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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime_test
import (
"bytes"
"runtime"
"testing"
)
// TestGCInfo tests that various objects in heap, data and bss receive correct GC pointer type info.
func TestGCInfo(t *testing.T) {
verifyGCInfo(t, "bss ScalarPtr", &bssScalarPtr, nonStackInfo(infoScalarPtr))
verifyGCInfo(t, "bss PtrScalar", &bssPtrScalar, nonStackInfo(infoPtrScalar))
verifyGCInfo(t, "bss BigStruct", &bssBigStruct, nonStackInfo(infoBigStruct()))
verifyGCInfo(t, "bss string", &bssString, nonStackInfo(infoString))
verifyGCInfo(t, "bss slice", &bssSlice, nonStackInfo(infoSlice))
verifyGCInfo(t, "bss eface", &bssEface, nonStackInfo(infoEface))
verifyGCInfo(t, "bss iface", &bssIface, nonStackInfo(infoIface))
verifyGCInfo(t, "data ScalarPtr", &dataScalarPtr, nonStackInfo(infoScalarPtr))
verifyGCInfo(t, "data PtrScalar", &dataPtrScalar, nonStackInfo(infoPtrScalar))
verifyGCInfo(t, "data BigStruct", &dataBigStruct, nonStackInfo(infoBigStruct()))
verifyGCInfo(t, "data string", &dataString, nonStackInfo(infoString))
verifyGCInfo(t, "data slice", &dataSlice, nonStackInfo(infoSlice))
verifyGCInfo(t, "data eface", &dataEface, nonStackInfo(infoEface))
verifyGCInfo(t, "data iface", &dataIface, nonStackInfo(infoIface))
verifyGCInfo(t, "stack ScalarPtr", new(ScalarPtr), infoScalarPtr)
verifyGCInfo(t, "stack PtrScalar", new(PtrScalar), infoPtrScalar)
verifyGCInfo(t, "stack BigStruct", new(BigStruct), infoBigStruct())
verifyGCInfo(t, "stack string", new(string), infoString)
verifyGCInfo(t, "stack slice", new([]string), infoSlice)
verifyGCInfo(t, "stack eface", new(interface{}), infoEface)
verifyGCInfo(t, "stack iface", new(Iface), infoIface)
for i := 0; i < 10; i++ {
verifyGCInfo(t, "heap ScalarPtr", escape(new(ScalarPtr)), nonStackInfo(infoScalarPtr))
verifyGCInfo(t, "heap PtrScalar", escape(new(PtrScalar)), nonStackInfo(infoPtrScalar))
verifyGCInfo(t, "heap BigStruct", escape(new(BigStruct)), nonStackInfo(infoBigStruct()))
verifyGCInfo(t, "heap string", escape(new(string)), nonStackInfo(infoString))
verifyGCInfo(t, "heap eface", escape(new(interface{})), nonStackInfo(infoEface))
verifyGCInfo(t, "heap iface", escape(new(Iface)), nonStackInfo(infoIface))
}
}
func verifyGCInfo(t *testing.T, name string, p interface{}, mask0 []byte) {
mask := runtime.GCMask(p)
if len(mask) > len(mask0) {
mask0 = append(mask0, BitsDead)
mask = mask[:len(mask0)]
}
if bytes.Compare(mask, mask0) != 0 {
t.Errorf("bad GC program for %v:\nwant %+v\ngot %+v", name, mask0, mask)
return
}
}
func nonStackInfo(mask []byte) []byte {
// BitsDead is replaced with BitsScalar everywhere except stacks.
mask1 := make([]byte, len(mask))
mw := false
for i, v := range mask {
if !mw && v == BitsDead {
v = BitsScalar
}
mw = !mw && v == BitsMultiWord
mask1[i] = v
}
return mask1
}
var gcinfoSink interface{}
func escape(p interface{}) interface{} {
gcinfoSink = p
return p
}
const (
BitsDead = iota
BitsScalar
BitsPointer
BitsMultiWord
)
const (
BitsString = iota // unused
BitsSlice // unused
BitsIface
BitsEface
)
type ScalarPtr struct {
q int
w *int
e int
r *int
t int
y *int
}
var infoScalarPtr = []byte{BitsScalar, BitsPointer, BitsScalar, BitsPointer, BitsScalar, BitsPointer}
type PtrScalar struct {
q *int
w int
e *int
r int
t *int
y int
}
var infoPtrScalar = []byte{BitsPointer, BitsScalar, BitsPointer, BitsScalar, BitsPointer, BitsScalar}
type BigStruct struct {
q *int
w byte
e [17]byte
r []byte
t int
y uint16
u uint64
i string
}
func infoBigStruct() []byte {
switch runtime.GOARCH {
case "386", "arm":
return []byte{
BitsPointer, // q *int
BitsScalar, BitsScalar, BitsScalar, BitsScalar, BitsScalar, // w byte; e [17]byte
BitsPointer, BitsDead, BitsDead, // r []byte
BitsScalar, BitsScalar, BitsScalar, BitsScalar, // t int; y uint16; u uint64
BitsPointer, BitsDead, // i string
}
case "amd64":
return []byte{
BitsPointer, // q *int
BitsScalar, BitsScalar, BitsScalar, // w byte; e [17]byte
BitsPointer, BitsDead, BitsDead, // r []byte
BitsScalar, BitsScalar, BitsScalar, // t int; y uint16; u uint64
BitsPointer, BitsDead, // i string
}
case "amd64p32":
return []byte{
BitsPointer, // q *int
BitsScalar, BitsScalar, BitsScalar, BitsScalar, BitsScalar, // w byte; e [17]byte
BitsPointer, BitsDead, BitsDead, // r []byte
BitsScalar, BitsScalar, BitsDead, BitsScalar, BitsScalar, // t int; y uint16; u uint64
BitsPointer, BitsDead, // i string
}
case "power64", "power64le":
return []byte{
BitsPointer, BitsScalar, BitsScalar, BitsScalar,
BitsMultiWord, BitsSlice, BitsScalar, BitsScalar,
BitsScalar, BitsScalar, BitsMultiWord, BitsString,
}
default:
panic("unknown arch")
}
}
type Iface interface {
f()
}
type IfaceImpl int
func (IfaceImpl) f() {
}
var (
// BSS
bssScalarPtr ScalarPtr
bssPtrScalar PtrScalar
bssBigStruct BigStruct
bssString string
bssSlice []string
bssEface interface{}
bssIface Iface
// DATA
dataScalarPtr = ScalarPtr{q: 1}
dataPtrScalar = PtrScalar{w: 1}
dataBigStruct = BigStruct{w: 1}
dataString = "foo"
dataSlice = []string{"foo"}
dataEface interface{} = 42
dataIface Iface = IfaceImpl(42)
infoString = []byte{BitsPointer, BitsDead}
infoSlice = []byte{BitsPointer, BitsDead, BitsDead}
infoEface = []byte{BitsMultiWord, BitsEface}
infoIface = []byte{BitsMultiWord, BitsIface}
)
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