// pointers, usually for alignment."
	var originals []ir.Node
	var walk func(n ir.Node)
	walk = func(n ir.Node) {
		switch n.Op() {
		case ir.OADD:
			n := n.(*ir.BinaryExpr)
			walk(n.X)
			walk(n.Y)
		case ir.OSUB, ir.OANDNOT:
			n := n.(*ir.BinaryExpr)
			walk(n.X)
		case ir.OCONVNOP:
			n := n.(*ir.ConvExpr)
			if n.X.Type().IsUnsafePtr() {
				n.X = cheapExpr(n.X, init)

	case *ast.StarExpr: // possibly an embedded type literal
		r.filterType(nil, t.X)
	case *ast.UnaryExpr:
		if t.Op == token.TILDE { // approximation element
			r.filterType(nil, t.X)
		}
	case *ast.BinaryExpr:
		if t.Op == token.OR { // union
			r.filterType(nil, t.X)
			r.filterType(nil, t.Y)
		}
	case *ast.ArrayType:
		r.filterType(nil, t.Elt)
	case *ast.StructType:

// Expressions

func (p *parser) expr() Expr {
	if trace {
		defer p.trace("expr")()
	}

	return p.binaryExpr(nil, 0)
}

// Expression = UnaryExpr | Expression binary_op Expression .
func (p *parser) binaryExpr(x Expr, prec int) Expr {
	// don't trace binaryExpr - only leads to overly nested trace output

	if x == nil {
		x = p.unaryExpr()
	}

		return
	}
	if len(s) < 2 || s[0] == nil || s[0].Op() != ir.OAS || s[1] == nil || s[1].Op() != ir.OCOPY {
		return
	}

	as := s[0].(*ir.AssignStmt)
	cp := s[1].(*ir.BinaryExpr)
	if as.Y == nil || as.Y.Op() != ir.OMAKESLICE || ir.IsBlank(as.X) ||
		as.X.Op() != ir.ONAME || cp.X.Op() != ir.ONAME || cp.Y.Op() != ir.ONAME ||
		as.X.Name() != cp.X.Name() || cp.X.Name() == cp.Y.Name() {

	return true
}

// opName returns the name of the operation if x is an operation
// that might overflow; otherwise it returns the empty string.
func opName(e ast.Expr) string {
	switch e := e.(type) {
	case *ast.BinaryExpr:
		if int(e.Op) < len(op2str2) {
			return op2str2[e.Op]
		}
	case *ast.UnaryExpr:
		if int(e.Op) < len(op2str1) {
			return op2str1[e.Op]
		}
	}
	return ""
}

var op2str1 = [...]string{

		// so we ensure they are evaluated first.
		case ir.OADD, ir.OSUB, ir.OMUL, ir.ONEG:
			return ssagen.Arch.SoftFloat && isSoftFloat(n.Type())
		case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
			n := n.(*ir.BinaryExpr)
			return ssagen.Arch.SoftFloat && isSoftFloat(n.X.Type())
		case ir.OCONV:
			n := n.(*ir.ConvExpr)
			return ssagen.Arch.SoftFloat && (isSoftFloat(n.Type()) || isSoftFloat(n.X.Type()))

		case ir.OMIN, ir.OMAX:

//
//	init {
//	  n := len(a)
//	  if n > len(b) { n = len(b) }
//	  if a.ptr != b.ptr { memmove(a.ptr, b.ptr, n*sizeof(elem(a))) }
//	}
//	n;
//
// Also works if b is a string.
func walkCopy(n *ir.BinaryExpr, init *ir.Nodes, runtimecall bool) ir.Node {
	if n.X.Type().Elem().HasPointers() {
		ir.CurFunc.SetWBPos(n.Pos())
		fn := writebarrierfn("typedslicecopy", n.X.Type().Elem(), n.Y.Type().Elem())
		n.X = cheapExpr(n.X, init)

		}
		fmt.Fprint(s, "]")

	case OSLICEHEADER:
		n := n.(*SliceHeaderExpr)
		fmt.Fprintf(s, "sliceheader{%v,%v,%v}", n.Ptr, n.Len, n.Cap)

	case OCOMPLEX, OCOPY, OUNSAFEADD, OUNSAFESLICE:
		n := n.(*BinaryExpr)
		fmt.Fprintf(s, "%v(%v, %v)", n.Op(), n.X, n.Y)

	case OCONV,
		OCONVIFACE,
		OCONVNOP,
		OBYTES2STR,
		ORUNES2STR,
		OSTR2BYTES,
		OSTR2RUNES,
		ORUNESTR,
		OSLICE2ARR,

func (p *parser) embeddedElem(x ast.Expr) ast.Expr {
	if p.trace {
		defer un(trace(p, "EmbeddedElem"))
	}
	if x == nil {
		x = p.embeddedTerm()
	}
	for p.tok == token.OR {
		t := new(ast.BinaryExpr)
		t.OpPos = p.pos
		t.Op = token.OR
		p.next()
		t.X = x
		t.Y = p.embeddedTerm()
		x = t
	}
	return x
}

func (p *parser) embeddedTerm() ast.Expr {
	if p.trace {

		} else {
			f.walk(&n.Fun, ctxCall, visit)
		}
		f.walk(n.Args, ctxExpr, visit)
	case *ast.StarExpr:
		f.walk(&n.X, context, visit)
	case *ast.UnaryExpr:
		f.walk(&n.X, ctxExpr, visit)
	case *ast.BinaryExpr:
		f.walk(&n.X, ctxExpr, visit)
		f.walk(&n.Y, ctxExpr, visit)
	case *ast.KeyValueExpr:
		f.walk(&n.Key, ctxExpr, visit)
		f.walk(&n.Value, ctxExpr, visit)

	case *ast.ArrayType: