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cmd/compile: split exported/non-exported methods for interface type

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Currently, mhdr/methods is emitted with the same len/cap. There's no way
to distinguish between exported and non-exported methods statically.

This CL splits mhdr/methods into two parts, use "len" for number of
exported methods, and "cap" for all methods. This fixes the bug in
issue #22075, which intends to return the number of exported methods but
currently return all methods.

Note that with this encoding, we still can access either
all/exported-only/non-exported-only methods:

	mhdr[:cap(mhdr)]          // all methods
	mhdr                      // exported methods
	mhdr[len(mhdr):cap(mhdr)] // non-exported methods

Thank to Matthew Dempsky (@mdempsky) for suggesting this encoding.

Fixes #22075

Change-Id: If662adb03ccff27407d55a5578a0ed05a15e7cdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/259237
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Cuong Manh Le 2020-10-03 01:23:47 +07:00 committed by Cuong Manh Le
parent f8df205e74
commit 8f26b57f9a
11 changed files with 124 additions and 64 deletions
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8
doc/go1.16.html
View File

@ -213,6 +213,14 @@ Do not send CLs removing the interior tags from such phrases.
with <code>"use of closed network connection"</code>.
</p>
<h3 id="reflect"><a href="/pkg/reflect/">reflect</a></h3>
<p><!-- CL 259237, golang.org/issue/22075 -->
For interface types and values, <a href="/pkg/reflect/#Value.Method">Method</a>,
<a href="/pkg/reflect/#Value.MethodByName">MethodByName</a>, and
<a href="/pkg/reflect/#Value.NumMethod">NumMethod</a> now
operate on the interface's exported method set, rather than its full method set.
</p>
<h3 id="text/template/parse"><a href="/pkg/text/template/parse/">text/template/parse</a></h3>

3
src/cmd/compile/internal/gc/reflect.go
View File

@ -1275,8 +1275,9 @@ func dtypesym(t *types.Type) *obj.LSym {
}
ot = dgopkgpath(lsym, ot, tpkg)
xcount := sort.Search(n, func(i int) bool { return !types.IsExported(m[i].name.Name) })
ot = dsymptr(lsym, ot, lsym, ot+3*Widthptr+uncommonSize(t))
ot = duintptr(lsym, ot, uint64(n))
ot = duintptr(lsym, ot, uint64(xcount))
ot = duintptr(lsym, ot, uint64(n))
dataAdd := imethodSize() * n
ot = dextratype(lsym, ot, t, dataAdd)

35
src/internal/reflectlite/type.go
View File

@ -234,10 +234,13 @@ type imethod struct {
// interfaceType represents an interface type.
type interfaceType struct {
rtype
pkgPath name // import path
methods []imethod // sorted by hash
pkgPath name // import path
expMethods []imethod // sorted by name, see runtime/type.go:interfacetype to see how it is encoded.
}
func (t *interfaceType) methods() []imethod { return t.expMethods[:cap(t.expMethods)] }
func (t *interfaceType) isEmpty() bool { return cap(t.expMethods) == 0 }
// mapType represents a map type.
type mapType struct {
rtype
@ -695,7 +698,7 @@ func add(p unsafe.Pointer, x uintptr, whySafe string) unsafe.Pointer {
}
// NumMethod returns the number of interface methods in the type's method set.
func (t *interfaceType) NumMethod() int { return len(t.methods) }
func (t *interfaceType) NumMethod() int { return len(t.expMethods) }
// TypeOf returns the reflection Type that represents the dynamic type of i.
// If i is a nil interface value, TypeOf returns nil.
@ -732,9 +735,10 @@ func implements(T, V *rtype) bool {
return false
}
t := (*interfaceType)(unsafe.Pointer(T))
if len(t.methods) == 0 {
if t.isEmpty() {
return true
}
tmethods := t.methods()
// The same algorithm applies in both cases, but the
// method tables for an interface type and a concrete type
@ -751,10 +755,11 @@ func implements(T, V *rtype) bool {
if V.Kind() == Interface {
v := (*interfaceType)(unsafe.Pointer(V))
i := 0
for j := 0; j < len(v.methods); j++ {
tm := &t.methods[i]
vmethods := v.methods()
for j := 0; j < len(vmethods); j++ {
tm := &tmethods[i]
tmName := t.nameOff(tm.name)
vm := &v.methods[j]
vm := &vmethods[j]
vmName := V.nameOff(vm.name)
if vmName.name() == tmName.name() && V.typeOff(vm.typ) == t.typeOff(tm.typ) {
if !tmName.isExported() {
@ -770,7 +775,7 @@ func implements(T, V *rtype) bool {
continue
}
}
if i++; i >= len(t.methods) {
if i++; i >= len(tmethods) {
return true
}
}
@ -785,7 +790,7 @@ func implements(T, V *rtype) bool {
i := 0
vmethods := v.methods()
for j := 0; j < int(v.mcount); j++ {
tm := &t.methods[i]
tm := &tmethods[i]
tmName := t.nameOff(tm.name)
vm := vmethods[j]
vmName := V.nameOff(vm.name)
@ -803,7 +808,7 @@ func implements(T, V *rtype) bool {
continue
}
}
if i++; i >= len(t.methods) {
if i++; i >= len(tmethods) {
return true
}
}
@ -897,7 +902,7 @@ func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
case Interface:
t := (*interfaceType)(unsafe.Pointer(T))
v := (*interfaceType)(unsafe.Pointer(V))
if len(t.methods) == 0 && len(v.methods) == 0 {
if t.isEmpty() && v.isEmpty() {
return true
}
// Might have the same methods but still
@ -962,3 +967,11 @@ func toType(t *rtype) Type {
func ifaceIndir(t *rtype) bool {
return t.kind&kindDirectIface == 0
}
func isEmptyIface(t *rtype) bool {
if t.Kind() != Interface {
return false
}
tt := (*interfaceType)(unsafe.Pointer(t))
return tt.isEmpty()
}

