src/librustc_trans/debuginfo/metadata.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use self::RecursiveTypeDescription::*;
  12 use self::MemberOffset::*;
  13 use self::MemberDescriptionFactory::*;
  14 use self::EnumDiscriminantInfo::*;
  15
  16 use super::utils::{debug_context, DIB, span_start, bytes_to_bits, size_and_align_of,
  17                    get_namespace_and_span_for_item, create_DIArray, is_node_local_to_unit};
  18 use super::namespace::mangled_name_of_item;
  19 use super::type_names::compute_debuginfo_type_name;
  20 use super::{CrateDebugContext};
  21 use context::SharedCrateContext;
  22 use session::Session;
  23
  24 use llvm::{self, ValueRef};
  25 use llvm::debuginfo::{DIType, DIFile, DIScope, DIDescriptor,
  26                       DICompositeType, DILexicalBlock, DIFlags};
  27
  28 use rustc::hir::def::CtorKind;
  29 use rustc::hir::def_id::DefId;
  30 use rustc::ty::fold::TypeVisitor;
  31 use rustc::ty::subst::Substs;
  32 use rustc::ty::util::TypeIdHasher;
  33 use rustc::hir;
  34 use rustc_data_structures::ToHex;
  35 use {type_of, machine, monomorphize};
  36 use common::CrateContext;
  37 use type_::Type;
  38 use rustc::ty::{self, AdtKind, Ty, layout};
  39 use session::config;
  40 use util::nodemap::FxHashMap;
  41 use util::common::path2cstr;
  42
  43 use libc::{c_uint, c_longlong};
  44 use std::ffi::CString;
  45 use std::path::Path;
  46 use std::ptr;
  47 use syntax::ast;
  48 use syntax::symbol::{Interner, InternedString};
  49 use syntax_pos::{self, Span};
  50
  51
  52 // From DWARF 5.
  53 // See http://www.dwarfstd.org/ShowIssue.php?issue=140129.1
  54 const DW_LANG_RUST: c_uint = 0x1c;
  55 #[allow(non_upper_case_globals)]
  56 const DW_ATE_boolean: c_uint = 0x02;
  57 #[allow(non_upper_case_globals)]
  58 const DW_ATE_float: c_uint = 0x04;
  59 #[allow(non_upper_case_globals)]
  60 const DW_ATE_signed: c_uint = 0x05;
  61 #[allow(non_upper_case_globals)]
  62 const DW_ATE_unsigned: c_uint = 0x07;
  63 #[allow(non_upper_case_globals)]
  64 const DW_ATE_unsigned_char: c_uint = 0x08;
  65
  66 pub const UNKNOWN_LINE_NUMBER: c_uint = 0;
  67 pub const UNKNOWN_COLUMN_NUMBER: c_uint = 0;
  68
  69 // ptr::null() doesn't work :(
  70 pub const NO_SCOPE_METADATA: DIScope = (0 as DIScope);
  71
  72 #[derive(Copy, Debug, Hash, Eq, PartialEq, Clone)]
  73 pub struct UniqueTypeId(ast::Name);
  74
  75 // The TypeMap is where the CrateDebugContext holds the type metadata nodes
  76 // created so far. The metadata nodes are indexed by UniqueTypeId, and, for
  77 // faster lookup, also by Ty. The TypeMap is responsible for creating
  78 // UniqueTypeIds.
  79 pub struct TypeMap<'tcx> {
  80     // The UniqueTypeIds created so far
  81     unique_id_interner: Interner,
  82     // A map from UniqueTypeId to debuginfo metadata for that type. This is a 1:1 mapping.
  83     unique_id_to_metadata: FxHashMap<UniqueTypeId, DIType>,
  84     // A map from types to debuginfo metadata. This is a N:1 mapping.
  85     type_to_metadata: FxHashMap<Ty<'tcx>, DIType>,
  86     // A map from types to UniqueTypeId. This is a N:1 mapping.
  87     type_to_unique_id: FxHashMap<Ty<'tcx>, UniqueTypeId>
  88 }
  89
  90 impl<'tcx> TypeMap<'tcx> {
  91     pub fn new() -> TypeMap<'tcx> {
  92         TypeMap {
  93             unique_id_interner: Interner::new(),
  94             type_to_metadata: FxHashMap(),
  95             unique_id_to_metadata: FxHashMap(),
  96             type_to_unique_id: FxHashMap(),
  97         }
  98     }
  99
 100     // Adds a Ty to metadata mapping to the TypeMap. The method will fail if
 101     // the mapping already exists.
 102     fn register_type_with_metadata<'a>(&mut self,
 103                                        type_: Ty<'tcx>,
 104                                        metadata: DIType) {
 105         if self.type_to_metadata.insert(type_, metadata).is_some() {
 106             bug!("Type metadata for Ty '{}' is already in the TypeMap!", type_);
 107         }
 108     }
 109
 110     // Adds a UniqueTypeId to metadata mapping to the TypeMap. The method will
 111     // fail if the mapping already exists.
 112     fn register_unique_id_with_metadata(&mut self,
 113                                         unique_type_id: UniqueTypeId,
 114                                         metadata: DIType) {
 115         if self.unique_id_to_metadata.insert(unique_type_id, metadata).is_some() {
 116             bug!("Type metadata for unique id '{}' is already in the TypeMap!",
 117                  self.get_unique_type_id_as_string(unique_type_id));
 118         }
 119     }
 120
 121     fn find_metadata_for_type(&self, type_: Ty<'tcx>) -> Option<DIType> {
 122         self.type_to_metadata.get(&type_).cloned()
 123     }
 124
 125     fn find_metadata_for_unique_id(&self, unique_type_id: UniqueTypeId) -> Option<DIType> {
 126         self.unique_id_to_metadata.get(&unique_type_id).cloned()
 127     }
 128
 129     // Get the string representation of a UniqueTypeId. This method will fail if
 130     // the id is unknown.
 131     fn get_unique_type_id_as_string(&self, unique_type_id: UniqueTypeId) -> &str {
 132         let UniqueTypeId(interner_key) = unique_type_id;
 133         self.unique_id_interner.get(interner_key)
 134     }
 135
 136     // Get the UniqueTypeId for the given type. If the UniqueTypeId for the given
 137     // type has been requested before, this is just a table lookup. Otherwise an
 138     // ID will be generated and stored for later lookup.
 139     fn get_unique_type_id_of_type<'a>(&mut self, cx: &CrateContext<'a, 'tcx>,
 140                                       type_: Ty<'tcx>) -> UniqueTypeId {
 141         // Let's see if we already have something in the cache
 142         match self.type_to_unique_id.get(&type_).cloned() {
 143             Some(unique_type_id) => return unique_type_id,
 144             None => { /* generate one */}
 145         };
 146
 147         // The hasher we are using to generate the UniqueTypeId. We want
 148         // something that provides more than the 64 bits of the DefaultHasher.
 149
 150         let mut type_id_hasher = TypeIdHasher::<[u8; 20]>::new(cx.tcx());
 151         type_id_hasher.visit_ty(type_);
 152
 153         let unique_type_id = type_id_hasher.finish().to_hex();
 154         let key = self.unique_id_interner.intern(&unique_type_id);
 155         self.type_to_unique_id.insert(type_, UniqueTypeId(key));
 156
 157         return UniqueTypeId(key);
 158     }
 159
 160     // Get the UniqueTypeId for an enum variant. Enum variants are not really
 161     // types of their own, so they need special handling. We still need a
 162     // UniqueTypeId for them, since to debuginfo they *are* real types.
 163     fn get_unique_type_id_of_enum_variant<'a>(&mut self,
 164                                               cx: &CrateContext<'a, 'tcx>,
 165                                               enum_type: Ty<'tcx>,
 166                                               variant_name: &str)
 167                                               -> UniqueTypeId {
 168         let enum_type_id = self.get_unique_type_id_of_type(cx, enum_type);
 169         let enum_variant_type_id = format!("{}::{}",
 170                                            self.get_unique_type_id_as_string(enum_type_id),
 171                                            variant_name);
 172         let interner_key = self.unique_id_interner.intern(&enum_variant_type_id);
 173         UniqueTypeId(interner_key)
 174     }
 175 }
 176
 177 // A description of some recursive type. It can either be already finished (as
 178 // with FinalMetadata) or it is not yet finished, but contains all information
 179 // needed to generate the missing parts of the description. See the
 180 // documentation section on Recursive Types at the top of this file for more
 181 // information.
