From 53509fe412932959da805130daaa8fc6723372e8 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 28 Mar 2024 11:09:05 +0000
Subject: [PATCH] [STASH] Debuginfo for stackslots

---
 src/debuginfo/mod.rs               | 40 ++++++++++++++++++++++++++++
 src/debuginfo/placeholder_types.rs | 42 ++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 src/debuginfo/placeholder_types.rs

diff --git a/src/debuginfo/mod.rs b/src/debuginfo/mod.rs
index f3a8623e2..52cde8b78 100644
--- a/src/debuginfo/mod.rs
+++ b/src/debuginfo/mod.rs
@@ -3,6 +3,7 @@
 mod emit;
 mod line_info;
 mod object;
+mod placeholder_types;
 mod types;
 mod unwind;
 
@@ -23,6 +24,7 @@ use rustc_span::{FileNameDisplayPreference, SourceFileHash, StableSourceFileId};
 use rustc_target::callconv::FnAbi;
 
 pub(crate) use self::emit::{DebugReloc, DebugRelocName};
+use self::placeholder_types::PlaceholderTypeDebugContext;
 pub(crate) use self::types::TypeDebugContext;
 pub(crate) use self::unwind::UnwindContext;
 use crate::debuginfo::emit::{address_for_data, address_for_func};
@@ -41,6 +43,7 @@ pub(crate) struct DebugContext {
     stack_pointer_register: Register,
     namespace_map: DefIdMap<UnitEntryId>,
     array_size_type: UnitEntryId,
+    placeholder_types: PlaceholderTypeDebugContext,
 
     filename_display_preference: FileNameDisplayPreference,
 }
@@ -145,6 +148,8 @@ impl DebugContext {
             AttributeValue::Udata(isa.frontend_config().pointer_bytes().into()),
         );
 
+        let placeholder_types = PlaceholderTypeDebugContext::new(&mut dwarf);
+
         DebugContext {
             endian,
             dwarf,
@@ -153,6 +158,7 @@ impl DebugContext {
             stack_pointer_register,
             namespace_map: DefIdMap::default(),
             array_size_type,
+            placeholder_types,
             filename_display_preference,
         }
     }
@@ -317,6 +323,22 @@ impl DebugContext {
 }
 
 impl FunctionDebugContext {
+    fn define_raw_local(
+        &mut self,
+        debug_context: &mut DebugContext,
+        scope: UnitEntryId,
+        name: String,
+        dw_ty: UnitEntryId,
+    ) -> UnitEntryId {
+        let var_id = debug_context.dwarf.unit.add(scope, gimli::DW_TAG_variable);
+        let var_entry = debug_context.dwarf.unit.get_mut(var_id);
+
+        var_entry.set(gimli::DW_AT_name, AttributeValue::String(name.into_bytes()));
+        var_entry.set(gimli::DW_AT_type, AttributeValue::UnitRef(dw_ty));
+
+        var_id
+    }
+
     pub(crate) fn finalize(
         mut self,
         debug_context: &mut DebugContext,
@@ -335,5 +357,23 @@ impl FunctionDebugContext {
         func_entry.set(gimli::DW_AT_low_pc, AttributeValue::Address(address_for_func(func_id)));
         // Using Udata for DW_AT_high_pc requires at least DWARF4
         func_entry.set(gimli::DW_AT_high_pc, AttributeValue::Udata(u64::from(end)));
+
+        for (stack_slot, &offset) in &context.compiled_code().unwrap().sized_stackslot_offsets {
+            let size = context.func.sized_stack_slots[stack_slot].size;
+
+            let array_type_id = debug_context.placeholder_type(size.into());
+
+            let var_id = self.define_raw_local(
+                debug_context,
+                self.entry_id,
+                stack_slot.to_string(),
+                array_type_id,
+            );
+            let var_entry = debug_context.dwarf.unit.get_mut(var_id);
+
+            let mut expr = Expression::new();
+            expr.op_fbreg(offset.into());
+            var_entry.set(gimli::DW_AT_location, AttributeValue::Exprloc(expr));
+        }
     }
 }
diff --git a/src/debuginfo/placeholder_types.rs b/src/debuginfo/placeholder_types.rs
new file mode 100644
index 000000000..7bc2f741e
--- /dev/null
+++ b/src/debuginfo/placeholder_types.rs
@@ -0,0 +1,42 @@
+use gimli::write::{AttributeValue, DwarfUnit, UnitEntryId};
+use rustc_data_structures::fx::FxHashMap;
+
+use super::DebugContext;
+
+pub(crate) struct PlaceholderTypeDebugContext {
+    // Placeholders
+    u8_type: UnitEntryId,
+    placeholder_types: FxHashMap<u64, UnitEntryId>,
+}
+
+impl PlaceholderTypeDebugContext {
+    pub(super) fn new(dwarf: &mut DwarfUnit) -> Self {
+        let u8_type = dwarf.unit.add(dwarf.unit.root(), gimli::DW_TAG_base_type);
+        let u8_type_entry = dwarf.unit.get_mut(u8_type);
+        u8_type_entry.set(gimli::DW_AT_name, AttributeValue::StringRef(dwarf.strings.add("u8")));
+        u8_type_entry.set(gimli::DW_AT_encoding, AttributeValue::Encoding(gimli::DW_ATE_unsigned));
+        u8_type_entry.set(gimli::DW_AT_byte_size, AttributeValue::Udata(1));
+
+        PlaceholderTypeDebugContext { u8_type, placeholder_types: FxHashMap::default() }
+    }
+}
+
+impl DebugContext {
+    pub(crate) fn placeholder_type(&mut self, size: u64) -> UnitEntryId {
+        *self.placeholder_types.placeholder_types.entry(size).or_insert_with(|| {
+            let array_type_id =
+                self.dwarf.unit.add(self.dwarf.unit.root(), gimli::DW_TAG_array_type);
+            let array_type_entry = self.dwarf.unit.get_mut(array_type_id);
+            array_type_entry
+                .set(gimli::DW_AT_type, AttributeValue::UnitRef(self.placeholder_types.u8_type));
+
+            let subrange_id = self.dwarf.unit.add(array_type_id, gimli::DW_TAG_subrange_type);
+            let subrange_entry = self.dwarf.unit.get_mut(subrange_id);
+            subrange_entry.set(gimli::DW_AT_type, AttributeValue::UnitRef(self.array_size_type));
+            subrange_entry.set(gimli::DW_AT_lower_bound, AttributeValue::Udata(0));
+            subrange_entry.set(gimli::DW_AT_count, AttributeValue::Udata(size));
+
+            array_type_id
+        })
+    }
+}