cmd/compile: remove a few unnecessary gotos

Rework the logic to remove them. These were the low hanging fruit,
with labels that were used only once and logic that was fairly
straightforward.

Change-Id: I02a01c59c247b8b2972d8d73ff23f96f271de038
Reviewed-on: https://go-review.googlesource.com/63410
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -1165,19 +1165,17 @@ func dtypesym(t *types.Type) *types.Sym {
 		dupok = obj.DUPOK
 	}
 
-	if myimportpath == "runtime" && (tbase == types.Types[tbase.Etype] || tbase == types.Bytetype || tbase == types.Runetype || tbase == types.Errortype) { // int, float, etc
-		goto ok
-	}
-
+	if myimportpath != "runtime" || (tbase != types.Types[tbase.Etype] && tbase != types.Bytetype && tbase != types.Runetype && tbase != types.Errortype) { // int, float, etc
 		// named types from other files are defined only by those files
 		if tbase.Sym != nil && !tbase.Local() {
 			return s
 		}
+		// TODO(mdempsky): Investigate whether this can happen.
 		if isforw[tbase.Etype] {
 			return s
 		}
+	}
 
-ok:
 	ot := 0
 	lsym := s.Linksym()
 	switch t.Etype {

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

@@ -1847,11 +1847,12 @@ func implements(t, iface *types.Type, m, samename **types.Field, ptr *int) bool
 	// and then do one loop.
 
 	if t.IsInterface() {
+	Outer:
 		for _, im := range iface.Fields().Slice() {
 			for _, tm := range t.Fields().Slice() {
 				if tm.Sym == im.Sym {
 					if eqtype(tm.Type, im.Type) {
-						goto found
+						continue Outer
 					}
 					*m = im
 					*samename = tm
@@ -1864,7 +1865,6 @@ func implements(t, iface *types.Type, m, samename **types.Field, ptr *int) bool
 			*samename = nil
 			*ptr = 0
 			return false
-		found:
 		}
 
 		return true

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

@@ -621,6 +621,7 @@ func typecheck1(n *Node, top int) *Node {
 			// the only conversion that isn't a no-op is concrete == interface.
 			// in that case, check comparability of the concrete type.
 			// The conversion allocates, so only do it if the concrete type is huge.
+			converted := false
 			if r.Type.Etype != TBLANK {
 				aop = assignop(l.Type, r.Type, nil)
 				if aop != 0 {
@@ -639,11 +640,11 @@ func typecheck1(n *Node, top int) *Node {
 					}
 
 					t = r.Type
-					goto converted
+					converted = true
 				}
 			}
 
-			if l.Type.Etype != TBLANK {
+			if !converted && l.Type.Etype != TBLANK {
 				aop = assignop(r.Type, l.Type, nil)
 				if aop != 0 {
 					if l.Type.IsInterface() && !r.Type.IsInterface() && !IsComparable(r.Type) {
@@ -664,7 +665,6 @@ func typecheck1(n *Node, top int) *Node {
 				}
 			}
 
-		converted:
 			et = t.Etype
 		}
 

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

@@ -1999,8 +1999,6 @@ func mkdotargslice(typ *types.Type, args []*Node, init *Nodes, ddd *Node) *Node
 //	return expr-list
 //	func(expr-list)
 func ascompatte(call *Node, isddd bool, lhs *types.Type, rhs []*Node, fp int, init *Nodes) []*Node {
-	var nn []*Node
-
 	// f(g()) where g has multiple return values
 	if len(rhs) == 1 && rhs[0].Type.IsFuncArgStruct() {
 		// optimization - can do block copy
@@ -2008,8 +2006,9 @@ func ascompatte(call *Node, isddd bool, lhs *types.Type, rhs []*Node, fp int, in
 			nl := nodarg(lhs, fp)
 			nr := nod(OCONVNOP, rhs[0], nil)
 			nr.Type = nl.Type
-			nn = []*Node{convas(nod(OAS, nl, nr), init)}
-			goto ret
+			n := convas(nod(OAS, nl, nr), init)
+			n.SetTypecheck(1)
+			return []*Node{n}
 		}
 
 		// conversions involved.
@@ -2033,6 +2032,7 @@ func ascompatte(call *Node, isddd bool, lhs *types.Type, rhs []*Node, fp int, in
 	// If there's a ... parameter (which is only valid as the final
 	// parameter) and this is not a ... call expression,
 	// then assign the remaining arguments as a slice.
+	var nn []*Node
 	for i, nl := range lhs.FieldSlice() {
 		var nr *Node
 		if nl.Isddd() && !isddd {
@@ -2043,13 +2043,10 @@ func ascompatte(call *Node, isddd bool, lhs *types.Type, rhs []*Node, fp int, in
 
 		a := nod(OAS, nodarg(nl, fp), nr)
 		a = convas(a, init)
+		a.SetTypecheck(1)
 		nn = append(nn, a)
 	}
 
-ret:
-	for _, n := range nn {
-		n.SetTypecheck(1)
-	}
 	return nn
 }