src/librustc_trans/trans_item.rs

   1 // Copyright 2016 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 //! Walks the crate looking for items/impl-items/trait-items that have
  12 //! either a `rustc_symbol_name` or `rustc_item_path` attribute and
  13 //! generates an error giving, respectively, the symbol name or
  14 //! item-path. This is used for unit testing the code that generates
  15 //! paths etc in all kinds of annoying scenarios.
  16
  17 use attributes;
  18 use base;
  19 use consts;
  20 use context::{CrateContext, SharedCrateContext};
  21 use declare;
  22 use glue::DropGlueKind;
  23 use llvm;
  24 use monomorphize::{self, Instance};
  25 use rustc::dep_graph::DepNode;
  26 use rustc::hir;
  27 use rustc::hir::def_id::DefId;
  28 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  29 use rustc::ty::subst::Substs;
  30 use rustc_const_eval::fatal_const_eval_err;
  31 use std::hash::{Hash, Hasher};
  32 use syntax::ast::{self, NodeId};
  33 use syntax::attr;
  34 use type_of;
  35 use glue;
  36 use abi::{Abi, FnType};
  37 use back::symbol_names;
  38
  39 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
  40 pub enum TransItem<'tcx> {
  41     DropGlue(DropGlueKind<'tcx>),
  42     Fn(Instance<'tcx>),
  43     Static(NodeId)
  44 }
  45
  46 impl<'tcx> Hash for TransItem<'tcx> {
  47     fn hash<H: Hasher>(&self, s: &mut H) {
  48         match *self {
  49             TransItem::DropGlue(t) => {
  50                 0u8.hash(s);
  51                 t.hash(s);
  52             },
  53             TransItem::Fn(instance) => {
  54                 1u8.hash(s);
  55                 instance.def.hash(s);
  56                 (instance.substs as *const _ as usize).hash(s);
  57             }
  58             TransItem::Static(node_id) => {
  59                 2u8.hash(s);
  60                 node_id.hash(s);
  61             }
  62         };
  63     }
  64 }
  65
  66 impl<'a, 'tcx> TransItem<'tcx> {
  67
  68     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  69         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  70                   self.to_string(ccx.tcx()),
  71                   self.to_raw_string(),
  72                   ccx.codegen_unit().name());
  73
  74         // (*) This code executes in the context of a dep-node for the
  75         // entire CGU. In some cases, we introduce dep-nodes for
  76         // particular items that we are translating (these nodes will
  77         // have read edges coming into the CGU node). These smaller
  78         // nodes are not needed for correctness -- we always
  79         // invalidate an entire CGU at a time -- but they enable
  80         // finer-grained testing, since you can write tests that check
  81         // that the incoming edges to a particular fn are from a
  82         // particular set.
  83
  84         match *self {
  85             TransItem::Static(node_id) => {
  86                 let def_id = ccx.tcx().map.local_def_id(node_id);
  87                 let _task = ccx.tcx().dep_graph.in_task(DepNode::TransCrateItem(def_id)); // (*)
  88                 let item = ccx.tcx().map.expect_item(node_id);
  89                 if let hir::ItemStatic(_, m, _) = item.node {
  90                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  91                         Ok(_) => { /* Cool, everything's alright. */ },
  92                         Err(err) => {
  93                             // FIXME: shouldn't this be a `span_err`?