 182 enum RecursiveTypeDescription<'tcx> {
 183     UnfinishedMetadata {
 184         unfinished_type: Ty<'tcx>,
 185         unique_type_id: UniqueTypeId,
 186         metadata_stub: DICompositeType,
 187         llvm_type: Type,
 188         member_description_factory: MemberDescriptionFactory<'tcx>,
 189     },
 190     FinalMetadata(DICompositeType)
 191 }
 192
 193 fn create_and_register_recursive_type_forward_declaration<'a, 'tcx>(
 194     cx: &CrateContext<'a, 'tcx>,
 195     unfinished_type: Ty<'tcx>,
 196     unique_type_id: UniqueTypeId,
 197     metadata_stub: DICompositeType,
 198     llvm_type: Type,
 199     member_description_factory: MemberDescriptionFactory<'tcx>)
 200  -> RecursiveTypeDescription<'tcx> {
 201
 202     // Insert the stub into the TypeMap in order to allow for recursive references
 203     let mut type_map = debug_context(cx).type_map.borrow_mut();
 204     type_map.register_unique_id_with_metadata(unique_type_id, metadata_stub);
 205     type_map.register_type_with_metadata(unfinished_type, metadata_stub);
 206
 207     UnfinishedMetadata {
 208         unfinished_type: unfinished_type,
 209         unique_type_id: unique_type_id,
 210         metadata_stub: metadata_stub,
 211         llvm_type: llvm_type,
 212         member_description_factory: member_description_factory,
 213     }
 214 }
 215
 216 impl<'tcx> RecursiveTypeDescription<'tcx> {
 217     // Finishes up the description of the type in question (mostly by providing
 218     // descriptions of the fields of the given type) and returns the final type
 219     // metadata.
 220     fn finalize<'a>(&self, cx: &CrateContext<'a, 'tcx>) -> MetadataCreationResult {
 221         match *self {
 222             FinalMetadata(metadata) => MetadataCreationResult::new(metadata, false),
 223             UnfinishedMetadata {
 224                 unfinished_type,
 225                 unique_type_id,
 226                 metadata_stub,
 227                 llvm_type,
 228                 ref member_description_factory,
 229                 ..
 230             } => {
 231                 // Make sure that we have a forward declaration of the type in
 232                 // the TypeMap so that recursive references are possible. This
 233                 // will always be the case if the RecursiveTypeDescription has
 234                 // been properly created through the
 235                 // create_and_register_recursive_type_forward_declaration()
 236                 // function.
 237                 {
 238                     let type_map = debug_context(cx).type_map.borrow();
 239                     if type_map.find_metadata_for_unique_id(unique_type_id).is_none() ||
 240                        type_map.find_metadata_for_type(unfinished_type).is_none() {
 241                         bug!("Forward declaration of potentially recursive type \
 242                               '{:?}' was not found in TypeMap!",
 243                              unfinished_type);
 244                     }
 245                 }
 246
 247                 // ... then create the member descriptions ...
 248                 let member_descriptions =
 249                     member_description_factory.create_member_descriptions(cx);
 250
 251                 // ... and attach them to the stub to complete it.
 252                 set_members_of_composite_type(cx,
 253                                               metadata_stub,
 254                                               llvm_type,
 255                                               &member_descriptions[..]);
 256                 return MetadataCreationResult::new(metadata_stub, true);
 257             }
 258         }
 259     }
 260 }
 261
 262 // Returns from the enclosing function if the type metadata with the given
 263 // unique id can be found in the type map
 264 macro_rules! return_if_metadata_created_in_meantime {
 265     ($cx: expr, $unique_type_id: expr) => (
 266         match debug_context($cx).type_map
 267                                 .borrow()
 268                                 .find_metadata_for_unique_id($unique_type_id) {
 269             Some(metadata) => return MetadataCreationResult::new(metadata, true),
 270             None => { /* proceed normally */ }
 271         }
 272     )
 273 }
 274
 275 fn fixed_vec_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 276                                 unique_type_id: UniqueTypeId,
 277                                 element_type: Ty<'tcx>,
 278                                 len: Option<u64>,
 279                                 span: Span)
 280                                 -> MetadataCreationResult {
 281     let element_type_metadata = type_metadata(cx, element_type, span);
 282
 283     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 284
 285     let element_llvm_type = type_of::type_of(cx, element_type);
 286     let (element_type_size, element_type_align) = size_and_align_of(cx, element_llvm_type);
 287
 288     let (array_size_in_bytes, upper_bound) = match len {
 289         Some(len) => (element_type_size * len, len as c_longlong),
 290         None => (0, -1)
 291     };
 292
 293     let subrange = unsafe {
 294         llvm::LLVMRustDIBuilderGetOrCreateSubrange(DIB(cx), 0, upper_bound)
 295     };
 296
 297     let subscripts = create_DIArray(DIB(cx), &[subrange]);
 298     let metadata = unsafe {
 299         llvm::LLVMRustDIBuilderCreateArrayType(
 300             DIB(cx),
 301             bytes_to_bits(array_size_in_bytes),
 302             bytes_to_bits(element_type_align),
 303             element_type_metadata,
 304             subscripts)
 305     };
 306
 307     return MetadataCreationResult::new(metadata, false);
 308 }
 309
 310 fn vec_slice_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 311                                 vec_type: Ty<'tcx>,
 312                                 element_type: Ty<'tcx>,
 313                                 unique_type_id: UniqueTypeId,
 314                                 span: Span)
 315                                 -> MetadataCreationResult {
 316     let data_ptr_type = cx.tcx().mk_ptr(ty::TypeAndMut {
 317         ty: element_type,
 318         mutbl: hir::MutImmutable
 319     });
 320
 321     let element_type_metadata = type_metadata(cx, data_ptr_type, span);
 322
 323     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 324
 325     let slice_llvm_type = type_of::type_of(cx, vec_type);
 326     let slice_type_name = compute_debuginfo_type_name(cx, vec_type, true);
 327
 328     let member_llvm_types = slice_llvm_type.field_types();
 329     assert!(slice_layout_is_correct(cx,
 330                                     &member_llvm_types[..],
 331                                     element_type));
 332     let member_descriptions = [
 333         MemberDescription {
 334             name: "data_ptr".to_string(),
 335             llvm_type: member_llvm_types[0],
 336             type_metadata: element_type_metadata,
 337             offset: ComputedMemberOffset,
 338             flags: DIFlags::FlagZero,
 339         },
 340         MemberDescription {
 341             name: "length".to_string(),
 342             llvm_type: member_llvm_types[1],
 343             type_metadata: type_metadata(cx, cx.tcx().types.usize, span),
 344             offset: ComputedMemberOffset,
 345             flags: DIFlags::FlagZero,
 346         },
 347     ];
 348
 349     assert!(member_descriptions.len() == member_llvm_types.len());
 350
 351     let loc = span_start(cx, span);
 352     let file_metadata = file_metadata(cx, &loc.file.name, &loc.file.abs_path);
 353
 354     let metadata = composite_type_metadata(cx,
 355                                            slice_llvm_type,
 356                                            &slice_type_name[..],
 357                                            unique_type_id,
 358                                            &member_descriptions,
 359                                            NO_SCOPE_METADATA,
 360                                            file_metadata,
 361                                            span);
 362     return MetadataCreationResult::new(metadata, false);
 363
 364     fn slice_layout_is_correct<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 365                                          member_llvm_types: &[Type],
 366                                          element_type: Ty<'tcx>)
 367                                          -> bool {
 368         member_llvm_types.len() == 2 &&
 369         member_llvm_types[0] == type_of::type_of(cx, element_type).ptr_to() &&
 370         member_llvm_types[1] == cx.int_type()
 371     }
 372 }
 373
 374 fn subroutine_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 375                                       unique_type_id: UniqueTypeId,
 376                                       signature: &ty::PolyFnSig<'tcx>,
 377                                       span: Span)
 378                                       -> MetadataCreationResult
 379 {
 380     let signature = cx.tcx().erase_late_bound_regions(signature);
 381
 382     let mut signature_metadata: Vec<DIType> = Vec::with_capacity(signature.inputs().len() + 1);
 383
 384     // return type
 385     signature_metadata.push(match signature.output().sty {
 386         ty::TyTuple(ref tys, _) if tys.is_empty() => ptr::null_mut(),
 387         _ => type_metadata(cx, signature.output(), span)
 388     });
 389
 390     // regular arguments
 391     for &argument_type in signature.inputs() {
 392         signature_metadata.push(type_metadata(cx, argument_type, span));
 393     }
 394
 395     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 396
 397     return MetadataCreationResult::new(
 398         unsafe {
 399             llvm::LLVMRustDIBuilderCreateSubroutineType(
 400                 DIB(cx),
 401                 unknown_file_metadata(cx),
 402                 create_DIArray(DIB(cx), &signature_metadata[..]))
 403         },
 404         false);
 405 }
 406
 407 // FIXME(1563) This is all a bit of a hack because 'trait pointer' is an ill-
 408 // defined concept. For the case of an actual trait pointer (i.e., Box<Trait>,
 409 // &Trait), trait_object_type should be the whole thing (e.g, Box<Trait>) and
 410 // trait_type should be the actual trait (e.g., Trait). Where the trait is part
 411 // of a DST struct, there is no trait_object_type and the results of this
 412 // function will be a little bit weird.
 413 fn trait_pointer_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 414                                     trait_type: Ty<'tcx>,
 415                                     trait_object_type: Option<Ty<'tcx>>,
 416                                     unique_type_id: UniqueTypeId)
 417                                     -> DIType {
 418     // The implementation provided here is a stub. It makes sure that the trait
 419     // type is assigned the correct name, size, namespace, and source location.
 420     // But it does not describe the trait's methods.
