Very hot stuff! It's like ISA-portable assembly, but with types! In particular it also it deals with calling conventions for us (since it is ISA-portable). TODO: isn't that exactly what C does? :-) LLVM IR vs C
Documentation: llvm.org/docs/LangRef.html
Example: llvm/hello.ll adapted from: llvm.org/docs/LangRef.html#module-structure but without double newline.
To execute it as mentioned at github.com/dfellis/llvm-hello-world we can either use their crazy assembly interpreter, tested on Ubuntu 22.10:
This seems to use
sudo apt install llvm-runtime
lli hello.ll
puts
from the C standard library.Or we can Lower it to assembly of the local machine:
which produces:
and then we can assemble link and run with gcc:
or with clang:
sudo apt install llvm
llc hello.ll
hello.s
gcc -o hello.out hello.s -no-pie
./hello.out
clang -o hello.out hello.s -no-pie
./hello.out
hello.s
uses the GNU GAS format, which clang is highly compatible with, so both should work in general.