Lldb

mohitmishra786/low-level-dev-skills/skills/debuggers/lldb

作者 mohitmishra786bdc58472fa9f無授權條款253 個星標收錄於 2026年10月9日更新於 2026年10月9日儲存庫3 個月前更新

LLDB debugger skill for C/C++/Swift/Objective-C programs. Use when debugging with LLDB on macOS, FreeBSD, or Linux-clang environments, mapping GDB mental models to LLDB commands, using LLDB in Xcode or VS Code, or debugging Swift/Objective-C. Activates on queries about LLDB commands, GDB to LLDB migration, Apple platform debugging, LLDB Python scripting, or IDE-integrated debugging with clang-built binaries.

僅含說明Software Development

AI 產生的概覽

指導 LLDB 除錯工作階段，並將 GDB 指令對應到 LLDB，適用於 C、C++、Swift 與 Objective-C 程式。

功能: 此技能提供執行 LLDB 除錯工作階段的說明，包括啟動 LLDB、設定中斷點與監看點、檢視變數、記憶體與暫存器，以及管理執行緒。內容包含 GDB 到 LLDB 的指令對照表、Apple/macOS 相關內容（例如 Objective-C 物件列印與 image lookup）、VS Code CodeLLDB 啟動設定，以及 LLDB Python 指令碼範例。它也指向一個包含更完整 GDB-LLDB 指令對照的參考檔案。
適用情境: 適用於使用 LLDB 除錯 C、C++、Swift 或 Objective-C 程式，尤其是在 macOS、FreeBSD 或採用 clang 的 Linux 環境。也適合將既有的 GDB 知識轉換為 LLDB 指令、除錯 Apple 平台程式碼，或在 Xcode 或 VS Code 中設定 LLDB。
執行需求: 不隨附指令碼，僅為說明文件。使用所述工作流程需要 LLDB 除錯器與含除錯資訊的已編譯二進位檔；VS Code 部分假定已安裝 CodeLLDB 擴充套件。

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 <unavailable> for variables"
"How do I use LLDB in VS Code?"
"How do I write an LLDB Python script?"

Workflow

1. Start LLDB

bash

lldb ./prog                         # load binarylldb ./prog -- arg1 arg2            # with argumentslldb -p 12345                       # attach to PIDlldb -c core.1234                   # load core dumplldb ./prog core.1234               # binary + core

lldb ./prog                         # load binarylldb ./prog -- arg1 arg2            # with argumentslldb -p 12345                       # attach to PIDlldb -c core.1234                   # load core dumplldb ./prog core.1234               # binary + core

2. 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`

3. Breakpoints

lldb

# By nameb mainbreakpoint set --name foobreakpoint set --name foo --condition 'x > 0'
# By file:lineb file.c:42breakpoint set --file file.c --line 42
# By addressb -a 0x100003f20
# By regexbreakpoint set --func-regex '^MyClass::'
# Listbreakpoint list / br l
# Deletebreakpoint delete 2
# Disable/enablebreakpoint disable 1breakpoint enable 1
# Commands on hitbreakpoint command add 1  > p x  > continue  > DONE

# By nameb mainbreakpoint set --name foobreakpoint set --name foo --condition 'x > 0'
# By file:lineb file.c:42breakpoint set --file file.c --line 42
# By addressb -a 0x100003f20
# By regexbreakpoint set --func-regex '^MyClass::'
# Listbreakpoint list / br l
# Deletebreakpoint delete 2
# Disable/enablebreakpoint disable 1breakpoint enable 1
# Commands on hitbreakpoint command add 1  > p x  > continue  > DONE

4. Inspect state

lldb

# Print variablep xframe variable xp *ptrp arr[0]
# Print expressionexpression x * 2 + 1expr (int)sqrt(9.0)
# All localsframe variablefr v -a          # include arguments
# Registersregister readregister read rip rsp
# Memorymemory read --size 4 --format x --count 10 0x7fff0000x/10xw 0x7fff0000          # GDB-compatible syntax
# Type infoimage lookup --type MyClasstype lookup MyClass

# Print variablep xframe variable xp *ptrp arr[0]
# Print expressionexpression x * 2 + 1expr (int)sqrt(9.0)
# All localsframe variablefr v -a          # include arguments
# Registersregister readregister read rip rsp
# Memorymemory read --size 4 --format x --count 10 0x7fff0000x/10xw 0x7fff0000          # GDB-compatible syntax
# Type infoimage lookup --type MyClasstype lookup MyClass

5. Watchpoints

lldb

watchpoint set variable x           # write watchpointwatchpoint set variable -w read x   # read watchpointwatchpoint set variable -w read_write xwatchpoint set expression -- &x     # by address
watchpoint listwatchpoint delete 1

watchpoint set variable x           # write watchpointwatchpoint set variable -w read x   # read watchpointwatchpoint set variable -w read_write xwatchpoint set expression -- &x     # by address
watchpoint listwatchpoint delete 1

6. Threads

lldb

thread listthread select 3thread backtrace allthread backtrace --count 5           # limit depth
# Per-thread steppingthread step-over                     # step this thread only

thread listthread select 3thread backtrace allthread backtrace --count 5           # limit depth
# Per-thread steppingthread step-over                     # step this thread only

7. macOS / Apple specifics

lldb

# Symbol lookup in shared cacheimage lookup --address 0x18ab12345image lookup --name objc_msgSend
# Objective-C method breakpointb "-[NSArray objectAtIndex:]"b "+[NSString stringWithFormat:]"
# Inspect Objective-C objectpo myObject                          # print-object (calls -description)po [arr count]
# Show loaded librariesimage listimage list -b                        # brief (names only)

# Symbol lookup in shared cacheimage lookup --address 0x18ab12345image lookup --name objc_msgSend
# Objective-C method breakpointb "-[NSArray objectAtIndex:]"b "+[NSString stringWithFormat:]"
# Inspect Objective-C objectpo myObject                          # print-object (calls -description)po [arr count]
# Show loaded librariesimage listimage list -b                        # brief (names only)

8. VS Code integration

Install the CodeLLDB extension. .vscode/launch.json:

json

{  "version": "0.2.0",  "configurations": [    {      "name": "Debug (lldb)",      "type": "lldb",      "request": "launch",      "program": "${workspaceFolder}/build/prog",      "args": [],      "cwd": "${workspaceFolder}",      "preLaunchTask": "build"    }  ]}

{  "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

python

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')

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 [blocked].

Related skills

Use skills/debuggers/gdb for GDB workflows
Use skills/debuggers/core-dumps for core dump analysis
Use skills/compilers/clang for building with debug info

來源與署名

來源：mohitmishra786/low-level-dev-skills位於skills/debuggers/lldb提交bdc5847

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Lldb

LLDB

Purpose

Triggers

Workflow

1. Start LLDB

2. GDB → LLDB command map

3. Breakpoints

4. Inspect state

5. Watchpoints

6. Threads

7. macOS / Apple specifics

8. VS Code integration

9. LLDB Python scripting

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