1 files changed, 22 insertions, 17 deletions

diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index 9179b5490e..111a309eb5 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -298,7 +298,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 			continue
 		}
 
-		if goos == "darwin" && strings.HasSuffix(n.C, "Ref") {
+		if (goos == "darwin" || goos == "ios") && strings.HasSuffix(n.C, "Ref") {
 			// For FooRef, find out if FooGetTypeID exists.
 			s := n.C[:len(n.C)-3] + "GetTypeID"
 			n := &Name{Go: s, C: s}
@@ -2448,6 +2448,18 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 			tt := *t
 			tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}
 			tt.Go = c.Ident("struct{}")
+			if dt.Kind == "struct" {
+				// We don't know what the representation of this struct is, so don't let
+				// anyone allocate one on the Go side. As a side effect of this annotation,
+				// pointers to this type will not be considered pointers in Go. They won't
+				// get writebarrier-ed or adjusted during a stack copy. This should handle
+				// all the cases badPointerTypedef used to handle, but hopefully will
+				// continue to work going forward without any more need for cgo changes.
+				tt.NotInHeap = true
+				// TODO: we should probably do the same for unions. Unions can't live
+				// on the Go heap, right? It currently doesn't work for unions because
+				// they are defined as a type alias for struct{}, not a defined type.
+			}
 			typedef[name.Name] = &tt
 			break
 		}
@@ -2518,6 +2530,7 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 		}
 		t.Go = name
 		t.BadPointer = sub.BadPointer
+		t.NotInHeap = sub.NotInHeap
 		if unionWithPointer[sub.Go] {
 			unionWithPointer[t.Go] = true
 		}
@@ -2528,6 +2541,7 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 			tt := *t
 			tt.Go = sub.Go
 			tt.BadPointer = sub.BadPointer
+			tt.NotInHeap = sub.NotInHeap
 			typedef[name.Name] = &tt
 		}
 
@@ -2831,21 +2845,11 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
 		tgo := t.Go
 		size := t.Size
 		talign := t.Align
-		if f.BitSize > 0 {
-			switch f.BitSize {
-			case 8, 16, 32, 64:
-			default:
-				continue
-			}
-			size = f.BitSize / 8
-			name := tgo.(*ast.Ident).String()
-			if strings.HasPrefix(name, "int") {
-				name = "int"
-			} else {
-				name = "uint"
-			}
-			tgo = ast.NewIdent(name + fmt.Sprint(f.BitSize))
-			talign = size
+		if f.BitOffset > 0 || f.BitSize > 0 {
+			// The layout of bitfields is implementation defined,
+			// so we don't know how they correspond to Go fields
+			// even if they are aligned at byte boundaries.
+			continue
 		}
 
 		if talign > 0 && f.ByteOffset%talign != 0 {
@@ -3036,6 +3040,7 @@ func (c *typeConv) anonymousStructTypedef(dt *dwarf.TypedefType) bool {
 // non-pointers in this type.
 // TODO: Currently our best solution is to find these manually and list them as
 // they come up. A better solution is desired.
+// Note: DEPRECATED. There is now a better solution. Search for NotInHeap in this file.
 func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
 	if c.badCFType(dt) {
 		return true
@@ -3070,7 +3075,7 @@ func (c *typeConv) badCFType(dt *dwarf.TypedefType) bool {
 	// We identify the correct set of types as those ending in Ref and for which
 	// there exists a corresponding GetTypeID function.
 	// See comment below for details about the bad pointers.
-	if goos != "darwin" {
+	if goos != "darwin" && goos != "ios" {
 		return false
 	}
 	s := dt.Name