LLI(1)

💖 LLI(1) — directly execute programs from LLVM bitcode 💖

okay bestie, gather round, because this is lli from section 1 of the manual, and it's genuinely one of the most main-character tools in the whole LLVM lineup. no cap. 🦋

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✨ NAME ✨

lli — directly execute programs from LLVM bitcode. yes that's the whole job description and she ate. 💅

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✨ SYNOPSIS ✨

lli [options] [filename] [program args]

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✨ DESCRIPTION ✨

so like, lli directly executes programs in LLVM bitcode format. you hand it a program that's in LLVM bitcode format and it runs it — either with a just-in-time compiler or with an interpreter. pick your fighter. 🔥

and listen, because this part matters: lli is not an emulator. it will not execute IR of different architectures, and it can only interpret (or JIT-compile) for the host architecture. it's giving "I only speak my own language, sorry bestie". 💀

the JIT compiler takes the same arguments as other tools, like llc, but heads up — they don't necessarily work for the interpreter. so don't come for the interpreter with JIT energy. 🙈

if filename is not specified, then lli reads the LLVM bitcode for the program from standard input. slay, it'll just vibe with whatever you pipe in. 🌸

the optional args specified on the command line are passed to the program as arguments. so your program gets them, like a little gift. 🎀

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✨ GENERAL OPTIONS ✨

• -fake-argv0=executable — Override the argv[0] value passed into the executing program. catfishing your own program, iconic. 👑
• -force-interpreter={false,true} — If set to true, use the interpreter even if a just-in-time compiler is available for this architecture. Defaults to false. (so by default she's JITting, but you can make her interpret. respect.)
• -help — Print a summary of command line options. the classic. always here for you. 🫶
• -load=pluginfilename — Causes lli to load the plugin (shared object) named pluginfilename and use it for optimization.
• -stats — Print statistics from the code-generation passes. This is only meaningful for the just-in-time compiler, at present. ngl, only relevant to the JIT girlies. ✨
• -time-passes — Record the amount of time needed for each code-generation pass and print it to standard error.
• -version — Print out the version of lli and exit without doing anything else. she said "here's my version, bye". 💅

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✨ TARGET OPTIONS ✨

• -mtriple=target triple — Override the target triple specified in the input bitcode file with the specified string.

⚠️ bestie, this may result in a crash if you pick an architecture which is not compatible with the current system. not me choosing violence against my own machine 😭

• -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, such as 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

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✨ FLOATING POINT OPTIONS ✨

the math girlies, this section is for you. 🧮✨

• -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, on purpose, as advertised. 💀
• -soft-float — Causes lli to generate software floating point library calls instead of equivalent hardware instructions.

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✨ CODE GENERATION OPTIONS ✨

okay this is the big one. so many knobs. she's high maintenance and we love that for her. 🎀

• -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

• -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). lowkey just doin her thing by default. 💜
• -nozero-initialized-in-bss — Don't place zero-initialized symbols into the BSS section.
• -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

• -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

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✨ EXIT STATUS ✨

if lli fails to load the program, it will exit with an exit code of 1. 😭

otherwise, it will return the exit code of the program it executes. so whatever your program says, lli says it back. fr fr. 🫶

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✨ SEE ALSO ✨

• llc(1) — go read that one next, bestie, it's her sister. 💖

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✨ AUTHOR ✨

Maintained by the LLVM Team (https://llvm.org/). the collective group chat that keeps this whole thing alive. 👑

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✨ COPYRIGHT ✨

2003-2024, LLVM Project

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and that's the whole page, bestie!! 🌈 this was LLI(1) from LLVM version 12, dated 2024-07-18 — so yeah, she's been serving since 2003 and she's still iconic. mwah. 💅💖🦋✨