debug/dwarf: refactor entry DIE reading helper

Simplify the signature of the "entry()" buf method to accept a unit as
opposed to a collection of unit components (version, atable, etc). No
change in functionality, this is a pure refactoring that will be
needed in subsequent patch.

Change-Id: I688def34e39d36b6a62733bc73dc42b49f78ca41
Reviewed-on: https://go-review.googlesource.com/c/go/+/655975
Reviewed-by: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: David Chase <[email protected]>

Author: thanm

src/debug/dwarf/entry.go

@@ -407,7 +407,8 @@ type Offset uint32
 
 // Entry reads a single entry from buf, decoding
 // according to the given abbreviation table.
-func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry {
+func (b *buf) entry(cu *Entry, u *unit) *Entry {
+	atab, ubase, vers := u.atable, u.base, u.vers
 	off := b.off
 	id := uint32(b.uint())
 	if id == 0 {
@@ -884,7 +885,7 @@ func (r *Reader) Next() (*Entry, error) {
 		return nil, nil
 	}
 	u := &r.d.unit[r.unit]
-	e := r.b.entry(r.cu, u.atable, u.base, u.vers)
+	e := r.b.entry(r.cu, u)
 	if r.b.err != nil {
 		r.err = r.b.err
 		return nil, r.err
@@ -1091,7 +1092,7 @@ func (d *Data) baseAddressForEntry(e *Entry) (*Entry, uint64, error) {
 		}
 		u := &d.unit[i]
 		b := makeBuf(d, u, "info", u.off, u.data)
-		cu = b.entry(nil, u.atable, u.base, u.vers)
+		cu = b.entry(nil, u)
 		if b.err != nil {
 			return nil, 0, b.err
 		}

src/debug/dwarf/typeunit.go

@@ -137,7 +137,7 @@ func (tur *typeUnitReader) Next() (*Entry, error) {
 	if len(tur.tu.data) == 0 {
 		return nil, nil
 	}
-	e := tur.b.entry(nil, tur.tu.atable, tur.tu.base, tur.tu.vers)
+	e := tur.b.entry(nil, &tur.tu.unit)
 	if tur.b.err != nil {
 		tur.err = tur.b.err
 		return nil, tur.err