Linkers Lto

Solid reference for when you're wrestling with undefined references, trying to enable LTO without breaking your build, or figuring out why your binary is bloated. Covers GNU ld, gold, and lld selection, the left-to-right link order gotcha that bites everyone, and the full LTO setup for both GCC and Clang including ThinLTO. The symbol visibility and --gc-sections sections are especially practical. It won't teach you linker theory, but if you need to know whether to use --start-group or how to generate a map file to debug where your symbols went, it's all here in working examples.

skills.sh installs: 663
GitHub stars: 279
last updated: Aug 21, 2026

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Install

$ npx -y skills add mohitmishra786/low-level-dev-skills --skill linkers-lto --agent claude-code

Installs into .claude/skills of the current project.

Files

Linkers and LTO

Purpose

Guide agents through linker selection, common linker flags, link-order issues, LTO setup, and symbol-visibility management.

Triggers

"I'm getting undefined reference at link time"
"How do I enable LTO for a real project?"
"Which linker should I use: ld, gold, or lld?"
"How do I reduce binary size with --gc-sections?"
"How do I write or understand a linker script?"
"I have duplicate symbol or weak symbol issues"

Workflow

1. Linker selection

Linker	Invocation	Strengths
GNU ld (BFD)	default on Linux	Universal, stable
gold	`-fuse-ld=gold`	Faster than ld for C++; supports LTO plugins
lld (LLVM)	`-fuse-ld=lld`	Fastest, parallel, required for Clang LTO

# Use lld with GCC or Clang
gcc -fuse-ld=lld -o prog ...
clang -fuse-ld=lld -o prog ...

# Check which linker is used
gcc -v -o prog main.c 2>&1 | grep 'Invoking'

2. Essential linker flags

# Pass linker flags via compiler driver:
# -Wl,flag1,flag2   (comma-separated, no spaces)
# -Wl,flag1 -Wl,flag2  (separate -Wl options)

SKILL.md on GitHub

Details

Repository: github.com/mohitmishra786/low-level-dev-skills
First seen: Jun 3, 2026