[llvm-exegesis] InstructionBenchmarkClustering::rangeQuery(): use llvm::SmallVector<size_t, 0> for storage.
Summary:
Old: (D54383)
```
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):
9098.781978 task-clock (msec) # 1.000 CPUs utilized ( +- 0.16% )
...
9.1015 +- 0.0148 seconds time elapsed ( +- 0.16% )
```
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):
8553.352480 task-clock (msec) # 1.000 CPUs utilized ( +- 0.12% )
...
8.5539 +- 0.0105 seconds time elapsed ( +- 0.12% )
```
So another -6%.
That is because the `SmallVector` **doubles** it size when reallocating, which is great here,
since we can't `reserve()` since we can't know how many `Neighbors` we will have.
Reviewers: courbet, MaskRay, RKSimon, gchatelet, john.brawn
Subscribers: tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D54388
llvm-svn: 347200