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

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 930339e9b44f06f0acc984992aae2fddc840cded..8f71939862b488181e7377dc3062ea5a347c2859 100644 (file)
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -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.

diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index e3f08a2df396cf42745419d172ea848616103354..76cdc8ef217d3fd662af0faaf6af2ca4195a0ac0 100644 (file)
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -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.

diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 18b1a06be4149cbae47005947528e79fcaf6de95..59a7083f6149a9a21be7eb9378575a0a662deddb 100644 (file)
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -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

diff --git a/libgo/go/internal/reflectlite/eqtype.go b/libgo/go/internal/reflectlite/eqtype.go
new file mode 100644 (file)
index 0000000..a03cf1c
--- /dev/null
+++ b/libgo/go/internal/reflectlite/eqtype.go
@@ -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
+}

diff --git a/libgo/go/internal/reflectlite/eqtype_aix_gccgo.go b/libgo/go/internal/reflectlite/eqtype_aix_gccgo.go
new file mode 100644 (file)
index 0000000..38b507f
--- /dev/null
+++ b/libgo/go/internal/reflectlite/eqtype_aix_gccgo.go
@@ -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()
+       }
+}

diff --git a/libgo/go/internal/reflectlite/type.go b/libgo/go/internal/reflectlite/type.go
index e700a554e4121f79b5dca3aa72fda892c6faf1bb..1609a06a53e15d26cde63d1c2252a77bcfe87df6 100644 (file)
--- a/libgo/go/internal/reflectlite/type.go
+++ b/libgo/go/internal/reflectlite/type.go
@@ -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
        }
 

diff --git a/libgo/go/reflect/eqtype.go b/libgo/go/reflect/eqtype.go
new file mode 100644 (file)
index 0000000..5639bc5
--- /dev/null
+++ b/libgo/go/reflect/eqtype.go
@@ -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
+}

diff --git a/libgo/go/reflect/eqtype_aix_gccgo.go b/libgo/go/reflect/eqtype_aix_gccgo.go
new file mode 100644 (file)
index 0000000..7afbf10
--- /dev/null
+++ b/libgo/go/reflect/eqtype_aix_gccgo.go
@@ -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)
+}

diff --git a/libgo/go/reflect/type.go b/libgo/go/reflect/type.go
index 2ce1901f5565a0266bd038499bbe0a7c2219eddb..73c09d4bb341037f8790ef8e7163437a602ed199 100644 (file)
--- a/libgo/go/reflect/type.go
+++ b/libgo/go/reflect/type.go
@@ -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

diff --git a/libgo/go/reflect/value.go b/libgo/go/reflect/value.go
index e60f84fe78d834f343319a39ab5d6750255b9922..64f74323160f4a761227a4912821cbda2064e7fe 100644 (file)
--- a/libgo/go/reflect/value.go
+++ b/libgo/go/reflect/value.go
@@ -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())
        }
 }