cmd/compile/internal/gc: various cleanups

Remove a couple of unnecessary var declarations, an unused sort.Sort
type, and simplify a range by using the two-name variant.

Change-Id: Ia251f634db0bfbe8b1d553b8659272ddbd13b2c3
Reviewed-on: https://go-review.googlesource.com/102336
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -465,8 +465,8 @@ func createComplexVars(fn *Func) ([]*Node, []*dwarf.Var, map[*Node]bool) {
 	var vars []*dwarf.Var
 	ssaVars := make(map[*Node]bool)
 
-	for varID := range debugInfo.Vars {
-		n := debugInfo.Vars[varID].(*Node)
+	for varID, dvar := range debugInfo.Vars {
+		n := dvar.(*Node)
 		ssaVars[n] = true
 		for _, slot := range debugInfo.VarSlots[varID] {
 			ssaVars[debugInfo.Slots[slot].N.(*Node)] = true

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

@@ -304,17 +304,16 @@ func affectedNode(v *ssa.Value) (*Node, ssa.SymEffect) {
 		return nil, 0
 	}
 
-	var n *Node
 	switch a := v.Aux.(type) {
 	case nil, *obj.LSym:
 		// ok, but no node
+		return nil, e
 	case *Node:
-		n = a
+		return a, e
 	default:
 		Fatalf("weird aux: %s", v.LongString())
+		return nil, e
 	}
-
-	return n, e
 }
 
 // Constructs a new liveness structure used to hold the global state of the

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

@@ -343,9 +343,8 @@ func methodfunc(f *types.Type, receiver *types.Type) *types.Type {
 		in = append(in, d)
 	}
 
-	var d *Node
 	for _, t := range f.Params().Fields().Slice() {
-		d = nod(ODCLFIELD, nil, nil)
+		d := nod(ODCLFIELD, nil, nil)
 		d.Type = t.Type
 		d.SetIsddd(t.Isddd())
 		in = append(in, d)
@@ -353,7 +352,7 @@ func methodfunc(f *types.Type, receiver *types.Type) *types.Type {
 
 	var out []*Node
 	for _, t := range f.Results().Fields().Slice() {
-		d = nod(ODCLFIELD, nil, nil)
+		d := nod(ODCLFIELD, nil, nil)
 		d.Type = t.Type
 		out = append(out, d)
 	}

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

@@ -113,14 +113,6 @@ func compactScopes(dwarfScopes []dwarf.Scope) []dwarf.Scope {
 	return dwarfScopes
 }
 
-type pcsByPC []scopedPCs
-
-func (s pcsByPC) Len() int      { return len(s) }
-func (s pcsByPC) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
-func (s pcsByPC) Less(i, j int) bool {
-	return s[i].start < s[j].start
-}
-
 type varsByScopeAndOffset struct {
 	vars   []*dwarf.Var
 	scopes []ScopeID