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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Redundant jump table index xoring"
href="https://bugs.llvm.org/show_bug.cgi?id=39333">39333</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Redundant jump table index xoring
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>template<int> int foo();
typedef int (*int_fun)();
int_fun get_fun(unsigned int x)
{
switch(x&3)
{
case 0: return foo<0>;
case 1: return foo<1>;
case 2: return foo<2>;
case 3: return foo<3>;
}
return 0;
}
Current (SVN, X86-64, -O3):
get_fun(unsigned int):
and edi, 3
xor edi, 2
mov rax, qword ptr [8*rdi + .Lswitch.table.get_fun(unsigned int)]
ret
Prefered:
get_fun(unsigned int):
and edi, 3
mov rax, QWORD PTR CSWTCH.1[0+rdi*8]
ret</pre>
</div>
</p>
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