undefined reference to `main'

[Xawx]

Hi!

I generated sum.bc file with code from Readme

then I took LLVM 9 from https://apt.llvm.org/ and installed it on Debian 10 (Hyper-V)

# LLVM
apt-get install libllvm-9-ocaml-dev libllvm9 llvm-9 llvm-9-dev llvm-9-doc llvm-9-examples llvm-9-runtime
# Clang and co
apt-get install clang-9 clang-tools-9 clang-9-doc libclang-common-9-dev libclang-9-dev libclang1-9 clang-format-9 python-clang-9 clangd-9
# libfuzzer
apt-get install libfuzzer-9-dev
# lldb
apt-get install lldb-9
# lld (linker)
apt-get install lld-9
# libc++
apt-get install libc++-9-dev libc++abi-9-dev
# OpenMP
apt-get install libomp-9-dev

Then I tried changing that generated sum.bc to executable, but it says that undefined reference to 'main'

user@debian:~/Desktop/test$ llc -filetype=obj sum.bc
user@debian:~/Desktop/test$ ls
sum.bc  sum.o
user@debian:~/Desktop/test$ gcc sum.o
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status

what may be causing that?