add enzyme submodule

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "Enzyme"]
+	path = Enzyme
+	url = https://github.com/EnzymeAD/Enzyme.git

build.rs

@@ -14,7 +14,6 @@ fn main() {
     for (key, value) in env::vars() {
         println!("{}: {}", key, value);
     }
-
     // get env vars matching DEP_LLVM_*_LIBDIR regex    
     let llvm_dirs: Vec<_> = env::vars().filter(|(k, _)| k.starts_with("DEP_LLVM_") && k.ends_with("_LIBDIR")).collect();
     // take first one
@@ -25,4 +24,5 @@ fn main() {
     // compile enzyme
     let libdir= compile_enzyme(llvm_dir);
     println!("cargo:rustc-link-search=native={}", libdir);
+    println!("cargo:rerun-if-changed=build.rs");
 }

src/execution/compiler.rs

@@ -78,16 +78,28 @@ impl Compiler {
     fn find_clang() -> Result<&'static str> {
         find_executable(&Compiler::CLANG_VARIENTS)
     }
+    /// search for the enzyme library in the environment variables
     fn find_enzyme_lib() -> Result<String> {
-        // print all the environment variables
-        for (key, value) in env::vars() {
-            println!("{}: {}", key, value);
-        }
-        match env::var("DEP_ENZYME_SYS_LIBDIR") {
-            Ok(lib) => Ok(lib),
-            Err(_) => Err(anyhow!("DEP_ENZYME_SYS_LIBDIR environment variable not set")),
-
+        let env_vars = ["LD_LIBRARY_PATH", "DYLD_LIBRARY_PATH", "PATH"];
+        for var in env_vars.iter() {
+            if let Ok(val) = env::var(var) {
+                for path in val.split(":") {
+                    // check that LLVMEnzype*.so exists in this directory
+                    if let Ok(entries) = std::fs::read_dir(path) {
+                        for entry in entries {
+                            if let Ok(entry) = entry {
+                                if let Some(filename) = entry.file_name().to_str() {
+                                    if filename.starts_with("LLVMEnzyme") && filename.ends_with(".so") {
+                                        return Ok(entry.path().to_str().unwrap().to_owned());
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
         }
+        Err(anyhow!("LLVMEnzyme*.so not found in any of: {:?}", env_vars))
     }
     pub fn from_discrete_str(code: &str) -> Result<Self> {
         let uid = Id::<u32>::new();

src/utils.rs

@@ -1,20 +1,19 @@
 use std::env;
 use std::path::Path;
-use std::process::Command;
 
 use anyhow::Result;
 use anyhow::anyhow;
 
 fn is_executable_on_path(executable_name: &str) -> bool {
-    let output = Command::new("which")
-        .arg(executable_name)
-        .output()
-        .expect("failed to execute which command");
-
-    output.status.success()
+    for path in env::var("PATH").unwrap().split(':') {
+        let path = Path::new(path).join(executable_name);
+        if path.exists() {
+            return true;
+        }
+    }
+    false
 }
 
-
 pub fn find_executable<'a>(varients: &[&'a str]) -> Result<&'a str> {
     let mut command = None;
     for varient in varients {
@@ -29,7 +28,6 @@ pub fn find_executable<'a>(varients: &[&'a str]) -> Result<&'a str> {
     }
 }
 
-
 pub fn find_runtime_path(libraries: &[&str] ) -> Result<String> {
     // search in EMSDK lib dir and LIBRARY_PATH env variable
     let emsdk_lib = env::var("EMSDK").unwrap_or("".to_owned()) + "/upstream/emscripten/cache/sysroot/lib";