[typedarrays] Implement %TypedArray%.prototype.reverse in C++

src/elements.cc

Index: src/elements.cc
diff --git a/src/elements.cc b/src/elements.cc
index 6258da399c6c7d1983e71a4e4cee87745b055353..fd440a54be129a7a1c02ed75312c97d88827f9e2 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -1261,6 +1261,10 @@ class ElementsAccessorBase : public ElementsAccessor {
     return Subclass::LastIndexOfValueImpl(isolate, receiver, value, start_from);
   }
 
+  static void ReverseImpl(JSObject* receiver) { UNREACHABLE(); }
+
+  void Reverse(JSObject* receiver) final { Subclass::ReverseImpl(receiver); }
+
   static uint32_t GetIndexForEntryImpl(FixedArrayBase* backing_store,
                                        uint32_t entry) {
     return entry;
@@ -3035,6 +3039,19 @@ class TypedElementsAccessor
     } while (k-- != 0);
     return Just<int64_t>(-1);
   }
+
+  static void ReverseImpl(JSObject* receiver) {
+    DisallowHeapAllocation no_gc;
+    DCHECK(!WasNeutered(receiver));
+
+    BackingStore* elements = BackingStore::cast(receiver->elements());
+
+    uint32_t len = elements->length();
+    if (len == 0) return;
+
+    ctype* data = static_cast<ctype*>(elements->DataPtr());
+    std::reverse(data, data + len);
+  }
 };
 
 #define FIXED_ELEMENTS_ACCESSOR(Type, type, TYPE, ctype, size) \