<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <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 behaviors at -O0"
   href="https://bugs.llvm.org/show_bug.cgi?id=46032">46032</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>inconsistent behaviors at -O0
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>lldb
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </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>All Bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>lldb-dev@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>yangyibiao@hust.edu.cn
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>jdevlieghere@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=23517" name="attach_23517" title="the binary">attachment 23517</a> <a href="attachment.cgi?id=23517&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 -O0 -g small.c

$ lldb a.out
(lldb) target create "a.out"
Current executable set to '/home/yibiao/Debugger/a.out' (x86_64).
(lldb) b 13
Breakpoint 1: where = a.out`f + 90 at small.c:13:5, address =
0x000000000040118a
(lldb) r
Process 336948 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 336948 exited with status = 0 (0x00000000)
(lldb) 


/************************************
As showed, when setting breakpoint on Line 13, lldb exit directly.
However, when step-i, Line 13 is hit by lldb as follow:
************************************/


$ 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 + 15 at small.c:24:3, address =
0x00000000004011cf
(lldb) r
Process 336902 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 336902 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x00000000004011cf a.out`main at small.c:24:3
   21   }
   22   
   23   int main() {
-> 24     f("u3");
   25     return 0;
   26   }
(lldb) si -c 674
Process 336902 stopped
* thread #1, name = 'a.out', stop reason = instruction step into
    frame #0: 0x000000000040118f a.out`f(p="u3") at small.c:13:16
   10       r = strcmp(p, c[m]);
   11       if(r<0) {
   12         l = m;
-> 13       } else if(r>0) {
   14         s = m;
   15       } else {
   16         return 1;
(lldb)



$ cat small.c
#include <string.h>
char *c[3]={"u1", "u2", "u3"};

int f(char *p)
{
  int r, m=3, s=0, l=3;

  while(1) {
    m = (s+l)/2;
    r = strcmp(p, c[m]);
    if(r<0) {
      l = m;
    } else if(r>0) {
      s = m;
    } else {
      return 1;
    }
  }

  return 0;
}

int main() {
  f("u3");
  return 0;
}</pre>
        </div>
      </p>


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