  94                             fatal_const_eval_err(
  95                                 ccx.tcx(), &err, item.span, "static");
  96                         }
  97                     };
  98                 } else {
  99                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
 100                 }
 101             }
 102             TransItem::Fn(instance) => {
 103                 let _task = ccx.tcx().dep_graph.in_task(
 104                     DepNode::TransCrateItem(instance.def)); // (*)
 105
 106                 base::trans_instance(&ccx, instance);
 107             }
 108             TransItem::DropGlue(dg) => {
 109                 glue::implement_drop_glue(&ccx, dg);
 110             }
 111         }
 112
 113         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
 114                self.to_string(ccx.tcx()),
 115                self.to_raw_string(),
 116                ccx.codegen_unit().name());
 117     }
 118
 119     pub fn predefine(&self,
 120                      ccx: &CrateContext<'a, 'tcx>,
 121                      linkage: llvm::Linkage) {
 122         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 123                self.to_string(ccx.tcx()),
 124                self.to_raw_string(),
 125                ccx.codegen_unit().name());
 126
 127         let symbol_name = ccx.symbol_map()
 128                              .get_or_compute(ccx.shared(), *self);
 129
 130         debug!("symbol {}", &symbol_name);
 131
 132         match *self {
 133             TransItem::Static(node_id) => {
 134                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 135             }
 136             TransItem::Fn(instance) => {
 137                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 138             }
 139             TransItem::DropGlue(dg) => {
 140                 TransItem::predefine_drop_glue(ccx, dg, linkage, &symbol_name);
 141             }
 142         }
 143
 144         debug!("END PREDEFINING '{} ({})' in cgu {}",
 145                self.to_string(ccx.tcx()),
 146                self.to_raw_string(),
 147                ccx.codegen_unit().name());
 148     }
 149
 150     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 151                         node_id: ast::NodeId,
 152                         linkage: llvm::Linkage,
 153                         symbol_name: &str) {
 154         let def_id = ccx.tcx().map.local_def_id(node_id);
 155         let ty = ccx.tcx().lookup_item_type(def_id).ty;
 156         let llty = type_of::type_of(ccx, ty);
 157
 158         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 159             ccx.sess().span_fatal(ccx.tcx().map.span(node_id),
 160                 &format!("symbol `{}` is already defined", symbol_name))
 161         });
 162
 163         unsafe { llvm::LLVMSetLinkage(g, linkage) };
 164
 165         let instance = Instance::mono(ccx.shared(), def_id);
 166         ccx.instances().borrow_mut().insert(instance, g);
 167         ccx.statics().borrow_mut().insert(g, def_id);
 168     }
 169
 170     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 171                     instance: Instance<'tcx>,
 172                     linkage: llvm::Linkage,
 173                     symbol_name: &str) {
 174         assert!(!instance.substs.types.needs_infer() &&
 175                 !instance.substs.types.has_param_types());
 176
 177         let item_ty = ccx.tcx().lookup_item_type(instance.def).ty;
 178         let item_ty = ccx.tcx().erase_regions(&item_ty);
 179         let mono_ty = monomorphize::apply_param_substs(ccx.tcx(), instance.substs, &item_ty);
 180
 181         let attrs = ccx.tcx().get_attrs(instance.def);
 182         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 183         unsafe { llvm::LLVMSetLinkage(lldecl, linkage) };
 184         base::set_link_section(ccx, lldecl, &attrs);
 185         if linkage == llvm::LinkOnceODRLinkage ||
 186             linkage == llvm::WeakODRLinkage {
 187             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 188         }
 189
 190         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 191
 192         ccx.instances().borrow_mut().insert(instance, lldecl);
 193     }
 194
 195     fn predefine_drop_glue(ccx: &CrateContext<'a, 'tcx>,
 196                            dg: glue::DropGlueKind<'tcx>,
 197                            linkage: llvm::Linkage,
 198                            symbol_name: &str) {
 199         let tcx = ccx.tcx();
 200         assert_eq!(dg.ty(), glue::get_drop_glue_type(tcx, dg.ty()));
 201         let t = dg.ty();
 202
 203         let sig = ty::FnSig {
 204             inputs: vec![tcx.mk_mut_ptr(tcx.types.i8)],
 205             output: tcx.mk_nil(),
 206             variadic: false,
 207         };
 208
 209         // Create a FnType for fn(*mut i8) and substitute the real type in
 210         // later - that prevents FnType from splitting fat pointers up.
