debug/dwarf: compute ByteSize for more DWARF types
When a size attribute is not present for a type, we can still determine
the object size in some other cases: when the type is a Typedef
referring to another type, when the type embeds a Typedef, or when the
type is a pointer and we know the default address size.
Change-Id: Ie4ae12d1b968a6b8b4e37d13ffc7b479bc69b621
Reviewed-on: https://go-review.googlesource.com/10479
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/dwarf/entry.go b/dwarf/entry.go
index 665c684..4076ec1 100644
--- a/dwarf/entry.go
+++ b/dwarf/entry.go
@@ -292,6 +292,12 @@
return r
}
+// AddressSize returns the size in bytes of addresses in the current compilation
+// unit.
+func (r *Reader) AddressSize() int {
+ return r.d.unit[r.unit].asize
+}
+
// Seek positions the Reader at offset off in the encoded entry stream.
// Offset 0 can be used to denote the first entry.
func (r *Reader) Seek(off Offset) {
diff --git a/dwarf/type.go b/dwarf/type.go
index 134231f..a2471b6 100644
--- a/dwarf/type.go
+++ b/dwarf/type.go
@@ -335,6 +335,9 @@
Next() (*Entry, error)
clone() typeReader
offset() Offset
+ // AddressSize returns the size in bytes of addresses in the current
+ // compilation unit.
+ AddressSize() int
}
// Type reads the type at off in the DWARF ``info'' section.
@@ -358,6 +361,7 @@
if err != nil {
return nil, err
}
+ addressSize := r.AddressSize()
if e == nil || e.Offset != off {
return nil, DecodeError{name, off, "no type at offset"}
}
@@ -796,6 +800,18 @@
b, ok := e.Val(AttrByteSize).(int64)
if !ok {
b = -1
+ switch t := typ.(type) {
+ case *TypedefType:
+ b = t.Type.Size()
+ case *MapType:
+ b = t.Type.Size()
+ case *ChanType:
+ b = t.Type.Size()
+ case *InterfaceType:
+ b = t.Type.Size()
+ case *PtrType:
+ b = int64(addressSize)
+ }
}
typ.Common().ByteSize = b
}
diff --git a/dwarf/typeunit.go b/dwarf/typeunit.go
index 3fd1c99..d93b9f5 100644
--- a/dwarf/typeunit.go
+++ b/dwarf/typeunit.go
@@ -135,6 +135,11 @@
tur.b = makeBuf(tur.d, tur.tu, tur.tu.name, off, tur.tu.data[doff:])
}
+// AddressSize returns the size in bytes of addresses in the current type unit.
+func (tur *typeUnitReader) AddressSize() int {
+ return tur.tu.unit.asize
+}
+
// Next reads the next Entry from the type unit.
func (tur *typeUnitReader) Next() (*Entry, error) {
if tur.err != nil {
