libgo: Merge to master revision 19184.

The next revision, 19185, renames several runtime files, and
will be handled in a separate change.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@211328 138bc75d-0d04-0410-961f-82ee72b054a4

26 files changed, 1146 insertions, 62 deletions

diff --git a/libgo/go/debug/dwarf/const.go b/libgo/go/debug/dwarf/const.go
index 68503c742f6..2aa0c270ff2 100644
--- a/libgo/go/debug/dwarf/const.go
+++ b/libgo/go/debug/dwarf/const.go
@@ -207,6 +207,7 @@ const (
 	formRef8        format = 0x14
 	formRefUdata    format = 0x15
 	formIndirect    format = 0x16
+	// The following are new in DWARF 4.
 	formSecOffset   format = 0x17
 	formExprloc     format = 0x18
 	formFlagPresent format = 0x19
@@ -264,15 +265,22 @@ const (
 	TagVariantPart            Tag = 0x33
 	TagVariable               Tag = 0x34
 	TagVolatileType           Tag = 0x35
-	TagDwarfProcedure         Tag = 0x36
-	TagRestrictType           Tag = 0x37
-	TagInterfaceType          Tag = 0x38
-	TagNamespace              Tag = 0x39
-	TagImportedModule         Tag = 0x3A
-	TagUnspecifiedType        Tag = 0x3B
-	TagPartialUnit            Tag = 0x3C
-	TagImportedUnit           Tag = 0x3D
-	TagMutableType            Tag = 0x3E
+	// The following are new in DWARF 3.
+	TagDwarfProcedure  Tag = 0x36
+	TagRestrictType    Tag = 0x37
+	TagInterfaceType   Tag = 0x38
+	TagNamespace       Tag = 0x39
+	TagImportedModule  Tag = 0x3A
+	TagUnspecifiedType Tag = 0x3B
+	TagPartialUnit     Tag = 0x3C
+	TagImportedUnit    Tag = 0x3D
+	TagMutableType     Tag = 0x3E // Later removed from DWARF.
+	TagCondition       Tag = 0x3F
+	TagSharedType      Tag = 0x40
+	// The following are new in DWARF 4.
+	TagTypeUnit            Tag = 0x41
+	TagRvalueReferenceType Tag = 0x42
+	TagTemplateAlias       Tag = 0x43
 )
 
 var tagNames = [...]string{
@@ -332,6 +340,11 @@ var tagNames = [...]string{
 	TagPartialUnit:            "PartialUnit",
 	TagImportedUnit:           "ImportedUnit",
 	TagMutableType:            "MutableType",
+	TagCondition:              "Condition",
+	TagSharedType:             "SharedType",
+	TagTypeUnit:               "TypeUnit",
+	TagRvalueReferenceType:    "RvalueReferenceType",
+	TagTemplateAlias:          "TemplateAlias",
 }
 
 func (t Tag) String() string {
diff --git a/libgo/go/debug/dwarf/entry.go b/libgo/go/debug/dwarf/entry.go
index e0d3229fb49..1772221633f 100644
--- a/libgo/go/debug/dwarf/entry.go
+++ b/libgo/go/debug/dwarf/entry.go
@@ -396,3 +396,15 @@ func (r *Reader) SkipChildren() {
 		}
 	}
 }
+
+// clone returns a copy of the reader.  This is used by the typeReader
+// interface.
+func (r *Reader) clone() typeReader {
+	return r.d.Reader()
+}
+
+// offset returns the current buffer offset.  This is used by the
+// typeReader interface.
+func (r *Reader) offset() Offset {
+	return r.b.off
+}
diff --git a/libgo/go/debug/dwarf/open.go b/libgo/go/debug/dwarf/open.go
index 75798925296..c1b3f37aca9 100644
--- a/libgo/go/debug/dwarf/open.go
+++ b/libgo/go/debug/dwarf/open.go
@@ -26,6 +26,7 @@ type Data struct {
 	abbrevCache map[uint32]abbrevTable
 	order       binary.ByteOrder
 	typeCache   map[Offset]Type
+	typeSigs    map[uint64]*typeUnit
 	unit        []unit
 }
 
@@ -49,6 +50,7 @@ func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Dat
 		str:         str,
 		abbrevCache: make(map[uint32]abbrevTable),
 		typeCache:   make(map[Offset]Type),
+		typeSigs:    make(map[uint64]*typeUnit),
 	}
 
 	// Sniff .debug_info to figure out byte order.
@@ -75,3 +77,11 @@ func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Dat
 	d.unit = u
 	return d, nil
 }
+
+// AddTypes will add one .debug_types section to the DWARF data.  A
+// typical object with DWARF version 4 debug info will have multiple
+// .debug_types sections.  The name is used for error reporting only,
+// and serves to distinguish one .debug_types section from another.
+func (d *Data) AddTypes(name string, types []byte) error {
+	return d.parseTypes(name, types)
+}
diff --git a/libgo/go/debug/dwarf/testdata/typedef.elf4 b/libgo/go/debug/dwarf/testdata/typedef.elf4
new file mode 100644
index 00000000000..3d5a5a1b162
--- /dev/null
+++ b/libgo/go/debug/dwarf/testdata/typedef.elf4
diff --git a/libgo/go/debug/dwarf/type.go b/libgo/go/debug/dwarf/type.go
index 1fbae6c144e..68866d0b7bf 100644
--- a/libgo/go/debug/dwarf/type.go
+++ b/libgo/go/debug/dwarf/type.go
@@ -251,23 +251,37 @@ func (t *TypedefType) String() string { return t.Name }
 
 func (t *TypedefType) Size() int64 { return t.Type.Size() }
 
+// typeReader is used to read from either the info section or the
+// types section.
+type typeReader interface {
+	Seek(Offset)
+	Next() (*Entry, error)
+	clone() typeReader
+	offset() Offset
+}
+
+// Type reads the type at off in the DWARF ``info'' section.
 func (d *Data) Type(off Offset) (Type, error) {
-	if t, ok := d.typeCache[off]; ok {
+	return d.readType("info", d.Reader(), off, d.typeCache)
+}
+
+// readType reads a type from r at off of name using and updating a
+// type cache.
+func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Offset]Type) (Type, error) {
+	if t, ok := typeCache[off]; ok {
 		return t, nil
 	}
-
-	r := d.Reader()
 	r.Seek(off)
 	e, err := r.Next()
 	if err != nil {
 		return nil, err
 	}
 	if e == nil || e.Offset != off {
-		return nil, DecodeError{"info", off, "no type at offset"}
+		return nil, DecodeError{name, off, "no type at offset"}
 	}
 
 	// Parse type from Entry.
-	// Must always set d.typeCache[off] before calling
+	// Must always set typeCache[off] before calling
 	// d.Type recursively, to handle circular types correctly.
 	var typ Type
 
