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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Global register variable support"
href="http://llvm.org/bugs/show_bug.cgi?id=16877">16877</a>
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<tr>
<th>Summary</th>
<td>Global register variable support
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>owen.yamauchi+llvm@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>register int num asm("ebx");
void f() {
num = 12345;
}
void g() {
int x;
f();
asm("mov %%ebx, %0" : "=r"(x));
// x is now 12345
}
clang parses this successfully and prints a helpful error message; the bug is
that it doesn't actually support this (GNU extension) functionality.
This feature is useful in low-level software like JIT compilers. I realize this
requires support in LLVM (some way to express this constraint in LLIR for a
start), so I'm not sure exactly where this bug should be filed.</pre>
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