string src_op = node->type_string();
+  const string& src_op = node->type_string();
   if (src_op == "Const" || src_op == "Variable") {
     *signed_input = true;
     *range_given = false;
diff --git a/tensorflow/core/kernels/argmax_op.cc b/tensorflow/core/kernels/argmax_op.cc
index 595bd7bd5e..2f92a2da9f 100644
--- a/tensorflow/core/kernels/argmax_op.cc
+++ b/tensorflow/core/kernels/argmax_op.cc
@@ -67,7 +67,7 @@ class ArgOp : public OpKernel {
                                 input.shape().DebugString()));
 
     TensorShape output_shape;
-    TensorShape input_shape = input.shape();
+    const TensorShape& input_shape = input.shape();
     for (int d = 0; d < input_dims - 1; ++d) {
       output_shape.AddDim(input_shape.dim_size((d < dim) ? d : d + 1));
     }
diff --git a/tensorflow/core/kernels/attention_ops.cc b/tensorflow/core/kernels/attention_ops.cc
index 695068d315..cc8f122cab 100644
--- a/tensorflow/core/kernels/attention_ops.cc
+++ b/tensorflow/core/kernels/attention_ops.cc
@@ -41,7 +41,7 @@ class ExtractGlimpseOp : public OpKernel {
   // depth).
   void Compute(OpKernelContext* context) override {
     const Tensor& input = context->input(0);
-    const TensorShape input_shape = input.shape();
+    const TensorShape& input_shape = input.shape();
     const int32 num_dims = input_shape.dims();
     OP_REQUIRES(
         context, num_dims == 4,
diff --git a/tensorflow/core/kernels/candidate_sampler_ops.cc b/tensorflow/core/kernels/candidate_sampler_ops.cc
index d64dca3d0b..6aa9059dc7 100644
--- a/tensorflow/core/kernels/candidate_sampler_ops.cc
+++ b/tensorflow/core/kernels/candidate_sampler_ops.cc
@@ -190,7 +190,7 @@ class ComputeAccidentalHitsOp : public OpKernel {
 
   void Compute(OpKernelContext* context) override {
     const Tensor& in_true_candidates = context->input(0);
-    TensorShape in_true_candidates_shape = in_true_candidates.shape();
+    const TensorShape& in_true_candidates_shape = in_true_candidates.shape();
     OP_REQUIRES(context, TensorShapeUtils::IsMatrix(in_true_candidates_shape) &&
                              in_true_candidates_shape.dim_size(1) == num_true_,
                 errors::InvalidArgument(
diff --git a/tensorflow/core/kernels/gather_nd_op.cc b/tensorflow/core/kernels/gather_nd_op.cc
index c2a5192efb..73f30cdae3 100644
--- a/tensorflow/core/kernels/gather_nd_op.cc
+++ b/tensorflow/core/kernels/gather_nd_op.cc
@@ -53,7 +53,7 @@ class GatherNdOp : public OpKernel {
             "index innermost dimension length must be <= params rank; saw: ",
             indices.dim_size(indices.dims() - 1), " vs. ", params.dims()));
 
-    TensorShape indices_shape(indices.shape());
+    const TensorShape& indices_shape(indices.shape());
     const int64 indices_nd = indices_shape.dim_size(indices_shape.dims() - 1);
 
     // Check that we have enough index space
@@ -79,7 +79,7 @@ class GatherNdOp : public OpKernel {
       N_result *= indices_shape.dim_size(i);
     }
 
-    TensorShape params_shape(params.shape());
+    const TensorShape& params_shape(params.shape());
     Index total_nd = params_shape.dims();
 
     TensorShape result_shape(indices_shape);
diff --git a/tensorflow/core/kernels/maxpooling_op.cc b/tensorflow/core/kernels/maxpooling_op.cc
index 97e2bfcad5..27888d3a31 100644
--- a/tensorflow/core/kernels/maxpooling_op.cc
+++ b/tensorflow/core/kernels/maxpooling_op.cc
@@ -272,7 +272,7 @@ class MaxPoolingGradOp : public OpKernel {
     OP_REQUIRES(context, out_backprop.dims() == 4,
                 errors::InvalidArgument("out_backprop must be 4-dimensional"));
 
