[arm][arm64] Improve CountTrailingZero implementation.

Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach

Committed: https://crrev.com/0dfd7bcdaf38b974bdbb3f035059e5611ffc746b
Cr-Commit-Position: refs/heads/master@{#34028}

[Rodolph Perfetta (ARM), 2016-02-12 16:39:52]

Description was changed from

==========
[arm][arm64] Improve CountTrailingZero implementation.

Added a ReverseBits operator and used it to implement Ctz.

BUG=
==========

to

==========
Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach
==========

[Rodolph Perfetta (ARM), 2016-02-12 16:39:52]

rodolph.perfetta@arm.com changed reviewers:
+ ahaas@chromium.org, titzer@chromium.org

[titzer, 2016-02-14 11:18:35]

Looks mostly good. Can you also add some tests to
test/cctest/compiler/test-run-machops for the two new optional operators?

https://codereview.chromium.org/1698483002/diff/1/src/arm/simulator-arm.cc
File src/arm/simulator-arm.cc (right):

https://codereview.chromium.org/1698483002/diff/1/src/arm/simulator-arm.cc#ne...
src/arm/simulator-arm.cc:2650: static uint32_t ReverseBits(uint32_t value) {
Good candidate for src/base/bits.cc?

[Rodolph Perfetta, 2016-02-15 17:56:00]

rodolph.perfetta@gmail.com changed reviewers:
+ rodolph.perfetta@gmail.com

[Rodolph Perfetta, 2016-02-15 17:56:01]

New tests added.

https://codereview.chromium.org/1698483002/diff/1/src/arm/simulator-arm.cc
File src/arm/simulator-arm.cc (right):

https://codereview.chromium.org/1698483002/diff/1/src/arm/simulator-arm.cc#ne...
src/arm/simulator-arm.cc:2650: static uint32_t ReverseBits(uint32_t value) {
On 2016/02/14 11:18:34, titzer wrote:
> Good candidate for src/base/bits.cc?

Done.

[titzer, 2016-02-16 07:55:01]

lgtm

[Rodolph Perfetta (ARM), 2016-02-16 10:46:00]

The CQ bit was checked by rodolph.perfetta@arm.com

[commit-bot: I haz the power, 2016-02-16 10:46:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1698483002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1698483002/20001

[commit-bot: I haz the power, 2016-02-16 11:14:05]

Description was changed from

==========
Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach
==========

to

==========
Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach
==========

[commit-bot: I haz the power, 2016-02-16 11:14:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-02-16 11:14:35]

Description was changed from

==========
Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach
==========

to

==========
Added a ReverseBits operator and used it to implement Ctz.

Let me know if this is not the right approach

Committed: https://crrev.com/0dfd7bcdaf38b974bdbb3f035059e5611ffc746b
Cr-Commit-Position: refs/heads/master@{#34028}
==========

[commit-bot: I haz the power, 2016-02-16 11:14:36]

Patchset 2 (id:??) landed as
https://crrev.com/0dfd7bcdaf38b974bdbb3f035059e5611ffc746b
Cr-Commit-Position: refs/heads/master@{#34028}