rg-optimized

name: rg-optimized description: >- Upgrade an already-installed ripgrep to a from-source build with PCRE2, native CPU SIMD (AVX2 etc.), and fat LTO. Use when the user has stock rg but needs PCRE2 features (lookahead, lookbehind, possessive quantifiers, atomic groups via rg -P), sees "PCRE2 is not available", wants faster ripgrep via target-cpu=native + release-lto, or is building ripgrep from master with all features. NOT for installing rg from scratch.

Optimized ripgrep Build Guide

Why: Stock ripgrep lacks PCRE2. Build from master with all features for -P regex support, lookahead/lookbehind, and native CPU optimizations.

Quick Build (Copy-Paste)

# 1. Install PCRE2 dev libs
sudo apt-get update && sudo apt-get install -y libpcre2-dev pkg-config

# 2. Clone and build
git clone --depth 1 https://github.com/BurntSushi/ripgrep.git /tmp/rg-build
cd /tmp/rg-build
RUSTFLAGS="-C target-cpu=native" cargo +nightly build --profile release-lto --features pcre2

# 3. Find and install
RG_BIN=$(cargo metadata --format-version 1 | grep -o '"target_directory":"[^"]*"' | cut -d'"' -f4)/release-lto/rg
cp "$RG_BIN" ~/.cargo/bin/rg

# 4. Verify
rg --version  # Should show: features:+pcre2

Decision Tree

rg -P pattern fails?
├─ "PCRE2 is not available" → BUILD (this skill)
├─ Pattern syntax error → Check PCRE2 syntax (not Rust regex)
└─ Works fine → No action needed

Need lookahead/lookbehind?
├─ Yes → Need PCRE2 build
└─ No → Stock rg is fine

Want maximum performance?
├─ Native CPU optimizations → Use release-lto + target-cpu=native
└─ Portable binary → Skip target-cpu=native

Build Options Matrix

Profiles (from Cargo.toml)

[profile.release-lto]
inherits = "release"
opt-level = 3
debug = "none"
strip = "symbols"
debug-assertions = false
overflow-checks = false
lto = "fat"
panic = "abort"
incremental = false
codegen-units = 1

Prerequisites

System Dependencies

Rust Toolchain

# Ensure nightly is installed
rustup install nightly
rustup update nightly

# Verify
rustc +nightly --version  # Should be 1.85+

Target Directory Discovery

ripgrep may use a custom target directory (e.g., /tmp/cargo-target for remote compilation). Always discover it:

cd /path/to/ripgrep-source
TARGET_DIR=$(cargo metadata --format-version 1 | grep -o '"target_directory":"[^"]*"' | cut -d'"' -f4)
echo "Binary at: $TARGET_DIR/release-lto/rg"

Installation Locations

Install Command

# Replace existing (may need to rm first if "Text file busy")
rm -f ~/.cargo/bin/rg
cp "$TARGET_DIR/release-lto/rg" ~/.cargo/bin/rg
chmod +x ~/.cargo/bin/rg

Verification

rg --version

Expected output:

ripgrep 15.1.0 (rev XXXXXXXX)

features:+pcre2
simd(compile):+SSE2,+SSSE3,+AVX2
simd(runtime):+SSE2,+SSSE3,+AVX2

PCRE2 10.XX is available (JIT is available)

Key indicators:

• features:+pcre2 — PCRE2 enabled
• simd(compile):+SSE2,+SSSE3,+AVX2 — Native optimizations
• PCRE2 X.XX is available (JIT is available) — Full PCRE2 with JIT

PCRE2 Usage Examples

# Lookahead: lines with 'foo' followed by 'bar' (not necessarily adjacent)
rg -P 'foo(?=.*bar)' file.txt

# Lookbehind: numbers preceded by '$'
rg -P '(?<=\$)\d+' file.txt

# Unicode property: em-dashes
rg -P '[\x{2014}]' file.txt

# Backreferences: repeated words
rg -P '\b(\w+)\s+\1\b' file.txt

# Atomic groups: possessive matching
rg -P '(?>a+)b' file.txt

Troubleshooting

Common Build Errors

pkg-config not found:

sudo apt-get install pkg-config

PCRE2 headers missing:

# Ubuntu/Debian
sudo apt-get install libpcre2-dev

# The -dev package contains headers needed for compilation

Cleanup

rm -rf /tmp/rg-build

References

Anti-Patterns