Software debugger
The LLDB Debugger (LLDB) is the debugger component of the LLVM project. It is built as a set of reusable components which extensively use existing libraries from LLVM, such as the Clang expression parser and LLVM disassembler. LLDB is free and open-source software under the University of Illinois/NCSA Open Source License, a BSD-style permissive software license. Since v9.0.0, it was relicensed to the Apache License 2.0 with LLVM Exceptions.
Current state.
LLDB supports debugging of programs written in C, Objective-C, and C++. The Swift community maintains a version which adds support for the language. Free Pascal and the Lazarus IDE can use LLDB as backend for their own FpDebug engine. 
The LLDB debugger is known to work on macOS, Linux, FreeBSD, NetBSD and Windows, and supports i386, x86-64, and ARM instruction sets. LLDB is the default debugger for Xcode 5 and later. Android Studio also uses LLDB for debug. LLDB can be used from other IDEs, including Visual Studio Code, C++Builder, Eclipse, and CLion.
An example session.
Consider the following incorrect program written in C:
int main(void)
 char msg = "Hello, world!\n";
 printf("%s", msg);
 return 0;
Using the clang compiler on macOS, the code above can be compiled using the codice_1 flag to include appropriate debug information on the binary generated—including the source code—making it easier to inspect it using LLDB. Assuming that the file containing the code above is named codice_2, the command for the compilation could be:
$ clang -Wno-error=int-conversion -g test.c -o test
And the binary can now be run:
$ ./test
Segmentation fault
Since the example code, when executed, generates a segmentation fault, lldb can be used to inspect the problem:
$ lldb test
(lldb) target create "test"
Current executable set to 'test' (x86_64).
(lldb) run
Process 70716 launched: '/Users/wikipedia/test' (x86_64)
Process 70716 stopped
 frame #0: 0x00007fff6c7c46f2 libsystem_platform.dylib`_platform_strlen + 18
libsystem_platform.dylib`_platform_strlen:
- ; 0x7fff6c7c46f2 ;+18 ;: pcmpeqb xmm0, xmmword ptr [rdi]
 0x7fff6c7c46f6 ;+22 ;: pmovmskb esi, xmm0
 0x7fff6c7c46fa ;+26 ;: and rcx, 0xf
 0x7fff6c7c46fe ;+30 ;: or rax, -0x1
Target 0: (test) stopped.
The problem occurs when calling the function codice_3, but we can run a backtrace to identify the exact line of code that is causing the problem:
(lldb) bt
 * frame #0: 0x00007fff6c7c46f2 libsystem_platform.dylib`_platform_strlen + 18
 frame #1: 0x00007fff6c66b16a libsystem_c.dylib`__vfprintf + 8812
 frame #2: 0x00007fff6c6911c3 libsystem_c.dylib`__v2printf + 475
 frame #3: 0x00007fff6c668e22 libsystem_c.dylib`vfprintf_l + 54
 frame #4: 0x00007fff6c666f72 libsystem_c.dylib`printf + 174
 frame #5: 0x0000000100000f6d test`main at test.c:5:2
 frame #6: 0x00007fff6c5dc3d5 libdyld.dylib`start + 1
(lldb) source list
 3 int main(void) {
 4 char msg = "Hello, world!\n";
 5 printf("%s", msg);
 6 return 0;
From the line beginning with codice_4, LLDB indicates that the error is at line 5 of codice_2. Running codice_6, we see that this refers to the call to codice_7. According to the exception code codice_8 from the backtrace, codice_3 is trying to read from a region of memory it does not have access to by dereferencing an invalid pointer. Returning to the source code, we see that the variable codice_10 is of type codice_11 but contains a string instead of a character. To fix the problem, we modify the code to indicate that codice_10 is a "pointer" to a string of codice_13 by adding the codice_14 operator:
int main(void)
 char* msg = "Hello, world!\n";
 printf("%s", msg);
 return 0;
After recompiling and running the executable again, LLDB now gives the correct result:
(lldb) target create "test"
Current executable set to 'test' (x86_64).
(lldb) run
Process 93319 launched: '/Users/wikipedia/test' (x86_64)
Hello, world!
Process 93319 exited with status = 0 (0x00000000)
LLDB runs the program, which prints the output of codice_7 to the screen. After the program exits normally, LLDB indicates that the process running the program has completed, and prints its exit status.
References.
 ;templatestyles src="Reflist/styles.css" / ;