gcc

name

gcc

description

GCC compiler skill for C/C++ projects. Use when selecting optimization levels, warning flags, debug builds, LTO, sanitizer instrumentation, or diagnosing compilation errors with GCC. Covers flag selection for debug vs release, ABI concerns, preprocessor macros, profile-guided optimization, and integration with build systems. Activates on queries about gcc flags, compilation errors, performance tuning, warning suppression, or cross-standard compilation.

GCC

Purpose

Guide agents through GCC invocation: flag selection, build modes, warning triage, PGO, LTO, and common error patterns. Assume the project uses GNU Make, CMake, or a shell script.

Triggers

• "What flags should I use for a release build?"
• "GCC is giving me a warning/error I don't understand"
• "How do I enable LTO / PGO with GCC?"
• "How do I compile with -fsanitize?"
• "My binary is too large / too slow"
• Undefined reference errors, ABI mismatch, missing symbols

Workflow

1. Choose a build mode

Goal	Recommended flags
Debug	-g -O0 -Wall -Wextra
Debug + debuggable optimisation	-g -Og -Wall -Wextra
Release	-O2 -DNDEBUG -Wall
Release (max perf, native only)	-O3 -march=native -DNDEBUG
Release (min size)	-Os -DNDEBUG
Sanitizer (dev)	-g -O1 -fsanitize=address,undefined

Always pass -std=c11 / -std=c++17 (or the required standard) explicitly. Never rely on the implicit default.