return item.Slice(idx[0], idx[1]), nil
	}
	// given item[i:j:k], make sure i <= j <= k.
	if idx[1] > idx[2] {
		return reflect.Value{}, fmt.Errorf("invalid slice index: %d > %d", idx[1], idx[2])
	}
	return item.Slice3(idx[0], idx[1], idx[2]), nil
}

// Length

// length returns the length of the item, with an error if it has no defined length.
func length(item reflect.Value) (int, error) {
	item, isNil := indirect(item)

	fl := v.flag.ro() | flagIndir | flag(Slice)
	return Value{typ.Common(), unsafe.Pointer(&x), fl}
}

// Slice3 is the 3-index form of the slice operation: it returns v[i:j:k].
// It panics if v's Kind is not [Array] or [Slice], or if v is an unaddressable array,
// or if the indexes are out of bounds.
func (v Value) Slice3(i, j, k int) Value {
	var (
		cap  int
		typ  *sliceType
		base unsafe.Pointer
	)

	{name: "dot", format: "package main; var x = «x.»x"},
	{name: "index", format: "package main; var x = x«[1]»"},
	{name: "slice", format: "package main; var x = x«[1:2]»"},
	{name: "slice3", format: "package main; var x = x«[1:2:3]»"},
	{name: "dottype", format: "package main; var x = x«.(any)»"},
	{name: "callseq", format: "package main; var x = x«()»"},

	case ir.OSTRINGHEADER:
		n := n.(*ir.StringHeaderExpr)
		return tcStringHeader(n)

	case ir.OMAKESLICECOPY:
		n := n.(*ir.MakeExpr)
		return tcMakeSliceCopy(n)

	case ir.OSLICE, ir.OSLICE3:
		n := n.(*ir.SliceExpr)
		return tcSlice(n)

	// call and call like
	case ir.OCALL:
		n := n.(*ir.CallExpr)
		return tcCall(n, top)

	case ir.OCAP, ir.OLEN:
		n := n.(*ir.UnaryExpr)

		Lbrack token.Pos // position of "["
		Low    Expr      // begin of slice range; or nil
		High   Expr      // end of slice range; or nil
		Max    Expr      // maximum capacity of slice; or nil
		Slice3 bool      // true if 3-index slice (2 colons present)
		Rbrack token.Pos // position of "]"
	}

	// A TypeAssertExpr node represents an expression followed by a
	// type assertion.
	//
	TypeAssertExpr struct {

  // CHECK:      %[[SLICE3:.*]] = "tf.Slice"(%[[CONCAT]], %[[CST5]], %[[CST6]]) : (tensor<3x8x4xi32>, tensor<3xi64>, tensor<3xi64>) -> tensor<3x6x4xi32>
  // CHECK:      %[[CONCAT1:.*]] = "tf.ConcatV2"(%[[SLICE2]], %[[SLICE3]], %[[CST7]]) : (tensor<3x2x4xi32>, tensor<3x6x4xi32>, tensor<i32>) -> tensor<3x8x4xi32>

			o.exprList(n.Args)
		}

		if lhs == nil || lhs.Op() != ir.ONAME && !ir.SameSafeExpr(lhs, n.Args[0]) {
			return o.copyExpr(n)
		}
		return n

	case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
		n := n.(*ir.SliceExpr)
		n.X = o.expr(n.X, nil)
		n.Low = o.cheapExpr(o.expr(n.Low, nil))
		n.High = o.cheapExpr(o.expr(n.High, nil))
		n.Max = o.cheapExpr(o.expr(n.Max, nil))

  // CHECK: %[[SLICE3:.*]] = "mhlo.slice"(%{{.*}}) <{limit_indices = dense<[4, 3, 6]> : tensor<3xi64>, start_indices = dense<[0, 2, 0]> : tensor<3xi64>, strides = dense<1> : tensor<3xi64>}> : (tensor<4x3x6xf32>) -> tensor<4x1x6xf32>
  // CHECK: %[[RES3:.*]] = mhlo.reshape %[[SLICE3]] : (tensor<4x1x6xf32>) -> tensor<4x6xf32>

			}
		} else {
			if rhs == nil {
				r = s.zeroVal(t)
			} else {
				r = s.expr(rhs)
			}
		}

		var skip skipMask
		if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
			// We're assigning a slicing operation back to its source.
			// Don't write back fields we aren't changing. See issue #14855.

		{"SliceExpr", Type, 0},
		{"SliceExpr.High", Field, 0},
		{"SliceExpr.Lbrack", Field, 0},
		{"SliceExpr.Low", Field, 0},
		{"SliceExpr.Max", Field, 2},
		{"SliceExpr.Rbrack", Field, 0},
		{"SliceExpr.Slice3", Field, 2},
		{"SliceExpr.X", Field, 0},
		{"SortImports", Func, 0},
		{"Spec", Type, 0},
		{"StarExpr", Type, 0},
		{"StarExpr.Star", Field, 0},
		{"StarExpr.X", Field, 0},
		{"Stmt", Type, 0},