Implement WASM big-endian support

src/utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_UTILS_H_
 #define V8_UTILS_H_
 
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 1534 matching lines @@
 }
 
 static inline uint32_t ReadUnalignedUInt32(const void* p) {
   return ReadUnalignedValue<uint32_t>(p);
 }
 
 static inline void WriteUnalignedUInt32(void* p, uint32_t value) {
   WriteUnalignedValue(p, value);
 }
 
+template <typename V>
+static inline V ReadLittleEndianValue(const void* p) {
+#if defined(V8_TARGET_LITTLE_ENDIAN)
+  return ReadUnalignedValue<V>(p);
+#elif defined(V8_TARGET_BIG_ENDIAN)
+  V ret = 0;
+  const byte* src = reinterpret_cast<const byte*>(p);
+  byte* dst = reinterpret_cast<byte*>(&ret);
+  for (size_t i = 0; i < sizeof(V); i++) {
+    dst[i] = src[sizeof(V) - i - 1];
+  }
+  return ret;
+#endif  // V8_TARGET_LITTLE_ENDIAN
+}
+
+template <typename V>
+static inline void WriteLittleEndianValue(void* p, V value) {
+#if defined(V8_TARGET_LITTLE_ENDIAN)
+  WriteUnalignedValue<V>(p, value);
+#elif defined(V8_TARGET_BIG_ENDIAN)
+  byte* src = reinterpret_cast<byte*>(&value);
+  byte* dst = reinterpret_cast<byte*>(p);
+  for (size_t i = 0; i < sizeof(V); i++) {
+    dst[i] = src[sizeof(V) - i - 1];
+  }
+#endif  // V8_TARGET_LITTLE_ENDIAN
+}
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UTILS_H_