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

[arm] Avoid unaligned access fault in Int32x4/Float32x4::value().

R=zra@google.com

Committed: https://github.com/dart-lang/sdk/commit/dddd96cfd2984f4c157b8c3632ad2b5dcb25b9fc

[rmacnak, 2017-06-20 00:50:10]

rmacnak@google.com changed reviewers:
+ zra@google.com

[rmacnak, 2017-06-20 00:50:11]

Tried using a temp marked with 4 byte alignment, but gcc generated the same
code.

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

https://codereview.chromium.org/2947783002/diff/1/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://codereview.chromium.org/2947783002/diff/1/runtime/vm/object.cc#newcod...
runtime/vm/object.cc:22355: #if defined(HOST_ARCH_ARM)
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.

[rmacnak, 2017-06-21 01:07:00]

Expanded on ReadUnaligned from globals.h.

[zra, 2017-06-21 06:40:29]

lgtm

[rmacnak, 2017-06-21 16:09:23]

Description was changed from

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

to

==========
[arm] Avoid unaligned access fault in Int32x4/Float32x4::value().
==========

[rmacnak, 2017-06-21 16:11:09]

Description was changed from

==========
[arm] Avoid unaligned access fault in Int32x4/Float32x4::value().
==========

to

==========
[arm] Avoid unaligned access fault in Int32x4/Float32x4::value().

R=zra@google.com

Committed:
https://github.com/dart-lang/sdk/commit/dddd96cfd2984f4c157b8c3632ad2b5dcb25b9fc
==========

[rmacnak, 2017-06-21 16:11:10]

Committed patchset #3 (id:40001) manually as
dddd96cfd2984f4c157b8c3632ad2b5dcb25b9fc (presubmit successful).