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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - X86 ISel gets stuck in infinite loop"
href="https://bugs.llvm.org/show_bug.cgi?id=41066">41066</a>
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<th>Summary</th>
<td>X86 ISel gets stuck in infinite loop
</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
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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>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>andrew@scheidecker.net
</td>
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<pre>Created <span class=""><a href="attachment.cgi?id=21595" name="attach_21595" title="IR that triggers bug">attachment 21595</a> <a href="attachment.cgi?id=21595&action=edit" title="IR that triggers bug">[details]</a></span>
IR that triggers bug
Using SVN revision 356146 (from 2019/03/14), llc gets stuck in a loop on the
attached input, when run with the command-line:
llc llvm-lock2.ll -mcpu=skylake-avx512
Using llc from the LLVM 6.0 release does not get stuck in a loop.
Running it with e.g. -mcpu=skylake also does not get stuck in a loop. Based on
this, I've assumed this is an X86/AVX512 target specific bug.
Passing -debug prints the following in a loop:
Combining: t13: v2i64 = or t1518, t2
Combining: t1518: v2i64 = vselect t1517, t11, t10
Creating new node: t1519: v2i1 = xor t1517, t24
Creating new node: t1520: v2i64 = vselect t1519, t10, t11
... into: t1520: v2i64 = vselect t1519, t10, t11
Combining: t13: v2i64 = or t1520, t2
Combining: t1520: v2i64 = vselect t1519, t10, t11
Creating new node: t1521: v2i1 = xor t1519, t24
Creating new node: t1522: v2i64 = vselect t1521, t11, t10
... into: t1522: v2i64 = vselect t1521, t11, t10</pre>
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