FEX-Emu--FEX/ThunkLibs/Generator/data_layout.h

#pragma once

#include "analysis.h"

#include <clang/Frontend/FrontendAction.h>

#include <cstdint>
#include <optional>
#include <string>
#include <unordered_map>
#include <variant>
#include <vector>

struct SimpleTypeInfo {
  uint64_t size_bits;
  uint64_t alignment_bits;

  bool operator==(const SimpleTypeInfo& other) const {
    return size_bits == other.size_bits && alignment_bits == other.alignment_bits;
  }
};

struct StructInfo : SimpleTypeInfo {
  struct MemberInfo {
    uint64_t size_bits; // size of this member. For arrays, total size of all elements
    uint64_t offset_bits;
    std::string type_name;
    std::string member_name;
    std::optional<uint64_t> array_size;
    bool is_function_pointer;
    bool is_integral;
    bool is_signed_integer;

    bool operator==(const MemberInfo& other) const {
      return size_bits == other.size_bits && offset_bits == other.offset_bits &&
             // The type name may differ for integral types if all other parameters are equal
             (type_name == other.type_name || (is_integral && other.is_integral)) && member_name == other.member_name &&
             array_size == other.array_size && is_function_pointer == other.is_function_pointer && is_integral == other.is_integral;
    }
  };

  std::vector<MemberInfo> members;

  bool operator==(const StructInfo& other) const {
    return (const SimpleTypeInfo&)*this == (const SimpleTypeInfo&)other &&
           std::equal(members.begin(), members.end(), other.members.begin(), other.members.end());
  }
};

struct TypeInfo : std::variant<std::monostate, SimpleTypeInfo, StructInfo> {
  using Parent = std::variant<std::monostate, SimpleTypeInfo, StructInfo>;

  TypeInfo() = default;
  TypeInfo(const SimpleTypeInfo& info)
    : Parent(info) {}
  TypeInfo(const StructInfo& info)
    : Parent(info) {}

  // Opaque declaration with no full definition.
  // Pointers to these can still be passed along ABI boundaries assuming
  // implementation details are only ever accessed on one side.
  bool is_opaque() const {
    return std::holds_alternative<std::monostate>(*this);
  }

  const StructInfo* get_if_struct() const {
    return std::get_if<StructInfo>(this);
  }

  StructInfo* get_if_struct() {
    return std::get_if<StructInfo>(this);
  }

  const SimpleTypeInfo* get_if_simple_or_struct() const {
    auto as_struct = std::get_if<StructInfo>(this);
    if (as_struct) {
      return as_struct;
    }
    return std::get_if<SimpleTypeInfo>(this);
  }
};

struct FuncPtrInfo {
  std::array<uint8_t, 32> sha256;
  std::string result;
  std::vector<std::string> args;
};

struct ABI : std::unordered_map<std::string, TypeInfo> {
  std::unordered_map<std::string, FuncPtrInfo> thunked_funcptrs;
  int pointer_size; // in bytes
};

std::unordered_map<const clang::Type*, TypeInfo>
ComputeDataLayout(const clang::ASTContext& context, const std::unordered_map<const clang::Type*, AnalysisAction::RepackedType>& types);

// Convert the output of ComputeDataLayout to a format that isn't tied to a libclang session.
// As a consequence, type information is indexed by type name instead of clang::Type.
ABI GetStableLayout(const clang::ASTContext& context, const std::unordered_map<const clang::Type*, TypeInfo>& data_layout);

/**
 * Returns the type of the given name, but replaces any mentions of integer
 * types with fixed-size equivalents.
 *
 * Examples:
 * - int -> int32_t
 * - unsigned long long* -> uint64_t*
 * - MyStruct -> MyStruct (no change)
 */
std::string GetTypeNameWithFixedSizeIntegers(clang::ASTContext&, clang::QualType);

enum class TypeCompatibility {
  Full,       // Type has matching data layout across architectures
  Repackable, // Type has different data layout but can be repacked automatically
  None,       // Type has different data layout and cannot be repacked automatically
};

class DataLayoutCompareAction : public AnalysisAction {
public:
  DataLayoutCompareAction(const ABI& guest_abi)
    : guest_abi(guest_abi) {}

  TypeCompatibility GetTypeCompatibility(const clang::ASTContext&, const clang::Type*,
                                         const std::unordered_map<const clang::Type*, TypeInfo> host_abi,
                                         std::unordered_map<const clang::Type*, TypeCompatibility>& type_compat);

  FuncPtrInfo LookupGuestFuncPtrInfo(const char* funcptr_id);

protected:
  const ABI& guest_abi;
};