 421
 422     let containing_scope = match trait_type.sty {
 423         ty::TyDynamic(ref data, ..) => if let Some(principal) = data.principal() {
 424             let def_id = principal.def_id();
 425             get_namespace_and_span_for_item(cx, def_id).0
 426         } else {
 427             NO_SCOPE_METADATA
 428         },
 429         _ => {
 430             bug!("debuginfo: Unexpected trait-object type in \
 431                   trait_pointer_metadata(): {:?}",
 432                  trait_type);
 433         }
 434     };
 435
 436     let trait_object_type = trait_object_type.unwrap_or(trait_type);
 437     let trait_type_name =
 438         compute_debuginfo_type_name(cx, trait_object_type, false);
 439
 440     let trait_llvm_type = type_of::type_of(cx, trait_object_type);
 441     let file_metadata = unknown_file_metadata(cx);
 442
 443     composite_type_metadata(cx,
 444                             trait_llvm_type,
 445                             &trait_type_name[..],
 446                             unique_type_id,
 447                             &[],
 448                             containing_scope,
 449                             file_metadata,
 450                             syntax_pos::DUMMY_SP)
 451 }
 452
 453 pub fn type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 454                                t: Ty<'tcx>,
 455                                usage_site_span: Span)
 456                                -> DIType {
 457     // Get the unique type id of this type.
 458     let unique_type_id = {
 459         let mut type_map = debug_context(cx).type_map.borrow_mut();
 460         // First, try to find the type in TypeMap. If we have seen it before, we
 461         // can exit early here.
 462         match type_map.find_metadata_for_type(t) {
 463             Some(metadata) => {
 464                 return metadata;
 465             },
 466             None => {
 467                 // The Ty is not in the TypeMap but maybe we have already seen
 468                 // an equivalent type (e.g. only differing in region arguments).
 469                 // In order to find out, generate the unique type id and look
 470                 // that up.
 471                 let unique_type_id = type_map.get_unique_type_id_of_type(cx, t);
 472                 match type_map.find_metadata_for_unique_id(unique_type_id) {
 473                     Some(metadata) => {
 474                         // There is already an equivalent type in the TypeMap.
 475                         // Register this Ty as an alias in the cache and
 476                         // return the cached metadata.
 477                         type_map.register_type_with_metadata(t, metadata);
 478                         return metadata;
 479                     },
 480                     None => {
 481                         // There really is no type metadata for this type, so
 482                         // proceed by creating it.
 483                         unique_type_id
 484                     }
 485                 }
 486             }
 487         }
 488     };
 489
 490     debug!("type_metadata: {:?}", t);
 491
 492     let sty = &t.sty;
 493     let ptr_metadata = |ty: Ty<'tcx>| {
 494         match ty.sty {
 495             ty::TySlice(typ) => {
 496                 Ok(vec_slice_metadata(cx, t, typ, unique_type_id, usage_site_span))
 497             }
 498             ty::TyStr => {
 499                 Ok(vec_slice_metadata(cx, t, cx.tcx().types.u8, unique_type_id, usage_site_span))
 500             }
 501             ty::TyDynamic(..) => {
 502                 Ok(MetadataCreationResult::new(
 503                     trait_pointer_metadata(cx, ty, Some(t), unique_type_id),
 504                     false))
 505             }
 506             _ => {
 507                 let pointee_metadata = type_metadata(cx, ty, usage_site_span);
 508
 509                 match debug_context(cx).type_map
 510                                         .borrow()
 511                                         .find_metadata_for_unique_id(unique_type_id) {
 512                     Some(metadata) => return Err(metadata),
 513                     None => { /* proceed normally */ }
 514                 };
 515
 516                 Ok(MetadataCreationResult::new(pointer_type_metadata(cx, t, pointee_metadata),
 517                    false))
 518             }
 519         }
 520     };
 521
 522     let MetadataCreationResult { metadata, already_stored_in_typemap } = match *sty {
 523         ty::TyNever    |
 524         ty::TyBool     |
 525         ty::TyChar     |
 526         ty::TyInt(_)   |
 527         ty::TyUint(_)  |
 528         ty::TyFloat(_) => {
 529             MetadataCreationResult::new(basic_type_metadata(cx, t), false)
 530         }
 531         ty::TyTuple(ref elements, _) if elements.is_empty() => {
 532             MetadataCreationResult::new(basic_type_metadata(cx, t), false)
 533         }
 534         ty::TyArray(typ, len) => {
 535             fixed_vec_metadata(cx, unique_type_id, typ, Some(len as u64), usage_site_span)
 536         }
 537         ty::TySlice(typ) => {
 538             fixed_vec_metadata(cx, unique_type_id, typ, None, usage_site_span)
 539         }
 540         ty::TyStr => {
 541             fixed_vec_metadata(cx, unique_type_id, cx.tcx().types.i8, None, usage_site_span)
 542         }
 543         ty::TyDynamic(..) => {
 544             MetadataCreationResult::new(
 545                         trait_pointer_metadata(cx, t, None, unique_type_id),
 546             false)
 547         }
 548         ty::TyRawPtr(ty::TypeAndMut{ty, ..}) |
 549         ty::TyRef(_, ty::TypeAndMut{ty, ..}) => {
 550             match ptr_metadata(ty) {
 551                 Ok(res) => res,
 552                 Err(metadata) => return metadata,
 553             }
 554         }
 555         ty::TyAdt(def, _) if def.is_box() => {
 556             match ptr_metadata(t.boxed_ty()) {
 557                 Ok(res) => res,
 558                 Err(metadata) => return metadata,
 559             }
 560         }
 561         ty::TyFnDef(.., ref barefnty) | ty::TyFnPtr(ref barefnty) => {
 562             let fn_metadata = subroutine_type_metadata(cx,
 563                                                        unique_type_id,
 564                                                        &barefnty.sig,
 565                                                        usage_site_span).metadata;
 566             match debug_context(cx).type_map
 567                                    .borrow()
 568                                    .find_metadata_for_unique_id(unique_type_id) {
 569                 Some(metadata) => return metadata,
 570                 None => { /* proceed normally */ }
 571             };
 572
 573             // This is actually a function pointer, so wrap it in pointer DI
 574             MetadataCreationResult::new(pointer_type_metadata(cx, t, fn_metadata), false)
 575
 576         }
 577         ty::TyClosure(def_id, substs) => {
 578             let upvar_tys : Vec<_> = substs.upvar_tys(def_id, cx.tcx()).collect();
 579             prepare_tuple_metadata(cx,
 580                                    t,
 581                                    &upvar_tys,
 582                                    unique_type_id,
 583                                    usage_site_span).finalize(cx)
 584         }
 585         ty::TyAdt(def, ..) => match def.adt_kind() {
 586             AdtKind::Struct => {
 587                 prepare_struct_metadata(cx,
 588                                         t,
 589                                         unique_type_id,
 590                                         usage_site_span).finalize(cx)
 591             }
 592             AdtKind::Union => {
 593                 prepare_union_metadata(cx,
 594                                     t,
 595                                     unique_type_id,
 596                                     usage_site_span).finalize(cx)
 597             }
 598             AdtKind::Enum => {
 599                 prepare_enum_metadata(cx,
 600                                     t,
 601                                     def.did,
 602                                     unique_type_id,
 603                                     usage_site_span).finalize(cx)
 604             }
 605         },
 606         ty::TyTuple(ref elements, _) => {
 607             prepare_tuple_metadata(cx,
 608                                    t,
 609                                    &elements[..],
 610                                    unique_type_id,
 611                                    usage_site_span).finalize(cx)
 612         }
 613         _ => {
 614             bug!("debuginfo: unexpected type in type_metadata: {:?}", sty)
 615         }
 616     };
 617
 618     {
 619         let mut type_map = debug_context(cx).type_map.borrow_mut();
 620
 621         if already_stored_in_typemap {
 622             // Also make sure that we already have a TypeMap entry for the unique type id.
