github.com/goproxy0/go@v0.0.0-20171111080102-49cc0c489d2c/src/cmd/internal/objabi/util.go (about)

     1  // Copyright 2015 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  package objabi
     6  
     7  import (
     8  	"fmt"
     9  	"log"
    10  	"os"
    11  	"strings"
    12  )
    13  
    14  func envOr(key, value string) string {
    15  	if x := os.Getenv(key); x != "" {
    16  		return x
    17  	}
    18  	return value
    19  }
    20  
    21  var (
    22  	GOROOT  = envOr("GOROOT", defaultGOROOT)
    23  	GOARCH  = envOr("GOARCH", defaultGOARCH)
    24  	GOOS    = envOr("GOOS", defaultGOOS)
    25  	GO386   = envOr("GO386", defaultGO386)
    26  	GOARM   = goarm()
    27  	Version = version
    28  )
    29  
    30  func goarm() int {
    31  	switch v := envOr("GOARM", defaultGOARM); v {
    32  	case "5":
    33  		return 5
    34  	case "6":
    35  		return 6
    36  	case "7":
    37  		return 7
    38  	}
    39  	// Fail here, rather than validate at multiple call sites.
    40  	log.Fatalf("Invalid GOARM value. Must be 5, 6, or 7.")
    41  	panic("unreachable")
    42  }
    43  
    44  func Getgoextlinkenabled() string {
    45  	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
    46  }
    47  
    48  func init() {
    49  	for _, f := range strings.Split(goexperiment, ",") {
    50  		if f != "" {
    51  			addexp(f)
    52  		}
    53  	}
    54  }
    55  
    56  func Framepointer_enabled(goos, goarch string) bool {
    57  	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
    58  }
    59  
    60  func addexp(s string) {
    61  	// Could do general integer parsing here, but the runtime copy doesn't yet.
    62  	v := 1
    63  	name := s
    64  	if len(name) > 2 && name[:2] == "no" {
    65  		v = 0
    66  		name = name[2:]
    67  	}
    68  	for i := 0; i < len(exper); i++ {
    69  		if exper[i].name == name {
    70  			if exper[i].val != nil {
    71  				*exper[i].val = v
    72  			}
    73  			return
    74  		}
    75  	}
    76  
    77  	fmt.Printf("unknown experiment %s\n", s)
    78  	os.Exit(2)
    79  }
    80  
    81  var (
    82  	framepointer_enabled     int = 1
    83  	Fieldtrack_enabled       int
    84  	Preemptibleloops_enabled int
    85  	Clobberdead_enabled      int
    86  )
    87  
    88  // Toolchain experiments.
    89  // These are controlled by the GOEXPERIMENT environment
    90  // variable recorded when the toolchain is built.
    91  // This list is also known to cmd/gc.
    92  var exper = []struct {
    93  	name string
    94  	val  *int
    95  }{
    96  	{"fieldtrack", &Fieldtrack_enabled},
    97  	{"framepointer", &framepointer_enabled},
    98  	{"preemptibleloops", &Preemptibleloops_enabled},
    99  	{"clobberdead", &Clobberdead_enabled},
   100  }
   101  
   102  var defaultExpstring = Expstring()
   103  
   104  func DefaultExpstring() string {
   105  	return defaultExpstring
   106  }
   107  
   108  func Expstring() string {
   109  	buf := "X"
   110  	for i := range exper {
   111  		if *exper[i].val != 0 {
   112  			buf += "," + exper[i].name
   113  		}
   114  	}
   115  	if buf == "X" {
   116  		buf += ",none"
   117  	}
   118  	return "X:" + buf[2:]
   119  }