[lldb-dev] Load object file on the fly

[Carlo Kok via lldb-dev]

On 2017-02-28 18:36, Greg Clayton wrote:
>
>> On Feb 28, 2017, at 4:19 AM, Carlo Kok via lldb-dev
>> <lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>> wrote:
>>
>> As far as I can tell from reading the source LLDB has facilities to
>> load a "jitted" clang fragment as an object file, load it into the
>> target process "run" it and unload it. Could this process be reused
>> externally? Say from the SB or lower level apis?
>>
>> What I want to accomplish is allow better expression evaluation for my
>> own languages by compling a piece of code to an object file (coff/elf,
>> whatever), passing all locals/args as arguments to this and getting
>> the evaluated result out of it. Is something like this possible?
>
> Yes. In SBProcess you can load a shared library and unload it:
>
>   //------------------------------------------------------------------
>   /// Load a shared library into this process.
>   ///
>   /// @param[in] remote_image_spec
>   ///     The path for the shared library on the target what you want
>   ///     to load.
>   ///
>   /// @param[out] error
>   ///     An error object that gets filled in with any errors that
>   ///     might occur when trying to load the shared library.
>   ///
>   /// @return
>   ///     A token that represents the shared library that can be
>   ///     later used to unload the shared library. A value of
>   ///     LLDB_INVALID_IMAGE_TOKEN will be returned if the shared
>   ///     library can't be opened.
>   //------------------------------------------------------------------
>   uint32_tLoadImage(lldb::SBFileSpec&remote_image_spec,
> lldb::SBError&error);
>
>   //------------------------------------------------------------------
>   /// Load a shared library into this process.
>   ///
>   /// @param[in] local_image_spec
>   ///     The file spec that points to the shared library that you
>   ///     want to load if the library is located on the host. The
>   ///     library will be copied over to the location specified by
>   ///     remote_image_spec or into the current working directory with
>   ///     the same filename if the remote_image_spec isn't specified.
>   ///
>   /// @param[in] remote_image_spec
>   ///     If local_image_spec is specified then the location where the
>   ///     library should be copied over from the host. If
>   ///     local_image_spec isn't specified, then the path for the
>   ///     shared library on the target what you want to load.
>   ///
>   /// @param[out] error
>   ///     An error object that gets filled in with any errors that
>   ///     might occur when trying to load the shared library.
>   ///
>   /// @return
>   ///     A token that represents the shared library that can be
>   ///     later used to unload the shared library. A value of
>   ///     LLDB_INVALID_IMAGE_TOKEN will be returned if the shared
>   ///     library can't be opened.
>   //------------------------------------------------------------------
>   uint32_tLoadImage(constlldb::SBFileSpec&local_image_spec,
>                      constlldb::SBFileSpec&remote_image_spec,
>                      lldb::SBError&error);
>
>   lldb::SBErrorUnloadImage(uint32_timage_token);
>

Does that work with (non shared, not linked) object files too? Because 
SO's have different visibility rules (And on windows they work 
completely different with exports/imports) which will probably interfere 
with using it as underlying logic for evaluating?

-- 
Carlo Kok
RemObjects Software