switch n.X.Op() {
	case ir.OCALLMETH:
		base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
	case ir.OCALLFUNC, ir.OCALLINTER:
		return n
	}

	if n.X.Op() == ir.ODOTPTR && ir.IsReflectHeaderDataField(n.X) {
		return n
	}

	// Find original unsafe.Pointer operands involved in this
	// arithmetic expression.
	//
	// "It is valid both to add and to subtract offsets from a

		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
	}

	// Left is not ssa-able. Compute its address.
	addr := s.addr(left)
	if ir.IsReflectHeaderDataField(left) {
		// Package unsafe's documentation says storing pointers into
		// reflect.SliceHeader and reflect.StringHeader's Data fields
		// is valid, even though they have type uintptr (#19168).