Fixes #357: broken RMS values when time unit is set. (#362)

src/complexity.cc

@@ -295,6 +295,11 @@ std::vector<BenchmarkReporter::Run> ComputeBigO(
   big_o.report_big_o = true;
   big_o.complexity = result_cpu.complexity;
 
+  // All the time results are reported after being multiplied by the
+  // time unit multiplier. But since RMS is a relative quantity it
+  // should not be multiplied at all. So, here, we _divide_ it by the
+  // multiplier so that when it is multiplied later the result is the
+  // correct one.
   double multiplier = GetTimeUnitMultiplier(reports[0].time_unit);
 
   // Only add label to mean/stddev if it is same for all runs
@@ -307,6 +312,9 @@ std::vector<BenchmarkReporter::Run> ComputeBigO(
   rms.cpu_accumulated_time = result_cpu.rms / multiplier;
   rms.report_rms = true;
   rms.complexity = result_cpu.complexity;
+  // don't forget to keep the time unit, or we won't be able to
+  // recover the correct value.
+  rms.time_unit = reports[0].time_unit;
 
   results.push_back(big_o);
   results.push_back(rms);