Emerge Yul recompiler (#1)

Provide a modified (and incomplete) version of ZKSync zksolc that can compile the most basic contracts

crates/stdlib/build.rs

@@ -0,0 +1,31 @@
+use std::{env, fs, path::Path, process::Command};
+
+fn main() {
+    let lib = "stdlib.bc";
+    let out_dir = env::var_os("OUT_DIR").expect("env should have $OUT_DIR");
+    let bitcode_path = Path::new(&out_dir).join(lib);
+
+    let output = Command::new("llvm-as")
+        .args([
+            "-o",
+            bitcode_path.to_str().expect("$OUT_DIR should be UTF-8"),
+            "stdlib.ll",
+        ])
+        .output()
+        .expect("should be able to invoke llvm-as");
+
+    assert!(
+        output.status.success(),
+        "failed to assemble the stdlib: {:?}",
+        output
+    );
+
+    let bitcode = fs::read(bitcode_path).expect("bitcode should have been built");
+    let len = bitcode.len();
+    let src_path = Path::new(&out_dir).join("stdlib.rs");
+    let src = format!("pub static BITCODE: &[u8; {len}] = include_bytes!(\"{lib}\");");
+    fs::write(src_path, src).expect("should be able to write in $OUT_DIR");
+
+    println!("cargo:rerun-if-changed=stdlib.ll");
+    println!("cargo:rerun-if-changed=build.rs");
+}