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, DICompositeType, DILexicalBlock};
  26
  27 use rustc::hir::def::CtorKind;
  28 use rustc::hir::def_id::DefId;
  29 use rustc::ty::fold::TypeVisitor;
  30 use rustc::ty::subst::Substs;
  31 use rustc::ty::util::TypeIdHasher;
  32 use rustc::hir;
  33 use rustc_data_structures::blake2b::Blake2bHasher;
  34 use {type_of, machine, monomorphize};
  35 use common::CrateContext;
  36 use type_::Type;
  37 use rustc::ty::{self, AdtKind, Ty, layout};
  38 use session::config;
  39 use util::nodemap::FnvHashMap;
  40 use util::common::path2cstr;
  41
  42 use libc::{c_uint, c_longlong};
  43 use std::ffi::CString;
  44 use std::fmt::Write;
  45 use std::path::Path;
  46 use std::ptr;
  47 use std::rc::Rc;
  48 use syntax::util::interner::Interner;
  49 use syntax::ast;
  50 use syntax::parse::token;
  51 use syntax_pos::{self, Span};
  52
  53
  54 // From DWARF 5.
  55 // See http://www.dwarfstd.org/ShowIssue.php?issue=140129.1
  56 const DW_LANG_RUST: c_uint = 0x1c;
  57 #[allow(non_upper_case_globals)]
  58 const DW_ATE_boolean: c_uint = 0x02;
  59 #[allow(non_upper_case_globals)]
  60 const DW_ATE_float: c_uint = 0x04;
  61 #[allow(non_upper_case_globals)]
  62 const DW_ATE_signed: c_uint = 0x05;
  63 #[allow(non_upper_case_globals)]
  64 const DW_ATE_unsigned: c_uint = 0x07;
  65 #[allow(non_upper_case_globals)]
  66 const DW_ATE_unsigned_char: c_uint = 0x08;
  67
  68 pub const UNKNOWN_LINE_NUMBER: c_uint = 0;
  69 pub const UNKNOWN_COLUMN_NUMBER: c_uint = 0;
  70
  71 // ptr::null() doesn't work :(
  72 pub const NO_SCOPE_METADATA: DIScope = (0 as DIScope);
  73
  74 const FLAGS_NONE: c_uint = 0;
  75
  76 #[derive(Copy, Debug, Hash, Eq, PartialEq, Clone)]
  77 pub struct UniqueTypeId(ast::Name);
  78
  79 // The TypeMap is where the CrateDebugContext holds the type metadata nodes
  80 // created so far. The metadata nodes are indexed by UniqueTypeId, and, for
  81 // faster lookup, also by Ty. The TypeMap is responsible for creating
  82 // UniqueTypeIds.
  83 pub struct TypeMap<'tcx> {
  84     // The UniqueTypeIds created so far
  85     unique_id_interner: Interner,
  86     // A map from UniqueTypeId to debuginfo metadata for that type. This is a 1:1 mapping.
  87     unique_id_to_metadata: FnvHashMap<UniqueTypeId, DIType>,
  88     // A map from types to debuginfo metadata. This is a N:1 mapping.
  89     type_to_metadata: FnvHashMap<Ty<'tcx>, DIType>,
  90     // A map from types to UniqueTypeId. This is a N:1 mapping.
  91     type_to_unique_id: FnvHashMap<Ty<'tcx>, UniqueTypeId>
  92 }
  93
  94 impl<'tcx> TypeMap<'tcx> {
  95     pub fn new() -> TypeMap<'tcx> {
  96         TypeMap {
  97             unique_id_interner: Interner::new(),
  98             type_to_metadata: FnvHashMap(),
  99             unique_id_to_metadata: FnvHashMap(),
 100             type_to_unique_id: FnvHashMap(),
 101         }
 102     }
 103
 104     // Adds a Ty to metadata mapping to the TypeMap. The method will fail if
 105     // the mapping already exists.
 106     fn register_type_with_metadata<'a>(&mut self,
 107                                        type_: Ty<'tcx>,
 108                                        metadata: DIType) {
 109         if self.type_to_metadata.insert(type_, metadata).is_some() {
 110             bug!("Type metadata for Ty '{}' is already in the TypeMap!", type_);
 111         }
 112     }
 113
 114     // Adds a UniqueTypeId to metadata mapping to the TypeMap. The method will
 115     // fail if the mapping already exists.
 116     fn register_unique_id_with_metadata(&mut self,
 117                                         unique_type_id: UniqueTypeId,
 118                                         metadata: DIType) {
 119         if self.unique_id_to_metadata.insert(unique_type_id, metadata).is_some() {
 120             let unique_type_id_str = self.get_unique_type_id_as_string(unique_type_id);
 121             bug!("Type metadata for unique id '{}' is already in the TypeMap!",
 122                  &unique_type_id_str[..]);
 123         }
 124     }
 125
 126     fn find_metadata_for_type(&self, type_: Ty<'tcx>) -> Option<DIType> {
 127         self.type_to_metadata.get(&type_).cloned()
 128     }
 129
 130     fn find_metadata_for_unique_id(&self, unique_type_id: UniqueTypeId) -> Option<DIType> {
 131         self.unique_id_to_metadata.get(&unique_type_id).cloned()
 132     }
 133
 134     // Get the string representation of a UniqueTypeId. This method will fail if
 135     // the id is unknown.
 136     fn get_unique_type_id_as_string(&self, unique_type_id: UniqueTypeId) -> Rc<str> {
 137         let UniqueTypeId(interner_key) = unique_type_id;
 138         self.unique_id_interner.get(interner_key)
 139     }
 140
 141     // Get the UniqueTypeId for the given type. If the UniqueTypeId for the given
 142     // type has been requested before, this is just a table lookup. Otherwise an
 143     // ID will be generated and stored for later lookup.
 144     fn get_unique_type_id_of_type<'a>(&mut self, cx: &CrateContext<'a, 'tcx>,
 145                                       type_: Ty<'tcx>) -> UniqueTypeId {
 146         // Let's see if we already have something in the cache
 147         match self.type_to_unique_id.get(&type_).cloned() {
 148             Some(unique_type_id) => return unique_type_id,
 149             None => { /* generate one */}
 150         };
 151
 152         // The hasher we are using to generate the UniqueTypeId. We want
 153         // something that provides more than the 64 bits of the DefaultHasher.
 154         const TYPE_ID_HASH_LENGTH: usize = 20;
 155
 156         let mut type_id_hasher = TypeIdHasher::new(cx.tcx(),
 157                                                    Blake2bHasher::new(TYPE_ID_HASH_LENGTH, &[]));
 158         type_id_hasher.visit_ty(type_);
 159         let mut hash_state = type_id_hasher.into_inner();
 160         let hash: &[u8] = hash_state.finalize();
 161         debug_assert!(hash.len() == TYPE_ID_HASH_LENGTH);
 162
 163         let mut unique_type_id = String::with_capacity(TYPE_ID_HASH_LENGTH * 2);
 164
 165         for byte in hash.into_iter() {
 166             write!(&mut unique_type_id, "{:x}", byte).unwrap();
 167         }
 168
 169         let key = self.unique_id_interner.intern(&unique_type_id);
 170         self.type_to_unique_id.insert(type_, UniqueTypeId(key));
 171
 172         return UniqueTypeId(key);
 173     }
 174
 175     // Get the UniqueTypeId for an enum variant. Enum variants are not really
 176     // types of their own, so they need special handling. We still need a
 177     // UniqueTypeId for them, since to debuginfo they *are* real types.
 178     fn get_unique_type_id_of_enum_variant<'a>(&mut self,
 179                                               cx: &CrateContext<'a, 'tcx>,
 180                                               enum_type: Ty<'tcx>,
 181                                               variant_name: &str)
 182                                               -> UniqueTypeId {
 183         let enum_type_id = self.get_unique_type_id_of_type(cx, enum_type);
 184         let enum_variant_type_id = format!("{}::{}",
 185                                            &self.get_unique_type_id_as_string(enum_type_id),
 186                                            variant_name);
 187         let interner_key = self.unique_id_interner.intern(&enum_variant_type_id);
 188         UniqueTypeId(interner_key)
 189     }
 190 }
 191
 192 // A description of some recursive type. It can either be already finished (as
 193 // with FinalMetadata) or it is not yet finished, but contains all information
 194 // needed to generate the missing parts of the description. See the
 195 // documentation section on Recursive Types at the top of this file for more
 196 // information.