@@ -290,7 +304,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 				return nil
 			}
 			if kid == nil {
-				err = DecodeError{"info", r.b.off, "unexpected end of DWARF entries"}
+				err = DecodeError{name, r.offset(), "unexpected end of DWARF entries"}
 				return nil
 			}
 			if kid.Tag == 0 {
@@ -313,15 +327,21 @@ func (d *Data) Type(off Offset) (Type, error) {
 	// Get Type referred to by Entry's AttrType field.
 	// Set err if error happens.  Not having a type is an error.
 	typeOf := func(e *Entry) Type {
-		toff, ok := e.Val(AttrType).(Offset)
-		if !ok {
+		tval := e.Val(AttrType)
+		var t Type
+		switch toff := tval.(type) {
+		case Offset:
+			if t, err = d.readType(name, r.clone(), toff, typeCache); err != nil {
+				return nil
+			}
+		case uint64:
+			if t, err = d.sigToType(toff); err != nil {
+				return nil
+			}
+		default:
 			// It appears that no Type means "void".
 			return new(VoidType)
 		}
-		var t Type
-		if t, err = d.Type(toff); err != nil {
-			return nil
-		}
 		return t
 	}
 
@@ -337,7 +357,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//	dimensions are in left to right order.
 		t := new(ArrayType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		if t.Type = typeOf(e); err != nil {
 			goto Error
 		}
@@ -363,7 +383,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 				}
 				ndim++
 			case TagEnumerationType:
-				err = DecodeError{"info", kid.Offset, "cannot handle enumeration type as array bound"}
+				err = DecodeError{name, kid.Offset, "cannot handle enumeration type as array bound"}
 				goto Error
 			}
 		}
@@ -383,12 +403,12 @@ func (d *Data) Type(off Offset) (Type, error) {
 		name, _ := e.Val(AttrName).(string)
 		enc, ok := e.Val(AttrEncoding).(int64)
 		if !ok {
-			err = DecodeError{"info", e.Offset, "missing encoding attribute for " + name}
+			err = DecodeError{name, e.Offset, "missing encoding attribute for " + name}
 			goto Error
 		}
 		switch enc {
 		default:
-			err = DecodeError{"info", e.Offset, "unrecognized encoding attribute value"}
+			err = DecodeError{name, e.Offset, "unrecognized encoding attribute value"}
 			goto Error
 
 		case encAddress:
@@ -408,7 +428,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		case encUnsignedChar:
 			typ = new(UcharType)
 		}
-		d.typeCache[off] = typ
+		typeCache[off] = typ
 		t := typ.(interface {
 			Basic() *BasicType
 		}).Basic()
@@ -433,7 +453,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		// There is much more to handle C++, all ignored for now.
 		t := new(StructType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		switch e.Tag {
 		case TagClassType:
 			t.Kind = "class"
@@ -453,12 +473,13 @@ func (d *Data) Type(off Offset) (Type, error) {
 				if f.Type = typeOf(kid); err != nil {
 					goto Error
 				}
-				if loc, ok := kid.Val(AttrDataMemberLoc).([]byte); ok {
+				switch loc := kid.Val(AttrDataMemberLoc).(type) {
+				case []byte:
 					// TODO: Should have original compilation
 					// unit here, not unknownFormat.
 					b := makeBuf(d, unknownFormat{}, "location", 0, loc)
 					if b.uint8() != opPlusUconst {
-						err = DecodeError{"info", kid.Offset, "unexpected opcode"}
+						err = DecodeError{name, kid.Offset, "unexpected opcode"}
 						goto Error
 					}
 					f.ByteOffset = int64(b.uint())
@@ -466,6 +487,8 @@ func (d *Data) Type(off Offset) (Type, error) {
 						err = b.err
 						goto Error
 					}
+				case int64:
+					f.ByteOffset = loc
 				}
 
 				haveBitOffset := false
@@ -502,7 +525,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//	AttrType: subtype
 		t := new(QualType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		if t.Type = typeOf(e); err != nil {
 			goto Error
 		}
@@ -526,7 +549,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//		AttrConstValue: value of constant
 		t := new(EnumType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		t.EnumName, _ = e.Val(AttrName).(string)
 		t.Val = make([]*EnumValue, 0, 8)
 		for kid := next(); kid != nil; kid = next() {
@@ -552,7 +575,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//	AttrAddrClass: address class [ignored]
 		t := new(PtrType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		if e.Val(AttrType) == nil {
 			t.Type = &VoidType{}
 			break
@@ -571,7 +594,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//	TagUnspecifiedParameter: final ...
 		t := new(FuncType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		if t.ReturnType = typeOf(e); err != nil {
 			goto Error
 		}
@@ -598,7 +621,7 @@ func (d *Data) Type(off Offset) (Type, error) {
 		//	AttrType: type definition [required]
 		t := new(TypedefType)
 		typ = t
-		d.typeCache[off] = t
+		typeCache[off] = t
 		t.Name, _ = e.Val(AttrName).(string)
 		t.Type = typeOf(e)
 	}
@@ -620,7 +643,7 @@ Error:
 	// If the parse fails, take the type out of the cache
 	// so that the next call with this offset doesn't hit
 	// the cache and return success.
-	delete(d.typeCache, off)
+	delete(typeCache, off)
 	return nil, err
 }
 
diff --git a/libgo/go/debug/dwarf/type_test.go b/libgo/go/debug/dwarf/type_test.go
index b5b255f6f4a..2cb85e74bb2 100644
--- a/libgo/go/debug/dwarf/type_test.go
+++ b/libgo/go/debug/dwarf/type_test.go
@@ -73,6 +73,8 @@ func TestTypedefsMachO(t *testing.T) {
 	testTypedefs(t, machoData(t, "testdata/typedef.macho"), "macho")
 }
 
