src/debuginfo/mod.rs

   1 //! Handling of everything related to debuginfo.
   2
   3 mod emit;
   4 mod line_info;
   5 mod object;
   6 mod unwind;
   7
   8 use crate::prelude::*;
   9
  10 use rustc_index::vec::IndexVec;
  11
  12 use cranelift_codegen::entity::EntityRef;
  13 use cranelift_codegen::ir::{LabelValueLoc, ValueLabel};
  14 use cranelift_codegen::isa::TargetIsa;
  15 use cranelift_codegen::ValueLocRange;
  16
  17 use gimli::write::{
  18     Address, AttributeValue, DwarfUnit, Expression, LineProgram, LineString, Location,
  19     LocationList, Range, RangeList, UnitEntryId,
  20 };
  21 use gimli::{Encoding, Format, LineEncoding, RunTimeEndian, X86_64};
  22
  23 pub(crate) use emit::{DebugReloc, DebugRelocName};
  24 pub(crate) use unwind::UnwindContext;
  25
  26 fn target_endian(tcx: TyCtxt<'_>) -> RunTimeEndian {
  27     use rustc_target::abi::Endian;
  28
  29     match tcx.data_layout.endian {
  30         Endian::Big => RunTimeEndian::Big,
  31         Endian::Little => RunTimeEndian::Little,
  32     }
  33 }
  34
  35 pub(crate) struct DebugContext<'tcx> {
  36     tcx: TyCtxt<'tcx>,
  37
  38     endian: RunTimeEndian,
  39
  40     dwarf: DwarfUnit,
  41     unit_range_list: RangeList,
  42
  43     types: FxHashMap<Ty<'tcx>, UnitEntryId>,
  44 }
  45
  46 impl<'tcx> DebugContext<'tcx> {
  47     pub(crate) fn new(tcx: TyCtxt<'tcx>, isa: &dyn TargetIsa) -> Self {
  48         let encoding = Encoding {
  49             format: Format::Dwarf32,
  50             // FIXME this should be configurable
  51             // macOS doesn't seem to support DWARF > 3
  52             // 5 version is required for md5 file hash
  53             version: if tcx.sess.target.is_like_osx {
  54                 3
  55             } else {
  56                 // FIXME change to version 5 once the gdb and lldb shipping with the latest debian
  57                 // support it.
  58                 4
  59             },
  60             address_size: isa.frontend_config().pointer_bytes(),
  61         };
  62
  63         let mut dwarf = DwarfUnit::new(encoding);
  64
  65         let producer = format!(
  66             "cg_clif (rustc {}, cranelift {})",
  67             rustc_interface::util::version_str().unwrap_or("unknown version"),
  68             cranelift_codegen::VERSION,
  69         );
  70         let comp_dir = tcx
  71             .sess
  72             .opts
  73             .working_dir
  74             .to_string_lossy(FileNameDisplayPreference::Remapped)
  75             .into_owned();
  76         let (name, file_info) = match tcx.sess.local_crate_source_file.clone() {
  77             Some(path) => {
  78                 let name = path.to_string_lossy().into_owned();
  79                 (name, None)
  80             }
  81             None => (tcx.crate_name(LOCAL_CRATE).to_string(), None),
  82         };
  83
  84         let mut line_program = LineProgram::new(
  85             encoding,
  86             LineEncoding::default(),
  87             LineString::new(comp_dir.as_bytes(), encoding, &mut dwarf.line_strings),
  88             LineString::new(name.as_bytes(), encoding, &mut dwarf.line_strings),
  89             file_info,
  90         );
  91         line_program.file_has_md5 = file_info.is_some();
  92
  93         dwarf.unit.line_program = line_program;
  94
  95         {
  96             let name = dwarf.strings.add(name);
  97             let comp_dir = dwarf.strings.add(comp_dir);
  98
  99             let root = dwarf.unit.root();
 100             let root = dwarf.unit.get_mut(root);