 197 enum RecursiveTypeDescription<'tcx> {
 198     UnfinishedMetadata {
 199         unfinished_type: Ty<'tcx>,
 200         unique_type_id: UniqueTypeId,
 201         metadata_stub: DICompositeType,
 202         llvm_type: Type,
 203         member_description_factory: MemberDescriptionFactory<'tcx>,
 204     },
 205     FinalMetadata(DICompositeType)
 206 }
 207
 208 fn create_and_register_recursive_type_forward_declaration<'a, 'tcx>(
 209     cx: &CrateContext<'a, 'tcx>,
 210     unfinished_type: Ty<'tcx>,
 211     unique_type_id: UniqueTypeId,
 212     metadata_stub: DICompositeType,
 213     llvm_type: Type,
 214     member_description_factory: MemberDescriptionFactory<'tcx>)
 215  -> RecursiveTypeDescription<'tcx> {
 216
 217     // Insert the stub into the TypeMap in order to allow for recursive references
 218     let mut type_map = debug_context(cx).type_map.borrow_mut();
 219     type_map.register_unique_id_with_metadata(unique_type_id, metadata_stub);
 220     type_map.register_type_with_metadata(unfinished_type, metadata_stub);
 221
 222     UnfinishedMetadata {
 223         unfinished_type: unfinished_type,
 224         unique_type_id: unique_type_id,
 225         metadata_stub: metadata_stub,
 226         llvm_type: llvm_type,
 227         member_description_factory: member_description_factory,
 228     }
 229 }
 230
 231 impl<'tcx> RecursiveTypeDescription<'tcx> {
 232     // Finishes up the description of the type in question (mostly by providing
 233     // descriptions of the fields of the given type) and returns the final type
 234     // metadata.
 235     fn finalize<'a>(&self, cx: &CrateContext<'a, 'tcx>) -> MetadataCreationResult {
 236         match *self {
 237             FinalMetadata(metadata) => MetadataCreationResult::new(metadata, false),
 238             UnfinishedMetadata {
 239                 unfinished_type,
 240                 unique_type_id,
 241                 metadata_stub,
 242                 llvm_type,
 243                 ref member_description_factory,
 244                 ..
 245             } => {
 246                 // Make sure that we have a forward declaration of the type in
 247                 // the TypeMap so that recursive references are possible. This
 248                 // will always be the case if the RecursiveTypeDescription has
 249                 // been properly created through the
 250                 // create_and_register_recursive_type_forward_declaration()
 251                 // function.
 252                 {
 253                     let type_map = debug_context(cx).type_map.borrow();
 254                     if type_map.find_metadata_for_unique_id(unique_type_id).is_none() ||
 255                        type_map.find_metadata_for_type(unfinished_type).is_none() {
 256                         bug!("Forward declaration of potentially recursive type \
 257                               '{:?}' was not found in TypeMap!",
 258                              unfinished_type);
 259                     }
 260                 }
 261
 262                 // ... then create the member descriptions ...
 263                 let member_descriptions =
 264                     member_description_factory.create_member_descriptions(cx);
 265
 266                 // ... and attach them to the stub to complete it.
 267                 set_members_of_composite_type(cx,
 268                                               metadata_stub,
 269                                               llvm_type,
 270                                               &member_descriptions[..]);
 271                 return MetadataCreationResult::new(metadata_stub, true);
 272             }
 273         }
 274     }
 275 }
 276
 277 // Returns from the enclosing function if the type metadata with the given
 278 // unique id can be found in the type map
 279 macro_rules! return_if_metadata_created_in_meantime {
 280     ($cx: expr, $unique_type_id: expr) => (
 281         match debug_context($cx).type_map
 282                                 .borrow()
 283                                 .find_metadata_for_unique_id($unique_type_id) {
 284             Some(metadata) => return MetadataCreationResult::new(metadata, true),
 285             None => { /* proceed normally */ }
 286         }
 287     )
 288 }
 289
 290 fn fixed_vec_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 291                                 unique_type_id: UniqueTypeId,
 292                                 element_type: Ty<'tcx>,
 293                                 len: Option<u64>,
 294                                 span: Span)
 295                                 -> MetadataCreationResult {
 296     let element_type_metadata = type_metadata(cx, element_type, span);
 297
 298     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 299
 300     let element_llvm_type = type_of::type_of(cx, element_type);
 301     let (element_type_size, element_type_align) = size_and_align_of(cx, element_llvm_type);
 302
 303     let (array_size_in_bytes, upper_bound) = match len {
 304         Some(len) => (element_type_size * len, len as c_longlong),
 305         None => (0, -1)
 306     };
 307
 308     let subrange = unsafe {
 309         llvm::LLVMRustDIBuilderGetOrCreateSubrange(DIB(cx), 0, upper_bound)
 310     };
 311
 312     let subscripts = create_DIArray(DIB(cx), &[subrange]);
 313     let metadata = unsafe {
 314         llvm::LLVMRustDIBuilderCreateArrayType(
 315             DIB(cx),
 316             bytes_to_bits(array_size_in_bytes),
 317             bytes_to_bits(element_type_align),
 318             element_type_metadata,
 319             subscripts)
 320     };
 321
 322     return MetadataCreationResult::new(metadata, false);
 323 }
 324
 325 fn vec_slice_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 326                                 vec_type: Ty<'tcx>,
 327                                 element_type: Ty<'tcx>,
 328                                 unique_type_id: UniqueTypeId,
 329                                 span: Span)
 330                                 -> MetadataCreationResult {
 331     let data_ptr_type = cx.tcx().mk_ptr(ty::TypeAndMut {
 332         ty: element_type,
 333         mutbl: hir::MutImmutable
 334     });
 335
 336     let element_type_metadata = type_metadata(cx, data_ptr_type, span);
 337
 338     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 339
 340     let slice_llvm_type = type_of::type_of(cx, vec_type);
 341     let slice_type_name = compute_debuginfo_type_name(cx, vec_type, true);
 342
 343     let member_llvm_types = slice_llvm_type.field_types();
 344     assert!(slice_layout_is_correct(cx,
 345                                     &member_llvm_types[..],
 346                                     element_type));
 347     let member_descriptions = [
 348         MemberDescription {
 349             name: "data_ptr".to_string(),
 350             llvm_type: member_llvm_types[0],
 351             type_metadata: element_type_metadata,
 352             offset: ComputedMemberOffset,
 353             flags: FLAGS_NONE
 354         },
 355         MemberDescription {
 356             name: "length".to_string(),
 357             llvm_type: member_llvm_types[1],
 358             type_metadata: type_metadata(cx, cx.tcx().types.usize, span),
 359             offset: ComputedMemberOffset,
 360             flags: FLAGS_NONE
 361         },
 362     ];
 363
 364     assert!(member_descriptions.len() == member_llvm_types.len());
 365
 366     let loc = span_start(cx, span);
 367     let file_metadata = file_metadata(cx, &loc.file.name, &loc.file.abs_path);
 368
 369     let metadata = composite_type_metadata(cx,
 370                                            slice_llvm_type,
 371                                            &slice_type_name[..],
 372                                            unique_type_id,
 373                                            &member_descriptions,
 374                                            NO_SCOPE_METADATA,
 375                                            file_metadata,
 376                                            span);
 377     return MetadataCreationResult::new(metadata, false);
 378
 379     fn slice_layout_is_correct<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 380                                          member_llvm_types: &[Type],
 381                                          element_type: Ty<'tcx>)
 382                                          -> bool {
 383         member_llvm_types.len() == 2 &&
 384         member_llvm_types[0] == type_of::type_of(cx, element_type).ptr_to() &&
 385         member_llvm_types[1] == cx.int_type()
 386     }
 387 }
 388
 389 fn subroutine_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 390                                       unique_type_id: UniqueTypeId,
 391                                       signature: &ty::PolyFnSig<'tcx>,
 392                                       span: Span)
 393                                       -> MetadataCreationResult
 394 {
 395     let signature = cx.tcx().erase_late_bound_regions(signature);
 396
 397     let mut signature_metadata: Vec<DIType> = Vec::with_capacity(signature.inputs.len() + 1);
 398
 399     // return type
 400     signature_metadata.push(match signature.output.sty {
 401         ty::TyTuple(ref tys) if tys.is_empty() => ptr::null_mut(),
 402         _ => type_metadata(cx, signature.output, span)
 403     });
 404
 405     // regular arguments
 406     for &argument_type in &signature.inputs {
 407         signature_metadata.push(type_metadata(cx, argument_type, span));
 408     }
 409
 410     return_if_metadata_created_in_meantime!(cx, unique_type_id);
 411
 412     return MetadataCreationResult::new(
 413         unsafe {
 414             llvm::LLVMRustDIBuilderCreateSubroutineType(
 415                 DIB(cx),
 416                 unknown_file_metadata(cx),
 417                 create_DIArray(DIB(cx), &signature_metadata[..]))
 418         },
 419         false);
 420 }
 421
 422 // FIXME(1563) This is all a bit of a hack because 'trait pointer' is an ill-
 423 // defined concept. For the case of an actual trait pointer (i.e., Box<Trait>,
 424 // &Trait), trait_object_type should be the whole thing (e.g, Box<Trait>) and
 425 // trait_type should be the actual trait (e.g., Trait). Where the trait is part
 426 // of a DST struct, there is no trait_object_type and the results of this
 427 // function will be a little bit weird.
