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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang miscompiles with "newgvn" at -O3 on valid code (32-bit only)"
href="https://bugs.llvm.org/show_bug.cgi?id=38304">38304</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang miscompiles with "newgvn" at -O3 on valid code (32-bit only)
</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>enhancement
</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>helloqirun@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>clang-r325122: first working build
clang-r325127: next failing build
$ clang-trunk -v
clang version 7.0.0 (trunk 337816)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ clang-trunk -O3 -m32 abc.c ; ./a.out
5
$ clang-trunk -mllvm -enable-newgvn -m32 -O3 abc.c ; ./a.out
0
$ cat abc.c
void printf();
int c, d, e, f, g = 5, i, j;
char h, k;
int __attribute__((noinline)) l(long long m) { return m; }
int(n)(int m, int p2) { return m - p2; }
short o() {
k = 1;
for (; k; k++) {
if (d)
continue;
return 1;
}
for (; i <= 5; i++) {
g = 0;
if (l(0))
e = 3;
}
return 1;
}
void p(unsigned m) {
if (l(0)) {
short a;
for (; h; h++)
a = e;
f = (e | m) % a;
}
}
short fn5() {
int q;
char b = 0;
for (; b != 36; b = b + 9) {
d = 0;
for (; d > -20; --d) {
p(b);
o();
j = 1 & ((1 | c && b || b) ^ 3);
q = n(b, j);
if (l(q))
break;
}
}
return b;
}
int main() {
fn5();
printf("%d\n", g);
}</pre>
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