Add documentation

Readme.md

@@ -71,6 +71,14 @@ or
 $ $cg_clif_dir/build/bin/cg_clif -Cllvm-args=mode=jit -Cprefer-dynamic my_crate.rs
 ```
 
+There is also an experimental lazy jit mode. In this mode functions are only compiled once they are
+first called. It currently does not work with multi-threaded programs. When a not yet compiled
+function is called from another thread than the main thread, you will get an ICE.
+
+```bash
+$ $cg_clif_dir/build/cargo.sh lazy-jit
+```
+
 ### Shell
 
 These are a few functions that allow you to easily run rust code from the shell using cg_clif as jit.

scripts/cargo.sh

@@ -11,6 +11,8 @@ shift || true
 
 if [[ "$cmd" = "jit" ]]; then
 cargo "+${TOOLCHAIN}" rustc "$@" -- -Cllvm-args=mode=jit -Cprefer-dynamic
+elif [[ "$cmd" = "lazy-jit" ]]; then
+cargo "+${TOOLCHAIN}" rustc "$@" -- -Cllvm-args=mode=jit-lazy -Cprefer-dynamic
 else
 cargo "+${TOOLCHAIN}" "$cmd" "$@"
 fi