Optimizations that are enabled by default are considered safe -- they have been well tested and shown to not cause any problems. Opzimizations that are disabled by default have not been as well tested. Using them might be unsafe. Before reporting any problems with the compiler, please make sure to retest with only the default optimizations and let me know the outcome.
-[no-]cexpr-reductionenable/disable constant expression reduction
Purpose: Detect expressions or subexpressions composed completely of constants, and reduce these to a single value.