[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

This allows us to get rid of the "push TruncateFloat64ToInt32 into Phi"
trick that was used in the MachineOperatorReducer to combine the
ChangeTaggedToFloat64 and TruncateFloat64ToInt32 operations. Instead of
doing that later, we can just introduce the proper operator during the
representation selection directly.

Also separate the TruncateFloat64ToInt32 machine operator, which had two
different meanings depending on a flag (either JavaScript truncation or
C++ style round to zero). Now there's a TruncateFloat64ToWord32 which
represents the JavaScript truncation (implemented via TruncateDoubleToI
macro + code stub) and the RoundFloat64ToInt32, which implements the C++
round towards zero operation (in the same style as the other WebAssembly
driven Round* machine operators).

R=jarin@chromium.org

Committed: https://crrev.com/0231a7efa2b5ce8108a837284e2f63dccd5dcd09
Cr-Commit-Position: refs/heads/master@{#35743}

[Benedikt Meurer, 2016-04-22 19:46:26]

Hey Jaro,

Here's the next cleanup step, finally getting rid of this weird pushing into
Phi.
Please take a look.

Thanks,
Benedikt

[Jarin, 2016-04-24 09:22:50]

lgtm

https://codereview.chromium.org/1919513002/diff/1/src/compiler/change-lowerin...
File src/compiler/change-lowering.cc (right):

https://codereview.chromium.org/1919513002/diff/1/src/compiler/change-lowerin...
src/compiler/change-lowering.cc:403: if
(NodeProperties::GetType(value)->Maybe(Type::Undefined())) {
Just a note: We will have to provide a hint for this at some point. It is also
possible that in future we will want to support more oddballs here (null, true,
false). Maybe a TODO here?

[Benedikt Meurer, 2016-04-24 11:11:50]

On 2016/04/24 09:22:50, Jarin wrote:
> lgtm
> 
>
https://codereview.chromium.org/1919513002/diff/1/src/compiler/change-lowerin...
> File src/compiler/change-lowering.cc (right):
> 
>
https://codereview.chromium.org/1919513002/diff/1/src/compiler/change-lowerin...
> src/compiler/change-lowering.cc:403: if
> (NodeProperties::GetType(value)->Maybe(Type::Undefined())) {
> Just a note: We will have to provide a hint for this at some point. It is also
> possible that in future we will want to support more oddballs here (null,
true,
> false). Maybe a TODO here?

Well, this applies to all uses of Type* in lowering of ChangeTaggedToFoo; I plan
to introduce a TaggedInputHint that can also be used to eliminate the smi check.

[Benedikt Meurer, 2016-04-24 11:11:58]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-04-24 11:12:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1919513002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1919513002/1

[commit-bot: I haz the power, 2016-04-24 11:39:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-24 11:41:32]

Description was changed from

==========
[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

This allows us to get rid of the "push TruncateFloat64ToInt32 into Phi"
trick that was used in the MachineOperatorReducer to combine the
ChangeTaggedToFloat64 and TruncateFloat64ToInt32 operations. Instead of
doing that later, we can just introduce the proper operator during the
representation selection directly.

Also separate the TruncateFloat64ToInt32 machine operator, which had two
different meanings depending on a flag (either JavaScript truncation or
C++ style round to zero). Now there's a TruncateFloat64ToWord32 which
represents the JavaScript truncation (implemented via TruncateDoubleToI
macro + code stub) and the RoundFloat64ToInt32, which implements the C++
round towards zero operation (in the same style as the other WebAssembly
driven Round* machine operators).

R=jarin@chromium.org
==========

to

==========
[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

This allows us to get rid of the "push TruncateFloat64ToInt32 into Phi"
trick that was used in the MachineOperatorReducer to combine the
ChangeTaggedToFloat64 and TruncateFloat64ToInt32 operations. Instead of
doing that later, we can just introduce the proper operator during the
representation selection directly.

Also separate the TruncateFloat64ToInt32 machine operator, which had two
different meanings depending on a flag (either JavaScript truncation or
C++ style round to zero). Now there's a TruncateFloat64ToWord32 which
represents the JavaScript truncation (implemented via TruncateDoubleToI
macro + code stub) and the RoundFloat64ToInt32, which implements the C++
round towards zero operation (in the same style as the other WebAssembly
driven Round* machine operators).

R=jarin@chromium.org

Committed: https://crrev.com/0231a7efa2b5ce8108a837284e2f63dccd5dcd09
Cr-Commit-Position: refs/heads/master@{#35743}
==========

[commit-bot: I haz the power, 2016-04-24 11:41:33]

Patchset 1 (id:??) landed as
https://crrev.com/0231a7efa2b5ce8108a837284e2f63dccd5dcd09
Cr-Commit-Position: refs/heads/master@{#35743}