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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 - Reg alloc reloads register three times in innermost vector loop, although there are many free regs"
href="https://bugs.llvm.org/show_bug.cgi?id=32722">32722</a>
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<th>Summary</th>
<td>Reg alloc reloads register three times in innermost vector loop, although there are many free regs
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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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>enhancement
</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>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=18320" name="attach_18320" title="reduced test case">attachment 18320</a> <a href="attachment.cgi?id=18320&action=edit" title="reduced test case">[details]</a></span>
reduced test case
I noticed that there are reloads of a register which is used as an address
inside a vectorized loop.
The loop is innermost, is a single block, and there are 10 unused registers in
the loop.
I am thinking that RA should be able to split live ranges around the loop?
bin/llc -O3 -mtriple=s390x-linux-gnu -mcpu=z13 -o out.s vecloopspills.ll
.LBB0_18: # %vector.body
# =>This Inner Loop Header: Depth=1
lgfr %r5, %r3
sllg %r5, %r5, 3
vlrepg %v0, 0(%r5,%r14)
ahik %r14, %r3, -2
lg %r13, 200(%r15) # 8-byte Folded Reload
lgfr %r14, %r14
sllg %r14, %r14, 3
vlrepg %v1, 0(%r14,%r13)
vmrhg %v0, %v1, %v0
lg %r13, 200(%r15) # 8-byte Folded Reload
vflcdb %v0, %v0
vsteg %v0, 0(%r14,%r13), 0
lg %r14, 200(%r15) # 8-byte Folded Reload
ahi %r3, 4
aghi %r4, -2
vsteg %v0, 0(%r5,%r14), 1
jne .LBB0_18</pre>
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