A high-performance LoongArch userspace emulator library designed for embedding and scripting applications.
Built on the proven architecture of libriscv, libloong has competitive interpreter performance while maintaining a compact ~18k line codebase.
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- Fast LoongArch interpreter with optional JIT
- Ultra-low latency call overheads
- Support for 64-bit LoongArch (LA64)
- Support for vector LSX and LASX instructions
- C++ API with Rust and Go bindings
- Zero dependencies
- Execution timeout and memory safety
- First-class pause/resume support
Game engine scripting is where libloong excels. Traditional games expose modding through shared libraries (full system access), embedded VMs like Lua (~150ns call overhead), or Java run-times. libloong has ~4ns call overhead.
See the example Asteroid game.
CMake configuration options:
LA_DEBUG=ON/OFF- Enable debug output (default: OFF)LA_BINARY_TRANSLATION=ON/OFF- Enable binary translation (default: OFF)LA_THREADED=ON/OFF- Enable threaded bytecode dispatch (default: ON)LA_MASKED_MEMORY_BITS=N- Set masked memory arena size to 2^N bytes (0 = disabled, default: 0)
Example with options:
cmake .. -DCMAKE_BUILD_TYPE=Release \
-DLA_MASKED_MEMORY_BITS=32 \
-DLA_BINARY_TRANSLATION=ON
make -j6#include <libloong/machine.hpp>
int main() {
// Load a LoongArch ELF binary
std::vector<uint8_t> binary = load_file("program.elf");
// Create a machine with 64MB memory
loongarch::Machine machine { binary, {
.memory_max = 64 * 1024 * 1024
}};
// Setup program arguments
machine.setup_linux({"program"}, {"LC_ALL=C"});
// Run the program
machine.simulate();
}STREAM memory benchmark:
Function Best Rate MB/s Avg time Min time Max time
Copy: 33146.7 0.004884 0.004827 0.004962
Scale: 27825.2 0.005792 0.005750 0.005920
Add: 31388.6 0.007712 0.007646 0.007797
Triad: 29250.7 0.008268 0.008205 0.008379There is a also a STREAM-like benchmark written in Rust in the examples:
Fill 76.3 MiB rate 27.9 GB/s | time min 2.9ms avg 3.1ms max 3.3ms
Copy 153 MiB rate 35.3 GB/s | time min 4.5ms avg 4.6ms max 5.0ms
Scale 153 MiB rate 23.0 GB/s | time min 7.0ms avg 7.0ms max 7.1ms
Add 229 MiB rate 31.9 GB/s | time min 7.5ms avg 7.6ms max 7.7ms
Triad 229 MiB rate 11.1 GB/s | time min 21.5ms avg 21.6ms max 21.8ms
Register machines still stand strongest at the end of 2025. libloong is currently the fastest 64-bit interpreter, reliably reaching 3000+ CoreMark score.
The lightweight JIT reaches 38% of native performance (15.5k vs 41k CoreMark) with full feature parity to the interpreter:
CoreMark 1.0 : 15580.375613 / GCC14.2.0 -O3 -DPERFORMANCE_RUN=1 / Static
Using embedded binary translation, it's currently possible to reach ~77% of native:
CoreMark 1.0 : 31962.238533 / GCC14.2.0 -O3 -DPERFORMANCE_RUN=1 / Static
.. however more work is needed to reach full potential. The upper bound for embedded binary translation should be around ~90% of native.