Пример #1
0
void *
RunTracer(VMFrame &f)
#endif
{
    JSContext *cx = f.cx;
    StackFrame *entryFrame = f.fp();
    TracePointAction tpa;

    /* :TODO: nuke PIC? */
    if (!cx->traceJitEnabled)
        return NULL;

    /*
     * Force initialization of the entry frame's scope chain and return value,
     * if necessary.  The tracer can query the scope chain without needing to
     * check the HAS_SCOPECHAIN flag, and the frame is guaranteed to have the
     * correct return value stored if we trace/interpret through to the end
     * of the frame.
     */
    entryFrame->scopeChain();
    entryFrame->returnValue();

    bool blacklist;
    void **traceData;
    uintN *traceEpoch;
    uint32 *loopCounter;
    uint32 hits;
#if JS_MONOIC
    traceData = &ic.traceData;
    traceEpoch = &ic.traceEpoch;
    loopCounter = &ic.loopCounter;
    *loopCounter = 1;
    hits = ic.loopCounterStart;
#else
    traceData = NULL;
    traceEpoch = NULL;
    loopCounter = NULL;
    hits = 1;
#endif
    tpa = MonitorTracePoint(f.cx, &blacklist, traceData, traceEpoch,
                            loopCounter, hits);
    JS_ASSERT(!TRACE_RECORDER(cx));

#if JS_MONOIC
    ic.loopCounterStart = *loopCounter;
    if (blacklist)
        DisableTraceHint(entryFrame->jit(), ic);
#endif

    // Even though ExecuteTree() bypasses the interpreter, it should propagate
    // error failures correctly.
    JS_ASSERT_IF(cx->isExceptionPending(), tpa == TPA_Error);

    JS_ASSERT(f.fp() == cx->fp());
    switch (tpa) {
      case TPA_Nothing:
        return NULL;

      case TPA_Error:
        if (!HandleErrorInExcessFrame(f, entryFrame, f.fp()->finishedInInterpreter()))
            THROWV(NULL);
        JS_ASSERT(!cx->fp()->hasImacropc());
        break;

      case TPA_RanStuff:
      case TPA_Recorded:
        break;
    }

    /*
     * The tracer could have dropped us off on any frame at any position.
     * Well, it could not have removed frames (recursion is disabled).
     *
     * Frames after the entryFrame cannot be entered via JaegerShotAtSafePoint()
     * unless each is at a safe point. We can JaegerShotAtSafePoint these
     * frames individually, but we must unwind to the entryFrame.
     *
     * Note carefully that JaegerShotAtSafePoint can resume methods at
     * arbitrary safe points whereas JaegerShot cannot.
     *
     * If we land on entryFrame without a safe point in sight, we'll end up
     * at the RETURN op. This is an edge case with two paths:
     *
     * 1) The entryFrame is the last inline frame. If it fell on a RETURN,
     *    move the return value down.
     * 2) The entryFrame is NOT the last inline frame. Pop the frame.
     *
     * In both cases, we hijack the stub to return to the force-return
     * trampoline. This trampoline simulates the frame-popping portion of
     * emitReturn (except without the benefit of the FrameState) and will
     * produce the necessary register state to return to the caller.
     */

  restart:
    /* Step 1. Finish frames created after the entry frame. */
    if (!FinishExcessFrames(f, entryFrame))
        THROWV(NULL);

    /* IMacros are guaranteed to have been removed by now. */
    JS_ASSERT(f.fp() == entryFrame);
    JS_ASSERT(!entryFrame->hasImacropc());

    /* Step 2. If entryFrame is done, use a special path to return to EnterMethodJIT(). */
    if (FrameIsFinished(cx)) {
        if (!HandleFinishedFrame(f, entryFrame))
            THROWV(NULL);
        *f.returnAddressLocation() = cx->jaegerCompartment()->forceReturnFromFastCall();
        return NULL;
    }

    /* Step 3. If entryFrame is at a safe point, just leave. */
    if (void *ncode = AtSafePoint(cx))
        return ncode;

    /* Step 4. Do a partial interp, then restart the whole process. */
    if (!PartialInterpret(f)) {
        if (!HandleErrorInExcessFrame(f, entryFrame))
            THROWV(NULL);
    }

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

    ExpandInlineFrames(cx->compartment);

    // The current frame may have an associated orphaned native, if the native
    // or SplatApplyArgs threw an exception.
    RemoveOrphanedNative(cx, f.fp());

