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

Documentation: cmd/internal/objabi

  // Copyright 2015 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package objabi
  
  import (
  	"fmt"
  	"log"
  	"os"
  	"strings"
  )
  
  func envOr(key, value string) string {
  	if x := os.Getenv(key); x != "" {
  		return x
  	}
  	return value
  }
  
  var (
  	GOROOT  = envOr("GOROOT", defaultGOROOT)
  	GOARCH  = envOr("GOARCH", defaultGOARCH)
  	GOOS    = envOr("GOOS", defaultGOOS)
  	GO386   = envOr("GO386", defaultGO386)
  	GOARM   = goarm()
  	Version = version
  )
  
  func goarm() int {
  	switch v := envOr("GOARM", defaultGOARM); v {
  	case "5":
  		return 5
  	case "6":
  		return 6
  	case "7":
  		return 7
  	}
  	// Fail here, rather than validate at multiple call sites.
  	log.Fatalf("Invalid GOARM value. Must be 5, 6, or 7.")
  	panic("unreachable")
  }
  
  func Getgoextlinkenabled() string {
  	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
  }
  
  func init() {
  	for _, f := range strings.Split(goexperiment, ",") {
  		if f != "" {
  			addexp(f)
  		}
  	}
  }
  
  func Framepointer_enabled(goos, goarch string) bool {
  	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
  }
  
  func addexp(s string) {
  	// Could do general integer parsing here, but the runtime copy doesn't yet.
  	v := 1
  	name := s
  	if len(name) > 2 && name[:2] == "no" {
  		v = 0
  		name = name[2:]
  	}
  	for i := 0; i < len(exper); i++ {
  		if exper[i].name == name {
  			if exper[i].val != nil {
  				*exper[i].val = v
  			}
  			return
  		}
  	}
  
  	fmt.Printf("unknown experiment %s\n", s)
  	os.Exit(2)
  }
  
  var (
  	framepointer_enabled     int = 1
  	Fieldtrack_enabled       int
  	Preemptibleloops_enabled int
  	Clobberdead_enabled      int
  )
  
  // Toolchain experiments.
  // These are controlled by the GOEXPERIMENT environment
  // variable recorded when the toolchain is built.
  // This list is also known to cmd/gc.
  var exper = []struct {
  	name string
  	val  *int
  }{
  	{"fieldtrack", &Fieldtrack_enabled},
  	{"framepointer", &framepointer_enabled},
  	{"preemptibleloops", &Preemptibleloops_enabled},
  	{"clobberdead", &Clobberdead_enabled},
  }
  
  var defaultExpstring = Expstring()
  
  func DefaultExpstring() string {
  	return defaultExpstring
  }
  
  func Expstring() string {
  	buf := "X"
  	for i := range exper {
  		if *exper[i].val != 0 {
  			buf += "," + exper[i].name
  		}
  	}
  	if buf == "X" {
  		buf += ",none"
  	}
  	return "X:" + buf[2:]
  }
  

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