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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to optimize some 64-bit constants in -Oz"
href="https://bugs.llvm.org/show_bug.cgi?id=48979">48979</a>
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<th>Summary</th>
<td>Failure to optimize some 64-bit constants in -Oz
</td>
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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>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>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, pengfei.wang@intel.com, spatel+llvm@rotateright.com
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<p>
<div>
<pre>int64_t f()
{
return 0x1234567800000000;
}
With -Os, GCC emits this:
f():
mov eax, 38177487
sal rax, 35
ret
Clang -Oz emits this:
f():
movabs rax, 1311768464867721216
ret
GCC saves 1 byte over LLVM here.</pre>
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