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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - va_copy for AArch64 doesn't work"
href="http://llvm.org/bugs/show_bug.cgi?id=18789">18789</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>va_copy for AArch64 doesn't work
</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>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: AArch64
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>liujiangning1@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>Created <span class=""><a href="attachment.cgi?id=12036" name="attach_12036" title="The .ll file to reproduce the run-time failure">attachment 12036</a> <a href="attachment.cgi?id=12036&action=edit" title="The .ll file to reproduce the run-time failure">[details]</a></span>
The .ll file to reproduce the run-time failure
The attached test case t.c is from LNT
$ cat t.c
#include <stdio.h>
#include <stdarg.h>
void testVaCopyArg(char *fmt, ...) {
va_list ap, aq;
char *s;
va_start(ap, fmt);
va_copy(aq, ap); /* test va_copy */
s = va_arg(aq, char *);
printf("string %s\n", s);
}
int main() {
testVaCopyArg("s", "abc");
return 0;
}
It fails at run-time with -O1 and above for aarch64 target, and it can pass
with -O0.
t.ll is generated with the following command line,
clang -O3 --target=aarch64-linux-gnuabi -mfpu=neon t.c -S -emit-llvm
With t.ll, we can confirm the bug is from backend, because the binary built
from "llc -O1" fail, while the binary built from "llc -O0" can pass.
1) -O0 case
// build with the following command line
llc -mtriple=aarch64-none-linux-gnueabi -O0 t.ll
clang --target=aarch64-linux-gnuabi t.s
// running a.out on foundation model shows correct result.
2) -O1 case
// build with the following command line
llc -mtriple=aarch64-none-linux-gnueabi -O1 t.ll
clang --target=aarch64-linux-gnuabi t.s
// running a.out on foundation model shows incorrect result or segmentation
fault.</pre>
</div>
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