commit 8444e5ce5575a93a270c8c48081693f6ae9ed9d1
Author: Stefan Bühler <stbuehler@web.de>
Date:   Sat Jul 19 15:35:25 2014 +0200

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1ff49ea
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*-build
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..d971ac5
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,54 @@
+cmake_minimum_required(VERSION 2.8.8 FATAL_ERROR)
+project(c++-benchmarks CXX)
+
+include(CMakeDetermineCXXCompiler)
+
+# default to Release
+if("${CMAKE_BUILD_TYPE}" STREQUAL "")
+	set(CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build, options are: None(CMAKE_CXX_FLAGS or CMAKE_C_FLAGS used) Debug Release RelWithDebInfo MinSizeRel." FORCE)
+endif("${CMAKE_BUILD_TYPE}" STREQUAL "")
+
+
+if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+	set(EXTRA_CXX_FLAGS "-std=c++11 -Wall -Wextra -Wno-unused-parameter -pedantic" CACHE STRING "Extra flags used by the compiler during all build types.")
+else("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+	set(EXTRA_CXX_FLAGS "" CACHE STRING "Extra flags used by the compiler during all build types.")
+endif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXX_FLAGS}")
+
+add_executable(benchmark-atomic-costs
+	benchmark-atomic-costs.cpp)
+
+add_executable(benchmark-atomic-costs-pthread
+	benchmark-atomic-costs.cpp)
+set_target_properties(benchmark-atomic-costs-pthread
+	PROPERTIES
+		COMPILE_FLAGS "-pthread"
+		LINK_FLAGS "-pthread")
+
+add_executable(benchmark-shared-unique
+	benchmark-shared-unique.cpp
+	benchmark-shared-unique-impl.cpp)
+
+add_executable(test-NULL-type
+	test-NULL-type.cpp)
+
+add_executable(test-base-constr
+	test-base-constr.cpp)
+
+add_executable(test-const-ref-results
+	test-const-ref-results.cpp)
+
+add_executable(test-constructor-throw
+	test-constructor-throw.cpp)
+
+add_executable(test-copy-shared-ptr
+	test-copy-shared-ptr.cpp
+	test-copy-shared-ptr-impl.cpp)
+
+add_executable(test-rvalue-ref
+	test-rvalue-ref.cpp)
+
+add_executable(test-smart-factory
+	test-smart-factory.cpp)
diff --git a/benchmark-atomic-costs.cpp b/benchmark-atomic-costs.cpp
new file mode 100644
index 0000000..136a5c7
--- /dev/null
+++ b/benchmark-atomic-costs.cpp
@@ -0,0 +1,102 @@
+
+#include "measure_time.h"
+
+#include <atomic>
+#include <cstdint>
+#include <thread>
+#include <ext/concurrence.h>
+
+#define COUNT (1u << 24)
+
+// use "incl" for 32-bit and "incq" for 64-bit in asm below:
+// use 32-bit for now: _Atomic_word should be 32-bit too;
+// 64-bit is basically as fast as 32-bit if it fits in your cache
+typedef std::uint32_t counting;
+
+volatile counting __attribute__ ((aligned (64))) volatile_counter;
+counting __attribute__ ((aligned (64))) simple_counter;
+std::atomic<counting> __attribute__ ((aligned (64))) atomic_counter;
+
+_Atomic_word __attribute__ ((aligned (64))) gxx_counter;
+
+void benchmark_volatile() {
+	// should be the same as asm below
+	volatile_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		++volatile_counter;
+	}
+}
+
+void benchmark_asm() {
+	simple_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		asm volatile(
+			"incl %0;"
+			: "+m"(simple_counter)
+		);
+	}
+}
+
+void benchmark_local_atomic() {
+	// compiler doesn't realize no one else can read this counter and
+	// uses real atomic (i.e. "lock")
+	std::atomic<counting> local_atomic_counter;
+	local_atomic_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		++local_atomic_counter;
+	}
+}
+
+void benchmark_atomic() {
+	// should be the same as "lock_asm"
+	atomic_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		++atomic_counter;
+	}
+}
+
+void benchmark_lock_asm() {
+	simple_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		asm volatile(
+			"lock incl %0;"
+			: "+m"(simple_counter)
+		);
+	}
+}
+
+void benchmark_gxx_atomic() {