 428 fn trait_pointer_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 429                                     trait_type: Ty<'tcx>,
 430                                     trait_object_type: Option<Ty<'tcx>>,
 431                                     unique_type_id: UniqueTypeId)
 432                                     -> DIType {
 433     // The implementation provided here is a stub. It makes sure that the trait
 434     // type is assigned the correct name, size, namespace, and source location.
 435     // But it does not describe the trait's methods.
 436
 437     let def_id = match trait_type.sty {
 438         ty::TyTrait(ref data) => data.principal.def_id(),
 439         _ => {
 440             bug!("debuginfo: Unexpected trait-object type in \
 441                   trait_pointer_metadata(): {:?}",
 442                  trait_type);
 443         }
 444     };
 445
 446     let trait_object_type = trait_object_type.unwrap_or(trait_type);
 447     let trait_type_name =
 448         compute_debuginfo_type_name(cx, trait_object_type, false);
 449
 450     let (containing_scope, _) = get_namespace_and_span_for_item(cx, def_id);
 451
 452     let trait_llvm_type = type_of::type_of(cx, trait_object_type);
 453     let file_metadata = unknown_file_metadata(cx);
 454
 455     composite_type_metadata(cx,
 456                             trait_llvm_type,
 457                             &trait_type_name[..],
 458                             unique_type_id,
 459                             &[],
 460                             containing_scope,
 461                             file_metadata,
 462                             syntax_pos::DUMMY_SP)
 463 }
 464
 465 pub fn type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 466                                t: Ty<'tcx>,
 467                                usage_site_span: Span)
 468                                -> DIType {
 469     // Get the unique type id of this type.
 470     let unique_type_id = {
 471         let mut type_map = debug_context(cx).type_map.borrow_mut();
 472         // First, try to find the type in TypeMap. If we have seen it before, we
 473         // can exit early here.
 474         match type_map.find_metadata_for_type(t) {
 475             Some(metadata) => {
 476                 return metadata;
 477             },
 478             None => {
 479                 // The Ty is not in the TypeMap but maybe we have already seen
 480                 // an equivalent type (e.g. only differing in region arguments).
 481                 // In order to find out, generate the unique type id and look
 482                 // that up.
 483                 let unique_type_id = type_map.get_unique_type_id_of_type(cx, t);
 484                 match type_map.find_metadata_for_unique_id(unique_type_id) {
 485                     Some(metadata) => {
 486                         // There is already an equivalent type in the TypeMap.
 487                         // Register this Ty as an alias in the cache and
 488                         // return the cached metadata.
 489                         type_map.register_type_with_metadata(t, metadata);
 490                         return metadata;
 491                     },
 492                     None => {
 493                         // There really is no type metadata for this type, so
 494                         // proceed by creating it.
 495                         unique_type_id
 496                     }
 497                 }
 498             }
 499         }
 500     };
 501
 502     debug!("type_metadata: {:?}", t);
 503
 504     let sty = &t.sty;
 505     let MetadataCreationResult { metadata, already_stored_in_typemap } = match *sty {
 506         ty::TyNever    |
 507         ty::TyBool     |
 508         ty::TyChar     |
 509         ty::TyInt(_)   |
 510         ty::TyUint(_)  |
 511         ty::TyFloat(_) => {
 512             MetadataCreationResult::new(basic_type_metadata(cx, t), false)
 513         }
 514         ty::TyTuple(ref elements) if elements.is_empty() => {
 515             MetadataCreationResult::new(basic_type_metadata(cx, t), false)
 516         }
 517         ty::TyArray(typ, len) => {
 518             fixed_vec_metadata(cx, unique_type_id, typ, Some(len as u64), usage_site_span)
 519         }
 520         ty::TySlice(typ) => {
 521             fixed_vec_metadata(cx, unique_type_id, typ, None, usage_site_span)
 522         }
 523         ty::TyStr => {
 524             fixed_vec_metadata(cx, unique_type_id, cx.tcx().types.i8, None, usage_site_span)
 525         }
 526         ty::TyTrait(..) => {
 527             MetadataCreationResult::new(
 528                         trait_pointer_metadata(cx, t, None, unique_type_id),
 529             false)
 530         }
 531         ty::TyBox(ty) |
 532         ty::TyRawPtr(ty::TypeAndMut{ty, ..}) |
 533         ty::TyRef(_, ty::TypeAndMut{ty, ..}) => {
 534             match ty.sty {
 535                 ty::TySlice(typ) => {
 536                     vec_slice_metadata(cx, t, typ, unique_type_id, usage_site_span)
 537                 }
 538                 ty::TyStr => {
 539                     vec_slice_metadata(cx, t, cx.tcx().types.u8, unique_type_id, usage_site_span)
 540                 }
 541                 ty::TyTrait(..) => {
 542                     MetadataCreationResult::new(
 543                         trait_pointer_metadata(cx, ty, Some(t), unique_type_id),
 544                         false)
 545                 }
 546                 _ => {
 547                     let pointee_metadata = type_metadata(cx, ty, usage_site_span);
 548
 549                     match debug_context(cx).type_map
 550                                            .borrow()
 551                                            .find_metadata_for_unique_id(unique_type_id) {
 552                         Some(metadata) => return metadata,
 553                         None => { /* proceed normally */ }
 554                     };
 555
 556                     MetadataCreationResult::new(pointer_type_metadata(cx, t, pointee_metadata),
 557                                                 false)
 558                 }
 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(_, ref substs) => {
 578             prepare_tuple_metadata(cx,
 579                                    t,
 580                                    &substs.upvar_tys,
 581                                    unique_type_id,
 582                                    usage_site_span).finalize(cx)
 583         }
 584         ty::TyAdt(def, ..) => match def.adt_kind() {
 585             AdtKind::Struct => {
 586                 prepare_struct_metadata(cx,
 587                                         t,
 588                                         unique_type_id,
 589                                         usage_site_span).finalize(cx)
 590             }
 591             AdtKind::Union => {
 592                 prepare_union_metadata(cx,
 593                                     t,
 594                                     unique_type_id,
 595                                     usage_site_span).finalize(cx)
 596             }
 597             AdtKind::Enum => {
 598                 prepare_enum_metadata(cx,
 599                                     t,
 600                                     def.did,
 601                                     unique_type_id,
 602                                     usage_site_span).finalize(cx)
 603             }
 604         },
 605         ty::TyTuple(ref elements) => {
 606             prepare_tuple_metadata(cx,
 607                                    t,
 608                                    &elements[..],
 609                                    unique_type_id,
 610                                    usage_site_span).finalize(cx)
 611         }
 612         _ => {
 613             bug!("debuginfo: unexpected type in type_metadata: {:?}", sty)
 614         }
 615     };
 616
 617     {
 618         let mut type_map = debug_context(cx).type_map.borrow_mut();
 619
 620         if already_stored_in_typemap {
 621             // Also make sure that we already have a TypeMap entry for the unique type id.
