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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 - [PostRA Machine Sink] Sunk instruction corrupts liveness tracking"
href="https://bugs.llvm.org/show_bug.cgi?id=36902">36902</a>
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<th>Summary</th>
<td>[PostRA Machine Sink] Sunk instruction corrupts liveness tracking
</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>Common Code Generator Code
</td>
</tr>
<tr>
<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
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=20123" name="attach_20123" title="reduced testcase (for clang)">attachment 20123</a> <a href="attachment.cgi?id=20123&action=edit" title="reduced testcase (for clang)">[details]</a></span>
reduced testcase (for clang)
This instruction:
renamable $r0l = COPY renamable $r12l, implicit killed $r12q
copies a subreg ($r12l) of $r12q which is killed. It is sunk into this block:
bb.8..preheader26:
; predecessors: %bb.6
successors: %bb.10(0x50000000), %bb.9(0x30000000)
liveins: $r4d, $r0l, $r13l
renamable $r0d = LGFR killed renamable $r0l
renamable $r11d = LGFR killed renamable $r13l
CHIMux renamable $r4l, 0, implicit-def $cc, implicit killed $r4d
BRC 14, 10, %bb.10, implicit killed $cc
like
bb.8..preheader26:
; predecessors: %bb.6
successors: %bb.10(0x50000000), %bb.9(0x30000000)
liveins: $r4d, $r13l, $r12l
renamable $r0l = COPY renamable $r12l, implicit killed $r12q
renamable $r0d = LGFR killed renamable $r0l
renamable $r11d = LGFR killed renamable $r13l
CHIMux renamable $r4l, 0, implicit-def $cc, implicit killed $r4d
BRC 14, 10, %bb.10, implicit killed $cc
Note that another subreg of $r12q was already live into this MBB
($r13l). Since the sunk instruction now kills $r13l before its use,
machine veririer says:
*** Bad machine code: Using an undefined physical register ***
- function: decode_one_b8block
- basic block: %bb.8 .preheader26 (0x2aa41875a08)
- instruction: renamable $r11d = LGFR killed renamable $r13l
- operand 1: killed renamable $r13l
clang line:
bin/clang -march=z13 -mllvm -disable-machine-dce -mllvm -disable-machine-sink
-mllvm -extra-vectorizer-passes -mllvm -enable-tbaa=false -mllvm
-verify-machineinstrs -O3 -w -o ./out.ll ./tc_machinesink.ll
llc line:
bin/llc -mtriple=s390x-linux-gnu -mcpu=z13 -start-before=postra-machine-sink
./tc_machinesink.mir -O3 -verify-machineinstrs</pre>
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