[turbofan] Replace information about uses by UseInfo in representation selection.

[turbofan] Replace information about uses by explicit truncation in representation selection.

This change replaces the bitwise masking of uses by storing the most general truncation for all uses.

Committed: https://crrev.com/9564ffe9c16485e77e9bcaec2aa36be8ed1f16ef
Cr-Commit-Position: refs/heads/master@{#32248}

[Jarin, 2015-11-24 15:20:50]

Description was changed from

==========
[turbofan] Replace information about uses by UseInfo in representation
selection.
==========

to

==========
[turbofan] Replace information about uses by explicit truncation in
representation selection.

This change replaces the bitwise masking of uses by storing the most general
truncation for all uses.
==========

[Jarin, 2015-11-24 15:20:50]

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

[Jarin, 2015-11-24 15:21:43]

Could you take a look, please?

[Benedikt Meurer, 2015-11-25 04:50:39]

I love this! This is probably the first time that I can say I'm able to read and
understand (some of) representation selection. Thanks for the cleanup.

LGTM with comment/nit.

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/representa...
File src/compiler/representation-change.h (right):

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/representa...
src/compiler/representation-change.h:19: class Truncation {
Nit: Add final. 
Can we perhaps move the implementation of the RepresentationChanger to a .cc
file? This "everything in .h" approach doesn't scale too well.

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/simplified...
File src/compiler/simplified-lowering.cc (right):

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/simplified...
src/compiler/simplified-lowering.cc:181: bool queued_ = false;                 
// Bookkeeping for the traversal.
Awesome!

https://codereview.chromium.org/1464763003/diff/80001/test/cctest/compiler/te...
File test/cctest/compiler/test-representation-change.cc (right):

https://codereview.chromium.org/1464763003/diff/80001/test/cctest/compiler/te...
test/cctest/compiler/test-representation-change.cc:455: // TODO(titzer): assume
that uses of a word32 without a sign mean kTypeInt32.
This comment seems to be wrong/useless. Can we remove that?

[Jarin, 2015-11-25 06:39:53]

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/representa...
File src/compiler/representation-change.h (right):

https://codereview.chromium.org/1464763003/diff/80001/src/compiler/representa...
src/compiler/representation-change.h:19: class Truncation {
On 2015/11/25 04:50:39, Benedikt Meurer wrote:
> Nit: Add final. 
> Can we perhaps move the implementation of the RepresentationChanger to a .cc
> file? This "everything in .h" approach doesn't scale too well.

Maybe. The header is only included in simplified-lowering.cc, so it is not a big
problem (yet).

Will do in a separate CL.

https://codereview.chromium.org/1464763003/diff/80001/test/cctest/compiler/te...
File test/cctest/compiler/test-representation-change.cc (right):

https://codereview.chromium.org/1464763003/diff/80001/test/cctest/compiler/te...
test/cctest/compiler/test-representation-change.cc:455: // TODO(titzer): assume
that uses of a word32 without a sign mean kTypeInt32.
On 2015/11/25 04:50:39, Benedikt Meurer wrote:
> This comment seems to be wrong/useless. Can we remove that?

Done.

[Jarin, 2015-11-25 07:39:31]

The CQ bit was checked by jarin@chromium.org

[Jarin, 2015-11-25 07:39:31]

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/1464763003/#ps120001
(title: "final goodness")

[commit-bot: I haz the power, 2015-11-25 07:39:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1464763003/120001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1464763003/120001

[commit-bot: I haz the power, 2015-11-25 08:00:55]

Committed patchset #7 (id:120001)

[commit-bot: I haz the power, 2015-11-25 08:01:08]

Patchset 7 (id:??) landed as
https://crrev.com/9564ffe9c16485e77e9bcaec2aa36be8ed1f16ef
Cr-Commit-Position: refs/heads/master@{#32248}