LLI(1)

📦
version 11.1.0 · 3 versions
, in fedora 43, fedora 44

💖 LLI — the lli(1) page, but make it make sense 💖

okay bestie, gather round, because today we're talking about lli, and she's from the LLVM family, and she is iconic. this is section 1 of the manual, and yes, she ate. 🎀

✨ NAME ✨

lli — directly execute programs from LLVM bitcode. that's it, that's the whole job description. no notes. 💅

🌸 SYNOPSIS 🌸

lli [options] [filename] [program args]

look at her. so simple. so powerful. 🦋

🧚 DESCRIPTION 🧚

so lli directly executes programs in LLVM bitcode format. like, you hand her a program written in LLVM bitcode and she runs it — either through a just-in-time compiler or through an interpreter. two paths, one slay. ✨

and listen, because this part matters: lli is not an emulator. she will not execute IR of different architectures, and she can only interpret (or JIT-compile) for the host architecture. no cap. if you were hoping she'd cosplay as some other CPU, she will not, and honestly? respect the boundaries. 💀

the JIT compiler takes the same arguments as other tools, like llc, but heads up — they don't necessarily work for the interpreter. iykyk. 😭

if filename is not specified, then lli reads the LLVM bitcode for the program from standard input. so you can just pipe it in. main character energy. 🫶

and the optional args you put on the command line? those get passed to the program as arguments. giving "here's your snacks, go be great." 🍓

✨ GENERAL OPTIONS ✨

the everyday fits. the basics. the essentials. 👑

  • -fake-argv0=executable — override the argv[0] value that gets passed into the executing program. yes, she can lie about her name, and it's fine, it's for science. 🙈
  • -force-interpreter={false,true} — if you set this to true, she'll use the interpreter even if a just-in-time compiler is available for this architecture. it defaults to false. so by default she's JIT-ing like normal. 🌈
  • -help — prints a summary of command line options. when in doubt, ask for help, we love a girl who asks for help. 🫶
  • -load=pluginfilename — causes lli to load the plugin (shared object) named pluginfilename and use it for optimization. plug her in. 🔌✨
  • -stats — print statistics from the code-generation passes. at present, this is only meaningful for the just-in-time compiler. noted. 📊
  • -time-passes — record the amount of time needed for each code-generation pass and print it to standard error. clocking the tea. ⏱️
  • -version — print out the version of lli and exit without doing anything else. she said "here's my ID, bye." 💅

🎯 TARGET OPTIONS 🎯

picking who she's performing for. choose wisely, bestie, this is highkey important. 👀

  • -mtriple=target triple — override the target triple specified in the input bitcode file with the specified string. ⚠️ this may result in a crash if you pick an architecture which is not compatible with the current system. so like, don't. or do, and then don't be surprised. 💀
  • -march=arch — specify the architecture for which to generate assembly, overriding the target encoded in the bitcode file. see the output of llc -help for a list of valid architectures. by default this is inferred from the target triple or autodetected to the current architecture. 🧭
  • -mcpu=cpuname — specify a specific chip in the current architecture to generate code for. by default this is inferred from the target triple and autodetected to the current architecture. for a list of available CPUs, use:
llvm-as < /dev/null | llc -march=xyz -mcpu=help

👑

  • -mattr=a1,+a2,-a3,... — override or control specific attributes of the target, like whether SIMD operations are enabled or not. the default set of attributes is set by the current CPU. for a list of available attributes, use:
llvm-as < /dev/null | llc -march=xyz -mattr=help

⭐

🌊 FLOATING POINT OPTIONS 🌊

the floaty girlies. math but make it ✨choices✨. be careful, some of these are giving "chaos". 🌸

  • -disable-excess-fp-precision — disable optimizations that may increase floating point precision. 💅
  • -enable-no-infs-fp-math — enable optimizations that assume no Inf values. 🚫♾️
  • -enable-no-nans-fp-math — enable optimizations that assume no NAN values. 🚫👻
  • -enable-unsafe-fp-math — causes lli to enable optimizations that may decrease floating point precision. ⚠️ unsafe is right there in the name, bestie. 😭
  • -soft-float — causes lli to generate software floating point library calls instead of equivalent hardware instructions. doing it by hand, no hardware, no problem. 🧚

🔥 CODE GENERATION OPTIONS 🔥

the machinery. the engine room. she's literally built different. ⚙️✨

  • -code-model=model — choose the code model from:
    • default: Target default code model
    • tiny: Tiny code model
    • small: Small code model
    • kernel: Kernel code model
    • medium: Medium code model
    • large: Large code model

pick your size, goldilocks. 🐻

  • -disable-post-RA-scheduler — disable scheduling after register allocation. 🚫📅
  • -disable-spill-fusing — disable fusing of spill code into instructions. 🫗
  • -jit-enable-eh — exception handling should be enabled in the just-in-time compiler. 🚨
  • -join-liveintervals — coalesce copies (default=true). she's a joiner. 🫶
  • -nozero-initialized-in-bss — don't place zero-initialized symbols into the BSS section. 🚫0️⃣
  • -pre-RA-sched=scheduler — instruction schedulers available (before register allocation):
    • =default: Best scheduler for the target
    • =none: No scheduling: breadth first sequencing
    • =simple: Simple two pass scheduling: minimize critical path and maximize processor utilization
    • =simple-noitin: Simple two pass scheduling: Same as simple except using generic latency
    • =list-burr: Bottom-up register reduction list scheduling
    • =list-tdrr: Top-down register reduction list scheduling
    • =list-td: Top-down list scheduler -print-machineinstrs - Print generated machine code

so many options, so little time. 👑

  • -regalloc=allocator — register allocator to use (default=linearscan)
    • =bigblock: Big-block register allocator
    • =linearscan: linear scan register allocator =local - local register allocator
    • =simple: simple register allocator

💅

  • -relocation-model=model — choose relocation model from:
    • =default: Target default relocation model
    • =static: Non-relocatable code =pic - Fully relocatable, position independent code
    • =dynamic-no-pic: Relocatable external references, non-relocatable code

🦋

  • -spiller — spiller to use (default=local)
    • =simple: simple spiller
    • =local: local spiller

😭

  • -x86-asm-syntax=syntax — choose style of code to emit from X86 backend:
    • =att: Emit AT&T-style assembly
    • =intel: Emit Intel-style assembly

team AT&T vs team Intel, the eternal war. ⚔️

🚪 EXIT STATUS 🚪

if lli fails to load the program, she will exit with an exit code of 1. otherwise, she will return the exit code of the program she executes. so like, she's not taking credit for someone else's W or their L. periodt. 💯

👀 SEE ALSO 👀

  • llc(1) — go read her too, she's also iconic. 🫶

💜 AUTHOR 💜

maintained by the LLVM Team (<https://llvm.org/>). they're doing the lord's work fr fr. 👑

2003-2024, LLVM Project 🌈

and that's the whole page, bestie!! this was lli, section 1 of the manual, from the LLVM source, dated 2024-07-18, and the page number is 11. mwah. 💋 now go execute something. slay ✨💖🎀

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