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shared_ptr.hpp: fix critical bugs

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Fix array initialization.
Fix reference counting.
Fix offset to refctr.
Add some features.
This commit is contained in:
Nekotekina 2020-11-27 10:00:52 +03:00
parent 0892758994
commit 872655369a
2 changed files with 155 additions and 59 deletions
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1
rpcs3/stdafx.h
View file

@ -26,6 +26,7 @@ namespace std { inline namespace literals { inline namespace chrono_literals {}}
#include "Utilities/StrFmt.h"
#include "Utilities/File.h"
#include "util/logs.hpp"
#include "util/shared_ptr.hpp"
#include <cstdlib>
#include <cstring>

213
rpcs3/util/shared_ptr.hpp
View file

@ -6,12 +6,21 @@
namespace stx
{
template <typename T, typename U>
constexpr bool is_same_ptr() noexcept
{
// Should be possible if constexpr bit_cast is available?
// Otherwise I hope it will compile in null code anyway.
const auto u = reinterpret_cast<U*>(0x11223344556);
return static_cast<T*>(u) == static_cast<void*>(u);
}
// TODO
template <typename T, typename U>
constexpr bool is_same_ptr_v = true;
template <typename T, typename U>
constexpr bool is_same_ptr_cast_v = std::is_convertible_v<U, T> && is_same_ptr_v<T, U>;
constexpr bool is_same_ptr_cast_v = std::is_same_v<T, U> || std::is_convertible_v<U, T> && is_same_ptr_v<T, U>;
template <typename T>
class single_ptr;
@ -31,63 +40,62 @@ namespace stx
struct shared_counter
{
// Stored destructor
void (*destroy)(void* ptr);
void (*destroy)(shared_counter* _this);
// Reference counter
atomic_t<std::size_t> refs{0};
atomic_t<std::size_t> refs{1};
};
template <typename T>
class unique_data
template <std::size_t Size, std::size_t Align, typename = void>
struct align_filler
{
public:
T data;
template <typename... Args>
explicit constexpr unique_data(Args&&... args) noexcept
: data(std::forward<Args>(args)...)
{
}
};
template <typename T>
class unique_data<T[]>
template <std::size_t Size, std::size_t Align>
struct align_filler<Size, Align, std::enable_if_t<(Align > Size)>>
{
std::size_t count;
char dummy[Align - Size];
};
// Control block with data and reference counter
template <typename T>
class alignas(T) shared_data final : public shared_counter, public unique_data<T>
class alignas(T) shared_data final : align_filler<sizeof(shared_counter), alignof(T)>
{
public:
using data_type = T;
shared_counter m_ctr;
T m_data;
template <typename... Args>
explicit constexpr shared_data(Args&&... args) noexcept
: shared_counter{}
, unique_data<T>(std::forward<Args>(args)...)
: m_ctr{}
, m_data(std::forward<Args>(args)...)
{
}
};
template <typename T>
class alignas(T) shared_data<T[]> final : public shared_counter, public unique_data<T>
class alignas(T) shared_data<T[]> final : align_filler<sizeof(shared_counter) + sizeof(std::size_t), alignof(T)>
{
public:
using data_type = T;
std::size_t m_count;
shared_counter m_ctr;
constexpr shared_data() noexcept = default;
};
// Simplified unique pointer (well, not simplified, std::unique_ptr is preferred)
// Simplified unique pointer. Wwell, not simplified, std::unique_ptr is preferred.
// This one is shared_ptr counterpart, it has a control block with refs = 1.
