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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 - Wrong constant folding"
href="https://bugs.llvm.org/show_bug.cgi?id=35240">35240</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Wrong constant folding
</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>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ishiura-compiler@ml.kwansei.ac.jp
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>LLVM + clang 6.0 for x86_64 miscompiles the following code.
% cat test.c
volatile int buff = 0;
void PRINTF(const int* s)
{
while(*s++) buff = *s;
}
char a = 0;
char b = 0;
short c = 0;
int d = 0;
int e = 0;
int main (void)
{
volatile short f = 1;
volatile int g = 1;
int h = ( 1 << c ) & 3;
a = 0 == g;
int i = 1 == g;
volatile int j = ((long)3>>g)%3;
volatile int k = (1*i)>>c;
c = a|f;
e = 3<<a;
b = d*i;
int l = (3>>a)/3;
if (h != 1) { PRINTF((const int*)&h); }
if (c != 1) __builtin_abort();
if (l != 1) __builtin_abort();
return 0;
}
% clang-6.0 -O1 test.c
% ./a.out
zsh: abort (core dumped) ./a.out
% clang-6.0 -O2 test.c
% ./a.out
zsh: abort (core dumped) ./a.out
% clang-6.0 -O3 test.c
% ./a.out
zsh: abort (core dumped) ./a.out
% clang-6.0 -Os test.c
% ./a.out
zsh: abort (core dumped) ./a.out
% clang-6.0 -v
clang version 6.0.0 (trunk 317078)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.0.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64</pre>
</div>
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