Function Pipelining - 2022.2 English

Vitis High-Level Synthesis User Guide (UG1399)

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2022.2 English

Function pipelining is handled similarly to loop pipelining as described in Pipelining Loops. Vitis HLS treats the function body as if it were the same as a loop body being called multiple times - except in this case, it is the function that is called multiple times and the tools pipelines the execution of these calls. So similar to loops, when a function is pipelined, all the loops in the function body and in the hierarchy below are automatically unrolled. This is a requirement for pipelining to proceed. If a loop has variable bounds and it cannot be unrolled then this will prevent the function from being pipelined.