+func TestTypedefsELFDwarf4(t *testing.T) { testTypedefs(t, elfData(t, "testdata/typedef.elf4"), "elf") }
+
 func testTypedefs(t *testing.T, d *Data, kind string) {
 	r := d.Reader()
 	seen := make(map[string]bool)
diff --git a/libgo/go/debug/dwarf/typeunit.go b/libgo/go/debug/dwarf/typeunit.go
new file mode 100644
index 00000000000..3fd1c9973e5
--- /dev/null
+++ b/libgo/go/debug/dwarf/typeunit.go
@@ -0,0 +1,166 @@
+// Copyright 2012 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.
+
+package dwarf
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Parse the type units stored in a DWARF4 .debug_types section.  Each
+// type unit defines a single primary type and an 8-byte signature.
+// Other sections may then use formRefSig8 to refer to the type.
+
+// The typeUnit format is a single type with a signature.  It holds
+// the same data as a compilation unit.
+type typeUnit struct {
+	unit
+	toff  Offset // Offset to signature type within data.
+	name  string // Name of .debug_type section.
+	cache Type   // Cache the type, nil to start.
+}
+
+// Parse a .debug_types section.
+func (d *Data) parseTypes(name string, types []byte) error {
+	b := makeBuf(d, unknownFormat{}, name, 0, types)
+	for len(b.data) > 0 {
+		base := b.off
+		dwarf64 := false
+		n := b.uint32()
+		if n == 0xffffffff {
+			n64 := b.uint64()
+			if n64 != uint64(uint32(n64)) {
+				b.error("type unit length overflow")
+				return b.err
+			}
+			n = uint32(n64)
+			dwarf64 = true
+		}
+		hdroff := b.off
+		vers := b.uint16()
+		if vers != 4 {
+			b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
+			return b.err
+		}
+		var ao uint32
+		if !dwarf64 {
+			ao = b.uint32()
+		} else {
+			ao64 := b.uint64()
+			if ao64 != uint64(uint32(ao64)) {
+				b.error("type unit abbrev offset overflow")
+				return b.err
+			}
+			ao = uint32(ao64)
+		}
+		atable, err := d.parseAbbrev(ao)
+		if err != nil {
+			return err
+		}
+		asize := b.uint8()
+		sig := b.uint64()
+
+		var toff uint32
+		if !dwarf64 {
+			toff = b.uint32()
+		} else {
+			to64 := b.uint64()
+			if to64 != uint64(uint32(to64)) {
+				b.error("type unit type offset overflow")
+				return b.err
+			}
+			toff = uint32(to64)
+		}
+
+		boff := b.off
+		d.typeSigs[sig] = &typeUnit{
+			unit: unit{
+				base:   base,
+				off:    boff,
+				data:   b.bytes(int(Offset(n) - (b.off - hdroff))),
+				atable: atable,
+				asize:  int(asize),
+				vers:   int(vers),
+				is64:   dwarf64,
+			},
+			toff: Offset(toff),
+			name: name,
+		}
+		if b.err != nil {
+			return b.err
+		}
+	}
+	return nil
+}
+
+// Return the type for a type signature.
+func (d *Data) sigToType(sig uint64) (Type, error) {
+	tu := d.typeSigs[sig]
+	if tu == nil {
+		return nil, fmt.Errorf("no type unit with signature %v", sig)
+	}
+	if tu.cache != nil {
+		return tu.cache, nil
+	}
+
+	b := makeBuf(d, tu, tu.name, tu.off, tu.data)
+	r := &typeUnitReader{d: d, tu: tu, b: b}
+	t, err := d.readType(tu.name, r, Offset(tu.toff), make(map[Offset]Type))
+	if err != nil {
+		return nil, err
+	}
+
+	tu.cache = t
+	return t, nil
+}
+
+// typeUnitReader is a typeReader for a tagTypeUnit.
+type typeUnitReader struct {
+	d   *Data
+	tu  *typeUnit
+	b   buf
+	err error
+}
+
+// Seek to a new position in the type unit.
+func (tur *typeUnitReader) Seek(off Offset) {
+	tur.err = nil
+	doff := off - tur.tu.off
+	if doff < 0 || doff >= Offset(len(tur.tu.data)) {
+		tur.err = fmt.Errorf("%s: offset %d out of range; max %d", tur.tu.name, doff, len(tur.tu.data))
+		return
+	}
+	tur.b = makeBuf(tur.d, tur.tu, tur.tu.name, off, tur.tu.data[doff:])
+}
+
+// Next reads the next Entry from the type unit.
+func (tur *typeUnitReader) Next() (*Entry, error) {
+	if tur.err != nil {
+		return nil, tur.err
+	}
+	if len(tur.tu.data) == 0 {
+		return nil, nil
+	}
+	e := tur.b.entry(tur.tu.atable, tur.tu.base)
+	if tur.b.err != nil {
+		tur.err = tur.b.err
+		return nil, tur.err
+	}
+	return e, nil
+}
+
+// clone returns a new reader for the type unit.
+func (tur *typeUnitReader) clone() typeReader {
+	return &typeUnitReader{
+		d:  tur.d,
+		tu: tur.tu,
+		b:  makeBuf(tur.d, tur.tu, tur.tu.name, tur.tu.off, tur.tu.data),
+	}
+}
+
+// offset returns the current offset.
+func (tur *typeUnitReader) offset() Offset {
+	return tur.b.off
+}
diff --git a/libgo/go/debug/dwarf/unit.go b/libgo/go/debug/dwarf/unit.go
index 8e09298a8b4..be6093519d5 100644
--- a/libgo/go/debug/dwarf/unit.go
+++ b/libgo/go/debug/dwarf/unit.go
@@ -76,7 +76,7 @@ func (d *Data) parseUnits() ([]unit, error) {
 			n = uint32(b.uint64())
 		}
 		vers := b.uint16()
-		if vers < 2 || vers > 4 {
+		if vers != 2 && vers != 3 && vers != 4 {
 			b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
 			break
 		}
diff --git a/libgo/go/debug/elf/elf_test.go b/libgo/go/debug/elf/elf_test.go
index 67b961b5c6c..e3c51bb717b 100644
--- a/libgo/go/debug/elf/elf_test.go
+++ b/libgo/go/debug/elf/elf_test.go
@@ -43,7 +43,7 @@ func TestNames(t *testing.T) {
 	for i, tt := range nameTests {
 		s := fmt.Sprint(tt.val)
 		if s != tt.str {
-			t.Errorf("#%d: want %q have %q", i, s, tt.str)
+			t.Errorf("#%d: Sprint(%d) = %q, want %q", i, tt.val, s, tt.str)
 		}
 	}
 }
diff --git a/libgo/go/debug/elf/file.go b/libgo/go/debug/elf/file.go
index 8023eb0a0b7..a98b469b330 100644
--- a/libgo/go/debug/elf/file.go
+++ b/libgo/go/debug/elf/file.go
@@ -76,6 +76,9 @@ type Section struct {
 func (s *Section) Data() ([]byte, error) {
 	dat := make([]byte, s.sr.Size())
 	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
 	return dat[0:n], err
 }
 
@@ -412,7 +415,7 @@ func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) {
 	if err != nil {
 		return nil, nil, errors.New("cannot load symbol section")
 	}
-	symtab := bytes.NewBuffer(data)
+	symtab := bytes.NewReader(data)
 	if symtab.Len()%Sym32Size != 0 {
 		return nil, nil, errors.New("length of symbol section is not a multiple of SymSize")
 	}
@@ -455,7 +458,7 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
 	if err != nil {
 		return nil, nil, errors.New("cannot load symbol section")
 	}
-	symtab := bytes.NewBuffer(data)
+	symtab := bytes.NewReader(data)
 	if symtab.Len()%Sym64Size != 0 {
 		return nil, nil, errors.New("length of symbol section is not a multiple of Sym64Size")
 	}
@@ -533,7 +536,7 @@ func (f *File) applyRelocationsAMD64(dst []byte, rels []byte) error {
 		return err
 	}
 
-	b := bytes.NewBuffer(rels)
+	b := bytes.NewReader(rels)
 	var rela Rela64
 
 	for b.Len() > 0 {
@@ -601,7 +604,44 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 	}
 
 	abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
-	return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
+	d, err := dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
+	if err != nil {
+		return nil, err
+	}
+
+	// Look for DWARF4 .debug_types sections.
+	for i, s := range f.Sections {
+		if s.Name == ".debug_types" {
+			b, err := s.Data()
+			if err != nil && uint64(len(b)) < s.Size {
+				return nil, err
+			}
+
+			for _, r := range f.Sections {
+				if r.Type != SHT_RELA && r.Type != SHT_REL {
+					continue
+				}
+				if int(r.Info) != i {
+					continue
+				}
+				rd, err := r.Data()
+				if err != nil {
+					return nil, err
+				}
+				err = f.applyRelocations(b, rd)
+				if err != nil {
+					return nil, err
+				}
+			}
+
+			err = d.AddTypes(fmt.Sprintf("types-%d", i), b)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return d, nil
 }
 
