[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n

Committed: https://crrev.com/af677d7b34df41c6e65558a925b2b33398b38c30
Cr-Commit-Position: refs/heads/master@{#35998}

[binji, 2016-05-03 19:04:55]

Description was changed from

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

BUG=v8:4614
LOG=n
==========

to

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

[binji, 2016-05-03 19:04:55]

binji@chromium.org changed reviewers:
+ bmeurer@chromium.org

[Dan Ehrenberg, 2016-05-03 19:05:49]

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

[Dan Ehrenberg, 2016-05-03 19:05:50]

lgtm

This code looks reasonable to me, but it's not my main area. It is needed to fix
a build which is broken due to https://codereview.chromium.org/1938213002 --
that patch emits new instructions, but then they cannot be disassembled, and
this patch addresses that.

[binji, 2016-05-03 19:09:31]

Description was changed from

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

to

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

[binji, 2016-05-03 19:09:50]

Description was changed from

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

to

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

[binji, 2016-05-03 19:09:54]

The CQ bit was checked by binji@chromium.org

[commit-bot: I haz the power, 2016-05-03 19:10:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1947673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1947673002/1

[commit-bot: I haz the power, 2016-05-03 19:58:26]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-03 20:00:43]

Description was changed from

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n
==========

to

==========
[Atomics] Fix disassembly for ia32 xchg_b and xchg_w

https://codereview.chromium.org/1938213002 added xchg_b and xchg_w, but didn't
add it to the disassembler, and there were no tests that caught it.

BUG=v8:4614
TBR=bmeurer@chromium.org
LOG=n

Committed: https://crrev.com/af677d7b34df41c6e65558a925b2b33398b38c30
Cr-Commit-Position: refs/heads/master@{#35998}
==========

[commit-bot: I haz the power, 2016-05-03 20:00:44]

Patchset 1 (id:??) landed as
https://crrev.com/af677d7b34df41c6e65558a925b2b33398b38c30
Cr-Commit-Position: refs/heads/master@{#35998}

[Benedikt Meurer, 2016-05-04 05:42:00]

LGTM.