// avoided.
func TestWriterReadFromCounts(t *testing.T) {
	var w0 writeCountingDiscard
	b0 := NewWriterSize(&w0, 1234)
	b0.WriteString(strings.Repeat("x", 1000))
	if w0 != 0 {
		t.Fatalf("write 1000 'x's: got %d writes, want 0", w0)
	}
	b0.WriteString(strings.Repeat("x", 200))
	if w0 != 0 {
		t.Fatalf("write 1200 'x's: got %d writes, want 0", w0)
	}

0000460 18 a6 83 1b e3 9f ad 79 fe fd 1b 8b f1 fc 41 6f
0000470 d4 13 1f e3 b8 83 ba 64 92 e7 eb e4 77 05 8f ba
0000480 fa 3b 00 00 ff ff 50 4b 07 08 a6 18 b1 91 5e 04
0000490 00 00 e4 47 00 00 50 4b 01 02 14 00 14 00 08 00
00004a0 08 00 00 00 00 00 a6 18 b1 91 5e 04 00 00 e4 47
00004b0 00 00 0a 00 00 00 00 00 00 00 00 00 00 00 00 00
00004c0 00 00 00 00 62 69 67 67 65 72 2e 7a 69 70 50 4b

	FSTPS	(F3, F4), 11(RSP)   // fb2f00916313002d
	FSTPS	(F3, F4), 1024(RSP) // fb0310916313002d
	FSTPS	(F3, F4), x(SB)
	FSTPS	(F3, F4), x+8(SB)

// FLDPQ/FSTPQ
	FLDPQ   -4000(R0), (F1, F2)  // 1b803ed1610b40ad
	FLDPQ	-1024(R0), (F1, F2)  // 010860ad
	FLDPQ	(R0), (F1, F2)       // 010840ad
	FLDPQ	16(R0), (F1, F2)     // 018840ad
	FLDPQ	-16(R0), (F1, F2)    // 01887fad

	ADDEX R3, R5, $3, R6            // 7cc32f54
	ADDEX R3, $3, R5, R6            // 7cc32f54
	ADDIS $8, R3                    // 3c630008
	ADD   $524288, R3               // 3c630008
	ADDIS $1000, R3, R4             // 3c8303e8

	ANDCC $1, R3                    // 70630001
	ANDCC $1, R3, R4                // 70640001
	ANDCC $-1, R4                   // 3be0ffff7fe42039

		if got := IndexRune([]byte(tt.in), tt.rune); got != tt.want {
			t.Errorf("IndexRune(%q, %d) = %v; want %v", tt.in, tt.rune, got, tt.want)
		}
	}

	haystack := []byte("test世界")
	allocs := testing.AllocsPerRun(1000, func() {
		if i := IndexRune(haystack, 's'); i != 2 {
			t.Fatalf("'s' at %d; want 2", i)
		}
		if i := IndexRune(haystack, '世'); i != 4 {
			t.Fatalf("'世' at %d; want 4", i)
		}
	})
	if allocs != 0 {