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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 -O2 on valid code"
href="https://bugs.llvm.org/show_bug.cgi?id=38260">38260</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang miscompiles with "-newgvn" at -O2 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>clang-r312400: first working build
clang-r312401: next failing build
$ clang-trunk abc.c ; ./a.out
0
$ clang-trunk -mllvm -enable-newgvn -O2 abc.c ; ./a.out
-1
$ clang-trunk -v
clang version 7.0.0 (trunk 337641)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ cat abc.c
int printf(char *, ...);
long a;
int g, h, i, k, l, b, d;
char m, p, q, s, j;
struct {
int n;
} r = {9}, o;
short f;
int __attribute__((noinline)) t() {
volatile int c = 0;
return a;
}
char(u)(char v, char w) { return v + w; }
char(x)(char v, char w) { return v + w; }
static unsigned y() {
int e = 0;
for (; e != 5; e++) {
if (e && r.n)
--p;
b = i == 0 ? 0 : h / i;
k = b;
if (b) {
volatile int c = 0;
}
if (a)
g &= t();
j = a = f * m;
if (u(r.n && d, d))
for (; s <= 7; s = u(s, 5))
;
for (; q < 9; q = x(q, 3))
r = o;
l--;
}
}
int main() {
y();
printf("%d\n", p);
}</pre>
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