4
src/internal/reflectlite/value.go
View File

@ -228,7 +228,7 @@ func (v Value) Elem() Value {
switch k {
case Interface:
var eface interface{}
if v.typ.NumMethod() == 0 {
if isEmptyIface(v.typ) {
eface = *(*interface{})(v.ptr)
} else {
eface = (interface{})(*(*interface {
@ -433,7 +433,7 @@ func (v Value) assignTo(context string, dst *rtype, target unsafe.Pointer) Value
return Value{dst, nil, flag(Interface)}
}
x := valueInterface(v)
if dst.NumMethod() == 0 {
if isEmptyIface(dst) {
*(*interface{})(target) = x
} else {
ifaceE2I(dst, x, target)

18
src/reflect/all_test.go
View File

@ -2995,6 +2995,14 @@ func TestUnexportedMethods(t *testing.T) {
if got := typ.NumMethod(); got != 0 {
t.Errorf("NumMethod=%d, want 0 satisfied methods", got)
}
var i unexpI
if got := TypeOf(&i).Elem().NumMethod(); got != 0 {
t.Errorf("NumMethod=%d, want 0 satisfied methods", got)
}
if got := ValueOf(&i).Elem().NumMethod(); got != 0 {
t.Errorf("NumMethod=%d, want 0 satisfied methods", got)
}
}
type InnerInt struct {
@ -3648,21 +3656,21 @@ func TestCallPanic(t *testing.T) {
v := ValueOf(T{i, i, i, i, T2{i, i}, i, i, T2{i, i}})
badCall(func() { call(v.Field(0).Method(0)) }) // .t0.W
badCall(func() { call(v.Field(0).Elem().Method(0)) }) // .t0.W
badCall(func() { call(v.Field(0).Method(1)) }) // .t0.w
badMethod(func() { call(v.Field(0).Method(1)) }) // .t0.w
badMethod(func() { call(v.Field(0).Elem().Method(2)) }) // .t0.w
ok(func() { call(v.Field(1).Method(0)) }) // .T1.Y
ok(func() { call(v.Field(1).Elem().Method(0)) }) // .T1.Y
badCall(func() { call(v.Field(1).Method(1)) }) // .T1.y
badMethod(func() { call(v.Field(1).Method(1)) }) // .T1.y
badMethod(func() { call(v.Field(1).Elem().Method(2)) }) // .T1.y
ok(func() { call(v.Field(2).Method(0)) }) // .NamedT0.W
ok(func() { call(v.Field(2).Elem().Method(0)) }) // .NamedT0.W
badCall(func() { call(v.Field(2).Method(1)) }) // .NamedT0.w
badMethod(func() { call(v.Field(2).Method(1)) }) // .NamedT0.w
badMethod(func() { call(v.Field(2).Elem().Method(2)) }) // .NamedT0.w
ok(func() { call(v.Field(3).Method(0)) }) // .NamedT1.Y
ok(func() { call(v.Field(3).Elem().Method(0)) }) // .NamedT1.Y
badCall(func() { call(v.Field(3).Method(1)) }) // .NamedT1.y
badMethod(func() { call(v.Field(3).Method(1)) }) // .NamedT1.y
badMethod(func() { call(v.Field(3).Elem().Method(3)) }) // .NamedT1.y
ok(func() { call(v.Field(4).Field(0).Method(0)) }) // .NamedT2.T1.Y
@ -3672,7 +3680,7 @@ func TestCallPanic(t *testing.T) {
badCall(func() { call(v.Field(5).Method(0)) }) // .namedT0.W
badCall(func() { call(v.Field(5).Elem().Method(0)) }) // .namedT0.W
badCall(func() { call(v.Field(5).Method(1)) }) // .namedT0.w
badMethod(func() { call(v.Field(5).Method(1)) }) // .namedT0.w
badMethod(func() { call(v.Field(5).Elem().Method(2)) }) // .namedT0.w
badCall(func() { call(v.Field(6).Method(0)) }) // .namedT1.Y

55
src/reflect/type.go
View File

@ -386,10 +386,14 @@ type imethod struct {
// interfaceType represents an interface type.
type interfaceType struct {
rtype
pkgPath name // import path
methods []imethod // sorted by hash
pkgPath name // import path
expMethods []imethod // sorted by name, see runtime/type.go:interfacetype to see how it is encoded.
}
// methods returns t's full method set, both exported and non-exported.
func (t *interfaceType) methods() []imethod { return t.expMethods[:cap(t.expMethods)] }
func (t *interfaceType) isEmpty() bool { return cap(t.expMethods) == 0 }
// mapType represents a map type.
type mapType struct {
rtype
@ -1049,25 +1053,22 @@ func (d ChanDir) String() string {
// Method returns the i'th method in the type's method set.
func (t *interfaceType) Method(i int) (m Method) {
if i < 0 || i >= len(t.methods) {
return
if i < 0 || i >= len(t.expMethods) {
panic("reflect: Method index out of range")
}
p := &t.methods[i]
p := &t.expMethods[i]
pname := t.nameOff(p.name)
m.Name = pname.name()
if !pname.isExported() {
m.PkgPath = pname.pkgPath()
if m.PkgPath == "" {
m.PkgPath = t.pkgPath.name()
}
panic("reflect: unexported method: " + pname.name())
}
m.Type = toType(t.typeOff(p.typ))
m.Index = i
return
}
// NumMethod returns the number of interface methods in the type's method set.
func (t *interfaceType) NumMethod() int { return len(t.methods) }
// NumMethod returns the number of exported interface methods in the type's method set.
func (t *interfaceType) NumMethod() int { return len(t.expMethods) }
// MethodByName method with the given name in the type's method set.
func (t *interfaceType) MethodByName(name string) (m Method, ok bool) {
@ -1075,8 +1076,8 @@ func (t *interfaceType) MethodByName(name string) (m Method, ok bool) {
return
}
var p *imethod
for i := range t.methods {
p = &t.methods[i]
for i := range t.expMethods {
p = &t.expMethods[i]
if t.nameOff(p.name).name() == name {
return t.Method(i), true
}
@ -1485,9 +1486,10 @@ func implements(T, V *rtype) bool {
return false
}
t := (*interfaceType)(unsafe.Pointer(T))
if len(t.methods) == 0 {
if t.isEmpty() {
return true
}
tmethods := t.methods()
// The same algorithm applies in both cases, but the
// method tables for an interface type and a concrete type
@ -1504,10 +1506,11 @@ func implements(T, V *rtype) bool {
if V.Kind() == Interface {
v := (*interfaceType)(unsafe.Pointer(V))
i := 0
for j := 0; j < len(v.methods); j++ {
tm := &t.methods[i]
vmethods := v.methods()
for j := 0; j < len(vmethods); j++ {
tm := &tmethods[i]
tmName := t.nameOff(tm.name)
vm := &v.methods[j]
vm := &vmethods[j]
vmName := V.nameOff(vm.name)
if vmName.name() == tmName.name() && V.typeOff(vm.typ) == t.typeOff(tm.typ) {
if !tmName.isExported() {
@ -1523,7 +1526,7 @@ func implements(T, V *rtype) bool {
continue
}
}
if i++; i >= len(t.methods) {
if i++; i >= len(tmethods) {
return true
}
}
@ -1538,7 +1541,7 @@ func implements(T, V *rtype) bool {
i := 0
vmethods := v.methods()
for j := 0; j < int(v.mcount); j++ {
tm := &t.methods[i]
tm := &tmethods[i]
tmName := t.nameOff(tm.name)
vm := vmethods[j]
vmName := V.nameOff(vm.name)
@ -1556,7 +1559,7 @@ func implements(T, V *rtype) bool {
continue
}
}
if i++; i >= len(t.methods) {
if i++; i >= len(tmethods) {
return true
}
}
@ -1658,7 +1661,7 @@ func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
case Interface:
t := (*interfaceType)(unsafe.Pointer(T))
v := (*interfaceType)(unsafe.Pointer(V))
if len(t.methods) == 0 && len(v.methods) == 0 {
if t.isEmpty() && v.isEmpty() {
return true
}
// Might have the same methods but still
@ -2442,7 +2445,7 @@ func StructOf(fields []StructField) Type {
switch f.typ.Kind() {
case Interface:
ift := (*interfaceType)(unsafe.Pointer(ft))
for im, m := range ift.methods {
for im, m := range ift.methods() {
if ift.nameOff(m.name).pkgPath() != "" {
// TODO(sbinet). Issue 15924.
panic("reflect: embedded interface with unexported method(s) not implemented")
@ -3149,3 +3152,11 @@ func addTypeBits(bv *bitVector, offset uintptr, t *rtype) {
}
}
}
func isEmptyIface(rt *rtype) bool {
if rt.Kind() != Interface {
return false
}
tt := (*interfaceType)(unsafe.Pointer(rt))
return len(tt.methods()) == 0
}

