[compiler] Make Compiler::EnsureBytecode not switch tiers.

[compiler] Make Compiler::EnsureBytecode not switch tiers.

This preserves the original shared code of the underlying function when
bytecode is provided. The method in question should only ensure bytecode
is present, but should avoid switching compilation tiers of the given
function. It might be that the function was fast-tracked to baseline by
inlining without going through the interpreted tier first.

R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-crbug-635923
BUG=chromium:635923
Committed: https://crrev.com/b52aecac7e1f05ec3a23c9732ae936a6e50252fc
Cr-Commit-Position: refs/heads/master@{#38866}

[Michael Starzinger, 2016-08-24 12:50:22]

The CQ bit was checked by mstarzinger@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-24 12:50:32]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-24 13:24:59]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-24 13:25:00]

Dry run: This issue passed the CQ dry run.

[rmcilroy, 2016-08-24 13:31:34]

LGTM, thanks.

https://codereview.chromium.org/2278543002/diff/1/src/compiler.cc
File src/compiler.cc (right):

https://codereview.chromium.org/2278543002/diff/1/src/compiler.cc#newcode1398
src/compiler.cc:1398: if (original_code->kind() == Code::FUNCTION) {
A comment might be good here.

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
File test/mjsunit/regress/regress-crbug-635923.js (right):

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-635923.js:5: // Flags: --allow-natives-syntax
--ignition --turbo-from-bytecode --turbo-filter=f
should this be --ignition-staging, or is --ignition enough?

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-635923.js:19: // Optimize {f} with TruboFan,
after it has been inlined.
/s/TruboFan/Turbofan

[Michael Starzinger, 2016-08-24 13:41:50]

The CQ bit was checked by mstarzinger@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-24 13:41:51]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Michael Starzinger, 2016-08-24 13:42:35]

Thanks! Addressed comments. Landing.

https://codereview.chromium.org/2278543002/diff/1/src/compiler.cc
File src/compiler.cc (right):

https://codereview.chromium.org/2278543002/diff/1/src/compiler.cc#newcode1398
src/compiler.cc:1398: if (original_code->kind() == Code::FUNCTION) {
On 2016/08/24 13:31:34, rmcilroy wrote:
> A comment might be good here.

Done.

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
File test/mjsunit/regress/regress-crbug-635923.js (right):

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-635923.js:5: // Flags: --allow-natives-syntax
--ignition --turbo-from-bytecode --turbo-filter=f
On 2016/08/24 13:31:34, rmcilroy wrote:
> should this be --ignition-staging, or is --ignition enough?

The "--ignition --turbo-from-bytecode" combination is enough.

https://codereview.chromium.org/2278543002/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-635923.js:19: // Optimize {f} with TruboFan,
after it has been inlined.
On 2016/08/24 13:31:34, rmcilroy wrote:
> /s/TruboFan/Turbofan

Done.

[commit-bot: I haz the power, 2016-08-24 14:05:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-24 14:05:10]

Dry run: This issue passed the CQ dry run.

[Michael Starzinger, 2016-08-24 14:07:10]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2016-08-24 14:07:10]

The patchset sent to the CQ was uploaded after l-g-t-m from
rmcilroy@chromium.org
Link to the patchset: https://codereview.chromium.org/2278543002/#ps20001
(title: "Addressed comments.")

[commit-bot: I haz the power, 2016-08-24 14:07:19]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-24 14:09:40]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-08-24 14:10:09]

Description was changed from

==========
[compiler] Make Compiler::EnsureBytecode not switch tiers.

This preserves the original shared code of the underlying function when
bytecode is provided. The method in question should only ensure bytecode
is present, but should avoid switching compilation tiers of the given
function. It might be that the function was fast-tracked to baseline by
inlining without going through the interpreted tier first.

R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-crbug-635923
BUG=chromium:635923
==========

to

==========
[compiler] Make Compiler::EnsureBytecode not switch tiers.

This preserves the original shared code of the underlying function when
bytecode is provided. The method in question should only ensure bytecode
is present, but should avoid switching compilation tiers of the given
function. It might be that the function was fast-tracked to baseline by
inlining without going through the interpreted tier first.

R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-crbug-635923
BUG=chromium:635923

Committed: https://crrev.com/b52aecac7e1f05ec3a23c9732ae936a6e50252fc
Cr-Commit-Position: refs/heads/master@{#38866}
==========

[commit-bot: I haz the power, 2016-08-24 14:10:10]

Patchset 2 (id:??) landed as
https://crrev.com/b52aecac7e1f05ec3a23c9732ae936a6e50252fc
Cr-Commit-Position: refs/heads/master@{#38866}