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 asm;
  18 use attributes;
  19 use base;
  20 use consts;
  21 use context::CrateContext;
  22 use common;
  23 use declare;
  24 use llvm;
  25 use monomorphize::Instance;
  26 use rustc::hir;
  27 use rustc::hir::def_id::DefId;
  28 use rustc::traits;
  29 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  30 use rustc::ty::subst::{Subst, Substs};
  31 use syntax::ast::{self, NodeId};
  32 use syntax::attr;
  33 use syntax_pos::Span;
  34 use syntax_pos::symbol::Symbol;
  35 use type_of;
  36 use std::fmt::Write;
  37 use std::iter;
  38
  39 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  40 pub enum TransItem<'tcx> {
  41     Fn(Instance<'tcx>),
  42     Static(NodeId),
  43     GlobalAsm(NodeId),
  44 }
  45
  46 /// Describes how a translation item will be instantiated in object files.
  47 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  48 pub enum InstantiationMode {
  49     /// There will be exactly one instance of the given TransItem. It will have
  50     /// external linkage so that it can be linked to from other codegen units.
  51     GloballyShared,
  52
  53     /// Each codegen unit containing a reference to the given TransItem will
  54     /// have its own private copy of the function (with internal linkage).
  55     LocalCopy,
  56 }
  57
  58 impl<'a, 'tcx> TransItem<'tcx> {
  59
  60     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  61         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  62                   self.to_string(ccx.tcx()),
  63                   self.to_raw_string(),
  64                   ccx.codegen_unit().name());
  65
  66         match *self {
  67             TransItem::Static(node_id) => {
  68                 let tcx = ccx.tcx();
  69                 let item = tcx.hir.expect_item(node_id);
  70                 if let hir::ItemStatic(_, m, _) = item.node {
  71                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  72                         Ok(_) => { /* Cool, everything's alright. */ },
  73                         Err(err) => {
  74                             err.report(tcx, item.span, "static");
  75                         }
  76                     };
  77                 } else {
  78                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  79                 }
  80             }
  81             TransItem::GlobalAsm(node_id) => {
  82                 let item = ccx.tcx().hir.expect_item(node_id);
  83                 if let hir::ItemGlobalAsm(ref ga) = item.node {
  84                     asm::trans_global_asm(ccx, ga);
  85                 } else {
  86                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  87                 }
  88             }
  89             TransItem::Fn(instance) => {
  90                 base::trans_instance(&ccx, instance);
  91             }
  92         }
  93
  94         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
  95                self.to_string(ccx.tcx()),
  96                self.to_raw_string(),
  97                ccx.codegen_unit().name());
  98     }
  99
 100     pub fn predefine(&self,
 101                      ccx: &CrateContext<'a, 'tcx>,
 102                      linkage: llvm::Linkage) {
 103         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 104                self.to_string(ccx.tcx()),
 105                self.to_raw_string(),
 106                ccx.codegen_unit().name());
 107
 108         let symbol_name = self.symbol_name(ccx.tcx());
 109
 110         debug!("symbol {}", &symbol_name);
 111
 112         match *self {
 113             TransItem::Static(node_id) => {
 114                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 115             }
 116             TransItem::Fn(instance) => {
 117                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 118             }
 119             TransItem::GlobalAsm(..) => {}
 120         }
 121
 122         debug!("END PREDEFINING '{} ({})' in cgu {}",
 123                self.to_string(ccx.tcx()),
 124                self.to_raw_string(),
 125                ccx.codegen_unit().name());
 126     }
 127
 128     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 129                         node_id: ast::NodeId,
 130                         linkage: llvm::Linkage,
 131                         symbol_name: &str) {
 132         let def_id = ccx.tcx().hir.local_def_id(node_id);
 133         let instance = Instance::mono(ccx.tcx(), def_id);
 134         let ty = common::instance_ty(ccx.shared(), &instance);
 135         let llty = type_of::type_of(ccx, ty);
 136
 137         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 138             ccx.sess().span_fatal(ccx.tcx().hir.span(node_id),
 139                 &format!("symbol `{}` is already defined", symbol_name))
 140         });
 141
 142         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 143
 144         ccx.instances().borrow_mut().insert(instance, g);
 145         ccx.statics().borrow_mut().insert(g, def_id);
 146     }
 147
 148     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 149                     instance: Instance<'tcx>,
 150                     linkage: llvm::Linkage,
 151                     symbol_name: &str) {
 152         assert!(!instance.substs.needs_infer() &&
 153                 !instance.substs.has_param_types());
 154
 155         let mono_ty = common::instance_ty(ccx.shared(), &instance);
 156         let attrs = instance.def.attrs(ccx.tcx());
 157         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 158         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 159         base::set_link_section(ccx, lldecl, &attrs);
 160         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 161             linkage == llvm::Linkage::WeakODRLinkage {
 162             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 163         }
 164
 165         debug!("predefine_fn: mono_ty = {:?} instance = {:?}", mono_ty, instance);
 166         if common::is_inline_instance(ccx.tcx(), &instance) {
 167             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 168         }
 169         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 170
