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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 (Combine redundant instructions on function)"
href="https://bugs.llvm.org/show_bug.cgi?id=46586">46586</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Clang produces wrong code with -O1 (Combine redundant instructions on function)
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</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>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Vsevolod.Livinskij@frtk.ru
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre><span class="quote">>$ clang++ -O1 func.cpp driver.cpp && ./a.out </span >
277562856
<span class="quote">>$ clang++ -O0 func.cpp driver.cpp && ./a.out </span >
0
Reproducer:
//func.cpp
extern int var_22;
void test(unsigned a, unsigned short b, unsigned short c, signed char d,
short e, unsigned char f, long long g,
unsigned char h[2][20][22][21][15]) {
for (bool i = 0; i < 1; i = f)
for (char j = 0; j < 9; j = 75)
for (bool k = 0; k < (bool)d /*1*/; k = 1)
for (int l = 0; l < c /*45282*/; l = g /*1453005525*/)
#pragma clang loop interleave(enable)
for (int m = 0; m < e + 31262 /*14*/; m += b - 55386 /*4*/)
var_22 = h[i][j][7][l][m] % a;
}
//driver.cpp
#include <stdio.h>
unsigned int var_0 = 1369684504U;
unsigned short var_2 = (unsigned short)55390;
unsigned short var_3 = (unsigned short)45282;
signed char var_4 = (signed char)115;
short var_5 = (short)-31248;
unsigned char var_7 = (unsigned char)161;
long long int var_9 = 7910119181202954965LL;
unsigned int var_22 = 3518480962U;
unsigned char arr_11 [2] [20] [22] [21] [15] ;
void test(unsigned int var_0, unsigned short var_2, unsigned short var_3,
signed char var_4, short var_5, unsigned char var_7, long long int var_9,
unsigned char arr_11 [2] [20] [22] [21] [15]);
int main() {
test(var_0, var_2, var_3, var_4, var_5, var_7, var_9, arr_11);
printf("%u\n", var_22);
}
Clang version:
clang version 11.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
120c5f1057dc50229f73bc75bbabf4df6ee50fef)</pre>
</div>
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