 622             let metadata_for_uid = match type_map.find_metadata_for_unique_id(unique_type_id) {
 623                 Some(metadata) => metadata,
 624                 None => {
 625                     let unique_type_id_str =
 626                         type_map.get_unique_type_id_as_string(unique_type_id);
 627                     span_bug!(usage_site_span,
 628                               "Expected type metadata for unique \
 629                                type id '{}' to already be in \
 630                                the debuginfo::TypeMap but it \
 631                                was not. (Ty = {})",
 632                               &unique_type_id_str[..],
 633                               t);
 634                 }
 635             };
 636
 637             match type_map.find_metadata_for_type(t) {
 638                 Some(metadata) => {
 639                     if metadata != metadata_for_uid {
 640                         let unique_type_id_str =
 641                             type_map.get_unique_type_id_as_string(unique_type_id);
 642                         span_bug!(usage_site_span,
 643                                   "Mismatch between Ty and \
 644                                    UniqueTypeId maps in \
 645                                    debuginfo::TypeMap. \
 646                                    UniqueTypeId={}, Ty={}",
 647                                   &unique_type_id_str[..],
 648                                   t);
 649                     }
 650                 }
 651                 None => {
 652                     type_map.register_type_with_metadata(t, metadata);
 653                 }
 654             }
 655         } else {
 656             type_map.register_type_with_metadata(t, metadata);
 657             type_map.register_unique_id_with_metadata(unique_type_id, metadata);
 658         }
 659     }
 660
 661     metadata
 662 }
 663
 664 pub fn file_metadata(cx: &CrateContext, path: &str, full_path: &Option<String>) -> DIFile {
 665     // FIXME (#9639): This needs to handle non-utf8 paths
 666     let work_dir = cx.sess().working_dir.to_str().unwrap();
 667     let file_name =
 668         full_path.as_ref().map(|p| p.as_str()).unwrap_or_else(|| {
 669             if path.starts_with(work_dir) {
 670                 &path[work_dir.len() + 1..path.len()]
 671             } else {
 672                 path
 673             }
 674         });
 675
 676     file_metadata_(cx, path, file_name, &work_dir)
 677 }
 678
 679 pub fn unknown_file_metadata(cx: &CrateContext) -> DIFile {
 680     // Regular filenames should not be empty, so we abuse an empty name as the
 681     // key for the special unknown file metadata
 682     file_metadata_(cx, "", "<unknown>", "")
 683
 684 }
 685
 686 fn file_metadata_(cx: &CrateContext, key: &str, file_name: &str, work_dir: &str) -> DIFile {
 687     if let Some(file_metadata) = debug_context(cx).created_files.borrow().get(key) {
 688         return *file_metadata;
 689     }
 690
 691     debug!("file_metadata: file_name: {}, work_dir: {}", file_name, work_dir);
 692
 693     let file_name = CString::new(file_name).unwrap();
 694     let work_dir = CString::new(work_dir).unwrap();
 695     let file_metadata = unsafe {
 696         llvm::LLVMRustDIBuilderCreateFile(DIB(cx), file_name.as_ptr(),
 697                                           work_dir.as_ptr())
 698     };
 699
 700     let mut created_files = debug_context(cx).created_files.borrow_mut();
 701     created_files.insert(key.to_string(), file_metadata);
 702     file_metadata
 703 }
 704
 705 fn basic_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 706                                  t: Ty<'tcx>) -> DIType {
 707
 708     debug!("basic_type_metadata: {:?}", t);
 709
 710     let (name, encoding) = match t.sty {
 711         ty::TyNever => ("!", DW_ATE_unsigned),
 712         ty::TyTuple(ref elements) if elements.is_empty() =>
 713             ("()", DW_ATE_unsigned),
 714         ty::TyBool => ("bool", DW_ATE_boolean),
 715         ty::TyChar => ("char", DW_ATE_unsigned_char),
 716         ty::TyInt(int_ty) => {
 717             (int_ty.ty_to_string(), DW_ATE_signed)
 718         },
 719         ty::TyUint(uint_ty) => {
 720             (uint_ty.ty_to_string(), DW_ATE_unsigned)
 721         },
 722         ty::TyFloat(float_ty) => {
 723             (float_ty.ty_to_string(), DW_ATE_float)
 724         },
 725         _ => bug!("debuginfo::basic_type_metadata - t is invalid type")
 726     };
 727
 728     let llvm_type = type_of::type_of(cx, t);
 729     let (size, align) = size_and_align_of(cx, llvm_type);
 730     let name = CString::new(name).unwrap();
 731     let ty_metadata = unsafe {
 732         llvm::LLVMRustDIBuilderCreateBasicType(
 733             DIB(cx),
 734             name.as_ptr(),
 735             bytes_to_bits(size),
 736             bytes_to_bits(align),
 737             encoding)
 738     };
 739
 740     return ty_metadata;
 741 }
 742
 743 fn pointer_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 744                                    pointer_type: Ty<'tcx>,
 745                                    pointee_type_metadata: DIType)
 746                                    -> DIType {
 747     let pointer_llvm_type = type_of::type_of(cx, pointer_type);
 748     let (pointer_size, pointer_align) = size_and_align_of(cx, pointer_llvm_type);
 749     let name = compute_debuginfo_type_name(cx, pointer_type, false);
 750     let name = CString::new(name).unwrap();
 751     let ptr_metadata = unsafe {
 752         llvm::LLVMRustDIBuilderCreatePointerType(
 753             DIB(cx),
 754             pointee_type_metadata,
 755             bytes_to_bits(pointer_size),
 756             bytes_to_bits(pointer_align),
 757             name.as_ptr())
 758     };
 759     return ptr_metadata;
 760 }
 761
 762 pub fn compile_unit_metadata(scc: &SharedCrateContext,
 763                              debug_context: &CrateDebugContext,
 764                              sess: &Session)
 765                              -> DIDescriptor {
 766     let work_dir = &sess.working_dir;
 767     let compile_unit_name = match sess.local_crate_source_file {
 768         None => fallback_path(scc),
 769         Some(ref abs_path) => {
 770             if abs_path.is_relative() {
 771                 sess.warn("debuginfo: Invalid path to crate's local root source file!");
 772                 fallback_path(scc)
 773             } else {
 774                 match abs_path.strip_prefix(work_dir) {
 775                     Ok(ref p) if p.is_relative() => {
 776                         if p.starts_with(Path::new("./")) {
 777                             path2cstr(p)
 778                         } else {
 779                             path2cstr(&Path::new(".").join(p))
 780                         }
 781                     }
 782                     _ => fallback_path(scc)
 783                 }
 784             }
 785         }
 786     };
 787
 788     debug!("compile_unit_metadata: {:?}", compile_unit_name);
 789     let producer = format!("rustc version {}",
 790                            (option_env!("CFG_VERSION")).expect("CFG_VERSION"));
 791
 792     let compile_unit_name = compile_unit_name.as_ptr();
 793     let work_dir = path2cstr(&work_dir);
 794     let producer = CString::new(producer).unwrap();
 795     let flags = "\0";
 796     let split_name = "\0";
 797     return unsafe {
 798         llvm::LLVMRustDIBuilderCreateCompileUnit(
 799             debug_context.builder,
 800             DW_LANG_RUST,
 801             compile_unit_name,
 802             work_dir.as_ptr(),
 803             producer.as_ptr(),
 804             sess.opts.optimize != config::OptLevel::No,
 805             flags.as_ptr() as *const _,
 806             0,
 807             split_name.as_ptr() as *const _)
 808     };
 809
 810     fn fallback_path(scc: &SharedCrateContext) -> CString {
 811         CString::new(scc.link_meta().crate_name.clone()).unwrap()
 812     }
 813 }
 814
 815 struct MetadataCreationResult {
 816     metadata: DIType,
 817     already_stored_in_typemap: bool
 818 }
 819
 820 impl MetadataCreationResult {
 821     fn new(metadata: DIType, already_stored_in_typemap: bool) -> MetadataCreationResult {
 822         MetadataCreationResult {
 823             metadata: metadata,
 824             already_stored_in_typemap: already_stored_in_typemap
 825         }
 826     }
 827 }
 828
 829 #[derive(Debug)]
 830 enum MemberOffset {
 831     FixedMemberOffset { bytes: usize },
 832     // For ComputedMemberOffset, the offset is read from the llvm type definition.
 833     ComputedMemberOffset
 834 }
 835
 836 // Description of a type member, which can either be a regular field (as in
 837 // structs or tuples) or an enum variant.
 838 #[derive(Debug)]
 839 struct MemberDescription {
 840     name: String,
 841     llvm_type: Type,
 842     type_metadata: DIType,
 843     offset: MemberOffset,
 844     flags: c_uint
 845 }
 846
 847 // A factory for MemberDescriptions. It produces a list of member descriptions
 848 // for some record-like type. MemberDescriptionFactories are used to defer the
 849 // creation of type member descriptions in order to break cycles arising from
 850 // recursive type definitions.