 171         ccx.instances().borrow_mut().insert(instance, lldecl);
 172     }
 173
 174     pub fn symbol_name(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> ty::SymbolName {
 175         match *self {
 176             TransItem::Fn(instance) => tcx.symbol_name(instance),
 177             TransItem::Static(node_id) => {
 178                 let def_id = tcx.hir.local_def_id(node_id);
 179                 tcx.symbol_name(Instance::mono(tcx, def_id))
 180             }
 181             TransItem::GlobalAsm(node_id) => {
 182                 let def_id = tcx.hir.local_def_id(node_id);
 183                 ty::SymbolName {
 184                     name: Symbol::intern(&format!("global_asm_{:?}", def_id)).as_str()
 185                 }
 186             }
 187         }
 188     }
 189
 190     pub fn local_span(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Span> {
 191         match *self {
 192             TransItem::Fn(Instance { def, .. }) => {
 193                 tcx.hir.as_local_node_id(def.def_id())
 194             }
 195             TransItem::Static(node_id) |
 196             TransItem::GlobalAsm(node_id) => {
 197                 Some(node_id)
 198             }
 199         }.map(|node_id| tcx.hir.span(node_id))
 200     }
 201
 202     pub fn instantiation_mode(&self,
 203                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 204                               -> InstantiationMode {
 205         match *self {
 206             TransItem::Fn(ref instance) => {
 207                 if self.explicit_linkage(tcx).is_none() &&
 208                     common::requests_inline(tcx, instance)
 209                 {
 210                     InstantiationMode::LocalCopy
 211                 } else {
 212                     InstantiationMode::GloballyShared
 213                 }
 214             }
 215             TransItem::Static(..) => InstantiationMode::GloballyShared,
 216             TransItem::GlobalAsm(..) => InstantiationMode::GloballyShared,
 217         }
 218     }
 219
 220     pub fn is_generic_fn(&self) -> bool {
 221         match *self {
 222             TransItem::Fn(ref instance) => {
 223                 instance.substs.types().next().is_some()
 224             }
 225             TransItem::Static(..) |
 226             TransItem::GlobalAsm(..) => false,
 227         }
 228     }
 229
 230     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 231         let def_id = match *self {
 232             TransItem::Fn(ref instance) => instance.def_id(),
 233             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 234             TransItem::GlobalAsm(..) => return None,
 235         };
 236
 237         let attributes = tcx.get_attrs(def_id);
 238         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 239             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 240                 Some(linkage)
 241             } else {
 242                 let span = tcx.hir.span_if_local(def_id);
 243                 if let Some(span) = span {
 244                     tcx.sess.span_fatal(span, "invalid linkage specified")
 245                 } else {
 246                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 247                 }
 248             }
 249         } else {
 250             None
 251         }
 252     }
 253
 254     /// Returns whether this instance is instantiable - whether it has no unsatisfied
 255     /// predicates.
 256     pub fn is_instantiable(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
 257         debug!("is_instantiable({:?})", self);
 258         let (def_id, substs) = match *self {
 259             TransItem::Fn(ref instance) => (instance.def_id(), instance.substs),
 260             TransItem::Static(node_id) => (tcx.hir.local_def_id(node_id), Substs::empty()),
 261             // global asm never has predicates
 262             TransItem::GlobalAsm(..) => return true
 263         };
 264
 265         let predicates = tcx.predicates_of(def_id).predicates.subst(tcx, substs);
 266         traits::normalize_and_test_predicates(tcx, predicates)
 267     }
 268
 269     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 270         let hir_map = &tcx.hir;
 271
 272         return match *self {
 273             TransItem::Fn(instance) => {
 274                 to_string_internal(tcx, "fn ", instance)
 275             },
 276             TransItem::Static(node_id) => {
 277                 let def_id = hir_map.local_def_id(node_id);
 278                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 279                 to_string_internal(tcx, "static ", instance)
 280             },
 281             TransItem::GlobalAsm(..) => {
 282                 "global_asm".to_string()
 283             }
 284         };
 285
 286         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 287                                         prefix: &str,
 288                                         instance: Instance<'tcx>)
 289                                         -> String {
 290             let mut result = String::with_capacity(32);
 291             result.push_str(prefix);
 292             let printer = DefPathBasedNames::new(tcx, false, false);
 293             printer.push_instance_as_string(instance, &mut result);
 294             result
 295         }
 296     }
 297
 298     pub fn to_raw_string(&self) -> String {
 299         match *self {
 300             TransItem::Fn(instance) => {
 301                 format!("Fn({:?}, {})",
 302                          instance.def,
 303                          instance.substs.as_ptr() as usize)
 304             }
 305             TransItem::Static(id) => {
 306                 format!("Static({:?})", id)
 307             }
 308             TransItem::GlobalAsm(id) => {
 309                 format!("GlobalAsm({:?})", id)
 310             }
 311         }
 312     }
 313 }
 314
 315
 316 //=-----------------------------------------------------------------------------
 317 // TransItem String Keys
 318 //=-----------------------------------------------------------------------------
 319
 320 // The code below allows for producing a unique string key for a trans item.
