LLVM-EXTRACT(1)

💅 LLVM-EXTRACT(1) 💅

okay so bestie, welcome to the LLVM manual page for llvm-extract, and no cap this one is actually such a useful little tool once you get it. grab a strawberry 🍓 and let's go.

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✨ NAME ✨

llvm-extract — extract a function from an LLVM module. literally that's the whole vibe, it pulls a function out. 🫶

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🌈 SYNOPSIS 🌈

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

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🦋 DESCRIPTION 🦋

so the llvm-extract command takes the name of a function and extracts it from the specified LLVM bitcode file. that's it, that's the job. 💅

it's primarily used as a debugging tool to reduce test cases from larger programs that are triggering a bug. like, you've got this giant messy program and one tiny function is acting up — you don't need the whole thing, you just need the culprit. main character energy honestly. 👑

and it's not just a copy-paste situation either: 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 doing the cleanup too. icon. ✨

it reads its input from standard input if filename is omitted or if filename is -. and the output is always written to standard output, unless the -o option is specified (peep below, i got you). 💖

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🎀 OPTIONS 🎀

• --alias alias-name — extract the alias named function-name from the LLVM bitcode. may be specified multiple times to extract multiple alias at once. (yes bestie, "multiple alias", that's what it says, i don't make the rules 🙈)
• --ralias alias-regular-expr — extract the alias matching alias-regular-expr from the LLVM bitcode. all alias matching the regular expression will be extracted. may be specified multiple times. regex girlies rise 🔥
• --bb basic-block-specifier — extract basic block(s) specified in basic-block-specifier. may be specified multiple times. each <function:bb[;bb]> specifier pair will create a function. if multiple basic blocks are specified in one pair, the first block in the sequence should dominate the rest. lowkey important, don't sleep on the dominance thing 💀
• --delete — delete specified Globals from Module. yep, it's giving destruction. 🫶
• -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. no vibe check, no safety net. 😭
• --func function-name — extract the function named function-name from the LLVM bitcode. may be specified multiple times to extract multiple functions at once. the classic. ⭐
• --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. globals deserve love too 💜
• --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. (note it says global-regular-expr in the description while the flag is --rglob — that's just how it's written, i'm not touching it 🙈)
• --keep-const-init — preserve the values of constant globals. keep the constants, bestie, they're precious. 💖
• --recursive — recursively extract all called functions. it goes deep. it goes all the way down. 🌀
• -help — print a summary of command line options. when in doubt, ask for help, that's growth 🌸
• -o filename — specify the output filename. if filename is - (the default), then llvm-extract sends its output to standard output. so yeah, - is the default, no -o needed if you're happy with stdout 🎀
• -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. simple as that, no plot twist 🫶

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🌸 SEE ALSO 🌸

• llvm-reduce(1) <llvm-reduce.html> — its sibling, its bestie, its partner in crime 💜

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👑 Author 👑

maintained by the LLVM Team (https://llvm.org/). they're iconic for this, fr fr. 🧚

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🎀 Copyright 🎀

2003-2026, LLVM Project — that's a long reign, periodt. 👑

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okay that's the whole page bestie, mwah 💋 — this was page revision 23, dated 2026-10-20, and it's the LLVM-EXTRACT(1) manual. go extract something cute! 🦋✨