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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Intruction incorrectly marked as not mappable back to source code"
href="https://bugs.llvm.org/show_bug.cgi?id=47781">47781</a>
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<th>Summary</th>
<td>Intruction incorrectly marked as not mappable back to source code
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>10.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>DebugInfo
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
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<th>Reporter</th>
<td>wcohen@redhat.com
</td>
</tr>
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<th>CC</th>
<td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
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<div>
<pre>When reviewing the binaries of programs build with clang-10.0.1-2.fc32.x86_64
on fedora 32 with "eu-readelf --debug-dump=decodedline" I found that clang
appeared to incorrectly state that one of the instructions in the executable
could not be mapped back to the source code. This can be observed build a
small rpm package on Fedora 32.
Get the heapsort-0.5-fc32.src.rpm from
<a href="https://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps">https://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps</a> .
Then following the steps below to build the binary:
sudo dnf build-dep ./heapsort-0.5-fc32.src.rpm
rpm -Uvh heapsort-0.5-fc32.src.rpm
cd ~/rpmbuild/SPECS
export CC=clang
export CXX=clang++
rpmbuild --define '%optflags -O2 -g -pipe -Wall -Werror=format-security
-Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions
-fstack-protector-strong -grecord-gcc-switches
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
-specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
-fasynchronous-unwind-tables -fcf-protection -Wno-narrowing
-Wno-unused-command-line-argument' -bc heapsort.spec
The issue can be seen in the resulting heapsort binary:
cd ~/rpmbuild/BUILD/heapsort-0.5
eu-readelf --debug-dump=decodedline ./heapsort
The output of eu-readelf has:
0:14 0 0 0 0x0000000000401202 <main+0x42>
Looking at the dissembly of the code produced with "objdump -d
heapsort" this instruction is a zeroing of the register used for the
variable of i:
401202: 31 db xor %ebx,%ebx
Would expect that the eu-readelf output be (the "i=0" in the source code):
97:9 0 0 0 0x0000000000401202 <main+0x42></pre>
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