cmd/compile: remove itabEntry.sym

Follow-up to codereview feedback on CL 41409.

Passes toolstash-check.

Change-Id: Ica6658bdb8215fc4a0a30f41fe7bc8d9a8b109b4
Reviewed-on: https://go-review.googlesource.com/41412
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/reflect.go

@@ -18,15 +18,11 @@ import (
 
 type itabEntry struct {
 	t, itype *types.Type
-	sym      *types.Sym
-
-	// symbol of the itab itself;
-	// filled in lazily after typecheck
-	lsym *obj.LSym
+	lsym     *obj.LSym // symbol of the itab itself
 
 	// symbols of each method in
 	// the itab, sorted by byte offset;
-	// filled in at the same time as lsym
+	// filled in by peekitabs
 	entries []*obj.LSym
 }
 
@@ -961,8 +957,7 @@ func itabname(t, itype *types.Type) *Node {
 		n.Class = PEXTERN
 		n.Typecheck = 1
 		s.Def = asTypesNode(n)
-
-		itabs = append(itabs, itabEntry{t: t, itype: itype, sym: s})
+		itabs = append(itabs, itabEntry{t: t, itype: itype, lsym: s.Linksym()})
 	}
 
 	n := nod(OADDR, asNode(s.Def), nil)
@@ -1333,7 +1328,6 @@ func peekitabs() {
 		if len(methods) == 0 {
 			continue
 		}
-		tab.lsym = tab.sym.Linksym()
 		tab.entries = methods
 	}
 }
@@ -1441,19 +1435,18 @@ func dumptypestructs() {
 		//   unused [2]byte
 		//   fun    [1]uintptr // variable sized
 		// }
-		ilsym := i.sym.Linksym()
-		o := dsymptr(ilsym, 0, dtypesym(i.itype).Linksym(), 0)
-		o = dsymptr(ilsym, o, dtypesym(i.t).Linksym(), 0)
+		o := dsymptr(i.lsym, 0, dtypesym(i.itype).Linksym(), 0)
+		o = dsymptr(i.lsym, o, dtypesym(i.t).Linksym(), 0)
 		o += Widthptr                          // skip link field
-		o = duint32(ilsym, o, typehash(i.t))   // copy of type hash
+		o = duint32(i.lsym, o, typehash(i.t))  // copy of type hash
 		o += 4                                 // skip bad/inhash/unused fields
 		o += len(imethods(i.itype)) * Widthptr // skip fun method pointers
 		// at runtime the itab will contain pointers to types, other itabs and
 		// method functions. None are allocated on heap, so we can use obj.NOPTR.
-		ggloblsym(ilsym, int32(o), int16(obj.DUPOK|obj.NOPTR))
+		ggloblsym(i.lsym, int32(o), int16(obj.DUPOK|obj.NOPTR))
 
 		ilink := itablinkpkg.Lookup(i.t.ShortString() + "," + i.itype.ShortString()).Linksym()
-		dsymptr(ilink, 0, ilsym, 0)
+		dsymptr(ilink, 0, i.lsym, 0)
 		ggloblsym(ilink, int32(Widthptr), int16(obj.DUPOK|obj.RODATA))
 	}