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
5package objabi
6
7import (
8	"fmt"
9	"log"
10	"os"
11	"strings"
12)
13
14func envOr(key, value string) string {
15	if x := os.Getenv(key); x != "" {
16		return x
17	}
18	return value
19}
20
21var (
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
33func 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
47func 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
56func Getgoextlinkenabled() string {
57	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
58}
59
60func init() {
61	for _, f := range strings.Split(goexperiment, ",") {
62		if f != "" {
63			addexp(f)
64		}
65	}
66}
67
68func Framepointer_enabled(goos, goarch string) bool {
69	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
70}
71
72func 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
93var (
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.
104var 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
114var defaultExpstring = Expstring()
115
116func DefaultExpstring() string {
117	return defaultExpstring
118}
119
120func 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