This is an experimental project that modifies Apple's Rosetta technology to use less precise but significantly faster x87 instruction handlers. The benchmarks show approximately 4-5x performance improvement for x87 floating-point operations.
- macOS 15.5 or compatible
- C compiler (clang)
- CMake
- Administrator privileges (for running helper service)
cmake -B build
cmake --build build
clang -v -arch x86_64 -mno-sse -mfpmath=387 ./sample/math.c -o ./build/math
This requires two terminal windows:
-
Run the helper service as root from the build folder:
sudo ./rosettax87 -
Run the target program from the build folder:
./rosettax87 ./math
╰─$ ./math
benchmark run_fsqrt
Result: 40800000
Run 1 time: 246664 ticks
Result: 40800000
Run 2 time: 233811 ticks
Result: 40800000
Run 3 time: 227264 ticks
Result: 40800000
Run 4 time: 225907 ticks
Result: 40800000
Run 5 time: 228230 ticks
Result: 40800000
Run 6 time: 227629 ticks
Result: 40800000
Run 7 time: 226741 ticks
Result: 40800000
Run 8 time: 227249 ticks
Result: 40800000
Run 9 time: 227047 ticks
Result: 40800000
Run 10 time: 226771 ticks
Average time: 229731 ticks
╰─$ ./rosettax87 ./math
launching into program
RosettaRuntimex87 built Apr 23 2025 18:43:47
benchmark run_fsqrt
Result: 40800000
Run 1 time: 48682 ticks
Result: 40800000
Run 2 time: 48292 ticks
Result: 40800000
Run 3 time: 48306 ticks
Result: 40800000
Run 4 time: 48369 ticks
Result: 40800000
Run 5 time: 48230 ticks
Result: 40800000
Run 6 time: 48561 ticks
Result: 40800000
Run 7 time: 49638 ticks
Result: 40800000
Run 8 time: 48371 ticks
Result: 40800000
Run 9 time: 48313 ticks
Result: 40800000
Run 10 time: 48410 ticks
Average time: 48517 ticks
If you want to examine runtime and libRosettaRuntime using IDA PRO, you need to use chain_fixup.py.
libRosettaRuntimeis located at/Library/Apple/usr/libexec/oah/libRosettaRuntime.runtimeis located at/usr/libexec/rosetta/runtime.
You can use the brew wine@devel cask with RosettaHack x87. It supports launching Windows applications through Wine with an environment variable ROSETTA_X87_PATH.
- Install
wine@develusing Homebrew
brew install --cask wine@devel- To permanently set the environment variable, add the following to your
~/.bashrcor~/.zshrcfile:
export ROSETTA_X87_PATH=/Path/To/rosettax87- Run rosettax87 as sudo in a separate terminal
sudo $ROSETTA_X87_PATH- Run the Windows application
wine PATH_TO_BINARY.exeThis project is licensed under MIT.