diff --git a/src/cmd/compile/internal/gc/dwinl.go b/src/cmd/compile/internal/gc/dwinl.go
index 33c8c8b058..f514281061 100644
--- a/src/cmd/compile/internal/gc/dwinl.go
+++ b/src/cmd/compile/internal/gc/dwinl.go
@@ -100,8 +100,8 @@ func assembleInlines(fnsym *obj.LSym, dwVars []*dwarf.Var) dwarf.InlCalls {
 		var m map[varPos]int
 		if ii == 0 {
 			if !fnsym.WasInlined() {
-				for j := 0; j < len(sl); j++ {
-					sl[j].ChildIndex = int32(j)
+				for j, v := range sl {
+					v.ChildIndex = int32(j)
 				}
 				continue
 			}
@@ -121,19 +121,19 @@ func assembleInlines(fnsym *obj.LSym, dwVars []*dwarf.Var) dwarf.InlCalls {
 		// parented by the inlined routine and not the top-level
 		// caller.
 		synthCount := len(m)
-		for j := 0; j < len(sl); j++ {
-			canonName := unversion(sl[j].Name)
+		for _, v := range sl {
+			canonName := unversion(v.Name)
 			vp := varPos{
 				DeclName: canonName,
-				DeclFile: sl[j].DeclFile,
-				DeclLine: sl[j].DeclLine,
-				DeclCol:  sl[j].DeclCol,
+				DeclFile: v.DeclFile,
+				DeclLine: v.DeclLine,
+				DeclCol:  v.DeclCol,
 			}
-			synthesized := strings.HasPrefix(sl[j].Name, "~r") || canonName == "_"
+			synthesized := strings.HasPrefix(v.Name, "~r") || canonName == "_"
 			if idx, found := m[vp]; found {
-				sl[j].ChildIndex = int32(idx)
-				sl[j].IsInAbstract = !synthesized
-				sl[j].Name = canonName
+				v.ChildIndex = int32(idx)
+				v.IsInAbstract = !synthesized
+				v.Name = canonName
 			} else {
 				// Variable can't be found in the pre-inline dcl list.
 				// In the top-level case (ii=0) this can happen
@@ -141,7 +141,7 @@ func assembleInlines(fnsym *obj.LSym, dwVars []*dwarf.Var) dwarf.InlCalls {
 				// and we're looking at a piece. We can also see
 				// return temps (~r%d) that were created during
 				// lowering, or unnamed params ("_").
-				sl[j].ChildIndex = int32(synthCount)
+				v.ChildIndex = int32(synthCount)
 				synthCount += 1
 			}
 		}
@@ -215,8 +215,7 @@ func unversion(name string) string {
 func makePreinlineDclMap(fnsym *obj.LSym) map[varPos]int {
 	dcl := preInliningDcls(fnsym)
 	m := make(map[varPos]int)
-	for i := 0; i < len(dcl); i++ {
-		n := dcl[i]
+	for i, n := range dcl {
 		pos := Ctxt.InnermostPos(n.Pos)
 		vp := varPos{
 			DeclName: unversion(n.Sym.Name),
@@ -338,7 +337,7 @@ func (s byClassThenName) Less(i, j int) bool { return cmpDwarfVar(s[i], s[j]) }
 func (s byClassThenName) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
 func dumpInlCall(inlcalls dwarf.InlCalls, idx, ilevel int) {
-	for i := 0; i < ilevel; i += 1 {
+	for i := 0; i < ilevel; i++ {
 		Ctxt.Logf("  ")
 	}
 	ic := inlcalls.Calls[idx]
@@ -363,9 +362,8 @@ func dumpInlCall(inlcalls dwarf.InlCalls, idx, ilevel int) {
 }
 
 func dumpInlCalls(inlcalls dwarf.InlCalls) {
-	n := len(inlcalls.Calls)
-	for k := 0; k < n; k += 1 {
-		if inlcalls.Calls[k].Root {
+	for k, c := range inlcalls.Calls {
+		if c.Root {
 			dumpInlCall(inlcalls, k, 0)
 		}
 	}
diff --git a/src/cmd/compile/internal/gc/phi.go b/src/cmd/compile/internal/gc/phi.go
index b549f0ea6f..bd66568eed 100644
--- a/src/cmd/compile/internal/gc/phi.go
+++ b/src/cmd/compile/internal/gc/phi.go
@@ -241,7 +241,7 @@ func (s *phiState) insertVarPhis(n int, var_ *Node, defs []*ssa.Block, typ *type
 				v := c.NewValue0I(currentRoot.Pos, ssa.OpPhi, typ, int64(n)) // TODO: line number right?
 				// Note: we store the variable number in the phi's AuxInt field. Used temporarily by phi building.
 				s.s.addNamedValue(var_, v)
-				for i := 0; i < len(c.Preds); i++ {
+				for range c.Preds {
 					v.AddArg(s.placeholder) // Actual args will be filled in by resolveFwdRefs.
 				}
 				if debugPhi {
diff --git a/src/cmd/compile/internal/gc/plive.go b/src/cmd/compile/internal/gc/plive.go
index 60c726ff58..14e755e1b0 100644
--- a/src/cmd/compile/internal/gc/plive.go
+++ b/src/cmd/compile/internal/gc/plive.go
@@ -487,8 +487,8 @@ func (lv *Liveness) prologue() {
 
 		// Walk the block instructions forward to update avarinit bits.
 		// avarinit describes the effect at the end of the block, not the beginning.
-		for j := 0; j < len(b.Values); j++ {
-			pos, e := lv.valueEffects(b.Values[j])
+		for _, val := range b.Values {
+			pos, e := lv.valueEffects(val)
 			if e&varkill != 0 {
 				be.avarinit.Unset(pos)
 			}
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index b9bf1d34fb..a6231963cd 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -73,9 +73,9 @@ func flusherrors() {
 		return
 	}
 	sort.Stable(byPos(errors))
-	for i := 0; i < len(errors); i++ {
-		if i == 0 || errors[i].msg != errors[i-1].msg {
-			fmt.Printf("%s", errors[i].msg)
+	for i, err := range errors {
+		if i == 0 || err.msg != errors[i-1].msg {
+			fmt.Printf("%s", err.msg)
 		}
 	}
 	errors = errors[:0]