valgrind

name

valgrind

description

Valgrind profiler skill for memory error detection and cache profiling. Use when running Memcheck to find heap corruption, use-after-free, memory leaks, or uninitialised reads; or Cachegrind/Callgrind for cache simulation and function-level profiling. Activates on queries about valgrind, memcheck, heap leaks, use-after-free without sanitizers, cachegrind, callgrind, KCachegrind, or massif memory profiling.

Valgrind

Purpose

Guide agents through Valgrind tools: Memcheck for memory errors, Cachegrind for cache simulation, Callgrind for call graphs, and Massif for heap profiling.

Triggers

• "My program has a memory leak / use-after-free"
• "I can't use ASan — can I use Valgrind instead?"
• "How do I profile cache behaviour without perf?"
• "How do I visualize call graphs with Callgrind?"
• "How do I profile heap allocation patterns?"
• "Valgrind reports errors in third-party code I can't fix"

Workflow

1. Memcheck — memory error detection

Compile with -g -O1 for best results. -O0 is also fine; avoid -O2+ which can produce false positives.

valgrind --tool=memcheck \
         --leak-check=full \
         --show-leak-kinds=all \
         --track-origins=yes \
         --error-exitcode=1 \
         ./prog [args]

Key flags:

Flag	Default	Effect
--leak-check=full	summary	Full leak details
--show-leak-kinds=all	definite	Show all leak kinds