template <typename T>
class single_ptr
{
std::remove_extent_t<T>* m_ptr{};
shared_data<T>* d() const noexcept
shared_counter* d() const noexcept
{
// Shared counter, deleter, should be at negative offset
return std::launder(static_cast<shared_data<T>*>(reinterpret_cast<unique_data<T>*>(m_ptr)));
return std::launder(reinterpret_cast<shared_counter*>(reinterpret_cast<u64>(m_ptr) - sizeof(shared_counter)));
}
template <typename U>
@ -117,6 +125,7 @@ namespace stx
single_ptr(single_ptr<U>&& r) noexcept
: m_ptr(r.m_ptr)
{
verify(HERE), is_same_ptr<T, U>();
r.m_ptr = nullptr;
}
@ -142,6 +151,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
single_ptr& operator=(single_ptr<U>&& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
m_ptr = r.m_ptr;
r.m_ptr = nullptr;
return *this;
@ -151,7 +161,8 @@ namespace stx
{
if (m_ptr) [[likely]]
{
d()->destroy(d());
const auto o = d();
o->destroy(o);
m_ptr = nullptr;
}
}
@ -203,42 +214,80 @@ namespace stx
{
return m_ptr != nullptr;
}
// "Moving" "static cast"
template <typename U, typename = decltype(static_cast<U*>(std::declval<T*>())), typename = std::enable_if_t<is_same_ptr_v<U, T>>>
explicit operator single_ptr<U>() && noexcept
{
verify(HERE), is_same_ptr<U, T>();
single_ptr<U> r;
r.m_ptr = static_cast<decltype(r.m_ptr)>(std::exchange(m_ptr, nullptr));
return r;
}
};
template <typename T, bool Init = true, typename... Args>
static std::enable_if_t<!(std::is_unbounded_array_v<T>) && (Init || !sizeof...(Args)), single_ptr<T>> make_single(Args&&... args) noexcept
{
static_assert(offsetof(shared_data<T>, m_data) - offsetof(shared_data<T>, m_ctr) == sizeof(shared_counter));
using etype = std::remove_extent_t<T>;
shared_data<T>* ptr = nullptr;
if constexpr (Init)
if constexpr (Init && !std::is_array_v<T>)
{
ptr = new shared_data<T>(std::forward<Args>(args)...);
}
else
{
ptr = new shared_data<T>;
if constexpr (Init && std::is_array_v<T>)
{
// Weird case, destroy and reinitialize every fixed array arg (fill)
for (auto& e : ptr->m_data)
{
e.~etype();
new (&e) etype(std::forward<Args>(args)...);
}
}
}
ptr->destroy = [](void* p)
ptr->m_ctr.destroy = [](shared_counter* _this)
{
delete static_cast<shared_data<T>*>(p);
delete reinterpret_cast<shared_data<T>*>(reinterpret_cast<u64>(_this) - offsetof(shared_data<T>, m_ctr));
};
single_ptr<T> r;
reinterpret_cast<std::remove_extent_t<T>*&>(r) = &ptr->data;
if constexpr (std::is_array_v<T>)
{
reinterpret_cast<etype*&>(r) = +ptr->m_data;
}
else
{
reinterpret_cast<etype*&>(r) = &ptr->m_data;
}
return r;
}
template <typename T, bool Init = true>
static std::enable_if_t<std::is_unbounded_array_v<T>, single_ptr<T>> make_single(std::size_t count) noexcept
{
const std::size_t size = sizeof(shared_data<T>) + count * sizeof(std::remove_extent_t<T>);
static_assert(sizeof(shared_data<T>) - offsetof(shared_data<T>, m_ctr) == sizeof(shared_counter));
using etype = std::remove_extent_t<T>;
const std::size_t size = sizeof(shared_data<T>) + count * sizeof(etype);
std::byte* bytes = nullptr;
if constexpr (alignof(std::remove_extent_t<T>) > (__STDCPP_DEFAULT_NEW_ALIGNMENT__))
if constexpr (alignof(etype) > (__STDCPP_DEFAULT_NEW_ALIGNMENT__))
{
bytes = new (std::align_val_t{alignof(std::remove_extent_t<T>)}) std::byte[size];
bytes = new (std::align_val_t{alignof(etype)}) std::byte[size];
}
else
{
@ -249,7 +298,7 @@ namespace stx
shared_data<T>* ptr = new (reinterpret_cast<shared_data<T>*>(bytes)) shared_data<T>();
// Initialize array next to the control block
T arr = reinterpret_cast<T>(ptr + 1);