 623             let metadata_for_uid = match type_map.find_metadata_for_unique_id(unique_type_id) {
 624                 Some(metadata) => metadata,
 625                 None => {
 626                     span_bug!(usage_site_span,
 627                               "Expected type metadata for unique \
 628                                type id '{}' to already be in \
 629                                the debuginfo::TypeMap but it \
 630                                was not. (Ty = {})",
 631                               type_map.get_unique_type_id_as_string(unique_type_id),
 632                               t);
 633                 }
 634             };
 635
 636             match type_map.find_metadata_for_type(t) {
 637                 Some(metadata) => {
 638                     if metadata != metadata_for_uid {
 639                         span_bug!(usage_site_span,
 640                                   "Mismatch between Ty and \
 641                                    UniqueTypeId maps in \
 642                                    debuginfo::TypeMap. \
 643                                    UniqueTypeId={}, Ty={}",
 644                                   type_map.get_unique_type_id_as_string(unique_type_id),
 645                                   t);
 646                     }
 647                 }
 648                 None => {
 649                     type_map.register_type_with_metadata(t, metadata);
 650                 }
 651             }
 652         } else {
 653             type_map.register_type_with_metadata(t, metadata);
 654             type_map.register_unique_id_with_metadata(unique_type_id, metadata);
 655         }
 656     }
 657
 658     metadata
 659 }
 660
 661 pub fn file_metadata(cx: &CrateContext, path: &str, full_path: &Option<String>) -> DIFile {
 662     // FIXME (#9639): This needs to handle non-utf8 paths
 663     let work_dir = cx.sess().working_dir.to_str().unwrap();
 664     let file_name =
 665         full_path.as_ref().map(|p| p.as_str()).unwrap_or_else(|| {
 666             if path.starts_with(work_dir) {
 667                 &path[work_dir.len() + 1..path.len()]
 668             } else {
 669                 path
 670             }
 671         });
 672
 673     file_metadata_(cx, path, file_name, &work_dir)
 674 }
 675
 676 pub fn unknown_file_metadata(cx: &CrateContext) -> DIFile {
 677     // Regular filenames should not be empty, so we abuse an empty name as the
 678     // key for the special unknown file metadata
 679     file_metadata_(cx, "", "<unknown>", "")
 680
 681 }
 682
 683 fn file_metadata_(cx: &CrateContext, key: &str, file_name: &str, work_dir: &str) -> DIFile {
 684     if let Some(file_metadata) = debug_context(cx).created_files.borrow().get(key) {
 685         return *file_metadata;
 686     }
 687
 688     debug!("file_metadata: file_name: {}, work_dir: {}", file_name, work_dir);
 689
 690     let file_name = CString::new(file_name).unwrap();
 691     let work_dir = CString::new(work_dir).unwrap();
 692     let file_metadata = unsafe {
 693         llvm::LLVMRustDIBuilderCreateFile(DIB(cx), file_name.as_ptr(),
 694                                           work_dir.as_ptr())
 695     };
 696
 697     let mut created_files = debug_context(cx).created_files.borrow_mut();
 698     created_files.insert(key.to_string(), file_metadata);
 699     file_metadata
 700 }
 701
 702 fn basic_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 703                                  t: Ty<'tcx>) -> DIType {
 704
 705     debug!("basic_type_metadata: {:?}", t);
 706
 707     let (name, encoding) = match t.sty {
 708         ty::TyNever => ("!", DW_ATE_unsigned),
 709         ty::TyTuple(ref elements, _) if elements.is_empty() =>
 710             ("()", DW_ATE_unsigned),
 711         ty::TyBool => ("bool", DW_ATE_boolean),
 712         ty::TyChar => ("char", DW_ATE_unsigned_char),
 713         ty::TyInt(int_ty) => {
 714             (int_ty.ty_to_string(), DW_ATE_signed)
 715         },
 716         ty::TyUint(uint_ty) => {
 717             (uint_ty.ty_to_string(), DW_ATE_unsigned)
 718         },
 719         ty::TyFloat(float_ty) => {
 720             (float_ty.ty_to_string(), DW_ATE_float)
 721         },
 722         _ => bug!("debuginfo::basic_type_metadata - t is invalid type")
 723     };
 724
 725     let llvm_type = type_of::type_of(cx, t);
 726     let (size, align) = size_and_align_of(cx, llvm_type);
 727     let name = CString::new(name).unwrap();
 728     let ty_metadata = unsafe {
 729         llvm::LLVMRustDIBuilderCreateBasicType(
 730             DIB(cx),
 731             name.as_ptr(),
 732             bytes_to_bits(size),
 733             bytes_to_bits(align),
 734             encoding)
 735     };
 736
 737     return ty_metadata;
 738 }
 739
 740 fn pointer_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 741                                    pointer_type: Ty<'tcx>,
 742                                    pointee_type_metadata: DIType)
 743                                    -> DIType {
 744     let pointer_llvm_type = type_of::type_of(cx, pointer_type);
 745     let (pointer_size, pointer_align) = size_and_align_of(cx, pointer_llvm_type);
 746     let name = compute_debuginfo_type_name(cx, pointer_type, false);
 747     let name = CString::new(name).unwrap();
 748     let ptr_metadata = unsafe {
 749         llvm::LLVMRustDIBuilderCreatePointerType(
 750             DIB(cx),
 751             pointee_type_metadata,
 752             bytes_to_bits(pointer_size),
 753             bytes_to_bits(pointer_align),
 754             name.as_ptr())
 755     };
 756     return ptr_metadata;
 757 }
 758
 759 pub fn compile_unit_metadata(scc: &SharedCrateContext,
 760                              debug_context: &CrateDebugContext,
 761                              sess: &Session)
 762                              -> DIDescriptor {
 763     let work_dir = &sess.working_dir;
 764     let compile_unit_name = match sess.local_crate_source_file {
 765         None => fallback_path(scc),
 766         Some(ref abs_path) => {
 767             if abs_path.is_relative() {
 768                 sess.warn("debuginfo: Invalid path to crate's local root source file!");
 769                 fallback_path(scc)
 770             } else {
 771                 match abs_path.strip_prefix(work_dir) {
 772                     Ok(ref p) if p.is_relative() => {
 773                         if p.starts_with(Path::new("./")) {
 774                             path2cstr(p)
 775                         } else {
 776                             path2cstr(&Path::new(".").join(p))
 777                         }
 778                     }
 779                     _ => fallback_path(scc)
 780                 }
 781             }
 782         }
 783     };
 784
 785     debug!("compile_unit_metadata: {:?}", compile_unit_name);
 786     let producer = format!("rustc version {}",
 787                            (option_env!("CFG_VERSION")).expect("CFG_VERSION"));
 788
 789     let compile_unit_name = compile_unit_name.as_ptr();
 790     let work_dir = path2cstr(&work_dir);
 791     let producer = CString::new(producer).unwrap();
 792     let flags = "\0";
 793     let split_name = "\0";
 794     return unsafe {
 795         llvm::LLVMRustDIBuilderCreateCompileUnit(
 796             debug_context.builder,
 797             DW_LANG_RUST,
 798             compile_unit_name,
 799             work_dir.as_ptr(),
 800             producer.as_ptr(),
 801             sess.opts.optimize != config::OptLevel::No,
 802             flags.as_ptr() as *const _,
 803             0,
 804             split_name.as_ptr() as *const _)
 805     };
 806
 807     fn fallback_path(scc: &SharedCrateContext) -> CString {
 808         CString::new(scc.link_meta().crate_name.to_string()).unwrap()
 809     }
 810 }
 811
 812 struct MetadataCreationResult {
 813     metadata: DIType,
 814     already_stored_in_typemap: bool
 815 }
 816
 817 impl MetadataCreationResult {
 818     fn new(metadata: DIType, already_stored_in_typemap: bool) -> MetadataCreationResult {
 819         MetadataCreationResult {
 820             metadata: metadata,
 821             already_stored_in_typemap: already_stored_in_typemap
 822         }
 823     }
 824 }
 825
 826 #[derive(Debug)]
 827 enum MemberOffset {
 828     FixedMemberOffset { bytes: usize },
 829     // For ComputedMemberOffset, the offset is read from the llvm type definition.
 830     ComputedMemberOffset
 831 }
 832
 833 // Description of a type member, which can either be a regular field (as in
 834 // structs or tuples) or an enum variant.
 835 #[derive(Debug)]
 836 struct MemberDescription {
 837     name: String,
 838     llvm_type: Type,
 839     type_metadata: DIType,
 840     offset: MemberOffset,
 841     flags: DIFlags,
 842 }
 843
 844 // A factory for MemberDescriptions. It produces a list of member descriptions
 845 // for some record-like type. MemberDescriptionFactories are used to defer the
 846 // creation of type member descriptions in order to break cycles arising from
 847 // recursive type definitions.
 848 enum MemberDescriptionFactory<'tcx> {
 849     StructMDF(StructMemberDescriptionFactory<'tcx>),
 850     TupleMDF(TupleMemberDescriptionFactory<'tcx>),
 851     EnumMDF(EnumMemberDescriptionFactory<'tcx>),
 852     UnionMDF(UnionMemberDescriptionFactory<'tcx>),
 853     VariantMDF(VariantMemberDescriptionFactory<'tcx>)
 854 }
 855
 856 impl<'tcx> MemberDescriptionFactory<'tcx> {
 857     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 858                                       -> Vec<MemberDescription> {
 859         match *self {
 860             StructMDF(ref this) => {
 861                 this.create_member_descriptions(cx)
 862             }
 863             TupleMDF(ref this) => {
 864                 this.create_member_descriptions(cx)
 865             }
 866             EnumMDF(ref this) => {
 867                 this.create_member_descriptions(cx)
 868             }
 869             UnionMDF(ref this) => {
 870                 this.create_member_descriptions(cx)
 871             }
 872             VariantMDF(ref this) => {
 873                 this.create_member_descriptions(cx)
 874             }
 875         }
 876     }
 877 }
 878
 879 //=-----------------------------------------------------------------------------
 880 // Structs
 881 //=-----------------------------------------------------------------------------
 882
 883 // Creates MemberDescriptions for the fields of a struct
 884 struct StructMemberDescriptionFactory<'tcx> {
 885     ty: Ty<'tcx>,
 886     variant: &'tcx ty::VariantDef,
 887     substs: &'tcx Substs<'tcx>,
 888     span: Span,
 889 }
 890
 891 impl<'tcx> StructMemberDescriptionFactory<'tcx> {
 892     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 893                                       -> Vec<MemberDescription> {
 894         let layout = cx.layout_of(self.ty);
 895
 896         let tmp;
 897         let offsets = match *layout {
 898             layout::Univariant { ref variant, .. } => &variant.offsets,
 899             layout::Vector { element, count } => {
 900                 let element_size = element.size(&cx.tcx().data_layout).bytes();
 901                 tmp = (0..count).
