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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [LICM] loads hoisted out of vectorized loop but not from scalar loop."
href="https://bugs.llvm.org/show_bug.cgi?id=39989">39989</a>
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<th>Summary</th>
<td>[LICM] loads hoisted out of vectorized loop but not from scalar loop.
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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
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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
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<th>Component</th>
<td>Loop Optimizer
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=21218" name="attach_21218" title="reduced testcase">attachment 21218</a> <a href="attachment.cgi?id=21218&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase
I found a few cases of a loop with loads from loop-invariant addresses that get
vectorized. I am not sure why, but the loads in the vectorized loop get hoisted
by LICM, while those in the scalar loop remain inside the loop.
I wonder why that is - is this a known issue/behaviour or is this something to
be fixed in LICM?
Attached is a reduced test case which is not perfect, but at least has this
behaviour well exhibited in vector.body and (the original scalar) bb27.us.i
loops.
clang -cc1 -triple s390x-ibm-linux -S -save-temps=cwd -fmath-errno -target-cpu
z13 -v -O3 -w -vectorize-loops -vectorize-slp -o out.ll -emit-llvm
tc_licm_vec_scal.ll -mllvm -unroll-count=1</pre>
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