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

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 22334 matching lines @@
         Object::Allocate(Float32x4::kClassId, Float32x4::InstanceSize(), space);
     NoSafepointScope no_safepoint;
     result ^= raw;
   }
   result.set_value(value);
   return result.raw();
 }
 
 
 simd128_value_t Float32x4::value() const {
+#if defined(HOST_ARCH_ARM)

[zra, 2017/06/20 17:44:34]

I think you should be able to use bit_cast here. Also, It would be nice to avoid
introducing arch specific code in this file. This would be the only instance.
Maybe the code in platform/globals.h can be shuffled around. There's already
arch specific code in there.

+  simd128_value_t temp;
+  memmove(&temp, &raw_ptr()->value_[0], sizeof(temp));
+  return temp;
+#else
   return simd128_value_t().readFrom(&raw_ptr()->value_[0]);
+#endif
 }
 
 
 void Float32x4::set_value(simd128_value_t value) const {
+#if defined(HOST_ARCH_ARM)
+  memmove(const_cast<float*>(&raw_ptr()->value_[0]), &value, sizeof(value));
+#else
   StoreSimd128(&raw_ptr()->value_[0], value);
+#endif
 }
 
 
 void Float32x4::set_x(float value) const {
   StoreNonPointer(&raw_ptr()->value_[0], value);
 }
 
 
 void Float32x4::set_y(float value) const {
   StoreNonPointer(&raw_ptr()->value_[1], value);
@@ skipping 109 matching lines @@
   return raw_ptr()->value_[2];
 }
 
 
 int32_t Int32x4::w() const {
   return raw_ptr()->value_[3];
 }
 
 
 simd128_value_t Int32x4::value() const {
+#if defined(HOST_ARCH_ARM)
+  simd128_value_t temp;
+  memmove(&temp, &raw_ptr()->value_[0], sizeof(temp));
+  return temp;
+#else
   return simd128_value_t().readFrom(&raw_ptr()->value_[0]);
+#endif
 }
 
 
 void Int32x4::set_value(simd128_value_t value) const {
+#if defined(HOST_ARCH_ARM)
+  memmove(const_cast<int32_t*>(&raw_ptr()->value_[0]), &value, sizeof(value));
+#else
   StoreSimd128(&raw_ptr()->value_[0], value);
+#endif
 }
 
 
 const char* Int32x4::ToCString() const {
   int32_t _x = x();
   int32_t _y = y();
   int32_t _z = z();
   int32_t _w = w();
   return OS::SCreate(Thread::Current()->zone(), "[%08x, %08x, %08x, %08x]", _x,
                      _y, _z, _w);
@@ skipping 913 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart