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reflect: ensure uniqueness of type descriptors on AIX. 

On AIX, duplication of type descriptors can occur if one is
declared in the libgo and one in the Go program being compiled.
The AIX linker isn't able to merge them together as Linux one does.
One solution is to always load libgo first but that needs a huge mechanism in
gcc core. Thus, this patch ensures that the duplication isn't visible
for the end user.

In reflect and internal/reflectlite, the comparison of rtypes is made on their
name and not only on their addresses.

In reflect, toType() function is using a canonicalization map to force rtypes
having the same rtype.String() to return the same Type. This can't be made in
internal/reflectlite as it needs sync package. But, for now, it doesn't matter
as internal/reflectlite is not widely used.

Fixes golang/go#39276

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/260158
This commit is contained in:
Clément Chigot 2020-10-07 15:47:45 +02:00 committed by Ian Lance Taylor
parent bdd74cc20c
commit 72b3833822
10 changed files with 168 additions and 30 deletions
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2
gcc/go/gofrontend/MERGE
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@ -1,4 +1,4 @@
2563706e4ead80d6906d66ae23c8915c360583ad
fef8afc1876f4a1d5e9a8fd54c21bf5917966e10
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.

6
libgo/Makefile.am
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@ -973,6 +973,12 @@ endif
# Also use -fno-inline to get better results from the memory profiler.
runtime_pprof_check_GOCFLAGS = -static-libgo -fno-inline
if LIBGO_IS_AIX
# reflect tests must be done with -static-libgo. Otherwize,
# there will be a duplication of the canonicalization map.
reflect_check_GOCFLAGS = -static-libgo -Wl,-bbigtoc
endif
if HAVE_STATIC_LINK
# Use -static for the syscall tests if possible, because otherwise when
# running as root the re-execs ignore LD_LIBRARY_PATH.

4
libgo/Makefile.in
View File

@ -1114,6 +1114,10 @@ runtime_internal_sys_lo_check_GOCFLAGS = -fgo-compiling-runtime
# Also use -fno-inline to get better results from the memory profiler.
runtime_pprof_check_GOCFLAGS = -static-libgo -fno-inline
# reflect tests must be done with -static-libgo. Otherwize,
# there will be a duplication of the canonicalization map.
@LIBGO_IS_AIX_TRUE@reflect_check_GOCFLAGS = -static-libgo -Wl,-bbigtoc
# Use -static for the syscall tests if possible, because otherwise when
# running as root the re-execs ignore LD_LIBRARY_PATH.
@HAVE_STATIC_LINK_TRUE@syscall_check_GOCFLAGS = -static

12
libgo/go/internal/reflectlite/eqtype.go Normal file
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@ -0,0 +1,12 @@
// Copyright 2020 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.
//+build !aix !gccgo
package reflectlite
// rtypeEqual returns true if both types are identical.
func rtypeEqual(t1, t2 *rtype) bool {
return t1 == t2
}

26
libgo/go/internal/reflectlite/eqtype_aix_gccgo.go Normal file
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@ -0,0 +1,26 @@
// Copyright 2020 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.
//+build aix,gccgo
// AIX linker isn't able to merge identical type descriptors coming from
// different objects. Thus, two rtypes might have two different pointers
// even if they are the same. Thus, instead of pointer equality, string
// field is checked.
package reflectlite
// rtypeEqual returns true if both types are identical.
func rtypeEqual(t1, t2 *rtype) bool {
switch {
case t1 == t2:
return true
case t1 == nil || t2 == nil:
return false
case t1.kind != t2.kind || t1.hash != t2.hash:
return false
default:
return t1.String() == t2.String()
}
}

8
libgo/go/internal/reflectlite/type.go
View File

@ -539,7 +539,7 @@ func implements(T, V *rtype) bool {
for j := 0; j < len(v.methods); j++ {
tm := &t.methods[i]
vm := &v.methods[j]
if *vm.name == *tm.name && (vm.pkgPath == tm.pkgPath || (vm.pkgPath != nil && tm.pkgPath != nil && *vm.pkgPath == *tm.pkgPath)) && toType(vm.typ).common() == toType(tm.typ).common() {
if *vm.name == *tm.name && (vm.pkgPath == tm.pkgPath || (vm.pkgPath != nil && tm.pkgPath != nil && *vm.pkgPath == *tm.pkgPath)) && rtypeEqual(toType(vm.typ).common(), toType(tm.typ).common()) {
if i++; i >= len(t.methods) {
return true
}
@ -556,7 +556,7 @@ func implements(T, V *rtype) bool {
for j := 0; j < len(v.methods); j++ {
tm := &t.methods[i]
vm := &v.methods[j]
if *vm.name == *tm.name && (vm.pkgPath == tm.pkgPath || (vm.pkgPath != nil && tm.pkgPath != nil && *vm.pkgPath == *tm.pkgPath)) && toType(vm.mtyp).common() == toType(tm.typ).common() {
if *vm.name == *tm.name && (vm.pkgPath == tm.pkgPath || (vm.pkgPath != nil && tm.pkgPath != nil && *vm.pkgPath == *tm.pkgPath)) && rtypeEqual(toType(vm.mtyp).common(), toType(tm.typ).common()) {
if i++; i >= len(t.methods) {
return true
}
@ -572,7 +572,7 @@ func implements(T, V *rtype) bool {
// and the ideal constant rules (no ideal constants at run time).
func directlyAssignable(T, V *rtype) bool {
// x's type V is identical to T?
if T == V {
if rtypeEqual(T, V) {
return true
}
@ -599,7 +599,7 @@ func haveIdenticalType(T, V Type, cmpTags bool) bool {
}
func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
if T == V {
if rtypeEqual(T, V) {
return true
}

24
libgo/go/reflect/eqtype.go Normal file
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@ -0,0 +1,24 @@
// Copyright 2020 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.
// +build !aix !gccgo
package reflect
// rtypeEqual returns true if both rtypes are identical.
func rtypeEqual(t1, t2 *rtype) bool {
return t1 == t2
}
// typeEqual returns true if both Types are identical.
func typeEqual(t1, t2 Type) bool {
return t1 == t2
}
func toType(p *rtype) Type {
if p == nil {
return nil
}
return p
}

74
libgo/go/reflect/eqtype_aix_gccgo.go Normal file
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@ -0,0 +1,74 @@
// Copyright 2020 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.
//+build aix,gccgo
// AIX linker isn't able to merge identical type descriptors coming from
// different objects. Thus, two rtypes might have two different pointers
// even if they are the same. Thus, instead of pointer equality, string
// field is checked.
package reflect
import (
"sync"
)
// rtypeEqual returns true if both rtypes are identical.
func rtypeEqual(t1, t2 *rtype) bool {
switch {
case t1 == t2:
return true
case t1 == nil || t2 == nil:
return false
case t1.kind != t2.kind || t1.hash != t2.hash:
return false
default:
return t1.String() == t2.String()
}
}
// typeEqual returns true if both Types are identical.
func typeEqual(t1, t2 Type) bool {
return rtypeEqual(t1.common(), t2.common())
}
// toType converts from a *rtype to a Type that can be returned
// to the client of package reflect. The only concern is that
// a nil *rtype must be replaced by a nil Type.
// On AIX, as type duplications can occur, it also ensure that
// multiple *rtype for the same type are coalesced into a single
// Type.
var canonicalType = make(map[string]Type)
var canonicalTypeLock sync.RWMutex
func canonicalize(t Type) Type {
if t == nil {
return nil
}
s := t.rawString()
canonicalTypeLock.RLock()
if r, ok := canonicalType[s]; ok {
canonicalTypeLock.RUnlock()
return r
}
canonicalTypeLock.RUnlock()
canonicalTypeLock.Lock()
if r, ok := canonicalType[s]; ok {
canonicalTypeLock.Unlock()
return r
}
canonicalType[s] = t
canonicalTypeLock.Unlock()
return t
}
func toType(p *rtype) Type {
if p == nil {
return nil
}
return canonicalize(p)
}

40
libgo/go/reflect/type.go
View File

@ -1129,7 +1129,7 @@ func (t *rtype) ptrTo() *rtype {
// Look in known types.
s := "*" + *t.string
if tt := lookupType(s); tt != nil {
p := (*ptrType)(unsafe.Pointer(tt))
p := (*ptrType)(unsafe.Pointer(toType(tt).(*rtype)))
if p.elem == t {
pi, _ := ptrMap.LoadOrStore(t, p)
return &pi.(*ptrType).rtype
@ -1158,7 +1158,9 @@ func (t *rtype) ptrTo() *rtype {
pp.ptrToThis = nil
pp.elem = t
pi, _ := ptrMap.LoadOrStore(t, &pp)
q := toType(&pp.rtype).(*rtype)
p := (*ptrType)(unsafe.Pointer(q))
pi, _ := ptrMap.LoadOrStore(t, p)
return &pi.(*ptrType).rtype
}
@ -1273,7 +1275,7 @@ func specialChannelAssignability(T, V *rtype) bool {
// and the ideal constant rules (no ideal constants at run time).
func directlyAssignable(T, V *rtype) bool {
// x's type V is identical to T?
if T == V {
if rtypeEqual(T, V) {
return true
}
@ -1304,7 +1306,7 @@ func haveIdenticalType(T, V Type, cmpTags bool) bool {
}
func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
if T == V {
if rtypeEqual(T, V) {
return true
}
@ -1449,7 +1451,7 @@ func ChanOf(dir ChanDir, t Type) Type {
s = "chan " + *typ.string
}
if tt := lookupType(s); tt != nil {
ch := (*chanType)(unsafe.Pointer(tt))
ch := (*chanType)(unsafe.Pointer(toType(tt).(*rtype)))
if ch.elem == typ && ch.dir == uintptr(dir) {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
@ -1481,7 +1483,7 @@ func ChanOf(dir ChanDir, t Type) Type {
ch.uncommonType = nil
ch.ptrToThis = nil
ti, _ := lookupCache.LoadOrStore(ckey, &ch.rtype)
ti, _ := lookupCache.LoadOrStore(ckey, toType(&ch.rtype).(*rtype))
return ti.(Type)
}
@ -1508,7 +1510,7 @@ func MapOf(key, elem Type) Type {
// Look in known types.
s := "map[" + *ktyp.string + "]" + *etyp.string
if tt := lookupType(s); tt != nil {
mt := (*mapType)(unsafe.Pointer(tt))
mt := (*mapType)(unsafe.Pointer(toType(tt).(*rtype)))
if mt.key == ktyp && mt.elem == etyp {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
@ -1559,7 +1561,7 @@ func MapOf(key, elem Type) Type {
mt.flags |= 16
}
ti, _ := lookupCache.LoadOrStore(ckey, &mt.rtype)
ti, _ := lookupCache.LoadOrStore(ckey, toType(&mt.rtype).(*rtype))
return ti.(Type)
}
@ -1648,7 +1650,7 @@ func FuncOf(in, out []Type, variadic bool) Type {
ft.string = &str
ft.uncommonType = nil
ft.ptrToThis = nil
return addToCache(&ft.rtype)
return addToCache(toType(&ft.rtype).(*rtype))
}
// funcStr builds a string representation of a funcType.
@ -1909,7 +1911,7 @@ func SliceOf(t Type) Type {
// Look in known types.
s := "[]" + *typ.string
if tt := lookupType(s); tt != nil {
slice := (*sliceType)(unsafe.Pointer(tt))
slice := (*sliceType)(unsafe.Pointer(toType(tt).(*rtype)))
if slice.elem == typ {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
@ -1930,7 +1932,7 @@ func SliceOf(t Type) Type {
slice.uncommonType = nil
slice.ptrToThis = nil
ti, _ := lookupCache.LoadOrStore(ckey, &slice.rtype)
ti, _ := lookupCache.LoadOrStore(ckey, toType(&slice.rtype).(*rtype))
return ti.(Type)
}
@ -2234,7 +2236,7 @@ func StructOf(fields []StructField) Type {
typ.uncommonType = nil
typ.ptrToThis = nil
return addToCache(&typ.rtype)
return addToCache(toType(&typ.rtype).(*rtype))
}
// runtimeStructField takes a StructField value passed to StructOf and
@ -2330,7 +2332,7 @@ func ArrayOf(count int, elem Type) Type {
// Look in known types.
s := "[" + strconv.Itoa(count) + "]" + *typ.string
if tt := lookupType(s); tt != nil {
array := (*arrayType)(unsafe.Pointer(tt))
array := (*arrayType)(unsafe.Pointer(toType(tt).(*rtype)))
if array.elem == typ {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
@ -2446,7 +2448,7 @@ func ArrayOf(count int, elem Type) Type {
array.kind &^= kindDirectIface
}
ti, _ := lookupCache.LoadOrStore(ckey, &array.rtype)
ti, _ := lookupCache.LoadOrStore(ckey, toType(&array.rtype).(*rtype))
return ti.(Type)
}
@ -2458,16 +2460,6 @@ func appendVarint(x []byte, v uintptr) []byte {
return x
}
// toType converts from a *rtype to a Type that can be returned
// to the client of package reflect. The only concern is that
// a nil *rtype must be replaced by a nil Type.
func toType(p *rtype) Type {
if p == nil {
return nil
}
return p
}
// Look up a compiler-generated type descriptor.
// Implemented in runtime.
func lookupType(s string) *rtype

2
libgo/go/reflect/value.go
View File

@ -1785,7 +1785,7 @@ type SliceHeader struct {
}
func typesMustMatch(what string, t1, t2 Type) {
if t1 != t2 {
if !typeEqual(t1, t2) {
panic(what + ": " + t1.String() + " != " + t2.String())
}
}