 211         let mut fn_ty = FnType::new(ccx, Abi::Rust, &sig, &[]);
 212         fn_ty.args[0].original_ty = type_of::type_of(ccx, t).ptr_to();
 213         let llfnty = fn_ty.llvm_type(ccx);
 214
 215         assert!(declare::get_defined_value(ccx, symbol_name).is_none());
 216         let llfn = declare::declare_cfn(ccx, symbol_name, llfnty);
 217         unsafe { llvm::LLVMSetLinkage(llfn, linkage) };
 218         if linkage == llvm::LinkOnceODRLinkage ||
 219            linkage == llvm::WeakODRLinkage {
 220             llvm::SetUniqueComdat(ccx.llmod(), llfn);
 221         }
 222         attributes::set_frame_pointer_elimination(ccx, llfn);
 223         ccx.drop_glues().borrow_mut().insert(dg, (llfn, fn_ty));
 224     }
 225
 226     pub fn compute_symbol_name(&self,
 227                                scx: &SharedCrateContext<'a, 'tcx>) -> String {
 228         match *self {
 229             TransItem::Fn(instance) => instance.symbol_name(scx),
 230             TransItem::Static(node_id) => {
 231                 let def_id = scx.tcx().map.local_def_id(node_id);
 232                 Instance::mono(scx, def_id).symbol_name(scx)
 233             }
 234             TransItem::DropGlue(dg) => {
 235                 let prefix = match dg {
 236                     DropGlueKind::Ty(_) => "drop",
 237                     DropGlueKind::TyContents(_) => "drop_contents",
 238                 };
 239                 symbol_names::exported_name_from_type_and_prefix(scx, dg.ty(), prefix)
 240             }
 241         }
 242     }
 243
 244     pub fn requests_inline(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
 245         match *self {
 246             TransItem::Fn(ref instance) => {
 247                 !instance.substs.types.is_empty() || {
 248                     let attributes = tcx.get_attrs(instance.def);
 249                     attr::requests_inline(&attributes[..])
 250                 }
 251             }
 252             TransItem::DropGlue(..) => true,
 253             TransItem::Static(..)   => false,
 254         }
 255     }
 256
 257     pub fn is_from_extern_crate(&self) -> bool {
 258         match *self {
 259             TransItem::Fn(ref instance) => !instance.def.is_local(),
 260             TransItem::DropGlue(..) |
 261             TransItem::Static(..)   => false,
 262         }
 263     }
 264
 265     pub fn is_instantiated_only_on_demand(&self) -> bool {
 266         match *self {
 267             TransItem::Fn(ref instance) => !instance.def.is_local() ||
 268                                            !instance.substs.types.is_empty(),
 269             TransItem::DropGlue(..) => true,
 270             TransItem::Static(..)   => false,
 271         }
 272     }
 273
 274     pub fn is_generic_fn(&self) -> bool {
 275         match *self {
 276             TransItem::Fn(ref instance) => !instance.substs.types.is_empty(),
 277             TransItem::DropGlue(..) |
 278             TransItem::Static(..)   => false,
 279         }
 280     }
 281
 282     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 283         let def_id = match *self {
 284             TransItem::Fn(ref instance) => instance.def,
 285             TransItem::Static(node_id) => tcx.map.local_def_id(node_id),
 286             TransItem::DropGlue(..) => return None,
 287         };
 288
 289         let attributes = tcx.get_attrs(def_id);
 290         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 291             if let Some(linkage) = base::llvm_linkage_by_name(&name) {
 292                 Some(linkage)
 293             } else {
 294                 let span = tcx.map.span_if_local(def_id);
 295                 if let Some(span) = span {
 296                     tcx.sess.span_fatal(span, "invalid linkage specified")
 297                 } else {
 298                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 299                 }
 300             }
 301         } else {
 302             None
 303         }
 304     }
 305
 306     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 307         let hir_map = &tcx.map;
 308
 309         return match *self {
 310             TransItem::DropGlue(dg) => {
 311                 let mut s = String::with_capacity(32);
 312                 match dg {
 313                     DropGlueKind::Ty(_) => s.push_str("drop-glue "),
 314                     DropGlueKind::TyContents(_) => s.push_str("drop-glue-contents "),
 315                 };
 316                 push_unique_type_name(tcx, dg.ty(), &mut s);
 317                 s
 318             }
 319             TransItem::Fn(instance) => {
 320                 to_string_internal(tcx, "fn ", instance)
 321             },
 322             TransItem::Static(node_id) => {
 323                 let def_id = hir_map.local_def_id(node_id);
 324                 let instance = Instance::new(def_id, Substs::empty(tcx));
 325                 to_string_internal(tcx, "static ", instance)
 326             },
 327         };
 328
 329         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 330                                         prefix: &str,
 331                                         instance: Instance<'tcx>)
 332                                         -> String {
 333             let mut result = String::with_capacity(32);
 334             result.push_str(prefix);
 335             push_instance_as_string(tcx, instance, &mut result);
 336             result
 337         }
 338     }
 339
 340     pub fn to_raw_string(&self) -> String {
 341         match *self {
 342             TransItem::DropGlue(dg) => {
 343                 let prefix = match dg {
 344                     DropGlueKind::Ty(_) => "Ty",
 345                     DropGlueKind::TyContents(_) => "TyContents",
 346                 };
 347                 format!("DropGlue({}: {})", prefix, dg.ty() as *const _ as usize)
 348             }
 349             TransItem::Fn(instance) => {
 350                 format!("Fn({:?}, {})",
 351                          instance.def,
 352                          instance.substs as *const _ as usize)
 353             }
 354             TransItem::Static(id) => {
 355                 format!("Static({:?})", id)
 356             }
 357         }
 358     }
 359 }
 360
 361
 362 //=-----------------------------------------------------------------------------
 363 // TransItem String Keys
 364 //=-----------------------------------------------------------------------------
 365
 366 // The code below allows for producing a unique string key for a trans item.