 902                   map(|i| layout::Size::from_bytes(i*element_size))
 903                   .collect::<Vec<layout::Size>>();
 904                 &tmp
 905             }
 906             _ => bug!("{} is not a struct", self.ty)
 907         };
 908
 909         self.variant.fields.iter().enumerate().map(|(i, f)| {
 910             let name = if self.variant.ctor_kind == CtorKind::Fn {
 911                 format!("__{}", i)
 912             } else {
 913                 f.name.to_string()
 914             };
 915             let fty = monomorphize::field_ty(cx.tcx(), self.substs, f);
 916
 917             let offset = FixedMemberOffset { bytes: offsets[i].bytes() as usize};
 918
 919             MemberDescription {
 920                 name: name,
 921                 llvm_type: type_of::in_memory_type_of(cx, fty),
 922                 type_metadata: type_metadata(cx, fty, self.span),
 923                 offset: offset,
 924                 flags: DIFlags::FlagZero,
 925             }
 926         }).collect()
 927     }
 928 }
 929
 930
 931 fn prepare_struct_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 932                                      struct_type: Ty<'tcx>,
 933                                      unique_type_id: UniqueTypeId,
 934                                      span: Span)
 935                                      -> RecursiveTypeDescription<'tcx> {
 936     let struct_name = compute_debuginfo_type_name(cx, struct_type, false);
 937     let struct_llvm_type = type_of::in_memory_type_of(cx, struct_type);
 938
 939     let (struct_def_id, variant, substs) = match struct_type.sty {
 940         ty::TyAdt(def, substs) => (def.did, def.struct_variant(), substs),
 941         _ => bug!("prepare_struct_metadata on a non-ADT")
 942     };
 943
 944     let (containing_scope, _) = get_namespace_and_span_for_item(cx, struct_def_id);
 945
 946     let struct_metadata_stub = create_struct_stub(cx,
 947                                                   struct_llvm_type,
 948                                                   &struct_name,
 949                                                   unique_type_id,
 950                                                   containing_scope);
 951
 952     create_and_register_recursive_type_forward_declaration(
 953         cx,
 954         struct_type,
 955         unique_type_id,
 956         struct_metadata_stub,
 957         struct_llvm_type,
 958         StructMDF(StructMemberDescriptionFactory {
 959             ty: struct_type,
 960             variant: variant,
 961             substs: substs,
 962             span: span,
 963         })
 964     )
 965 }
 966
 967 //=-----------------------------------------------------------------------------
 968 // Tuples
 969 //=-----------------------------------------------------------------------------
 970
 971 // Creates MemberDescriptions for the fields of a tuple
 972 struct TupleMemberDescriptionFactory<'tcx> {
 973     ty: Ty<'tcx>,
 974     component_types: Vec<Ty<'tcx>>,
 975     span: Span,
 976 }
 977
 978 impl<'tcx> TupleMemberDescriptionFactory<'tcx> {
 979     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 980                                       -> Vec<MemberDescription> {
 981         let layout = cx.layout_of(self.ty);
 982         let offsets = if let layout::Univariant { ref variant, .. } = *layout {
 983             &variant.offsets
 984         } else {
 985             bug!("{} is not a tuple", self.ty);
 986         };
 987
 988         self.component_types
 989             .iter()
 990             .enumerate()
 991             .map(|(i, &component_type)| {
 992             MemberDescription {
 993                 name: format!("__{}", i),
 994                 llvm_type: type_of::type_of(cx, component_type),
 995                 type_metadata: type_metadata(cx, component_type, self.span),
 996                 offset: FixedMemberOffset { bytes: offsets[i].bytes() as usize },
 997                 flags: DIFlags::FlagZero,
 998             }
 999         }).collect()
1000     }
1001 }
1002
1003 fn prepare_tuple_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1004                                     tuple_type: Ty<'tcx>,
1005                                     component_types: &[Ty<'tcx>],
1006                                     unique_type_id: UniqueTypeId,
1007                                     span: Span)
1008                                     -> RecursiveTypeDescription<'tcx> {
1009     let tuple_name = compute_debuginfo_type_name(cx, tuple_type, false);
1010     let tuple_llvm_type = type_of::type_of(cx, tuple_type);
1011
1012     create_and_register_recursive_type_forward_declaration(
1013         cx,
1014         tuple_type,
1015         unique_type_id,
1016         create_struct_stub(cx,
1017                            tuple_llvm_type,
1018                            &tuple_name[..],
1019                            unique_type_id,
1020                            NO_SCOPE_METADATA),
1021         tuple_llvm_type,
1022         TupleMDF(TupleMemberDescriptionFactory {
1023             ty: tuple_type,
1024             component_types: component_types.to_vec(),
1025             span: span,
1026         })
1027     )
1028 }
1029
1030 //=-----------------------------------------------------------------------------
1031 // Unions
1032 //=-----------------------------------------------------------------------------
1033
1034 struct UnionMemberDescriptionFactory<'tcx> {
1035     variant: &'tcx ty::VariantDef,
1036     substs: &'tcx Substs<'tcx>,
1037     span: Span,
1038 }
1039
1040 impl<'tcx> UnionMemberDescriptionFactory<'tcx> {
1041     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1042                                       -> Vec<MemberDescription> {
1043         self.variant.fields.iter().map(|field| {
1044             let fty = monomorphize::field_ty(cx.tcx(), self.substs, field);
1045             MemberDescription {
1046                 name: field.name.to_string(),
1047                 llvm_type: type_of::type_of(cx, fty),
1048                 type_metadata: type_metadata(cx, fty, self.span),
1049                 offset: FixedMemberOffset { bytes: 0 },
1050                 flags: DIFlags::FlagZero,
1051             }
1052         }).collect()
1053     }
1054 }
1055
1056 fn prepare_union_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1057                                     union_type: Ty<'tcx>,
1058                                     unique_type_id: UniqueTypeId,
1059                                     span: Span)
1060                                     -> RecursiveTypeDescription<'tcx> {
1061     let union_name = compute_debuginfo_type_name(cx, union_type, false);
1062     let union_llvm_type = type_of::in_memory_type_of(cx, union_type);
1063
1064     let (union_def_id, variant, substs) = match union_type.sty {
1065         ty::TyAdt(def, substs) => (def.did, def.struct_variant(), substs),
1066         _ => bug!("prepare_union_metadata on a non-ADT")
1067     };
1068
1069     let (containing_scope, _) = get_namespace_and_span_for_item(cx, union_def_id);
1070
1071     let union_metadata_stub = create_union_stub(cx,
1072                                                 union_llvm_type,
1073                                                 &union_name,
1074                                                 unique_type_id,
1075                                                 containing_scope);
1076
1077     create_and_register_recursive_type_forward_declaration(
1078         cx,
1079         union_type,
1080         unique_type_id,
1081         union_metadata_stub,
1082         union_llvm_type,
1083         UnionMDF(UnionMemberDescriptionFactory {
1084             variant: variant,
1085             substs: substs,
1086             span: span,
1087         })
1088     )
1089 }
1090
1091 //=-----------------------------------------------------------------------------
1092 // Enums
1093 //=-----------------------------------------------------------------------------
1094
1095 // Describes the members of an enum value: An enum is described as a union of
1096 // structs in DWARF. This MemberDescriptionFactory provides the description for
1097 // the members of this union; so for every variant of the given enum, this
1098 // factory will produce one MemberDescription (all with no name and a fixed
1099 // offset of zero bytes).
