case ARNG_B:
			c.checkindex(p, index1, 15)
			c.checkindex(p, index2, 15)
			imm5 |= 1
			imm5 |= index1 << 1
			imm4 |= index2
		case ARNG_H:
			c.checkindex(p, index1, 7)
			c.checkindex(p, index2, 7)
			imm5 |= 2
			imm5 |= index1 << 2
			imm4 |= index2 << 1
		case ARNG_S:
			c.checkindex(p, index1, 3)
			c.checkindex(p, index2, 3)
			imm5 |= 4

	// Using a function literal like this lets us evaluate the
	// function arguments only once while doing pointer checks.
	// This is particularly useful when passing additional arguments
	// to _cgoCheckPointer, as done in checkIndex and checkAddr.
	//
	// When the function argument is a conversion to unsafe.Pointer,
	// we unwrap the conversion before checking the pointer,
	// and then wrap again when calling C.f. This lets us check

}

func (s *ScavengeIndex) Find(force bool) (ChunkIdx, uint) {
	ci, off := s.i.find(force)
	return ChunkIdx(ci), off
}

func (s *ScavengeIndex) AllocRange(base, limit uintptr) {
	sc, ec := chunkIndex(base), chunkIndex(limit-1)
	si, ei := chunkPageIndex(base), chunkPageIndex(limit-1)

	if sc == ec {
		// The range doesn't cross any chunk boundaries.
		s.i.alloc(sc, ei+1-si)
	} else {

	// Update minHeapIdx. Note that even if there's no mapping work to do,
	// we may still have a new, lower minimum heap address.
	minHeapIdx := s.minHeapIdx.Load()
	if baseIdx := uintptr(chunkIndex(base)); minHeapIdx == 0 || baseIdx < minHeapIdx {
		s.minHeapIdx.Store(baseIdx)
	}
	return s.sysGrow(base, limit, sysStat)
}