 367 // These keys are used by the handwritten auto-tests, so they need to be
 368 // predictable and human-readable.
 369 //
 370 // Note: A lot of this could looks very similar to what's already in the
 371 //       ppaux module. It would be good to refactor things so we only have one
 372 //       parameterizable implementation for printing types.
 373
 374 /// Same as `unique_type_name()` but with the result pushed onto the given
 375 /// `output` parameter.
 376 pub fn push_unique_type_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 377                                        t: ty::Ty<'tcx>,
 378                                        output: &mut String) {
 379     match t.sty {
 380         ty::TyBool              => output.push_str("bool"),
 381         ty::TyChar              => output.push_str("char"),
 382         ty::TyStr               => output.push_str("str"),
 383         ty::TyNever             => output.push_str("!"),
 384         ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 385         ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 386         ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 387         ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 388         ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 389         ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 390         ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 391         ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 392         ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 393         ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 394         ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 395         ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 396         ty::TyStruct(adt_def, substs) |
 397         ty::TyEnum(adt_def, substs) => {
 398             push_item_name(tcx, adt_def.did, output);
 399             push_type_params(tcx, &substs.types, &[], output);
 400         },
 401         ty::TyTuple(component_types) => {
 402             output.push('(');
 403             for &component_type in component_types {
 404                 push_unique_type_name(tcx, component_type, output);
 405                 output.push_str(", ");
 406             }
 407             if !component_types.is_empty() {
 408                 output.pop();
 409                 output.pop();
 410             }
 411             output.push(')');
 412         },
 413         ty::TyBox(inner_type) => {
 414             output.push_str("Box<");
 415             push_unique_type_name(tcx, inner_type, output);
 416             output.push('>');
 417         },
 418         ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 419             output.push('*');
 420             match mutbl {
 421                 hir::MutImmutable => output.push_str("const "),
 422                 hir::MutMutable => output.push_str("mut "),
 423             }
 424
 425             push_unique_type_name(tcx, inner_type, output);
 426         },
 427         ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 428             output.push('&');
 429             if mutbl == hir::MutMutable {
 430                 output.push_str("mut ");
 431             }
 432
 433             push_unique_type_name(tcx, inner_type, output);
 434         },
 435         ty::TyArray(inner_type, len) => {
 436             output.push('[');
 437             push_unique_type_name(tcx, inner_type, output);
 438             output.push_str(&format!("; {}", len));
 439             output.push(']');
 440         },
 441         ty::TySlice(inner_type) => {
 442             output.push('[');
 443             push_unique_type_name(tcx, inner_type, output);
 444             output.push(']');
 445         },
 446         ty::TyTrait(ref trait_data) => {
 447             push_item_name(tcx, trait_data.principal.def_id(), output);
 448             push_type_params(tcx,
 449                              &trait_data.principal.skip_binder().substs.types,
 450                              &trait_data.projection_bounds,
 451                              output);
 452         },
 453         ty::TyFnDef(_, _, &ty::BareFnTy{ unsafety, abi, ref sig } ) |
 454         ty::TyFnPtr(&ty::BareFnTy{ unsafety, abi, ref sig } ) => {
 455             if unsafety == hir::Unsafety::Unsafe {
 456                 output.push_str("unsafe ");
