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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [AArch64] Unnecessary mask instruction on AArch64"
href="https://llvm.org/bugs/show_bug.cgi?id=30437">30437</a>
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<th>Summary</th>
<td>[AArch64] Unnecessary mask instruction on AArch64
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<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>
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<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@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>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>When compiling the following C program.
```c
typedef struct {
char a;
char b;
} ntuple2_t;
ntuple2_t g(void);
ntuple2_t f(void)
{
return g();
}
```
The LLVM IR generated on AArch64 is
```llvm
define i64 @f() local_unnamed_addr #0 {
%1 = tail call i64 @g() #2
%2 = and i64 %1, 65535
ret i64 %2
}
```
Here the `and` instruction is not really necessary since `g` and `f` follows
the same calling convention.</pre>
</div>
</p>
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