+	// if linked with pthread this will use "lock" same as atomic, otherwise
+	// it uses a simple non-volatile non-atomic add instruction
+	// https://gcc.gnu.org/onlinedocs/libstdc++/manual/ext_concurrency.html
+	// claims __atomic_add_dispatch uses a volatile counter, but this isn't
+	// true in gcc 4.9
+	gxx_counter = 0;
+	for (size_t i = 0; i < COUNT; ++i) {
+		__gnu_cxx::__atomic_add_dispatch(&gxx_counter, 1);
+	}
+}
+
+
+int main() {
+//	std::thread fake([] { return; });
+//	fake.join();
+
+	std::cout << "volatile counter    : ";
+	measure_time_with_dry_run(benchmark_volatile);
+
+	std::cout << "asm counter         : ";
+	measure_time_with_dry_run(benchmark_asm);
+
+	std::cout << "local atomic counter: ";
+	measure_time_with_dry_run(benchmark_local_atomic);
+
+	std::cout << "atomic counter      : ";
+	measure_time_with_dry_run(benchmark_atomic);
+
+	std::cout << "lock asm counter    : ";
+	measure_time_with_dry_run(benchmark_lock_asm);
+
+	std::cout << "gxx atomic counter  : ";
+	measure_time_with_dry_run(benchmark_gxx_atomic);
+}
diff --git a/benchmark-results.txt b/benchmark-results.txt
new file mode 100644
index 0000000..e69de29
diff --git a/benchmark-shared-unique-impl.cpp b/benchmark-shared-unique-impl.cpp
new file mode 100644
index 0000000..f1261ba
--- /dev/null
+++ b/benchmark-shared-unique-impl.cpp
@@ -0,0 +1,23 @@
+
+#include "benchmark-shared-unique.h"
+
+void* forward_raw(void* p) {
+	return p;
+}
+
+
+std::unique_ptr<size_t> forward_unique(std::unique_ptr<size_t>&& p) {
+	return std::move(p);
+}
+
+std::shared_ptr<size_t> forward_shared(std::shared_ptr<size_t>&& p) {
+	return std::move(p);
+}
+
+std::unique_ptr<Large> forward_unique_large(std::unique_ptr<Large>&& p) {
+	return std::move(p);
+}
+
+std::shared_ptr<Large> forward_shared_large(std::shared_ptr<Large>&& p) {
+	return std::move(p);
+}
diff --git a/benchmark-shared-unique.cpp b/benchmark-shared-unique.cpp
new file mode 100644
index 0000000..c8c4a53
--- /dev/null
+++ b/benchmark-shared-unique.cpp
@@ -0,0 +1,128 @@
+
+#include "benchmark-shared-unique.h"
+
+#include "measure_time.h"
+#include "make_unique.h"
+
+
+#define COUNT (1u << 26)
+
+void benchmark_forward_empty_raw() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_raw(nullptr);
+	}
+}
+
+void benchmark_forward_empty_unique() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_unique({});
+	}
+}
+
+void benchmark_forward_empty_shared() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared({});
+	}
+}
+
+void benchmark_forward_empty_shared_from_unique() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared(std::unique_ptr<size_t>{});
+	}
+}
+
+
+void benchmark_forward_new_raw() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		size_t* p = new size_t{i};
+		(void) forward_raw(p);
+		delete p;
+	}
+}
+
+void benchmark_forward_new_unique() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_unique(std::make_unique<size_t>(i));
+	}
+}
+
+void benchmark_forward_new_shared() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared(std::make_shared<size_t>(i));
+	}
+}
+
+void benchmark_forward_new_shared_from_unique() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared(std::make_unique<size_t>(i));
+	}
+}
+
+
+void benchmark_forward_new_raw_large() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		Large* p = new Large{i};
+		(void) forward_raw(p);
+		delete p;
+	}
+}
+
+void benchmark_forward_new_unique_large() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_unique_large(std::make_unique<Large>(i));
+	}
+}
+
+void benchmark_forward_new_shared_large() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared_large(std::make_shared<Large>(i));
+	}
+}
+
+void benchmark_forward_new_shared_large_from_unique() {
+	for (size_t i = 0; i < COUNT; ++i) {
+		(void) forward_shared_large(std::make_unique<Large>(i));
+	}
+}
+
+int main() {
