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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [AArch64] Suboptimal immediate encoding with add/sub"
href="https://bugs.llvm.org/show_bug.cgi?id=40055">40055</a>
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<th>Summary</th>
<td>[AArch64] Suboptimal immediate encoding with add/sub
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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
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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>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: AArch64
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>amanieu@gmail.com
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<th>CC</th>
<td>arnaud.degrandmaison@arm.com, llvm-bugs@lists.llvm.org, peter.smith@linaro.org, Ties.Stuij@arm.com
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<pre>This IR:
%2 = sub i64 %0, 72340172838076673 ; 0x0101010101010101
Generates the following assembly:
mov x8, #-72340172838076674
movk x8, #65279
add x0, x0, x8
However the immediate can be encoded in a single instruction if it is not
negated:
mov x8, #72340172838076673
sub x0, x0, x8</pre>
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