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Source file test/fixedbugs/issue4448.go

Documentation: test/fixedbugs

  // run
  
  // Copyright 2012 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Issue 4448: 64-bit indices that are statically known
  // to be bounded make 5g and 8g generate a dangling branch.
  
  package main
  
  const b26 uint64 = 0x022fdd63cc95386d
  
  var bitPos [64]int
  
  func init() {
  	for p := uint(0); p < 64; p++ {
  		bitPos[b26<<p>>58] = int(p)
  	}
  }
  
  func MinPos(w uint64) int {
  	if w == 0 {
  		panic("bit: MinPos(0) undefined")
  	}
  	return bitPos[((w&-w)*b26)>>58]
  }
  
  func main() {
  	const one = uint64(1)
  	for i := 0; i < 64; i++ {
  		if MinPos(1<<uint(i)) != i {
  			println("i =", i)
  			panic("MinPos(1<<uint(i)) != i")
  		}
  	}
  }
  

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