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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 - Inconsistent debug info between break and stepi at -O1"
href="https://bugs.llvm.org/show_bug.cgi?id=46041">46041</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Inconsistent debug info between break 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=23523" name="attach_23523" title="the binary">attachment 23523</a> <a href="attachment.cgi?id=23523&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 5
Breakpoint 1: where = a.out`f + 21 at small.c:5:1, address = 0x0000000000401125
(lldb) r
Process 46982 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 46982 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x0000000000401125 a.out`f(x=-216) at small.c:5:1
2 if (x==-216 || x==-132)
3 return 1;
4 return 0;
-> 5 }
6
7 int main () {
8 volatile int i;
(lldb) fr var x
(int) x = -216
(lldb)
/************************************
As showed, when setting breakpoint on Line 5 (first hit), the value of "x" is
-216.
However, when step-i to Line 5, the value of "x" is -230 which is as expected:
************************************/
$ 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 + 5 at small.c:9:10, address =
0x0000000000401135
(lldb) r
Process 45549 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 45549 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x0000000000401135 a.out`main at small.c:9:10
6
7 int main () {
8 volatile int i;
-> 9 for (i = -230; i < -120; i++)
10 if (f(i) != (i==-216 || i==-132))
11 return 1;
12 return 0;
(lldb) si -c 14
Process 45549 stopped
* thread #1, name = 'a.out', stop reason = instruction step into
frame #0: 0x0000000000401128 a.out`f(x=-230) at small.c:5:1
2 if (x==-216 || x==-132)
3 return 1;
4 return 0;
-> 5 }
6
7 int main () {
8 volatile int i;
(lldb) fr var x
(int) x = -230
(lldb)
/******************* the small.c *************/
$ cat small.c
int f(int x) {
if (x==-216 || x==-132)
return 1;
return 0;
}
int main () {
volatile int i;
for (i = -230; i < -120; i++)
if (f(i) != (i==-216 || i==-132))
return 1;
return 0;
}</pre>
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