7.2.9. Summary of Performance Gains from Verilator Warnings

Table 7.1 shows the performance gains which can be achieved by fixing the various Verilator warnings and language inconsistencies.

Run Description	Build Time	Run Time	Performance
Baseline	13.94 s	27.67 s	42.66 kHz
`CASEX` fixed	13.91 s	27.59 s	42.76 kHz
`VARHIDDEN` fixed	13.91 s	27.66 s	42.66 kHz
`IMPLICIT` fixed	13.89 s	27.77 s	42.50 kHz
`WIDTH` fixed	13.92 s	27.41 s	43.04 kHz
`CASEINCOMPLETE` fixed	13.93 s	27.24 s	43.31 kHz
`COMBDLY` fixed	13.92 s	27.32 s	43.20 kHz
`UNOPTFLAT` fixed	13.95 s	25.07 s	47.06 kHz
SystemVerilog compliant	13.91 s	24.85 s	47.49 kHz

Table 7.1. Comparison of model performance when fixing Verilator warnings.

The table confirms that the majority of warnings do not greatly affect performance. They are primarily about writing good quality RTL. However fixing UNOPTFLAT gave a significant performance improvement.