-    TensorShape output_shape = tensor_in.shape();
+    const TensorShape& output_shape = tensor_in.shape();
 
     Tensor tensor_out_dup;
     OP_REQUIRES_OK(context,
diff --git a/tensorflow/core/kernels/scan_ops.cc b/tensorflow/core/kernels/scan_ops.cc
index 604e712b0f..2604b73844 100644
--- a/tensorflow/core/kernels/scan_ops.cc
+++ b/tensorflow/core/kernels/scan_ops.cc
@@ -58,7 +58,7 @@ public:
         errors::InvalidArgument("ScanOp: Expected scan axis in the range [", 0,
                                 ", ", input.dims(), "), but got ", axis));
 
-    TensorShape output_shape = input.shape();
+    const TensorShape& output_shape = input.shape();
     Tensor* output = nullptr;
     OP_REQUIRES_OK(ctx, ctx->allocate_output(0, output_shape, &output));
 
diff --git a/tensorflow/core/lib/jpeg/jpeg_mem.cc b/tensorflow/core/lib/jpeg/jpeg_mem.cc
index 9a317f1fd2..ac12798322 100644
--- a/tensorflow/core/lib/jpeg/jpeg_mem.cc
+++ b/tensorflow/core/lib/jpeg/jpeg_mem.cc
@@ -23,6 +23,7 @@ limitations under the License.
 #include <algorithm>
 #include <memory>
 #include <string>
+#include <utility>
 
 #include "tensorflow/core/lib/jpeg/jpeg_handle.h"
 #include "tensorflow/core/platform/logging.h"
@@ -52,7 +53,7 @@ class FewerArgsForCompiler {
       : datasize_(datasize),
         flags_(flags),
         pnwarn_(nwarn),
-        allocate_output_(allocate_output),
+        allocate_output_(std::move(allocate_output)),
         height_read_(0),
         height_(0),
         stride_(0) {
diff --git a/tensorflow/core/platform/cloud/gcs_file_system.cc b/tensorflow/core/platform/cloud/gcs_file_system.cc
index 7426006cec..fc35c293d2 100644
--- a/tensorflow/core/platform/cloud/gcs_file_system.cc
+++ b/tensorflow/core/platform/cloud/gcs_file_system.cc
@@ -92,7 +92,7 @@ class GcsRandomAccessFile : public RandomAccessFile {
       : bucket_(bucket),
         object_(object),
         auth_provider_(auth_provider),
-        http_request_factory_(std::move(http_request_factory)),
+        http_request_factory_(http_request_factory),
         read_ahead_bytes_(read_ahead_bytes) {}
 
   /// The implementation of reads with a read-ahead buffer.
@@ -189,7 +189,7 @@ class GcsWritableFile : public WritableFile {
       : bucket_(bucket),
         object_(object),
         auth_provider_(auth_provider),
-        http_request_factory_(std::move(http_request_factory)) {
+        http_request_factory_(http_request_factory) {
     if (GetTmpFilename(&tmp_content_filename_).ok()) {
       outfile_.open(tmp_content_filename_,
                     std::ofstream::binary | std::ofstream::app);
@@ -208,7 +208,7 @@ class GcsWritableFile : public WritableFile {
       : bucket_(bucket),
         object_(object),
         auth_provider_(auth_provider),
-        http_request_factory_(std::move(http_request_factory)) {
+        http_request_factory_(http_request_factory) {
     tmp_content_filename_ = tmp_content_filename;
     outfile_.open(tmp_content_filename_,
                   std::ofstream::binary | std::ofstream::app);
diff --git a/tensorflow/core/util/tensor_slice_reader.cc b/tensorflow/core/util/tensor_slice_reader.cc
index 9ab81af43b..b40f5e7736 100644
--- a/tensorflow/core/util/tensor_slice_reader.cc
+++ b/tensorflow/core/util/tensor_slice_reader.cc
@@ -15,6 +15,7 @@ limitations under the License.
 
