LLI(1)

💅 LLI(1) — the lli page, aka the LLVM manual's main character ✨

okay so bestie, welcome to lli — yes that's the LLVM manual page, section 1, and she is literally the whole vibe. sit down, get a snack 🍓, and let's get into it.

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🎀 NAME 🎀

lli — runs programs straight out of LLVM bitcode, no extra steps, no cap 💅

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✨ SYNOPSIS ✨

lli [options] [filename] [program args]

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🦋 DESCRIPTION 🦋

so lli directly executes programs that are in LLVM bitcode format. like, you hand her a program in LLVM bitcode and she runs it — using a just-in-time compiler or an interpreter. she's flexible like that 🫶

and no, she is not an emulator. not even a little bit. she will not execute IR from different architectures, periodt. she can only interpret (or JIT-compile) for the host architecture — that's her lane and she stays in it 😌

the JIT compiler takes the same arguments as other tools, like llc, but heads up: those args don't necessarily work for the interpreter. lowkey different beasts, iykyk 💀

if filename isn't specified, then lli reads the LLVM bitcode for the program from standard input. stdin bestie, she'll take it 🌸

and the optional args you put on the command line? those get passed to the program as arguments. handing out lil gifts 🎁

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💜 GENERAL OPTIONS 💜

• -fake-argv0=executable — overrides the argv[0] value that gets passed into the executing program. lil identity swap moment 🙈
• -force-interpreter={false,true} — set it to true and she'll use the interpreter even if a just-in-time compiler is available for this architecture. defaults to false. yes she'll do it the hard way if you ask 💅
• -help — prints a summary of the command line options. the classic.
• -load=pluginfilename — makes lli load the plugin (that's a shared object) named pluginfilename and use it for optimization. plug her in ✨
• -stats — prints statistics from the code-generation passes. ngl this is only meaningful for the just-in-time compiler at present — she's honest about it 😭
• -time-passes — records how much time each code-generation pass needed and prints it to standard error. clocking the girlypops ⏱️
• -version — prints out the version of lli and exits without doing anything else. she said bye then left 👑

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🔥 TARGET OPTIONS 🔥

• -mtriple=target triple — overrides the target triple baked into the input bitcode file with the string you give her. ⚠️ careful bestie, this may result in a crash if you pick an architecture that isn't compatible with the current system. don't do her like that 💀
• -march=arch — specifies the architecture to generate assembly for, overriding the target encoded in the bitcode file. for a list of valid architectures, go see the output of llc -help. by default this is inferred from the target triple, or autodetected to the current architecture.
• -mcpu=cpuname — specifies 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,... — overrides or controls specific attributes of the target — stuff 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

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🧚 FLOATING POINT OPTIONS 🧚

• -disable-excess-fp-precision — disables optimizations that may increase floating point precision.
• -enable-no-infs-fp-math — enables optimizations that assume no Inf values.
• -enable-no-nans-fp-math — enables optimizations that assume no NAN values.
• -enable-unsafe-fp-math — causes lli to enable optimizations that may decrease floating point precision. unsafe, she said it, not me 🫣
• -soft-float — causes lli to generate software floating point library calls instead of the equivalent hardware instructions. doing it the soft way 💅

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⭐ CODE GENERATION OPTIONS ⭐

• -code-model=model — picks the code model from these:
  • 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 — disables scheduling after register allocation.
• -disable-spill-fusing — disables 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. nope, not there ✋
• -pre-RA-sched=scheduler — the 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 — the 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 — picks the 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 — the spiller to use (default=local):
  • =simple: simple spiller
  • =local: local spiller
• -x86-asm-syntax=syntax — picks the style of code emitted from the 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, she'll exit with an exit code of 1. that's the sad path 😭

otherwise? she returns the exit code of the program she executes. she's just the messenger, fr fr 🫶

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🌈 SEE ALSO 🌈

llc(1) — go say hi to her sister 💖

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🌸 AUTHOR 🌸

maintained by the LLVM Team (https://llvm.org/). iconic, they ate 👑

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💖 COPYRIGHT 💖

2003-2023, LLVM Project

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and that's the whole page bestie!! this was page version 17, dated 2023-12-01 — go forth and lli responsibly, mwah 🎀✨💅