[llvm-exegesis] Sum counter values when several counters are specified for a ProcRes.

[courbet]

Summary

This allows handling memory ports on SNB.

tools/llvm-exegesis/lib/Uops.cpp

UopsBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
 
   std::vector<BenchmarkMeasure> Result;
   for (unsigned ProcResIdx = 1;
        ProcResIdx < SchedModel.getNumProcResourceKinds(); ++ProcResIdx) {
     const char *const PfmCounters = SchedModel.getExtraProcessorInfo()
                                         .PfmCounters.IssueCounters[ProcResIdx];
     if (!PfmCounters)
       continue;
-    // FIXME: Sum results when there are several counters for a single ProcRes
+    // We sum counts when there are several counters for a single ProcRes
     // (e.g. P23 on SandyBridge).
-    pfm::PerfEvent UopPerfEvent(PfmCounters);
+    int64_t CounterValue = 0;
+    llvm::SmallVector<llvm::StringRef, 2> CounterNames;
+    llvm::StringRef(PfmCounters).split(CounterNames, ',');
+    for (const auto& CounterName : CounterNames) {
+      pfm::PerfEvent UopPerfEvent(CounterName);
       if (!UopPerfEvent.valid())
         llvm::report_fatal_error(
             llvm::Twine("invalid perf event ").concat(PfmCounters));
       pfm::Counter Counter(UopPerfEvent);
       Counter.start();
       Function();
       Counter.stop();
+      CounterValue += Counter.read();
+    }
     Result.push_back({llvm::itostr(ProcResIdx),
-                      static_cast<double>(Counter.read()) / NumRepetitions,
+                      static_cast<double>(CounterValue) / NumRepetitions,
                       SchedModel.getProcResource(ProcResIdx)->Name});
   }
   return Result;
 }
 
 } // namespace exegesis