experimental: support for debug info (#118)

Signed-off-by: wpt967 <matt.aw@parity.io>
Signed-off-by: xermicus <cyrill@parity.io>

crates/llvm-context/src/polkavm/context/debug_info.rs

@@ -1,7 +1,43 @@
 //! The LLVM debug information.
 
+use std::cell::RefCell;
+
 use inkwell::debug_info::AsDIScope;
-use num::Zero;
+use inkwell::debug_info::DIScope;
+
+/// Debug info scope stack
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ScopeStack<'ctx> {
+    stack: Vec<DIScope<'ctx>>,
+}
+
+// Abstract the type of the DIScope stack.
+impl<'ctx> ScopeStack<'ctx> {
+    pub fn from(item: DIScope<'ctx>) -> Self {
+        Self { stack: vec![item] }
+    }
+
+    /// Return the top of the scope stack, or None if the stack is empty.
+    pub fn top(&self) -> Option<DIScope<'ctx>> {
+        self.stack.last().copied()
+    }
+
+    /// Push a scope onto the stack.
+    pub fn push(&mut self, scope: DIScope<'ctx>) {
+        self.stack.push(scope)
+    }
+
+    /// Pop the scope at the top of the stack and return it.
+    /// Return None if the stack is empty.
+    pub fn pop(&mut self) -> Option<DIScope<'ctx>> {
+        self.stack.pop()
+    }
+
+    /// Return the number of scopes on the stack.
+    pub fn len(&self) -> usize {
+        self.stack.len()
+    }
+}
 
 /// The LLVM debug information.
 pub struct DebugInfo<'ctx> {
@@ -9,6 +45,8 @@ pub struct DebugInfo<'ctx> {
     compile_unit: inkwell::debug_info::DICompileUnit<'ctx>,
     /// The debug info builder.
     builder: inkwell::debug_info::DebugInfoBuilder<'ctx>,
+    /// Enclosing debug info scopes.
+    scope_stack: RefCell<ScopeStack<'ctx>>,
 }
 
 impl<'ctx> DebugInfo<'ctx> {
@@ -35,19 +73,43 @@ impl<'ctx> DebugInfo<'ctx> {
         Self {
             compile_unit,
             builder,
+            scope_stack: RefCell::new(ScopeStack::from(compile_unit.as_debug_info_scope())),
         }
     }
 
+    /// Prepare an LLVM-IR module for debug-info generation
+    pub fn initialize_module(
+        &self,
+        llvm: &'ctx inkwell::context::Context,
+        module: &inkwell::module::Module<'ctx>,
+    ) {
+        let debug_metadata_value = llvm
+            .i32_type()
+            .const_int(inkwell::debug_info::debug_metadata_version() as u64, false);
+        module.add_basic_value_flag(
+            "Debug Info Version",
+            inkwell::module::FlagBehavior::Warning,
+            debug_metadata_value,
+        );
+        self.push_scope(self.compilation_unit().get_file().as_debug_info_scope());
+    }
+
+    /// Finalize debug-info for an LLVM-IR module.
+    pub fn finalize_module(&self) {
+        self.builder().finalize()
+    }
+
     /// Creates a function info.
     pub fn create_function(
         &self,
         name: &str,
     ) -> anyhow::Result<inkwell::debug_info::DISubprogram<'ctx>> {
+        let flags = inkwell::debug_info::DIFlagsConstants::ZERO;
         let subroutine_type = self.builder.create_subroutine_type(
             self.compile_unit.get_file(),
-            Some(self.create_type(revive_common::BIT_LENGTH_FIELD)?),
+            Some(self.create_word_type(Some(flags))?.as_type()),
             &[],
-            inkwell::debug_info::DIFlags::zero(),
+            flags,
         );
 
         let function = self.builder.create_function(
@@ -60,7 +122,7 @@ impl<'ctx> DebugInfo<'ctx> {
             true,
             false,
             1,
-            inkwell::debug_info::DIFlags::zero(),
+            flags,
             false,
         );
 
@@ -74,24 +136,55 @@ impl<'ctx> DebugInfo<'ctx> {
         Ok(function)
     }
 
-    /// Creates a primitive type info.
-    pub fn create_type(
+    /// Creates primitive integer type debug-info.
+    pub fn create_primitive_type(
         &self,
         bit_length: usize,
-    ) -> anyhow::Result<inkwell::debug_info::DIType<'ctx>> {
+        flags: Option<inkwell::debug_info::DIFlags>,
+    ) -> anyhow::Result<inkwell::debug_info::DIBasicType<'ctx>> {
+        let di_flags = flags.unwrap_or(inkwell::debug_info::DIFlagsConstants::ZERO);
+        let di_encoding: u32 = 0;
+        let type_name = String::from("U") + bit_length.to_string().as_str();
         self.builder
-            .create_basic_type(
-                "U256",
-                bit_length as u64,
-                0,
-                inkwell::debug_info::DIFlags::zero(),
-            )
-            .map(|basic_type| basic_type.as_type())
+            .create_basic_type(type_name.as_str(), bit_length as u64, di_encoding, di_flags)
             .map_err(|error| anyhow::anyhow!("Debug info error: {}", error))
     }
 
-    /// Finalizes the builder.
-    pub fn finalize(&self) {
-        self.builder.finalize();
+    /// Returns the debug-info model of word-sized integer types.
+    pub fn create_word_type(
+        &self,
+        flags: Option<inkwell::debug_info::DIFlags>,
+    ) -> anyhow::Result<inkwell::debug_info::DIBasicType<'ctx>> {
+        self.create_primitive_type(revive_common::BIT_LENGTH_WORD, flags)
+    }
+
+    /// Return the DIBuilder.
+    pub fn builder(&self) -> &inkwell::debug_info::DebugInfoBuilder<'ctx> {
+        &self.builder
+    }
+
+    /// Return the compilation unit. {
+    pub fn compilation_unit(&self) -> &inkwell::debug_info::DICompileUnit<'ctx> {
+        &self.compile_unit
+    }
+
+    /// Push a debug-info scope onto the stack.
+    pub fn push_scope(&self, scope: DIScope<'ctx>) {
+        self.scope_stack.borrow_mut().push(scope)
+    }
+
+    /// Pop the top of the debug-info scope stack and return it.
+    pub fn pop_scope(&self) -> Option<DIScope<'ctx>> {
+        self.scope_stack.borrow_mut().pop()
+    }
+
+    /// Return the top of the debug-info scope stack.
+    pub fn top_scope(&self) -> Option<DIScope<'ctx>> {
+        self.scope_stack.borrow().top()
+    }
+
+    /// Return the number of debug-info scopes on the scope stack.
+    pub fn num_scopes(&self) -> usize {
+        self.scope_stack.borrow().len()
     }
 }