LLVM-EXTRACT(1)

💖 NAME 💖

okay bestie, meet llvm-extract — it extracts a function from an LLVM module. that's the whole gig. it's giving "surgical little scalpel" energy 🔥

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✨ SYNOPSIS ✨

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

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🦋 DESCRIPTION 🦋

so the way llvm-extract works is: you hand it a function name, and it pulls that function out of the LLVM bitcode file you point it at. that's it. slay. 💅

its main character purpose is being a debugging tool — specifically, shrinking big test cases from big programs down to the tiny bit that's actually triggering a bug. like taking a 4-hour video and trimming it to the 3 seconds where the chaos happens. iconic behavior honestly.

and it doesn't stop at just the function, no ma'am. in addition to extracting the bitcode of the specified function, llvm-extract will also remove unreachable global variables, prototypes, and unused types. so it's a whole spring cleaning, not just a pluck-and-go 🧹✨

where does it read from? standard input, if filename is omitted or if filename is -. and the output always goes to standard output — unless you pass the -o option (peep below, it's right there) 💖

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👑 OPTIONS 👑

• --alias alias-name — extract the alias named function-name from the LLVM bitcode. you can pass this multiple times to extract multiple aliases at once. yes queen, stack 'em 🎀
• --ralias alias-regular-expr — extract the alias matching alias-regular-expr from the LLVM bitcode. all aliases matching the regular expression get extracted. may be specified multiple times.
• --bb basic-block-specifier — extract the basic block(s) specified in basic-block-specifier. may be specified multiple times. each <function:bb[;bb]> specifier pair will create a function. lowkey important: if multiple basic blocks are specified in one pair, the first block in the sequence should dominate the rest.
• --delete — delete specified Globals from Module.
• -f — enable binary output on terminals. normally llvm-extract will refuse to write raw bitcode output if the output stream is a terminal. with this option, llvm-extract will write raw bitcode regardless of the output device. it's giving "no thoughts, just vibes" and honestly? valid 🙈
• --func function-name — extract the function named function-name from the LLVM bitcode. may be specified multiple times to extract multiple functions at once. this is the classic, the moment, the reason we're all here 💜
• --rfunc function-regular-expr — extract 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 — extract 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 — extract 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 — preserve the values of constant globals. don't let them get deleted, they're precious 🫶
• --recursive — recursively extract all called functions. it brings the whole friend group along 🌈
• -help — print a summary of command line options. when in doubt, ask the tool itself, bestie 😌
• -o filename — specify the output filename. if filename is - (which is the default), then llvm-extract sends its output to standard output.
• -S — write output in LLVM intermediate language (instead of bitcode). human-readable era ✨

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💀 EXIT STATUS 💀

if llvm-extract succeeds, it will exit with 0. otherwise, if an error occurs, it will exit with a non-zero value. no in-between, no "it's complicated", fr fr.

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🌸 SEE ALSO 🌸

bugpoint(1) <bugpoint.html> — go read it, it's the cousin 🦋

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🎀 AUTHOR 🎀

maintained by the LLVM Team (https://llvm.org/). they're the blueprint, periodt.

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⭐ COPYRIGHT ⭐

2003-2026, LLVM Project

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and that's the whole page, bestie!! this was the LLVM-EXTRACT(1) manual from the LLVM manual set, version 22, dated 2026-07-16. go extract something iconic 💖✨🎀🦋💅