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rr-debugger

Testing & Quality
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Deterministic debugging with rr record-replay. Use when debugging crashes, ASAN faults, or when reverse execution is needed. Provides reverse-next, reverse-step, reverse-continue commands and crash trace extraction.

QUICK START

How to use this skill

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  1. Open your project in Codex.
  2. Copy the prompt below and paste it into your agent.
  3. Review the proposed files and risks before you approve installation.
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I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/data/rr-debugger/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/rr-debugger/. Do not write files or run scripts until I approve.

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

rr Deterministic Debugger

rr provides deterministic record-replay debugging with full reverse execution capabilities.

Core Workflow

  1. Record: rr record <program> [args]
  2. Replay: rr replay (enters gdb interface with reverse execution)

Reverse Execution Commands

All standard gdb commands work, plus reverse variants:

  • reverse-next / rn: Step back over function calls
  • reverse-step / rs: Step back into functions
  • reverse-continue / rc: Continue backward to previous breakpoint
  • reverse-stepi / rsi: Step back one instruction
  • reverse-nexti / rni: Step back over one instruction

Crash Trace Extraction

Regular Crashes

After rr record <crashing-program>:

rr replay
# In gdb:
reverse-next 100    # Go back 100 steps (adjust N as needed)
# Now step forward to see execution leading to crash:
next
next
...

ASAN Crashes

After rr record <asan-program>:

rr replay
# In gdb:
bt                  # View stack trace
up                  # Issue "up" commands until last app frame (before ASAN runtime)
break *$pc          # Set breakpoint at that location
reverse-continue    # Go back to last app instruction before ASAN
# Now step forward to see execution leading to fault:
next
next
...

Inspecting Variables and Memory

Standard gdb commands work at any point:

  • print <var>: Print variable value
  • print *<ptr>: Dereference pointer
  • x/<format> <address>: Examine memory
    • x/10xb <addr>: 10 bytes in hex
    • x/s <addr>: String at address
  • info locals: Show local variables
  • info args: Show function arguments

Source vs Assembly View

  • list: Show source code around current location
  • disassemble: Show assembly around current location
  • layout src: TUI source view
  • layout asm: TUI assembly view
  • set disassemble-next-line on: Show assembly with each step

Automation Script

Use scripts/crash_trace.py to automatically extract execution trace before crash.