luau/EqSat/include/Luau/Language.h
2024-06-02 19:41:34 -07:00

449 lines
10 KiB
C++

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#pragma once
#include "Luau/Id.h"
#include "Luau/Slice.h"
#include <array>
#include <algorithm>
#include <type_traits>
#include <utility>
#define LUAU_EQSAT_ATOM(name, t) \
struct name : public ::Luau::EqSat::Atom<name, t> \
{ \
static constexpr const char* tag = #name; \
using Atom::Atom; \
}
#define LUAU_EQSAT_NODE_ARRAY(name, ops) \
struct name : public ::Luau::EqSat::NodeVector<name, std::array<::Luau::EqSat::Id, ops>> \
{ \
static constexpr const char* tag = #name; \
using NodeVector::NodeVector; \
}
#define LUAU_EQSAT_NODE_VECTOR(name) \
struct name : public ::Luau::EqSat::NodeVector<name, std::vector<::Luau::EqSat::Id>> \
{ \
static constexpr const char* tag = #name; \
using NodeVector::NodeVector; \
}
#define LUAU_EQSAT_FIELD(name) \
struct name : public ::Luau::EqSat::Field<name> \
{ \
}
#define LUAU_EQSAT_NODE_FIELDS(name, ...) \
struct name : public ::Luau::EqSat::NodeFields<name, __VA_ARGS__> \
{ \
static constexpr const char* tag = #name; \
using NodeFields::NodeFields; \
}
namespace Luau::EqSat
{
template<typename T, typename = void>
struct LanguageHash
{
size_t operator()(const T&) const
{
// See available specializations at the bottom of this file.
static_assert(false, "missing languageHash specialization");
}
};
template <typename T>
std::size_t languageHash(const T& lang)
{
return LanguageHash<T>{}(lang);
}
template<typename Phantom, typename T>
struct Atom
{
Atom(const T& value)
: _value(value)
{
}
const T& value() const
{
return _value;
}
public:
Slice<Id> operands()
{
return {};
}
Slice<Id> operands() const
{
return {};
}
bool operator==(const Atom& rhs) const
{
return _value == rhs._value;
}
bool operator!=(const Atom& rhs) const
{
return !(*this == rhs);
}
struct Hash
{
size_t operator()(const Atom& value) const
{
return languageHash(value._value);
}
};
private:
T _value;
};
template<typename Phantom, typename T>
struct NodeVector
{
template<typename... Args>
NodeVector(Args&&... args)
: vector{std::forward<Args>(args)...}
{
}
const Id& operator[](size_t i) const
{
return vector[i];
}
public:
Slice<Id> operands()
{
return Slice{vector.data(), vector.size()};
}
Slice<const Id> operands() const
{
return Slice{vector.data(), vector.size()};
}
bool operator==(const NodeVector& rhs) const
{
return vector == rhs.vector;
}
bool operator!=(const NodeVector& rhs) const
{
return !(*this == rhs);
}
struct Hash
{
size_t operator()(const NodeVector& value) const
{
return languageHash(value.vector);
}
};
private:
T vector;
};
/// Empty base class just for static_asserts.
struct FieldBase
{
FieldBase() = delete;
FieldBase(FieldBase&&) = delete;
FieldBase& operator=(FieldBase&&) = delete;
FieldBase(const FieldBase&) = delete;
FieldBase& operator=(const FieldBase&) = delete;
};
template<typename Phantom>
struct Field : FieldBase
{
};
template<typename Phantom, typename... Fields>
class NodeFields
{
static_assert(std::conjunction<std::is_base_of<FieldBase, Fields>...>::value);
std::array<Id, sizeof...(Fields)> array;
template<typename T>
static constexpr int getIndex()
{
constexpr int N = sizeof...(Fields);
constexpr bool is[N] = {std::is_same_v<std::decay_t<T>, Fields>...};
for (int i = 0; i < N; ++i)
if (is[i])
return i;
return -1;
}
public:
template<typename... Args>
NodeFields(Args&&... args)
: array{std::forward<Args>(args)...}
{
}
Slice<Id> operands()
{
return Slice{array};
}
Slice<Id> operands() const
{
return Slice{array};
}
template<typename T>
const Id& field() const
{
static_assert(std::disjunction_v<std::is_same<std::decay_t<T>, Fields>...>);
return array[getIndex<T>()];
}
bool operator==(const NodeFields& rhs) const
{
return array == rhs.array;
}
bool operator!=(const NodeFields& rhs) const
{
return !(*this == rhs);
}
struct Hash
{
size_t operator()(const NodeFields& value) const
{
return languageHash(value.array);
}
};
};
// `Language` is very similar to `Luau::Variant` with enough differences warranting a different type altogether.
//
// Firstly, where `Luau::Variant` uses an `int` to decide which type the variant currently holds, we use
// a `const char*` instead. We use the pointer address for tag checking, and the string buffer for stringification.
//
// Secondly, we need `Language` to have additional methods such as:
// - `children()` to get child operands,
// - `operator==` to decide equality, and
// - `hash()` function.
