LLI (LLVM Interpreter) is a command-line tool that allows users to directly execute programs compiled into LLVM bitcode format. It is a part of the LLVM (Low-Level Virtual Machine) compiler infrastructure and provides a convenient way to run programs without the need for traditional compilation and linking steps.
Key features and functionalities of LLI include:
- Execution of LLVM Bitcode: LLI is designed to execute programs that have been compiled into LLVM bitcode, which is an intermediate representation of code generated by LLVM compilers. Bitcode is platform-independent and can be executed by LLI on any system with LLVM support, making it a versatile tool for running programs across different platforms.
- Just-In-Time (JIT) Compilation: LLI supports Just-In-Time (JIT) compilation, allowing it to dynamically compile and execute LLVM bitcode on-the-fly. This enables rapid execution of programs without the need for separate compilation and linking steps, making it particularly useful for development and debugging purposes.
- Interactive Mode: LLI provides an interactive mode that allows users to execute LLVM bitcode interactively from the command line. Users can input LLVM bitcode expressions or commands directly into the LLI prompt, enabling quick experimentation and testing of code snippets without the need to write separate source files.
- Support for LLVM Toolchain: LLI seamlessly integrates with other components of the LLVM toolchain, such as LLVM IR (Intermediate Representation) generators and optimizers. It can be used in conjunction with LLVM compilers, such as Clang, to execute programs directly from LLVM IR or LLVM bitcode files generated during the compilation process.
- Debugging and Profiling: LLI supports debugging and profiling features that allow users to analyze the execution of LLVM bitcode programs. Users can enable debug symbols and instrumentation options to track program behavior, identify performance bottlenecks, and diagnose issues during execution.
- Cross-Platform Compatibility: LLI is cross-platform compatible and can be used on various operating systems, including Linux, macOS, and Windows. It leverages LLVM’s platform-independent design to ensure consistent behavior and performance across different environments.
- Documentation and Resources: The LLVM project provides comprehensive documentation and resources for LLI, including command-line options, usage examples, and troubleshooting guides. Developers can refer to the LLVM documentation website for detailed information on using LLI and optimizing LLVM bitcode for efficient execution.
lli Command Examples
1. Execute a bitcode or IR file:
# lli [path/to/file.ll]
2. Execute with command line arguments:
# lli [path/to/file.ll] [argument1 argument2 ...]
3. Enable all optimizations:
# lli -O3 [path/to/file.ll]
4. Load a dynamic library before linking:
# lli --dlopen=[path/to/library.dll] [path/to/file.ll]
Summary
In summary, LLI is a versatile tool for executing LLVM bitcode programs directly from the command line. With its support for JIT compilation, interactive mode, integration with the LLVM toolchain, debugging and profiling capabilities, and cross-platform compatibility, LLI offers a convenient and efficient way to run and test programs compiled into LLVM bitcode format.