zixing@zixing-ubuntu /tmp> llc-15 --version
Ubuntu LLVM version 15.0.7
  Optimized build.
  Default target: x86_64-pc-linux-gnu
  Host CPU: skylake

  Registered Targets:
    aarch64    - AArch64 (little endian)
    aarch64_32 - AArch64 (little endian ILP32)
    aarch64_be - AArch64 (big endian)
    amdgcn     - AMD GCN GPUs
    arm        - ARM
    arm64      - ARM64 (little endian)
    arm64_32   - ARM64 (little endian ILP32)
    armeb      - ARM (big endian)
    avr        - Atmel AVR Microcontroller
    bpf        - BPF (host endian)
    bpfeb      - BPF (big endian)
    bpfel      - BPF (little endian)
    hexagon    - Hexagon
    lanai      - Lanai
    m68k       - Motorola 68000 family
    mips       - MIPS (32-bit big endian)
    mips64     - MIPS (64-bit big endian)
    mips64el   - MIPS (64-bit little endian)
    mipsel     - MIPS (32-bit little endian)
    msp430     - MSP430 [experimental]
    nvptx      - NVIDIA PTX 32-bit
    nvptx64    - NVIDIA PTX 64-bit
    ppc32      - PowerPC 32
    ppc32le    - PowerPC 32 LE
    ppc64      - PowerPC 64
    ppc64le    - PowerPC 64 LE
    r600       - AMD GPUs HD2XXX-HD6XXX
    riscv32    - 32-bit RISC-V
    riscv64    - 64-bit RISC-V
    sparc      - Sparc
    sparcel    - Sparc LE
    sparcv9    - Sparc V9
    systemz    - SystemZ
    thumb      - Thumb
    thumbeb    - Thumb (big endian)
    ve         - VE
    wasm32     - WebAssembly 32-bit
    wasm64     - WebAssembly 64-bit
    x86        - 32-bit X86: Pentium-Pro and above
    x86-64     - 64-bit X86: EM64T and AMD64
    xcore      - XCore
zixing@zixing-ubuntu /tmp> llc-15 -O0 reduced.ll.txt -o t.S
zixing@zixing-ubuntu /tmp> head -n10 t.S
        .text
        .abiversion 2
        .file   "reduced.ll.txt"
        .file   1 "/home/jistone/rust" "library/std/src/io/stdio.rs"
        .file   2 "/home/jistone/rust" "library/std/src/thread/local.rs"
        .file   3 "/home/jistone/rust" "library/std/src/sys/unix/fs.rs"
        .file   4 "/home/jistone/rust" "library/std/src/sys/unix/process/process_unix.rs"
        .globl  _ZN55_$LT$std..io..stdio..Stdin$u20$as$u20$std..io..Read$GT$11read_to_end17haba70a09681d41d3E # -- Begin function _ZN55_$LT$std..io..stdio..Stdin$u20$as$u20$std..io..Read$GT$11read_to_end17haba70a09681d41d3E
        .p2align        4
        .type   _ZN55_$LT$std..io..stdio..Stdin$u20$as$u20$std..io..Read$GT$11read_to_end17haba70a09681d41d3E,@function
zixing@zixing-ubuntu /tmp>