Parallelization of IIR filters using SIMD extensions

The SIMD parallelization of HR or recursive filters is more difficult than that of FIR filters due to additional data dependencies. While other methods concentrate on appropriate scheduling to enable SIMD parallel execution, this paper proposes a new method where data dependencies are resolved by fusing the recursive application of filter taps into single coefficients. In this way the overhead over perfect parallelity can be reduced to one vector multiply-accumulate operation. Speedups from 1.5 to 4.5 can be obtained with the 4-way SIMD Intel SSE extension, depending on the number of filter taps.