[llvm-exegesis] Output the unscaled value as well as the scaled one.

Summary: See PR38936 for context.

Reviewers: gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D52500

llvm-svn: 343081

11 files changed, 45 insertions, 31 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/Analysis.cpp b/llvm/tools/llvm-exegesis/lib/Analysis.cpp
index bb51180..54dc4be 100644
--- a/llvm/tools/llvm-exegesis/lib/Analysis.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Analysis.cpp
@@ -139,7 +139,7 @@ void Analysis::printInstructionRowCsv(const size_t PointId,
 #endif
   for (const auto &Measurement : Point.Measurements) {
     OS << kCsvSep;
-    writeMeasurementValue<kEscapeCsv>(OS, Measurement.Value);
+    writeMeasurementValue<kEscapeCsv>(OS, Measurement.PerInstructionValue);
   }
   OS << "\n";
 }
@@ -410,14 +410,14 @@ bool Analysis::SchedClassCluster::measurementsMatch(
       return false;
     }
     // Find the latency.
-    SchedClassPoint[0].Value = 0.0;
+    SchedClassPoint[0].PerInstructionValue = 0.0;
     for (unsigned I = 0; I < SC.SCDesc->NumWriteLatencyEntries; ++I) {
       const llvm::MCWriteLatencyEntry *const WLE =
           STI.getWriteLatencyEntry(SC.SCDesc, I);
-      SchedClassPoint[0].Value =
-          std::max<double>(SchedClassPoint[0].Value, WLE->Cycles);
+      SchedClassPoint[0].PerInstructionValue =
+          std::max<double>(SchedClassPoint[0].PerInstructionValue, WLE->Cycles);
     }
-    ClusterCenterPoint[0].Value = Representative[0].avg();
+    ClusterCenterPoint[0].PerInstructionValue = Representative[0].avg();
   } else if (Mode == InstructionBenchmark::Uops) {
     for (int I = 0, E = Representative.size(); I < E; ++I) {
       // Find the pressure on ProcResIdx `Key`.
@@ -433,11 +433,11 @@ bool Analysis::SchedClassCluster::measurementsMatch(
                        [ProcResIdx](const std::pair<uint16_t, float> &WPR) {
                          return WPR.first == ProcResIdx;
                        });
-      SchedClassPoint[I].Value =
+      SchedClassPoint[I].PerInstructionValue =
           ProcResPressureIt == SC.IdealizedProcResPressure.end()
               ? 0.0
               : ProcResPressureIt->second;
-      ClusterCenterPoint[I].Value = Representative[I].avg();
+      ClusterCenterPoint[I].PerInstructionValue = Representative[I].avg();
     }
   } else {
     llvm::errs() << "unimplemented measurement matching for mode " << Mode
diff --git a/llvm/tools/llvm-exegesis/lib/Analysis.h b/llvm/tools/llvm-exegesis/lib/Analysis.h
index 3c33caf..1e6294b 100644
--- a/llvm/tools/llvm-exegesis/lib/Analysis.h
+++ b/llvm/tools/llvm-exegesis/lib/Analysis.h
@@ -69,7 +69,7 @@ private:
     const std::vector<size_t> &getPointIds() const { return PointIds; }
 
     // Return the cluster centroid.
-    const std::vector<BenchmarkMeasureStats> &getRepresentative() const {
+    const std::vector<PerInstructionStats> &getRepresentative() const {
       return Representative;
     }
 
@@ -85,7 +85,7 @@ private:
     InstructionBenchmarkClustering::ClusterId ClusterId;
     std::vector<size_t> PointIds;
     // Measurement stats for the points in the SchedClassCluster.
-    std::vector<BenchmarkMeasureStats> Representative;
+    std::vector<PerInstructionStats> Representative;
   };
 
   void printInstructionRowCsv(size_t PointId, llvm::raw_ostream &OS) const;
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
index 9a41114..1748c53 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
@@ -164,9 +164,10 @@ template <> struct SequenceElementTraits<exegesis::BenchmarkMeasure> {
 // e.g. { "key": "the key", "value": 0123 }
 template <> struct MappingTraits<exegesis::BenchmarkMeasure> {
   static void mapping(IO &Io, exegesis::BenchmarkMeasure &Obj) {
-    Io.mapRequired("key", Obj.Key);
-    Io.mapRequired("value", Obj.Value);
     Io.mapOptional("debug_string", Obj.DebugString);
+    Io.mapRequired("value", Obj.PerInstructionValue);
+    Io.mapOptional("per_snippet_value", Obj.PerSnippetValue);
+    Io.mapRequired("key", Obj.Key);
   }
   static const bool flow = true;
 };
@@ -345,14 +346,14 @@ llvm::Error InstructionBenchmark::writeYaml(const LLVMState &State,
   return llvm::Error::success();
 }
 
