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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Yes, at some point we definitely should introduce stubs as a last resort for x86-64 relocations when the sections are too far apart, but I’d like to avoid it
whenever possible.<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">What I meant in my previous message was that I’d have RecordingMemoryManager use something other than malloc (such as the memory API used by SectionMemoryManager)
to keep section near one another.<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""> Alexey Samsonov [mailto:samsonov@google.com]
<br>
<b>Sent:</b> Wednesday, January 30, 2013 3:59 AM<br>
<b>To:</b> Kaylor, Andrew<br>
<b>Cc:</b> LLVM Developers Mailing List<br>
<b>Subject:</b> Re: Assertions in RuntimeDyldELF in ExecutionEngine/MCJIT tests<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Andrew,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Looks like RecordingMemoryManager in lli just calls malloc() and it would be strange to make assumptions (or enforce) that the difference between two returned pointers in 64-bit<o:p></o:p></p>
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<p class="MsoNormal">virtual address space will be fit into 32 bits. Can we do smth similar to what Adhemerval proposed (see the special case in processRelocationRef for ELF::R_PPC64_REL24 relocations)?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Jan 29, 2013 at 9:40 PM, Kaylor, Andrew <<a href="mailto:andrew.kaylor@intel.com" target="_blank">andrew.kaylor@intel.com</a>> wrote:<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">Hi Alexey,</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">I think the most likely way to resolve this is to have the RecordingMemoryManager do something more
complex to manage its allocations in such a way as to guarantee that they are all within proximity of one another. The code that is asserting is handling a relocation where code was generated to use a 32-bit relative offset in 64-bit code. If the two sections
involved really are more than a 32-bit offset apart then the generated code will not work.</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">Alternatively, we could have MCJIT use whatever code generation option will prevent 32-bit relative
relocations from being generated in the first place. That would probably be preferable, but I haven’t had success trying to do that in limited efforts up to now.</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">As it happens, I’m working with the ‘-use-remote’ option for lli this week trying to add support
for actual out-of-process execution. As I do, I’ll take a look at the allocation scheme in RecordingMemoryManager and see if there is something reasonable I can do there.</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">In the meantime, is there any way that you can mark these tests as XFAIL in the sanitizer case?</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">Thanks,</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>
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<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""> Alexey Samsonov [mailto:<a href="mailto:samsonov@google.com" target="_blank">samsonov@google.com</a>]
<br>
<b>Sent:</b> Tuesday, January 29, 2013 3:36 AM<br>
<b>To:</b> LLVM Developers Mailing List<br>
<b>Cc:</b> Kaylor, Andrew<br>
<b>Subject:</b> Assertions in RuntimeDyldELF in ExecutionEngine/MCJIT tests</span><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">Hi!<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'm trying to run LLVM test suite under AddressSanitizer and get test failures in:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> LLVM :: ExecutionEngine/MCJIT/simpletest-remote.ll<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> LLVM :: ExecutionEngine/MCJIT/test-data-align-remote.ll<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> LLVM :: ExecutionEngine/MCJIT/test-fp-no-external-funcs-remote.ll<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> LLVM :: ExecutionEngine/MCJIT/test-global-init-nonzero-remote.ll<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">All of them fail with assertion:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">lli: /usr/local/google/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp:230: void llvm::RuntimeDyldELF::resolveX86_64Relocation(const llvm::SectionEntry &, uint64_t, uint64_t,
uint32_t, int64_t): Assertion `RealOffset <= (2147483647) && RealOffset >= (-2147483647-1)' failed.<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">The reason is that AddressSanitizer replaces system malloc with its own allocator, which<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">allocates memory at "unusual" parts of heap and the difference between pointers can be significant<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">(and doesn't fit in 32 bytes).<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 add debug output to calculation of RealOffset in resolveX86_64Relocation:<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"> uint64_t FinalAddress = Section.LoadAddress + Offset;<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> fprintf(stderr, "%x + %lx + %lx - %lx = %lx\n",<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> *Placeholder, Value, Addend, FinalAddress, RealOffset);<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);<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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<pre style="line-height:13.5pt;white-space:pre-wrap"> <o:p></o:p></pre>
<pre style="line-height:13.5pt"><span style="font-family:"Arial","sans-serif";color:#222222">This is what I get for system malloc:</span><o:p></o:p></pre>
<pre style="line-height:13.5pt;white-space:pre-wrap"> <o:p></o:p></pre>
<pre style="line-height:13.5pt">0 + 7fec9867a000 + 0 - 7fec9867a040 = ffffffffffffffc0<o:p></o:p></pre>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">This is what I get for ASan allocator (which results in assert failure):<o:p></o:p></p>
<pre style="line-height:13.5pt;white-space:pre-wrap"> <o:p></o:p></pre>
<pre style="line-height:13.5pt">0 + 600c0000a8a0 + 0 - 6018000090a0 = fffffff400001800<o:p></o:p></pre>
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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">Alexey Samsonov, MSK<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br clear="all">
<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">Alexey Samsonov, MSK<o:p></o:p></p>
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