21
src/reflect/value.go
View File

@ -635,10 +635,11 @@ func methodReceiver(op string, v Value, methodIndex int) (rcvrtype *rtype, t *fu
i := methodIndex
if v.typ.Kind() == Interface {
tt := (*interfaceType)(unsafe.Pointer(v.typ))
if uint(i) >= uint(len(tt.methods)) {
ttmethods := tt.methods()
if uint(i) >= uint(len(ttmethods)) {
panic("reflect: internal error: invalid method index")
}
m := &tt.methods[i]
m := &ttmethods[i]
if !tt.nameOff(m.name).isExported() {
panic("reflect: " + op + " of unexported method")
}
@ -812,7 +813,7 @@ func (v Value) Elem() Value {
switch k {
case Interface:
var eface interface{}
if v.typ.NumMethod() == 0 {
if isEmptyIface(v.typ) {
eface = *(*interface{})(v.ptr)
} else {
eface = (interface{})(*(*interface {
@ -1033,7 +1034,7 @@ func valueInterface(v Value, safe bool) interface{} {
// Special case: return the element inside the interface.
// Empty interface has one layout, all interfaces with
// methods have a second layout.
if v.NumMethod() == 0 {
if isEmptyIface(v.typ) {
return *(*interface{})(v.ptr)
}
return *(*interface {
@ -1908,10 +1909,11 @@ func (v Value) Type() Type {
if v.typ.Kind() == Interface {
// Method on interface.
tt := (*interfaceType)(unsafe.Pointer(v.typ))
if uint(i) >= uint(len(tt.methods)) {
ttmethods := tt.methods()
if uint(i) >= uint(len(ttmethods)) {
panic("reflect: internal error: invalid method index")
}
m := &tt.methods[i]
m := &ttmethods[i]
return v.typ.typeOff(m.typ)
}
// Method on concrete type.
@ -2429,7 +2431,7 @@ func (v Value) assignTo(context string, dst *rtype, target unsafe.Pointer) Value
return Value{dst, nil, flag(Interface)}
}
x := valueInterface(v, false)
if dst.NumMethod() == 0 {
if isEmptyIface(dst) {
*(*interface{})(target) = x
} else {
ifaceE2I(dst, x, target)
@ -2718,10 +2720,11 @@ func cvtDirect(v Value, typ Type) Value {
func cvtT2I(v Value, typ Type) Value {
target := unsafe_New(typ.common())
x := valueInterface(v, false)
if typ.NumMethod() == 0 {
rt := typ.(*rtype)
if isEmptyIface(rt) {
*(*interface{})(target) = x
} else {
ifaceE2I(typ.(*rtype), x, target)
ifaceE2I(rt, x, target)
}
return Value{typ.common(), target, v.flag.ro() | flagIndir | flag(Interface)}
}

