Reland "VM: Handle null-comparisons in the flow graph type propagation"

Reland "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 30a942f7287e67d4bcf43f2959428033612b1a70.

Plus:

1. Fixes integer type propagation in the optimizer by introducing a _int64 marker interface

2. Fixes calculation of whether an instructions can deoptimize: This has to be stable so that
once determined that an instructions can't deoptimize, it will stay that way and not flip back
later in the optimization

3. Address comments to improve CompileType::CopyNonNullable()

R=vegorov@google.com

Committed: https://github.com/dart-lang/sdk/commit/e7afde47e9afc981e9609ea14770debc18479bb1

[Florian Schneider, 2017-03-29 20:47:28]

fschneider@google.com changed reviewers:
+ vegorov@google.com

[Florian Schneider, 2017-03-29 20:47:28]

Not for landing yet.

I added regression tests and a quick fix for ia32 only. Let's discuss offline
how to proceed.

[Florian Schneider, 2017-03-30 22:09:14]

Ready for review

[Vyacheslav Egorov (Google), 2017-03-31 10:39:44]

LGTM

I think we could have made _int64 purely a CompileType without an underlying
real class/type - but we can do this as cleanup later.

https://codereview.chromium.org/2772143002/diff/100001/runtime/lib/integers.dart
File runtime/lib/integers.dart (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/lib/integers.d...
runtime/lib/integers.dart:5: abstract class _int64 implements int {}
Please add a comment about the reason to have this class.

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/flow_graph_...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/flow_graph_...
runtime/vm/flow_graph_type_propagator.cc:795: if (value()->Type()->ToCid() !=
kDynamicCid) {
Should this and below be ToNullableCid()?

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/intermediat...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/intermediat...
runtime/vm/intermediate_language.h:603: virtual bool ComputeCanDeoptimize()
const = 0;
Maybe add a comment here that it is not currently sticky and might change as
graph is changed because we sometimes loose information (e.g. remove
redefinitions).

[Florian Schneider, 2017-03-31 16:39:31]

https://codereview.chromium.org/2772143002/diff/100001/runtime/lib/integers.dart
File runtime/lib/integers.dart (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/lib/integers.d...
runtime/lib/integers.dart:5: abstract class _int64 implements int {}
On 2017/03/31 10:39:44, Vyacheslav Egorov (Google) wrote:
> Please add a comment about the reason to have this class.

Done.

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/flow_graph_...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/flow_graph_...
runtime/vm/flow_graph_type_propagator.cc:795: if (value()->Type()->ToCid() !=
kDynamicCid) {
On 2017/03/31 10:39:44, Vyacheslav Egorov (Google) wrote:
> Should this and below be ToNullableCid()?

I think you're right because we have nullability information explicit anyway.

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/intermediat...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/2772143002/diff/100001/runtime/vm/intermediat...
runtime/vm/intermediate_language.h:603: virtual bool ComputeCanDeoptimize()
const = 0;
On 2017/03/31 10:39:44, Vyacheslav Egorov (Google) wrote:
> Maybe add a comment here that it is not currently sticky and might change as
> graph is changed because we sometimes loose information (e.g. remove
> redefinitions).

Done.

[Florian Schneider, 2017-03-31 17:13:04]

Description was changed from

==========
Reland "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 30a942f7287e67d4bcf43f2959428033612b1a70.

Plus:

1. Fixes integer type propagation in the optimizer by introducing a _int64
marker interface

2. Fixes calculation of whether an instructions can deoptimize: This has to be
stable so that
once determined that an instructions can't deoptimize, it will stay that way and
not flip back
later in the optimization

3. Address comments to improve CompileType::CopyNonNullable()
==========

to

==========
Reland "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 30a942f7287e67d4bcf43f2959428033612b1a70.

Plus:

1. Fixes integer type propagation in the optimizer by introducing a _int64
marker interface

2. Fixes calculation of whether an instructions can deoptimize: This has to be
stable so that
once determined that an instructions can't deoptimize, it will stay that way and
not flip back
later in the optimization

3. Address comments to improve CompileType::CopyNonNullable()

R=vegorov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/e7afde47e9afc981e9609ea14770debc18479bb1
==========

[Florian Schneider, 2017-03-31 17:13:06]

Committed patchset #7 (id:120001) manually as
e7afde47e9afc981e9609ea14770debc18479bb1 (presubmit successful).

[Florian Schneider, 2017-03-31 20:54:40]

Patchset #8 (id:140001) has been deleted