Dead-code elimination silently zeroing out an unused benchmark result is a real bug class, one Chandler Carruth's CppCon benchmarking talks are built almost entirely around, which is exactly why Google Benchmark ships DoNotOptimize() and Rust ships std::hint::black_box. Teams have shipped 'optimizations' validated by a benchmark that GCC had already deleted at -O2, learning the fix only after the change made no real-world difference.