Avoid unaligned access fault in Int32x4/Float32x4::value() on ARM.

runtime/platform/globals.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_PLATFORM_GLOBALS_H_
 #define RUNTIME_PLATFORM_GLOBALS_H_
 
 // __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
 // enable platform independent printf format specifiers.
 #ifndef __STDC_FORMAT_MACROS
@@ skipping 645 matching lines @@
 template <class D, class S>
 inline D bit_copy(const S& source) {
   D destination;
   // This use of memcpy is safe: source and destination cannot overlap.
   memcpy(&destination, reinterpret_cast<const void*>(&source),
          sizeof(destination));
   return destination;
 }
 
 
+#if defined(HOST_ARCH_ARM) || defined(HOST_ARCH_MIPS) ||                       \
+    defined(HOST_ARCH_ARM64)
 // Similar to bit_copy and bit_cast, but does take the type from the argument.
 template <typename T>
 static inline T ReadUnaligned(const T* ptr) {
   T value;
   memcpy(&value, ptr, sizeof(value));
   return value;
 }
 
 
+// Similar to bit_copy and bit_cast, but does take the type from the argument.
+template <typename T>
+static inline void StoreUnaligned(T* ptr, T value) {
+  memcpy(ptr, &value, sizeof(value));
+}
+#else   // !(HOST_ARCH_ARM || HOST_ARCH_MIPS || HOST_ARCH_ARM64)
+// Similar to bit_copy and bit_cast, but does take the type from the argument.
+template <typename T>
+static inline T ReadUnaligned(const T* ptr) {
+  return *ptr;
+}
+
+
+// Similar to bit_copy and bit_cast, but does take the type from the argument.
+template <typename T>
+static inline void StoreUnaligned(T* ptr, T value) {
+  *ptr = value;
+}
+#endif  // !(HOST_ARCH_ARM || HOST_ARCH_MIPS || HOST_ARCH_ARM64)
+
+
 // On Windows the reentrent version of strtok is called
 // strtok_s. Unify on the posix name strtok_r.
 #if defined(HOST_OS_WINDOWS)
 #define snprintf _snprintf
 #define strtok_r strtok_s
 #endif
 
 #if !defined(HOST_OS_WINDOWS)
 #if defined(TEMP_FAILURE_RETRY)
 // TEMP_FAILURE_RETRY is defined in unistd.h on some platforms. We should
@@ skipping 27 matching lines @@
 // tag in the ICData and check it when recreating the flow graph in
 // optimizing compiler. Enable it for other modes (product, release) if needed
 // for debugging.
 #if defined(DEBUG)
 #define TAG_IC_DATA
 #endif
 
 }  // namespace dart
 
 #endif  // RUNTIME_PLATFORM_GLOBALS_H_