Bug 127566 – fast/profiler tests ASSERTing after moving recompileAllJSFunctions off a timer

• Component: WebCore JavaScript
• Status: RESOLVED FIXED

[Joseph Pecoraro]

http://build.webkit.org/results/Apple%20Mavericks%20Debug%20WK1%20(Tests)/r162690%20(2192)/results.html

Another internal method causing recompilation within a JS stack:

    window.internals.setJavaScriptProfilingEnabled(bool)

This Enables/Disables the Profiler which now recompiles synchronously within a JS stack. I can add a timer here in window.internals and do this after a loop. But its looking more and more like it might be better if the VM handled recompiling when appropriate instead of us trying to avoid calling it within a JS stack.

[Geoffrey Garen]

OK.

[Joseph Pecoraro]

Created attachment 222128 [details]
[PATCH] Naive Approach - Does not work running multiple tests

The naive approach of just making window.internals.setJavaScriptProfilerEnabled did not work.

    shell> Tools/Scripts/run-webkit-tests --debug fast/profiler/anonymous-event-handler.html
    PASS

    shell> Tools/Scripts/run-webkit-tests --debug fast/profiler/anonymous-event-handler.html --iterations=2
    FAILs

I could spend some more time looking into this, but we've already tried to work around it twice. I think it might be better for the JSC VM to handle recompiling when appropriate. No timers involved.

[Joseph Pecoraro]

> The naive approach of just making window.internals.setJavaScriptProfilerEnabled did not work.

window.internals.setJavaScriptProfilerEnabled *use a timer* did not work.

[Joseph Pecoraro]

Created attachment 222131 [details]
[PATCH] Proposed Fix - Let the VM manage recompilation

Suggestions on how I should measure the performance of this?

[Oliver Hunt]

Comment on attachment 222131 [details]
[PATCH] Proposed Fix - Let the VM manage recompilation

View in context: https://bugs.webkit.org/attachment.cgi?id=222131&action=review

> Source/JavaScriptCore/runtime/VMEntryScope.cpp:66
> +    if (UNLIKELY(m_recompilationNeeded)) {

You can't do this unless .entryScope is null.  Otherwise you have to set the parent's entry scope recompile flag.

[Joseph Pecoraro]

Comment on attachment 222131 [details]
[PATCH] Proposed Fix - Let the VM manage recompilation

View in context: https://bugs.webkit.org/attachment.cgi?id=222131&action=review

>> Source/JavaScriptCore/runtime/VMEntryScope.cpp:66
>> +    if (UNLIKELY(m_recompilationNeeded)) {
> 
> You can't do this unless .entryScope is null.  Otherwise you have to set the parent's entry scope recompile flag.

The next line ASSERTs that.

[Joseph Pecoraro]

Created attachment 222134 [details]
[PATCH] Proposed Fix - Let VM manage recompilation

More straightforward approach, instead of just adjusting the topEntryScope.

[Joseph Pecoraro]

Landed <http://trac.webkit.org/changeset/162720>.