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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - opt miscompiles with "opt -O3 -gvn-hoist -newgvn""
href="https://bugs.llvm.org/show_bug.cgi?id=37660">37660</a>
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<th>Summary</th>
<td>opt miscompiles with "opt -O3 -gvn-hoist -newgvn"
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Vsevolod.Livinskij@frtk.ru
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
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<pre>Created <span class=""><a href="attachment.cgi?id=20383" name="attach_20383" title="Reproducer.">attachment 20383</a> <a href="attachment.cgi?id=20383&action=edit" title="Reproducer.">[details]</a></span>
Reproducer.
Opt produces incorrect code with opt -O3 -gvn-hoist -newgvn.
opt-bisect-limit points to Global Value Numbering on function
Reproducer:
<span class="quote">> cat func.c</span >
extern const long long c;
extern long long d;
extern int e;
extern long long *b;
extern long long f;
long long int foo() {
if (d) {
if (e - c)
;
else
f = (int)(307814 + c);
}
*b = (int)(c);
return *b;
}
<span class="quote">>$ cat driver.c</span >
#include <stdio.h>
long long a;
long long *b = &a;
const long long c = 1030468986380352444LL;
long long d;
int e;
long long f;
long long foo();
int main() {
printf("%llu\n", foo());
}
Error:
<span class="quote">>$ clang driver.c func.c
>$ ./a.out</span >
1564605372
<span class="quote">>$ clang -O3 -Xclang -disable-llvm-optzns -emit-llvm -c -o func.bc func.c
>$ opt -O3 -o func.ll func.bc -gvn-hoist -newgvn
>$ clang -c -o func.o func.ll
>$ clang func.o driver.c
>$ ./a.out</span >
1030468986380352444
LLVM version:
clang version 7.0.0 (trunk 333377)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /llvm/bin-trunk/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.5
Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.5
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64</pre>
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