[WASM] Add const in C++ where applicable (tensorflow#2324)

DEV

tfjs-backend-wasm/src/cc/backend.cc

@@ -44,9 +44,8 @@ int xnn_operator_count = 0;
 // Registers a disposal callback for a tensor id with a given callback function.
 void register_disposal_callback(int tensor_id, DisposeFunction dispose_fn) {
   if (disposal_callbacks.count(tensor_id) == 0) {
-    auto callbacks = std::vector<DisposeFunction>{dispose_fn};
     // We move callbacks to avoid a copy.
-    disposal_callbacks.insert({tensor_id, std::move(callbacks)});
+    disposal_callbacks.insert({tensor_id, {dispose_fn}});
   } else {
     auto &callbacks = disposal_callbacks[tensor_id];
     callbacks.push_back(dispose_fn);
@@ -84,8 +83,8 @@ void dispose_data(int tensor_id) {
   // Call all disposal callbacks for this tensor id.
   auto disposal_callback_idx = disposal_callbacks.find(tensor_id);
   if (disposal_callback_idx != disposal_callbacks.end()) {
-    auto callbacks = disposal_callback_idx->second;
-    for (auto dispose_function : callbacks) {
+    auto &callbacks = disposal_callback_idx->second;
+    for (auto &dispose_function : callbacks) {
       dispose_function(tensor_id);
     }
 
@@ -100,10 +99,10 @@ void dispose() {
   // We have to create a separate vector of tensor ids because we erase from the
   // map while we're iterating it.
   std::vector<int> tensor_ids_to_dispose;
-  for (auto const &element : data) {
+  for (const auto &element : data) {
     tensor_ids_to_dispose.push_back(element.first);
   }
-  for (auto const tensor_id : tensor_ids_to_dispose) {
+  for (const auto tensor_id : tensor_ids_to_dispose) {
     dispose_data(tensor_id);
   }
 

tfjs-backend-wasm/src/cc/util.cc

@@ -19,7 +19,7 @@
 namespace tfjs {
 namespace util {
 
-std::vector<int> compute_strides(const std::vector<int> shape) {
+const std::vector<int> compute_strides(const std::vector<int> shape) {
   int rank = shape.size();
   std::vector<int> strides(rank - 1);
   // Last dimension has implicit stride of 1, thus having D-1 (instead of D)

tfjs-backend-wasm/src/cc/util.h

@@ -67,7 +67,7 @@ inline void warn(const char* format, ...) {
 template <class T>
 inline void log_vector(const std::vector<T>& v) {
   print_log("[", 0);
-  for (auto const& value : v) {
+  for (const auto& value : v) {
     print_log("%d,", value);
   }
   print_log("]\n", 0);
@@ -83,8 +83,8 @@ inline int size_from_shape(const std::vector<int>& shape) {
 }
 
 // Returns the indices of an n-dim tensor given the flat offset and its strides.
-inline std::vector<int> offset_to_loc(int index,
-                                      const std::vector<int>& strides) {
+inline const std::vector<int> offset_to_loc(int index,
+                                            const std::vector<int>& strides) {
   int rank = strides.size() + 1;
   std::vector<int> loc(rank);
   if (rank == 0) {
@@ -139,7 +139,7 @@ inline int offset(int i1, int i2, int i3, int i4, int i5, int s1, int s2,
 
 // Returns the strides of a tensor given its shape. Note that the strides
 // are of length R-1 where R is the rank of the tensor.
-std::vector<int> compute_strides(const std::vector<int> shape);
+const std::vector<int> compute_strides(const std::vector<int> shape);
 
 }  // namespace util
 }  // namespace tfjs