 // Symbols returns the symbol table for f.
diff --git a/libgo/go/debug/elf/testdata/hello.c b/libgo/go/debug/elf/testdata/hello.c
new file mode 100644
index 00000000000..34d9ee79234
--- /dev/null
+++ b/libgo/go/debug/elf/testdata/hello.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+void
+main(int argc, char *argv[])
+{
+	printf("hello, world\n");
+}
diff --git a/libgo/go/debug/goobj/read.go b/libgo/go/debug/goobj/read.go
index 3338c411dc3..f65abb6c273 100644
--- a/libgo/go/debug/goobj/read.go
+++ b/libgo/go/debug/goobj/read.go
@@ -72,6 +72,49 @@ const (
 	SHOSTOBJ
 )
 
+var symKindStrings = []string{
+	SBSS:              "SBSS",
+	SCONST:            "SCONST",
+	SDATA:             "SDATA",
+	SDYNIMPORT:        "SDYNIMPORT",
+	SELFROSECT:        "SELFROSECT",
+	SELFRXSECT:        "SELFRXSECT",
+	SELFSECT:          "SELFSECT",
+	SFILE:             "SFILE",
+	SFILEPATH:         "SFILEPATH",
+	SFUNCTAB:          "SFUNCTAB",
+	SGOFUNC:           "SGOFUNC",
+	SGOSTRING:         "SGOSTRING",
+	SHOSTOBJ:          "SHOSTOBJ",
+	SINITARR:          "SINITARR",
+	SMACHO:            "SMACHO",
+	SMACHOGOT:         "SMACHOGOT",
+	SMACHOINDIRECTGOT: "SMACHOINDIRECTGOT",
+	SMACHOINDIRECTPLT: "SMACHOINDIRECTPLT",
+	SMACHOPLT:         "SMACHOPLT",
+	SMACHOSYMSTR:      "SMACHOSYMSTR",
+	SMACHOSYMTAB:      "SMACHOSYMTAB",
+	SNOPTRBSS:         "SNOPTRBSS",
+	SNOPTRDATA:        "SNOPTRDATA",
+	SPCLNTAB:          "SPCLNTAB",
+	SRODATA:           "SRODATA",
+	SSTRING:           "SSTRING",
+	SSYMTAB:           "SSYMTAB",
+	STEXT:             "STEXT",
+	STLSBSS:           "STLSBSS",
+	STYPE:             "STYPE",
+	STYPELINK:         "STYPELINK",
+	SWINDOWS:          "SWINDOWS",
+	SXREF:             "SXREF",
+}
+
+func (k SymKind) String() string {
+	if k < 0 || int(k) >= len(symKindStrings) {
+		return fmt.Sprintf("SymKind(%d)", k)
+	}
+	return symKindStrings[k]
+}
+
 // A Sym is a named symbol in an object file.
 type Sym struct {
 	SymID         // symbol identifier (name and version)
@@ -98,6 +141,13 @@ type SymID struct {
 	Version int
 }
 
+func (s SymID) String() string {
+	if s.Version == 0 {
+		return s.Name
+	}
+	return fmt.Sprintf("%s<%d>", s.Name, s.Version)
+}
+
 // A Data is a reference to data stored in an object file.
 // It records the offset and size of the data, so that a client can
 // read the data only if necessary.
diff --git a/libgo/go/debug/gosym/pclntab.go b/libgo/go/debug/gosym/pclntab.go
index 3e6a8046b3e..6620aefb053 100644
--- a/libgo/go/debug/gosym/pclntab.go
+++ b/libgo/go/debug/gosym/pclntab.go
@@ -196,6 +196,33 @@ func (t *LineTable) go12Init() {
 	t.go12 = 1 // so far so good
 }
 
+// go12Funcs returns a slice of Funcs derived from the Go 1.2 pcln table.
+func (t *LineTable) go12Funcs() []Func {
+	// Assume it is malformed and return nil on error.
+	defer func() {
+		recover()
+	}()
+
+	n := len(t.functab) / int(t.ptrsize) / 2
+	funcs := make([]Func, n)
+	for i := range funcs {
+		f := &funcs[i]
+		f.Entry = uint64(t.uintptr(t.functab[2*i*int(t.ptrsize):]))
+		f.End = uint64(t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):]))
+		info := t.Data[t.uintptr(t.functab[(2*i+1)*int(t.ptrsize):]):]
+		f.LineTable = t
+		f.FrameSize = int(t.binary.Uint32(info[t.ptrsize+2*4:]))
+		f.Sym = &Sym{
+			Value:  f.Entry,
+			Type:   'T',
+			Name:   t.string(t.binary.Uint32(info[t.ptrsize:])),
+			GoType: 0,
+			Func:   f,
+		}
+	}
+	return funcs
+}
+
 // findFunc returns the func corresponding to the given program counter.
 func (t *LineTable) findFunc(pc uint64) []byte {
 	if pc < t.uintptr(t.functab) || pc >= t.uintptr(t.functab[len(t.functab)-int(t.ptrsize):]) {
diff --git a/libgo/go/debug/gosym/symtab.go b/libgo/go/debug/gosym/symtab.go
index 9ab05bac2f7..3864e3cb4fa 100644
--- a/libgo/go/debug/gosym/symtab.go
+++ b/libgo/go/debug/gosym/symtab.go
@@ -129,6 +129,9 @@ var (
 )
 
