cmd/compile: avoid range over copy of array

Passes toostash-check.

Slightly reduce compiler binary size:

file    before    after     Δ       %
compile 21087288  21070776  -16512  -0.078%
total   131847020 131830508 -16512  -0.013%

file                      before    after     Δ       %
cmd/compile/internal/gc.a 9007472   8999640   -7832   -0.087%
total                     127117794 127109962 -7832   -0.006%

Change-Id: I4aadd68d0a7545770598bed9d3a4d05899b67b52
Reviewed-on: https://go-review.googlesource.com/c/go/+/205777
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -1371,7 +1371,7 @@ func (e *Escape) finish(fns []*Node) {
 		fn.Esc = EscFuncTagged
 
 		narg := 0
-		for _, fs := range types.RecvsParams {
+		for _, fs := range &types.RecvsParams {
 			for _, f := range fs(fn.Type).Fields().Slice() {
 				narg++
 				f.Note = e.paramTag(fn, narg, f)

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

@@ -954,7 +954,7 @@ func (w *exportWriter) funcExt(n *Node) {
 	w.symIdx(n.Sym)
 
 	// Escape analysis.
-	for _, fs := range types.RecvsParams {
+	for _, fs := range &types.RecvsParams {
 		for _, f := range fs(n.Type).FieldSlice() {
 			w.string(f.Note)
 		}

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

@@ -660,7 +660,7 @@ func (r *importReader) funcExt(n *Node) {
 	r.symIdx(n.Sym)
 
 	// Escape analysis.
-	for _, fs := range types.RecvsParams {
+	for _, fs := range &types.RecvsParams {
 		for _, f := range fs(n.Type).FieldSlice() {
 			f.Note = r.string()
 		}

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

@@ -1071,7 +1071,7 @@ func loadsys() {
 	typecheckok = true
 
 	typs := runtimeTypes()
-	for _, d := range runtimeDecls {
+	for _, d := range &runtimeDecls {
 		sym := Runtimepkg.Lookup(d.name)
 		typ := typs[d.typ]
 		switch d.tag {
@@ -1374,7 +1374,7 @@ var concurrentFlagOK = [256]bool{
 }
 
 func concurrentBackendAllowed() bool {
-	for i, x := range Debug {
+	for i, x := range &Debug {
 		if x != 0 && !concurrentFlagOK[i] {
 			return false
 		}

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

@@ -646,7 +646,7 @@ func (p *noder) expr(expr syntax.Expr) *Node {
 		}
 		n := p.nod(expr, op, p.expr(expr.X), nil)
 		var index [3]*Node
-		for i, x := range expr.Index {
+		for i, x := range &expr.Index {
 			if x != nil {
 				index[i] = p.expr(x)
 			}

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

@@ -419,7 +419,7 @@ func (lv *Liveness) regEffects(v *ssa.Value) (uevar, kill liveRegMask) {
 			if v.Type.Etype != types.TTUPLE {
 				v.Fatalf("location pair %s has non-tuple type %v", loc, v.Type)
 			}
-			for i, loc1 := range loc {
+			for i, loc1 := range &loc {
 				if loc1 == nil {
 					continue
 				}

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

@@ -3216,7 +3216,7 @@ func init() {
 	var p4 []*sys.Arch
 	var p8 []*sys.Arch
 	var lwatomics []*sys.Arch
-	for _, a := range sys.Archs {
+	for _, a := range &sys.Archs {
 		all = append(all, a)
 		if a.PtrSize == 4 {
 			p4 = append(p4, a)

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

@@ -66,7 +66,7 @@ var builtinFuncs = [...]struct {
 // isBuiltinFuncName reports whether name matches a builtin function
 // name.
 func isBuiltinFuncName(name string) bool {
-	for _, fn := range builtinFuncs {
+	for _, fn := range &builtinFuncs {
 		if fn.name == name {
 			return true
 		}
@@ -92,7 +92,7 @@ func initUniverse() {
 
 // lexinit initializes known symbols and the basic types.
 func lexinit() {
-	for _, s := range basicTypes {
+	for _, s := range &basicTypes {
 		etype := s.etype
 		if int(etype) >= len(types.Types) {
 			Fatalf("lexinit: %s bad etype", s.name)
@@ -111,13 +111,13 @@ func lexinit() {
 		asNode(s2.Def).Name = new(Name)
 	}
 
-	for _, s := range builtinFuncs {
+	for _, s := range &builtinFuncs {
 		s2 := builtinpkg.Lookup(s.name)
 		s2.Def = asTypesNode(newname(s2))
 		asNode(s2.Def).SetSubOp(s.op)
 	}
 
-	for _, s := range unsafeFuncs {
+	for _, s := range &unsafeFuncs {
 		s2 := unsafepkg.Lookup(s.name)
 		s2.Def = asTypesNode(newname(s2))
 		asNode(s2.Def).SetSubOp(s.op)
@@ -402,7 +402,7 @@ func lexinit1() {
 	dowidth(types.Runetype)
 
 	// backend-dependent builtin types (e.g. int).
-	for _, s := range typedefs {
+	for _, s := range &typedefs {
 		s1 := builtinpkg.Lookup(s.name)
 
 		sameas := s.sameas32