+	std::cout << "forward empty raw                   : ";
+	measure_time(benchmark_forward_empty_raw);
+
+	std::cout << "forward empty unique                : ";
+	measure_time(benchmark_forward_empty_unique);
+
+	std::cout << "forward empty shared                : ";
+	measure_time(benchmark_forward_empty_shared);
+
+	std::cout << "forward empty shared from unique    : ";
+	measure_time(benchmark_forward_empty_shared_from_unique);
+
+	std::cout << "\n";
+
+	std::cout << "forward new raw                     : ";
+	measure_time(benchmark_forward_new_raw);
+
+	std::cout << "forward new unique                  : ";
+	measure_time(benchmark_forward_new_unique);
+
+	std::cout << "forward new shared                  : ";
+	measure_time(benchmark_forward_new_shared);
+
+	std::cout << "forward new shared from unique      : ";
+	measure_time(benchmark_forward_new_shared_from_unique);
+
+	std::cout << "\n";
+
+	std::cout << "forward new raw large               : ";
+	measure_time(benchmark_forward_new_raw_large);
+
+	std::cout << "forward new unique large            : ";
+	measure_time(benchmark_forward_new_unique_large);
+
+	std::cout << "forward new shared large            : ";
+	measure_time(benchmark_forward_new_shared_large);
+
+	std::cout << "forward new shared large from unique: ";
+	measure_time(benchmark_forward_new_shared_large_from_unique);
+}
diff --git a/benchmark-shared-unique.h b/benchmark-shared-unique.h
new file mode 100644
index 0000000..1f593b2
--- /dev/null
+++ b/benchmark-shared-unique.h
@@ -0,0 +1,16 @@
+#include <memory>
+
+struct Large {
+	size_t x;
+	char filler[512 - sizeof(size_t)] = {};
+
+	Large(size_t x) : x(x) {}
+};
+
+void* forward_raw(void* p);
+
+std::unique_ptr<size_t> forward_unique(std::unique_ptr<size_t>&& p);
+std::shared_ptr<size_t> forward_shared(std::shared_ptr<size_t>&& p);
+
+std::unique_ptr<Large> forward_unique_large(std::unique_ptr<Large>&& p);
+std::shared_ptr<Large> forward_shared_large(std::shared_ptr<Large>&& p);
diff --git a/make_unique.h b/make_unique.h
new file mode 100644
index 0000000..efc04b5
--- /dev/null
+++ b/make_unique.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <memory>
+
+#if __cplusplus <= 201103L
+
+namespace {
+  template<class T>
+  struct is_unbound_array : std::false_type {};
+
+  template<class T>
+  struct is_unbound_array<T[]> : std::true_type {};
+
+  template<class T>
+  struct is_bound_array : std::false_type {};
+
+  template<class T, std::size_t N>
+  struct is_bound_array<T[N]> : std::true_type {};
+}
+
+namespace std {
+  template<typename T, typename... Args>
+  typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type make_unique(Args&&... args) {
+      return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+  }
+
+  template<typename T>
+  typename std::enable_if<is_unbound_array<T>::value, std::unique_ptr<T>>::type make_unique(size_t size) {
+      return std::unique_ptr<T>(new typename std::remove_extent<T>::type[size]());
+  }
+
+  template< class T, class... Args >
+  typename std::enable_if<is_bound_array<T>::value>::type make_unique( Args&&... args ) = delete;
+}
+
+#endif
diff --git a/measure_time.h b/measure_time.h
new file mode 100644
index 0000000..bf33b27
--- /dev/null
+++ b/measure_time.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <chrono>
+#include <iostream>
+
+template<typename Callable>
+void measure_time(Callable&& callable) {
+	using namespace std::chrono;
+	steady_clock::time_point t_start = steady_clock::now();
+	callable();
+	duration<double> time_span = duration_cast<duration<double>>(steady_clock::now() - t_start);
+
+	std::cout << "took " << time_span.count() << " seconds\n";
+}
+
+template<typename Callable>
+void measure_time_with_dry_run(Callable&& callable) {
+	callable();
+	measure_time(std::forward<Callable>(callable));
+}
diff --git a/test-NULL-type.cpp b/test-NULL-type.cpp
