// whether the span has been zeroed. Note that it may not be.
func (h *mheap) alloc(npages uintptr, spanclass spanClass) *mspan {
	// Don't do any operations that lock the heap on the G stack.
	// It might trigger stack growth, and the stack growth code needs
	// to be able to allocate heap.
	var s *mspan
	systemstack(func() {
		// To prevent excessive heap growth, before allocating n pages

	var stack []*loadPkg
	for p := pkg; p != nil; p = p.stack {
		stack = append(stack, p)
	}

	var buf strings.Builder
	for i := len(stack) - 1; i >= 0; i-- {
		p := stack[i]
		fmt.Fprint(&buf, p.path)
		if p.testOf != nil {
			fmt.Fprint(&buf, ".test")
		}
		if i > 0 {
			if stack[i-1].testOf == p {
				fmt.Fprint(&buf, " tested by\n\t")
			} else {
				fmt.Fprint(&buf, " imports\n\t")

	if flag == "CFLAGS" {
		// We'll also need these when preprocessing for dwarf information.
		// However, discard any -g options: we need to be able
		// to parse the debug info, so stick to what we expect.
		for _, arg := range args {
			if !strings.HasPrefix(arg, "-g") {
				p.GccOptions = append(p.GccOptions, arg)
			}
		}
	}
	if flag == "LDFLAGS" {