 101             root.set(gimli::DW_AT_producer, AttributeValue::StringRef(dwarf.strings.add(producer)));
 102             root.set(gimli::DW_AT_language, AttributeValue::Language(gimli::DW_LANG_Rust));
 103             root.set(gimli::DW_AT_name, AttributeValue::StringRef(name));
 104             root.set(gimli::DW_AT_comp_dir, AttributeValue::StringRef(comp_dir));
 105             root.set(gimli::DW_AT_low_pc, AttributeValue::Address(Address::Constant(0)));
 106         }
 107
 108         DebugContext {
 109             tcx,
 110
 111             endian: target_endian(tcx),
 112
 113             dwarf,
 114             unit_range_list: RangeList(Vec::new()),
 115
 116             types: FxHashMap::default(),
 117         }
 118     }
 119
 120     fn dwarf_ty(&mut self, ty: Ty<'tcx>) -> UnitEntryId {
 121         if let Some(type_id) = self.types.get(ty) {
 122             return *type_id;
 123         }
 124
 125         let new_entry = |dwarf: &mut DwarfUnit, tag| dwarf.unit.add(dwarf.unit.root(), tag);
 126
 127         let primitive = |dwarf: &mut DwarfUnit, ate| {
 128             let type_id = new_entry(dwarf, gimli::DW_TAG_base_type);
 129             let type_entry = dwarf.unit.get_mut(type_id);
 130             type_entry.set(gimli::DW_AT_encoding, AttributeValue::Encoding(ate));
 131             type_id
 132         };
 133
 134         let name = format!("{}", ty);
 135         let layout = self.tcx.layout_of(ParamEnv::reveal_all().and(ty)).unwrap();
 136
 137         let type_id = match ty.kind() {
 138             ty::Bool => primitive(&mut self.dwarf, gimli::DW_ATE_boolean),
 139             ty::Char => primitive(&mut self.dwarf, gimli::DW_ATE_UTF),
 140             ty::Uint(_) => primitive(&mut self.dwarf, gimli::DW_ATE_unsigned),
 141             ty::Int(_) => primitive(&mut self.dwarf, gimli::DW_ATE_signed),
 142             ty::Float(_) => primitive(&mut self.dwarf, gimli::DW_ATE_float),
 143             ty::Ref(_, pointee_ty, _mutbl)
 144             | ty::RawPtr(ty::TypeAndMut { ty: pointee_ty, mutbl: _mutbl }) => {
 145                 let type_id = new_entry(&mut self.dwarf, gimli::DW_TAG_pointer_type);
 146
 147                 // Ensure that type is inserted before recursing to avoid duplicates
 148                 self.types.insert(ty, type_id);
 149
 150                 let pointee = self.dwarf_ty(pointee_ty);
 151
 152                 let type_entry = self.dwarf.unit.get_mut(type_id);
 153
 154                 //type_entry.set(gimli::DW_AT_mutable, AttributeValue::Flag(mutbl == rustc_hir::Mutability::Mut));
 155                 type_entry.set(gimli::DW_AT_type, AttributeValue::UnitRef(pointee));
 156
 157                 type_id
 158             }
 159             ty::Adt(adt_def, _substs) if adt_def.is_struct() && !layout.is_unsized() => {
 160                 let type_id = new_entry(&mut self.dwarf, gimli::DW_TAG_structure_type);
 161
 162                 // Ensure that type is inserted before recursing to avoid duplicates
 163                 self.types.insert(ty, type_id);
 164
 165                 let variant = adt_def.non_enum_variant();
 166
 167                 for (field_idx, field_def) in variant.fields.iter().enumerate() {
 168                     let field_offset = layout.fields.offset(field_idx);
 169                     let field_layout = layout.field(
 170                         &layout::LayoutCx { tcx: self.tcx, param_env: ParamEnv::reveal_all() },
 171                         field_idx,
 172                     );
 173
 174                     let field_type = self.dwarf_ty(field_layout.ty);
 175
 176                     let field_id = self.dwarf.unit.add(type_id, gimli::DW_TAG_member);
