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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - AArch64 backend does not handle contract math."
href="https://bugs.llvm.org/show_bug.cgi?id=35091">35091</a>
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<th>Summary</th>
<td>AArch64 backend does not handle contract math.
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>5.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: AArch64
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>yyc1992@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Test case:
```
target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-unknown-linux-gnu"
define double @f1(double, double, double) {
%4 = call double @llvm.fmuladd.f64(double %0, double %1, double %2)
ret double %4
}
define double @f2(double, double, double) {
%4 = fmul contract double %0, %1
%5 = fadd contract double %4, %2
ret double %5
}
declare double @llvm.fmuladd.f64(double %a, double %b, double %c)
```
According to LangRef, the two function should be the same and should both use
fma or mul and add depending on what the backend think is faster. However,
running with `llc -O3` only the first one generates an fma instruction and the
second one uses a mul and an add.
ARM backend might have the same issue.</pre>
</div>
</p>
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