util.go

Documentation: github.com/twitchyliquid64/golang-asm/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", "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
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