 851 enum MemberDescriptionFactory<'tcx> {
 852     StructMDF(StructMemberDescriptionFactory<'tcx>),
 853     TupleMDF(TupleMemberDescriptionFactory<'tcx>),
 854     EnumMDF(EnumMemberDescriptionFactory<'tcx>),
 855     UnionMDF(UnionMemberDescriptionFactory<'tcx>),
 856     VariantMDF(VariantMemberDescriptionFactory<'tcx>)
 857 }
 858
 859 impl<'tcx> MemberDescriptionFactory<'tcx> {
 860     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 861                                       -> Vec<MemberDescription> {
 862         match *self {
 863             StructMDF(ref this) => {
 864                 this.create_member_descriptions(cx)
 865             }
 866             TupleMDF(ref this) => {
 867                 this.create_member_descriptions(cx)
 868             }
 869             EnumMDF(ref this) => {
 870                 this.create_member_descriptions(cx)
 871             }
 872             UnionMDF(ref this) => {
 873                 this.create_member_descriptions(cx)
 874             }
 875             VariantMDF(ref this) => {
 876                 this.create_member_descriptions(cx)
 877             }
 878         }
 879     }
 880 }
 881
 882 //=-----------------------------------------------------------------------------
 883 // Structs
 884 //=-----------------------------------------------------------------------------
 885
 886 // Creates MemberDescriptions for the fields of a struct
 887 struct StructMemberDescriptionFactory<'tcx> {
 888     variant: ty::VariantDef<'tcx>,
 889     substs: &'tcx Substs<'tcx>,
 890     is_simd: bool,
 891     span: Span,
 892 }
 893
 894 impl<'tcx> StructMemberDescriptionFactory<'tcx> {
 895     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 896                                       -> Vec<MemberDescription> {
 897         let field_size = if self.is_simd {
 898             let fty = monomorphize::field_ty(cx.tcx(),
 899                                              self.substs,
 900                                              &self.variant.fields[0]);
 901             Some(machine::llsize_of_alloc(
 902                 cx,
 903                 type_of::type_of(cx, fty)
 904             ) as usize)
 905         } else {
 906             None
 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 = if self.is_simd {
 918                 FixedMemberOffset { bytes: i * field_size.unwrap() }
 919             } else {
 920                 ComputedMemberOffset
 921             };
 922
 923             MemberDescription {
 924                 name: name,
 925                 llvm_type: type_of::type_of(cx, fty),
 926                 type_metadata: type_metadata(cx, fty, self.span),
 927                 offset: offset,
 928                 flags: FLAGS_NONE,
 929             }
 930         }).collect()
 931     }
 932 }
 933
 934
 935 fn prepare_struct_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 936                                      struct_type: Ty<'tcx>,
 937                                      unique_type_id: UniqueTypeId,
 938                                      span: Span)
 939                                      -> RecursiveTypeDescription<'tcx> {
 940     let struct_name = compute_debuginfo_type_name(cx, struct_type, false);
 941     let struct_llvm_type = type_of::in_memory_type_of(cx, struct_type);
 942
 943     let (struct_def_id, variant, substs) = match struct_type.sty {
 944         ty::TyAdt(def, substs) => (def.did, def.struct_variant(), substs),
 945         _ => bug!("prepare_struct_metadata on a non-ADT")
 946     };
 947
 948     let (containing_scope, _) = get_namespace_and_span_for_item(cx, struct_def_id);
 949
 950     let struct_metadata_stub = create_struct_stub(cx,
 951                                                   struct_llvm_type,
 952                                                   &struct_name,
 953                                                   unique_type_id,
 954                                                   containing_scope);
 955
 956     create_and_register_recursive_type_forward_declaration(
 957         cx,
 958         struct_type,
 959         unique_type_id,
 960         struct_metadata_stub,
 961         struct_llvm_type,
 962         StructMDF(StructMemberDescriptionFactory {
 963             variant: variant,
 964             substs: substs,
 965             is_simd: struct_type.is_simd(),
 966             span: span,
 967         })
 968     )
 969 }
 970
 971 //=-----------------------------------------------------------------------------
 972 // Tuples
 973 //=-----------------------------------------------------------------------------
 974
 975 // Creates MemberDescriptions for the fields of a tuple
 976 struct TupleMemberDescriptionFactory<'tcx> {
 977     component_types: Vec<Ty<'tcx>>,
 978     span: Span,
 979 }
 980
 981 impl<'tcx> TupleMemberDescriptionFactory<'tcx> {
 982     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
 983                                       -> Vec<MemberDescription> {
 984         self.component_types
 985             .iter()
 986             .enumerate()
 987             .map(|(i, &component_type)| {
 988             MemberDescription {
 989                 name: format!("__{}", i),
 990                 llvm_type: type_of::type_of(cx, component_type),
 991                 type_metadata: type_metadata(cx, component_type, self.span),
 992                 offset: ComputedMemberOffset,
 993                 flags: FLAGS_NONE,
 994             }
 995         }).collect()
 996     }
 997 }
 998
 999 fn prepare_tuple_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1000                                     tuple_type: Ty<'tcx>,
1001                                     component_types: &[Ty<'tcx>],
1002                                     unique_type_id: UniqueTypeId,
1003                                     span: Span)
1004                                     -> RecursiveTypeDescription<'tcx> {
1005     let tuple_name = compute_debuginfo_type_name(cx, tuple_type, false);
1006     let tuple_llvm_type = type_of::type_of(cx, tuple_type);
1007
1008     create_and_register_recursive_type_forward_declaration(
1009         cx,
1010         tuple_type,
1011         unique_type_id,
1012         create_struct_stub(cx,
1013                            tuple_llvm_type,
1014                            &tuple_name[..],
1015                            unique_type_id,
1016                            NO_SCOPE_METADATA),
1017         tuple_llvm_type,
1018         TupleMDF(TupleMemberDescriptionFactory {
1019             component_types: component_types.to_vec(),
1020             span: span,
1021         })
1022     )
1023 }
1024
1025 //=-----------------------------------------------------------------------------
1026 // Unions
1027 //=-----------------------------------------------------------------------------
1028
1029 struct UnionMemberDescriptionFactory<'tcx> {
1030     variant: ty::VariantDef<'tcx>,
1031     substs: &'tcx Substs<'tcx>,
1032     span: Span,
1033 }
1034
1035 impl<'tcx> UnionMemberDescriptionFactory<'tcx> {
1036     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1037                                       -> Vec<MemberDescription> {
1038         self.variant.fields.iter().map(|field| {
1039             let fty = monomorphize::field_ty(cx.tcx(), self.substs, field);
1040             MemberDescription {
1041                 name: field.name.to_string(),
1042                 llvm_type: type_of::type_of(cx, fty),
1043                 type_metadata: type_metadata(cx, fty, self.span),
1044                 offset: FixedMemberOffset { bytes: 0 },
1045                 flags: FLAGS_NONE,
1046             }
1047         }).collect()
1048     }
1049 }
1050
1051 fn prepare_union_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1052                                     union_type: Ty<'tcx>,
1053                                     unique_type_id: UniqueTypeId,
1054                                     span: Span)
1055                                     -> RecursiveTypeDescription<'tcx> {
1056     let union_name = compute_debuginfo_type_name(cx, union_type, false);
1057     let union_llvm_type = type_of::in_memory_type_of(cx, union_type);
1058
1059     let (union_def_id, variant, substs) = match union_type.sty {
1060         ty::TyAdt(def, substs) => (def.did, def.struct_variant(), substs),
1061         _ => bug!("prepare_union_metadata on a non-ADT")
1062     };
1063
1064     let (containing_scope, _) = get_namespace_and_span_for_item(cx, union_def_id);
1065
1066     let union_metadata_stub = create_union_stub(cx,
1067                                                 union_llvm_type,
1068                                                 &union_name,
1069                                                 unique_type_id,
1070                                                 containing_scope);
1071
1072     create_and_register_recursive_type_forward_declaration(
1073         cx,
1074         union_type,
1075         unique_type_id,
1076         union_metadata_stub,
1077         union_llvm_type,
1078         UnionMDF(UnionMemberDescriptionFactory {
1079             variant: variant,
1080             substs: substs,
1081             span: span,
1082         })
1083     )
1084 }
1085
1086 //=-----------------------------------------------------------------------------
1087 // Enums
1088 //=-----------------------------------------------------------------------------
1089
1090 // Describes the members of an enum value: An enum is described as a union of
1091 // structs in DWARF. This MemberDescriptionFactory provides the description for
1092 // the members of this union; so for every variant of the given enum, this
1093 // factory will produce one MemberDescription (all with no name and a fixed
1094 // offset of zero bytes).
1095 struct EnumMemberDescriptionFactory<'tcx> {
1096     enum_type: Ty<'tcx>,
1097     type_rep: &'tcx layout::Layout,
1098     discriminant_type_metadata: Option<DIType>,
1099     containing_scope: DIScope,
1100     file_metadata: DIFile,
1101     span: Span,
1102 }
1103
1104 impl<'tcx> EnumMemberDescriptionFactory<'tcx> {
1105     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1106                                       -> Vec<MemberDescription> {
1107         let adt = &self.enum_type.ty_adt_def().unwrap();
1108         let substs = match self.enum_type.sty {
1109             ty::TyAdt(def, ref s) if def.adt_kind() == AdtKind::Enum => s,
1110             _ => bug!("{} is not an enum", self.enum_type)
1111         };
1112         match *self.type_rep {
1113             layout::General { ref variants, .. } => {
1114                 let discriminant_info = RegularDiscriminant(self.discriminant_type_metadata
1115                     .expect(""));
1116                 variants
1117                     .iter()
1118                     .enumerate()
1119                     .map(|(i, struct_def)| {
1120                         let (variant_type_metadata,
1121                              variant_llvm_type,
1122                              member_desc_factory) =
1123                             describe_enum_variant(cx,
1124                                                   self.enum_type,
1125                                                   struct_def,
1126                                                   &adt.variants[i],
1127                                                   discriminant_info,
1128                                                   self.containing_scope,
1129                                                   self.span);
1130
1131                         let member_descriptions = member_desc_factory
1132                             .create_member_descriptions(cx);
1133
1134                         set_members_of_composite_type(cx,
1135                                                       variant_type_metadata,
1136                                                       variant_llvm_type,
1137                                                       &member_descriptions);
1138                         MemberDescription {
1139                             name: "".to_string(),
1140                             llvm_type: variant_llvm_type,
1141                             type_metadata: variant_type_metadata,
1142                             offset: FixedMemberOffset { bytes: 0 },
1143                             flags: FLAGS_NONE
1144                         }
1145                     }).collect()
1146             },
1147             layout::Univariant{ ref variant, .. } => {
1148                 assert!(adt.variants.len() <= 1);
1149
1150                 if adt.variants.is_empty() {
1151                     vec![]
1152                 } else {
1153                     let (variant_type_metadata,
1154                          variant_llvm_type,
1155                          member_description_factory) =
1156                         describe_enum_variant(cx,
1157                                               self.enum_type,
1158                                               variant,
1159                                               &adt.variants[0],
1160                                               NoDiscriminant,
1161                                               self.containing_scope,
1162                                               self.span);
1163
1164                     let member_descriptions =
1165                         member_description_factory.create_member_descriptions(cx);
1166
1167                     set_members_of_composite_type(cx,
1168                                                   variant_type_metadata,
1169                                                   variant_llvm_type,
1170                                                   &member_descriptions[..]);
1171                     vec![
1172                         MemberDescription {
1173                             name: "".to_string(),
1174                             llvm_type: variant_llvm_type,
1175                             type_metadata: variant_type_metadata,
1176                             offset: FixedMemberOffset { bytes: 0 },
1177                             flags: FLAGS_NONE
1178                         }
1179                     ]
1180                 }
1181             }
1182             layout::RawNullablePointer { nndiscr: non_null_variant_index, .. } => {
1183                 // As far as debuginfo is concerned, the pointer this enum
1184                 // represents is still wrapped in a struct. This is to make the
1185                 // DWARF representation of enums uniform.