 func walksymtab(data []byte, fn func(sym) error) error {
+	if len(data) == 0 { // missing symtab is okay
+		return nil
+	}
 	var order binary.ByteOrder = binary.BigEndian
 	newTable := false
 	switch {
@@ -455,6 +458,10 @@ func NewTable(symtab []byte, pcln *LineTable) (*Table, error) {
 			i = end - 1 // loop will i++
 		}
 	}
+
+	if t.go12line != nil && nf == 0 {
+		t.Funcs = t.go12line.go12Funcs()
+	}
 	if obj != nil {
 		obj.Funcs = t.Funcs[lastf:]
 	}
diff --git a/libgo/go/debug/macho/fat.go b/libgo/go/debug/macho/fat.go
new file mode 100644
index 00000000000..93b8315263c
--- /dev/null
+++ b/libgo/go/debug/macho/fat.go
@@ -0,0 +1,146 @@
+// Copyright 2014 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.
+
+package macho
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+)
+
+// A FatFile is a Mach-O universal binary that contains at least one architecture.
+type FatFile struct {
+	Magic  uint32
+	Arches []FatArch
+	closer io.Closer
+}
+
+// A FatArchHeader represents a fat header for a specific image architecture.
+type FatArchHeader struct {
+	Cpu    Cpu
+	SubCpu uint32
+	Offset uint32
+	Size   uint32
+	Align  uint32
+}
+
+const fatArchHeaderSize = 5 * 4
+
+// A FatArch is a Mach-O File inside a FatFile.
+type FatArch struct {
+	FatArchHeader
+	*File
+}
+
+// ErrNotFat is returned from NewFatFile or OpenFat when the file is not a
+// universal binary but may be a thin binary, based on its magic number.
+var ErrNotFat = &FormatError{0, "not a fat Mach-O file", nil}
+
+// NewFatFile creates a new FatFile for accessing all the Mach-O images in a
+// universal binary. The Mach-O binary is expected to start at position 0 in
+// the ReaderAt.
+func NewFatFile(r io.ReaderAt) (*FatFile, error) {
+	var ff FatFile
+	sr := io.NewSectionReader(r, 0, 1<<63-1)
+
+	// Read the fat_header struct, which is always in big endian.
+	// Start with the magic number.
+	err := binary.Read(sr, binary.BigEndian, &ff.Magic)
+	if err != nil {
+		return nil, &FormatError{0, "error reading magic number", nil}
+	} else if ff.Magic != MagicFat {
+		// See if this is a Mach-O file via its magic number. The magic
+		// must be converted to little endian first though.
+		var buf [4]byte
+		binary.BigEndian.PutUint32(buf[:], ff.Magic)
+		leMagic := binary.LittleEndian.Uint32(buf[:])
+		if leMagic == Magic32 || leMagic == Magic64 {
+			return nil, ErrNotFat
+		} else {
+			return nil, &FormatError{0, "invalid magic number", nil}
+		}
+	}
+	offset := int64(4)
+
+	// Read the number of FatArchHeaders that come after the fat_header.
+	var narch uint32
+	err = binary.Read(sr, binary.BigEndian, &narch)
+	if err != nil {
+		return nil, &FormatError{offset, "invalid fat_header", nil}
+	}
+	offset += 4
+
+	if narch < 1 {
+		return nil, &FormatError{offset, "file contains no images", nil}
+	}
+
+	// Combine the Cpu and SubCpu (both uint32) into a uint64 to make sure
+	// there are not duplicate architectures.
+	seenArches := make(map[uint64]bool, narch)
+	// Make sure that all images are for the same MH_ type.
+	var machoType Type
+
+	// Following the fat_header comes narch fat_arch structs that index
+	// Mach-O images further in the file.
+	ff.Arches = make([]FatArch, narch)
+	for i := uint32(0); i < narch; i++ {
+		fa := &ff.Arches[i]
+		err = binary.Read(sr, binary.BigEndian, &fa.FatArchHeader)
+		if err != nil {
+			return nil, &FormatError{offset, "invalid fat_arch header", nil}
+		}
+		offset += fatArchHeaderSize
+
+		fr := io.NewSectionReader(r, int64(fa.Offset), int64(fa.Size))
+		fa.File, err = NewFile(fr)
+		if err != nil {
+			return nil, err
+		}
+
+		// Make sure the architecture for this image is not duplicate.
+		seenArch := (uint64(fa.Cpu) << 32) | uint64(fa.SubCpu)
+		if o, k := seenArches[seenArch]; o || k {
+			return nil, &FormatError{offset, fmt.Sprintf("duplicate architecture cpu=%v, subcpu=%#x", fa.Cpu, fa.SubCpu), nil}
+		}
+		seenArches[seenArch] = true
+
+		// Make sure the Mach-O type matches that of the first image.
+		if i == 0 {
+			machoType = fa.Type
+		} else {
+			if fa.Type != machoType {
+				return nil, &FormatError{offset, fmt.Sprintf("Mach-O type for architecture #%d (type=%#x) does not match first (type=%#x)", i, fa.Type, machoType), nil}
+			}
+		}
+	}
+
+	return &ff, nil
+}
+
+// OpenFat opens the named file using os.Open and prepares it for use as a Mach-O
+// universal binary.
+func OpenFat(name string) (ff *FatFile, err error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	ff, err = NewFatFile(f)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	ff.closer = f
+	return
+}
+
+func (ff *FatFile) Close() error {
+	var err error
+	if ff.closer != nil {
+		err = ff.closer.Close()
+		ff.closer = nil
+	}
+	return err
+}
diff --git a/libgo/go/debug/macho/file.go b/libgo/go/debug/macho/file.go
index 9d912e7a087..ed9b2a69120 100644
--- a/libgo/go/debug/macho/file.go
+++ b/libgo/go/debug/macho/file.go
@@ -74,6 +74,9 @@ type Segment struct {
 func (s *Segment) Data() ([]byte, error) {
 	dat := make([]byte, s.sr.Size())
 	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
 	return dat[0:n], err
 }
 
@@ -109,6 +112,9 @@ type Section struct {
 func (s *Section) Data() ([]byte, error) {
 	dat := make([]byte, s.sr.Size())
 	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
 	return dat[0:n], err
 }
 
@@ -246,7 +252,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdDylib:
 			var hdr DylibCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -263,7 +269,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSymtab:
 			var hdr SymtabCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -290,7 +296,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdDysymtab:
 			var hdr DysymtabCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -299,7 +305,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 				return nil, err
 			}
 			x := make([]uint32, hdr.Nindirectsyms)
-			if err := binary.Read(bytes.NewBuffer(dat), bo, x); err != nil {
+			if err := binary.Read(bytes.NewReader(dat), bo, x); err != nil {
 				return nil, err
 			}
 			st := new(Dysymtab)
@@ -311,7 +317,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSegment:
 			var seg32 Segment32
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &seg32); err != nil {
 				return nil, err
 			}
@@ -349,7 +355,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSegment64:
 			var seg64 Segment64
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &seg64); err != nil {
 				return nil, err
 			}
@@ -396,7 +402,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 func (f *File) parseSymtab(symdat, strtab, cmddat []byte, hdr *SymtabCmd, offset int64) (*Symtab, error) {
 	bo := f.ByteOrder
 	symtab := make([]Symbol, hdr.Nsyms)
-	b := bytes.NewBuffer(symdat)
+	b := bytes.NewReader(symdat)
 	for i := range symtab {
 		var n Nlist64
 		if f.Magic == Magic64 {
diff --git a/libgo/go/debug/macho/file_test.go b/libgo/go/debug/macho/file_test.go
index 640225b3291..0de9184c227 100644
--- a/libgo/go/debug/macho/file_test.go
+++ b/libgo/go/debug/macho/file_test.go
@@ -165,3 +165,46 @@ func TestOpenFailure(t *testing.T) {
 		t.Errorf("open %s: succeeded unexpectedly", filename)
 	}
 }
+
+func TestOpenFat(t *testing.T) {
+	ff, err := OpenFat("testdata/fat-gcc-386-amd64-darwin-exec")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if ff.Magic != MagicFat {
+		t.Errorf("OpenFat: got magic number %#x, want %#x", ff.Magic, MagicFat)
+	}
+	if len(ff.Arches) != 2 {
+		t.Errorf("OpenFat: got %d architectures, want 2", len(ff.Arches))
+	}
+
+	for i := range ff.Arches {
+		arch := &ff.Arches[i]
+		ftArch := &fileTests[i]
+
+		if arch.Cpu != ftArch.hdr.Cpu || arch.SubCpu != ftArch.hdr.SubCpu {
+			t.Error("OpenFat: architecture #%d got cpu=%#x subtype=%#x, expected cpu=%#x, subtype=%#x", i, arch.Cpu, arch.SubCpu, ftArch.hdr.Cpu, ftArch.hdr.SubCpu)
+		}
+
+		if !reflect.DeepEqual(arch.FileHeader, ftArch.hdr) {
+			t.Errorf("OpenFat header:\n\tgot %#v\n\twant %#v\n", arch.FileHeader, ftArch.hdr)
+		}
+	}
+}
+
+func TestOpenFatFailure(t *testing.T) {
+	filename := "file.go" // not a Mach-O file
+	if _, err := OpenFat(filename); err == nil {
+		t.Errorf("OpenFat %s: succeeded unexpectedly", filename)
+	}
+
+	filename = "testdata/gcc-386-darwin-exec" // not a fat Mach-O
+	ff, err := OpenFat(filename)
+	if err != ErrNotFat {
+		t.Errorf("OpenFat %s: got %v, want ErrNotFat", err)
+	}
+	if ff != nil {
+		t.Errorf("OpenFat %s: got %v, want nil", ff)
+	}
+}
diff --git a/libgo/go/debug/macho/macho.go b/libgo/go/debug/macho/macho.go
index bc14226c565..09f4d0ec91c 100644
--- a/libgo/go/debug/macho/macho.go
+++ b/libgo/go/debug/macho/macho.go
@@ -26,16 +26,19 @@ const (
 )
 
