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

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 728e2ffe6446a8833d056194b9aef8d727408440..8ae4f6575bc2f4f2f7c5a2fd1cf26e7946c8674d 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -22352,12 +22352,22 @@ RawFloat32x4* Float32x4::New(simd128_value_t value, Heap::Space space) {
 
 
 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
 }
 
 
@@ -22487,12 +22497,22 @@ int32_t Int32x4::w() const {
 
 
 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
 }