[PATCH] D54388: [llvm-exegesis] InstructionBenchmarkClustering::rangeQuery(): use llvm::SmallVector<size_t, 0> for storage.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


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Comment at: tools/llvm-exegesis/lib/Clustering.cpp:38
 InstructionBenchmarkClustering::rangeQuery(const size_t Q) const {
-  std::vector<size_t> Neighbors;
+  llvm::SmallVector<size_t, 0> Neighbors;
   const auto &QMeasurements = Points_[Q].Measurements;
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MaskRay wrote:
> The size of `Neighbors` is bound by the number of points. The vector can be reserved before the loop calling `rangeQuery` and passed as a parameter into `rangeQuery`.
Good point.

That is the **upper** bound, not in all cases that will be actual size of the vector.
Given that you have accepted D54390, such optimization can be safely made
but only *after* D54390 (and it can be replaced by a `std::vector`),
but i really really don't want to change/reorder patches,
because that would require to re-do all of the benchmarks/measurements.

So i will add a new patch with that fix.


Repository:
  rL LLVM

https://reviews.llvm.org/D54388