[turbofan] Use sbfx in ARM64 instruction selector

[turbofan] Use sbfx in ARM64 instruction selector

Select sbfx for ((x << k) >> k) in ARM64 instruction selector, and similarly
for ubfx. This is a more generic version of the previous sxtb/h selector.

BUG=

Committed: https://crrev.com/6e6d956e1199d80e3e53739958d061b6a1c36fad
Cr-Commit-Position: refs/heads/master@{#28318}

[martyn.capewell, 2015-05-07 17:45:06]

martyn.capewell@arm.com changed reviewers:
+ bmeurer@chromium.org, ulan@chromium.org

[Benedikt Meurer, 2015-05-08 04:05:00]

LGTM with nit.

https://codereview.chromium.org/1135543002/diff/1/src/compiler/arm64/instruct...
File src/compiler/arm64/instruction-selector-arm64.cc (right):

https://codereview.chromium.org/1135543002/diff/1/src/compiler/arm64/instruct...
src/compiler/arm64/instruction-selector-arm64.cc:663: bool
TryEmitBitfieldExtract32(InstructionSelector* selector, Node* node) {
Nit: put this function into an anonymous namespace.

[martyn.capewell, 2015-05-08 12:27:10]

The CQ bit was checked by martyn.capewell@arm.com

[martyn.capewell, 2015-05-08 12:27:11]

The patchset sent to the CQ was uploaded after l-g-t-m from bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/1135543002/#ps20001
(title: "Add anonymous namespace")

[commit-bot: I haz the power, 2015-05-08 12:27:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1135543002/20001

[commit-bot: I haz the power, 2015-05-08 12:51:49]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-08 12:51:58]

Patchset 2 (id:??) landed as
https://crrev.com/6e6d956e1199d80e3e53739958d061b6a1c36fad
Cr-Commit-Position: refs/heads/master@{#28318}