new file mode 100644
index 0000000..e14a85e
--- /dev/null
+++ b/test-NULL-type.cpp
@@ -0,0 +1,15 @@
+
+#include "type_name.h"
+
+#include <memory>
+#include <utility>
+#include <iostream>
+
+int main() {
+	auto o = NULL;
+	int* n(reinterpret_cast<int*>(o));
+	// auto n = std::make_pair(0, (intptr_t) NULL);
+	std::cout << "decltype(n) is " << TYPE_NAME(n) << '\n';
+	auto p = std::make_pair(std::ref(o), nullptr);
+	std::cout << "decltype(p) is " << TYPE_NAME(p) << '\n';
+}
diff --git a/test-base-constr.cpp b/test-base-constr.cpp
new file mode 100644
index 0000000..601645b
--- /dev/null
+++ b/test-base-constr.cpp
@@ -0,0 +1,30 @@
+
+#include <iostream>
+
+#define L(s) std::cerr << s << "\n"
+
+struct A {
+	A() { L("A::A()"); }
+	A(A&&) { L("A::A(A&&)"); }
+	A(const A&) { L("A::A(const A&)"); }
+	~A() { L("A::~A()"); }
+};
+
+struct B: A {
+	B() { L("B::B()"); }
+	B(A&&) { L("B::B(A&&)"); }
+	//B(B&&) { L("B::B(B&&)"); }
+	B(const A&) { L("B::B(const A&)"); }
+	// B(const B&) { L("B::B(const B&)"); }
+	~B() { L("B::~B()"); }
+};
+
+int main() {
+	L("A a1;");
+	A a1;
+	L("B b1(a1);");
+	B b1(a1);
+	L("B b1(b1);");
+	B b2(static_cast<A&>(b1));
+	return 0;
+}
diff --git a/test-const-ref-results.cpp b/test-const-ref-results.cpp
new file mode 100644
index 0000000..2f778a3
--- /dev/null
+++ b/test-const-ref-results.cpp
@@ -0,0 +1,22 @@
+#include <algorithm>
+#include <memory>
+#include <iostream>
+
+class C {
+public:
+	int valid;
+	C() : valid(1) { }
+	~C() { valid = 0; }
+};
+
+/* some "random" comparison, doesn't matter */
+bool operator<(C const& a, C const& b) {
+	return reinterpret_cast<uintptr_t>(&a) < reinterpret_cast<uintptr_t>(&b);
+}
+
+int main() {
+	auto const& m =
+		// std::max(*std::make_shared<C>(), *std::make_shared<C>());
+		std::max(C(), C());
+	std::cout << m.valid << "\n";
+}
diff --git a/test-constructor-throw.cpp b/test-constructor-throw.cpp
new file mode 100644
index 0000000..a468ed1
--- /dev/null
+++ b/test-constructor-throw.cpp
@@ -0,0 +1,35 @@
+
+#include <exception>
+#include <memory>
+#include <type_traits>
+
+#include "make_unique.h"
+
+struct C {
+private:
+  struct private_type { };
+  C(private_type) { }
+  int *m_i = nullptr;
+
+public:
+  C() : C(private_type()) { m_i = new int; throw std::exception(); }
+  ~C() { delete m_i; }
+  C(C const&) = delete;
+  C& operator=(C const&) = delete;
+};
+
+
+struct D {
+	std::unique_ptr<int> m_i;
+	D() : m_i(std::make_unique<int>()) { m_i = std::make_unique<int>(); throw std::exception(); }
+};
+
+int main() {
+	try {
+		C c;
+	} catch (...) { }
+
+	auto a = std::make_unique<int[]>(10);
+
+	return 0;
+}
diff --git a/test-copy-shared-ptr-impl.cpp b/test-copy-shared-ptr-impl.cpp
new file mode 100644
index 0000000..9224ba0
--- /dev/null
+++ b/test-copy-shared-ptr-impl.cpp
@@ -0,0 +1,10 @@
+
+#include <memory>
+
+void copy_ptr(std::shared_ptr<int>& a, std::shared_ptr<int> const& b) {
+	a = b;
+}
+
+void move_ptr(std::shared_ptr<int>& a, std::shared_ptr<int>& b) {
+	a = std::move(b);
+}
diff --git a/test-copy-shared-ptr.cpp b/test-copy-shared-ptr.cpp
new file mode 100644
index 0000000..a28efaf
--- /dev/null
+++ b/test-copy-shared-ptr.cpp
@@ -0,0 +1,8 @@
+
+#include <memory>
+
+void copy_ptr(std::shared_ptr<int>& a, std::shared_ptr<int> const& b);
+void move_ptr(std::shared_ptr<int>& a, std::shared_ptr<int>& b);
+
+int main() {
+}
diff --git a/test-rvalue-ref.cpp b/test-rvalue-ref.cpp
new file mode 100644
index 0000000..26035c6
--- /dev/null
+++ b/test-rvalue-ref.cpp
@@ -0,0 +1,23 @@
+
+#include "type_name.h"
+
+#include <iostream>
+
+void f(const int&) {
+}
+
+#define T(v) std::cout << #v << ": " << TYPE_NAME(v) << "\n"
+
+int main() {
+	auto&& i = 1;
+	auto& ri = i;
+	auto const& x = std::move(ri);
+	decltype(ri) y = ri;
+	f(i);
+//	f(std::forward(i));
+	T(i);
+	T(ri);
+	T(x);
+	T(y);
+	return 0;
+}