1186
1187                 // First create a description of the artificial wrapper struct:
1188                 let non_null_variant = &adt.variants[non_null_variant_index as usize];
1189                 let non_null_variant_name = non_null_variant.name.as_str();
1190
1191                 // The llvm type and metadata of the pointer
1192                 let nnty = monomorphize::field_ty(cx.tcx(), &substs, &non_null_variant.fields[0] );
1193                 let non_null_llvm_type = type_of::type_of(cx, nnty);
1194                 let non_null_type_metadata = type_metadata(cx, nnty, self.span);
1195
1196                 // The type of the artificial struct wrapping the pointer
1197                 let artificial_struct_llvm_type = Type::struct_(cx,
1198                                                                 &[non_null_llvm_type],
1199                                                                 false);
1200
1201                 // For the metadata of the wrapper struct, we need to create a
1202                 // MemberDescription of the struct's single field.
1203                 let sole_struct_member_description = MemberDescription {
1204                     name: match non_null_variant.ctor_kind {
1205                         CtorKind::Fn => "__0".to_string(),
1206                         CtorKind::Fictive => {
1207                             non_null_variant.fields[0].name.to_string()
1208                         }
1209                         CtorKind::Const => bug!()
1210                     },
1211                     llvm_type: non_null_llvm_type,
1212                     type_metadata: non_null_type_metadata,
1213                     offset: FixedMemberOffset { bytes: 0 },
1214                     flags: FLAGS_NONE
1215                 };
1216
1217                 let unique_type_id = debug_context(cx).type_map
1218                                                       .borrow_mut()
1219                                                       .get_unique_type_id_of_enum_variant(
1220                                                           cx,
1221                                                           self.enum_type,
1222                                                           &non_null_variant_name);
1223
1224                 // Now we can create the metadata of the artificial struct
1225                 let artificial_struct_metadata =
1226                     composite_type_metadata(cx,
1227                                             artificial_struct_llvm_type,
1228                                             &non_null_variant_name,
1229                                             unique_type_id,
1230                                             &[sole_struct_member_description],
1231                                             self.containing_scope,
1232                                             self.file_metadata,
1233                                             syntax_pos::DUMMY_SP);
1234
1235                 // Encode the information about the null variant in the union
1236                 // member's name.
1237                 let null_variant_index = (1 - non_null_variant_index) as usize;
1238                 let null_variant_name = adt.variants[null_variant_index].name;
1239                 let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
1240                                                 0,
1241                                                 null_variant_name);
1242
1243                 // Finally create the (singleton) list of descriptions of union
1244                 // members.
1245                 vec![
1246                     MemberDescription {
1247                         name: union_member_name,
1248                         llvm_type: artificial_struct_llvm_type,
1249                         type_metadata: artificial_struct_metadata,
1250                         offset: FixedMemberOffset { bytes: 0 },
1251                         flags: FLAGS_NONE
1252                     }
1253                 ]
1254             },
1255             layout::StructWrappedNullablePointer { nonnull: ref struct_def,
1256                                                 nndiscr,
1257                                                 ref discrfield, ..} => {
1258                 // Create a description of the non-null variant
1259                 let (variant_type_metadata, variant_llvm_type, member_description_factory) =
1260                     describe_enum_variant(cx,
1261                                           self.enum_type,
1262                                           struct_def,
1263                                           &adt.variants[nndiscr as usize],
1264                                           OptimizedDiscriminant,
1265                                           self.containing_scope,
1266                                           self.span);
1267
1268                 let variant_member_descriptions =
1269                     member_description_factory.create_member_descriptions(cx);
1270
1271                 set_members_of_composite_type(cx,
1272                                               variant_type_metadata,
1273                                               variant_llvm_type,
1274                                               &variant_member_descriptions[..]);
1275
1276                 // Encode the information about the null variant in the union
1277                 // member's name.
1278                 let null_variant_index = (1 - nndiscr) as usize;
1279                 let null_variant_name = adt.variants[null_variant_index].name;
1280                 let discrfield = discrfield.iter()
1281                                            .skip(1)
1282                                            .map(|x| x.to_string())
1283                                            .collect::<Vec<_>>().join("$");
1284                 let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
1285                                                 discrfield,
1286                                                 null_variant_name);
1287
1288                 // Create the (singleton) list of descriptions of union members.
1289                 vec![
1290                     MemberDescription {
1291                         name: union_member_name,
1292                         llvm_type: variant_llvm_type,
1293                         type_metadata: variant_type_metadata,
1294                         offset: FixedMemberOffset { bytes: 0 },
1295                         flags: FLAGS_NONE
1296                     }
1297                 ]
1298             },
1299             layout::CEnum { .. } => span_bug!(self.span, "This should be unreachable."),
1300             ref l @ _ => bug!("Not an enum layout: {:#?}", l)
1301         }
1302     }
1303 }
1304
1305 // Creates MemberDescriptions for the fields of a single enum variant.
1306 struct VariantMemberDescriptionFactory<'tcx> {
1307     args: Vec<(String, Ty<'tcx>)>,
1308     discriminant_type_metadata: Option<DIType>,
1309     span: Span,
1310 }
1311
1312 impl<'tcx> VariantMemberDescriptionFactory<'tcx> {
1313     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
1314                                       -> Vec<MemberDescription> {
1315         self.args.iter().enumerate().map(|(i, &(ref name, ty))| {
1316             MemberDescription {
1317                 name: name.to_string(),
1318                 llvm_type: type_of::type_of(cx, ty),
1319                 type_metadata: match self.discriminant_type_metadata {
1320                     Some(metadata) if i == 0 => metadata,
1321                     _ => type_metadata(cx, ty, self.span)
1322                 },
1323                 offset: ComputedMemberOffset,
1324                 flags: FLAGS_NONE
1325             }
1326         }).collect()
1327     }
1328 }
1329
1330 #[derive(Copy, Clone)]
1331 enum EnumDiscriminantInfo {
1332     RegularDiscriminant(DIType),
1333     OptimizedDiscriminant,
1334     NoDiscriminant
1335 }
1336
1337 // Returns a tuple of (1) type_metadata_stub of the variant, (2) the llvm_type
1338 // of the variant, and (3) a MemberDescriptionFactory for producing the
1339 // descriptions of the fields of the variant. This is a rudimentary version of a
1340 // full RecursiveTypeDescription.