1100 struct EnumMemberDescriptionFactory<'tcx> {
1101     enum_type: Ty<'tcx>,
1102     type_rep: &'tcx layout::Layout,
1103     discriminant_type_metadata: Option<DIType>,
1104     containing_scope: DIScope,
1105     file_metadata: DIFile,
1106     span: Span,
1107 }
1108
1109 impl<'tcx> EnumMemberDescriptionFactory<'tcx> {
1110     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1111                                       -> Vec<MemberDescription> {
1112         let adt = &self.enum_type.ty_adt_def().unwrap();
1113         let substs = match self.enum_type.sty {
1114             ty::TyAdt(def, ref s) if def.adt_kind() == AdtKind::Enum => s,
1115             _ => bug!("{} is not an enum", self.enum_type)
1116         };
1117         match *self.type_rep {
1118             layout::General { ref variants, .. } => {
1119                 let discriminant_info = RegularDiscriminant(self.discriminant_type_metadata
1120                     .expect(""));
1121                 variants
1122                     .iter()
1123                     .enumerate()
1124                     .map(|(i, struct_def)| {
1125                         let (variant_type_metadata,
1126                              variant_llvm_type,
1127                              member_desc_factory) =
1128                             describe_enum_variant(cx,
1129                                                   self.enum_type,
1130                                                   struct_def,
1131                                                   &adt.variants[i],
1132                                                   discriminant_info,
1133                                                   self.containing_scope,
1134                                                   self.span);
1135
1136                         let member_descriptions = member_desc_factory
1137                             .create_member_descriptions(cx);
1138
1139                         set_members_of_composite_type(cx,
1140                                                       variant_type_metadata,
1141                                                       variant_llvm_type,
1142                                                       &member_descriptions);
1143                         MemberDescription {
1144                             name: "".to_string(),
1145                             llvm_type: variant_llvm_type,
1146                             type_metadata: variant_type_metadata,
1147                             offset: FixedMemberOffset { bytes: 0 },
1148                             flags: DIFlags::FlagZero
1149                         }
1150                     }).collect()
1151             },
1152             layout::Univariant{ ref variant, .. } => {
1153                 assert!(adt.variants.len() <= 1);
1154
1155                 if adt.variants.is_empty() {
1156                     vec![]
1157                 } else {
1158                     let (variant_type_metadata,
1159                          variant_llvm_type,
1160                          member_description_factory) =
1161                         describe_enum_variant(cx,
1162                                               self.enum_type,
1163                                               variant,
1164                                               &adt.variants[0],
1165                                               NoDiscriminant,
1166                                               self.containing_scope,
1167                                               self.span);
1168
1169                     let member_descriptions =
1170                         member_description_factory.create_member_descriptions(cx);
1171
1172                     set_members_of_composite_type(cx,
1173                                                   variant_type_metadata,
1174                                                   variant_llvm_type,
1175                                                   &member_descriptions[..]);
1176                     vec![
1177                         MemberDescription {
1178                             name: "".to_string(),
1179                             llvm_type: variant_llvm_type,
1180                             type_metadata: variant_type_metadata,
1181                             offset: FixedMemberOffset { bytes: 0 },
1182                             flags: DIFlags::FlagZero
1183                         }
1184                     ]
1185                 }
1186             }
1187             layout::RawNullablePointer { nndiscr: non_null_variant_index, .. } => {
1188                 // As far as debuginfo is concerned, the pointer this enum
1189                 // represents is still wrapped in a struct. This is to make the
1190                 // DWARF representation of enums uniform.
1191
1192                 // First create a description of the artificial wrapper struct:
1193                 let non_null_variant = &adt.variants[non_null_variant_index as usize];
1194                 let non_null_variant_name = non_null_variant.name.as_str();
1195
1196                 // The llvm type and metadata of the pointer
1197                 let nnty = monomorphize::field_ty(cx.tcx(), &substs, &non_null_variant.fields[0] );
1198                 let non_null_llvm_type = type_of::type_of(cx, nnty);
1199                 let non_null_type_metadata = type_metadata(cx, nnty, self.span);
1200
1201                 // The type of the artificial struct wrapping the pointer
1202                 let artificial_struct_llvm_type = Type::struct_(cx,
1203                                                                 &[non_null_llvm_type],
1204                                                                 false);
1205
1206                 // For the metadata of the wrapper struct, we need to create a
1207                 // MemberDescription of the struct's single field.
1208                 let sole_struct_member_description = MemberDescription {
1209                     name: match non_null_variant.ctor_kind {
1210                         CtorKind::Fn => "__0".to_string(),
1211                         CtorKind::Fictive => {
1212                             non_null_variant.fields[0].name.to_string()
1213                         }
1214                         CtorKind::Const => bug!()
1215                     },
1216                     llvm_type: non_null_llvm_type,
1217                     type_metadata: non_null_type_metadata,
1218                     offset: FixedMemberOffset { bytes: 0 },
1219                     flags: DIFlags::FlagZero
1220                 };
1221
1222                 let unique_type_id = debug_context(cx).type_map
1223                                                       .borrow_mut()
1224                                                       .get_unique_type_id_of_enum_variant(
1225                                                           cx,
1226                                                           self.enum_type,
1227                                                           &non_null_variant_name);
1228
1229                 // Now we can create the metadata of the artificial struct
1230                 let artificial_struct_metadata =
1231                     composite_type_metadata(cx,
1232                                             artificial_struct_llvm_type,
1233                                             &non_null_variant_name,
1234                                             unique_type_id,
1235                                             &[sole_struct_member_description],
1236                                             self.containing_scope,
1237                                             self.file_metadata,
1238                                             syntax_pos::DUMMY_SP);
1239
1240                 // Encode the information about the null variant in the union
1241                 // member's name.
1242                 let null_variant_index = (1 - non_null_variant_index) as usize;
1243                 let null_variant_name = adt.variants[null_variant_index].name;
1244                 let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
1245                                                 0,
1246                                                 null_variant_name);
1247
1248                 // Finally create the (singleton) list of descriptions of union
1249                 // members.
1250                 vec![
1251                     MemberDescription {
1252                         name: union_member_name,
1253                         llvm_type: artificial_struct_llvm_type,
1254                         type_metadata: artificial_struct_metadata,
1255                         offset: FixedMemberOffset { bytes: 0 },
1256                         flags: DIFlags::FlagZero
1257                     }
1258                 ]
1259             },
1260             layout::StructWrappedNullablePointer { nonnull: ref struct_def,
1261                                                 nndiscr,
1262                                                 ref discrfield_source, ..} => {
1263                 // Create a description of the non-null variant
1264                 let (variant_type_metadata, variant_llvm_type, member_description_factory) =
1265                     describe_enum_variant(cx,
1266                                           self.enum_type,
1267                                           struct_def,
1268                                           &adt.variants[nndiscr as usize],
1269                                           OptimizedDiscriminant,
1270                                           self.containing_scope,
1271                                           self.span);
1272
1273                 let variant_member_descriptions =
1274                     member_description_factory.create_member_descriptions(cx);
1275
1276                 set_members_of_composite_type(cx,
1277                                               variant_type_metadata,
1278                                               variant_llvm_type,
1279                                               &variant_member_descriptions[..]);
1280
1281                 // Encode the information about the null variant in the union
1282                 // member's name.
1283                 let null_variant_index = (1 - nndiscr) as usize;
1284                 let null_variant_name = adt.variants[null_variant_index].name;
1285                 let discrfield_source = discrfield_source.iter()
1286                                            .skip(1)
1287                                            .map(|x| x.to_string())
1288                                            .collect::<Vec<_>>().join("$");
1289                 let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
1290                                                 discrfield_source,
1291                                                 null_variant_name);
1292
1293                 // Create the (singleton) list of descriptions of union members.
1294                 vec![
1295                     MemberDescription {
1296                         name: union_member_name,
1297                         llvm_type: variant_llvm_type,
1298                         type_metadata: variant_type_metadata,
1299                         offset: FixedMemberOffset { bytes: 0 },
1300                         flags: DIFlags::FlagZero
1301                     }
1302                 ]
1303             },
1304             layout::CEnum { .. } => span_bug!(self.span, "This should be unreachable."),
1305             ref l @ _ => bug!("Not an enum layout: {:#?}", l)
1306         }
1307     }
1308 }
1309
1310 // Creates MemberDescriptions for the fields of a single enum variant.
1311 struct VariantMemberDescriptionFactory<'tcx> {
1312     // Cloned from the layout::Struct describing the variant.
1313     offsets: &'tcx [layout::Size],
1314     args: Vec<(String, Ty<'tcx>)>,
1315     discriminant_type_metadata: Option<DIType>,
1316     span: Span,
1317 }
1318
1319 impl<'tcx> VariantMemberDescriptionFactory<'tcx> {
1320     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1321                                       -> Vec<MemberDescription> {
1322         self.args.iter().enumerate().map(|(i, &(ref name, ty))| {
1323             MemberDescription {
1324                 name: name.to_string(),
1325                 llvm_type: type_of::type_of(cx, ty),
1326                 type_metadata: match self.discriminant_type_metadata {
1327                     Some(metadata) if i == 0 => metadata,
1328                     _ => type_metadata(cx, ty, self.span)
1329                 },
1330                 offset: FixedMemberOffset { bytes: self.offsets[i].bytes() as usize },
1331                 flags: DIFlags::FlagZero
1332             }
1333         }).collect()
1334     }
1335 }
1336
1337 #[derive(Copy, Clone)]
1338 enum EnumDiscriminantInfo {
1339     RegularDiscriminant(DIType),
1340     OptimizedDiscriminant,
1341     NoDiscriminant
1342 }
1343
1344 // Returns a tuple of (1) type_metadata_stub of the variant, (2) the llvm_type
1345 // of the variant, and (3) a MemberDescriptionFactory for producing the
1346 // descriptions of the fields of the variant. This is a rudimentary version of a
1347 // full RecursiveTypeDescription.
