LLVM-NM(1)

📦
version 12.0.1 · 4 versions
, in fedora 43, fedora 44

💅 LLVM-NM(1) — the symbol tea, served hot

okay bestie, welcome to llvm-nm, straight out of the LLVM manual. it's a whole vibe and it's genuinely useful, i promise. let's get into it 🫶

✨ NAME ✨

llvm-nm — list LLVM bitcode and object file's symbol table. that's the job. that's the whole assignment. 👑

🌸 SYNOPSIS 🌸

llvm-nm [options] [filenames...]

🦋 DESCRIPTION 🦋

so llvm-nm lists the names of symbols from LLVM bitcode files, object files, and archives. each symbol gets listed along with some simple info about where it came from. it's giving detective energy, fr fr. 🔍

if you don't specify any filename, a.out is the input. iconic default behavior, honestly. and if you use - as a filename, llvm-nm will read a file from its standard input stream. very flexible of it 💅

llvm-nm's default output format is the traditional BSD nm output format. each such output record is made of:

  • an (optional) 8-digit hexadecimal address
  • a type code character
  • a name

...for each symbol. one record gets printed per line, and fields are separated by spaces. when the address is omitted, it's replaced by 8 spaces. yes, eight. not zero. eight. count them if you must 😭

🎀 the type code characters (aka the alphabet of symbols)

where both lower and upper-case characters are listed for the same meaning: a lower-case character = a local symbol, and an upper-case character = a global (external) symbol. no cap.

  • a, A — Absolute symbol.
  • b, B — Uninitialized data (bss) object.
  • C — Common symbol. Multiple definitions link together into one definition.
  • d, D — Writable data object.
  • i, I — COFF: .idata symbol or symbol in a section with IMAGE_SCN_LNK_INFO set.
  • n — ELF: local symbol from non-alloc section. COFF: debug symbol.
  • N — ELF: debug section symbol, or global symbol from non-alloc section.
  • s, S — COFF: section symbol. Mach-O: absolute symbol or symbol from a section other than __TEXT_EXEC __text, __TEXT __text, __DATA __data, or __DATA __bss.
  • r, R — Read-only data object.
  • t, T — Code (text) object.
  • u — ELF: GNU unique symbol.
  • U — Named object is undefined in this file.
  • v — ELF: Undefined weak object. It is not a link failure if the object is not defined.
  • V — ELF: Defined weak object symbol. This definition will only be used if no regular definitions exist in a link. If multiple weak definitions and no regular definitions exist, one of the weak definitions will be used.
  • w — Undefined weak symbol other than an ELF object symbol. It is not a link failure if the symbol is not defined.
  • W — Defined weak symbol other than an ELF object symbol. This definition will only be used if no regular definitions exist in a link. If multiple weak definitions and no regular definitions exist, one of the weak definitions will be used.
  • - — Mach-O: N_STAB symbol.
  • ? — Something unrecognizable. (mystery symbol, we love an enigma 🕵️)
lowkey important: because LLVM bitcode files typically contain objects that are not considered to have addresses until they are linked into an executable image or dynamically compiled "just-in-time", llvm-nm does not print an address for any symbol in an LLVM bitcode file — even symbols which are defined in the bitcode file. so no address, no drama, that's just how it is 💀

✨ OPTIONS ✨

one bullet per option bestie, we're being thorough. 🧚

  • -B — Use BSD output format. Alias for --format=bsd.
  • --debug-syms, -a — Show all symbols, even those usually suppressed.
  • --defined-only, -U — Print only symbols defined in this file.
  • --demangle, -C — Demangle symbol names.
  • --dynamic, -D — Display dynamic symbols instead of normal symbols.
  • --extern-only, -g — Print only symbols whose definitions are external; that is, accessible from other files.
  • --format=<format>, -f — Select an output format; format may be sysv, posix, darwin, or bsd. The default is bsd.
  • --help, -h — Print a summary of command-line options and their meanings.
  • --help-list — Print an uncategorized summary of command-line options and their meanings.
  • --just-symbol-name, -j — Print just the symbol names.
  • -m — Use Darwin format. Alias for --format=darwin.
  • --no-demangle — Don't demangle symbol names. This is the default.
  • --no-llvm-bc — Disable the LLVM bitcode reader.
  • --no-sort, -p — Show symbols in the order encountered.
  • --no-weak, -W — Don't print weak symbols.
  • --numeric-sort, -n, -v — Sort symbols by address.
  • --portability, -P — Use POSIX.2 output format. Alias for --format=posix.
  • --print-armap, -M — Print the archive symbol table, in addition to the symbols.
  • --print-file-name, -A, -o — Precede each symbol with the file it came from.
  • --print-size, -S — Show symbol size as well as address (not applicable for Mach-O).
  • --radix=<RADIX>, -t — Specify the radix of the symbol address(es). Values accepted are d (decimal), x (hexadecimal) and o (octal).
  • --reverse-sort, -r — Sort symbols in reverse order.
  • --size-sort — Sort symbols by size.
  • --special-syms — Do not filter special symbols from the output.
  • --undefined-only, -u — Print only undefined symbols.
  • --version — Display the version of the llvm-nm executable. Does not stack with other commands.
  • --without-aliases — Exclude aliases from the output.
  • @<FILE> — Read command-line options from response file <FILE>.

🌈 MACH-O SPECIFIC OPTIONS 🌈

apple kids, this section is for you. 🍓

  • --add-dyldinfo — Add symbols from the dyldinfo, if they are not already in the symbol table. This is the default.
  • --add-inlinedinfo — Add symbols from the inlined libraries, TBD file inputs only.
  • --arch=<arch1[,arch2,...]> — Dump the symbols from the specified architecture(s).
  • --dyldinfo-only — Dump only symbols from the dyldinfo.
  • --no-dyldinfo — Do not add any symbols from the dyldinfo.
  • -s=<segment section> — Dump only symbols from this segment and section name.
  • -x — Print symbol entry in hex.

💀 BUGS 💀

not everything is perfect, bestie, and honesty is the vibe:

  • llvm-nm does not support the full set of arguments that GNU nm does.
so if you're coming from GNU nm expecting every single flag to be there... it's not. we said what we said 🙈

🫶 EXIT STATUS 🫶

llvm-nm exits with an exit code of zero.

that's it. that's the exit status. zero. clean. no crumbs. ✨

👑 SEE ALSO 👑

go read these too, they're the friend group:

💜 AUTHOR 💜

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

2003-2024, LLVM Project

okay that's the whole page!! 💖 this was LLVM, dated 2024-07-18, page version 12. mwah, go list some symbols, you're gonna slay 🎀✨🦋

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