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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Clang breaks badly on too large object sizes"
href="https://bugs.llvm.org/show_bug.cgi?id=52036">52036</a>
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<th>Summary</th>
<td>Clang breaks badly on too large object sizes
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
</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>C
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>struct s {
char arr[922337203685477587];
char arr2[922337203685477587];
char arr3[922337203685477587];
char arr4[922337203685477587];
char arr5[922337203685477587];
char arr6[922337203685477587];
char arr7[922337203685477587];
char arr8[922337203685477587];
char arr9[922337203685477587];
char arr10[922337203685477587];
char arr11[922337203685477587];
char arr12[922337203685477587];
};
s x;
void f()
{
volatile s x = {};
}
The size of `s` is simply not representable in `size_t`, which seems to break
Clang in multiple ways:
- It gives me a warning telling me that "stack frame size exceeds limit" when
the warning tells me of a stack frame size that's smaller than the limit (it
tells me the stack frame size is 1717986984 and that the limit is 4294967295)
- The emitted assembly tries to call memset with a size of 461168601842738840,
which is smaller than even a single one of the arrays in `s`.
Probably Clang should just error on the declaration of `s`, as GCC does:
<source>:1:8: error: size of type 's' is too large ('11068046444225731044'
bytes)
1 | struct s {
| ^</pre>
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