case *ast.LabeledStmt:
		return check.isTerminating(s.Stmt, s.Label.Name)

	case *ast.ExprStmt:
		// calling the predeclared (possibly parenthesized) panic() function is terminating
		if call, ok := ast.Unparen(s.X).(*ast.CallExpr); ok && check.isPanic[call] {
			return true
		}

	case *ast.ReturnStmt:
		return true

	case *ast.BranchStmt:
		if s.Tok == token.GOTO || s.Tok == token.FALLTHROUGH {
			return true
		}

// HasSideEffects reports whether evaluation of e has side effects.
func HasSideEffects(info *types.Info, e ast.Expr) bool {
	safe := true
	ast.Inspect(e, func(node ast.Node) bool {
		switch n := node.(type) {
		case *ast.CallExpr:
			typVal := info.Types[n.Fun]
			switch {
			case typVal.IsType():
				// Type conversion, which is safe.
			case typVal.IsBuiltin():
				// Builtin func, conservatively assumed to not
				// be safe for now.

		}
	}

	nodeFilter := []ast.Node{
		(*ast.ExprStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call, ok := astutil.Unparen(n.(*ast.ExprStmt).X).(*ast.CallExpr)
		if !ok {
			return // not a call statement
		}

		// Call to function or method?
		fn, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Func)
		if !ok {
			return // e.g. var or builtin
		}

				WriteExpr(buf, x.Max)
			}
		}
		buf.WriteByte(']')

	case *ast.TypeAssertExpr:
		WriteExpr(buf, x.X)
		buf.WriteString(".(")
		WriteExpr(buf, x.Type)
		buf.WriteByte(')')

	case *ast.CallExpr:
		WriteExpr(buf, x.Fun)
		buf.WriteByte('(')
		writeExprList(buf, x.Args)
		if hasDots(x) {
			buf.WriteString("...")
		}
		buf.WriteByte(')')

	case *ast.StarExpr:
		buf.WriteByte('*')

		}
		return stackTempAddr(init, t)
	}
	types.CalcSize(t)
	n.MarkNonNil()
	return n
}

func walkMinMax(n *ir.CallExpr, init *ir.Nodes) ir.Node {
	init.Append(ir.TakeInit(n)...)
	walkExprList(n.Args, init)
	return n
}

// generate code for print.
func walkPrint(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
	// Hoist all the argument evaluation up before the lock.
	walkExprListCheap(nn.Args, init)

	case *ast.BasicLit:
		return 1 << nBasicLit
	case *ast.BinaryExpr:
		return 1 << nBinaryExpr
	case *ast.BlockStmt:
		return 1 << nBlockStmt
	case *ast.BranchStmt:
		return 1 << nBranchStmt
	case *ast.CallExpr:
		return 1 << nCallExpr
	case *ast.CaseClause:
		return 1 << nCaseClause
	case *ast.ChanType:
		return 1 << nChanType
	case *ast.CommClause:
		return 1 << nCommClause
	case *ast.Comment:

}

func (check *Checker) assignError(rhs []ast.Expr, l, r int) {
	vars := measure(l, "variable")
	vals := measure(r, "value")
	rhs0 := rhs[0]

	if len(rhs) == 1 {
		if call, _ := ast.Unparen(rhs0).(*ast.CallExpr); call != nil {
			check.errorf(rhs0, WrongAssignCount, "assignment mismatch: %s but %s returns %s", vars, call.Fun, vals)
			return
		}
	}

func (check *Checker) assignError(rhs []syntax.Expr, l, r int) {
	vars := measure(l, "variable")
	vals := measure(r, "value")
	rhs0 := rhs[0]

	if len(rhs) == 1 {
		if call, _ := syntax.Unparen(rhs0).(*syntax.CallExpr); call != nil {
			check.errorf(rhs0, WrongAssignCount, "assignment mismatch: %s but %s returns %s", vars, call.Fun, vals)
			return
		}
	}

		}
		ir.Visit(n, c.findExtraCalls)
	}
	c.curfn = nil
	return c
}

func (c *nowritebarrierrecChecker) findExtraCalls(nn ir.Node) {
	if nn.Op() != ir.OCALLFUNC {
		return
	}
	n := nn.(*ir.CallExpr)
	if n.Fun == nil || n.Fun.Op() != ir.ONAME {
		return
	}
	fn := n.Fun.(*ir.Name)
	if fn.Class != ir.PFUNC || fn.Defn == nil {
		return
	}
	if types.RuntimeSymName(fn.Sym()) != "systemstack" {
		return
	}

package cfg

// This file implements the CFG construction pass.

import (
	"fmt"
	"go/ast"
	"go/token"
)

type builder struct {
	cfg       *CFG
	mayReturn func(*ast.CallExpr) bool
	current   *Block
	lblocks   map[string]*lblock // labeled blocks
	targets   *targets           // linked stack of branch targets
}

func (b *builder) stmt(_s ast.Stmt) {