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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 - clang produces wrong code with -O1 to -Os"
href="https://bugs.llvm.org/show_bug.cgi?id=45631">45631</a>
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<th>Summary</th>
<td>clang produces wrong code with -O1 to -Os
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>haoxintu@gmail.com
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<div>
<pre>Hi, test.c
#include<stdio.h>
long a;
int b = 94, tf_0_var_795;
void c(long long *d, int e) { *d = e; }
int main() {
tf_0_var_795 = !(~0 + 7 << b);
c(&a, tf_0_var_795);
printf("%d\n", a);
}
Clang produces wrong code with -O1 to -Os, the correct output is 0, but it gets
wrong with 1.
$ clang-trunk -w test.c && ./a.out
0
$ clang-trunk -w -O1 test.c && ./a.out
1
$ clang-trunk -w -O2 test.c && ./a.out
1
$ clang-trunk -w -O3 test.c && ./a.out
1
$ clang-trunk -w -Os test.c && ./a.out
1
Also, I have tested almost all released clang versions I used, the results are
the same as I reported above.</pre>
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