C++ AsmJSModule::usesSignalHandlersForOOB方法代码示例

static bool
ChangeHeap(JSContext *cx, AsmJSModule &module, CallArgs args)
{
    HandleValue bufferArg = args.get(0);
    if (!IsArrayBuffer(bufferArg)) {
        ReportIncompatible(cx, args);
        return false;
    }

    Rooted<ArrayBufferObject*> newBuffer(cx, &bufferArg.toObject().as<ArrayBufferObject>());
    uint32_t heapLength = newBuffer->byteLength();
    if (heapLength & module.heapLengthMask() ||
            heapLength < module.minHeapLength() ||
            heapLength > module.maxHeapLength())
    {
        args.rval().set(BooleanValue(false));
        return true;
    }

    if (!module.hasArrayView()) {
        args.rval().set(BooleanValue(true));
        return true;
    }

    MOZ_ASSERT(IsValidAsmJSHeapLength(heapLength));
    MOZ_ASSERT(!IsDeprecatedAsmJSHeapLength(heapLength));

    if (!ArrayBufferObject::prepareForAsmJS(cx, newBuffer, module.usesSignalHandlersForOOB()))
        return false;

    args.rval().set(BooleanValue(module.changeHeap(newBuffer, cx)));
    return true;
}

static bool
LinkModuleToHeap(JSContext *cx, AsmJSModule &module, Handle<ArrayBufferObject*> heap)
{
    uint32_t heapLength = heap->byteLength();

    if (IsDeprecatedAsmJSHeapLength(heapLength)) {
        LinkFail(cx, "ArrayBuffer byteLengths smaller than 64KB are deprecated and "
                 "will cause a link-time failure in the future");

        // The goal of deprecation is to give apps some time before linking
        // fails. However, if warnings-as-errors is turned on (which happens as
        // part of asm.js testing) an exception may be raised.
        if (cx->isExceptionPending())
            return false;
    }

    if (!IsValidAsmJSHeapLength(heapLength)) {
        ScopedJSFreePtr<char> msg(
            JS_smprintf("ArrayBuffer byteLength 0x%x is not a valid heap length. The next "
                        "valid length is 0x%x",
                        heapLength,
                        RoundUpToNextValidAsmJSHeapLength(heapLength)));
        return LinkFail(cx, msg.get());
    }

    // This check is sufficient without considering the size of the loaded datum because heap
    // loads and stores start on an aligned boundary and the heap byteLength has larger alignment.
    JS_ASSERT((module.minHeapLength() - 1) <= INT32_MAX);
    if (heapLength < module.minHeapLength()) {
        ScopedJSFreePtr<char> msg(
            JS_smprintf("ArrayBuffer byteLength of 0x%x is less than 0x%x (which is the "
                        "largest constant heap access offset rounded up to the next valid "
                        "heap size).",
                        heapLength,
                        module.minHeapLength()));
        return LinkFail(cx, msg.get());
    }

    // If we've generated the code with signal handlers in mind (for bounds
    // checks on x64 and for interrupt callback requesting on all platforms),
    // we need to be able to use signals at runtime. In particular, a module
    // can have been created using signals and cached, and executed without
    // signals activated.
    if (module.usesSignalHandlersForInterrupt() && !cx->canUseSignalHandlers())
        return LinkFail(cx, "Code generated with signal handlers but signals are deactivated");

    if (!ArrayBufferObject::prepareForAsmJS(cx, heap, module.usesSignalHandlersForOOB()))
        return LinkFail(cx, "Unable to prepare ArrayBuffer for asm.js use");

    module.initHeap(heap, cx);
    return true;
}

static bool
LinkModuleToHeap(JSContext* cx, AsmJSModule& module, Handle<ArrayBufferObjectMaybeShared*> heap)
{
    uint32_t heapLength = heap->byteLength();

    if (!IsValidAsmJSHeapLength(heapLength)) {
        ScopedJSFreePtr<char> msg(
            JS_smprintf("ArrayBuffer byteLength 0x%x is not a valid heap length. The next "
                        "valid length is 0x%x",
                        heapLength,
                        RoundUpToNextValidAsmJSHeapLength(heapLength)));
        return LinkFail(cx, msg.get());
    }

    // This check is sufficient without considering the size of the loaded datum because heap
    // loads and stores start on an aligned boundary and the heap byteLength has larger alignment.
    MOZ_ASSERT((module.minHeapLength() - 1) <= INT32_MAX);
    if (heapLength < module.minHeapLength()) {
        ScopedJSFreePtr<char> msg(
            JS_smprintf("ArrayBuffer byteLength of 0x%x is less than 0x%x (the size implied "
                        "by const heap accesses and/or change-heap minimum-length requirements).",
                        heapLength,
                        module.minHeapLength()));
        return LinkFail(cx, msg.get());
    }

    if (heapLength > module.maxHeapLength()) {
        ScopedJSFreePtr<char> msg(
            JS_smprintf("ArrayBuffer byteLength 0x%x is greater than maximum length of 0x%x",
                        heapLength,
                        module.maxHeapLength()));
        return LinkFail(cx, msg.get());
    }

    // If we've generated the code with signal handlers in mind (for bounds
    // checks on x64 and for interrupt callback requesting on all platforms),
    // we need to be able to use signals at runtime. In particular, a module
    // can have been created using signals and cached, and executed without
    // signals activated.
    if (module.usesSignalHandlersForInterrupt() && !cx->canUseSignalHandlers())
        return LinkFail(cx, "Code generated with signal handlers but signals are deactivated");

    if (heap->is<ArrayBufferObject>()) {
        Rooted<ArrayBufferObject*> abheap(cx, &heap->as<ArrayBufferObject>());
        if (!ArrayBufferObject::prepareForAsmJS(cx, abheap, module.usesSignalHandlersForOOB()))
            return LinkFail(cx, "Unable to prepare ArrayBuffer for asm.js use");
    }

    module.initHeap(heap, cx);
    return true;
}