 177                     let field_entry = self.dwarf.unit.get_mut(field_id);
 178
 179                     field_entry.set(
 180                         gimli::DW_AT_name,
 181                         AttributeValue::String(field_def.ident.as_str().to_string().into_bytes()),
 182                     );
 183                     field_entry.set(
 184                         gimli::DW_AT_data_member_location,
 185                         AttributeValue::Udata(field_offset.bytes()),
 186                     );
 187                     field_entry.set(gimli::DW_AT_type, AttributeValue::UnitRef(field_type));
 188                 }
 189
 190                 type_id
 191             }
 192             _ => new_entry(&mut self.dwarf, gimli::DW_TAG_structure_type),
 193         };
 194
 195         let type_entry = self.dwarf.unit.get_mut(type_id);
 196
 197         type_entry.set(gimli::DW_AT_name, AttributeValue::String(name.into_bytes()));
 198         type_entry.set(gimli::DW_AT_byte_size, AttributeValue::Udata(layout.size.bytes()));
 199
 200         self.types.insert(ty, type_id);
 201
 202         type_id
 203     }
 204
 205     fn define_local(&mut self, scope: UnitEntryId, name: String, ty: Ty<'tcx>) -> UnitEntryId {
 206         let dw_ty = self.dwarf_ty(ty);
 207
 208         let var_id = self.dwarf.unit.add(scope, gimli::DW_TAG_variable);
 209         let var_entry = self.dwarf.unit.get_mut(var_id);
 210
 211         var_entry.set(gimli::DW_AT_name, AttributeValue::String(name.into_bytes()));
 212         var_entry.set(gimli::DW_AT_type, AttributeValue::UnitRef(dw_ty));
 213
 214         var_id
 215     }
 216
 217     pub(crate) fn define_function(
 218         &mut self,
 219         instance: Instance<'tcx>,
 220         func_id: FuncId,
 221         name: &str,
 222         isa: &dyn TargetIsa,
 223         context: &Context,
 224         source_info_set: &indexmap::IndexSet<SourceInfo>,
 225         local_map: IndexVec<mir::Local, CPlace<'tcx>>,
 226     ) {
 227         let symbol = func_id.as_u32() as usize;
 228         let mir = self.tcx.instance_mir(instance.def);
 229
 230         // FIXME: add to appropriate scope instead of root
 231         let scope = self.dwarf.unit.root();
 232
 233         let entry_id = self.dwarf.unit.add(scope, gimli::DW_TAG_subprogram);
 234         let entry = self.dwarf.unit.get_mut(entry_id);
 235         let name_id = self.dwarf.strings.add(name);
 236         // Gdb requires DW_AT_name. Otherwise the DW_TAG_subprogram is skipped.
 237         entry.set(gimli::DW_AT_name, AttributeValue::StringRef(name_id));
 238         entry.set(gimli::DW_AT_linkage_name, AttributeValue::StringRef(name_id));
 239
 240         let end = self.create_debug_lines(symbol, entry_id, context, mir.span, source_info_set);
 241
 242         self.unit_range_list.0.push(Range::StartLength {
 243             begin: Address::Symbol { symbol, addend: 0 },
 244             length: u64::from(end),
 245         });
 246
 247         let func_entry = self.dwarf.unit.get_mut(entry_id);
 248         // Gdb requires both DW_AT_low_pc and DW_AT_high_pc. Otherwise the DW_TAG_subprogram is skipped.
 249         func_entry.set(
 250             gimli::DW_AT_low_pc,
 251             AttributeValue::Address(Address::Symbol { symbol, addend: 0 }),
 252         );
 253         // Using Udata for DW_AT_high_pc requires at least DWARF4
 254         func_entry.set(gimli::DW_AT_high_pc, AttributeValue::Udata(u64::from(end)));
 255
 256         // FIXME make it more reliable and implement scopes before re-enabling this.
