## 4 Evaluation Results
### Experimental Results  
The experiments are conducted by external evolution on a PC with a 4-core processor of 11 th Gen Intel(R) Core(TM) i5-1130G7 with 1.1 GHz and 8 GB of memory. Since the scale of the experimental circuit is small, the population size is set to 100, and the corresponding iterations are set for circuit-I and circuit-II, respectively 2000 and 20,000 iterations. We count the time required to achieve EA in different ERs to evaluate the impact of ER on evolutionary efficiency. Meanwhile, the evolution success rate (ESR) is also proposed as a metric to assess the impact of the insertion of different numbers of HTs in CGRAs on evolution. The ESR is defined as: the number of successful evolutions/the total number of evolutions \(\times\) 100%, and the total number of evolutions is set to 10 in this paper. The corresponding number of iterations are evolved for circuit-I and circuit-II, where the optimal evolution results are shown in Figure 9.  
Tables 1 and 2 show the time required to implement EA in different ERs for circuit-I and circuit-II. Circuit-I requires four PEs to implement EA in all evolvable region (AER, 9 PE) and in the optimized evolvable region (OER, 6 PE), respectively, and it can be seen that the evolution time required in the OER is less than the AER. The increase in evolution efficiency is not very significant, mainly due to the simpler implementation of circuit-I and the small of AERs. Circuit-II requires eight PEs to implement EA in the AER (25 PE) and in the OER (20 PE, 16 PE, 15 PE, 12 PE, 10 PE), respectively. It is clear from Table 2 that the evolution efficiency increases sharply as the ER is reduced. The above experiments fully illustrate that shrinking ER can help improve the evolution efficiency. The reason is that optimizing ER can reduce the search space to accelerate the evolution of individuals toward the optimal solution. In particular, when the ER is similar to the circuit size, only a few of the generated initial individuals satisfy the solution conditions and it is not easy to expand the search range, so the convergence is accelerated in the subsequent iterations. Figure 8: Description of the example circuit-II and anticipation of the HT mitigation mechanism. (**a**) original circuit-II. (**b**) HT inserted in the circuit-II. (**c**) EA-based reconfiguration to correct the circuit-II. (Red mark: the HT-I PEs; Blue Arrow: The data flow). Figure 10 shows the effect of the insertion of different numbers of HTs in the CGRA on the ESR. Circuit-I requires four PEs to achieve the function and it evolves on a CGRA with nine PEs. In Figure 9a, it can be seen that circuit-I evolves successfully as long as there are more than four available PEs in the CGRA. Circuit-II requires eight PEs to achieve functionality and it evolves on a CGRA with 25 PEs. The range of the number of insertion HTs at this point is 1-25. Since the ESR is 100% for all insertions less than 10 and 0 for all insertions greater than 20, only this representative part is shown in Figure 9b to illustrate the variety of ESR with the number of insertion HTs. When the number of insertion HTs reaches 15, there are only 10 PEs available in CGRA. At this time, the ESR cannot reach 100%. When the number of insertion HTs reaches 16,17, it is more difficult to find a qualified circuit structure among the available PEs, so the ESR drops significantly. The reason for this is that circuit-II requires eight PEs to achieve the function, and the circuit combinations are more diverse, making it difficult to obtain a feasible solution in the limited number of PEs. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline
**HR Times** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **Avg.** \\ \hline
9 & 0.620 & 0.609 & 0.634 & 0.679 & 0.653 & 0.638 & 0.625 & 0.607 & 0.595 & 0.681 & 0.634 \\
6 & 0.595 & 0.643 & 0.65 & 0.606 & 0.63 & 0.646 & 0.625 & 0.618 & 0.666 & 0.631 & 0.631 \\ \hline \end{tabular}
\end{table} 
Table 1: Evolution time of circuit-I in different evolvable regions.