[turbofan] Perform element index computation in word64 on 64-bit platforms.

[turbofan] Perform element index computation in word64 on 64-bit platforms.

This allows us to fuse the address computation with the actual memory
access operation on x64, which reduces the register pressure and the
number of instructions. There's probably some follow up cleanup that has
to happen to make sure the machine operator optimizations that are
relevant to word64 computations are also available (similar to what is
already available for word32).

R=epertoso@chromium.org

Committed: https://crrev.com/5d2d46e3880063269e84234d9e10fff7ab8f3997
Cr-Commit-Position: refs/heads/master@{#38051}

[Benedikt Meurer, 2016-07-26 12:53:43]

The CQ bit was checked by bmeurer@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-26 12:53:49]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Benedikt Meurer, 2016-07-26 12:55:02]

Hey Enrico,

Here's a simple change to make the pesky leal's go away on x64.
Please take a look.

Thanks,
Benedikt

[Benedikt Meurer, 2016-07-26 12:56:45]

The CQ bit was unchecked by bmeurer@chromium.org

[epertoso, 2016-07-26 12:57:21]

lgtm

[Benedikt Meurer, 2016-07-26 12:57:30]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-07-26 12:57:40]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-26 13:13:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-26 13:14:11]

Description was changed from

==========
[turbofan] Perform element index computation in word64 on 64-bit platforms.

This allows us to fuse the address computation with the actual memory
access operation on x64, which reduces the register pressure and the
number of instructions. There's probably some follow up cleanup that has
to happen to make sure the machine operator optimizations that are
relevant to word64 computations are also available (similar to what is
already available for word32).

R=epertoso@chromium.org
==========

to

==========
[turbofan] Perform element index computation in word64 on 64-bit platforms.

This allows us to fuse the address computation with the actual memory
access operation on x64, which reduces the register pressure and the
number of instructions. There's probably some follow up cleanup that has
to happen to make sure the machine operator optimizations that are
relevant to word64 computations are also available (similar to what is
already available for word32).

R=epertoso@chromium.org

Committed: https://crrev.com/5d2d46e3880063269e84234d9e10fff7ab8f3997
Cr-Commit-Position: refs/heads/master@{#38051}
==========

[commit-bot: I haz the power, 2016-07-26 13:14:12]

Patchset 1 (id:??) landed as
https://crrev.com/5d2d46e3880063269e84234d9e10fff7ab8f3997
Cr-Commit-Position: refs/heads/master@{#38051}