 const (
-	Magic32 uint32 = 0xfeedface
-	Magic64 uint32 = 0xfeedfacf
+	Magic32  uint32 = 0xfeedface
+	Magic64  uint32 = 0xfeedfacf
+	MagicFat uint32 = 0xcafebabe
 )
 
-// A Type is a Mach-O file type, either an object or an executable.
+// A Type is the Mach-O file type, e.g. an object file, executable, or dynamic library.
 type Type uint32
 
 const (
-	TypeObj  Type = 1
-	TypeExec Type = 2
+	TypeObj    Type = 1
+	TypeExec   Type = 2
+	TypeDylib  Type = 6
+	TypeBundle Type = 8
 )
 
 // A Cpu is a Mach-O cpu type.
diff --git a/libgo/go/debug/macho/testdata/fat-gcc-386-amd64-darwin-exec b/libgo/go/debug/macho/testdata/fat-gcc-386-amd64-darwin-exec
new file mode 100644
index 00000000000..7efd19300b2
--- /dev/null
+++ b/libgo/go/debug/macho/testdata/fat-gcc-386-amd64-darwin-exec
diff --git a/libgo/go/debug/pe/file.go b/libgo/go/debug/pe/file.go
index f521566efa7..d0005bacf38 100644
--- a/libgo/go/debug/pe/file.go
+++ b/libgo/go/debug/pe/file.go
@@ -72,6 +72,9 @@ type ImportDirectory struct {
 func (s *Section) Data() ([]byte, error) {
 	dat := make([]byte, s.sr.Size())
 	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
 	return dat[0:n], err
 }
 
