add --debug mode that annotates LLVM IR with debug info

BUILDING_FROM_SOURCE.md

@@ -16,6 +16,8 @@ To run the test suite (via `cargo test`), you additionally need to install:
 * [`valgrind`](https://www.valgrind.org/) (needs special treatment to [install on macOS](https://stackoverflow.com/a/61359781)
 Alternatively, you can use `cargo test --no-fail-fast` or `cargo test -p specific_tests` to skip over the valgrind failures & tests.
 
+For debugging LLVM IR, we use [DebugIR](https://github.com/vaivaswatha/debugir). This dependency is only required to build with the `--debug` flag, and for normal developtment you should be fine without it. 
+
 ### libunwind & libc++-dev
 
 MacOS systems should already have `libunwind`, but other systems will need to install it (On Ubuntu, this can be donw with `sudo apt-get install libunwind-dev`).

cli/src/build.rs

@@ -24,6 +24,7 @@ pub fn build_file(
     src_dir: PathBuf,
     roc_file_path: PathBuf,
     opt_level: OptLevel,
+    emit_debug_info: bool,
     link_type: LinkType,
 ) -> Result<PathBuf, LoadingProblem> {
     let compilation_start = SystemTime::now();
@@ -95,6 +96,7 @@ pub fn build_file(
         Triple::host(),
         &app_o_file,
         opt_level,
+        emit_debug_info,
     );
 
     println!("\nSuccess! 🎉\n\n\t➡ {}\n", app_o_file.display());

cli/src/lib.rs

@@ -14,6 +14,7 @@ use target_lexicon::Triple;
 pub mod build;
 pub mod repl;
 
+pub static FLAG_DEBUG: &str = "debug";
 pub static FLAG_OPTIMIZE: &str = "optimize";
 pub static FLAG_ROC_FILE: &str = "ROC_FILE";
 pub static DIRECTORY_OR_FILES: &str = "DIRECTORY_OR_FILES";
@@ -34,6 +35,12 @@ pub fn build_app<'a>() -> App<'a> {
                     .help("Optimize the compiled program to run faster. (Optimization takes time to complete.)")
                     .required(false),
             )
+            .arg(
+                Arg::with_name(FLAG_DEBUG)
+                    .long(FLAG_DEBUG)
+                    .help("Store LLVM debug information in the generated program")
+                    .required(false),
+            )
         )
         .subcommand(App::new("run")
             .about("Build and run a program")
@@ -48,6 +55,12 @@ pub fn build_app<'a>() -> App<'a> {
                     .help("Optimize the compiled program to run faster. (Optimization takes time to complete.)")
                     .required(false),
             )
+            .arg(
+                Arg::with_name(FLAG_DEBUG)
+                    .long(FLAG_DEBUG)
+                    .help("Store LLVM debug information in the generated program")
+                    .required(false),
+            )
         )
         .subcommand(App::new("repl")
             .about("Launch the interactive Read Eval Print Loop (REPL)")
@@ -70,6 +83,8 @@ pub fn build(target: &Triple, matches: &ArgMatches, run_after_build: bool) -> io
     } else {
         OptLevel::Normal
     };
+    let emit_debug_info = matches.is_present(FLAG_DEBUG);
+
     let path = Path::new(filename).canonicalize().unwrap();
     let src_dir = path.parent().unwrap().canonicalize().unwrap();
 
@@ -92,7 +107,14 @@ pub fn build(target: &Triple, matches: &ArgMatches, run_after_build: bool) -> io
         }
     });
 
-    let binary_path = build::build_file(target, src_dir, path, opt_level, LinkType::Executable)
+    let binary_path = build::build_file(
+        target,
+        src_dir,
+        path,
+        opt_level,
+        emit_debug_info,
+        LinkType::Executable,
+    )
     .expect("TODO gracefully handle build_file failing");
 
     if run_after_build {

compiler/build/src/program.rs

@@ -20,6 +20,7 @@ pub fn gen_from_mono_module(
     target: Triple,
     app_o_file: &Path,
     opt_level: OptLevel,
+    emit_debug_info: bool,
 ) {
     use roc_reporting::report::{
         can_problem, mono_problem, type_problem, RocDocAllocator, DEFAULT_PALETTE,
@@ -161,7 +162,9 @@ pub fn gen_from_mono_module(
 
     // annotate the LLVM IR output with debug info
     // so errors are reported with the line number of the LLVM source
-    if true {
+    if emit_debug_info {
+        module.strip_debug_info();
+
         let mut app_ll_file = std::path::PathBuf::from(app_o_file);
         app_ll_file.set_extension("ll");
 
@@ -217,20 +220,19 @@ pub fn gen_from_mono_module(
             ])
             .output()
             .unwrap();
-
+    } else {
-        return;
-    }
-
         // Emit the .o file
 
         let reloc = RelocMode::Default;
         let model = CodeModel::Default;
-    let target_machine = target::target_machine(&target, opt_level.into(), reloc, model).unwrap();
+        let target_machine =
+            target::target_machine(&target, opt_level.into(), reloc, model).unwrap();
 
         target_machine
             .write_to_file(&env.module, FileType::Object, &app_o_file)
             .expect("Writing .o file failed");
     }
+}
 
 pub struct FunctionIterator<'ctx> {
     next: Option<FunctionValue<'ctx>>,

examples/effect/Main.roc

@@ -1,11 +1,18 @@
-app "effect-example" imports [ Effect, RBTree ] provides [ main ] to "./platform"
+app "effect-example" imports [ Effect ] provides [ main ] to "./platform"
+
 
 main : Effect.Effect {} as Fx
 main =
-    if RBTree.isEmpty (RBTree.insert 1 2 Empty) then
+    when if 1 == 1 then True 3 else False 3.14 is
-        Effect.putLine "Yay"
+        True 3 -> Effect.putLine "Yay"
-            |> Effect.after (\{} -> Effect.getLine)
+        _ -> Effect.putLine "Yay"
-            |> Effect.after (\line -> Effect.putLine line)
-    else
-        Effect.putLine "Nay"
 
+# main : Effect.Effect {} as Fx
+# main =
+#     if RBTree.isEmpty (RBTree.insert 1 2 Empty) then
+#         Effect.putLine "Yay"
+#             |> Effect.after (\{} -> Effect.getLine)
+#             |> Effect.after (\line -> Effect.putLine line)
+#     else
+#         Effect.putLine "Nay"
+# 

examples/effect/platform/src/lib.rs

@@ -95,7 +95,12 @@ pub fn rust_main() -> isize {
 
                 let closure_data_ptr = buffer.offset(16);
 
-                call_the_closure(function_pointer as *const u8, closure_data_ptr as *const u8)
+                let result =
+                    call_the_closure(function_pointer as *const u8, closure_data_ptr as *const u8);
+
+                std::alloc::dealloc(buffer, layout);
+
+                result
             }
             Err(msg) => {
                 std::alloc::dealloc(buffer, layout);