[llvm-bugs] [Bug 46047] New: inconsistent behaviors at -O3

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=46047

            Bug ID: 46047
           Summary: inconsistent behaviors at -O3
           Product: lldb
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at lists.llvm.org
          Reporter: yangyibiao at hust.edu.cn
                CC: jdevlieghere at apple.com, llvm-bugs at lists.llvm.org

$ 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 -O3 -g small.c

$ lldb a.out
(lldb) target create "a.out"
Current executable set to '/home/yibiao/Debugger/a.out' (x86_64).
(lldb) b 11
Breakpoint 1: where = a.out`main + 79 at small.c:11:3, address =
0x000000000040117f
(lldb) r
Process 565482 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 565482 exited with status = 0 (0x00000000) 
(lldb) 


/****************************************
As showed above, Line 11 is not hit by LLDB when setting breakpoint at Line 11.
However, Line 11 is hit by LLDB when using step-i. 
****************************************/

$ 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:6:10, address =
0x0000000000401131
(lldb) r
Process 565440 launched: '/home/yibiao/Debugger/a.out' (x86_64)
Process 565440 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000000000401131 a.out`main at small.c:6:10
   3    
   4    int main() {
   5      for (int e=0; e<10; e++)
-> 6        d[e] = 1;
   7      if (d[0])
   8        c = a = (b == 0 || 1 % b);
   9      if (a != 1)
(lldb) si -c 10
Process 565440 stopped
* thread #1, name = 'a.out', stop reason = instruction step into
    frame #0: 0x0000000000401197 a.out`main at small.c:11:3
   8        c = a = (b == 0 || 1 % b);
   9      if (a != 1)
   10       abort();
-> 11     return 0;
   12   }
(lldb) 



$ cat small.c
#include <stdlib.h>
int a, b, c, d[10];

int main() {
  for (int e=0; e<10; e++)
    d[e] = 1;
  if (d[0])
    c = a = (b == 0 || 1 % b);
  if (a != 1)
    abort();
  return 0;
}

--- Comment #1 from Yibiao Yang (杨已彪) <yangyibiao at hust.edu.cn> ---
Created attachment 23535
  --> https://bugs.llvm.org/attachment.cgi?id=23535&action=edit
the binary

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