libgo/go/runtime/gcinfo_test.go

   1 // Copyright 2014 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 // +build ignore
   6
   7 package runtime_test
   8
   9 import (
  10         "bytes"
  11         "runtime"
  12         "testing"
  13 )
  14
  15 const (
  16         typeScalar  = 0
  17         typePointer = 1
  18 )
  19
  20 // TestGCInfo tests that various objects in heap, data and bss receive correct GC pointer type info.
  21 func TestGCInfo(t *testing.T) {
  22         t.Skip("skipping on gccgo for now")
  23
  24         verifyGCInfo(t, "stack Ptr", new(Ptr), infoPtr)
  25         verifyGCInfo(t, "stack ScalarPtr", new(ScalarPtr), infoScalarPtr)
  26         verifyGCInfo(t, "stack PtrScalar", new(PtrScalar), infoPtrScalar)
  27         verifyGCInfo(t, "stack BigStruct", new(BigStruct), infoBigStruct())
  28         verifyGCInfo(t, "stack string", new(string), infoString)
  29         verifyGCInfo(t, "stack slice", new([]string), infoSlice)
  30         verifyGCInfo(t, "stack eface", new(interface{}), infoEface)
  31         verifyGCInfo(t, "stack iface", new(Iface), infoIface)
  32
  33         for i := 0; i < 10; i++ {
  34                 verifyGCInfo(t, "heap Ptr", escape(new(Ptr)), trimDead(padDead(infoPtr)))
  35                 verifyGCInfo(t, "heap PtrSlice", escape(&make([]*byte, 10)[0]), trimDead(infoPtr10))
  36                 verifyGCInfo(t, "heap ScalarPtr", escape(new(ScalarPtr)), trimDead(infoScalarPtr))
  37                 verifyGCInfo(t, "heap ScalarPtrSlice", escape(&make([]ScalarPtr, 4)[0]), trimDead(infoScalarPtr4))
  38                 verifyGCInfo(t, "heap PtrScalar", escape(new(PtrScalar)), trimDead(infoPtrScalar))
  39                 verifyGCInfo(t, "heap BigStruct", escape(new(BigStruct)), trimDead(infoBigStruct()))
  40                 verifyGCInfo(t, "heap string", escape(new(string)), trimDead(infoString))
  41                 verifyGCInfo(t, "heap eface", escape(new(interface{})), trimDead(infoEface))
  42                 verifyGCInfo(t, "heap iface", escape(new(Iface)), trimDead(infoIface))
  43         }
  44 }
  45
  46 func verifyGCInfo(t *testing.T, name string, p interface{}, mask0 []byte) {
  47         mask := runtime.GCMask(p)
  48         if !bytes.Equal(mask, mask0) {
  49                 t.Errorf("bad GC program for %v:\nwant %+v\ngot  %+v", name, mask0, mask)
  50                 return
  51         }
  52 }
  53
  54 func padDead(mask []byte) []byte {
  55         // Because the dead bit isn't encoded in the second word,
  56         // and because on 32-bit systems a one-word allocation
  57         // uses a two-word block, the pointer info for a one-word
  58         // object needs to be expanded to include an extra scalar
  59         // on 32-bit systems to match the heap bitmap.
  60         if runtime.PtrSize == 4 && len(mask) == 1 {
  61                 return []byte{mask[0], 0}
  62         }
  63         return mask
  64 }
  65
  66 func trimDead(mask []byte) []byte {
  67         for len(mask) > 2 && mask[len(mask)-1] == typeScalar {
  68                 mask = mask[:len(mask)-1]
  69         }
  70         if len(mask) == 2 && mask[0] == typeScalar && mask[1] == typeScalar {
  71                 mask = mask[:0]
  72         }
  73         return mask
  74 }
  75
  76 var gcinfoSink interface{}
  77
  78 func escape(p interface{}) interface{} {
  79         gcinfoSink = p
  80         return p
  81 }
  82
  83 var infoPtr = []byte{typePointer}
  84
  85 type Ptr struct {
  86         *byte
  87 }
  88
  89 var infoPtr10 = []byte{typePointer, typePointer, typePointer, typePointer, typePointer, typePointer, typePointer, typePointer, typePointer, typePointer}
  90
  91 type ScalarPtr struct {
  92         q int
  93         w *int
  94         e int
  95         r *int
  96         t int
  97         y *int
  98 }
  99
 100 var infoScalarPtr = []byte{typeScalar, typePointer, typeScalar, typePointer, typeScalar, typePointer}
 101
 102 var infoScalarPtr4 = append(append(append(append([]byte(nil), infoScalarPtr...), infoScalarPtr...), infoScalarPtr...), infoScalarPtr...)
