From c4952da40109ad73cb50225cdd28a55161c64111 Mon Sep 17 00:00:00 2001
From: Eric Fiselier <eric@efcs.ca>
Date: Fri, 2 Aug 2019 21:13:38 +0000
Subject: [PATCH] Add benchmarks to test the cost of allocator

llvm-svn: 367722
---
 libcxx/benchmarks/CMakeLists.txt       |   2 +
 libcxx/benchmarks/allocation.bench.cpp | 136 +++++++++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 libcxx/benchmarks/allocation.bench.cpp

diff --git a/libcxx/benchmarks/CMakeLists.txt b/libcxx/benchmarks/CMakeLists.txt
index 906ffa441427..d80cb1af03a0 100644
--- a/libcxx/benchmarks/CMakeLists.txt
+++ b/libcxx/benchmarks/CMakeLists.txt
@@ -84,6 +84,7 @@ endif()
 
 set(BENCHMARK_TEST_COMPILE_FLAGS
     ${BENCHMARK_DIALECT_FLAG} -O2
+    -fsized-deallocation
     -I${BENCHMARK_LIBCXX_INSTALL}/include
     -I${LIBCXX_SOURCE_DIR}/test/support
 )
@@ -219,3 +220,4 @@ if (LIBCXX_INCLUDE_TESTS)
           DEPENDS cxx-benchmarks ${LIBCXX_TEST_DEPS}
           ARGS ${BENCHMARK_LIT_ARGS})
 endif()
+
diff --git a/libcxx/benchmarks/allocation.bench.cpp b/libcxx/benchmarks/allocation.bench.cpp
new file mode 100644
index 000000000000..236e74044a56
--- /dev/null
+++ b/libcxx/benchmarks/allocation.bench.cpp
@@ -0,0 +1,136 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "benchmark/benchmark.h"
+
+#include <new>
+#include <vector>
+#include <cassert>
+
+struct PointerList {
+  PointerList* Next = nullptr;
+};
+
+struct MallocWrapper {
+  __attribute__((always_inline))
+  static void* Allocate(size_t N) {
+    return std::malloc(N);
+  }
+  __attribute__((always_inline))
+  static void Deallocate(void* P, size_t) {
+    std::free(P);
+  }
+};
+
+struct NewWrapper {
+  __attribute__((always_inline))
+  static void* Allocate(size_t N) {
+    return ::operator new(N);
+  }
+  __attribute__((always_inline))
+  static void Deallocate(void* P, size_t) {
+    ::operator delete(P);
+  }
+};
+
+struct BuiltinNewWrapper {
+  __attribute__((always_inline))
+  static void* Allocate(size_t N) {
+    return __builtin_operator_new(N);
+  }
+  __attribute__((always_inline))
+  static void Deallocate(void* P, size_t) {
+    __builtin_operator_delete(P);
+  }
+};
+
+struct BuiltinSizedNewWrapper {
+  __attribute__((always_inline))
+  static void* Allocate(size_t N) {
+    return __builtin_operator_new(N);
+  }
+  __attribute__((always_inline))
+  static void Deallocate(void* P, size_t N) {
+    __builtin_operator_delete(P, N);
+  }
+};
+
+
+template <class AllocWrapper>
+static void BM_AllocateAndDeallocate(benchmark::State& st) {
+  const size_t alloc_size = st.range(0);
+  while (st.KeepRunning()) {
+    void* p = AllocWrapper::Allocate(alloc_size);
+    benchmark::DoNotOptimize(p);
+    AllocWrapper::Deallocate(p, alloc_size);
+  }
+}
+
+
+template <class AllocWrapper>
+static void BM_AllocateOnly(benchmark::State& st) {
+  const size_t alloc_size = st.range(0);
+  PointerList *Start = nullptr;
+
+  while (st.KeepRunning()) {
+    PointerList* p = (PointerList*)AllocWrapper::Allocate(alloc_size);
+    benchmark::DoNotOptimize(p);
+    p->Next = Start;
+    Start = p;
+  }
+
+  PointerList *Next = Start;
+  while (Next) {
+    PointerList *Tmp = Next;
+    Next = Tmp->Next;
+    AllocWrapper::Deallocate(Tmp, alloc_size);
+  }
+}
+
+template <class AllocWrapper>
+static void BM_DeallocateOnly(benchmark::State& st) {
+  const size_t alloc_size = st.range(0);
+  const auto NumAllocs = st.max_iterations;
+
+  using PtrT = void*;
+  std::vector<void*> Pointers(NumAllocs);
+  for (auto& p : Pointers) {
+    p = AllocWrapper::Allocate(alloc_size);
+  }
+
+  void** Data = Pointers.data();
+  void** const End = Pointers.data() + Pointers.size();
+  while (st.KeepRunning()) {
+    AllocWrapper::Deallocate(*Data, alloc_size);
+    Data += 1;
+  }
+  assert(Data == End);
+}
+
+static int RegisterAllocBenchmarks() {
+  using FnType = void(*)(benchmark::State&);
+  struct {
+    const char* name;
+    FnType func;
+  } TestCases[] = {
+      {"BM_Malloc", &BM_AllocateAndDeallocate<MallocWrapper>},
+      {"BM_New", &BM_AllocateAndDeallocate<NewWrapper>},
+      {"BM_BuiltinNewDelete", BM_AllocateAndDeallocate<BuiltinNewWrapper>},
+      {"BM_BuiltinSizedNewDelete", BM_AllocateAndDeallocate<BuiltinSizedNewWrapper>},
+      {"BM_BuiltinNewAllocateOnly", BM_AllocateOnly<BuiltinSizedNewWrapper>},
+      {"BM_BuiltinNewSizedDeallocateOnly", BM_DeallocateOnly<BuiltinSizedNewWrapper>},
+
+  };
+  for (auto TC : TestCases) {
+    benchmark::RegisterBenchmark(TC.name, TC.func)->Range(16, 4096 * 2);
+  }
+  return 0;
+}
+int Sink = RegisterAllocBenchmarks();
+
+BENCHMARK_MAIN();