[turbofan] move optimizer - CompressBlock cleanup

[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.

BUG=

Committed: https://crrev.com/3f7e96df21c251d7120c0ae86248406878158afe
Cr-Commit-Position: refs/heads/master@{#33016}

[Mircea Trofin, 2015-12-23 04:53:27]

Description was changed from

==========
[turbofan] move optimizer - CompressBlock cleanup

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

to

==========
[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.
 
BUG=
==========

[Mircea Trofin, 2015-12-23 04:53:28]

mtrofin@chromium.org changed reviewers:
+ bmeurer@chromium.org, jarin@chromium.org

[Benedikt Meurer, 2015-12-23 04:55:47]

LGTM.

[Mircea Trofin, 2015-12-23 04:58:02]

The CQ bit was checked by mtrofin@chromium.org

[commit-bot: I haz the power, 2015-12-23 04:58:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1543973002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1543973002/1

[commit-bot: I haz the power, 2015-12-23 04:59:13]

Description was changed from

==========
[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.
 
BUG=
==========

to

==========
[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.
 
BUG=
==========

[commit-bot: I haz the power, 2015-12-23 04:59:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-23 04:59:34]

Description was changed from

==========
[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.
 
BUG=
==========

to

==========
[turbofan] move optimizer - CompressBlock cleanup.

I believe the code reads easier after this change. The original code
probably dates back to when we had 4 gap positions. Now that there
are only 2, the logic can be simpler by avoiding a loop and instead
treating each case explicitly: no gaps; gaps just at end; gaps at start and
maybe end. That way, it is also  easier to understand how the moves get
pushed downwards. This is what got me to make this change in the first
place: trying to work out a finer grained move optimization.

BUG=

Committed: https://crrev.com/3f7e96df21c251d7120c0ae86248406878158afe
Cr-Commit-Position: refs/heads/master@{#33016}
==========

[commit-bot: I haz the power, 2015-12-23 04:59:35]

Patchset 1 (id:??) landed as
https://crrev.com/3f7e96df21c251d7120c0ae86248406878158afe
Cr-Commit-Position: refs/heads/master@{#33016}