diff --git a/test-smart-factory.cpp b/test-smart-factory.cpp
new file mode 100644
index 0000000..fd10792
--- /dev/null
+++ b/test-smart-factory.cpp
@@ -0,0 +1,118 @@
+
+#include <memory>
+#include <type_traits>
+
+class C {
+protected:
+  struct Protected {
+  private:
+    Protected() {};
+  public:
+    static Protected make() { return { }; }
+  };
+  int m_x;
+
+private:
+  struct Private {
+  private:
+    Private() {};
+  public:
+    static Private make() { return { }; }
+  };
+  int m_y;
+
+public:
+  /* private constructor: */
+  C(Private, int x, int y) : m_x(x), m_y(y) { }
+  /* protected constructor: */
+  C(Protected, int x) : C(Private::make(), x, 2*x) { }
+
+  void leak_private_type(Private) { }
+
+  static std::unique_ptr<C> Create(int x) {
+    return std::unique_ptr<C>(new C(Private::make(), x, 2*x));
+  }
+};
+
+class D : public C {
+private:
+  struct Private { };
+public:
+  D(Private&, int x) : C(Protected::make(), x) { }
+
+  static std::shared_ptr<D> Create(int x) {
+    Private p;
+    return std::make_shared<D>(p, 4*x);
+  }
+};
+
+
+class A {
+   struct this_is_private {
+   };
+
+ public:
+   explicit A(const this_is_private &, int) {}
+
+   static ::std::shared_ptr<A> create(int x) {
+      return ::std::make_shared<A>(this_is_private{}, x);
+   }
+
+ protected:
+   A(const A &) = delete;
+   const A &operator =(const A &) = delete;
+};
+
+::std::shared_ptr<A> foo(int x)
+{
+   return A::create(x);
+}
+
+
+  /* usage: decltype(return_args(&Class::memberfunction)) */
+  template<typename Base, typename Result, typename... Args>
+  std::tuple<Args...> return_args(Result (Base::*func)(Args...));
+
+  /* usage: decltype(result_of(&Class::memberfunction)) */
+  template<typename Base, typename Result, typename... Args>
+  Result result_of(Result (Base::*func)(Args...));
+
+  /* usage: decay_tuple_element<0, decltype(return_args(&Class::memberfunction))> */
+  template <size_t i, typename Tuple>
+  using decay_tuple_element = typename std::decay<typename std::tuple_element<i, Tuple>::type>::type;
+
+
+  struct _is_static_castable_impl
+  {
+    template<typename _From, typename _To, typename = decltype(static_cast<_To>(std::declval<_From>()))>
+    static std::true_type __test(int);
+
+    template<typename, typename>
+    static std::false_type __test(...);
+  };
+
+  template<typename _From, typename _To>
+  struct is_static_castable
+  : public _is_static_castable_impl
+  {
+    typedef decltype(__test<_From, _To>(0)) type;
+  };
+
+  template<typename _From, typename _To>
+  using is_static_castable_t = typename is_static_castable<_From, _To>::type;
+
+
+
+int main() {
+  auto c = C::Create(0);
+  auto d = D::Create(0);
+
+  typedef decay_tuple_element<0, decltype(return_args(&C::leak_private_type))> Private;
+  Private::make();
+
+
+  auto a1 = foo(0);
+  auto a2 = std::shared_ptr<A>(new A({}, 0));
+
+//  C c1({}, 0, 0);
+}
diff --git a/type_name.h b/type_name.h
new file mode 100644
index 0000000..d6b6032
--- /dev/null
+++ b/type_name.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include <type_traits>
+#include <typeinfo>
+#ifndef _MSC_VER
+# include <cxxabi.h>
+#endif
+#include <memory>
+#include <string>
+#include <cstdlib>
+
+template <class T>
+std::string
+type_name()
+{
+	typedef typename std::remove_reference<T>::type TR;
+	std::unique_ptr<char, void(*)(void*)> own
+		(
+#ifndef _MSC_VER
+			abi::__cxa_demangle(typeid(TR).name(), nullptr, nullptr, nullptr),
+#else
+			nullptr,
+#endif
+			std::free
+		);
+	std::string r = own != nullptr ? own.get() : typeid(TR).name();
+	if (std::is_const<TR>::value)
+		r += " const";
+	if (std::is_volatile<TR>::value)
+		r += " volatile";
+	if (std::is_lvalue_reference<T>::value)
+		r += "&";
+	else if (std::is_rvalue_reference<T>::value)
+		r += "&&";
+	return r;
+}
+
+#define TYPE_NAME(p) (type_name<decltype(p)>())