From 6f4585e7d84c587f2e4531bbd3e2a2367985f23e Mon Sep 17 00:00:00 2001
From: Folkert <folkert@folkertdev.nl>
Date: Wed, 18 Nov 2020 19:24:49 +0100
Subject: [PATCH] add subprogram debug info

---
 compiler/gen/src/llvm/build.rs | 74 ++++++++++++++++++++++++++--------
 1 file changed, 57 insertions(+), 17 deletions(-)

diff --git a/compiler/gen/src/llvm/build.rs b/compiler/gen/src/llvm/build.rs
index e658a40b3b..b136b44c8b 100644
--- a/compiler/gen/src/llvm/build.rs
+++ b/compiler/gen/src/llvm/build.rs
@@ -17,7 +17,7 @@ use bumpalo::Bump;
 use inkwell::basic_block::BasicBlock;
 use inkwell::builder::Builder;
 use inkwell::context::Context;
-use inkwell::debug_info::{DICompileUnit, DISubprogram, DebugInfoBuilder};
+use inkwell::debug_info::{AsDIScope, DICompileUnit, DISubprogram, DebugInfoBuilder};
 use inkwell::memory_buffer::MemoryBuffer;
 use inkwell::module::{Linkage, Module};
 use inkwell::passes::{PassManager, PassManagerBuilder};
@@ -201,7 +201,6 @@ impl<'a, 'ctx, 'env> Env<'a, 'ctx, 'env> {
     }
 
     pub fn new_subprogram(&self, function_name: &str) -> DISubprogram<'ctx> {
-        use inkwell::debug_info::AsDIScope;
         use inkwell::debug_info::DIFlagsConstants;
 
         let dibuilder = self.dibuilder;
@@ -1042,21 +1041,20 @@ pub fn allocate_with_refcount<'a, 'ctx, 'env>(
     let ctx = env.context;
 
     let value_type = basic_type_from_layout(env.arena, ctx, layout, env.ptr_bytes);
-    let value_bytes = layout.stack_size(env.ptr_bytes) as u64;
+    let value_bytes = layout.stack_size(env.ptr_bytes);
 
     let len_type = env.ptr_int();
-    // bytes per element
-    let bytes_len = len_type.const_int(value_bytes, false);
 
     let extra_bytes = layout.alignment_bytes(env.ptr_bytes);
-    let extra_bytes_intvalue = len_type.const_int(extra_bytes as u64, false);
 
     let ptr = {
-        let len = bytes_len;
-        let len = builder.build_int_add(len, extra_bytes_intvalue, "add_alignment_space");
+        let len = value_bytes as u64 + extra_bytes as u64;
+
+        // bytes per element
+        let bytes_len = len_type.const_int(len, false);
 
         env.builder
-            .build_array_malloc(ctx.i8_type(), len, "create_ptr")
+            .build_array_malloc(ctx.i8_type(), bytes_len, "create_ptr")
             .unwrap()
 
         // TODO check if malloc returned null; if so, runtime error for OOM!
@@ -1065,15 +1063,33 @@ pub fn allocate_with_refcount<'a, 'ctx, 'env>(
     // We must return a pointer to the first element:
     let data_ptr = {
         let int_type = ptr_int(ctx, env.ptr_bytes);
-        let ptr_as_int = builder.build_ptr_to_int(ptr, int_type, "calculate_data_ptr_pti");
-        let incremented = builder.build_int_add(
-            ptr_as_int,
-            extra_bytes_intvalue,
-            "calculate_data_ptr_increment",
-        );
+        let as_usize_ptr = cast_basic_basic(
+            env.builder,
+            ptr.into(),
+            int_type.ptr_type(AddressSpace::Generic).into(),
+        )
+        .into_pointer_value();
+
+        let index = match extra_bytes {
+            n if n == env.ptr_bytes => 1,
+            n if n == 2 * env.ptr_bytes => 2,
+            _ => unreachable!("invalid extra_bytes"),
+        };
+
+        let index_intvalue = int_type.const_int(index, false);
 
         let ptr_type = get_ptr_type(&value_type, AddressSpace::Generic);
-        builder.build_int_to_ptr(incremented, ptr_type, "calculate_data_ptr")
+
+        unsafe {
+            cast_basic_basic(
+                env.builder,
+                env.builder
+                    .build_in_bounds_gep(as_usize_ptr, &[index_intvalue], "get_data_ptr")
+                    .into(),
+                ptr_type.into(),
+            )
+            .into_pointer_value()
+        }
     };
 
     let refcount_ptr = match extra_bytes {
@@ -1666,7 +1682,10 @@ fn expose_function_to_host<'a, 'ctx, 'env>(
 ) {
     let c_function_name: String = format!("{}_exposed", roc_function.get_name().to_str().unwrap());
 
-    expose_function_to_host_help(env, roc_function, &c_function_name);
+    let result = expose_function_to_host_help(env, roc_function, &c_function_name);
+
+    let subprogram = env.new_subprogram(&c_function_name);
+    result.set_subprogram(subprogram);
 }
 
 fn expose_function_to_host_help<'a, 'ctx, 'env>(
@@ -2011,6 +2030,9 @@ pub fn build_proc_header<'a, 'ctx, 'env>(
 
     fn_val.set_call_conventions(FAST_CALL_CONV);
 
+    let subprogram = env.new_subprogram(&fn_name);
+    fn_val.set_subprogram(subprogram);
+
     if env.exposed_to_host.contains(&symbol) {
         expose_function_to_host(env, fn_val);
     }
@@ -2150,6 +2172,24 @@ pub fn build_proc<'a, 'ctx, 'env>(
 
     builder.position_at_end(entry);
 
+    let func_scope = fn_val.get_subprogram().unwrap();
+    let lexical_block = env.dibuilder.create_lexical_block(
+        /* scope */ func_scope.as_debug_info_scope(),
+        /* file */ env.compile_unit.get_file(),
+        /* line_no */ 0,
+        /* column_no */ 0,
+    );
+
+    let loc = env.dibuilder.create_debug_location(
+        context,
+        /* line */ 0,
+        /* column */ 0,
+        /* current_scope */ lexical_block.as_debug_info_scope(),
+        /* inlined_at */ None,
+    );
+
+    builder.set_current_debug_location(&context, loc);
+
     // Add args to scope
     for (arg_val, (layout, arg_symbol)) in fn_val.get_param_iter().zip(args) {
         set_name(arg_val, arg_symbol.ident_string(&env.interns));