What is the difference between the report generated by clang’s -fsave-optimization-record flag and opt’s -analyze flag?
The opt flag does prevent opt from printing/saving the resulting IR. opt
will instead asks the passes to "print" a summary of what they did.
The clang flag enables and saves remarks
(https://clang.llvm.org/docs/UsersManual.html#options-to-emit-optimization-reports)
Remarks are printed by some passes while they perform their actions.