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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [GlobalISel] i1 boolean is signed extended to -1"
href="https://bugs.llvm.org/show_bug.cgi?id=36719">36719</a>
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<th>Summary</th>
<td>[GlobalISel] i1 boolean is signed extended to -1
</td>
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<th>Product</th>
<td>new-bugs
</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>normal
</td>
</tr>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>mgrang@codeaurora.org
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</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>echo "bool a() { return true; }" > a.cpp
clang -x c++ -target aarch64-linux-gnu a.cpp -S -o -
a:
mov w8, #-1 <-- 1 bit boolean true becomes -1.
mov w0, w8
ret
This bug is uncovered when GlobalISel is enabled by default at -O0:
<a href="https://reviews.llvm.org/D41362">https://reviews.llvm.org/D41362</a>
I attempted to *fix* this here: <a href="https://reviews.llvm.org/D44410">https://reviews.llvm.org/D44410</a>. But from the
comments I guess the problem is elsewhere.
Basically, an i1 is sign extended to a -1 in GlobalISel legalization. Instead,
a 1 bit boolean should be zero extended.</pre>
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