github.com/guyezi/gofrontend@v0.0.0-20200228202240-7a62a49e62c0/libgo/go/internal/bytealg/index_s390x.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_gcco
     6  
     7  package bytealg
     8  
     9  import "internal/cpu"
    10  
    11  const MaxBruteForce = 64
    12  
    13  func init() {
    14  	// Note: we're kind of lucky that this flag is available at this point.
    15  	// The runtime sets HasVX when processing auxv records, and that happens
    16  	// to happen *before* running the init functions of packages that
    17  	// the runtime depends on.
    18  	// TODO: it would really be nicer for internal/cpu to figure out this
    19  	// flag by itself. Then we wouldn't need to depend on quirks of
    20  	// early startup initialization order.
    21  	if cpu.S390X.HasVX {
    22  		MaxLen = 64
    23  	}
    24  }
    25  
    26  // Cutover reports the number of failures of IndexByte we should tolerate
    27  // before switching over to Index.
    28  // n is the number of bytes processed so far.
    29  // See the bytes.Index implementation for details.
    30  func Cutover(n int) int {
    31  	// 1 error per 8 characters, plus a few slop to start.
    32  	return (n + 16) / 8
    33  }