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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Bad machine code: No live subrange at use"
href="https://bugs.llvm.org/show_bug.cgi?id=42552">42552</a>
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<th>Summary</th>
<td>Bad machine code: No live subrange at use
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Register Allocator
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, quentin.colombet@gmail.com
</td>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=22213" name="attach_22213" title="reduced testcase">attachment 22213</a> <a href="attachment.cgi?id=22213&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase
llc ./tc.ll -mtriple=s390x-linux-gnu -mcpu=z13 -o out.s -verify-machineinstrs
-systemz-subreg-liveness -lsr-complexity-limit=8 -consthoist-gep
-pre-RA-sched=list-ilp -disable-machine-licm -disable-machine-cse
-misched=ilpmin
*** Bad machine code: No live subrange at use ***
- function: main
- basic block: %bb.5 bb132 (0x5db6d48) [1608B;4560B)
- instruction: 3600B undef %182.subreg_h64:gr128bit = COPY
%181.subreg_h64:gr128bit
- operand 1: %181.subreg_h64:gr128bit
- interval: %181 [3476r,3600r:0) 0@3476r L00000008 [3476r,3600r:0) 0@3476r
weight:1.202965e+07
- at: 3600B
LLVM ERROR: Found 1 machine code errors.
There is something strange here: If I rename tc.ll to ./tc_nolive_subr_atuse.ll
there seem to be a random variation of the pre-RA-sched=list-ilp scheduler, as
the MF is not then identical, and the bug disappears! (I guess this should be
reported as a separate bug?)
What's more: if I do -stop/start-before=simple-register-coalescing, the bug
also becomes hidden...
I am using r365452 (2c0337f) "Retire VS2015 Support".</pre>
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