In Vivado Design Suite 2013.4, the core may issue a critical warning similar to the following during implementation:
CRITICAL WARNING: [Netlist 29-98] The DSP48E2 multiplier has increased from 25x18 to 27x18, so automatic retargeting when USE_MULT=DYNAMIC is not guaranteed. Please review instance 'U0/i_synth/i_synth/g_ant.g_op.f1_op/filt/g_filt.fc/mac.mac/fir_select/gen_polyphase_interpolation_symmetry.fir/gen_accum.gen_paths.accumulator/gen_structural.gen_virte.gen_dsp48e.gen_dsp48e1_v6.dsp48e1_v6' and make appropriate modifications to ensure pins A[26:25] are sign-extension of A during multiply operation.
This critical warning can be safely ignored as the circuit will operate as desired.
This issue is planned to be fixed in 2014.1.
For a detailed list of LogiCORE IP DUC/DDC Compiler Release Notes and Known Issues, see (Xilinx Answer 54476).