github.com/guyezi/gofrontend@v0.0.0-20200228202240-7a62a49e62c0/libgo/go/internal/bytealg/index_amd64.go (about)

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build ignore_for_gccgo
     6  
     7  package bytealg
     8  
     9  import "internal/cpu"
    10  
    11  const MaxBruteForce = 64
    12  
    13  func init() {
    14  	if cpu.X86.HasAVX2 {
    15  		MaxLen = 63
    16  	} else {
    17  		MaxLen = 31
    18  	}
    19  }
    20  
    21  // Cutover reports the number of failures of IndexByte we should tolerate
    22  // before switching over to Index.
    23  // n is the number of bytes processed so far.
    24  // See the bytes.Index implementation for details.
    25  func Cutover(n int) int {
    26  	// 1 error per 8 characters, plus a few slop to start.
    27  	return (n + 16) / 8
    28  }