Search code examples
lldb

LLDB on linux cannot step into function of shared library

I have build lldb from llvm tag 14.0.4 on linux (tested on archlinux latest and centos 7), but it cannot step into function of shared library but gdb could.

This is a minimal example

// main.cpp
#include "mylib.h"

int main(int argc, char *argv[]) {
    add(argc, argc ^ 0xFF);
    add(argc, argc ^ 0xFF);
    return 0;
}


// mylib.h
int add(int a, int b);

// mylib.cpp
int add(int a, int b) {
    return a ^ b & b;
}

The makefile is

all:
    clang++ mylib.cpp -O0 -g3 -shared -fpic -o mylib.so
    clang++ main.cpp -O0 -g3 mylib.so -o main

After building the program, you can use LD_LIBRARY_PATH=. lldb main to load the program into lldb and reproduce the problem with the following steps

  1. b main to set a breakpoint at main function
  2. r to start the program
  3. and now you reached to line add(argc, argc ^ 0xFF);, press s to step into source, but you will get into assemble, a demo output will like
(lldb) s
Process 15758 stopped
* thread #1, name = 'main', stop reason = step in
    frame #0: 0x0000000000400500 main`add(int, int)
main`add:
->  0x400500 <+0>:  jmp    qword ptr [rip + 0x200b22] ; _GLOBAL_OFFSET_TABLE_ + 40
    0x400506 <+6>:  push   0x2
    0x40050b <+11>: jmp    0x4004d0

main`_start:
    0x400510 <+0>:  xor    ebp, ebp

If you use gdb to debug the program, gdb will step you into add function rather than assemble codes.

I have tried lldb on macOS 12.5, it works fine.

Solution

  • This problem was reported to the lldb bug tracker:

    https://github.com/llvm/llvm-project/issues/54250

    It seems to have been a bug in some of the 14.x versions of lldb on Linux, but the originator of that bug said it was fixed in 15.0 and the TOT lldb's.