util.go raw
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", "amd64")
26 GOOS = envOr("GOOS", "linux")
27 GO386 = envOr("GO386", "")
28 GOAMD64 = goamd64()
29 GOARM = goarm()
30 GOMIPS = gomips()
31 GOMIPS64 = gomips64()
32 GOPPC64 = goppc64()
33 GOWASM = gowasm()
34 GO_LDSO = ""
35 Version = ""
36 )
37
38 const (
39 ElfRelocOffset = 256
40 MachoRelocOffset = 2048 // reserve enough space for ELF relocations
41 Go115AMD64 = "alignedjumps" // Should be "alignedjumps" or "normaljumps"; this replaces environment variable introduced in CL 219357.
42 )
43
44 // TODO(1.16): assuming no issues in 1.15 release, remove this and related constant.
45 func goamd64() string {
46 return Go115AMD64
47 }
48
49 func goarm() int {
50 switch v := envOr("GOARM", "7"); v {
51 case "5":
52 return 5
53 case "6":
54 return 6
55 case "7":
56 return 7
57 }
58 // Fail here, rather than validate at multiple call sites.
59 log.Fatalf("Invalid GOARM value. Must be 5, 6, or 7.")
60 panic("unreachable")
61 }
62
63 func gomips() string {
64 switch v := envOr("GOMIPS", "hardfloat"); v {
65 case "hardfloat", "softfloat":
66 return v
67 }
68 log.Fatalf("Invalid GOMIPS value. Must be hardfloat or softfloat.")
69 panic("unreachable")
70 }
71
72 func gomips64() string {
73 switch v := envOr("GOMIPS64", "hardfloat"); v {
74 case "hardfloat", "softfloat":
75 return v
76 }
77 log.Fatalf("Invalid GOMIPS64 value. Must be hardfloat or softfloat.")
78 panic("unreachable")
79 }
80
81 func goppc64() int {
82 switch v := envOr("GOPPC64", "power8"); v {
83 case "power8":
84 return 8
85 case "power9":
86 return 9
87 }
88 log.Fatalf("Invalid GOPPC64 value. Must be power8 or power9.")
89 panic("unreachable")
90 }
91
92 type gowasmFeatures struct {
93 SignExt bool
94 SatConv bool
95 }
96
97 func (f gowasmFeatures) String() string {
98 var flags []string
99 if f.SatConv {
100 flags = append(flags, "satconv")
101 }
102 if f.SignExt {
103 flags = append(flags, "signext")
104 }
105 return strings.Join(flags, ",")
106 }
107
108 func gowasm() (f gowasmFeatures) {
109 for _, opt := range strings.Split(envOr("GOWASM", ""), ",") {
110 switch opt {
111 case "satconv":
112 f.SatConv = true
113 case "signext":
114 f.SignExt = true
115 case "":
116 // ignore
117 default:
118 log.Fatalf("Invalid GOWASM value. No such feature: " + opt)
119 }
120 }
121 return
122 }
123
124 func Getgoextlinkenabled() string {
125 return envOr("GO_EXTLINK_ENABLED", "")
126 }
127
128 func init() {
129 for _, f := range strings.Split("", ",") {
130 if f != "" {
131 addexp(f)
132 }
133 }
134
135 // regabi is only supported on amd64.
136 if GOARCH != "amd64" {
137 Regabi_enabled = 0
138 }
139 }
140
141 // Note: must agree with runtime.framepointer_enabled.
142 var Framepointer_enabled = GOARCH == "amd64" || GOARCH == "arm64" && (GOOS == "linux" || GOOS == "darwin")
143
144 func addexp(s string) {
145 // Could do general integer parsing here, but the runtime copy doesn't yet.
146 v := 1
147 name := s
148 if len(name) > 2 && name[:2] == "no" {
149 v = 0
150 name = name[2:]
151 }
152 for i := 0; i < len(exper); i++ {
153 if exper[i].name == name {
154 if exper[i].val != nil {
155 *exper[i].val = v
156 }
157 return
158 }
159 }
160
161 fmt.Printf("unknown experiment %s\n", s)
162 os.Exit(2)
163 }
164
165 var (
166 Fieldtrack_enabled int
167 Preemptibleloops_enabled int
168 Staticlockranking_enabled int
169 Regabi_enabled int
170 )
171
172 // Toolchain experiments.
173 // These are controlled by the GOEXPERIMENT environment
174 // variable recorded when the toolchain is built.
175 // This list is also known to cmd/gc.
176 var exper = []struct {
177 name string
178 val *int
179 }{
180 {"fieldtrack", &Fieldtrack_enabled},
181 {"preemptibleloops", &Preemptibleloops_enabled},
182 {"staticlockranking", &Staticlockranking_enabled},
183 {"regabi", &Regabi_enabled},
184 }
185
186 var defaultExpstring = Expstring()
187
188 func DefaultExpstring() string {
189 return defaultExpstring
190 }
191
192 func Expstring() string {
193 buf := "X"
194 for i := range exper {
195 if *exper[i].val != 0 {
196 buf += "," + exper[i].name
197 }
198 }
199 if buf == "X" {
200 buf += ",none"
201 }
202 return "X:" + buf[2:]
203 }
204