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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Many unnecessary mov instructions near call site"
href="https://llvm.org/bugs/show_bug.cgi?id=26114">26114</a>
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<th>Summary</th>
<td>Many unnecessary mov instructions near call site
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Register Allocator
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mcrosier@codeaurora.org
</td>
</tr>
<tr>
<th>CC</th>
<td>atrick@apple.com, hfinkel@anl.gov, llvm-bugs@lists.llvm.org, qcolombet@apple.com
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Test case:
void foo(char *c, short s, float X, char C, long long LL, int I, double D);
void test(short s, float X, char C, long long LL, int I, double D) {
foo("test", s, X, C, LL, I, D);
}
On AArch64 at -O3 the assembly output is as follows:
test:
mov w8, w3
mov x9, x2
mov w10, w1
mov w11, w0
adrp x0, .L.str
add x0, x0, :lo12:.L.str
mov w1, w11
mov w2, w10
mov x3, x9
mov w4, w8
b foo
We should be able to generate something like this:
test:
adrp x5, .LC0
mov w4, w3
mov x3, x2
mov w2, w1
mov w1, w0
add x0, x5, :lo12:.LC0
b foo
Which has 4 fewer moves.</pre>
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