1341 fn describe_enum_variant<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1342                                    enum_type: Ty<'tcx>,
1343                                    struct_def: &layout::Struct,
1344                                    variant: ty::VariantDef<'tcx>,
1345                                    discriminant_info: EnumDiscriminantInfo,
1346                                    containing_scope: DIScope,
1347                                    span: Span)
1348                                    -> (DICompositeType, Type, MemberDescriptionFactory<'tcx>) {
1349     let substs = match enum_type.sty {
1350         ty::TyAdt(def, s) if def.adt_kind() == AdtKind::Enum => s,
1351         ref t @ _ => bug!("{:#?} is not an enum", t)
1352     };
1353
1354     let maybe_discr_and_signed: Option<(layout::Integer, bool)> = match *cx.layout_of(enum_type) {
1355         layout::CEnum {discr, ..} => Some((discr, true)),
1356         layout::General{discr, ..} => Some((discr, false)),
1357         layout::Univariant { .. }
1358         | layout::RawNullablePointer { .. }
1359         | layout::StructWrappedNullablePointer { .. } => None,
1360         ref l @ _ => bug!("This should be unreachable. Type is {:#?} layout is {:#?}", enum_type, l)
1361     };
1362
1363     let mut field_tys = variant.fields.iter().map(|f: ty::FieldDef<'tcx>| {
1364         monomorphize::field_ty(cx.tcx(), &substs, f)
1365     }).collect::<Vec<_>>();
1366
1367     if let Some((discr, signed)) = maybe_discr_and_signed {
1368         field_tys.insert(0, discr.to_ty(&cx.tcx(), signed));
1369     }
1370
1371
1372     let variant_llvm_type =
1373         Type::struct_(cx, &field_tys
1374                                     .iter()
1375                                     .map(|t| type_of::type_of(cx, t))
1376                                     .collect::<Vec<_>>()
1377                                     ,
1378                       struct_def.packed);
1379     // Could do some consistency checks here: size, align, field count, discr type
1380
1381     let variant_name = variant.name.as_str();
1382     let unique_type_id = debug_context(cx).type_map
1383                                           .borrow_mut()
1384                                           .get_unique_type_id_of_enum_variant(
1385                                               cx,
1386                                               enum_type,
1387                                               &variant_name);
1388
1389     let metadata_stub = create_struct_stub(cx,
1390                                            variant_llvm_type,
1391                                            &variant_name,
1392                                            unique_type_id,
1393                                            containing_scope);
1394
1395     // Get the argument names from the enum variant info
1396     let mut arg_names: Vec<_> = match variant.ctor_kind {
1397         CtorKind::Const => vec![],
1398         CtorKind::Fn => {
1399             variant.fields
1400                    .iter()
1401                    .enumerate()
1402                    .map(|(i, _)| format!("__{}", i))
1403                    .collect()
1404         }
1405         CtorKind::Fictive => {
1406             variant.fields
1407                    .iter()
1408                    .map(|f| f.name.to_string())
1409                    .collect()
1410         }
1411     };
1412
1413     // If this is not a univariant enum, there is also the discriminant field.
1414     match discriminant_info {
1415         RegularDiscriminant(_) => arg_names.insert(0, "RUST$ENUM$DISR".to_string()),
1416         _ => { /* do nothing */ }
1417     };
1418
1419     // Build an array of (field name, field type) pairs to be captured in the factory closure.
1420     let args: Vec<(String, Ty)> = arg_names.iter()
1421         .zip(field_tys.iter())
1422         .map(|(s, &t)| (s.to_string(), t))
1423         .collect();
1424
1425     let member_description_factory =
1426         VariantMDF(VariantMemberDescriptionFactory {
1427             args: args,
1428             discriminant_type_metadata: match discriminant_info {
1429                 RegularDiscriminant(discriminant_type_metadata) => {
1430                     Some(discriminant_type_metadata)
1431                 }
1432                 _ => None
1433             },
1434             span: span,
1435         });
1436
1437     (metadata_stub, variant_llvm_type, member_description_factory)
1438 }
1439
1440 fn prepare_enum_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
1441                                    enum_type: Ty<'tcx>,
1442                                    enum_def_id: DefId,
1443                                    unique_type_id: UniqueTypeId,
1444                                    span: Span)
1445                                    -> RecursiveTypeDescription<'tcx> {
1446     let enum_name = compute_debuginfo_type_name(cx, enum_type, false);
1447
1448     let (containing_scope, _) = get_namespace_and_span_for_item(cx, enum_def_id);
1449     // FIXME: This should emit actual file metadata for the enum, but we
1450     // currently can't get the necessary information when it comes to types
1451     // imported from other crates. Formerly we violated the ODR when performing
1452     // LTO because we emitted debuginfo for the same type with varying file
1453     // metadata, so as a workaround we pretend that the type comes from
1454     // <unknown>
1455     let file_metadata = unknown_file_metadata(cx);
1456
1457     let variants = &enum_type.ty_adt_def().unwrap().variants;
1458     let enumerators_metadata: Vec<DIDescriptor> = variants
1459         .iter()
1460         .map(|v| {
1461             let token = v.name.as_str();
1462             let name = CString::new(token.as_bytes()).unwrap();
1463             unsafe {
1464                 llvm::LLVMRustDIBuilderCreateEnumerator(
1465                     DIB(cx),
1466                     name.as_ptr(),
1467                     v.disr_val.to_u64_unchecked())
1468             }
1469         })
1470         .collect();
1471
1472     let discriminant_type_metadata = |inttype: layout::Integer, signed: bool| {
1473         let disr_type_key = (enum_def_id, inttype);
1474         let cached_discriminant_type_metadata = debug_context(cx).created_enum_disr_types
1475                                                                  .borrow()
1476                                                                  .get(&disr_type_key).cloned();
1477         match cached_discriminant_type_metadata {
1478             Some(discriminant_type_metadata) => discriminant_type_metadata,
1479             None => {
1480                 let discriminant_llvm_type = Type::from_integer(cx, inttype);
1481                 let (discriminant_size, discriminant_align) =
1482                     size_and_align_of(cx, discriminant_llvm_type);
1483                 let discriminant_base_type_metadata =
1484                     type_metadata(cx,
1485                                   inttype.to_ty(&cx.tcx(), signed),
1486                                   syntax_pos::DUMMY_SP);
1487                 let discriminant_name = get_enum_discriminant_name(cx, enum_def_id);
1488
1489                 let name = CString::new(discriminant_name.as_bytes()).unwrap();
1490                 let discriminant_type_metadata = unsafe {
1491                     llvm::LLVMRustDIBuilderCreateEnumerationType(
1492                         DIB(cx),
1493                         containing_scope,
1494                         name.as_ptr(),
1495                         file_metadata,
1496                         UNKNOWN_LINE_NUMBER,
1497                         bytes_to_bits(discriminant_size),
1498                         bytes_to_bits(discriminant_align),
1499                         create_DIArray(DIB(cx), &enumerators_metadata),
1500                         discriminant_base_type_metadata)
1501                 };
1502
1503                 debug_context(cx).created_enum_disr_types
1504                                  .borrow_mut()
1505                                  .insert(disr_type_key, discriminant_type_metadata);
1506
1507                 discriminant_type_metadata
1508             }
1509         }
1510     };
1511
1512     let type_rep = cx.layout_of(enum_type);
1513
1514     let discriminant_type_metadata = match *type_rep {
1515         layout::CEnum { discr, signed, .. } => {
1516             return FinalMetadata(discriminant_type_metadata(discr, signed))
1517         },
1518         layout::RawNullablePointer { .. }           |
1519         layout::StructWrappedNullablePointer { .. } |
1520         layout::Univariant { .. }                      => None,
1521         layout::General { discr, .. } => Some(discriminant_type_metadata(discr, false)),
1522         ref l @ _ => bug!("Not an enum layout: {:#?}", l)
1523     };
1524
1525     let enum_llvm_type = type_of::type_of(cx, enum_type);
1526     let (enum_type_size, enum_type_align) = size_and_align_of(cx, enum_llvm_type);
1527
1528     let unique_type_id_str = debug_context(cx)
1529                              .type_map
1530                              .borrow()
1531                              .get_unique_type_id_as_string(unique_type_id);
1532
1533     let enum_name = CString::new(enum_name).unwrap();
1534     let unique_type_id_str = CString::new(unique_type_id_str.as_bytes()).unwrap();
1535     let enum_metadata = unsafe {
1536         llvm::LLVMRustDIBuilderCreateUnionType(
1537         DIB(cx),
1538         containing_scope,
1539         enum_name.as_ptr(),
1540         file_metadata,
1541         UNKNOWN_LINE_NUMBER,
1542         bytes_to_bits(enum_type_size),
1543         bytes_to_bits(enum_type_align),
1544         0, // Flags
1545         ptr::null_mut(),
1546         0, // RuntimeLang
1547         unique_type_id_str.as_ptr())
1548     };
1549
1550     return create_and_register_recursive_type_forward_declaration(
1551         cx,
1552         enum_type,
1553         unique_type_id,
1554         enum_metadata,
1555         enum_llvm_type,
1556         EnumMDF(EnumMemberDescriptionFactory {
1557             enum_type: enum_type,
1558             type_rep: type_rep,
1559             discriminant_type_metadata: discriminant_type_metadata,
1560             containing_scope: containing_scope,
1561             file_metadata: file_metadata,
1562             span: span,
1563         }),
1564     );
1565
1566     fn get_enum_discriminant_name(cx: &CrateContext,
1567                                   def_id: DefId)
1568                                   -> token::InternedString {
1569         cx.tcx().item_name(def_id).as_str()
1570     }
1571 }
1572
1573 /// Creates debug information for a composite type, that is, anything that
1574 /// results in a LLVM struct.
1575 ///
1576 /// Examples of Rust types to use this are: structs, tuples, boxes, vecs, and enums.