 457             }
 458
 459             if abi != ::abi::Abi::Rust {
 460                 output.push_str("extern \"");
 461                 output.push_str(abi.name());
 462                 output.push_str("\" ");
 463             }
 464
 465             output.push_str("fn(");
 466
 467             let sig = tcx.erase_late_bound_regions(sig);
 468             if !sig.inputs.is_empty() {
 469                 for &parameter_type in &sig.inputs {
 470                     push_unique_type_name(tcx, parameter_type, output);
 471                     output.push_str(", ");
 472                 }
 473                 output.pop();
 474                 output.pop();
 475             }
 476
 477             if sig.variadic {
 478                 if !sig.inputs.is_empty() {
 479                     output.push_str(", ...");
 480                 } else {
 481                     output.push_str("...");
 482                 }
 483             }
 484
 485             output.push(')');
 486
 487             if !sig.output.is_nil() {
 488                 output.push_str(" -> ");
 489                 push_unique_type_name(tcx, sig.output, output);
 490             }
 491         },
 492         ty::TyClosure(def_id, ref closure_substs) => {
 493             push_item_name(tcx, def_id, output);
 494             output.push_str("{");
 495             output.push_str(&format!("{}:{}", def_id.krate, def_id.index.as_usize()));
 496             output.push_str("}");
 497             push_type_params(tcx, &closure_substs.func_substs.types, &[], output);
 498         }
 499         ty::TyError |
 500         ty::TyInfer(_) |
 501         ty::TyProjection(..) |
 502         ty::TyParam(_) |
 503         ty::TyAnon(..) => {
 504             bug!("debuginfo: Trying to create type name for \
 505                   unexpected type: {:?}", t);
 506         }
 507     }
 508 }
 509
 510 fn push_item_name(tcx: TyCtxt,
 511                   def_id: DefId,
 512                   output: &mut String) {
 513     let def_path = tcx.def_path(def_id);
 514
 515     // some_crate::
 516     output.push_str(&tcx.crate_name(def_path.krate));
 517     output.push_str("::");
 518
 519     // foo::bar::ItemName::
 520     for part in tcx.def_path(def_id).data {
 521         output.push_str(&format!("{}[{}]::",
 522                         part.data.as_interned_str(),
 523                         part.disambiguator));
 524     }
 525
 526     // remove final "::"
 527     output.pop();
 528     output.pop();
 529 }
 530
 531 fn push_type_params<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 532                               types: &[Ty<'tcx>],
 533                               projections: &[ty::PolyExistentialProjection<'tcx>],
 534                               output: &mut String) {
 535     if types.is_empty() && projections.is_empty() {
 536         return;
 537     }
 538
 539     output.push('<');
 540
 541     for &type_parameter in types {
 542         push_unique_type_name(tcx, type_parameter, output);
 543         output.push_str(", ");
 544     }
 545
 546     for projection in projections {
 547         let projection = projection.skip_binder();
 548         let name = &projection.item_name.as_str();
 549         output.push_str(name);
 550         output.push_str("=");
 551         push_unique_type_name(tcx, projection.ty, output);
 552         output.push_str(", ");
 553     }
 554
 555     output.pop();
 556     output.pop();
 557
 558     output.push('>');
 559 }
 560
 561 fn push_instance_as_string<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 562                                      instance: Instance<'tcx>,
 563                                      output: &mut String) {
 564     push_item_name(tcx, instance.def, output);
 565     push_type_params(tcx, &instance.substs.types, &[], output);
 566 }
 567
 568 pub fn def_id_to_string(tcx: TyCtxt, def_id: DefId) -> String {
 569     let mut output = String::new();
 570     push_item_name(tcx, def_id, &mut output);
 571     output
 572 }
 573
 574 pub fn type_to_string<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 575                                 ty: ty::Ty<'tcx>)
 576                                 -> String {
 577     let mut output = String::new();
 578     push_unique_type_name(tcx, ty, &mut output);
 579     output
 580 }