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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SCEV][LSR] Broken IR after LSR pass when compiling for armv8"
href="https://bugs.llvm.org/show_bug.cgi?id=42436">42436</a>
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<th>Summary</th>
<td>[SCEV][LSR] Broken IR after LSR pass when compiling for armv8
</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>All
</td>
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<th>OS</th>
<td>All
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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
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<th>Component</th>
<td>Global Analyses
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>eleviant@accesssoftek.com
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</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=22161" name="attach_22161" title="reproducer">attachment 22161</a> <a href="attachment.cgi?id=22161&action=edit" title="reproducer">[details]</a></span>
reproducer
Compilation of large project for ARMv8 ended up with broken assembly code in
vector<_Tp, _Allocator>::insert(const_iterator __position, _ForwardIterator
__first, _ForwardIterator __last)
I investigated the problem and it seems to be in loop-reduce pass which creates
'sub' binary operation with these operands:
%8 = ptrtoint i8* %7 to i32
...
%10 = ptrtoint i8* undef to i32
...
.preheader:
%120 = sub i32 %10, %8
which should result to zero, but is in fact undefined.
One can reproduce it using the attached IR file and running:
opt -S -loop-reduce insert.ll</pre>
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