Remove V8_HOST_CAN_READ_UNALIGNED and its uses.

Remove V8_HOST_CAN_READ_UNALIGNED and its uses.

R=jkummerow@chromium.org
BUG=chromium:412967
LOG=Y

Committed: https://code.google.com/p/v8/source/detail?r=23915

[Jakob Kummerow, 2014-09-12 11:08:44]

LGTM with comments.

https://codereview.chromium.org/568753002/diff/1/src/deoptimizer.h
File src/deoptimizer.h (right):

https://codereview.chromium.org/568753002/diff/1/src/deoptimizer.h#newcode26
src/deoptimizer.h:26: c.u[0] = Memory::uint32_at(p);
Since Memory::uint32_at does a reinterpret_cast<uint32_t*>, this is only safe
when p is 4-byte aligned. I understand that this is guaranteed by current
callers, but please add a comment and/or DCHECK to make it explicit.

https://codereview.chromium.org/568753002/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/568753002/diff/1/src/objects.cc#newcode8510
src/objects.cc:8510: return CompareChars(a, b, length) == 0;
Nice!

https://codereview.chromium.org/568753002/diff/1/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/568753002/diff/1/src/runtime.cc#newcode6580
src/runtime.cc:6580: *reinterpret_cast<uintptr_t*>(dst) = w;
Who guarantees that dst is aligned here?

[Jakob Kummerow, 2014-09-12 11:45:47]

lgtm

[Yang, 2014-09-12 12:42:17]

Committed patchset #2 (id:20001) manually as 23915 (presubmit successful).

[Sven Panne, 2014-09-12 13:12:07]

svenpanne@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Sven Panne, 2014-09-12 13:12:08]

A bit late, but...

https://codereview.chromium.org/568753002/diff/1/src/deoptimizer.h
File src/deoptimizer.h (right):

https://codereview.chromium.org/568753002/diff/1/src/deoptimizer.h#newcode26
src/deoptimizer.h:26: c.u[0] = Memory::uint32_at(p);
On 2014/09/12 11:08:44, Jakob wrote:
> Since Memory::uint32_at does a reinterpret_cast<uint32_t*>, this is only safe
> when p is 4-byte aligned. I understand that this is guaranteed by current
> callers, but please add a comment and/or DCHECK to make it explicit.

Even simpler: Just use memcpy...