<div dir="ltr"><br><div class="gmail_quote">---------- Forwarded message ----------<br>From: <b class="gmail_sendername">Aliaksei Zasenka</b> <span dir="ltr"><<a href="mailto:listhex@gmail.com">listhex@gmail.com</a>></span><br>Date: 2014-10-29 0:54 GMT+02:00<br>Subject: Re: [LLVMdev] MCJIT + Win64 SEH handling problem (missing unwinding info)<br>To: "Kaylor, Andrew" <<a href="mailto:andrew.kaylor@intel.com">andrew.kaylor@intel.com</a>><br><br><br><div dir="ltr"><div><div>Andrew,<br><br></div>First of all thanks for your answer. <br><br>In general I understand what steps should be done. Firstly something like RyntimeDyldCOFF should be implemented and supported. This class is responsible for object file loading, resolving relocations and EH frames registration. Then FunctionTable and unwind data located in COFF should be introduced to system with RtlAddFunctionTable on finalizing. <br><br></div><div>I suppose lots of details may arise and to make quality product is not that simple like it seems. But <span lang="en"><span>I think</span> <span>I'll try</span> <span>to make a</span> <span>prototype. <br></span></span><br><span lang="en"><span>Would appreciate any help or advice.</span></span></div><div><br><br></div><div>Regards,<br>Aliaksei<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2014-10-28 22:37 GMT+02:00 Kaylor, Andrew <span dir="ltr"><<a href="mailto:andrew.kaylor@intel.com" target="_blank">andrew.kaylor@intel.com</a>></span>:<div><div class="h5"><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi Aliaksei,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The MCJIT code is structured in such a way as to abstract the details of object file formats. What is primarily lacking is a COFF implementation of the RuntimeDyld
interface. When we first implemented MCJIT on Windows using the ELF object format was sufficient for the applications we were aware of that intended to use MCJIT on Windows, so we used ELF-on-Windows as a sort of shortcut.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I’m not aware of anything that would prevent MCJIT from working with COFF files if someone was willing to invest the effort to implement the RuntimeDyld support
for COFF. It’s likely that one or two small issues would arise, but I don’t think there would be any major design issues. However, even after basic MCJIT execution of COFF images is in place there may be additional work to be done to make exception handling
work correctly. I don’t know one way or the other about that.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If you are interested in trying to implement the RuntimeDyld support for COFF I can provide you with some details of what is involved.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">-Andy<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></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""> <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>]
<b>On Behalf Of </b>Aliaksei Zasenka<br>
<b>Sent:</b> Tuesday, October 28, 2014 5:26 AM<br>
<b>To:</b> <a href="mailto:LLVMdev@cs.uiuc.edu" target="_blank">LLVMdev@cs.uiuc.edu</a><br>
<b>Subject:</b> [LLVMdev] MCJIT + Win64 SEH handling problem (missing unwinding info)<u></u><u></u></span></p><div><div>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Hi all,<u></u><u></u></p>
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I'm using MCJIT for running the manually generated code under both Win32 and Win64 environments. Unfortunately catching exceptions under Win64 doesn't work. As I understand the main problem is the lack of function table that is needed to unwind a call stack.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Microsoft <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/ms680595%28v=vs.85%29.aspx" target="_blank">
says </a><br>
<i>Function tables are used on 64-bit Windows to determine how to unwind or walk the stack. These tables are usually generated by the compiler and stored as part of the image. However, applications must provide the function table for dynamically generated code.</i><u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">As I can see LLVM usually creates Function Table when generating COFF (Win64EH::UnwindEmitter). But MCJIT can load only ELF files.
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Is there any way to workaround the problem? Maybe it is already planned to implement COFF loading in MCJIT?<u></u><u></u></p>
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<p class="MsoNormal">Best regards,<br>
Aliaksei<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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