 257         if false {
 258             let value_labels_ranges = std::collections::HashMap::new(); // FIXME
 259
 260             for (local, _local_decl) in mir.local_decls.iter_enumerated() {
 261                 let ty = self.tcx.subst_and_normalize_erasing_regions(
 262                     instance.substs,
 263                     ty::ParamEnv::reveal_all(),
 264                     mir.local_decls[local].ty,
 265                 );
 266                 let var_id = self.define_local(entry_id, format!("{:?}", local), ty);
 267
 268                 let location = place_location(
 269                     self,
 270                     isa,
 271                     symbol,
 272                     &local_map,
 273                     &value_labels_ranges,
 274                     Place { local, projection: ty::List::empty() },
 275                 );
 276
 277                 let var_entry = self.dwarf.unit.get_mut(var_id);
 278                 var_entry.set(gimli::DW_AT_location, location);
 279             }
 280         }
 281
 282         // FIXME create locals for all entries in mir.var_debug_info
 283     }
 284 }
 285
 286 fn place_location<'tcx>(
 287     debug_context: &mut DebugContext<'tcx>,
 288     isa: &dyn TargetIsa,
 289     symbol: usize,
 290     local_map: &IndexVec<mir::Local, CPlace<'tcx>>,
 291     #[allow(rustc::default_hash_types)] value_labels_ranges: &std::collections::HashMap<
 292         ValueLabel,
 293         Vec<ValueLocRange>,
 294     >,
 295     place: Place<'tcx>,
 296 ) -> AttributeValue {
 297     assert!(place.projection.is_empty()); // FIXME implement them
 298
 299     match local_map[place.local].inner() {
 300         CPlaceInner::Var(_local, var) => {
 301             let value_label = cranelift_codegen::ir::ValueLabel::new(var.index());
 302             if let Some(value_loc_ranges) = value_labels_ranges.get(&value_label) {
 303                 let loc_list = LocationList(
 304                     value_loc_ranges
 305                         .iter()
 306                         .map(|value_loc_range| Location::StartEnd {
 307                             begin: Address::Symbol {
 308                                 symbol,
 309                                 addend: i64::from(value_loc_range.start),
 310                             },
 311                             end: Address::Symbol { symbol, addend: i64::from(value_loc_range.end) },
 312                             data: translate_loc(isa, value_loc_range.loc).unwrap(),
 313                         })
 314                         .collect(),
 315                 );
 316                 let loc_list_id = debug_context.dwarf.unit.locations.add(loc_list);
 317
 318                 AttributeValue::LocationListRef(loc_list_id)
 319             } else {
 320                 // FIXME set value labels for unused locals
 321
 322                 AttributeValue::Exprloc(Expression::new())
 323             }
 324         }
 325         CPlaceInner::VarPair(_, _, _) => {
 326             // FIXME implement this
 327
 328             AttributeValue::Exprloc(Expression::new())
 329         }
 330         CPlaceInner::VarLane(_, _, _) => {
 331             // FIXME implement this
 332
 333             AttributeValue::Exprloc(Expression::new())
 334         }
 335         CPlaceInner::Addr(_, _) => {
 336             // FIXME implement this (used by arguments and returns)
 337
 338             AttributeValue::Exprloc(Expression::new())
 339
 340             // For PointerBase::Stack:
 341             //AttributeValue::Exprloc(translate_loc(ValueLoc::Stack(*stack_slot)).unwrap())
 342         }
 343     }
 344 }
 345
 346 // Adapted from https://github.com/CraneStation/wasmtime/blob/5a1845b4caf7a5dba8eda1fef05213a532ed4259/crates/debug/src/transform/expression.rs#L59-L137
 347 fn translate_loc(isa: &dyn TargetIsa, loc: LabelValueLoc) -> Option<Expression> {
 348     match loc {
 349         LabelValueLoc::Reg(reg) => {
 350             let machine_reg = isa.map_regalloc_reg_to_dwarf(reg).unwrap();
 351             let mut expr = Expression::new();
 352             expr.op_reg(gimli::Register(machine_reg));
 353             Some(expr)
 354         }
 355         LabelValueLoc::SPOffset(offset) => {
 356             let mut expr = Expression::new();
 357             expr.op_breg(X86_64::RSP, offset);
 358             Some(expr)
 359         }
 360     }
 361 }