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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Yes, MCJIT works on Windows (though it generates ELF object images).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The primary differences between MCJIT and JIT have to do with the way that they work. MCJIT does not support lazy compilation of functions as JIT does because
MCJIT works at the Module level rather than the Function level. You can work around this limitation to some extent by creating multiple smaller Modules. However, at the moment you need one instance of MCJIT per Module. We plan to address that, but right
now it is a limitation.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The object caching support is in place as of r180150.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Andy<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Dmitri Rubinstein [mailto:dmitri.rubinstein@googlemail.com]
<br>
<b>Sent:</b> Tuesday, April 23, 2013 4:38 PM<br>
<b>To:</b> Kaylor, Andrew<br>
<b>Cc:</b> Eli Bendersky; LLVM Dev<br>
<b>Subject:</b> RE: [LLVMdev] LLVM JIT Questions<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p>This sounds great, but will it work on Windows as well ?<o:p></o:p></p>
<p>I considered MCJIT for my work, but was not sure if there are any features supported by old JIT but missing in MCJIT.
<o:p></o:p></p>
<p>Thanks,<o:p></o:p></p>
<p>Dmitri<o:p></o:p></p>
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<p class="MsoNormal">Am 23.04.2013 20:26 schrieb "Kaylor, Andrew" <<a href="mailto:andrew.kaylor@intel.com">andrew.kaylor@intel.com</a>>:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Andy</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Eli Bendersky [mailto:<a href="mailto:eliben@google.com" target="_blank">eliben@google.com</a>]
<br>
<b>Sent:</b> Tuesday, April 23, 2013 11:13 AM<br>
<b>To:</b> Kaylor, Andrew<br>
<b>Cc:</b> Dmitri Rubinstein; LLVM Dev<br>
<b>Subject:</b> Re: [LLVMdev] LLVM JIT Questions</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Tue, Apr 23, 2013 at 10:39 AM, Kaylor, Andrew <<a href="mailto:andrew.kaylor@intel.com" target="_blank">andrew.kaylor@intel.com</a>> wrote:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt">Hi Dmitri,<br>
<br>
Regarding your first question, if you can use the MCJIT engine a caching mechanism will be available very soon. I'm preparing to commit a patch today to add this capability. I'm not sure what it would take to get something similar working with the older JIT
engine. I expect it would take a fair amount of work because the older JIT engine isn't designed around object loading as the MCJIT engine is.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I would expect it to be very hard to do with the old JIT, because it JITs the machine code in a "loaded" form (absolute addresses put into the needed places). This is tightly coupled
with the current execution and does not apply to other executions. MCJIT allows this by virtue of having a not-yet-loaded ELF object which can be cached for later use. I imagine this is what you do in your patch, Andy.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Eli<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Regarding your second question, there might be more than one way to do this, but once you have an llvm::Function (but before you JIT the code) you should be able to use llvm::Function::setCallingConv().<br>
<br>
-Andy<o:p></o:p></p>
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-----Original Message-----<br>
From: <a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">llvmdev-bounces@cs.uiuc.edu</a> [mailto:<a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">llvmdev-bounces@cs.uiuc.edu</a>] On Behalf Of Dmitri Rubinstein<br>
Sent: Tuesday, April 23, 2013 5:25 AM<br>
To: LLVM Dev<br>
Subject: [LLVMdev] LLVM JIT Questions<br>
<br>
Hi all,<br>
<br>
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.<br>
<br>
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.<br>
<br>
Are there any plans to add this feature in the near future ?<br>
<br>
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 ?<br>
<br>
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.<br>
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.<br>
<br>
Is there any documentation which describes how to do generate C-ABI compatible LLVM functions or code that implements this functionality ?<br>
<br>
Thanks,<br>
<br>
Dmitri<br>
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