LLVM-EXTRACT(1)

🌸 NAME 🌸

llvm-extract — grab a single function out of an LLVM module, no cap 💅

So bestie, you found your way into the LLVM-EXTRACT(1) page of the LLVM manual — section 1, the real one, the command-line one 🫶. This is the tool you call when a giant program is doing something cursed and you just want the one little function that's misbehaving.

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✨ SYNOPSIS ✨

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

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🦋 DESCRIPTION 🦋

okay so here's the tea, bestie ☕. llvm-extract takes the name of a function and pulls it out of whatever LLVM bitcode file you point it at. That's the whole vibe.

It's mainly a debugging tool, and its main character moment is reducing test cases — like, you've got a massive program that's triggering a bug, and you want to shrink it down to just the guilty little function so you can actually look at it without your brain melting 😭. It's giving lab scientist with tiny tweezers 🧚.

And it doesn't stop at just copying the function out — it also sweeps away the stuff nobody needs anymore:

• unreachable global variables 🧹
• prototypes 🧹
• unused types 🧹

Where does it read from? If you skip filename entirely, or if you pass filename as -, it reads its input from standard input. And where does the output go? Always to standard output, unless you say otherwise with the -o option (peep the OPTIONS section below, it's right there 👀).

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👑 OPTIONS 👑

Every single one, in order, no skips, periodt 💖

• –alias alias-name — Extract the alias named function-name from the LLVM bitcode. You can hit this one more than once to extract multiple aliases at the same time. (And yes, the page literally says function-name in this one's description, we're not editing the queen's words 💀)
• –ralias alias-regular-expr — Extract the alias matching alias-regular-expr from the LLVM bitcode. All aliases matching that 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. And if you list multiple basic blocks inside 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.
• –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 one you'll be typing the most, fr fr.
• –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. Regex girlies, this one's for you 🎀.
• –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 dropped, bestie 🫶.
• –recursive — Recursively extract all called functions. It's giving "bring the whole friend group" energy 🌈.
• -help — Print a summary of command line options.
• -o filename — Specify the output filename. If filename 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 😭.

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⭐ SEE ALSO ⭐

• bugpoint(1)

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💜 AUTHOR 💜

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

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🎀 COPYRIGHT 🎀

2003-2024, LLVM Project

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and that's the whole page, bestie — go extract something iconic 💅✨🦋

tiny sign-off: this whole thing lives in the LLVM manual, version 15, dated 2024-04-14, filed under LLVM-EXTRACT(1). mwah 🫶