github.com/activestate/go@v0.0.0-20170614201249-0b81c023a722/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  	framepointer_enabled = 1 // default
    50  	for _, f := range strings.Split(goexperiment, ",") {
    51  		if f != "" {
    52  			addexp(f)
    53  		}
    54  	}
    55  }
    56  
    57  func Framepointer_enabled(goos, goarch string) bool {
    58  	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
    59  }
    60  
    61  func addexp(s string) {
    62  	// Could do general integer parsing here, but the runtime copy doesn't yet.
    63  	v := 1
    64  	name := s
    65  	if len(name) > 2 && name[:2] == "no" {
    66  		v = 0
    67  		name = name[2:]
    68  	}
    69  	for i := 0; i < len(exper); i++ {
    70  		if exper[i].name == name {
    71  			if exper[i].val != nil {
    72  				*exper[i].val = v
    73  			}
    74  			return
    75  		}
    76  	}
    77  
    78  	fmt.Printf("unknown experiment %s\n", s)
    79  	os.Exit(2)
    80  }
    81  
    82  var (
    83  	framepointer_enabled     int
    84  	Fieldtrack_enabled       int
    85  	Preemptibleloops_enabled int
    86  	Clobberdead_enabled      int
    87  )
    88  
    89  // Toolchain experiments.
    90  // These are controlled by the GOEXPERIMENT environment
    91  // variable recorded when the toolchain is built.
    92  // This list is also known to cmd/gc.
    93  var exper = []struct {
    94  	name string
    95  	val  *int
    96  }{
    97  	{"fieldtrack", &Fieldtrack_enabled},
    98  	{"framepointer", &framepointer_enabled},
    99  	{"preemptibleloops", &Preemptibleloops_enabled},
   100  	{"clobberdead", &Clobberdead_enabled},
   101  }
   102  
   103  func Expstring() string {
   104  	buf := "X"
   105  	for i := range exper {
   106  		if *exper[i].val != 0 {
   107  			buf += "," + exper[i].name
   108  		}
   109  	}
   110  	if buf == "X" {
   111  		buf += ",none"
   112  	}
   113  	return "X:" + buf[2:]
   114  }