OPT(1)

✨ OPT(1) — it's giving "the LLVM optimizer" 💅

okay so bestie, pull up a chair, we're talking about opt from the LLVM manual, section 1 (that's the user commands section, iykyk). this is the glow-up page. let's get into it 🫶

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🌸 NAME 🌸

opt — the LLVM optimizer. literally what it says on the tin, no cap. ✨

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🦋 SYNOPSIS 🦋

opt [options] [filename]

that's it. that's the whole vibe. ✨

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💖 DESCRIPTION 💖

okay so opt is the modular LLVM optimizer and analyzer 👑. here's the tea:

• it takes LLVM source files as input 🍓
• it runs the optimizations or analyses you told it to run on them 🔥
• then it outputs the optimized file 💅

and here's the part that gets people: the optimizations available via opt depend upon what libraries were linked into it, as well as any additional libraries that have been loaded with the -load option. so like, it's not a fixed menu, it's a build-your-own-sundae situation 🍨. to find out what optimizations you can actually use, hit up the -help option. periodt.

now, about input 📥: if filename is omitted from the command line, or is "-", then opt reads its input from standard input. flexible queen 💅.

inputs can be in either of these formats, and yes you can mix and match, she doesn't judge:

• LLVM assembly language format (.ll) 📝
• LLVM bitcode format (.bc) 🧊

and for output 📤: if you don't specify an output filename with the -o option, opt writes its output to the standard output. so like, if you don't tell her where to put it, she's just gonna yell it at your terminal. iconic honestly 🌈.

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🎀 OPTIONS 🎀

here come the flags, bestie. every single one. buckle up 🦋

• -f — Enable binary output on terminals. normally opt will refuse to write raw bitcode output if the output stream is a terminal (she's polite like that 🙈). with this option, opt will write raw bitcode regardless of the output device. so yeah, this is the "i know what i'm doing, let me cook" flag 💀.
• -help — print a summary of command line options. your bestie for figuring out what's even available ✨.
• -o <filename> — specify the output filename. that's the whole thing. where the output goes 📤.
• -S — write output in LLVM intermediate language (instead of bitcode). the "give me the readable stuff please" flag 📝.
• -{passname} — okay this one is lowkey the main character 👑. opt provides the ability to run any of LLVM's optimization or analysis passes in any order. the -help option lists all the passes available. and here's the crucial bit: the order in which the options occur on the command line are the order in which they are executed (within pass constraints). so the order you type them = the order they run. sequencing matters, bestie, no cap 🫶.
• -strip-debug — this option causes opt to strip debug information from the module before applying other optimizations. it's essentially the same as -strip, but it ensures that stripping of debug information is done first. order matters, we love a priority queen 💅.
• -verify-each — this option causes opt to add a verify pass after every pass otherwise specified on the command line (including -verify). super useful when you suspect a pass is creating an invalid module but it's not clear which pass is doing it — she snitches on the culprit 🔍.
• -stats — print statistics. numbers! data! 📊
• -time-passes — record the amount of time needed for each pass and print it to standard error ⏱️.
• -debug — if this is a debug build, this option will enable debug printouts from passes which use the LLVM_DEBUG() macro. see the LLVM Programmer's Manual, section #DEBUG for more information 🐛.
• -load=<plugin> — load the dynamic object plugin. this object should register new optimization or analysis passes. once loaded, the object will add new command line options to enable various optimizations or analyses ✨. to see the new complete list of optimizations, use the -help and -load options together. for example:

opt -load=plugin.so -help

• -print-passes — print all available passes and exit. she shows you the menu and then immediately leaves 🚪💨.

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💀 EXIT STATUS 💀

• if opt succeeds, it will exit with 0. we love a clean win 🎉
• otherwise, if an error occurs, it will exit with a non-zero value. something went wrong, bestie 😭

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🫶 AUTHOR 🫶

maintained by the LLVM Team (<https://llvm.org/>). they're the ones keeping this whole thing running, respect 👑

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⭐ COPYRIGHT ⭐

2003-2025, LLVM Project 🌈

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okay that's the whole page bestie, you ate that reading 🎀 and just so you know, this page is from the LLVM source, dated 2025-09-03 💅 go forth and optimize, no cap 💖✨🦋