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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - PowerPC fast isel little endian issue with FP to INT conversion"
href="https://llvm.org/bugs/show_bug.cgi?id=26180">26180</a>
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<th>Summary</th>
<td>PowerPC fast isel little endian issue with FP to INT conversion
</td>
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<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: PowerPC
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>anton@samba.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>I hit an issue when bootstrapping rust. It boils down to:
600c: 5e 0e 20 fc fctidz f1,f1
6010: 70 00 21 d8 stfd f1,112(r1)
6014: 74 00 81 80 lwz r4,116(r1)
We load the wrong 4 bytes in little endian. A testcase:
define i32 @bad(double %x) {
%1 = fptoui double %x to i32
ret i32 %1
}
I struggled to reproduce this at first. POWER5 and later support fctiwz, and
looks like fctwiz writes the result twice:
f1 50000 (raw 0x40e86a0000000000)
...
fctiwuz f1,f1
...
f1 1.060997895729669e-309 (raw 0x0000c3500000c350)
So it seems we get lucky. I also need to work out why rust is emitting fctidz
and not the newer fctiwz, might be an LLVM initialization issue.</pre>
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</p>
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