etype* arr = reinterpret_cast<etype*>(bytes + sizeof(shared_data<T>));
if constexpr (Init)
{
@ -262,21 +311,23 @@ namespace stx
ptr->m_count = count;
ptr->destroy = [](void* p)
ptr->m_ctr.destroy = [](shared_counter* _this)
{
shared_data<T>* ptr = static_cast<shared_data<T>*>(p);
shared_data<T>* ptr = reinterpret_cast<shared_data<T>*>(reinterpret_cast<u64>(_this) - offsetof(shared_data<T>, m_ctr));
std::destroy_n(std::launder(reinterpret_cast<T>(ptr + 1)), ptr->m_count);
std::byte* bytes = reinterpret_cast<std::byte*>(ptr);
std::destroy_n(std::launder(reinterpret_cast<etype*>(bytes + sizeof(shared_data<T>))), ptr->m_count);
ptr->~shared_data<T>();
if constexpr (alignof(std::remove_extent_t<T>) > (__STDCPP_DEFAULT_NEW_ALIGNMENT__))
if constexpr (alignof(etype) > (__STDCPP_DEFAULT_NEW_ALIGNMENT__))
{
::operator delete[](reinterpret_cast<std::byte*>(p), std::align_val_t{alignof(std::remove_extent_t<T>)});
::operator delete[](bytes, std::align_val_t{alignof(etype)});
}
else
{
delete[] reinterpret_cast<std::byte*>(p);
delete[] bytes;
}
};
@ -291,10 +342,10 @@ namespace stx
{
std::remove_extent_t<T>* m_ptr{};
shared_data<T>* d() const noexcept
shared_counter* d() const noexcept
{
// Shared counter, deleter, should be at negative offset
return std::launder(static_cast<shared_data<T>*>(reinterpret_cast<unique_data<T>*>(m_ptr)));
return std::launder(reinterpret_cast<shared_counter*>(reinterpret_cast<u64>(m_ptr) - sizeof(shared_counter)));
}
template <typename U>
@ -320,6 +371,7 @@ namespace stx
shared_ptr(const shared_ptr<U>& r) noexcept
: m_ptr(r.m_ptr)
{
verify(HERE), is_same_ptr<T, U>();
if (m_ptr)
d()->refs++;
}
@ -334,6 +386,7 @@ namespace stx
shared_ptr(shared_ptr<U>&& r) noexcept
: m_ptr(r.m_ptr)
{
verify(HERE), is_same_ptr<T, U>();
r.m_ptr = nullptr;
}
@ -341,6 +394,7 @@ namespace stx
shared_ptr(single_ptr<U>&& r) noexcept
: m_ptr(r.m_ptr)
{
verify(HERE), is_same_ptr<T, U>();
r.m_ptr = nullptr;
}
@ -358,6 +412,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
shared_ptr& operator=(const shared_ptr<U>& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
shared_ptr(r).swap(*this);
return *this;
}
@ -371,6 +426,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
shared_ptr& operator=(shared_ptr<U>&& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
shared_ptr(std::move(r)).swap(*this);
return *this;
}
@ -378,6 +434,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
shared_ptr& operator=(single_ptr<U>&& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
shared_ptr(std::move(r)).swap(*this);
return *this;
}
@ -385,22 +442,33 @@ namespace stx
// Set to null
void reset() noexcept
{
if (m_ptr && !--d()->refs) [[unlikely]]
const auto o = d();
if (m_ptr && !--o->refs) [[unlikely]]
{
d()->destroy(d());
o->destroy(o);
m_ptr = nullptr;
}
}
// Converts to unique (single) ptr if reference is 1, otherwise returns null. Nullifies self.
explicit operator single_ptr<T>() && noexcept
template <typename U, typename = decltype(static_cast<U*>(std::declval<T*>())), typename = std::enable_if_t<is_same_ptr_v<U, T>>>
explicit operator single_ptr<U>() && noexcept
{
if (m_ptr && !--d()->refs)
verify(HERE), is_same_ptr<U, T>();
const auto o = d();
if (m_ptr && !--o->refs)
{
d()->refs.release(1);
return {std::move(*this)};
// Convert last reference to single_ptr instance.
o->refs.release(1);
single_ptr<T> r;
r.m_ptr = static_cast<decltype(r.m_ptr)>(std::exchange(m_ptr, nullptr));
return r;
}
// Otherwise, both pointers are gone. Didn't seem right to do it in the constructor.
