[LLVMdev] Dynamically loading native code generated from LLVM IR

[Armin Steinhoff]

Daniel,

I didn't find the MCJIT directory under unitests/ExecutionEngine ... 
there is only a directory called JIT.
You mean this directory ?

Many thanks

--Armin



Malea, Daniel wrote:
> Take a look at the MCJIT unit tests under unittests/ExecutionEngine/MCJIT
>
> The MCJITTestBase class does the majority of the interactions with the LLVM API you're referring to.
>
> Good luck,
> Dan
>
> On 2012-10-13, at 4:57 AM, "Armin Steinhoff" <as at steinhoff-automation.com> wrote:
>
>> Kaylor,
>>
>> do you have some good documented example code which shows the usage of the MCJIT ?
>> This would help a lot ... the sematic of lots of API calls are not intuitively understandable.
>>
>> Best Regards
>>
>> --Armin
>>
>>
>>
>> Kaylor, Andrew wrote:
>>> I'm not sure I understand your use case, but MCJIT (as opposed to the legacy JIT) does almost exactly what you're asking for.  It generates an in-memory object file image (using addPassesToEmitMC) and then loads and links it for execution.
>>>
>>> If there's some particular detail you don't like in the way this is happening, you might be able to generate a file as you have and then use the RuntimeDyld interface to load it.  The llvm-rtdyld tool does something like this.
>>>
>>> -Andy
>>>
>>> -----Original Message-----
>>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Baris Aktemur
>>> Sent: Thursday, October 11, 2012 11:58 PM
>>> To: llvmdev at cs.uiuc.edu
>>> Subject: [LLVMdev] Dynamically loading native code generated from LLVM IR
>>>
>>> Hi,
>>>
>>> I'm building LLVM IR. I'd like to compile this IR to native code (I don't want JIT) and immediately load it to execute. So far, I've the following:
>>>
>>> 1) I can emit the IR to native assembly/object file doing the same thing llc does (using TargetMachine::addPassesToEmitFile).
>>> 2) I can dynamically load a precompiled .so file (using llvm::sys::DynamicLibrary::getPermanentLibrary), get a function pointer from that file, and execute.
>>>
>>> I can't dynamically load the .o file I produce in step 1 because it's a static library. If I could produce a .so file in step 1, my problem would be solved. llc has a "-relocation-model=pic" option, but the file produced with that did not dynamically load. I got lost in clang's options when trying to find where the "-shared" and "-fPIC" options are used.
>>>
>>> So, my question is: Which API should I look at to emit dynamically loadable native code from LLVM IR?
>>>
>>> I would also like to emit code to an in-memory stream instead of a file because everything happens at runtime, but that's a secondary concern.
>>>
>>> Thanks in advance.
>>>
>>> -Baris Aktemur
>>>
>>>
>>>
>>>
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