1577 fn composite_type_metadata(cx: &CrateContext,
1578                            composite_llvm_type: Type,
1579                            composite_type_name: &str,
1580                            composite_type_unique_id: UniqueTypeId,
1581                            member_descriptions: &[MemberDescription],
1582                            containing_scope: DIScope,
1583
1584                            // Ignore source location information as long as it
1585                            // can't be reconstructed for non-local crates.
1586                            _file_metadata: DIFile,
1587                            _definition_span: Span)
1588                            -> DICompositeType {
1589     // Create the (empty) struct metadata node ...
1590     let composite_type_metadata = create_struct_stub(cx,
1591                                                      composite_llvm_type,
1592                                                      composite_type_name,
1593                                                      composite_type_unique_id,
1594                                                      containing_scope);
1595     // ... and immediately create and add the member descriptions.
1596     set_members_of_composite_type(cx,
1597                                   composite_type_metadata,
1598                                   composite_llvm_type,
1599                                   member_descriptions);
1600
1601     return composite_type_metadata;
1602 }
1603
1604 fn set_members_of_composite_type(cx: &CrateContext,
1605                                  composite_type_metadata: DICompositeType,
1606                                  composite_llvm_type: Type,
1607                                  member_descriptions: &[MemberDescription]) {
1608     // In some rare cases LLVM metadata uniquing would lead to an existing type
1609     // description being used instead of a new one created in
1610     // create_struct_stub. This would cause a hard to trace assertion in
1611     // DICompositeType::SetTypeArray(). The following check makes sure that we
1612     // get a better error message if this should happen again due to some
1613     // regression.
1614     {
1615         let mut composite_types_completed =
1616             debug_context(cx).composite_types_completed.borrow_mut();
1617         if composite_types_completed.contains(&composite_type_metadata) {
1618             bug!("debuginfo::set_members_of_composite_type() - \
1619                   Already completed forward declaration re-encountered.");
1620         } else {
1621             composite_types_completed.insert(composite_type_metadata);
1622         }
1623     }
1624
1625     let member_metadata: Vec<DIDescriptor> = member_descriptions
1626         .iter()
1627         .enumerate()
1628         .map(|(i, member_description)| {
1629             let (member_size, member_align) = size_and_align_of(cx, member_description.llvm_type);
1630             let member_offset = match member_description.offset {
1631                 FixedMemberOffset { bytes } => bytes as u64,
1632                 ComputedMemberOffset => machine::llelement_offset(cx, composite_llvm_type, i)
1633             };
1634
1635             let member_name = member_description.name.as_bytes();
1636             let member_name = CString::new(member_name).unwrap();
1637             unsafe {
1638                 llvm::LLVMRustDIBuilderCreateMemberType(
1639                     DIB(cx),
1640                     composite_type_metadata,
1641                     member_name.as_ptr(),
1642                     unknown_file_metadata(cx),
1643                     UNKNOWN_LINE_NUMBER,
1644                     bytes_to_bits(member_size),
1645                     bytes_to_bits(member_align),
1646                     bytes_to_bits(member_offset),
1647                     member_description.flags,
1648                     member_description.type_metadata)
1649             }
1650         })
1651         .collect();
1652
1653     unsafe {
1654         let type_array = create_DIArray(DIB(cx), &member_metadata[..]);
1655         llvm::LLVMRustDICompositeTypeSetTypeArray(
1656             DIB(cx), composite_type_metadata, type_array);
1657     }
1658 }
1659
1660 // A convenience wrapper around LLVMRustDIBuilderCreateStructType(). Does not do
1661 // any caching, does not add any fields to the struct. This can be done later
1662 // with set_members_of_composite_type().
1663 fn create_struct_stub(cx: &CrateContext,
1664                       struct_llvm_type: Type,
1665                       struct_type_name: &str,
1666                       unique_type_id: UniqueTypeId,
1667                       containing_scope: DIScope)
1668                    -> DICompositeType {
1669     let (struct_size, struct_align) = size_and_align_of(cx, struct_llvm_type);
1670
1671     let unique_type_id_str = debug_context(cx).type_map
1672                                               .borrow()
1673                                               .get_unique_type_id_as_string(unique_type_id);
1674     let name = CString::new(struct_type_name).unwrap();
1675     let unique_type_id = CString::new(unique_type_id_str.as_bytes()).unwrap();
1676     let metadata_stub = unsafe {
1677         // LLVMRustDIBuilderCreateStructType() wants an empty array. A null
1678         // pointer will lead to hard to trace and debug LLVM assertions
1679         // later on in llvm/lib/IR/Value.cpp.
1680         let empty_array = create_DIArray(DIB(cx), &[]);
1681
1682         llvm::LLVMRustDIBuilderCreateStructType(
1683             DIB(cx),
1684             containing_scope,
1685             name.as_ptr(),
1686             unknown_file_metadata(cx),
1687             UNKNOWN_LINE_NUMBER,
1688             bytes_to_bits(struct_size),
1689             bytes_to_bits(struct_align),
1690             0,
1691             ptr::null_mut(),
1692             empty_array,
1693             0,
1694             ptr::null_mut(),
1695             unique_type_id.as_ptr())
1696     };
1697
1698     return metadata_stub;
1699 }
1700
1701 fn create_union_stub(cx: &CrateContext,
1702                      union_llvm_type: Type,
1703                      union_type_name: &str,
1704                      unique_type_id: UniqueTypeId,
1705                      containing_scope: DIScope)
1706                    -> DICompositeType {
1707     let (union_size, union_align) = size_and_align_of(cx, union_llvm_type);
1708
1709     let unique_type_id_str = debug_context(cx).type_map
1710                                               .borrow()
1711                                               .get_unique_type_id_as_string(unique_type_id);
1712     let name = CString::new(union_type_name).unwrap();
1713     let unique_type_id = CString::new(unique_type_id_str.as_bytes()).unwrap();
1714     let metadata_stub = unsafe {
1715         // LLVMRustDIBuilderCreateUnionType() wants an empty array. A null
1716         // pointer will lead to hard to trace and debug LLVM assertions
1717         // later on in llvm/lib/IR/Value.cpp.
1718         let empty_array = create_DIArray(DIB(cx), &[]);
1719
1720         llvm::LLVMRustDIBuilderCreateUnionType(
1721             DIB(cx),
1722             containing_scope,
1723             name.as_ptr(),
1724             unknown_file_metadata(cx),
1725             UNKNOWN_LINE_NUMBER,
1726             bytes_to_bits(union_size),
1727             bytes_to_bits(union_align),
1728             0, // Flags
1729             empty_array,
1730             0, // RuntimeLang
1731             unique_type_id.as_ptr())
1732     };
1733
1734     return metadata_stub;
1735 }
1736
1737 /// Creates debug information for the given global variable.
1738 ///
1739 /// Adds the created metadata nodes directly to the crate's IR.
1740 pub fn create_global_var_metadata(cx: &CrateContext,
1741                                   node_id: ast::NodeId,
1742                                   global: ValueRef) {
1743     if cx.dbg_cx().is_none() {
1744         return;
1745     }
1746
1747     let tcx = cx.tcx();
1748
1749     // Don't create debuginfo for globals inlined from other crates. The other
1750     // crate should already contain debuginfo for it. More importantly, the
1751     // global might not even exist in un-inlined form anywhere which would lead
1752     // to a linker errors.
1753     if tcx.map.is_inlined_node_id(node_id) {
1754         return;
1755     }
1756
1757     let node_def_id = tcx.map.local_def_id(node_id);
1758     let (var_scope, span) = get_namespace_and_span_for_item(cx, node_def_id);
1759
1760     let (file_metadata, line_number) = if span != syntax_pos::DUMMY_SP {
1761         let loc = span_start(cx, span);
1762         (file_metadata(cx, &loc.file.name, &loc.file.abs_path), loc.line as c_uint)
1763     } else {
1764         (unknown_file_metadata(cx), UNKNOWN_LINE_NUMBER)
1765     };
1766
1767     let is_local_to_unit = is_node_local_to_unit(cx, node_id);
1768     let variable_type = tcx.erase_regions(&tcx.node_id_to_type(node_id));
1769     let type_metadata = type_metadata(cx, variable_type, span);
1770     let var_name = tcx.item_name(node_def_id).to_string();
1771     let linkage_name = mangled_name_of_item(cx, node_def_id, "");
1772
1773     let var_name = CString::new(var_name).unwrap();
1774     let linkage_name = CString::new(linkage_name).unwrap();
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     }
1787 }
1788
1789 // Creates an "extension" of an existing DIScope into another file.
1790 pub fn extend_scope_to_file(ccx: &CrateContext,
1791                             scope_metadata: DIScope,
1792                             file: &syntax_pos::FileMap)
1793                             -> DILexicalBlock {
1794     let file_metadata = file_metadata(ccx, &file.name, &file.abs_path);
1795     unsafe {
1796         llvm::LLVMRustDIBuilderCreateLexicalBlockFile(
1797             DIB(ccx),
1798             scope_metadata,
1799             file_metadata)
1800     }
1801 }