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Source file src/cmd/internal/objabi/util.go

Documentation: cmd/internal/objabi

     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  	defaultGOROOT string // set by linker
    23  
    24  	GOROOT  = envOr("GOROOT", defaultGOROOT)
    25  	GOARCH  = envOr("GOARCH", defaultGOARCH)
    26  	GOOS    = envOr("GOOS", defaultGOOS)
    27  	GO386   = envOr("GO386", defaultGO386)
    28  	GOARM   = goarm()
    29  	GOMIPS  = gomips()
    30  	Version = version
    31  )
    32  
    33  func goarm() int {
    34  	switch v := envOr("GOARM", defaultGOARM); v {
    35  	case "5":
    36  		return 5
    37  	case "6":
    38  		return 6
    39  	case "7":
    40  		return 7
    41  	}
    42  	// Fail here, rather than validate at multiple call sites.
    43  	log.Fatalf("Invalid GOARM value. Must be 5, 6, or 7.")
    44  	panic("unreachable")
    45  }
    46  
    47  func gomips() string {
    48  	switch v := envOr("GOMIPS", defaultGOMIPS); v {
    49  	case "hardfloat", "softfloat":
    50  		return v
    51  	}
    52  	log.Fatalf("Invalid GOMIPS value. Must be hardfloat or softfloat.")
    53  	panic("unreachable")
    54  }
    55  
    56  func Getgoextlinkenabled() string {
    57  	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
    58  }
    59  
    60  func init() {
    61  	for _, f := range strings.Split(goexperiment, ",") {
    62  		if f != "" {
    63  			addexp(f)
    64  		}
    65  	}
    66  }
    67  
    68  func Framepointer_enabled(goos, goarch string) bool {
    69  	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
    70  }
    71  
    72  func addexp(s string) {
    73  	// Could do general integer parsing here, but the runtime copy doesn't yet.
    74  	v := 1
    75  	name := s
    76  	if len(name) > 2 && name[:2] == "no" {
    77  		v = 0
    78  		name = name[2:]
    79  	}
    80  	for i := 0; i < len(exper); i++ {
    81  		if exper[i].name == name {
    82  			if exper[i].val != nil {
    83  				*exper[i].val = v
    84  			}
    85  			return
    86  		}
    87  	}
    88  
    89  	fmt.Printf("unknown experiment %s\n", s)
    90  	os.Exit(2)
    91  }
    92  
    93  var (
    94  	framepointer_enabled     int = 1
    95  	Fieldtrack_enabled       int
    96  	Preemptibleloops_enabled int
    97  	Clobberdead_enabled      int
    98  )
    99  
   100  // Toolchain experiments.
   101  // These are controlled by the GOEXPERIMENT environment
   102  // variable recorded when the toolchain is built.
   103  // This list is also known to cmd/gc.
   104  var exper = []struct {
   105  	name string
   106  	val  *int
   107  }{
   108  	{"fieldtrack", &Fieldtrack_enabled},
   109  	{"framepointer", &framepointer_enabled},
   110  	{"preemptibleloops", &Preemptibleloops_enabled},
   111  	{"clobberdead", &Clobberdead_enabled},
   112  }
   113  
   114  var defaultExpstring = Expstring()
   115  
   116  func DefaultExpstring() string {
   117  	return defaultExpstring
   118  }
   119  
   120  func Expstring() string {
   121  	buf := "X"
   122  	for i := range exper {
   123  		if *exper[i].val != 0 {
   124  			buf += "," + exper[i].name
   125  		}
   126  	}
   127  	if buf == "X" {
   128  		buf += ",none"
   129  	}
   130  	return "X:" + buf[2:]
   131  }
   132  

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