[libc++] Add test coverage for unordered containers comparison (#66692)

This patch is a melting pot of changes picked up from
https://llvm.org/D61878. It adds a few tests checking corner cases of
unordered containers comparison and adds benchmarks for a few
unordered_set operations.

2 files changed, 50 insertions, 0 deletions

diff --git a/libcxx/benchmarks/ContainerBenchmarks.h b/libcxx/benchmarks/ContainerBenchmarks.h
index 5ab6f61..071e46c 100644
--- a/libcxx/benchmarks/ContainerBenchmarks.h
+++ b/libcxx/benchmarks/ContainerBenchmarks.h
@@ -179,6 +179,37 @@ static void BM_Rehash(benchmark::State& st, Container c, GenInputs gen) {
   }
 }
 
+template <class Container, class GenInputs>
+static void BM_Compare_same_container(benchmark::State& st, Container, GenInputs gen) {
+  auto in = gen(st.range(0));
+  Container c1(in.begin(), in.end());
+  Container c2 = c1;
+
+  benchmark::DoNotOptimize(&(*c1.begin()));
+  benchmark::DoNotOptimize(&(*c2.begin()));
+  while (st.KeepRunning()) {
+    bool res = c1 == c2;
+    benchmark::DoNotOptimize(&res);
+    benchmark::ClobberMemory();
+  }
+}
+
+template <class Container, class GenInputs>
+static void BM_Compare_different_containers(benchmark::State& st, Container, GenInputs gen) {
+  auto in1 = gen(st.range(0));
+  auto in2 = gen(st.range(0));
+  Container c1(in1.begin(), in1.end());
+  Container c2(in2.begin(), in2.end());
+
+  benchmark::DoNotOptimize(&(*c1.begin()));
+  benchmark::DoNotOptimize(&(*c2.begin()));
+  while (st.KeepRunning()) {
+    bool res = c1 == c2;
+    benchmark::DoNotOptimize(&res);
+    benchmark::ClobberMemory();
+  }
+}
+
 } // end namespace ContainerBenchmarks
 
 #endif // BENCHMARK_CONTAINER_BENCHMARKS_H
diff --git a/libcxx/benchmarks/unordered_set_operations.bench.cpp b/libcxx/benchmarks/unordered_set_operations.bench.cpp
index 96aa2e0..d49de57 100644
--- a/libcxx/benchmarks/unordered_set_operations.bench.cpp
+++ b/libcxx/benchmarks/unordered_set_operations.bench.cpp
@@ -290,6 +290,25 @@ BENCHMARK_CAPTURE(BM_Rehash,
 BENCHMARK_CAPTURE(BM_Rehash, unordered_set_int_arg, std::unordered_set<int>{}, getRandomIntegerInputs<int>)
     ->Arg(TestNumInputs);
 
+//----------------------------------------------------------------------------//
+//                         BM_Compare
+// ---------------------------------------------------------------------------//
+
+BENCHMARK_CAPTURE(
+    BM_Compare_same_container, unordered_set_string, std::unordered_set<std::string>{}, getRandomStringInputs)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_Compare_same_container, unordered_set_int, std::unordered_set<int>{}, getRandomIntegerInputs<int>)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(
+    BM_Compare_different_containers, unordered_set_string, std::unordered_set<std::string>{}, getRandomStringInputs)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(
+    BM_Compare_different_containers, unordered_set_int, std::unordered_set<int>{}, getRandomIntegerInputs<int>)
+    ->Arg(TestNumInputs);
+
 ///////////////////////////////////////////////////////////////////////////////
 BENCHMARK_CAPTURE(BM_InsertDuplicate, unordered_set_int, std::unordered_set<int>{}, getRandomIntegerInputs<int>)
     ->Arg(TestNumInputs);