1348 fn describe_enum_variant<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1349                                    enum_type: Ty<'tcx>,
1350                                    struct_def: &'tcx layout::Struct,
1351                                    variant: &'tcx ty::VariantDef,
1352                                    discriminant_info: EnumDiscriminantInfo,
1353                                    containing_scope: DIScope,
1354                                    span: Span)
1355                                    -> (DICompositeType, Type, MemberDescriptionFactory<'tcx>) {
1356     let substs = match enum_type.sty {
1357         ty::TyAdt(def, s) if def.adt_kind() == AdtKind::Enum => s,
1358         ref t @ _ => bug!("{:#?} is not an enum", t)
1359     };
1360
1361     let maybe_discr_and_signed: Option<(layout::Integer, bool)> = match *cx.layout_of(enum_type) {
1362         layout::CEnum {discr, ..} => Some((discr, true)),
1363         layout::General{discr, ..} => Some((discr, false)),
1364         layout::Univariant { .. }
1365         | layout::RawNullablePointer { .. }
1366         | layout::StructWrappedNullablePointer { .. } => None,
1367         ref l @ _ => bug!("This should be unreachable. Type is {:#?} layout is {:#?}", enum_type, l)
1368     };
1369
1370     let mut field_tys = variant.fields.iter().map(|f| {
1371         monomorphize::field_ty(cx.tcx(), &substs, f)
1372     }).collect::<Vec<_>>();
1373
1374     if let Some((discr, signed)) = maybe_discr_and_signed {
1375         field_tys.insert(0, discr.to_ty(&cx.tcx(), signed));
1376     }
1377
1378
1379     let variant_llvm_type =
1380         Type::struct_(cx, &field_tys
1381                                     .iter()
1382                                     .map(|t| type_of::type_of(cx, t))
1383                                     .collect::<Vec<_>>()
1384                                     ,
1385                       struct_def.packed);
1386     // Could do some consistency checks here: size, align, field count, discr type
1387
1388     let variant_name = variant.name.as_str();
1389     let unique_type_id = debug_context(cx).type_map
1390                                           .borrow_mut()
1391                                           .get_unique_type_id_of_enum_variant(
1392                                               cx,
1393                                               enum_type,
1394                                               &variant_name);
1395
1396     let metadata_stub = create_struct_stub(cx,
1397                                            variant_llvm_type,
1398                                            &variant_name,
1399                                            unique_type_id,
1400                                            containing_scope);
1401
1402     // Get the argument names from the enum variant info
1403     let mut arg_names: Vec<_> = match variant.ctor_kind {
1404         CtorKind::Const => vec![],
1405         CtorKind::Fn => {
1406             variant.fields
1407                    .iter()
1408                    .enumerate()
1409                    .map(|(i, _)| format!("__{}", i))
1410                    .collect()
1411         }
1412         CtorKind::Fictive => {
1413             variant.fields
1414                    .iter()
1415                    .map(|f| f.name.to_string())
1416                    .collect()
1417         }
1418     };
1419
1420     // If this is not a univariant enum, there is also the discriminant field.
1421     match discriminant_info {
1422         RegularDiscriminant(_) => arg_names.insert(0, "RUST$ENUM$DISR".to_string()),
1423         _ => { /* do nothing */ }
1424     };
1425
1426     // Build an array of (field name, field type) pairs to be captured in the factory closure.
1427     let args: Vec<(String, Ty)> = arg_names.iter()
1428         .zip(field_tys.iter())
1429         .map(|(s, &t)| (s.to_string(), t))
1430         .collect();
1431
1432     let member_description_factory =
1433         VariantMDF(VariantMemberDescriptionFactory {
1434             offsets: &struct_def.offsets[..],
1435             args: args,
1436             discriminant_type_metadata: match discriminant_info {
1437                 RegularDiscriminant(discriminant_type_metadata) => {
1438                     Some(discriminant_type_metadata)
1439                 }
1440                 _ => None
1441             },
1442             span: span,
1443         });
1444
1445     (metadata_stub, variant_llvm_type, member_description_factory)
1446 }
1447
1448 fn prepare_enum_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1449                                    enum_type: Ty<'tcx>,
1450                                    enum_def_id: DefId,
1451                                    unique_type_id: UniqueTypeId,
1452                                    span: Span)
1453                                    -> RecursiveTypeDescription<'tcx> {
1454     let enum_name = compute_debuginfo_type_name(cx, enum_type, false);
1455
1456     let (containing_scope, _) = get_namespace_and_span_for_item(cx, enum_def_id);
1457     // FIXME: This should emit actual file metadata for the enum, but we
1458     // currently can't get the necessary information when it comes to types
1459     // imported from other crates. Formerly we violated the ODR when performing
1460     // LTO because we emitted debuginfo for the same type with varying file
1461     // metadata, so as a workaround we pretend that the type comes from
1462     // <unknown>
1463     let file_metadata = unknown_file_metadata(cx);
1464
1465     let variants = &enum_type.ty_adt_def().unwrap().variants;
1466     let enumerators_metadata: Vec<DIDescriptor> = variants
1467         .iter()
1468         .map(|v| {
1469             let token = v.name.as_str();
1470             let name = CString::new(token.as_bytes()).unwrap();
1471             unsafe {
1472                 llvm::LLVMRustDIBuilderCreateEnumerator(
1473                     DIB(cx),
1474                     name.as_ptr(),
1475                     // FIXME: what if enumeration has i128 discriminant?
1476                     v.disr_val.to_u128_unchecked() as u64)
1477             }
1478         })
1479         .collect();
1480
1481     let discriminant_type_metadata = |inttype: layout::Integer, signed: bool| {
1482         let disr_type_key = (enum_def_id, inttype);
1483         let cached_discriminant_type_metadata = debug_context(cx).created_enum_disr_types
1484                                                                  .borrow()
1485                                                                  .get(&disr_type_key).cloned();
1486         match cached_discriminant_type_metadata {
1487             Some(discriminant_type_metadata) => discriminant_type_metadata,
1488             None => {
1489                 let discriminant_llvm_type = Type::from_integer(cx, inttype);
1490                 let (discriminant_size, discriminant_align) =
1491                     size_and_align_of(cx, discriminant_llvm_type);
1492                 let discriminant_base_type_metadata =
1493                     type_metadata(cx,
1494                                   inttype.to_ty(&cx.tcx(), signed),
1495                                   syntax_pos::DUMMY_SP);
1496                 let discriminant_name = get_enum_discriminant_name(cx, enum_def_id);
1497
1498                 let name = CString::new(discriminant_name.as_bytes()).unwrap();
1499                 let discriminant_type_metadata = unsafe {
1500                     llvm::LLVMRustDIBuilderCreateEnumerationType(
1501                         DIB(cx),
1502                         containing_scope,
1503                         name.as_ptr(),
1504                         file_metadata,
1505                         UNKNOWN_LINE_NUMBER,
1506                         bytes_to_bits(discriminant_size),
1507                         bytes_to_bits(discriminant_align),
1508                         create_DIArray(DIB(cx), &enumerators_metadata),
1509                         discriminant_base_type_metadata)
1510                 };
1511
1512                 debug_context(cx).created_enum_disr_types
1513                                  .borrow_mut()
1514                                  .insert(disr_type_key, discriminant_type_metadata);
1515
1516                 discriminant_type_metadata
1517             }
1518         }
1519     };
1520
1521     let type_rep = cx.layout_of(enum_type);
1522
1523     let discriminant_type_metadata = match *type_rep {
1524         layout::CEnum { discr, signed, .. } => {
1525             return FinalMetadata(discriminant_type_metadata(discr, signed))
1526         },
1527         layout::RawNullablePointer { .. }           |
1528         layout::StructWrappedNullablePointer { .. } |
1529         layout::Univariant { .. }                      => None,
1530         layout::General { discr, .. } => Some(discriminant_type_metadata(discr, false)),
1531         ref l @ _ => bug!("Not an enum layout: {:#?}", l)
1532     };
1533
1534     let enum_llvm_type = type_of::type_of(cx, enum_type);
1535     let (enum_type_size, enum_type_align) = size_and_align_of(cx, enum_llvm_type);
1536
1537     let enum_name = CString::new(enum_name).unwrap();
1538     let unique_type_id_str = CString::new(
1539         debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
1540     ).unwrap();
1541     let enum_metadata = unsafe {
1542         llvm::LLVMRustDIBuilderCreateUnionType(
1543         DIB(cx),
1544         containing_scope,
1545         enum_name.as_ptr(),
1546         file_metadata,
1547         UNKNOWN_LINE_NUMBER,
1548         bytes_to_bits(enum_type_size),
1549         bytes_to_bits(enum_type_align),
1550         DIFlags::FlagZero,
1551         ptr::null_mut(),
1552         0, // RuntimeLang
1553         unique_type_id_str.as_ptr())
1554     };
1555
1556     return create_and_register_recursive_type_forward_declaration(
1557         cx,
1558         enum_type,
1559         unique_type_id,
1560         enum_metadata,
1561         enum_llvm_type,
1562         EnumMDF(EnumMemberDescriptionFactory {
1563             enum_type: enum_type,
1564             type_rep: type_rep,
1565             discriminant_type_metadata: discriminant_type_metadata,
1566             containing_scope: containing_scope,
1567             file_metadata: file_metadata,
1568             span: span,
1569         }),
1570     );
1571
1572     fn get_enum_discriminant_name(cx: &CrateContext,
1573                                   def_id: DefId)
1574                                   -> InternedString {
1575         cx.tcx().item_name(def_id).as_str()
1576     }
1577 }
1578
1579 /// Creates debug information for a composite type, that is, anything that
1580 /// results in a LLVM struct.