 103
 104 type PtrScalar struct {
 105         q *int
 106         w int
 107         e *int
 108         r int
 109         t *int
 110         y int
 111 }
 112
 113 var infoPtrScalar = []byte{typePointer, typeScalar, typePointer, typeScalar, typePointer, typeScalar}
 114
 115 type BigStruct struct {
 116         q *int
 117         w byte
 118         e [17]byte
 119         r []byte
 120         t int
 121         y uint16
 122         u uint64
 123         i string
 124 }
 125
 126 func infoBigStruct() []byte {
 127         switch runtime.GOARCH {
 128         case "386", "arm":
 129                 return []byte{
 130                         typePointer,                                                // q *int
 131                         typeScalar, typeScalar, typeScalar, typeScalar, typeScalar, // w byte; e [17]byte
 132                         typePointer, typeScalar, typeScalar, // r []byte
 133                         typeScalar, typeScalar, typeScalar, typeScalar, // t int; y uint16; u uint64
 134                         typePointer, typeScalar, // i string
 135                 }
 136         case "arm64", "amd64", "mips64", "mips64le", "ppc64", "ppc64le", "s390x":
 137                 return []byte{
 138                         typePointer,                        // q *int
 139                         typeScalar, typeScalar, typeScalar, // w byte; e [17]byte
 140                         typePointer, typeScalar, typeScalar, // r []byte
 141                         typeScalar, typeScalar, typeScalar, // t int; y uint16; u uint64
 142                         typePointer, typeScalar, // i string
 143                 }
 144         case "amd64p32":
 145                 return []byte{
 146                         typePointer,                                                // q *int
 147                         typeScalar, typeScalar, typeScalar, typeScalar, typeScalar, // w byte; e [17]byte
 148                         typePointer, typeScalar, typeScalar, // r []byte
 149                         typeScalar, typeScalar, typeScalar, typeScalar, typeScalar, // t int; y uint16; u uint64
 150                         typePointer, typeScalar, // i string
 151                 }
 152         default:
 153                 panic("unknown arch")
 154         }
 155 }
 156
 157 type Iface interface {
 158         f()
 159 }
 160
 161 type IfaceImpl int
 162
 163 func (IfaceImpl) f() {
 164 }
 165
 166 var (
 167         // BSS
 168         bssPtr       Ptr
 169         bssScalarPtr ScalarPtr
 170         bssPtrScalar PtrScalar
 171         bssBigStruct BigStruct
 172         bssString    string
 173         bssSlice     []string
 174         bssEface     interface{}
 175         bssIface     Iface
 176
 177         // DATA
 178         dataPtr                   = Ptr{new(byte)}
 179         dataScalarPtr             = ScalarPtr{q: 1}
 180         dataPtrScalar             = PtrScalar{w: 1}
 181         dataBigStruct             = BigStruct{w: 1}
 182         dataString                = "foo"
 183         dataSlice                 = []string{"foo"}
 184         dataEface     interface{} = 42
 185         dataIface     Iface       = IfaceImpl(42)
 186
 187         infoString = []byte{typePointer, typeScalar}
 188         infoSlice  = []byte{typePointer, typeScalar, typeScalar}
 189         infoEface  = []byte{typePointer, typePointer}
 190         infoIface  = []byte{typePointer, typePointer}
 191 )