[LLVMdev] LLVM JIT Questions

[Eli Bendersky]

On Tue, Apr 23, 2013 at 11:26 AM, Kaylor, Andrew <andrew.kaylor at intel.com>wrote:

>  Yes, exactly.  My patch adds a new ObjectCache class which can be
> registered with MCJIT.  MCJIT will then call this component before
> attempting to generate code to see if it has a cached object image for a
> given module.  If the ObjectCache has a cached object, MCJIT will skip the
> code generation step and just perform linking and loading.  If the
> ObjectCache does not have a cached version MCJIT will generate code as
> usual and then pass the generated object image to the ObjectCache to be
> cached before MCJIT performs its linking and loading.****
>
> ** **
>
> The ObjectCache is going to be offered as an abstract base class only.
> Clients will need to implement their own mechanism for identifying modules
> and storing cached images, though I do have a unit test which provides a
> very simple reference implementation.****
>
> ** **
>
> This mechanism is not coupled directly with the ELF format.  It will work
> with MachO objects as well, to the extent that MachO is supported by MCJIT.
>

That sounds like a good approach.

Eli















> -Andy
>
> **
>
>
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
> Behalf Of Dmitri Rubinstein
> Sent: Tuesday, April 23, 2013 5:25 AM
> To: LLVM Dev
> Subject: [LLVMdev] LLVM JIT Questions
>
> Hi all,
>
> For my current project I need a couple of informations about JIT. I seen
> similar questions already, but the answers are a bit older and I hope
> somebody can provide me a recent information.
>
> 1. In my project I frequently construct LLVM IR, compile it and execute
> with JIT. Because the constructed IR is often the same (but can vary
> depending on input data) I would like to cache produced machine code on the
> disk. There is no JIT API for dumping and loading of compiled code.
>
> Are there any plans to add this feature in the near future ?
>
> How complex would it be to implement this for somebody who has only
> experience with LLVM code generation, but no deep knowledge of JIT
> internals ?
>
> 2. I also need to interface with C-libraries which are either loaded as a
> shared library or pre-compiled with clang and loaded as BC file.
> However, LLVM does not provide a way how to construct function signature
> compatible with the C-ABI of the specific platform. I know that clang
> library has internally this information, but I need this functionality
> without clang.
>
> Is there any documentation which describes how to do generate C-ABI
> compatible LLVM functions or code that implements this functionality ?
>
> Thanks,
>
> Dmitri
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