3 files changed, 36 insertions, 11 deletions
diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go
index 6d5378200e..1238d4a053 100644
--- a/src/runtime/mfinal.go
+++ b/src/runtime/mfinal.go
@@ -331,10 +331,13 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 		throw("runtime.SetFinalizer: second argument is " + ftyp._string + ", not a function")
 	}
 	ft := (*functype)(unsafe.Pointer(ftyp))
-	if ft.dotdotdot || len(ft.in) != 1 {
+	if ft.dotdotdot() {
+		throw("runtime.SetFinalizer: cannot pass " + etyp._string + " to finalizer " + ftyp._string + " because dotdotdot")
+	}
+	if ft.dotdotdot() || ft.inCount != 1 {
 		throw("runtime.SetFinalizer: cannot pass " + etyp._string + " to finalizer " + ftyp._string)
 	}
-	fint := ft.in[0]
+	fint := ft.in()[0]
 	switch {
 	case fint == etyp:
 		// ok - same type
@@ -359,8 +362,8 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 okarg:
 	// compute size needed for return parameters
 	nret := uintptr(0)
-	for _, t := range ft.out {
-		nret = round(nret, uintptr(t.align)) + t.size
+	for _, t := range ft.out() {
+		nret = round(nret, uintptr(t.align)) + uintptr(t.size)
 	}
 	nret = round(nret, sys.PtrSize)
 
diff --git a/src/runtime/syscall_windows.go b/src/runtime/syscall_windows.go
index 081516c70a..ebfa32ff8c 100644
--- a/src/runtime/syscall_windows.go
+++ b/src/runtime/syscall_windows.go
@@ -45,15 +45,15 @@ func compileCallback(fn eface, cleanstack bool) (code uintptr) {
 		panic("compileCallback: not a function")
 	}
 	ft := (*functype)(unsafe.Pointer(fn._type))
-	if len(ft.out) != 1 {
+	if len(ft.out()) != 1 {
 		panic("compileCallback: function must have one output parameter")
 	}
 	uintptrSize := unsafe.Sizeof(uintptr(0))
-	if ft.out[0].size != uintptrSize {
+	if ft.out()[0].size != uintptrSize {
 		panic("compileCallback: output parameter size is wrong")
 	}
 	argsize := uintptr(0)
-	for _, t := range ft.in {
+	for _, t := range ft.in() {
 		if t.size > uintptrSize {
 			panic("compileCallback: input parameter size is wrong")
 		}
diff --git a/src/runtime/type.go b/src/runtime/type.go
index 9c9b5fb8cc..c504e2d294 100644
--- a/src/runtime/type.go
+++ b/src/runtime/type.go
@@ -128,6 +128,29 @@ func (t *_type) name() string {
 	return t._string[i+1:]
 }
 
+func (t *functype) in() []*_type {
+	// See funcType in reflect/type.go for details on data layout.
+	uadd := uintptr(unsafe.Sizeof(functype{}))
+	if t.typ.tflag&tflagUncommon != 0 {
+		uadd += unsafe.Sizeof(uncommontype{})
+	}
+	return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[:t.inCount]
+}
+
+func (t *functype) out() []*_type {
+	// See funcType in reflect/type.go for details on data layout.
+	uadd := uintptr(unsafe.Sizeof(functype{}))
+	if t.typ.tflag&tflagUncommon != 0 {
+		uadd += unsafe.Sizeof(uncommontype{})
+	}
+	outCount := t.outCount & (1<<15 - 1)
+	return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[t.inCount : t.inCount+outCount]
+}
+
+func (t *functype) dotdotdot() bool {
+	return t.outCount&(1<<15) != 0
+}
+
 type method struct {
 	name    *string
 	pkgpath *string
@@ -187,10 +210,9 @@ type slicetype struct {
 }
 
 type functype struct {
-	typ       _type
-	dotdotdot bool
-	in        []*_type
-	out       []*_type
+	typ      _type
+	inCount  uint16
+	outCount uint16
 }
 
 type ptrtype struct {