You have to give Intel/AMD a lot of credit for improving the performance of existing binaries. They've reduced CPI and improved ILP a lot in 16 years, not to me

You have to give Intel/AMD a lot of credit for improving the performance of existing binaries. They've reduced CPI and improved ILP a lot in 16 years, not to mention vastly improved various forms of prediction, caching and speculation. A lot of the performance improvement gleaned from modern compilers will be better reduction of the C++ language itself, e.g. smarter inlining, LTO, devirtualisation etc.