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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - x86_stdcallcc: Assertion hit when passing more than 2^16 bytes on the stack"
href="http://llvm.org/bugs/show_bug.cgi?id=20292">20292</a>
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<th>Summary</th>
<td>x86_stdcallcc: Assertion hit when passing more than 2^16 bytes on the stack
</td>
</tr>
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<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>code@klickverbot.at
</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>Generating code for the following piece of IR currently asserts as
X86TargetLowering::LowerReturn tries to fit the number of bytes to pop on
function exit into a 16 bit constant:
---
target datalayout =
"e-p:32:32:32-S128-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f16:16:16-f32:32:32-f64:32:64-f128:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
target triple = "i386-unknown-linux-gnu"
%bar = type { [16385 x i32] }
define x86_stdcallcc void @foo(%bar* byval %s_arg) {
ret void
}
---
Of course, passing such a large object on the stack is rather nonsensical, but
I think this is somewhat problematic as IR that passes the validator/… silently
leads to wrong code being generated ("ret $4") when LLVM is built without
assertions.
Is it worth supporting this, or should there simply be a fatal error in
X86TargetLowering::LowerReturn when encountering such large sizes?</pre>
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