Bug 197552

Summary:

[JSC] Generator CodeBlock generation should be idempotent

Product:

WebKit

Reporter:

Yusuke Suzuki <ysuzuki>

Component:

JavaScriptCore

Assignee:

Yusuke Suzuki <ysuzuki>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

ews-watchlist, keith_miller, mark.lam, msaboff, rniwa, saam, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Patch	none
Archive of layout-test-results from ews101 for mac-highsierra	none
Archive of layout-test-results from ews107 for mac-highsierra-wk2	none
Patch	keith_miller: review+

Description Yusuke Suzuki 2019-05-02 23:52:52 PDT

ES6 Generator can save the execution state inside an object.
When the underlying CodeBlock is jettisoned and generated again, if the CodeBlock content is different, resume becomes totally broken!
e.g. regenerating CodeBlock with Debugger.

Comment 1 Yusuke Suzuki 2019-05-02 23:54:40 PDT

<rdar://problem/48538201>

Comment 2 Yusuke Suzuki 2019-05-03 01:28:54 PDT

Created attachment 368915 [details]
Patch

Comment 3 EWS Watchlist 2019-05-03 02:38:44 PDT

Comment on attachment 368915 [details]
Patch

Attachment 368915 [details] did not pass mac-ews (mac):
Output: https://webkit-queues.webkit.org/results/12082656

Number of test failures exceeded the failure limit.

Comment 4 EWS Watchlist 2019-05-03 02:38:46 PDT

Created attachment 368917 [details]
Archive of layout-test-results from ews101 for mac-highsierra

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: ews101  Port: mac-highsierra  Platform: Mac OS X 10.13.6

Comment 5 EWS Watchlist 2019-05-03 02:49:08 PDT

Comment on attachment 368915 [details]
Patch

Attachment 368915 [details] did not pass mac-wk2-ews (mac-wk2):
Output: https://webkit-queues.webkit.org/results/12082694

Number of test failures exceeded the failure limit.

Comment 6 EWS Watchlist 2019-05-03 02:49:10 PDT

Created attachment 368918 [details]
Archive of layout-test-results from ews107 for mac-highsierra-wk2

The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews.
Bot: ews107  Port: mac-highsierra-wk2  Platform: Mac OS X 10.13.6

Comment 7 Yusuke Suzuki 2019-05-03 03:02:23 PDT

Created attachment 368919 [details]
Patch

Comment 8 Yusuke Suzuki 2019-05-03 11:37:48 PDT

Comment on attachment 368919 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=368919&action=review

> Source/JavaScriptCore/ChangeLog:28
> +           and pass them as a parameter, OptionSet<CodeGeneratorMode>.

Note that each created Generator holds JSFunction to the generator body. So state & ScriptExecutable is always tightly coupled. Storing CodeGeneratorMode in ScriptExecutable allows us to regenerate the same CodeBlock for that if the generator is created before the debugger is enabled.

Comment 9 Keith Miller 2019-05-03 11:51:29 PDT

Comment on attachment 368919 [details]
Patch

r=me.

Comment 10 Yusuke Suzuki 2019-05-03 11:54:50 PDT

Committed r244915: <https://trac.webkit.org/changeset/244915>

Comment 11 Saam Barati 2019-05-13 12:24:06 PDT

Comment on attachment 368919 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=368919&action=review

> Source/JavaScriptCore/runtime/ScriptExecutable.cpp:318
> +    // We continue using the same CodeGenerationMode for Generators because live generator objects can
> +    // keep the state which is only valid with the CodeBlock compiled with the same CodeGenerationMode.

So what happens when we enable the debugger? Will we never be able to pause on this generator then? Or will we be able to pause for new invocations?

It seems like this makes it so new invocations of the generator won't have debugging opcodes ever. Can we find a way to not make that the case?