static void
UpdateTraceHintSingle(Repatcher &repatcher, JSC::CodeLocationJump jump, JSC::CodeLocationLabel target)
{
    /*
     * Hack: The value that will be patched is before the executable address,
     * so to get protection right, just unprotect the general region around
     * the jump.
     */
    repatcher.relink(jump, target);

    JaegerSpew(JSpew_PICs, "relinking trace hint %p to %p\n",
               jump.executableAddress(), target.executableAddress());
}
Пример #2
0
static LookupStatus
AttachSetGlobalNameStub(VMFrame &f, ic::SetGlobalNameIC *ic, JSObject *obj, const Shape *shape)
{
    Assembler masm;

    Label start = masm.label();

    DataLabel32 shapeLabel;
    Jump guard = masm.branch32WithPatch(Assembler::NotEqual, ic->shapeReg, Imm32(obj->shape()),
                                        shapeLabel);

    /* A constant object needs rematerialization. */
    if (ic->objConst)
        masm.move(ImmPtr(obj), ic->objReg);

    JS_ASSERT(obj->branded());

    /*
     * Load obj->slots. If ic->objConst, then this clobbers objReg, because
     * ic->objReg == ic->shapeReg.
     */
    JS_ASSERT(!obj->isFixedSlot(shape->slot));
    masm.loadPtr(Address(ic->objReg, JSObject::offsetOfSlots()), ic->shapeReg);

    /* Test if overwriting a function-tagged slot. */
    Address slot(ic->shapeReg, sizeof(Value) * obj->dynamicSlotIndex(shape->slot));
    Jump isNotObject = masm.testObject(Assembler::NotEqual, slot);

    /* Now, test if the object is a function object. */
    masm.loadPayload(slot, ic->shapeReg);
    Jump isFun = masm.testFunction(Assembler::Equal, ic->shapeReg);

    /* Restore shapeReg to obj->slots, since we clobbered it. */
    if (ic->objConst)
        masm.move(ImmPtr(obj), ic->objReg);
    masm.loadPtr(Address(ic->objReg, JSObject::offsetOfSlots()), ic->shapeReg);

    /* If the object test fails, shapeReg is still obj->slots. */
    isNotObject.linkTo(masm.label(), &masm);
    DataLabel32 store = masm.storeValueWithAddressOffsetPatch(ic->vr, slot);

    Jump done = masm.jump();

    JITScript *jit = f.jit();
    LinkerHelper linker(masm, JSC::METHOD_CODE);
    JSC::ExecutablePool *ep = linker.init(f.cx);
    if (!ep)
        return Lookup_Error;
    if (!jit->execPools.append(ep)) {
        ep->release();
        js_ReportOutOfMemory(f.cx);
        return Lookup_Error;
    }

    if (!linker.verifyRange(jit))
        return Lookup_Uncacheable;

    linker.link(done, ic->fastPathStart.labelAtOffset(ic->fastRejoinOffset));
    linker.link(guard, ic->slowPathStart);
    linker.link(isFun, ic->slowPathStart);

    JSC::CodeLocationLabel cs = linker.finalize(f);
    JaegerSpew(JSpew_PICs, "generated setgname stub at %p\n", cs.executableAddress());

    Repatcher repatcher(f.jit());
    repatcher.relink(ic->fastPathStart.jumpAtOffset(ic->inlineShapeJump), cs);

    int offset = linker.locationOf(shapeLabel) - linker.locationOf(start);
    ic->extraShapeGuard = offset;
    JS_ASSERT(ic->extraShapeGuard == offset);

    ic->extraStub = JSC::JITCode(cs.executableAddress(), linker.size());
    offset = linker.locationOf(store) - linker.locationOf(start);
    ic->extraStoreOffset = offset;
    JS_ASSERT(ic->extraStoreOffset == offset);

    ic->hasExtraStub = true;

    return Lookup_Cacheable;
}