cmd/compile/internal/typecheck: remove some un-used functions

CL 405094 removed the only caller of markBreak/setHasBreak and
isTermNodes/isTermNode.

importlist variable is only used in old frontend.

Change-Id: I9472f2c0017b6200847999f2cea0e9021a1b14e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/484435
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>
Reviewed-by: Keith Randall <[email protected]>

Author: cuonglm

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

@@ -46,8 +46,6 @@ func Callee(n ir.Node) ir.Node {
 	return typecheck(n, ctxExpr|ctxCallee)
 }
 
-var importlist []*ir.Func
-
 var traceIndent []byte
 
 func tracePrint(title string, n ir.Node) func(np *ir.Node) {
@@ -1674,147 +1672,6 @@ func checkunsafesliceorstring(op ir.Op, np *ir.Node) bool {
 	return true
 }
 
-// markBreak marks control statements containing break statements with SetHasBreak(true).
-func markBreak(fn *ir.Func) {
-	var labels map[*types.Sym]ir.Node
-	var implicit ir.Node
-
-	var mark func(ir.Node) bool
-	mark = func(n ir.Node) bool {
-		switch n.Op() {
-		default:
-			ir.DoChildren(n, mark)
-
-		case ir.OBREAK:
-			n := n.(*ir.BranchStmt)
-			if n.Label == nil {
-				setHasBreak(implicit)
-			} else {
-				setHasBreak(labels[n.Label])
-			}
-
-		case ir.OFOR, ir.OSWITCH, ir.OSELECT, ir.ORANGE:
-			old := implicit
-			implicit = n
-			var sym *types.Sym
-			switch n := n.(type) {
-			case *ir.ForStmt:
-				sym = n.Label
-			case *ir.RangeStmt:
-				sym = n.Label
-			case *ir.SelectStmt:
-				sym = n.Label
-			case *ir.SwitchStmt:
-				sym = n.Label
-			}
-			if sym != nil {
-				if labels == nil {
-					// Map creation delayed until we need it - most functions don't.
-					labels = make(map[*types.Sym]ir.Node)
-				}
-				labels[sym] = n
-			}
-			ir.DoChildren(n, mark)
-			if sym != nil {
-				delete(labels, sym)
-			}
-			implicit = old
-		}
-		return false
-	}
-
-	mark(fn)
-}
-
-func setHasBreak(n ir.Node) {
-	switch n := n.(type) {
-	default:
-		base.Fatalf("setHasBreak %+v", n.Op())
-	case nil:
-		// ignore
-	case *ir.ForStmt:
-		n.HasBreak = true
-	case *ir.RangeStmt:
-		n.HasBreak = true
-	case *ir.SelectStmt:
-		n.HasBreak = true
-	case *ir.SwitchStmt:
-		n.HasBreak = true
-	}
-}
-
-// isTermNodes reports whether the Nodes list ends with a terminating statement.
-func isTermNodes(l ir.Nodes) bool {
-	s := l
-	c := len(s)
-	if c == 0 {
-		return false
-	}
-	return isTermNode(s[c-1])
-}
-
-// isTermNode reports whether the node n, the last one in a
-// statement list, is a terminating statement.
-func isTermNode(n ir.Node) bool {
-	switch n.Op() {
-	// NOTE: OLABEL is treated as a separate statement,
-	// not a separate prefix, so skipping to the last statement
-	// in the block handles the labeled statement case by
-	// skipping over the label. No case OLABEL here.
-
-	case ir.OBLOCK:
-		n := n.(*ir.BlockStmt)
-		return isTermNodes(n.List)
-
-	case ir.OGOTO, ir.ORETURN, ir.OTAILCALL, ir.OPANIC, ir.OFALL:
-		return true
-
-	case ir.OFOR:
-		n := n.(*ir.ForStmt)
-		if n.Cond != nil {
-			return false
-		}
-		if n.HasBreak {
-			return false
-		}
-		return true
-
-	case ir.OIF:
-		n := n.(*ir.IfStmt)
-		return isTermNodes(n.Body) && isTermNodes(n.Else)
-
-	case ir.OSWITCH:
-		n := n.(*ir.SwitchStmt)
-		if n.HasBreak {
-			return false
-		}
-		def := false
-		for _, cas := range n.Cases {
-			if !isTermNodes(cas.Body) {
-				return false
-			}
-			if len(cas.List) == 0 { // default
-				def = true
-			}
-		}
-		return def
-
-	case ir.OSELECT:
-		n := n.(*ir.SelectStmt)
-		if n.HasBreak {
-			return false
-		}
-		for _, cas := range n.Cases {
-			if !isTermNodes(cas.Body) {
-				return false
-			}
-		}
-		return true
-	}
-
-	return false
-}
-
 func Conv(n ir.Node, t *types.Type) ir.Node {
 	if types.IdenticalStrict(n.Type(), t) {
 		return n