1 files changed, 29 insertions, 23 deletions

diff --git a/src/pkg/debug/dwarf/type.go b/src/pkg/debug/dwarf/type.go
index b64333ecc5..fa40b2bef1 100644
--- a/src/pkg/debug/dwarf/type.go
+++ b/src/pkg/debug/dwarf/type.go
@@ -118,7 +118,12 @@ func (t *ArrayType) String() string {
 	return "[" + strconv.FormatInt(t.Count, 10) + "]" + t.Type.String()
 }
 
-func (t *ArrayType) Size() int64 { return t.Count * t.Type.Size() }
+func (t *ArrayType) Size() int64 {
+	if t.Count == -1 {
+		return 0
+	}
+	return t.Count * t.Type.Size()
+}
 
 // A VoidType represents the C void type.
 type VoidType struct {
@@ -369,7 +374,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 		t.StrideBitSize, _ = e.Val(AttrStrideSize).(int64)
 
 		// Accumulate dimensions,
-		ndim := 0
+		var dims []int64
 		for kid := next(); kid != nil; kid = next() {
 			// TODO(rsc): Can also be TagEnumerationType
 			// but haven't seen that in the wild yet.
@@ -381,26 +386,24 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 					count, ok = kid.Val(AttrUpperBound).(int64)
 					if ok {
 						count++ // Length is one more than upper bound.
-					} else {
+					} else if len(dims) == 0 {
 						count = -1 // As in x[].
 					}
 				}
-				if ndim == 0 {
-					t.Count = count
-				} else {
-					// Multidimensional array.
-					// Create new array type underneath this one.
-					t.Type = &ArrayType{Type: t.Type, Count: count}
-				}
-				ndim++
+				dims = append(dims, count)
 			case TagEnumerationType:
 				err = DecodeError{name, kid.Offset, "cannot handle enumeration type as array bound"}
 				goto Error
 			}
 		}
-		if ndim == 0 {
+		if len(dims) == 0 {
 			// LLVM generates this for x[].
-			t.Count = -1
+			dims = []int64{-1}
+		}
+
+		t.Count = dims[0]
+		for i := len(dims) - 1; i >= 1; i-- {
+			t.Type = &ArrayType{Type: t.Type, Count: dims[i]}
 		}
 
 	case TagBaseType:
@@ -476,7 +479,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 		t.StructName, _ = e.Val(AttrName).(string)
 		t.Incomplete = e.Val(AttrDeclaration) != nil
 		t.Field = make([]*StructField, 0, 8)
-		var lastFieldType Type
+		var lastFieldType *Type
 		var lastFieldBitOffset int64
 		for kid := next(); kid != nil; kid = next() {
 			if kid.Tag == TagMember {
@@ -518,7 +521,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 					// (DWARF writes out 0-length arrays as if they were 1-length arrays.)
 					zeroArray(lastFieldType)
 				}
-				lastFieldType = f.Type
+				lastFieldType = &f.Type
 				lastFieldBitOffset = bito
 			}
 		}
@@ -667,13 +670,16 @@ Error:
 	return nil, err
 }
 
-func zeroArray(t Type) {
-	for {
-		at, ok := t.(*ArrayType)
-		if !ok {
-			break
-		}
-		at.Count = 0
-		t = at.Type
+func zeroArray(t *Type) {
+	if t == nil {
+		return
+	}
+	at, ok := (*t).(*ArrayType)
+	if !ok || at.Type.Size() == 0 {
+		return
 	}
+	// Make a copy to avoid invalidating typeCache.
+	tt := *at
+	tt.Count = 0
+	*t = &tt
 }