DBC: Handle constants correctly in the optimizing backend

DBC: Handle constants correctly in the optimizing backend

We don't always allocate a register for constants in optimized code. Instead
they are copied into registes as needed by parallel moves at the use site.

Fixes #27731.

R=vegorov@google.com

Committed: https://github.com/dart-lang/sdk/commit/44418359e06c3af2305162ae8126d4632df37121

[Florian Schneider, 2016-11-03 10:33:58]

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

[Vyacheslav Egorov (Google), 2016-11-03 11:11:50]

lgtm

https://codereview.chromium.org/2477653002/diff/1/runtime/vm/intermediate_lan...
File runtime/vm/intermediate_language_dbc.cc (right):

https://codereview.chromium.org/2477653002/diff/1/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language_dbc.cc:341: if (compiler->is_optimizing() &&
locs()->out(0).IsRegister()) {
We will end up Pushing the constant on the stack here.

Maybe you wanted to do:

if (... is_optimizing()) {
  if (... IsRegister()) {
  }
} else ...

Instead?

[Florian Schneider, 2016-11-03 11:23:00]

https://codereview.chromium.org/2477653002/diff/1/runtime/vm/intermediate_lan...
File runtime/vm/intermediate_language_dbc.cc (right):

https://codereview.chromium.org/2477653002/diff/1/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language_dbc.cc:341: if (compiler->is_optimizing() &&
locs()->out(0).IsRegister()) {
On 2016/11/03 11:11:50, Vyacheslav Egorov (Google) wrote:
> We will end up Pushing the constant on the stack here.
> 
> Maybe you wanted to do:
> 
> if (... is_optimizing()) {
>   if (... IsRegister()) {
>   }
> } else ...
> 
> Instead?

Done. Yes, of course. I simplfified the code incorrectly somehow.

[Florian Schneider, 2016-11-03 11:24:11]

Description was changed from

==========
DBC: Handle constants correctly in the optimizing backend

We don't always allocate a register for constants in optimized code. Instead
they are copied into registes as needed by parallel moves at the use site.

Fixes #27731.
==========

to

==========
DBC: Handle constants correctly in the optimizing backend

We don't always allocate a register for constants in optimized code. Instead
they are copied into registes as needed by parallel moves at the use site.

Fixes #27731.

R=vegorov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/44418359e06c3af2305162ae8126d4632df37121
==========

[Florian Schneider, 2016-11-03 11:24:12]

Committed patchset #2 (id:20001) manually as
44418359e06c3af2305162ae8126d4632df37121 (presubmit successful).