LLVM-NM(1)

📦
version 13.0.1 · 5 versions
, in ubuntu jammy

💅 LLVM-NM 💅

okay bestie, real talk: this is the llvm-nm page from the LLVM manual, and we're gonna make it make sense. it lists symbol tables. that's the whole gig. let's go 🎀

✨ NAME ✨

llvm-nm — list LLVM bitcode and object file's symbol table

✨ SYNOPSIS ✨

llvm-nm [options] [filenames…]

✨ DESCRIPTION ✨

so the llvm-nm utility lists the names of symbols from LLVM bitcode files, object files, and archives — like, it goes through and tells you every symbol living in there. each symbol gets listed along with some simple info about its provenance, iykyk. 🕵️

no filename? no problem — a.out is used as the input. and if you use - as a filename, llvm-nm will read a file from its standard input stream. iconic behavior honestly.

llvm-nm's default output format is the traditional BSD nm output format. each one of those output records is made of an (optional) 8-digit hexadecimal address, then a type code character, then a name — for each symbol. one record printed per line, fields separated by spaces. and when the address is omitted, it gets replaced by 8 spaces. yes, spaces. the vibes are preserved. 💅

here are the supported type code characters, babes. where both lower and upper-case characters are listed for the same meaning: a lower-case character represents a local symbol, whilst an upper-case character represents a global (external) symbol. ✨

  • 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. 😭

okay and this next bit is 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. no address. none. periodt. 💀

✨ OPTIONS ✨

  • -B — Use BSD output format. Alias for --format=bsd.
  • --debug-syms, -a — Show all symbols, even those usually suppressed. 👀
  • --defined-only — Print only symbols defined in this file.
  • --demangle, -C — Demangle symbol names. make 'em readable bestie.
  • --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, bsd or just-symbols. The default is bsd.
  • --help, -h — Print a summary of command-line options and their meanings.
  • -j — Print just the symbol names. Alias for --format=just-symbols.
  • -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 — 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 — 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).
  • --quiet — Suppress 'no symbols' diagnostic. 🤫
  • --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, -V — Display the version of the llvm-nm executable, then exit. Does not stack with other commands. ⚠️
  • @<FILE> — Read command-line options from response file <FILE>.

🍎 MACH-O SPECIFIC OPTIONS 🍎

these ones are only for the Apple-heads, bestie. 🦋

  • --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 😭

  • llvm-nm does not support the full set of arguments that GNU nm does. not me finding out the hard way 🙈

🌈 EXIT STATUS 🌈

llvm-nm exits with an exit code of zero. that's it. that's the status. slay. ✨

👀 SEE ALSO 👀

llvm-ar(1), llvm-objdump(1), llvm-readelf(1), llvm-readobj(1)

💖 AUTHOR 💖

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

2003-2023, LLVM Project

okay and that's the whole thing, bestie — this page comes from the LLVM manual, source 13, dated 2023-07-14. go forth and read those symbol tables 💅🫶🌸

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