    JS_ASSERT(!f.fp()->finishedInInterpreter());

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

    jsbytecode *pc = NULL;
    for (;;) {
        if (cx->isExceptionPending()) {
            // Call the throw hook if necessary
            JSThrowHook handler = cx->runtime->debugHooks.throwHook;
            if (handler || !cx->compartment->getDebuggees().empty()) {
                Value rval;
                JSTrapStatus st = Debugger::onExceptionUnwind(cx, &rval);
                if (st == JSTRAP_CONTINUE && handler) {
                    st = handler(cx, cx->fp()->script(), cx->regs().pc, &rval,
                                 cx->runtime->debugHooks.throwHookData);
                }

                switch (st) {
                case JSTRAP_ERROR:
                    cx->clearPendingException();
                    break;

                case JSTRAP_CONTINUE:
                    break;

                case JSTRAP_RETURN:
                    cx->clearPendingException();
                    cx->fp()->setReturnValue(rval);
                    return cx->jaegerCompartment()->forceReturnFromExternC();

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

                default:
                    JS_NOT_REACHED("bad onExceptionUnwind status");
                }
            }
        }

        pc = FindExceptionHandler(cx);
        if (pc)
            break;

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

        if (cx->compartment->debugMode()) {
            // This can turn a throw or error into a healthy return. Note that
            // we will run ScriptDebugEpilogue again (from AnyFrameEpilogue);
            // ScriptDebugEpilogue is prepared for this eventuality.
            if (js::ScriptDebugEpilogue(cx, f.fp(), false))
                return cx->jaegerCompartment()->forceReturnFromExternC();
        }
                

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

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

    if (!pc)
        return NULL;

    StackFrame *fp = cx->fp();
    JSScript *script = fp->script();

    /*
     * Fall back to EnterMethodJIT and finish the frame in the interpreter.
     * With type inference enabled, we may wipe out all JIT code on the
     * stack without patching ncode values to jump to the interpreter, and
     * thus can only enter JIT code via EnterMethodJIT (which overwrites
     * its entry frame's ncode). See ClearAllFrames.
     */
    cx->compartment->jaegerCompartment()->setLastUnfinished(Jaeger_Unfinished);

    if (!script->ensureRanAnalysis(cx, NULL)) {
        js_ReportOutOfMemory(cx);
        return NULL;
    }

    analyze::AutoEnterAnalysis enter(cx);

    /*
     * Interpret the ENTERBLOCK and EXCEPTION opcodes, so that we don't go
     * back into the interpreter with a pending exception. This will cause
     * it to immediately rethrow.
     */
    if (cx->isExceptionPending()) {
        JS_ASSERT(JSOp(*pc) == JSOP_ENTERBLOCK);
        StaticBlockObject &blockObj = script->getObject(GET_UINT32_INDEX(pc))->asStaticBlock();
        Value *vp = cx->regs().sp + blockObj.slotCount();
        SetValueRangeToUndefined(cx->regs().sp, vp);
        cx->regs().sp = vp;
        JS_ASSERT(JSOp(pc[JSOP_ENTERBLOCK_LENGTH]) == JSOP_EXCEPTION);
        cx->regs().sp[0] = cx->getPendingException();
        cx->clearPendingException();
        cx->regs().sp++;
        cx->regs().pc = pc + JSOP_ENTERBLOCK_LENGTH + JSOP_EXCEPTION_LENGTH;
        cx->regs().fp()->setBlockChain(&blockObj);
    }

    *f.oldregs = f.regs;

    return NULL;
}
Пример #3
0
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);

    jsbytecode *pc = NULL;
    for (;;) {
        if (cx->isExceptionPending()) {
            // Call the throw hook if necessary
            JSThrowHook handler = cx->debugHooks->throwHook;
            if (handler || !cx->compartment->getDebuggees().empty()) {
                Value rval;
                JSTrapStatus st = Debugger::onExceptionUnwind(cx, &rval);
                if (st == JSTRAP_CONTINUE && handler) {
                    st = handler(cx, cx->fp()->script(), cx->regs().pc, Jsvalify(&rval),
                                 cx->debugHooks->throwHookData);
                }

                switch (st) {
                case JSTRAP_ERROR:
                    cx->clearPendingException();
                    return NULL;

                case JSTRAP_RETURN:
                    cx->clearPendingException();
                    cx->fp()->setReturnValue(rval);
                    return cx->jaegerCompartment()->forceReturnFromExternC();

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

                default:
                    break;
                }
            }
        }

        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;

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