C++ (Cpp) JSScript::nativeCodeForPC示例

extern "C" void *
js_InternalThrow(VMFrame &f)
{
    JSContext *cx = f.cx;

    // It's possible that from within RunTracer(), Interpret() returned with
    // an error and finished the frame (i.e., called ScriptEpilogue), but has
    // not yet performed an inline return.
    //
    // In this case, RunTracer() has no choice but to propagate the error
    // up to the method JIT, and thus to this function. But ScriptEpilogue()
    // has already been called. Detect this, and avoid double-finishing the
    // frame. See HandleErrorInExcessFrame() and bug 624100.
    if (f.fp()->finishedInInterpreter()) {
        // If it's the last frame, just propagate the failure up again.
        if (f.fp() == f.entryfp)
            return NULL;

        InlineReturn(f);
    }

    // Make sure sp is up to date.
    JS_ASSERT(cx->regs == &f.regs);

    // Call the throw hook if necessary
    JSThrowHook handler = f.cx->debugHooks->throwHook;
    if (handler) {
        Value rval;
        switch (handler(cx, cx->fp()->script(), cx->regs->pc, Jsvalify(&rval),
                        cx->debugHooks->throwHookData)) {
          case JSTRAP_ERROR:
            cx->clearPendingException();
            return NULL;

          case JSTRAP_RETURN:
            cx->clearPendingException();
            cx->fp()->setReturnValue(rval);
            return JS_FUNC_TO_DATA_PTR(void *,
                   cx->jaegerCompartment()->forceReturnTrampoline());

          case JSTRAP_THROW:
            cx->setPendingException(rval);
            break;

          default:
            break;
        }
    }

    jsbytecode *pc = NULL;
    for (;;) {
        pc = FindExceptionHandler(cx);
        if (pc)
            break;

        // The JIT guarantees that ScriptEpilogue() has always been run
        // upon exiting to its caller. This is important for consistency,
        // where execution modes make similar guarantees about prologues
        // and epilogues. RunTracer(), Interpret(), and Invoke() all
        // rely on this property.
        JS_ASSERT(!f.fp()->finishedInInterpreter());
        js_UnwindScope(cx, 0, cx->isExceptionPending());
        ScriptEpilogue(f.cx, f.fp(), false);

        // Don't remove the last frame, this is the responsibility of
        // JaegerShot()'s caller. We only guarantee that ScriptEpilogue()
        // has been run.
        if (f.entryfp == f.fp())
            break;

        JS_ASSERT(f.regs.sp == cx->regs->sp);
        InlineReturn(f);
    }

    JS_ASSERT(f.regs.sp == cx->regs->sp);

    if (!pc)
        return NULL;

    JSStackFrame *fp = cx->fp();
    JSScript *script = fp->script();
    return script->nativeCodeForPC(fp->isConstructing(), pc);
}