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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi Evan,<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'>Thanks a lot for the information!<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'>It’s a viable solution to write my own JITMemoryManager,
however I noticed that the JIT doesn’t know the length of the binary
function before it is actually emitted. This is a bit inconvenient especially
since I have to generate new functions at irregular times. I’m not too
keen on using the non-standard _expand function to resize memory to the right
size.<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'>Anyway, I also noticed that it’s also possible to do the
following:<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 style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'>executionEngine->removeModuleProvider(moduleProvider);<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:blue'>delete</span><span style='font-size:10.0pt;
font-family:"Courier New"'> moduleProvider;<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'>module->dropAllReferences();<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New";
color:blue'>delete</span><span style='font-size:10.0pt;font-family:"Courier New"'>
module;</span><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'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>This way the memory overhead of the IR of the function is removed
and the executionEngine stays around for further use and still manages the memory
of the binary functions.<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'>So is this a sane approach?<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'>Kind regards,<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'>Nicolas<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'><o:p> </o:p></span></p>
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<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"'>
llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu] <b>On Behalf
Of </b>Evan Cheng<br>
<b>Sent:</b> Wednesday, 21 May, 2008 20:16<br>
<b>To:</b> LLVM Developers Mailing List<br>
<b>Subject:</b> Re: [LLVMdev] Deleting order and acquiring generated function<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>When JITEmitter is teared down, it also deletes the
JITMemoryManager instance. That in turns release the memory of the generated
functions. Is this what you are referring to?<o:p></o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
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<div>
<p class=MsoNormal>The DefaultJITMemoryManager is pretty simple. You can
obviously write your own memory manager class that maps the memory in a way
that's persistent. Then all you have to do is to pass a handle of it to
JITEmitter.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Evan<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<div>
<p class=MsoNormal>On May 21, 2008, at 2:48 AM, Nicolas Capens wrote:<o:p></o:p></p>
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<p class=MsoNormal><br>
<br>
<o:p></o:p></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Hi all,<o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>I’m using LLVM to generate a fairly large number of separate
functions at run-time. To minimize the memory overhead, I’d like to
delete the IR and everything else that is no longer needed after a function has
been generated (I don’t use lazy compilation or anything like that).<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>I noticed that deleting the ExecutionEngine deletes everything
(Module, Function(s), ExistingModuleProvider, and even the LLVMBuilder).
Unfortunately it also frees the generated function in memory itself.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>So is there an existing way to delete everything except the
in-memory generated function? Alternatively, is there a way to just delete the
IR and related overhead so everything is ready for generating the next function?<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>If both are possible, which is the best approach? I have to
generate new functions from time to time, so keeping some of the LLVM objects
around seems like a good idea if the cost of reconstructing them is
considerable. As far as I can tell LLVM looks relatively light-weight though so
I’d prefer deleting everything and keeping just the generated functions…<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Thanks again for any info,<o:p></o:p></span></p>
</div>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Nicolas Capens<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif";
color:black'>_______________________________________________<br>
LLVM Developers mailing list<br>
<a href="mailto:LLVMdev@cs.uiuc.edu">LLVMdev@cs.uiuc.edu</a>
<a
href="http://llvm.cs.uiuc.edu">http://llvm.cs.uiuc.edu</a><br>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</a><o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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