 #include "tensorflow/core/util/tensor_slice_reader.h"
 
+#include <utility>
 #include <vector>
 #include "tensorflow/core/framework/types.pb_text.h"
 #include "tensorflow/core/framework/versions.h"
@@ -107,7 +108,7 @@ TensorSliceReader::TensorSliceReader(const string& filepattern,
 TensorSliceReader::TensorSliceReader(const string& filepattern,
                                      OpenTableFunction open_function,
                                      int preferred_shard)
-    : filepattern_(filepattern), open_function_(open_function) {
+    : filepattern_(filepattern), open_function_(std::move(open_function)) {
   VLOG(1) << "TensorSliceReader for " << filepattern;
   Status s = io::GetMatchingFiles(Env::Default(), filepattern, &fnames_);
   if (!s.ok()) {
diff --git a/tensorflow/core/util/tensor_slice_set.cc b/tensorflow/core/util/tensor_slice_set.cc
index d4b9a4087c..4217df90ca 100644
--- a/tensorflow/core/util/tensor_slice_set.cc
+++ b/tensorflow/core/util/tensor_slice_set.cc
@@ -42,7 +42,7 @@ Status TensorSliceSet::Register(const TensorSlice& slice, const string& tag,
     // We check if there is any intersection between this slice and any of the
     // registered slices.
     if (slices_hull_.Overlaps(slice)) {
-      for (const auto x : slices_) {
+      for (const auto& x : slices_) {
         if (slice.Overlaps(x.second.slice)) {
           return errors::Internal("Overlapping slices: existing slice = ",
                                   x.first, ", new slice = ", str);
@@ -89,7 +89,7 @@ bool TensorSliceSet::Query(const TensorSlice& slice, float* data) const {
     int64 overlap_size = 0;
     TensorSlice intersection;
     TensorShape inter_shape;
-    for (const auto x : slices_) {
+    for (const auto& x : slices_) {
       if (slice.Intersect(x.second.slice, &intersection)) {
         s = intersection.SliceTensorShape(shape_, &inter_shape);
         if (!s.ok()) {
@@ -103,7 +103,7 @@ bool TensorSliceSet::Query(const TensorSlice& slice, float* data) const {
       // We have it!
       // Now we need to copy the data to "data"
       if (data) {
-        for (const auto x : slices_) {
+        for (const auto& x : slices_) {
           CopyDataFromTensorSliceToTensorSlice(shape_, x.second.slice, slice,
                                                x.second.data, data);
         }
@@ -146,7 +146,7 @@ bool TensorSliceSet::QueryMeta(
     int64 overlap_size = 0;
     TensorSlice intersection;
     TensorShape inter_shape;
-    for (const auto x : slices_) {
+    for (const auto& x : slices_) {
       if (slice.Intersect(x.second.slice, &intersection)) {
         s = intersection.SliceTensorShape(shape_, &inter_shape);
         if (!s.ok()) {
@@ -180,7 +180,7 @@ Status RegisterTensorSlice(
     tensor_slices->insert(std::make_pair(name, tss));
   } else {
     // Check if the shapes match
-    TensorShape tss_shape(tss->shape());
+    const TensorShape& tss_shape(tss->shape());
     if (!shape.IsSameSize(tss_shape)) {
       return errors::Internal("Incompatible tensor shapes detected for tensor ",
                               name, ": existing = ", tss_shape.DebugString(),
diff --git a/tensorflow/core/util/tensor_slice_writer.cc b/tensorflow/core/util/tensor_slice_writer.cc
index 8907aa6522..928d6fe72c 100644
--- a/tensorflow/core/util/tensor_slice_writer.cc
+++ b/tensorflow/core/util/tensor_slice_writer.cc
@@ -15,6 +15,8 @@ limitations under the License.
 
 #include "tensorflow/core/util/tensor_slice_writer.h"
 
+#include <utility>
+
 #include "tensorflow/core/lib/core/errors.h"
 #include "tensorflow/core/lib/io/table_builder.h"
 #include "tensorflow/core/lib/random/random.h"
@@ -81,7 +83,7 @@ Status CreateTableTensorSliceBuilder(const string& name,
 TensorSliceWriter::TensorSliceWriter(const string& filename,
                                      CreateBuilderFunction create_builder)
     : filename_(filename),
-      create_builder_(create_builder),
+      create_builder_(std::move(create_builder)),
       tmpname_(strings::StrCat(filename, ".tempstate", random::New64())),
       slices_(0) {
   VersionDef* versions = sts_.mutable_meta()->mutable_versions();