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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - After r313012, Assertion failed: (ExitCount != SE.getCouldNotCompute() && "Invalid loop count"), function generateOverflowCheck, file lib/Analysis/ScalarEvolutionExpander.cpp, line 2126."
href="https://bugs.llvm.org/show_bug.cgi?id=36032">36032</a>
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<th>Summary</th>
<td>After r313012, Assertion failed: (ExitCount != SE.getCouldNotCompute() && "Invalid loop count"), function generateOverflowCheck, file lib/Analysis/ScalarEvolutionExpander.cpp, line 2126.
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>release blocker
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dimitry@andric.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>As reported in <a href="https://bugs.freebsd.org/225345">https://bugs.freebsd.org/225345</a>, building the FreeBSD
games/scummvm port for AArch64 with clang 6.0.0 results in an assertion:
Assertion failed: (ExitCount != SE.getCouldNotCompute() && "Invalid loop
count"), function generateOverflowCheck, file
/usr/local/poudriere/jails/head-arm64/usr/src/contrib/llvm/lib/Analysis/ScalarEvolutionExpander.cpp,
line 2152.
This assertion still occurs with trunk r322755, and bisection shows it has
regressed with <a href="https://reviews.llvm.org/rL313012">https://reviews.llvm.org/rL313012</a> ("[LAA] Allow more run-time
alias checks by coercing pointer expressions to AddRecExprs") by Silviu
Baranga.
Minimized test case:
// clang -cc1 -triple aarch64-- -S -O1 -vectorize-loops graphics-minimized.cpp
struct {
void *a();
} b;
char c[6];
void d() {
unsigned char *e = (unsigned char *)b.a();
unsigned short f;
for (;;) {
for (unsigned g; g < 4; g++)
e[g] = c[g + f];
f += 4;
}
}
Note that -vectorize-loops is essential for reproducing the assertion.</pre>
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