} else if a.base.lessThan(b.base) && b.base.lessThan(a.limit) {
		a.limit = b.base
	}
	return a
}

// takeFromFront takes len bytes from the front of the address range, aligning
// the base to align first. On success, returns the aligned start of the region
// taken and true.
func (a *addrRange) takeFromFront(len uintptr, align uint8) (uintptr, bool) {
	base := alignUp(a.base.addr(), uintptr(align)) + len
	if base > a.limit.addr() {

		// Allocate pointer-less objects from the tail end of the chunk.
		v, ok := s.userArenaChunkFree.takeFromBack(size, typ.Align_)
		if ok {
			ptr = unsafe.Pointer(v)
		}
	} else {
		v, ok := s.userArenaChunkFree.takeFromFront(size, typ.Align_)
		if ok {
			ptr = unsafe.Pointer(v)
		}
	}
	if ptr == nil {
		// Failed to allocate.
		mp.mallocing = 0
		releasem(mp)
		return nil
	}
	if s.needzero != 0 {