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execution-engine.rst

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Execution engine

.. currentmodule:: llvmlite.binding

The execution engine is where actual code generation and execution happen. At present a single execution engine, MCJIT, is exposed.

Functions

  • .. function:: create_mcjit_compiler(module, target_machine)

   Create a MCJIT-powered engine from the given *module* and
   *target_machine*.

   * *module* does not need to contain any code.
   * Returns a :class:`ExecutionEngine` instance.



  • .. function:: check_jit_execution()

   Ensure that the system allows creation of executable memory
   ranges for JIT-compiled code. If some security mechanism
   such as SELinux prevents it, an exception is raised.
   Otherwise the function returns silently.

   Calling this function early can help diagnose system
   configuration issues, instead of letting JIT-compiled
   functions crash mysteriously.

The ExecutionEngine class

A wrapper around an LLVM execution engine. The following methods and properties are available:

  • .. method:: add_module(module)

   Add the *module*---a :class:`ModuleRef` instance---for
   code generation. When this method is called, ownership
   of the module is transferred to the execution engine.


  • .. method:: finalize_object()

   Make sure all modules owned by the execution engine are
   fully processed and usable for execution.


  • .. method:: get_function_address(name)

   Return the address of the function *name* as an integer.
   It's a fatal error in LLVM if the symbol of *name* doesn't exist.


  • .. method:: get_global_value_address(name)

   Return the address of the global value *name* as an
   integer.
   It's a fatal error in LLVM if the symbol of *name* doesn't exist.


  • .. method:: remove_module(module)

   Remove the *module*---a :class:`ModuleRef` instance---from
   the modules owned by the execution engine. This allows
   releasing the resources owned by the module without
   destroying the execution engine.


  • .. method:: add_object_file(object_file)

  Add the symbols from the specified object file to the execution
  engine.

  * *object_file* str or :class:`ObjectFileRef`: a path to the object file
      or a object file instance. Object file instance is not usable after this
      call.


  • .. method:: set_object_cache(notify_func=None, getbuffer_func=None)

   Set the object cache callbacks for this engine.

   * *notify_func*, if given, is called whenever the engine
     has finished compiling a module. It is passed the
     ``(module, buffer)`` arguments:

     * *module* is a :class:`ModuleRef` instance.
     * *buffer* is a bytes object of the code generated for
       the module.

     The return value is ignored.

   * *getbuffer_func*, if given, is called before the engine
     starts compiling a module. It is passed an argument,
     *module*, a :class:`ModuleRef` instance of the module
     being compiled.

     * It can return ``None``, in which case the module
       is compiled normally.
     * It can return a bytes object of native code for the
       module, which bypasses compilation entirely.


  • .. attribute:: target_data

   The :class:`TargetData` used by the execution engine.