@@ -213,15 +216,15 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		s := new(Section)
 		s.SectionHeader = SectionHeader{
 			Name:                 name,
-			VirtualSize:          uint32(sh.VirtualSize),
-			VirtualAddress:       uint32(sh.VirtualAddress),
-			Size:                 uint32(sh.SizeOfRawData),
-			Offset:               uint32(sh.PointerToRawData),
-			PointerToRelocations: uint32(sh.PointerToRelocations),
-			PointerToLineNumbers: uint32(sh.PointerToLineNumbers),
-			NumberOfRelocations:  uint16(sh.NumberOfRelocations),
-			NumberOfLineNumbers:  uint16(sh.NumberOfLineNumbers),
-			Characteristics:      uint32(sh.Characteristics),
+			VirtualSize:          sh.VirtualSize,
+			VirtualAddress:       sh.VirtualAddress,
+			Size:                 sh.SizeOfRawData,
+			Offset:               sh.PointerToRawData,
+			PointerToRelocations: sh.PointerToRelocations,
+			PointerToLineNumbers: sh.PointerToLineNumbers,
+			NumberOfRelocations:  sh.NumberOfRelocations,
+			NumberOfLineNumbers:  sh.NumberOfLineNumbers,
+			Characteristics:      sh.Characteristics,
 		}
 		s.sr = io.NewSectionReader(r, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
 		s.ReaderAt = s.sr
diff --git a/libgo/go/debug/plan9obj/file.go b/libgo/go/debug/plan9obj/file.go
new file mode 100644
index 00000000000..a4c95a92a5c
--- /dev/null
+++ b/libgo/go/debug/plan9obj/file.go
@@ -0,0 +1,346 @@
+// Copyright 2014 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.
+
+// Package plan9obj implements access to Plan 9 a.out object files.
+package plan9obj
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+)
+
+// A FileHeader represents an Plan 9 a.out file header.
+type FileHeader struct {
+	Ptrsz int
+}
+
+// A File represents an open Plan 9 a.out file.
+type File struct {
+	FileHeader
+	Sections []*Section
+	closer   io.Closer
+}
+
+type SectionHeader struct {
+	Name   string
+	Size   uint32
+	Offset uint32
+}
+
+// A Section represents a single section in an Plan 9 a.out file.
+type Section struct {
+	SectionHeader
+
+	// Embed ReaderAt for ReadAt method.
+	// Do not embed SectionReader directly
+	// to avoid having Read and Seek.
+	// If a client wants Read and Seek it must use
+	// Open() to avoid fighting over the seek offset
+	// with other clients.
+	io.ReaderAt
+	sr *io.SectionReader
+}
+
+// Data reads and returns the contents of the Plan 9 a.out section.
+func (s *Section) Data() ([]byte, error) {
+	dat := make([]byte, s.sr.Size())
+	n, err := s.sr.ReadAt(dat, 0)
+	return dat[0:n], err
+}
+
+// Open returns a new ReadSeeker reading the Plan 9 a.out section.
+func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }
+
+// A ProgHeader represents a single Plan 9 a.out program header.
+type ProgHeader struct {
+	Magic uint32
+	Text  uint32
+	Data  uint32
+	Bss   uint32
+	Syms  uint32
+	Entry uint64
+	Spsz  uint32
+	Pcsz  uint32
+}
+
+// A Prog represents the program header in an Plan 9 a.out binary.
+type Prog struct {
+	ProgHeader
+
+	// Embed ReaderAt for ReadAt method.
+	// Do not embed SectionReader directly
+	// to avoid having Read and Seek.
+	// If a client wants Read and Seek it must use
+	// Open() to avoid fighting over the seek offset
+	// with other clients.
+	io.ReaderAt
+	sr *io.SectionReader
+}
+
+// Open returns a new ReadSeeker reading the Plan 9 a.out program body.
+func (p *Prog) Open() io.ReadSeeker { return io.NewSectionReader(p.sr, 0, 1<<63-1) }
+
+// A Symbol represents an entry in a Plan 9 a.out symbol table section.
+type Sym struct {
+	Value uint64
+	Type  rune
+	Name  string
+}
+
+/*
+ * Plan 9 a.out reader
+ */
+
+type FormatError struct {
+	off int
+	msg string
+	val interface{}
+}
+
+func (e *FormatError) Error() string {
+	msg := e.msg
+	if e.val != nil {
+		msg += fmt.Sprintf(" '%v'", e.val)
+	}
+	msg += fmt.Sprintf(" in record at byte %#x", e.off)
+	return msg
+}
+
+// Open opens the named file using os.Open and prepares it for use as an Plan 9 a.out binary.
+func Open(name string) (*File, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	ff, err := NewFile(f)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	ff.closer = f
+	return ff, nil
+}
+
+// Close closes the File.
+// If the File was created using NewFile directly instead of Open,
+// Close has no effect.
+func (f *File) Close() error {
+	var err error
+	if f.closer != nil {
+		err = f.closer.Close()
+		f.closer = nil
+	}
+	return err
+}
+
+func parseMagic(magic [4]byte) (*ExecTable, error) {
+	for _, e := range exectab {
+		if string(magic[:]) == e.Magic {
+			return &e, nil
+		}
+	}
+	return nil, &FormatError{0, "bad magic number", magic[:]}
+}
+
+// NewFile creates a new File for accessing an Plan 9 binary in an underlying reader.
+// The Plan 9 binary is expected to start at position 0 in the ReaderAt.
+func NewFile(r io.ReaderAt) (*File, error) {
+	sr := io.NewSectionReader(r, 0, 1<<63-1)
+	// Read and decode Plan 9 magic
+	var magic [4]byte
+	if _, err := r.ReadAt(magic[:], 0); err != nil {
+		return nil, err
+	}
+	mp, err := parseMagic(magic)
+	if err != nil {
+		return nil, err
+	}
+
+	f := &File{FileHeader{mp.Ptrsz}, nil, nil}
+
+	ph := new(prog)
+	if err := binary.Read(sr, binary.BigEndian, ph); err != nil {
+		return nil, err
+	}
+
+	p := new(Prog)
+	p.ProgHeader = ProgHeader{
+		Magic: ph.Magic,
+		Text:  ph.Text,
+		Data:  ph.Data,
+		Bss:   ph.Bss,
+		Syms:  ph.Syms,
+		Entry: uint64(ph.Entry),
+		Spsz:  ph.Spsz,
+		Pcsz:  ph.Pcsz,
+	}
+
+	if mp.Ptrsz == 8 {
+		if err := binary.Read(sr, binary.BigEndian, &p.Entry); err != nil {
+			return nil, err
+		}
+	}
+
+	var sects = []struct {
+		name string
+		size uint32
+	}{
+		{"text", ph.Text},
+		{"data", ph.Data},
+		{"syms", ph.Syms},
+		{"spsz", ph.Spsz},
+		{"pcsz", ph.Pcsz},
+	}
+
+	f.Sections = make([]*Section, 5)
+
+	off := mp.Hsize
+
+	for i, sect := range sects {
+		s := new(Section)
+		s.SectionHeader = SectionHeader{
+			Name:   sect.name,
+			Size:   sect.size,
+			Offset: off,
+		}
+		off += sect.size
+		s.sr = io.NewSectionReader(r, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
+		s.ReaderAt = s.sr
+		f.Sections[i] = s
+	}
+
+	return f, nil
+}
+
+func walksymtab(data []byte, ptrsz int, fn func(sym) error) error {
+	var order binary.ByteOrder = binary.BigEndian
+	var s sym
+	p := data
+	for len(p) >= 4 {
+		// Symbol type, value.
+		if len(p) < ptrsz {
+			return &FormatError{len(data), "unexpected EOF", nil}
+		}
+		// fixed-width value
+		if ptrsz == 8 {
+			s.value = order.Uint64(p[0:8])
+			p = p[8:]
+		} else {
+			s.value = uint64(order.Uint32(p[0:4]))
+			p = p[4:]
+		}
+
+		var typ byte
+		typ = p[0] & 0x7F
+		s.typ = typ
+		p = p[1:]
+
+		// Name.
+		var i int
+		var nnul int
+		for i = 0; i < len(p); i++ {
+			if p[i] == 0 {
+				nnul = 1
+				break
+			}
+		}
+		switch typ {
+		case 'z', 'Z':
+			p = p[i+nnul:]
+			for i = 0; i+2 <= len(p); i += 2 {
+				if p[i] == 0 && p[i+1] == 0 {
+					nnul = 2
+					break
+				}
+			}
+		}
+		if len(p) < i+nnul {
+			return &FormatError{len(data), "unexpected EOF", nil}
+		}
