LLVM unit tests: Write IR to file for failed test

ptx/src/test/spirv_run/mod.rs

@@ -1,10 +1,14 @@
 use crate::pass;
 use hip_runtime_sys::hipError_t;
+use std::env;
 use std::error;
 use std::ffi::{CStr, CString};
-use std::fmt;
+use std::fmt::{self, Debug, Display, Formatter};
-use std::fmt::{Debug, Display, Formatter};
+use std::fs::{create_dir_all, File};
+use std::io::Write;
+use std::panic::{catch_unwind, resume_unwind};
 use std::mem;
+use std::path::Path;
 use std::{ptr, str};
 use pretty_assertions;
 
@@ -33,10 +37,9 @@ macro_rules! test_ptx {
         paste::item! {
             #[test]
             fn [<$fn_name _llvm>]() -> Result<(), Box<dyn std::error::Error>> {
-                let fn_name = stringify!($fn_name);
                 let ptx = include_str!(concat!(stringify!($fn_name), ".ptx"));
                 let ll = include_str!(concat!("../ll/", stringify!($fn_name), ".ll")).trim();
-                test_llvm_assert(ptx, &ll)
+                test_llvm_assert(stringify!($fn_name), ptx, &ll)
             }
         }
     };
@@ -237,13 +240,28 @@ fn test_hip_assert<
 fn test_llvm_assert<
     'a,
 >(
+    name: &str,
     ptx_text: &'a str,
     expected_ll: &str
 ) -> Result<(), Box<dyn error::Error + 'a>> {
     let ast = ptx_parser::parse_module_checked(ptx_text).unwrap();
     let llvm_ir = pass::to_llvm_module(ast).unwrap();
     let actual_ll = llvm_ir.llvm_ir.print_as_asm();
-    pretty_assertions::assert_eq!(actual_ll, expected_ll);
+    let result = catch_unwind(||
+        pretty_assertions::assert_eq!(actual_ll, expected_ll));
+    if let Err(cause) = result {
+        // Write actual generated LLVM IR to directory specified by environment variable
+        // TEST_PTX_LLVM_FAIL_DIR if test fails
+        let output_dir = env::var("TEST_PTX_LLVM_FAIL_DIR");
+        if let Ok(output_dir) = output_dir {
+            let output_dir = Path::new(&output_dir);
+            create_dir_all(&output_dir).unwrap();
+            let output_file = output_dir.join(format!("{}.ll", name));
+            let mut output_file = File::create(output_file).unwrap();
+            output_file.write_all(actual_ll.as_bytes()).unwrap();
+        }
+        resume_unwind(cause);
+    }
     Ok(())
 }