LLDB Purpose Guide agents through LLDB sessions and map existing GDB knowledge to LLDB. Covers command differences, Apple specifics, Python scripting, and IDE integration. Triggers "I'm on macOS and need to debug a C++ program" "How does LLDB differ from GDB?" "How do I do [GDB command] in LLDB?" "LLDB shows for variables" "How do I use LLDB in VS Code?" "How do I write an LLDB Python script?" Workflow 1. Start LLDB lldb ./prog

load binary

lldb ./prog -- arg1 arg2

with arguments

lldb -p 12345

attach to PID

lldb -c core.1234

load core dump

lldb ./prog core.1234

binary + core

GDB → LLDB command map Source: https://lldb.llvm.org/use/map.html GDB LLDB Notes run [args] process launch [args] / r continue process continue / c next thread step-over / n step thread step-in / s nexti thread step-inst-over / ni stepi thread step-inst / si finish thread step-out / finish break main breakpoint set -n main / b main break file.c:42 breakpoint set -f file.c -l 42 / b file.c:42 break *0x400abc breakpoint set -a 0x400abc / b -a 0x400abc watch x watchpoint set variable x / wa s v x print x frame variable x / p x print/x x p/x x info locals frame variable / fr v info args frame variable --arguments backtrace thread backtrace / bt frame N frame select N / f N info threads thread list thread N thread select N thread apply all bt thread backtrace all x/10wx addr memory read -s4 -fx -c10 addr / x/10xw addr set var = 42 expression var = 42 / expr var = 42 quit quit / q
Breakpoints

By name

b main breakpoint set --name foo breakpoint set --name foo --condition 'x > 0'

By file:line

b file.c:42 breakpoint set --file file.c --line 42

By address

b -a 0x100003f20

By regex

breakpoint set --func-regex '^MyClass::'

List

breakpoint list / br l

Delete

breakpoint delete 2

Disable/enable

breakpoint disable 1 breakpoint enable 1

Commands on hit

breakpoint command add 1

p x continue DONE 4. Inspect state

Print variable

p x frame variable x p *ptr p arr[0]

Print expression

expression x * 2 + 1 expr (int)sqrt(9.0)

All locals

frame variable fr v -a # include arguments

Registers

Memory

memory read --size 4 --format x --count 10 0x7fff0000 x/10xw 0x7fff0000 # GDB-compatible syntax

Type info

image lookup --type MyClass type lookup MyClass 5. Watchpoints watchpoint set variable x # write watchpoint watchpoint set variable -w read x # read watchpoint watchpoint set variable -w read_write x watchpoint set expression -- &x # by address watchpoint list watchpoint delete 1 6. Threads thread list thread select 3 thread backtrace all thread backtrace --count 5 # limit depth

Per-thread stepping

thread step-over # step this thread only 7. macOS / Apple specifics

Symbol lookup in shared cache

image lookup --address 0x18ab12345 image lookup --name objc_msgSend

Objective-C method breakpoint

b "-[NSArray objectAtIndex:]" b "+[NSString stringWithFormat:]"

Inspect Objective-C object

po myObject # print-object (calls -description) po [arr count]

Show loaded libraries

image list image list -b # brief (names only) 8. VS Code integration Install the CodeLLDB extension. .vscode/launch.json : { "version" : "0.2.0" , "configurations" : [ { "name" : "Debug (lldb)" , "type" : "lldb" , "request" : "launch" , "program" : "${workspaceFolder}/build/prog" , "args" : [ ] , "cwd" : "${workspaceFolder}" , "preLaunchTask" : "build" } ] } 9. LLDB Python scripting import lldb def print_all_threads ( debugger , command , result , internal_dict ) : target = debugger . GetSelectedTarget ( ) process = target . GetProcess ( ) for thread in process : print ( f"Thread { thread . GetIndexID ( ) } : { thread . GetName ( ) } " ) for frame in thread : print ( f" { frame } " ) def __lldb_init_module ( debugger , internal_dict ) : debugger . HandleCommand ( 'command script add -f myscript.print_all_threads pthreads' ) Load: command script import /path/to/myscript.py For a full GDB↔LLDB command map, see references/gdb-lldb-map.md .

安装