Reland of "Implement WASM big-endian support".

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index 9b94a2feb1de6a7e9fcc8910ec3008e93f4a3bca..8e5ddf8896c7956f0f53f3511297bf8e568f06e8 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -1506,22 +1506,22 @@ inline uintptr_t GetCurrentStackPosition() {
 
 template <typename V>
 static inline V ReadUnalignedValue(const void* p) {
-#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64)
+#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM)
   return *reinterpret_cast<const V*>(p);
-#else
+#else   // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM
   V r;
   memmove(&r, p, sizeof(V));
   return r;
-#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM
 }
 
 template <typename V>
 static inline void WriteUnalignedValue(void* p, V value) {
-#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64)
+#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM)
   *(reinterpret_cast<V*>(p)) = value;
-#else   // V8_TARGET_ARCH_MIPS
+#else   // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM
   memmove(p, &value, sizeof(V));
-#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM
 }
 
 static inline double ReadFloatValue(const void* p) {
@@ -1552,6 +1552,33 @@ 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