hdr := make([]byte, bucketCount/goarch.PtrSize)

	verifyMapBucket := func(t *testing.T, k, e Type, m any, want []byte) {
		verifyGCBits(t, MapBucketOf(k, e), want)
		verifyGCBits(t, CachedBucketOf(TypeOf(m)), want)
	}
	verifyMapBucket(t,
		Tscalar, Tptr,
		map[Xscalar]Xptr(nil),
		join(hdr, rep(bucketCount, lit(0)), rep(bucketCount, lit(1)), lit(1)))
	verifyMapBucket(t,
		Tscalarptr, Tptr,