There is ongoing work to improve debuggability for optimized code. https://discourse.llvm.org/t/rfc-redefine-og-o1-and-add-a-ne...
``` Mode | Execution Time | Debuggability | Compile Time O0 | 1.0000 | 1.0000 | 1.0000 Og | 0.3439 | 0.5357 | 1.8630 O1 | 0.3082 | 0.4241 | 1.7880 O2g | 0.2823 | 0.4845 | 3.0420 O2 | 0.2514 | 0.3908 | 2.9380 ```