[llvm-exegesis] Move InstructionBenchmarkClustering::isNeighbour() into header

Summary:
Old: (D54390)
```
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=100000 -benchmarks-file=/tmp/benchmarks.yaml -analysis-inconsistencies-output-file=/tmp/clusters.html' (10 runs):

       7432.421721      task-clock (msec)         #    1.000 CPUs utilized            ( +-  0.15% )
...
            7.4336 +- 0.0115 seconds time elapsed  ( +-  0.15% )
```
New:
```
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=100000 -benchmarks-file=/tmp/benchmarks.yaml -analysis-inconsistencies-output-file=/tmp/clusters.html' (10 runs):

       6569.936144      task-clock (msec)         #    1.000 CPUs utilized            ( +-  0.22% )
...
            6.5711 +- 0.0143 seconds time elapsed  ( +-  0.22% )
```
And another -12%. You'd think it would be `inline`d anyway, but no! :)

Reviewers: courbet, MaskRay, RKSimon, gchatelet, john.brawn

Reviewed By: courbet, MaskRay

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D54393

llvm-svn: 347203

2 files changed, 8 insertions, 12 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/Clustering.cpp b/llvm/tools/llvm-exegesis/lib/Clustering.cpp
index df45de31990..360966a9478 100644
--- a/llvm/tools/llvm-exegesis/lib/Clustering.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Clustering.cpp
@@ -49,17 +49,6 @@ void InstructionBenchmarkClustering::rangeQuery(
   }
 }
 
-bool InstructionBenchmarkClustering::isNeighbour(
-    const std::vector<BenchmarkMeasure> &P,
-    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].PerInstructionValue - Q[I].PerInstructionValue;
-    DistanceSquared += Diff * Diff;
-  }
-  return DistanceSquared <= EpsilonSquared_;
-}
-
 InstructionBenchmarkClustering::InstructionBenchmarkClustering(
     const std::vector<InstructionBenchmark> &Points,
     const double EpsilonSquared)
diff --git a/llvm/tools/llvm-exegesis/lib/Clustering.h b/llvm/tools/llvm-exegesis/lib/Clustering.h
index e746e4ba41d..297651c85e9 100644
--- a/llvm/tools/llvm-exegesis/lib/Clustering.h
+++ b/llvm/tools/llvm-exegesis/lib/Clustering.h
@@ -90,7 +90,14 @@ public:
 
   // Returns true if the given point is within a distance Epsilon of each other.
   bool isNeighbour(const std::vector<BenchmarkMeasure> &P,
-                   const std::vector<BenchmarkMeasure> &Q) const;
+                   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].PerInstructionValue - Q[I].PerInstructionValue;
+      DistanceSquared += Diff * Diff;
+    }
+    return DistanceSquared <= EpsilonSquared_;
+  }
 
 private:
   InstructionBenchmarkClustering(