//
// And finally, each `T` in `Ts` have additional requirements which `Luau::Variant` doesn't need.
template<typename... Ts>
class Language final
{
const char* tag;
char buffer[std::max({sizeof(Ts)...})];
private:
template<typename T>
using WithinDomain = std::disjunction<std::is_same<std::decay_t<T>, Ts>...>;
using FnCopy = void (*)(void*, const void*);
using FnMove = void (*)(void*, void*);
using FnDtor = void (*)(void*);
using FnPred = bool (*)(const void*, const void*);
using FnHash = size_t (*)(const void*);
using FnOper = Slice<Id> (*)(void*);
template<typename T>
static void fnCopy(void* dst, const void* src) noexcept
{
new (dst) T(*static_cast<const T*>(src));
}
template<typename T>
static void fnMove(void* dst, void* src) noexcept
{
new (dst) T(static_cast<T&&>(*static_cast<T*>(src)));
}
template<typename T>
static void fnDtor(void* dst) noexcept
{
static_cast<T*>(dst)->~T();
}
template<typename T>
static bool fnPred(const void* lhs, const void* rhs) noexcept
{
return *static_cast<const T*>(lhs) == *static_cast<const T*>(rhs);
}
template<typename T>
static size_t fnHash(const void* buffer) noexcept
{
return typename T::Hash{}(*static_cast<const T*>(buffer));
}
template<typename T>
static Slice<Id> fnOper(void* buffer) noexcept
{
return static_cast<T*>(buffer)->operands();
}
static constexpr FnCopy tableCopy[sizeof...(Ts)] = {&fnCopy<Ts>...};
static constexpr FnMove tableMove[sizeof...(Ts)] = {&fnMove<Ts>...};
static constexpr FnDtor tableDtor[sizeof...(Ts)] = {&fnDtor<Ts>...};
static constexpr FnPred tablePred[sizeof...(Ts)] = {&fnPred<Ts>...};
static constexpr FnHash tableHash[sizeof...(Ts)] = {&fnHash<Ts>...};
static constexpr FnOper tableOper[sizeof...(Ts)] = {&fnOper<Ts>...};
static constexpr int getIndexFromTag(const char* tag) noexcept
{
constexpr int N = sizeof...(Ts);
constexpr const char* is[N] = {Ts::tag...};
for (int i = 0; i < N; ++i)
if (is[i] == tag)
return i;
return -1;
}
public:
template<typename T>
Language(T&& t, std::enable_if_t<WithinDomain<T>::value>* = 0) noexcept
{
tag = std::decay_t<T>::tag;
new (&buffer) std::decay_t<T>(std::forward<T>(t));
}
Language(const Language& other) noexcept
{
tag = other.tag;
tableCopy[getIndexFromTag(tag)](&buffer, &other.buffer);
}
Language(Language&& other) noexcept
{
tag = other.tag;
tableMove[getIndexFromTag(tag)](&buffer, &other.buffer);
}
~Language() noexcept
{
tableDtor[getIndexFromTag(tag)](&buffer);
}
Language& operator=(const Language& other) noexcept
{
Language copy{other};
*this = static_cast<Language&&>(copy);
return *this;
}
Language& operator=(Language&& other) noexcept
{
if (this != &other)
{
tableDtor[getIndexFromTag(tag)](&buffer);
tag = other.tag;
tableMove[getIndexFromTag(tag)](&buffer, &other.buffer); // nothrow
}
return *this;
}
int index() const noexcept
{
return getIndexFromTag(tag);
}
/// You should never call this function with the intention of mutating the `Id`.
/// Reading is ok, but you should also never assume that these `Id`s are stable.
Slice<Id> operands() noexcept
{
return tableOper[getIndexFromTag(tag)](&buffer);
}
Slice<Id> operands() const noexcept
{
return const_cast<Language*>(this)->operands();
}
template<typename T>
const T* get() const noexcept
{
static_assert(WithinDomain<T>::value);
return tag == T::tag ? reinterpret_cast<const T*>(&buffer) : nullptr;
}
bool operator==(const Language& rhs) const noexcept
{
return tag == rhs.tag && tablePred[getIndexFromTag(tag)](&buffer, &rhs.buffer);
}
bool operator!=(const Language& rhs) const noexcept
{
return !(*this == rhs);
}
public:
struct Hash
{
size_t operator()(const Language& language) const
{
size_t seed = std::hash<const char*>{}(language.tag);
hashCombine(seed, tableHash[getIndexFromTag(language.tag)](&language.buffer));
return seed;
}
};
};
inline void hashCombine(size_t& seed, size_t hash)
{
// Golden Ratio constant used for better hash scattering
// See https://softwareengineering.stackexchange.com/a/402543
seed ^= hash + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}
template<typename T>
struct LanguageHash<T, std::void_t<decltype(std::hash<T>{}(std::declval<T>()))>>
{
size_t operator()(const T& t) const
{
return std::hash<T>{}(t);
}
};
template<typename T, size_t I>
struct LanguageHash<std::array<T, I>>
{
size_t operator()(const std::array<T, I>& array) const
{
size_t seed = 0;
for (const T& t : array)
hashCombine(seed, languageHash(t));
return seed;
}
};
template<typename T>
struct LanguageHash<std::vector<T>>
{
size_t operator()(const std::vector<T>& vector) const
{
size_t seed = 0;
for (const T& t : vector)
hashCombine(seed, languageHash(t));
return seed;
}
};
} // namespace Luau::EqSat