Bug 124760

Summary:

Restructure global variable constant inference so that it could work for any kind of symbol table variable

Product:

WebKit

Reporter:

Filip Pizlo <fpizlo>

Component:

JavaScriptCore

Assignee:

Filip Pizlo <fpizlo>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

barraclough, ggaren, mark.lam, mhahnenberg, msaboff, oliver, sam

Priority:

Version:

528+ (Nightly build)

Hardware:

All

OS:

All

Bug Depends on:

124761

Bug Blocks:

124630

Attachments:

Description	Flags
work in progress	none
more things	none
the wrong approach	none
more	none
more	none
the patch	oliver: review+
patch for landing	none

Filip Pizlo

Reported 2013-11-21 21:29:11 PST

Patch forthcoming.

Attachments
work in progress (20.39 KB, patch) 2013-11-23 13:58 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
more things (40.92 KB, patch) 2013-11-23 15:15 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
the wrong approach (48.32 KB, patch) 2013-11-23 16:26 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
more (58.86 KB, patch) 2013-11-25 21:27 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
more (67.82 KB, patch) 2013-11-26 09:40 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
the patch (68.06 KB, patch) 2013-11-26 10:56 PST, Filip Pizlo	oliver: review+	Details Formatted Diff Diff
patch for landing (68.41 KB, patch) 2013-11-26 17:21 PST, Filip Pizlo	no flags	Details Formatted Diff Diff
Show Obsolete (6) View All Add attachment proposed patch, testcase, etc.

Filip Pizlo

Comment 1 2013-11-23 13:58:18 PST

Created attachment 217752 [details] work in progress

Filip Pizlo

Comment 2 2013-11-23 15:15:27 PST

Created attachment 217753 [details] more things

Oliver Hunt

Comment 3 2013-11-23 15:18:54 PST

Comment on attachment 217753 [details] more things View in context: https://bugs.webkit.org/attachment.cgi?id=217753&action=review > Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp:3100 > + JSValue specificValue = > + watchpointSet ? watchpointSet->inferredValue() : JSValue(); > + if (!specificValue) { JSValue specificValue; if (watchpointSet) specificValue = watchPointSet->inferredValue(); (can inferredValue here ever be JSValue()?)

Filip Pizlo

Comment 4 2013-11-23 15:20:39 PST

(In reply to comment #3) > (From update of attachment 217753 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=217753&action=review > > > Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp:3100 > > + JSValue specificValue = > > + watchpointSet ? watchpointSet->inferredValue() : JSValue(); > > + if (!specificValue) { > > JSValue specificValue; > if (watchpointSet) > specificValue = watchPointSet->inferredValue(); (can inferredValue here ever be JSValue()?) That would be wrong, since watchpointSet->inferredValue() can be JSValue().

Filip Pizlo

Comment 5 2013-11-23 16:17:19 PST

Actually, this whole approach is wrong. Consider this: function foo() { var WIDTH; function bar() { ... use WIDTH ... } WIDTH = 42; ... use bar } 1) Unless we do some static analysis we can't be sure that bar will be called after "WIDTH = 42". 2) op_enter is technically an assignment to WIDTH.

Filip Pizlo

Comment 6 2013-11-23 16:26:48 PST

Created attachment 217755 [details] the wrong approach This is the wrong approach but I wanted to set aside the code anyway.

Filip Pizlo

Comment 7 2013-11-25 21:27:06 PST

Actually, I think we totally want this. It'll work when combined with one-shot closure inference.

Filip Pizlo

Comment 8 2013-11-25 21:27:51 PST

Created attachment 217861 [details] more

Filip Pizlo

Comment 9 2013-11-26 09:40:07 PST

Created attachment 217883 [details] more