Bug 156930 – ASSERT(m_stack.last().isTailDeleted) at ShadowChicken.cpp:127 inspecting the inspector

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Joseph Pecoraro]

* SUMMARY
Assertion when inspecting the inspector.

* STEPS TO REPRODUCE
1. $ defaults write com.apple.Safari WebKitDebugDeveloperExtrasEnabled -bool YES
2. $ run-safari --debug
3. Inspect about:blank
4. Inspect the inspector (Right Click on the toolbar and select Inspect Element)
5. inspector²: Open DebuggerObserver.js
6. inspector²: Set a breakpoint in globalObjectCleared
7. inspector¹: Reload the page => triggers breakpoint in inspector²
8. inspector²: Continue
9. Repeat steps 7 and 8 if needed
  => ASSERT

* ASSERT
ASSERTION FAILED: !m_stack.last().isTailDeleted
/Users/pecoraro/Code/safari/OpenSource/Source/JavaScriptCore/interpreter/ShadowChicken.cpp(127) : void JSC::ShadowChicken::update(JSC::VM &, JSC::ExecState *)
1   0x10a158130 WTFCrash
2   0x109cc6045 JSC::ShadowChicken::update(JSC::VM&, JSC::ExecState*)
3   0x109ba2723 operationProcessShadowChickenLog
4   0x54ddab59107d
5   0x54ddab5aa6bf
6   0x54ddab8f9295
7   0x54ddab573005
8   0x54ddab573026
9   0x54ddab573026
10  0x54ddab573026
11  0x54ddab573026
12  0x109d8311f llint_entry
13  0x109d83199 llint_entry
14  0x109d83199 llint_entry
15  0x109d83199 llint_entry
16  0x109d83199 llint_entry
17  0x109d7c65e vmEntryToJavaScript
18  0x109b8bdea JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*)
19  0x109b1f1cc JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
20  0x1093fc28e JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
21  0x109bdf4d2 JSC::boundFunctionCall(JSC::ExecState*)
22  0x54ddab401028
23  0x109d83199 llint_entry
24  0x109d83199 llint_entry
25  0x109d7c65e vmEntryToJavaScript
26  0x109b8bdea JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*)
27  0x109b1f1cc JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
28  0x1093fc28e JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
29  0x109a3e4f5 JSC::callSetter(JSC::ExecState*, JSC::JSValue, JSC::JSValue, JSC::JSValue, JSC::ECMAMode)
30  0x109c9622f JSC::JSObject::putInlineSlow(JSC::ExecState*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&)
31  0x109ba52e8 JSC::JSObject::putInline(JSC::JSCell*, JSC::ExecState*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&)
ERROR: Exiting process early due to unacknowledged closed-connection

[Filip Pizlo]

I think that this may be a bad assertion.  I will look.

[Filip Pizlo]

I think I have a fix.

[Filip Pizlo]

JoePeck confirmed that my fix works for him and he reviewed it.  I am running all of the tests.

[Filip Pizlo]

Created attachment 277101 [details]
patch for EWS

If EWS and my tests are happy then I'll land this, with a ChangeLog of course.

[Filip Pizlo]

Landed in http://trac.webkit.org/changeset/199918