Unmet Latency Constraint - 2020.2 English

Vitis HLS Messaging (UG1448)

Document ID
UG1448
Release Date
2020-11-24
Version
2020.2 English

Description

The tool is informing the user that the user-specified latency constraint is being ignoerd.

Explanation

The tool is informing the user that the LATENCY pragma specified is un-realistic with the code and it will ignoring this latency pragma.

This behavior can be seen in the below code,i.e; the floating-point add: A +5 takes more than a cycle and it is impossible to meet this constraint.

void example_label(float A[50], int B[50]) {
  int i;
  int C[50];
 LOOP_1: for(i = 0; i < 50; i++){
#pragma HLS LATENCY max=1
        C[i] = A[i] + 5;
  }
...
}

Solution

Relax the user latency constraint as per the code.