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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 in 32-bit mode on valid code"
href="https://bugs.llvm.org/show_bug.cgi?id=38288">38288</a>
</td>
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<tr>
<th>Summary</th>
<td>clang miscompiles with "-newgvn" at -O3 in 32-bit mode on valid code
</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>It appears that it also affects the 64-bit mode.
clang-r333687: first working build
clang-r333691: 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 -m32 abc.c ; ./a.out
5
$ clang-trunk -mllvm -enable-newgvn -m32 -O3 abc.c ; ./a.out
0
$ cat abc.c
void printf();
struct {
int d;
} e, f;
int g, h, a, i, j;
char k, b;
short l = 5;
int __attribute__((noinline)) m(long long n) { return n; }
short(fn2)(char n) { return n; }
int(o)(int n, int p2) { return n - p2; }
void q(unsigned);
void r() {
char p = 0;
for (; p != 36; p = p + 9) {
int s;
h = 0;
for (; h > -20; --h) {
q(p);
s = 1 & ((1 | g && p || p) ^ 3);
i = o(p, s);
if (m(i))
;
else {
for (; b;)
fn2(p);
l = 0;
}
}
}
}
void q(unsigned n) {
if (m(0)) {
short c = 6;
if (m(j))
a = c = 0;
for (; k; k++)
e = f;
a = (e.d | n) % c;
}
}
int main() {
r();
printf("%d\n", l);
}</pre>
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