1 files changed, 35 insertions, 32 deletions

diff --git a/libgo/go/debug/dwarf/unit.go b/libgo/go/debug/dwarf/unit.go
index be6093519d5..ceb6cdbff32 100644
--- a/libgo/go/debug/dwarf/unit.go
+++ b/libgo/go/debug/dwarf/unit.go
@@ -4,23 +4,22 @@
 
 package dwarf
 
-import "strconv"
+import (
+	"sort"
+	"strconv"
+)
 
 // DWARF debug info is split into a sequence of compilation units.
 // Each unit has its own abbreviation table and address size.
 
 type unit struct {
-	base    Offset // byte offset of header within the aggregate info
-	off     Offset // byte offset of data within the aggregate info
-	lineoff Offset // byte offset of data within the line info
-	data    []byte
-	atable  abbrevTable
-	asize   int
-	vers    int
-	is64    bool // True for 64-bit DWARF format
-	dir     string
-	pc      []addrRange   // PC ranges in this compilation unit
-	lines   []mapLineInfo // PC -> line mapping
+	base   Offset // byte offset of header within the aggregate info
+	off    Offset // byte offset of data within the aggregate info
+	data   []byte
+	atable abbrevTable
+	asize  int
+	vers   int
+	is64   bool // True for 64-bit DWARF format
 }
 
 // Implement the dataFormat interface.
@@ -37,25 +36,15 @@ func (u *unit) addrsize() int {
 	return u.asize
 }
 
-// A range is an address range.
-type addrRange struct {
-	low  uint64
-	high uint64
-}
-
 func (d *Data) parseUnits() ([]unit, error) {
 	// Count units.
 	nunit := 0
 	b := makeBuf(d, unknownFormat{}, "info", 0, d.info)
 	for len(b.data) > 0 {
-		len := b.uint32()
-		if len == 0xffffffff {
-			len64 := b.uint64()
-			if len64 != uint64(uint32(len64)) {
-				b.error("unit length overflow")
-				break
-			}
-			len = uint32(len64)
+		len, _ := b.unitLength()
+		if len != Offset(uint32(len)) {
+			b.error("unit length overflow")
+			break
 		}
 		b.skip(int(len))
 		nunit++
@@ -70,18 +59,15 @@ func (d *Data) parseUnits() ([]unit, error) {
 	for i := range units {
 		u := &units[i]
 		u.base = b.off
-		n := b.uint32()
-		if n == 0xffffffff {
-			u.is64 = true
-			n = uint32(b.uint64())
-		}
+		var n Offset
+		n, u.is64 = b.unitLength()
 		vers := b.uint16()
 		if vers != 2 && vers != 3 && vers != 4 {
 			b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
 			break
 		}
 		u.vers = int(vers)
-		atable, err := d.parseAbbrev(b.uint32())
+		atable, err := d.parseAbbrev(b.uint32(), u.vers)
 		if err != nil {
 			if b.err == nil {
 				b.err = err
@@ -98,3 +84,20 @@ func (d *Data) parseUnits() ([]unit, error) {
 	}
 	return units, nil
 }
+
+// offsetToUnit returns the index of the unit containing offset off.
+// It returns -1 if no unit contains this offset.
+func (d *Data) offsetToUnit(off Offset) int {
+	// Find the unit after off
+	next := sort.Search(len(d.unit), func(i int) bool {
+		return d.unit[i].off > off
+	})
+	if next == 0 {
+		return -1
+	}
+	u := &d.unit[next-1]
+	if u.off <= off && off < u.off+Offset(len(u.data)) {
+		return next - 1
+	}
+	return -1
+}