+		s.name = p[0:i]
+		i += nnul
+		p = p[i:]
+
+		fn(s)
+	}
+	return nil
+}
+
+// NewTable decodes the Go symbol table in data,
+// returning an in-memory representation.
+func newTable(symtab []byte, ptrsz int) ([]Sym, error) {
+	var n int
+	err := walksymtab(symtab, ptrsz, func(s sym) error {
+		n++
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	fname := make(map[uint16]string)
+	syms := make([]Sym, 0, n)
+	err = walksymtab(symtab, ptrsz, func(s sym) error {
+		n := len(syms)
+		syms = syms[0 : n+1]
+		ts := &syms[n]
+		ts.Type = rune(s.typ)
+		ts.Value = s.value
+		switch s.typ {
+		default:
+			ts.Name = string(s.name[:])
+		case 'z', 'Z':
+			for i := 0; i < len(s.name); i += 2 {
+				eltIdx := binary.BigEndian.Uint16(s.name[i : i+2])
+				elt, ok := fname[eltIdx]
+				if !ok {
+					return &FormatError{-1, "bad filename code", eltIdx}
+				}
+				if n := len(ts.Name); n > 0 && ts.Name[n-1] != '/' {
+					ts.Name += "/"
+				}
+				ts.Name += elt
+			}
+		}
+		switch s.typ {
+		case 'f':
+			fname[uint16(s.value)] = ts.Name
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return syms, nil
+}
+
+// Symbols returns the symbol table for f.
+func (f *File) Symbols() ([]Sym, error) {
+	symtabSection := f.Section("syms")
+	if symtabSection == nil {
+		return nil, errors.New("no symbol section")
+	}
+
+	symtab, err := symtabSection.Data()
+	if err != nil {
+		return nil, errors.New("cannot load symbol section")
+	}
+
+	return newTable(symtab, f.Ptrsz)
+}
+
+// Section returns a section with the given name, or nil if no such
+// section exists.
+func (f *File) Section(name string) *Section {
+	for _, s := range f.Sections {
+		if s.Name == name {
+			return s
+		}
+	}
+	return nil
+}
diff --git a/libgo/go/debug/plan9obj/file_test.go b/libgo/go/debug/plan9obj/file_test.go
new file mode 100644
index 00000000000..cc1db409295
--- /dev/null
+++ b/libgo/go/debug/plan9obj/file_test.go
@@ -0,0 +1,81 @@
+// Copyright 2014 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.
+
+package plan9obj
+
+import (
+	"reflect"
+	"testing"
+)
+
+type fileTest struct {
+	file     string
+	hdr      FileHeader
+	sections []*SectionHeader
+}
+
+var fileTests = []fileTest{
+	{
+		"testdata/386-plan9-exec",
+		FileHeader{4},
+		[]*SectionHeader{
+			{"text", 0x4c5f, 0x20},
+			{"data", 0x94c, 0x4c7f},
+			{"syms", 0x2c2b, 0x55cb},
+			{"spsz", 0x0, 0x81f6},
+			{"pcsz", 0xf7a, 0x81f6},
+		},
+	},
+	{
+		"testdata/amd64-plan9-exec",
+		FileHeader{8},
+		[]*SectionHeader{
+			{"text", 0x4213, 0x28},
+			{"data", 0xa80, 0x423b},
+			{"syms", 0x2c8c, 0x4cbb},
+			{"spsz", 0x0, 0x7947},
+			{"pcsz", 0xca0, 0x7947},
+		},
+	},
+}
+
+func TestOpen(t *testing.T) {
+	for i := range fileTests {
+		tt := &fileTests[i]
+
+		f, err := Open(tt.file)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		if !reflect.DeepEqual(f.FileHeader, tt.hdr) {
+			t.Errorf("open %s:\n\thave %#v\n\twant %#v\n", tt.file, f.FileHeader, tt.hdr)
+			continue
+		}
+
+		for i, sh := range f.Sections {
+			if i >= len(tt.sections) {
+				break
+			}
+			have := &sh.SectionHeader
+			want := tt.sections[i]
+			if !reflect.DeepEqual(have, want) {
+				t.Errorf("open %s, section %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
+			}
+		}
+		tn := len(tt.sections)
+		fn := len(f.Sections)
+		if tn != fn {
+			t.Errorf("open %s: len(Sections) = %d, want %d", tt.file, fn, tn)
+		}
+	}
+}
+
+func TestOpenFailure(t *testing.T) {
+	filename := "file.go"    // not a Plan 9 a.out file
+	_, err := Open(filename) // don't crash
+	if err == nil {
+		t.Errorf("open %s: succeeded unexpectedly", filename)
+	}
+}
diff --git a/libgo/go/debug/plan9obj/plan9obj.go b/libgo/go/debug/plan9obj/plan9obj.go
new file mode 100644
index 00000000000..4e3b08f4164
--- /dev/null
+++ b/libgo/go/debug/plan9obj/plan9obj.go
@@ -0,0 +1,91 @@
+// Copyright 2014 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.
+
+/*
+ * Plan 9 a.out constants and data structures
+ */
+
+package plan9obj
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// Plan 9 Program header.
+type prog struct {
+	Magic uint32 /* magic number */
+	Text  uint32 /* size of text segment */
+	Data  uint32 /* size of initialized data */
+	Bss   uint32 /* size of uninitialized data */
+	Syms  uint32 /* size of symbol table */
+	Entry uint32 /* entry point */
+	Spsz  uint32 /* size of pc/sp offset table */
+	Pcsz  uint32 /* size of pc/line number table */
+}
+
+// Plan 9 symbol table entries.
+type sym struct {
+	value uint64
+	typ   byte
+	name  []byte
+}
+
+const (
+	hsize      = 4 * 8
+	_HDR_MAGIC = 0x00008000 /* header expansion */
+)
+
+func magic(f, b int) string {
+	buf := new(bytes.Buffer)
+	var i uint32 = uint32((f) | ((((4 * (b)) + 0) * (b)) + 7))
+	binary.Write(buf, binary.BigEndian, i)
+	return string(buf.Bytes())
+}
+
+var (
+	_A_MAGIC = magic(0, 8)           /* 68020 (retired) */
+	_I_MAGIC = magic(0, 11)          /* intel 386 */
+	_J_MAGIC = magic(0, 12)          /* intel 960 (retired) */
+	_K_MAGIC = magic(0, 13)          /* sparc */
+	_V_MAGIC = magic(0, 16)          /* mips 3000 BE */
+	_X_MAGIC = magic(0, 17)          /* att dsp 3210 (retired) */
+	_M_MAGIC = magic(0, 18)          /* mips 4000 BE */
+	_D_MAGIC = magic(0, 19)          /* amd 29000 (retired) */
+	_E_MAGIC = magic(0, 20)          /* arm */
+	_Q_MAGIC = magic(0, 21)          /* powerpc */
+	_N_MAGIC = magic(0, 22)          /* mips 4000 LE */
+	_L_MAGIC = magic(0, 23)          /* dec alpha (retired) */
+	_P_MAGIC = magic(0, 24)          /* mips 3000 LE */
+	_U_MAGIC = magic(0, 25)          /* sparc64 (retired) */
+	_S_MAGIC = magic(_HDR_MAGIC, 26) /* amd64 */
+	_T_MAGIC = magic(_HDR_MAGIC, 27) /* powerpc64 */
+	_R_MAGIC = magic(_HDR_MAGIC, 28) /* arm64 */
+)
+
+type ExecTable struct {
+	Magic string
+	Ptrsz int
+	Hsize uint32
+}
+
+var exectab = []ExecTable{
+	{_A_MAGIC, 4, hsize},
+	{_I_MAGIC, 4, hsize},
+	{_J_MAGIC, 4, hsize},
+	{_K_MAGIC, 4, hsize},
+	{_V_MAGIC, 4, hsize},
+	{_X_MAGIC, 4, hsize},
+	{_M_MAGIC, 4, hsize},
+	{_D_MAGIC, 4, hsize},
+	{_E_MAGIC, 4, hsize},
+	{_Q_MAGIC, 4, hsize},
+	{_N_MAGIC, 4, hsize},
+	{_L_MAGIC, 4, hsize},
+	{_P_MAGIC, 4, hsize},
+	{_U_MAGIC, 4, hsize},
+	{_S_MAGIC, 8, hsize + 8},
+	{_T_MAGIC, 8, hsize + 8},
+	{_R_MAGIC, 8, hsize + 8},
+}
diff --git a/libgo/go/debug/plan9obj/testdata/386-plan9-exec b/libgo/go/debug/plan9obj/testdata/386-plan9-exec
new file mode 100644
index 00000000000..748e83f8e6a
--- /dev/null
+++ b/libgo/go/debug/plan9obj/testdata/386-plan9-exec
diff --git a/libgo/go/debug/plan9obj/testdata/amd64-plan9-exec b/libgo/go/debug/plan9obj/testdata/amd64-plan9-exec
new file mode 100644
index 00000000000..3e257dd8ffc
--- /dev/null
+++ b/libgo/go/debug/plan9obj/testdata/amd64-plan9-exec
diff --git a/libgo/go/debug/plan9obj/testdata/hello.c b/libgo/go/debug/plan9obj/testdata/hello.c
new file mode 100644
index 00000000000..c0d633e29f0
--- /dev/null
+++ b/libgo/go/debug/plan9obj/testdata/hello.c
@@ -0,0 +1,8 @@
+#include <u.h>
+#include <libc.h>
+
+void
+main(void)
+{
+	print("hello, world\n");
+}