github.com/FenixAra/go@v0.0.0-20170127160404-96ea0918e670/src/cmd/internal/obj/go.go (about)

     1  // Copyright 2009 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 obj
     6  
     7  import (
     8  	"fmt"
     9  	"os"
    10  	"strings"
    11  )
    12  
    13  // go-specific code shared across loaders (5l, 6l, 8l).
    14  
    15  var (
    16  	framepointer_enabled     int
    17  	Fieldtrack_enabled       int
    18  	Preemptibleloops_enabled int
    19  )
    20  
    21  // Toolchain experiments.
    22  // These are controlled by the GOEXPERIMENT environment
    23  // variable recorded when the toolchain is built.
    24  // This list is also known to cmd/gc.
    25  var exper = []struct {
    26  	name string
    27  	val  *int
    28  }{
    29  	{"fieldtrack", &Fieldtrack_enabled},
    30  	{"framepointer", &framepointer_enabled},
    31  	{"preemptibleloops", &Preemptibleloops_enabled},
    32  }
    33  
    34  func addexp(s string) {
    35  	// Could do general integer parsing here, but the runtime copy doesn't yet.
    36  	v := 1
    37  	name := s
    38  	if len(name) > 2 && name[:2] == "no" {
    39  		v = 0
    40  		name = name[2:]
    41  	}
    42  	for i := 0; i < len(exper); i++ {
    43  		if exper[i].name == name {
    44  			if exper[i].val != nil {
    45  				*exper[i].val = v
    46  			}
    47  			return
    48  		}
    49  	}
    50  
    51  	fmt.Printf("unknown experiment %s\n", s)
    52  	os.Exit(2)
    53  }
    54  
    55  func init() {
    56  	framepointer_enabled = 1 // default
    57  	for _, f := range strings.Split(goexperiment, ",") {
    58  		if f != "" {
    59  			addexp(f)
    60  		}
    61  	}
    62  }
    63  
    64  func Framepointer_enabled(goos, goarch string) bool {
    65  	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
    66  }
    67  
    68  func Nopout(p *Prog) {
    69  	p.As = ANOP
    70  	p.Scond = 0
    71  	p.From = Addr{}
    72  	p.From3 = nil
    73  	p.Reg = 0
    74  	p.To = Addr{}
    75  }
    76  
    77  func Expstring() string {
    78  	buf := "X"
    79  	for i := range exper {
    80  		if *exper[i].val != 0 {
    81  			buf += "," + exper[i].name
    82  		}
    83  	}
    84  	if buf == "X" {
    85  		buf += ",none"
    86  	}
    87  	return "X:" + buf[2:]
    88  }