-void BenchmarkMeasureStats::push(const BenchmarkMeasure &BM) {
+void PerInstructionStats::push(const BenchmarkMeasure &BM) {
   if (Key.empty())
     Key = BM.Key;
   assert(Key == BM.Key);
   ++NumValues;
-  SumValues += BM.Value;
-  MaxValue = std::max(MaxValue, BM.Value);
-  MinValue = std::min(MinValue, BM.Value);
+  SumValues += BM.PerInstructionValue;
+  MaxValue = std::max(MaxValue, BM.PerInstructionValue);
+  MinValue = std::min(MinValue, BM.PerInstructionValue);
 }
 
 } // namespace exegesis
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.h b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.h
index 62653cd..e4e29ef 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.h
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.h
@@ -42,7 +42,12 @@ struct InstructionBenchmarkKey {
 
 struct BenchmarkMeasure {
   std::string Key;
-  double Value;
+  // This is the per-instruction value, i.e. measured quantity scaled per
+  // instruction.
+  double PerInstructionValue;
+  // This is the per-snippet value, i.e. measured quantity for one repetition of
+  // the whole snippet.
+  double PerSnippetValue;
   std::string DebugString;
 };
 
@@ -81,7 +86,7 @@ struct InstructionBenchmark {
 // Utilities to work with Benchmark measures.
 
 // A class that measures stats over benchmark measures.
-class BenchmarkMeasureStats {
+class PerInstructionStats {
 public:
   void push(const BenchmarkMeasure &BM);
 
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index efda689..7addb0a 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -88,7 +88,15 @@ BenchmarkRunner::runConfiguration(const BenchmarkCode &BC,
                << *ObjectFilePath << "\n";
   const ExecutableFunction EF(State.createTargetMachine(),
                               getObjectFromFile(*ObjectFilePath));
-  InstrBenchmark.Measurements = runMeasurements(EF, *Scratch, NumRepetitions);
+  InstrBenchmark.Measurements = runMeasurements(EF, *Scratch);
+  assert(InstrBenchmark.NumRepetitions > 0 && "invalid NumRepetitions");
+  for (BenchmarkMeasure &BM : InstrBenchmark.Measurements) {
+    // Scale the measurements by instruction.
+    BM.PerInstructionValue /= InstrBenchmark.NumRepetitions;
+    // Scale the measurements by snippet.
+    BM.PerSnippetValue *= static_cast<double>(BC.Instructions.size()) /
+                   InstrBenchmark.NumRepetitions;
+  }
 
   return InstrBenchmark;
 }
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
index 07ab23c..e5b567f 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
@@ -69,8 +69,8 @@ protected:
 
 private:
   virtual std::vector<BenchmarkMeasure>
-  runMeasurements(const ExecutableFunction &EF, ScratchSpace &Scratch,
-                  const unsigned NumRepetitions) const = 0;
+  runMeasurements(const ExecutableFunction &EF,
+                  ScratchSpace &Scratch) const = 0;
 
