Vitis HLS will now infer a shift register when encountering the following code:
int A[N]; // This will be replaced by a shift register
for(...) {
// The loop below is the shift operation
for (int i = 0; i < N-1; ++i)
A[i] = A[i+1];
A[N] = ...;
// This is an access to the shift register
... A[x] ...
}
Shift registers can perform a shift/cycle, which offers a significant performance improvement, and also allows a random read access per cycle anywhere in the shift register, thus it is more flexible than a FIFO.