<html>
<head>
<base href="https://bugs.llvm.org/">
</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 - Failure to combine assumptions on range of value of variable"
href="https://bugs.llvm.org/show_bug.cgi?id=45686">45686</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Failure to combine assumptions on range of value of variable
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>void foo(int a, int b, bool c)
{
__builtin_assume(a < 234);
__builtin_assume(b > 789);
int d = (c ? a : b);
if (d >= 234 && d <= 789)
g();
}
GCC optimizes the entire function out, LLVM does not. Most likely we'd want
LLVM to combine the assumptions on `a` and `b` in such a way that `d >= 234 &&
d <= 789` would be considered always false afterwards
Comparison here : <a href="https://godbolt.org/z/f4uWiY">https://godbolt.org/z/f4uWiY</a></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>