Thank you Jakob! I can understand why it is hidden from external access. But would it be possible for the user to get access to the instruction addresses of the compiled code?
We are studying the cache performance of JavaScript execution and we want to know if it is possible to prefetch the instructions in the next event handlers into the cache before it is executed based on the information collected in the v8 engine. Best regards, On Tuesday, August 29, 2017 at 12:29:33 PM UTC-4, Jakob Kummerow wrote: > > No, compiled code is an internal implementation detail and as such is > hidden from JavaScript and other external access. If there ever is a way > for users to get to compiled code, then it's a (probably severe security) > bug and we would like to hear about it! :-) > > On Mon, Aug 28, 2017 at 9:03 PM, Hanyun Tao <taoha...@gmail.com > <javascript:>> wrote: > >> Hi Jakob, >> >> Thanks again! >> >> According to what you have said, v8 compiles the event handlers are >> installed(compiled?) before it is executed. If it is true, then I believe >> v8 will store the compiled code somewhere in the system. >> Would it be possible for the user to get access to the compiled code? >> >> Best regards, >> >> On Monday, August 28, 2017 at 1:29:29 PM UTC-4, Jakob Kummerow wrote: >>> >>> The main API entry point for compilation is >>> v8::ScriptCompiler::Compile(). >>> >>> I don't think event handling itself triggers compilation; but I'm not an >>> expert on that part of the system. AFAIK event handlers are installed >>> during page load (or more precisely: DOM element creation); they may still >>> be compiled on-demand on first use but that's not controlled via the V8 API. >>> >>> On Mon, Aug 28, 2017 at 9:06 AM, Hanyun Tao <taoha...@gmail.com> wrote: >>> >>>> Hi Jakob, >>>> >>>> Thank you for replying! >>>> >>>> To be more specific, I'm looking for the point (function) that initiate >>>> the compilation process. >>>> >>>> In my understanding, when handling an "event", the renderer process in >>>> the browser will figure out the JavaScript related to the event, and ask >>>> the V8 engine to execute it by calling some api function. >>>> >>>> Inside those api function, there should be a point where V8 initiate >>>> the compilation process, and that is what I'm looking for. >>>> >>>> Best regards, >>>> >>>> >>>> >>>> On Sunday, August 27, 2017 at 7:58:37 PM UTC-4, Jakob Kummerow wrote: >>>>> >>>>> Hi Hanyun, >>>>> >>>>> V8 is fairly complicated, and pretty much all it does is to compile >>>>> and execute JavaScript. Do you have a more specific question? >>>>> >>>>> If you just want a starting point for reading code: maybe >>>>> "CompileTopLevel" in src/compiler.cc would be a reasonable choice. >>>>> >>>>> On Sun, Aug 27, 2017 at 1:06 PM, Hanyun Tao <taoha...@gmail.com> >>>>> wrote: >>>>> >>>>>> Hi all, >>>>>> >>>>>> I'm trying to understand how V8 engine compiles and execute >>>>>> JavaScript events. I used GDB to track the function call path when >>>>>> handling >>>>>> an event and it look like this. >>>>>> >>>>>> >>>>>> >>>>>> #0 v8::internal::Logger::TimerEvent (this=<optimized out>, >>>>>> se=<optimized out>, name=<optimized out>) at ../../v8/src/log.cc:866 >>>>>> >>>>>> >>>>>> #1 0x00007f0cfcb23b39 in TimerEventScope (this=<optimized out>, >>>>>> isolate=<optimized out>) at ../../v8/src/log.h:354 >>>>>> >>>>>> >>>>>> #2 v8::Function::Call (this=<optimized out>, context=..., >>>>>> recv=..., argc=<optimized out>, argv=<optimized out>) at >>>>>> ../../v8/src/api.cc:5094 >>>>>> >>>>>> >>>>>> #3 0x00007f0cf18daa0b in blink::V8ScriptRunner::callFunction >>>>>> (function=..., context=0x201b099829d0, receiver=..., argc=1, >>>>>> args=0x7fffe9e1cea0, >>>>>> isolate=0x2def318c6020) at ../../third_party/WebKit/Source/ >>>>>> bindings/core/v8/V8ScriptRunner.cpp:658 >>>>>> >>>>>> >>>>>> #4 0x00007f0cf18a1c26 in >>>>>> blink::V8EventListener::callListenerFunction (this=0xe9381bfbea0, >>>>>> scriptState=0x37fa7244c710, jsEvent=..., event= >>>>>> 0x36f97e2ba60) at ../../third_party/WebKit/Source/bindings/core/ >>>>>> v8/V8EventListener.cpp:112 >>>>>> >>>>>> >>>>>> >>>>>> #5 0x00007f0cf1887b16 in >>>>>> blink::V8AbstractEventListener::invokeEventHandler (this=0xe9381bfbea0, >>>>>> scriptState=0x37fa7244c710, >>>>>> event=0x36f97e2ba60, jsEvent=...) at ../../third_party/WebKit/ >>>>>> Source/bindings/core/v8/V8AbstractEventListener.cpp:142 >>>>>> >>>>>> >>>>>> #6 0x00007f0cf188787f in >>>>>> blink::V8AbstractEventListener::handleEvent (this=0xe9381bfbea0, >>>>>> scriptState=0x37fa7244c710, event=0x36f97e2ba60) >>>>>> at ../../third_party/WebKit/Source/bindings/core/v8/ >>>>>> V8AbstractEventListener.cpp:101 >>>>>> >>>>>> >>>>>> #7 0x00007f0cf1887689 in >>>>>> blink::V8AbstractEventListener::handleEvent (this=0xe9381bfbea0, >>>>>> executionContext=0x201b099829d0, event=0x36f97e2ba60) >>>>>> at ../../third_party/WebKit/Source/bindings/core/v8/ >>>>>> V8AbstractEventListener.cpp:89 >>>>>> >>>>>> >>>>>> #8 0x00007f0cf211c596 in blink::EventTarget::fireEventListeners >>>>>> (this=0x201b09982858, event=0x36f97e2ba60, d=0xe9381be9500, entry=...) >>>>>> at ../../third_party/WebKit/Source/core/events/EventTarget.cpp: >>>>>> 700 >>>>>> >>>>>> >>>>>> #9 0x00007f0cf211b7cb in blink::EventTarget::fireEventListeners >>>>>> (this=0x201b09982858, event=0x36f97e2ba60) >>>>>> at ../../third_party/WebKit/Source/core/events/EventTarget.cpp:56 >>>>>> >>>>>> >>>>>> I tried to read the source code to find out where does V8 compiles >>>>>> the JavaScript, but unfortunately, I could not find it. >>>>>> >>>>>> It would be really helpful if someone can explain the process to me, >>>>>> or let me know which files(functions) I should read. >>>>>> >>>>>> Best regards, >>>>>> >>>>>> -- >>>>>> -- >>>>>> v8-users mailing list >>>>>> v8-u...@googlegroups.com >>>>>> http://groups.google.com/group/v8-users >>>>>> --- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "v8-users" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to v8-users+u...@googlegroups.com. >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- >>>> -- >>>> v8-users mailing list >>>> v8-u...@googlegroups.com >>>> http://groups.google.com/group/v8-users >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "v8-users" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to v8-users+u...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> -- >> v8-users mailing list >> v8-u...@googlegroups.com <javascript:> >> http://groups.google.com/group/v8-users >> --- >> You received this message because you are subscribed to the Google Groups >> "v8-users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to v8-users+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
