[PATCH] D48779: [llvm-exegesis] Delegate the decision of cycle counter name to the target

[John Brawn via Phabricator via llvm-commits]

john.brawn created this revision.
john.brawn added reviewers: courbet, gchatelet.
Herald added a subscriber: tschuett.

Currently the cycle counter is taken from the subtarget schedule model, which isn't any use if the subtarget doesn't have one. Delegate the decision to the target benchmark runner, as it may know better what to do in that case, with the default being the current behaviour.


Repository:
  rL LLVM

https://reviews.llvm.org/D48779

Files:
  tools/llvm-exegesis/lib/Latency.cpp
  tools/llvm-exegesis/lib/Latency.h
  tools/llvm-exegesis/llvm-exegesis.cpp


Index: tools/llvm-exegesis/llvm-exegesis.cpp
===================================================================
--- tools/llvm-exegesis/llvm-exegesis.cpp
+++ tools/llvm-exegesis/llvm-exegesis.cpp
@@ -140,10 +140,6 @@
     return;
   }
 
-  // FIXME: Do not require SchedModel for latency.
-  if (!State.getSubtargetInfo().getSchedModel().hasExtraProcessorInfo())
-    llvm::report_fatal_error("sched model is missing extra processor info!");
-
   const std::unique_ptr<BenchmarkRunner> Runner =
       State.getExegesisTarget().createBenchmarkRunner(BenchmarkMode, State);
   if (!Runner) {
Index: tools/llvm-exegesis/lib/Latency.h
===================================================================
--- tools/llvm-exegesis/lib/Latency.h
+++ tools/llvm-exegesis/lib/Latency.h
@@ -38,6 +38,8 @@
   std::vector<BenchmarkMeasure>
   runMeasurements(const ExecutableFunction &EF,
                   const unsigned NumRepetitions) const override;
+
+  virtual const char *getCounterName() const;
 };
 
 } // namespace exegesis
Index: tools/llvm-exegesis/lib/Latency.cpp
===================================================================
--- tools/llvm-exegesis/lib/Latency.cpp
+++ tools/llvm-exegesis/lib/Latency.cpp
@@ -94,19 +94,27 @@
   return generateTwoInstructionPrototype(Instr);
 }
 
+const char *LatencyBenchmarkRunner::getCounterName() const {
+  // FIXME: Do not require SchedModel for latency.
+  if (!State.getSubtargetInfo().getSchedModel().hasExtraProcessorInfo())
+    llvm::report_fatal_error("sched model is missing extra processor info!");
+  const char *CounterName = State.getSubtargetInfo()
+                                .getSchedModel()
+                                .getExtraProcessorInfo()
+                                .PfmCounters.CycleCounter;
+  if (!CounterName)
+    llvm::report_fatal_error("sched model does not define a cycle counter");
+  return CounterName;
+}
+
 std::vector<BenchmarkMeasure>
 LatencyBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
                                         const unsigned NumRepetitions) const {
   // Cycle measurements include some overhead from the kernel. Repeat the
   // measure several times and take the minimum value.
   constexpr const int NumMeasurements = 30;
   int64_t MinLatency = std::numeric_limits<int64_t>::max();
-  const char *CounterName = State.getSubtargetInfo()
-                                .getSchedModel()
-                                .getExtraProcessorInfo()
-                                .PfmCounters.CycleCounter;
-  if (!CounterName)
-    llvm::report_fatal_error("sched model does not define a cycle counter");
+  const char *CounterName = getCounterName();
   const pfm::PerfEvent CyclesPerfEvent(CounterName);
   if (!CyclesPerfEvent.valid())
     llvm::report_fatal_error("invalid perf event");


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