   llvm::Expected<std::string>
   writeObjectFile(const BenchmarkCode &Configuration,
diff --git a/llvm/tools/llvm-exegesis/lib/Clustering.cpp b/llvm/tools/llvm-exegesis/lib/Clustering.cpp
index a966c72..b63afec 100644
--- a/llvm/tools/llvm-exegesis/lib/Clustering.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Clustering.cpp
@@ -53,7 +53,7 @@ bool InstructionBenchmarkClustering::isNeighbour(
     const std::vector<BenchmarkMeasure> &Q) const {
   double DistanceSquared = 0.0;
   for (size_t I = 0, E = P.size(); I < E; ++I) {
-    const auto Diff = P[I].Value - Q[I].Value;
+    const auto Diff = P[I].PerInstructionValue - Q[I].PerInstructionValue;
     DistanceSquared += Diff * Diff;
   }
   return DistanceSquared <= EpsilonSquared_;
diff --git a/llvm/tools/llvm-exegesis/lib/Latency.cpp b/llvm/tools/llvm-exegesis/lib/Latency.cpp
index d09cdc5..3c402c4 100644
--- a/llvm/tools/llvm-exegesis/lib/Latency.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Latency.cpp
@@ -109,8 +109,7 @@ LatencyBenchmarkRunner::~LatencyBenchmarkRunner() = default;
 
 std::vector<BenchmarkMeasure>
 LatencyBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
-                                        ScratchSpace &Scratch,
-                                        const unsigned NumRepetitions) const {
+                                        ScratchSpace &Scratch) const {
   // Cycle measurements include some overhead from the kernel. Repeat the
   // measure several times and take the minimum value.
   constexpr const int NumMeasurements = 30;
@@ -131,7 +130,8 @@ LatencyBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
     if (Value < MinLatency)
       MinLatency = Value;
   }
-  return {{"latency", static_cast<double>(MinLatency) / NumRepetitions, ""}};
+  return {{"latency", static_cast<double>(MinLatency),
+           static_cast<double>(MinLatency), ""}};
 }
 
 } // namespace exegesis
diff --git a/llvm/tools/llvm-exegesis/lib/Latency.h b/llvm/tools/llvm-exegesis/lib/Latency.h
index 5b9be00..3a72d02 100644
--- a/llvm/tools/llvm-exegesis/lib/Latency.h
+++ b/llvm/tools/llvm-exegesis/lib/Latency.h
@@ -44,8 +44,8 @@ public:
 
 private:
   std::vector<BenchmarkMeasure>
-  runMeasurements(const ExecutableFunction &EF, ScratchSpace &Scratch,
-                  const unsigned NumRepetitions) const override;
+  runMeasurements(const ExecutableFunction &EF,
+                  ScratchSpace &Scratch) const override;
 
   virtual const char *getCounterName() const;
 };
diff --git a/llvm/tools/llvm-exegesis/lib/Uops.cpp b/llvm/tools/llvm-exegesis/lib/Uops.cpp
index beb9fa8..dbecbfe 100644
--- a/llvm/tools/llvm-exegesis/lib/Uops.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Uops.cpp
@@ -252,8 +252,7 @@ UopsSnippetGenerator::generateCodeTemplate(unsigned Opcode) const {
 
 std::vector<BenchmarkMeasure>
 UopsBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
-                                     ScratchSpace &Scratch,
-                                     const unsigned NumRepetitions) const {
+                                     ScratchSpace &Scratch) const {
   const auto &SchedModel = State.getSubtargetInfo().getSchedModel();
 
   std::vector<BenchmarkMeasure> Result;
@@ -281,7 +280,8 @@ UopsBenchmarkRunner::runMeasurements(const ExecutableFunction &Function,
       CounterValue += Counter.read();
     }
     Result.push_back({llvm::itostr(ProcResIdx),
-                      static_cast<double>(CounterValue) / NumRepetitions,
+                      static_cast<double>(CounterValue),
+                      static_cast<double>(CounterValue),
                       SchedModel.getProcResource(ProcResIdx)->Name});
   }
   return Result;
diff --git a/llvm/tools/llvm-exegesis/lib/Uops.h b/llvm/tools/llvm-exegesis/lib/Uops.h
index 160397a..aff583b 100644
--- a/llvm/tools/llvm-exegesis/lib/Uops.h
+++ b/llvm/tools/llvm-exegesis/lib/Uops.h
@@ -71,8 +71,8 @@ public:
 
 private:
   std::vector<BenchmarkMeasure>
-  runMeasurements(const ExecutableFunction &EF, ScratchSpace &Scratch,
-                  const unsigned NumRepetitions) const override;
+  runMeasurements(const ExecutableFunction &EF,
+                  ScratchSpace &Scratch) const override;
 };
 
 } // namespace exegesis