fix(bench): prevent compiler from hoisting fibonacci call out of loop

not-matthias · not-matthias · commit 9816e99b015f · 2026-05-22T15:25:40.000+02:00
diff --git a/examples/google_benchmark_cmake/fibonacci_bench.hpp b/examples/google_benchmark_cmake/fibonacci_bench.hpp
@@ -20,6 +20,7 @@ BENCHMARK(BM_FibonacciRecursive)->Arg(35)->MinTime(5);
 static void BM_FibonacciRecursive_Darwin(benchmark::State& state) {
   int n = static_cast<int>(state.range(0));
   for (auto _ : state) {
+    benchmark::DoNotOptimize(n);
     uint64_t result = fibonacci_recursive(n);
     benchmark::DoNotOptimize(result);
   }

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,7 @@ BENCHMARK(BM_FibonacciRecursive)->Arg(35)->MinTime(5);`
`20`	`20`	`static void BM_FibonacciRecursive_Darwin(benchmark::State& state) {`
`21`	`21`	`int n = static_cast<int>(state.range(0));`
`22`	`22`	`for (auto _ : state) {`
	`23`	`+ benchmark::DoNotOptimize(n);`
`23`	`24`	`uint64_t result = fibonacci_recursive(n);`
`24`	`25`	`benchmark::DoNotOptimize(result);`
`25`	`26`	`}`