LLVM-EXTRACT(1)

💅 LLVM-EXTRACT — okay bestie, let me put you on

So this is a page from the LLVM manual set — like, the LLVM-EXTRACT(1) one specifically, section 1, tools-and-commands territory. Sit down, grab a strawberry drink 🍓, and let's get into it.

✨ NAME ✨

llvm-extract — literally just pulls one function out of an LLVM module. That's the whole vibe. 🫶

✨ SYNOPSIS ✨

llvm-extract [options] --func function-name [filename]

✨ DESCRIPTION ✨

Okay so here's the tea ☕: llvm-extract takes a function name and extracts it out of the LLVM bitcode file you point it at. Its main-character purpose in life? Debugging 💀 — specifically shrinking big test cases down from larger programs that are triggering a bug. Think of it as the "reduce the noise until the bug is the only thing left" tool. Iconic behavior honestly.

And it doesn't stop at just the function — no cap, it will also remove unreachable global variables, prototypes, and unused types. Spring cleaning energy 🧹✨.

Where does it read from? Standard input, if filename is omitted or if filename is -. Ngl, that's convenient. And the output? Always goes to standard output — unless you use the -o option (peep below 👀).

✨ OPTIONS ✨

• --alias alias-name — extracts the alias named function-name from the LLVM bitcode. You can pass it multiple times to extract multiple alias at once. 🎀
• --ralias alias-regular-expr — extracts the alias matching alias-regular-expr from the LLVM bitcode. Every alias that matches the regular expression gets extracted. May be specified multiple times.
• --bb basic-block-specifier — extracts the basic block(s) named in basic-block-specifier. May be specified multiple times. Each <function:bb[;bb]> specifier pair will create a function. Heads up ⚠️: if you specify multiple basic blocks in one pair, the first block in the sequence should dominate the rest.
• --delete — deletes specified Globals from Module. 🗑️
• -f — enables binary output on terminals. Normally llvm-extract will refuse to write raw bitcode output if the output stream is a terminal. With this option, it'll write raw bitcode regardless of the output device. (Lowkey a "commit to it" flag 💀)
• --func function-name — extracts the function named function-name from the LLVM bitcode. May be specified multiple times to extract multiple functions at once. This is the one your synopsis is obsessed with.
• --rfunc function-regular-expr — extracts the function(s) matching function-regular-expr from the LLVM bitcode. All functions matching the regular expression will be extracted. May be specified multiple times.
• --glob global-name — extracts the global variable named global-name from the LLVM bitcode. May be specified multiple times to extract multiple global variables at once.
• --rglob glob-regular-expr — extracts the global variable(s) matching global-regular-expr from the LLVM bitcode. All global variables matching the regular expression will be extracted. May be specified multiple times.
• --keep-const-init — preserves the values of constant globals. 🫶 don't lose the data bestie
• --recursive — recursively extracts all called functions. It's giving "and bring your friends" energy 🌈
• -help — prints a summary of command line options.
• -o filename — specifies the output filename. If filename is - (the default), then llvm-extract sends its output to standard output. 🎯
• -S — writes output in LLVM intermediate language (instead of bitcode). Honestly the more readable option, iykyk.

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✨ EXIT STATUS ✨

If llvm-extract succeeds, it exits with 0. Slay. 💖 Otherwise, if an error occurs, it exits with a non-zero value. 😭

✨ SEE ALSO ✨

• bugpoint(1) <bugpoint.html> — go say hi, it's in the same friend group 🦋

✨ Author ✨

Maintained by the LLVM Team (https://llvm.org/). Kings 👑

✨ Copyright ✨

2003-2026, LLVM Project

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That's the whole page, no crumbs left behind. Every flag, every path, every default preserved 💅

Okay that's a wrap bestie — this one's straight from the LLVM corner of the manual set, dated 2026-05-15, page 21 energy, and you absolutely ate that read-through. 🎀✨🦋💜