1// run
2
3// Copyright 2012 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7// Issue 4448: 64-bit indices that are statically known
8// to be bounded make 5g and 8g generate a dangling branch.
9
10package main
11
12const b26 uint64 = 0x022fdd63cc95386d
13
14var bitPos [64]int
15
16func init() {
17	for p := uint(0); p < 64; p++ {
18		bitPos[b26<<p>>58] = int(p)
19	}
20}
21
22func MinPos(w uint64) int {
23	if w == 0 {
24		panic("bit: MinPos(0) undefined")
25	}
26	return bitPos[((w&-w)*b26)>>58]
27}
28
29func main() {
30	const one = uint64(1)
31	for i := 0; i < 64; i++ {
32		if MinPos(1<<uint(i)) != i {
33			println("i =", i)
34			panic("MinPos(1<<uint(i)) != i")
35		}
36	}
37}
38