2
src/runtime/alg.go
View File

@ -185,7 +185,7 @@ func typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
return strhash(p, h)
case kindInterface:
i := (*interfacetype)(unsafe.Pointer(t))
if len(i.mhdr) == 0 {
if i.isEmpty() {
return nilinterhash(p, h)
}
return interhash(p, h)

12
src/runtime/iface.go
View File

@ -31,16 +31,17 @@ func itabHashFunc(inter *interfacetype, typ *_type) uintptr {
}
func getitab(inter *interfacetype, typ *_type, canfail bool) *itab {
if len(inter.mhdr) == 0 {
if inter.isEmpty() {
throw("internal error - misuse of itab")
}
imethods := inter.methods()
// easy case
if typ.tflag&tflagUncommon == 0 {
if canfail {
return nil
}
name := inter.typ.nameOff(inter.mhdr[0].name)
name := inter.typ.nameOff(imethods[0].name)
panic(&TypeAssertionError{nil, typ, &inter.typ, name.name()})
}
@ -63,7 +64,7 @@ func getitab(inter *interfacetype, typ *_type, canfail bool) *itab {
}
// Entry doesn't exist yet. Make a new entry & add it.
m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(inter.mhdr)-1)*sys.PtrSize, 0, &memstats.other_sys))
m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(imethods)-1)*sys.PtrSize, 0, &memstats.other_sys))
m.inter = inter
m._type = typ
// The hash is used in type switches. However, compiler statically generates itab's
@ -197,7 +198,8 @@ func (m *itab) init() string {
// and interface names are unique,
// so can iterate over both in lock step;
// the loop is O(ni+nt) not O(ni*nt).
ni := len(inter.mhdr)
imethods := inter.methods()
ni := len(imethods)
nt := int(x.mcount)
xmhdr := (*[1 << 16]method)(add(unsafe.Pointer(x), uintptr(x.moff)))[:nt:nt]
j := 0
@ -205,7 +207,7 @@ func (m *itab) init() string {
var fun0 unsafe.Pointer
imethods:
for k := 0; k < ni; k++ {
i := &inter.mhdr[k]
i := &imethods[k]
itype := inter.typ.typeOff(i.ityp)
name := inter.typ.nameOff(i.name)
iname := name.name()

4
src/runtime/mfinal.go
View File

@ -210,7 +210,7 @@ func runfinq() {
// set up with empty interface
(*eface)(frame)._type = &f.ot.typ
(*eface)(frame).data = f.arg
if len(ityp.mhdr) != 0 {
if !ityp.isEmpty() {
// convert to interface with methods
// this conversion is guaranteed to succeed - we checked in SetFinalizer
*(*iface)(frame) = assertE2I(ityp, *(*eface)(frame))
@ -394,7 +394,7 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
}
case fint.kind&kindMask == kindInterface:
ityp := (*interfacetype)(unsafe.Pointer(fint))
if len(ityp.mhdr) == 0 {
if ityp.isEmpty() {
// ok - satisfies empty interface
goto okarg
}

26
src/runtime/type.go
View File

@ -366,7 +366,19 @@ type imethod struct {
type interfacetype struct {
typ _type
pkgpath name
mhdr []imethod
// expMethods contains all interface methods.
//
// - len(expMethods) returns number of exported methods.
// - cap(expMethods) returns all interface methods, including both exported/non-exported methods.
expMethods []imethod
}
func (it *interfacetype) methods() []imethod {
return it.expMethods[:cap(it.expMethods)]
}
func (it *interfacetype) isEmpty() bool {
return cap(it.expMethods) == 0
}
type maptype struct {
@ -664,13 +676,15 @@ func typesEqual(t, v *_type, seen map[_typePair]struct{}) bool {
if it.pkgpath.name() != iv.pkgpath.name() {
return false
}
if len(it.mhdr) != len(iv.mhdr) {
itmethods := it.methods()
ivmethods := iv.methods()
if len(itmethods) != len(ivmethods) {
return false
}
for i := range it.mhdr {
tm := &it.mhdr[i]
vm := &iv.mhdr[i]
// Note the mhdr array can be relocated from
for i := range itmethods {
tm := &itmethods[i]
vm := &ivmethods[i]
// Note the expMethods array can be relocated from
// another module. See #17724.
tname := resolveNameOff(unsafe.Pointer(tm), tm.name)
vname := resolveNameOff(unsafe.Pointer(vm), vm.name)