- don't generate "&& true" when generating instruction eq() fn;
- use more Self;
- use subsec_millis instead of subsec_nanos and divide;
- coalesce two ifs;
* Use FxHashMap instead of HashMap for better performance
* Replace the binary search in the coalescing pass with a FxHashMap
This speeds up coalescing by up to 16% and overall compilation by 9%