Steps to reproduce: 1. Use an engineering build which has WEB_REPLAY enabled. 2. Navigate to the page 3. Open the web inspector 4. Open the timelines sidebar panel 5. Right-click on the navigation bar and select "Show Replay Controls" 6. Press the recording button (centered) After recording for a few (5-10) seconds, the inspector crashes. This is very reproducible on this page. I am currently trying to narrow down the reproduction steps, as it is probably triggered by the timelines overview, not anything specific to WEB_REPLAY. I will update this bug if a debug build/lldb hits any useful asserts. Stack trace: 1 0x1119bba6a JSC::repatchCall(JSC::RepatchBuffer&, JSC::CodeLocationCall, JSC::FunctionPtr) 2 0x1119ba7e8 JSC::repatchIn(JSC::ExecState*, JSC::JSCell*, JSC::Identifier const&, bool, JSC::PropertySlot const&, JSC::StructureStubInfo&) 3 0x11181efa9 operationInOptimize 4 0x3b491b3df194 5 0x1118f64f9 callToJavaScript 6 0x111803093 JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) 7 0x1117e86ea JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 8 0x1115cc55e JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 9 0x1117b1f39 JSC::callGetter(JSC::ExecState*, JSC::JSValue, JSC::JSValue) 10 0x11181ddcd operationGetById 11 0x3b491b416934 12 0x3b491b45ae57 13 0x3b491b492882 14 0x3b491b48e66e 15 0x3b491b36a8c7 16 0x1118f64f9 callToJavaScript 17 0x111803093 JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) 18 0x1117e86ea JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 19 0x1115cc55e JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 20 0x11184c33b JSC::boundFunctionCall(JSC::ExecState*) 21 0x1118f6697 callToNativeFunction 22 0x1117e8730 JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 23 0x1115cc5af JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, JSC::JSValue*) 24 0x11235ab14 WebCore::JSCallbackData::invokeCallback(JSC::JSValue, JSC::MarkedArgumentBuffer&, bool*) 25 0x1125491cf WebCore::JSRequestAnimationFrameCallback::handleEvent(double) 26 0x11292e387 WebCore::ScriptedAnimationController::serviceScriptedAnimations(double) 27 0x111fda27b WebCore::DisplayRefreshMonitor::displayDidRefresh() 28 0x111a50b94 WTF::dispatchFunctionsFromMainThread() 29 0x7fff9390d13e __NSThreadPerformPerform 30 0x7fff96b0e5b1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ 31 0x7fff96affc62 __CFRunLoopDoSources0
<rdar://problem/17988544>
Seems to not reproduce anymore. It may have been related to msaboff's fix yesterday.