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<head>
<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 - Inconsistent debug info between step and stepi at -O1"
href="https://bugs.llvm.org/show_bug.cgi?id=46042">46042</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Inconsistent debug info between step and stepi at -O1
</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>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>yangyibiao@hust.edu.cn
</td>
</tr>
<tr>
<th>CC</th>
<td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=23524" name="attach_23524" title="the binary">attachment 23524</a> <a href="attachment.cgi?id=23524&action=edit" title="the binary">[details]</a></span>
the binary
$ clang --version
clang version 11.0.0 (/home/yibiao/.cache/yay/llvm-git/llvm-project
871beba234a83a2a02da9dedbd59b91a1bfbd7af)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
$ lldb --version
lldb version 11.0.0
clang revision 871beba234a83a2a02da9dedbd59b91a1bfbd7af
llvm revision 871beba234a83a2a02da9dedbd59b91a1bfbd7af
$ clang -O1 -g small.c
$ lldb a.out
(lldb) target create "a.out"
Current executable set to '/home/yibiao/Debugger/a.out' (x86_64).
(lldb) b main
Breakpoint 1: where = a.out`main + 1 at small.c:26:8, address =
0x00000000004011a1
(lldb) r
Process 79491 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 79491 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004011a1 a.out`main at small.c:26:8
23 }
24
25 int main() {
-> 26 if (!f("u3"))
27 return 1;
28 return 0;
29 }
(lldb) step
Process 79491 stopped
* thread #1, name = 'a.out', stop reason = step in
frame #0: 0x0000000000401157 a.out`f(p="u3") at small.c:9:11
6 int s=0, m=3, l=3, lm=6, r;
7
8 while(1) {
-> 9 m = (s+l)/2;
10 if (lm==m) {
11 break;
12 }
(lldb) step
Process 79491 stopped
* thread #1, name = 'a.out', stop reason = step in
frame #0: 0x0000000000401164 a.out`f(p="u3") at small.c:10:11
7
8 while(1) {
9 m = (s+l)/2;
-> 10 if (lm==m) {
11 break;
12 }
13 r = strcmp(p, T[m]);
(lldb) step
Process 79491 stopped
* thread #1, name = 'a.out', stop reason = step in
frame #0: 0x000000000040116c a.out`f(p="u3") at small.c:13:19
10 if (lm==m) {
11 break;
12 }
-> 13 r = strcmp(p, T[m]);
14 if (r < 0) {
15 l = m;
16 } else if (r > 0) {
(lldb) fr var s
(int) s = 1
(lldb)
/*********************************************
As showed above, step into Line 13 (first hit), the value of "s" is 1.
When using step-i, the value of "s" is 0 which is as expected.
*********************************************/
$ lldb a.out
(lldb) target create "a.out"
Current executable set to '/home/yibiao/Debugger/a.out' (x86_64).
(lldb) b main
Breakpoint 1: where = a.out`main + 1 at small.c:26:8, address =
0x00000000004011a1
(lldb) r
Process 79554 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 79554 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004011a1 a.out`main at small.c:26:8
23 }
24
25 int main() {
-> 26 if (!f("u3"))
27 return 1;
28 return 0;
29 }
(lldb) si -c 12
Process 79554 stopped
* thread #1, name = 'a.out', stop reason = instruction step into
frame #0: 0x000000000040116c a.out`f(p="u3") at small.c:13:19
10 if (lm==m) {
11 break;
12 }
-> 13 r = strcmp(p, T[m]);
14 if (r < 0) {
15 l = m;
16 } else if (r > 0) {
(lldb) fr var s
(int) s = 0
(lldb)
$ cat small.c
#include <string.h>
char *T[3] = {"u1", "u2", "u3"};
int f(char *p) {
int s=0, m=3, l=3, lm=6, r;
while(1) {
m = (s+l)/2;
if (lm==m) {
break;
}
r = strcmp(p, T[m]);
if (r < 0) {
l = m;
} else if (r > 0) {
s = m;
} else {
return 1;
}
}
return 0;
}
int main() {
if (!f("u3"))
return 1;
return 0;
}</pre>
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