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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 code (Uncertain results) with "opt -inline -gvn -jump-threading -reg2mem -inferattrs -structurizecfg -gvn""
href="https://bugs.llvm.org/show_bug.cgi?id=41637">41637</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code (Uncertain results) with "opt -inline -gvn -jump-threading -reg2mem -inferattrs -structurizecfg -gvn"
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>cszide@163.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=21837" name="attach_21837" title=".bc file of the source code">attachment 21837</a> <a href="attachment.cgi?id=21837&action=edit" title=".bc file of the source code">[details]</a></span>
.bc file of the source code
$clang -v
clang version 9.0.0 (trunk 355281)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build4/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$clang -O3 -c -emit-llvm -mllvm -disable-llvm-optzns small.c -o small.bc
$clang small.bc -o small.out && ./small.out
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
---------------
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
65535 0 0 0 0 0 0 0 0
In this step, without optimization, the results are identical after running
many times.
$opt -inline -gvn -jump-threading -reg2mem -inferattrs -structurizecfg -gvn
small.bc -o small-opt.bc
$clang small-opt.bc -o small1.out && ./small1.out
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
---------------
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
27135 0 0 0 0 0 0 0 0
$ clang small-opt.bc -o small1.out && ./small1.out
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
---------------
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
25599 0 0 0 0 0 0 0 0
In this step, the results of optimized code are different after running many
times.
--------------------------------------------
#include<stdio.h>
//------------------------
typedef signed char int8_t;
typedef int int32_t;
/* Unsigned. */
typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
uint32_t a, e;
uint16_t b[5][9];
int8_t c[10];
uint16_t *d = &b[4][0];
int32_t *f(uint16_t h, uint16_t k);
uint8_t g() {
f(0, 0);
return 0;
}
int32_t *f(uint16_t h, uint16_t k) {
l:
if (k < *d)
for (; e;) {
int8_t *m = &c[2];
*m = e;
if (a)
goto l;
}
--*d;
return 0;
}
void main() {
int i, j, n = 0;
for (i = 0; i < 5; i++){
for (j = 0; j < 9; j++){
printf("%d ", b[i][j]);
}
printf("\n");
}
printf("---------------\n");
g();
for (i = 0; i < 5; i++){
for (j = 0; j < 9; j++){
printf("%d ", b[i][j]);
}
printf("\n");
}
}</pre>
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