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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - VirtRegMap.cpp should not just remove an identity copy which also has a impl-def of a super-reg"
href="https://llvm.org/bugs/show_bug.cgi?id=27156">27156</a>
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<th>Summary</th>
<td>VirtRegMap.cpp should not just remove an identity copy which also has a impl-def of a super-reg
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</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>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Register Allocator
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, matze@braunis.de
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16137" name="attach_16137" title="clang input">attachment 16137</a> <a href="attachment.cgi?id=16137&action=edit" title="clang input">[details]</a></span>
clang input
VirtRegMap removes identity copies, but that leads to machine-verifier
complaints if there is a def of a super reg as well.
I am not sure what the best fix is, but the patch attached seems to fix this by
transforming the COPY to an IMPLICIT_DEF when there is a def of a super-reg.
The patch assumes (arbitrarily) that there could only be one extra operand -
not sure if this is always true...
./bin/clang -cc1 -triple s390x-ibm-linux -S -disable-free -main-file-name
expr.c -mrelocation-model static -mthread-model posix -fmath-errno
-masm-verbose -mconstructor-aliases -fuse-init-array -target-cpu z13
-momit-leaf-frame-pointer -v -dwarf-column-info -debugger-tuning=gdb -O3
-ferror-limit 19 -fmessage-length 238 -funroll-loops -fobjc-runtime=gcc
-fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp
-o expr.s -x ir ./expr.bc -mllvm -verify-machineinstrs</pre>
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