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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 --- - [MS ABI] Bad interaction between inalloca call and expanded memcpy"
href="http://llvm.org/bugs/show_bug.cgi?id=19012">19012</a>
</td>
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<th>Summary</th>
<td>[MS ABI] Bad interaction between inalloca call and expanded memcpy
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<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>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hans@chromium.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, rnk@google.com
</td>
</tr>
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<th>Blocks</th>
<td>12477, 18887
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The following program crashes when built with clang-cl:
(If the #if 1 is changed to #if 0, it doesn't crash. For some reason that
causes us not to expand the memcpy.)
struct Ptr {
~Ptr() {}
int *ptr;
};
#if 1
struct Arr {
struct {
struct {
char name[54];
} mailbox;
int texture_target;
int sync_point;
} mailbox_holder;
void *shared_memory;
struct shared_memory_size {
int width;
int height;
} memory_size;
};
#else
struct Arr {
char x[76];
};
#endif
void f(Ptr) {}
void g(Arr *a, Arr *b, Ptr *p) {
*a = *b; // memcpy, possibly expanded to rep movs, clobbering esi
f(*p); // inalloca call, causing chkstk, not expecting clobbered esi
};
int main() {
Ptr p = {};
Arr a = {}, b = {};
g(&a, &b, &p);
return 0;
}
(Reduced from Chromium's cc::CopyOutputResult::TakeTexture.)</pre>
</div>
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