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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [AArch64] Generate sqdmlal"
href="https://bugs.llvm.org/show_bug.cgi?id=50653">50653</a>
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<th>Summary</th>
<td>[AArch64] Generate sqdmlal
</td>
</tr>
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<th>Product</th>
<td>new-bugs
</td>
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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>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>sjoerd.meijer@arm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Raising this missed optimisation opportunity in case someone finds this
interesting.
For this input:
#include "arm_neon.h"
int32_t
t_vqdmlalh_lane_s16 (int32_t a, int16_t b, int16x4_t c) {
return vqdmlalh_lane_s16 (a, b, c, 0);
}
We are not generating this multiply-accumulate variant that gcc generates:
t_vqdmlalh_lane_s16:
dup v2.4h, w1
fmov s1, w0
sqdmlal s1, h2, v0.h[0]
fmov w0, s1
ret
We get this instead:
t_vqdmlalh_lane_s16: // @t_vqdmlalh_lane_s16
fmov s1, w1
sqdmull v0.4s, v1.4h, v0.4h
fmov s1, w0
sqadd s0, s1, s0
fmov w0, s0
ret
See also <a href="https://godbolt.org/z/41nMxM5q1">https://godbolt.org/z/41nMxM5q1</a></pre>
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