x86recomp

Static recompilation of x86 and x86-64 Windows games into native 64-bit programs: the scaffold that gets a game running natively while its code is replaced, piece by piece, with hand-written C++. A game's machine code is translated ahead of time into C++ and linked against a runtime that reimplements the parts of Windows and its middleware the game uses. There is no emulator, interpreter or Wine in the result, and no game code or data in this repository.

The game ports built on it and their status are on the project site.

What is here

• Lifter (tools/lifter, recomp_lift): decodes a PE with Zydis and emits C++ for every function, one basic block at a time, with exact x86 integer and flag semantics. Straight-line x87 code becomes guarded "runs" that keep the FPU register stack in locals. 32-bit and x64 images both lift; x64 code runs on the Win64 ABI against a fixed CPU model (AMD family 16h; SSE3 to SSE4.1, AVX and LZCNT so far).
• x87 model (src/runtime/x87.cpp): exact 80-bit x87 (precision and rounding control, status-word flags) on Berkeley SoftFloat with integer fast paths, tested bit for bit against a real x87.
• SSE and AVX (src/runtime/sse.cpp): the XMM/YMM registers and MXCSR, with SoftFloat lanes and x86 NaN rules, tested bit for bit against the CPU like the x87 model.
• Runtime (src/runtime): the guest address space (4 GiB for 32-bit guests), PE loading, threads, SEH and x64 unwinding, crash and hang reports.
• HLE (src/runtime/hle): Win32 (kernel32, user32, gdi32, advapi32, shfolder, ...) on POSIX and SDL3; optional modules for Miles Sound System (with EAX 1-3 on our own reverb, modelled on Creative hardware), Bink, DirectDraw 7/Direct3D 7 and OpenGL 1.x (on a fixed-function device: SDL_GPU on Vulkan or native Metal, or dxvk-native's Direct3D 9 as a reference), Direct3D 9 and D3DX 9 (in progress), DirectSound 8, DirectInput 8, XInput and dbghelp; for x64 guests the UCRT and MSVCP140 (in progress).
• Shader translators (src/runtime/hlsl, recomp_hlslc): D3DX 9's HLSL dialect and compiled Direct3D 9 shaders (shader models 1-3) to GLSL, for the programmable pipeline on SDL_GPU.
• Tools: Ghidra export scripts (tools/ghidra), a PE symbol dumper (tools/pe_symbols.py), dev-time reference checks (tools/layout, tools/undname), and EAX reference measurement (tools/eax_capture: a Windows 98 recorder for Creative hardware, the same cases rendered by the runtime, and their comparison).

Consoles whose CPU the lifter already models are to be platform modules on the same core rather than forks: the first, for the PlayStation 4 (its executable format, system libraries and GPU), is in progress on its own branch.

ARCHITECTURE.md describes the design; docs/ the observed behaviour of the middleware reimplemented here (docs/miles.md).

Using it from a game project

set(X86RECOMP_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../x86recomp" CACHE PATH "")
set(CMAKE_LINK_DEPENDS_NO_SHARED ON)  # no relink when only a library changes
enable_testing()
add_subdirectory("${X86RECOMP_DIR}" x86recomp)

recomp_add_lifted(mygame_lifted "${CMAKE_CURRENT_SOURCE_DIR}/generated")
add_executable(mygame src/main.cpp $<TARGET_OBJECTS:mygame_lifted>)
target_link_libraries(mygame PRIVATE recomp_runtime recomp_mss32)

main() fills a recomp::GameConfig (id, guest install directory, EXE name, registry seed, optional hooks) and calls recomp::RunProcess. The lifter runs as a separate step over the user's own EXE:

recomp_lift --exe game.exe --symbols symbols --out generated \
  --manifest lifter.manifest

DLLs the game loads itself are lifted in the same run (--module game.dll --symbols dir [--manifest file], repeated) and listed in GameConfig::lifted_dlls.

Requirements

Linux x86-64, or macOS on Apple Silicon. Clang and LLVM (the static libLLVMDemangle.a for dbghelp), CMake 3.25+, Ninja, SDL3 (3.2+ for SDL_GPU); ffmpeg for Miles/Bink; glslang (glslangValidator) for the shaders, and on macOS SPIRV-Cross (spirv-cross) too. Graphics (D3D7 and OpenGL) use SDL_GPU: Vulkan on Linux, native Metal on macOS. On Linux a dxvk-native build (Direct3D 9 only, SDL3 window system) is optional: it adds the d3d9 backend (<ID>_GFX=d3d9), the reference image for SDL_GPU.

On macOS with Homebrew (brew install cmake ninja sdl3 ffmpeg llvm@22 glslang spirv-cross):

cmake --preset debug -DRECOMP_LLVM_ROOT=/opt/homebrew/opt/llvm@22

Licence

MIT (see LICENSE). Dependencies keep their own licences: Berkeley SoftFloat 3e (BSD-3-Clause) and Zydis (MIT) are fetched at build time; SDL3 (zlib), DXVK (zlib), ffmpeg (LGPL, linked dynamically) and LLVM's demangler (Apache-2.0 with LLVM exception) come from your system.