1581 ///
1582 /// Examples of Rust types to use this are: structs, tuples, boxes, vecs, and enums.
1583 fn composite_type_metadata(cx: &CrateContext,
1584                            composite_llvm_type: Type,
1585                            composite_type_name: &str,
1586                            composite_type_unique_id: UniqueTypeId,
1587                            member_descriptions: &[MemberDescription],
1588                            containing_scope: DIScope,
1589
1590                            // Ignore source location information as long as it
1591                            // can't be reconstructed for non-local crates.
1592                            _file_metadata: DIFile,
1593                            _definition_span: Span)
1594                            -> DICompositeType {
1595     // Create the (empty) struct metadata node ...
1596     let composite_type_metadata = create_struct_stub(cx,
1597                                                      composite_llvm_type,
1598                                                      composite_type_name,
1599                                                      composite_type_unique_id,
1600                                                      containing_scope);
1601     // ... and immediately create and add the member descriptions.
1602     set_members_of_composite_type(cx,
1603                                   composite_type_metadata,
1604                                   composite_llvm_type,
1605                                   member_descriptions);
1606
1607     return composite_type_metadata;
1608 }
1609
1610 fn set_members_of_composite_type(cx: &CrateContext,
1611                                  composite_type_metadata: DICompositeType,
1612                                  composite_llvm_type: Type,
1613                                  member_descriptions: &[MemberDescription]) {
1614     // In some rare cases LLVM metadata uniquing would lead to an existing type
1615     // description being used instead of a new one created in
1616     // create_struct_stub. This would cause a hard to trace assertion in
1617     // DICompositeType::SetTypeArray(). The following check makes sure that we
1618     // get a better error message if this should happen again due to some
1619     // regression.
1620     {
1621         let mut composite_types_completed =
1622             debug_context(cx).composite_types_completed.borrow_mut();
1623         if composite_types_completed.contains(&composite_type_metadata) {
1624             bug!("debuginfo::set_members_of_composite_type() - \
1625                   Already completed forward declaration re-encountered.");
1626         } else {
1627             composite_types_completed.insert(composite_type_metadata);
1628         }
1629     }
1630
1631     let member_metadata: Vec<DIDescriptor> = member_descriptions
1632         .iter()
1633         .enumerate()
1634         .map(|(i, member_description)| {
1635             let (member_size, member_align) = size_and_align_of(cx, member_description.llvm_type);
1636             let member_offset = match member_description.offset {
1637                 FixedMemberOffset { bytes } => bytes as u64,
1638                 ComputedMemberOffset => machine::llelement_offset(cx, composite_llvm_type, i)
1639             };
1640
1641             let member_name = member_description.name.as_bytes();
1642             let member_name = CString::new(member_name).unwrap();
1643             unsafe {
1644                 llvm::LLVMRustDIBuilderCreateMemberType(
1645                     DIB(cx),
1646                     composite_type_metadata,
1647                     member_name.as_ptr(),
1648                     unknown_file_metadata(cx),
1649                     UNKNOWN_LINE_NUMBER,
1650                     bytes_to_bits(member_size),
1651                     bytes_to_bits(member_align),
1652                     bytes_to_bits(member_offset),
1653                     member_description.flags,
1654                     member_description.type_metadata)
1655             }
1656         })
1657         .collect();
1658
1659     unsafe {
1660         let type_array = create_DIArray(DIB(cx), &member_metadata[..]);
1661         llvm::LLVMRustDICompositeTypeSetTypeArray(
1662             DIB(cx), composite_type_metadata, type_array);
1663     }
1664 }
1665
1666 // A convenience wrapper around LLVMRustDIBuilderCreateStructType(). Does not do
1667 // any caching, does not add any fields to the struct. This can be done later
1668 // with set_members_of_composite_type().
1669 fn create_struct_stub(cx: &CrateContext,
1670                       struct_llvm_type: Type,
1671                       struct_type_name: &str,
1672                       unique_type_id: UniqueTypeId,
1673                       containing_scope: DIScope)
1674                    -> DICompositeType {
1675     let (struct_size, struct_align) = size_and_align_of(cx, struct_llvm_type);
1676
1677     let name = CString::new(struct_type_name).unwrap();
1678     let unique_type_id = CString::new(
1679         debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
1680     ).unwrap();
1681     let metadata_stub = unsafe {
1682         // LLVMRustDIBuilderCreateStructType() wants an empty array. A null
1683         // pointer will lead to hard to trace and debug LLVM assertions
1684         // later on in llvm/lib/IR/Value.cpp.
1685         let empty_array = create_DIArray(DIB(cx), &[]);
1686
1687         llvm::LLVMRustDIBuilderCreateStructType(
1688             DIB(cx),
1689             containing_scope,
1690             name.as_ptr(),
1691             unknown_file_metadata(cx),
1692             UNKNOWN_LINE_NUMBER,
1693             bytes_to_bits(struct_size),
1694             bytes_to_bits(struct_align),
1695             DIFlags::FlagZero,
1696             ptr::null_mut(),
1697             empty_array,
1698             0,
1699             ptr::null_mut(),
1700             unique_type_id.as_ptr())
1701     };
1702
1703     return metadata_stub;
1704 }
1705
1706 fn create_union_stub(cx: &CrateContext,
1707                      union_llvm_type: Type,
1708                      union_type_name: &str,
1709                      unique_type_id: UniqueTypeId,
1710                      containing_scope: DIScope)
1711                    -> DICompositeType {
1712     let (union_size, union_align) = size_and_align_of(cx, union_llvm_type);
1713
1714     let name = CString::new(union_type_name).unwrap();
1715     let unique_type_id = CString::new(
1716         debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
1717     ).unwrap();
1718     let metadata_stub = unsafe {
1719         // LLVMRustDIBuilderCreateUnionType() wants an empty array. A null
1720         // pointer will lead to hard to trace and debug LLVM assertions
1721         // later on in llvm/lib/IR/Value.cpp.
1722         let empty_array = create_DIArray(DIB(cx), &[]);
1723
1724         llvm::LLVMRustDIBuilderCreateUnionType(
1725             DIB(cx),
1726             containing_scope,
1727             name.as_ptr(),
1728             unknown_file_metadata(cx),
1729             UNKNOWN_LINE_NUMBER,
1730             bytes_to_bits(union_size),
1731             bytes_to_bits(union_align),
1732             DIFlags::FlagZero,
1733             empty_array,
1734             0, // RuntimeLang
1735             unique_type_id.as_ptr())
1736     };
1737
1738     return metadata_stub;
1739 }
1740
1741 /// Creates debug information for the given global variable.
1742 ///
1743 /// Adds the created metadata nodes directly to the crate's IR.
1744 pub fn create_global_var_metadata(cx: &CrateContext,
1745                                   node_id: ast::NodeId,
1746                                   global: ValueRef) {
1747     if cx.dbg_cx().is_none() {
1748         return;
1749     }
1750
1751     let tcx = cx.tcx();
1752
1753     let node_def_id = tcx.hir.local_def_id(node_id);
1754     let (var_scope, span) = get_namespace_and_span_for_item(cx, node_def_id);
1755
1756     let (file_metadata, line_number) = if span != syntax_pos::DUMMY_SP {
1757         let loc = span_start(cx, span);
1758         (file_metadata(cx, &loc.file.name, &loc.file.abs_path), loc.line as c_uint)
1759     } else {
1760         (unknown_file_metadata(cx), UNKNOWN_LINE_NUMBER)
1761     };
1762
1763     let is_local_to_unit = is_node_local_to_unit(cx, node_id);
1764     let variable_type = tcx.erase_regions(&tcx.item_type(node_def_id));
1765     let type_metadata = type_metadata(cx, variable_type, span);
1766     let var_name = tcx.item_name(node_def_id).to_string();
1767     let linkage_name = mangled_name_of_item(cx, node_def_id, "");
1768
1769     let var_name = CString::new(var_name).unwrap();
1770     let linkage_name = CString::new(linkage_name).unwrap();
1771
1772     let ty = cx.tcx().item_type(node_def_id);
1773     let global_align = type_of::align_of(cx, ty);
1774
1775     unsafe {
1776         llvm::LLVMRustDIBuilderCreateStaticVariable(DIB(cx),
1777                                                     var_scope,
1778                                                     var_name.as_ptr(),
1779                                                     linkage_name.as_ptr(),
1780                                                     file_metadata,
1781                                                     line_number,
1782                                                     type_metadata,
1783                                                     is_local_to_unit,
1784                                                     global,
1785                                                     ptr::null_mut(),
1786                                                     global_align as u64,
1787         );
1788     }
1789 }
1790
1791 // Creates an "extension" of an existing DIScope into another file.
1792 pub fn extend_scope_to_file(ccx: &CrateContext,
1793                             scope_metadata: DIScope,
1794                             file: &syntax_pos::FileMap)
1795                             -> DILexicalBlock {
1796     let file_metadata = file_metadata(ccx, &file.name, &file.abs_path);
1797     unsafe {
1798         llvm::LLVMRustDIBuilderCreateLexicalBlockFile(
1799             DIB(ccx),
1800             scope_metadata,
1801             file_metadata)
1802     }
1803 }