// Check invariants and reflects math.
	if t.Key.Equal == nil {
		throw("runtime.reflect_makemap: unsupported map key type")
	}
	if t.Key.Size_ > abi.MapMaxKeyBytes && (!t.IndirectKey() || t.KeySize != uint8(goarch.PtrSize)) ||
		t.Key.Size_ <= abi.MapMaxKeyBytes && (t.IndirectKey() || t.KeySize != uint8(t.Key.Size_)) {
		throw("key size wrong")
	}

	mt.Key = ktyp
	mt.Elem = etyp
	mt.Bucket = bucketOf(ktyp, etyp)
	mt.Hasher = func(p unsafe.Pointer, seed uintptr) uintptr {
		return typehash(ktyp, p, seed)
	}
	mt.Flags = 0
	if ktyp.Size_ > abi.MapMaxKeyBytes {
		mt.KeySize = uint8(goarch.PtrSize)
		mt.Flags |= 1 // indirect key
	} else {
		mt.KeySize = uint8(ktyp.Size_)
	}
	if etyp.Size_ > abi.MapMaxElemBytes {
		mt.ValueSize = uint8(goarch.PtrSize)