m_ptr = nullptr;
return {};
}
@ -465,16 +533,30 @@ namespace stx
return m_ptr != nullptr;
}
// Basic "static cast" support
template <typename U, typename = decltype(static_cast<U*>(std::declval<T*>())), typename = std::enable_if_t<is_same_ptr_v<U, T>>>
explicit operator shared_ptr<U>() const noexcept
explicit operator shared_ptr<U>() const& noexcept
{
verify(HERE), is_same_ptr<U, T>();
if (m_ptr)
{
d()->refs++;
}
shared_ptr<U> r;
r.m_ptr = m_ptr;
r.m_ptr = static_cast<decltype(r.m_ptr)>(m_ptr);
return r;
}
// "Moving" "static cast"
template <typename U, typename = decltype(static_cast<U*>(std::declval<T*>())), typename = std::enable_if_t<is_same_ptr_v<U, T>>>
explicit operator shared_ptr<U>() && noexcept
{
verify(HERE), is_same_ptr<U, T>();
shared_ptr<U> r;
r.m_ptr = static_cast<decltype(r.m_ptr)>(std::exchange(m_ptr, nullptr));
return r;
}
};
@ -497,12 +579,12 @@ namespace stx
{
mutable atomic_t<uptr> m_val{0};
static shared_data<T>* d(uptr val)
static shared_counter* d(uptr val)
{
return std::launder(static_cast<shared_data<T>*>(reinterpret_cast<unique_data<T>*>(val >> c_ref_size)));
return std::launder(reinterpret_cast<shared_counter*>((val >> c_ref_size) - sizeof(shared_counter)));
}
shared_data<T>* d() const noexcept
shared_counter* d() const noexcept
{
return d(m_val);
}
@ -529,6 +611,8 @@ namespace stx
atomic_ptr(const shared_ptr<U>& r) noexcept
: m_val(reinterpret_cast<uptr>(r.m_ptr) << c_ref_size)
{
verify(HERE), is_same_ptr<T, U>();
// Obtain a ref + as many refs as an atomic_ptr can additionally reference
if (m_val)
d()->refs += c_ref_mask + 1;
@ -538,6 +622,7 @@ namespace stx
atomic_ptr(shared_ptr<U>&& r) noexcept
: m_val(reinterpret_cast<uptr>(r.m_ptr) << c_ref_size)
{
verify(HERE), is_same_ptr<T, U>();
r.m_ptr = nullptr;
if (m_val)
@ -548,6 +633,7 @@ namespace stx
atomic_ptr(single_ptr<U>&& r) noexcept
: m_val(reinterpret_cast<uptr>(r.m_ptr) << c_ref_size)
{
verify(HERE), is_same_ptr<T, U>();
r.m_ptr = nullptr;
if (m_val)
@ -557,10 +643,11 @@ namespace stx
~atomic_ptr()
{
const uptr v = m_val.raw();
const auto o = d(v);
if (v && !d(v)->refs.sub_fetch(c_ref_mask + 1 - (v & c_ref_mask)))
if (v >> c_ref_size && !o->refs.sub_fetch(c_ref_mask + 1 - (v & c_ref_mask)))
{
d(v)->destroy(d(v));
o->destroy(o);
}
}
@ -574,6 +661,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
atomic_ptr& operator=(const shared_ptr<U>& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
store(r);
return *this;
}
@ -581,6 +669,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
atomic_ptr& operator=(shared_ptr<U>&& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
store(std::move(r));
return *this;
}
@ -588,6 +677,7 @@ namespace stx
template <typename U, typename = std::enable_if_t<is_same_ptr_cast_v<T, U>>>
atomic_ptr& operator=(single_ptr<U>&& r) noexcept
{
verify(HERE), is_same_ptr<T, U>();
store(std::move(r));
return *this;
}
@ -616,6 +706,7 @@ namespace stx
// Set referenced pointer
r.m_ptr = std::launder(reinterpret_cast<element_type*>(prev >> c_ref_size));
r.d()->refs++;
// Dereference if same pointer
m_val.fetch_op([prev = prev](uptr& val)
@ -651,19 +742,23 @@ namespace stx
[[nodiscard]] shared_type exchange(shared_type value) noexcept
{
atomic_ptr old;
if (value.m_ptr)
{
// Consume value and add refs
value.d()->refs += c_ref_mask;
old.m_val.raw() += 1;
}
atomic_ptr old;
old.m_val.raw() += m_val.exchange(reinterpret_cast<uptr>(std::exchange(value.m_ptr, nullptr)) << c_ref_size);
shared_type r;
r.m_ptr = old.m_val >> c_ref_size;
r.m_ptr = std::launder(reinterpret_cast<element_type*>(old.m_val >> c_ref_size));
if (old.m_val.raw())
{
old.m_val.raw()++;
}
return r;
}