MIPS: Fix unaligned read of bytecodes in interpreter.

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index 0426ce51cb7dd1ea5e49663fb4c71dcc1a6a8b2f..1fe6a3213c776251dd96121f242ef363d49f0c60 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -1734,6 +1734,42 @@ static inline void WriteDoubleValue(void* p, double value) {
 #endif  // V8_TARGET_ARCH_MIPS
 }
 
+
+static inline uint16_t ReadUnalignedUInt16(const void* p) {
+#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64)
+  return *reinterpret_cast<const uint16_t*>(p);
+#else   // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+  // Prevent compiler from using load-half (mips lh) on (possibly)
+  // non-16-bit aligned address.
+  union conversion {
+    uint16_t h;
+    uint8_t b[2];
+  } c;
+  const uint8_t* ptr = reinterpret_cast<const uint8_t*>(p);
+  c.b[0] = *ptr;
+  c.b[1] = *(ptr + 1);
+  return c.h;
+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+}
+
+
+static inline void WriteUnalignedUInt16(void* p, uint16_t value) {
+#if !(V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64)
+  *(reinterpret_cast<uint16_t*>(p)) = value;
+#else   // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+  // Prevent compiler from using store-half (mips sh) on (possibly)
+  // non-16-bit aligned address.
+  union conversion {
+    uint16_t h;
+    uint8_t b[2];
+  } c;
+  c.h = value;
+  uint8_t* ptr = reinterpret_cast<uint8_t*>(p);
+  *ptr = c.b[0];
+  *(ptr + 1) = c.b[1];
+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+}
+
 }  // namespace internal
 }  // namespace v8