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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’d be OK with disabled these tests if they can be specifically disabled for ARM with clang.<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 main purpose of these tests is to ensure that none of the MCJIT/RuntimeDyld/*MemoryManager layering gets rearranged in a way that makes remote execution
impossible.<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">I would also note that the failure isn’t actually in anything MCJIT-specific. Aside from the fact that it seems to be clang-specific, the code that is failing
is specific to the lli remote implementation. It’s not clear to me why it would fail under aggressive optimization with clang, but I wouldn’t characterize that code as particularly robust.<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">I just updated the bugzilla report with a few comments about the failure. The short of it is that there’s nothing MCJIT-specific about this failure. It’s
most likely a pipe I/O problem. I think it’s possible that the clang optimizations are just exposing a timing-related vulnerability in the pipe handling.<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""> Renato Golin [mailto:renato.golin@linaro.org]
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<b>Sent:</b> Tuesday, November 26, 2013 1:30 AM<br>
<b>To:</b> NAKAMURA Takumi<br>
<b>Cc:</b> Kaylor, Andrew; LLVM Dev<br>
<b>Subject:</b> Re: MCJIT RemoteMemoryManager Failures on ARM<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 26 November 2013 01:55, NAKAMURA Takumi <<a href="mailto:geek4civic@gmail.com" target="_blank">geek4civic@gmail.com</a>> wrote:<o:p></o:p></p>
<p class="MsoNormal">IMHO, tests may be suppressed with lit.local.cfg, only if;<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">They were disabled, but then re-enabled because they don't fail on normal build bots, but they do on self-host bots. So, I think this is a more serious issue than just MCJIT, I think this is a Clang miscompilation. I'll try on x86 to see
if the self-hosting problem appears.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> - The issue is filed -- PR18057<br>
- There is at least one person responsible to watch on this issue.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Yes, but without priority, the bug will be forgotten.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I would not help you since I don't have any arm boxes.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I have an ARM box which you can SSH into, if you need. My knowledge of how the MCJIT should behave is very limited. If you're willing to take a look, I'd do my best to help you working on ARM.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">cheers,<o:p></o:p></p>
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<p class="MsoNormal">--renato<o:p></o:p></p>
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