<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - UBSan: constant operand required for __builtin_address()" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D24256&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=bPJX3fM4CAkdRTYWQS87FeONvbKF3ejxNRZTQTrKAC4&s=2912eHjHurTHSP2MMrNAG-as2q0UpEC6aTptZYtojMQ&e=">24256</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>UBSan: constant operand required for __builtin_address()
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Wolfgang_Pieb@playstation.sony.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>//========================
void *gGetCallStack() { return __builtin_frame_address(0 + 0); }
//========================
Compiled with the undefined behavior sanitizer enabled:
clang -fsanitize=undefined -c t.cpp
produces an assertion:
clang-3.7: /home/user/src/llvm/trunk/llvm/include/llvm/Support/Casting.h:237:
typename llvm::cast_retty<X, Y*>::ret_type llvm::cast(Y*) [with X =
llvm::ConstantInt; Y = llvm::Value; typename llvm::cast_retty<X, Y*>::ret_type
= llvm::ConstantInt*]: Assertion `isa<X>(Val) && "cast<Ty>() argument of
incompatible type!"' failed.
This is caused by clang not folding 0 + 0 but instead generating code
for it. The lowering of the LLVM builtin llvm.frameaddress is not prepared
for this and expects a constant.
This appears to be similar to <a class="bz_bug_link
bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - Constant builtin operands should be emitted as constants, even with UBSan" href="show_bug.cgi?id=23517">bug 23517</a> for ARM builtins.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>