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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect optimization in memcpyopt with longjmp and volatile locals"
href="https://llvm.org/bugs/show_bug.cgi?id=27848">27848</a>
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<th>Summary</th>
<td>Incorrect optimization in memcpyopt with longjmp and volatile locals
</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>
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<th>OS</th>
<td>Windows NT
</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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>eli.friedman@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Testcase:
#include <setjmp.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
int zz = 1;
__attribute((noinline))
void g(volatile int* y, jmp_buf *b) {
*y = 10;
if (zz) longjmp(*b, 2);
}
__attribute((noinline))
int f() {
volatile int x, y;
x = 1;
jmp_buf b;
if (setjmp(b)) return x;
g(&y, &b);
memcpy((void*)&x, (void*)&y, 4);
return x;
}
int main() { if (f() != 1) abort(); }
Runs correctly with gcc or clang -O0; aborts with clang -O2. I'm pretty sure
it's a bug in memcpyopt: it's trying to do call slot optimization on y.</pre>
</div>
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