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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Inliner wrongly inlines functions that invoke setjmp()"
href="http://llvm.org/bugs/show_bug.cgi?id=18206">18206</a>
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<th>Summary</th>
<td>Inliner wrongly inlines functions that invoke setjmp()
</td>
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<th>Product</th>
<td>tools
</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>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>opt
</td>
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<th>Assignee</th>
<td>mseaborn@chromium.org
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<th>Reporter</th>
<td>mseaborn@chromium.org
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>The inliner will avoid inlining functions that call setjmp() using a "call"
instruction, but it doesn't do the same for functions that call setjmp() using
an "invoke" instruction.
Here's an example of a miscompilation that can result:
#include <stdio.h>
typedef char jmp_buf[1000];
extern "C" {
// Declare setjmp() without "__attribute__((nothrow))":
int setjmp(jmp_buf env);
void longjmp(jmp_buf env, int val);
}
jmp_buf buf;
static void inner(int *ptr) throw() {
*ptr = 0;
if (!setjmp(buf)) {
*ptr = 1;
longjmp(buf, 1);
} else {
puts(*ptr ? "passed" : "failed");
}
}
int main() {
int ptr;
inner(&ptr);
return 0;
}
This currently prints "passed" when compiled with -O0, but "failed" when
compiled with -O2.
An "invoke" of setjmp() can occur if:
* setjmp() is called in an exception-handling context, e.g. in C++ a
destructor implicitly declared as "nothrow".
* setjmp() is declared without "nothrow". e.g. glibc's headers declare
setjmp() with "nothrow", but not all headers do.
I'll prepare a fix.</pre>
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</p>
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