 321 // These keys are used by the handwritten auto-tests, so they need to be
 322 // predictable and human-readable.
 323 //
 324 // Note: A lot of this could looks very similar to what's already in the
 325 //       ppaux module. It would be good to refactor things so we only have one
 326 //       parameterizable implementation for printing types.
 327
 328 /// Same as `unique_type_name()` but with the result pushed onto the given
 329 /// `output` parameter.
 330 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 331     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 332     omit_disambiguators: bool,
 333     omit_local_crate_name: bool,
 334 }
 335
 336 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 337     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 338                omit_disambiguators: bool,
 339                omit_local_crate_name: bool)
 340                -> Self {
 341         DefPathBasedNames {
 342             tcx: tcx,
 343             omit_disambiguators: omit_disambiguators,
 344             omit_local_crate_name: omit_local_crate_name,
 345         }
 346     }
 347
 348     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 349         match t.sty {
 350             ty::TyBool              => output.push_str("bool"),
 351             ty::TyChar              => output.push_str("char"),
 352             ty::TyStr               => output.push_str("str"),
 353             ty::TyNever             => output.push_str("!"),
 354             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 355             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 356             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 357             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 358             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 359             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 360             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 361             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 362             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 363             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 364             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 365             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 366             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 367             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 368             ty::TyAdt(adt_def, substs) => {
 369                 self.push_def_path(adt_def.did, output);
 370                 self.push_type_params(substs, iter::empty(), output);
 371             },
 372             ty::TyTuple(component_types, _) => {
 373                 output.push('(');
 374                 for &component_type in component_types {
 375                     self.push_type_name(component_type, output);
 376                     output.push_str(", ");
 377                 }
 378                 if !component_types.is_empty() {
 379                     output.pop();
 380                     output.pop();
 381                 }
 382                 output.push(')');
 383             },
 384             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 385                 output.push('*');
 386                 match mutbl {
 387                     hir::MutImmutable => output.push_str("const "),
 388                     hir::MutMutable => output.push_str("mut "),
 389                 }
 390
 391                 self.push_type_name(inner_type, output);
 392             },
 393             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 394                 output.push('&');
 395                 if mutbl == hir::MutMutable {
 396                     output.push_str("mut ");
 397                 }
 398
 399                 self.push_type_name(inner_type, output);
 400             },
 401             ty::TyArray(inner_type, len) => {
 402                 output.push('[');
 403                 self.push_type_name(inner_type, output);
 404                 write!(output, "; {}", len).unwrap();
 405                 output.push(']');
 406             },
 407             ty::TySlice(inner_type) => {
 408                 output.push('[');
 409                 self.push_type_name(inner_type, output);
 410                 output.push(']');
 411             },
 412             ty::TyDynamic(ref trait_data, ..) => {
 413                 if let Some(principal) = trait_data.principal() {
 414                     self.push_def_path(principal.def_id(), output);
 415                     self.push_type_params(principal.skip_binder().substs,
 416                         trait_data.projection_bounds(),
 417                         output);
 418                 }
 419             },
 420             ty::TyFnDef(.., sig) |
 421             ty::TyFnPtr(sig) => {
 422                 if sig.unsafety() == hir::Unsafety::Unsafe {
 423                     output.push_str("unsafe ");
 424                 }
 425
 426                 let abi = sig.abi();
 427                 if abi != ::abi::Abi::Rust {
 428                     output.push_str("extern \"");
 429                     output.push_str(abi.name());
 430                     output.push_str("\" ");
 431                 }
 432
 433                 output.push_str("fn(");
 434
 435                 let sig = self.tcx.erase_late_bound_regions_and_normalize(&sig);
 436
 437                 if !sig.inputs().is_empty() {
 438                     for &parameter_type in sig.inputs() {
 439                         self.push_type_name(parameter_type, output);
 440                         output.push_str(", ");
 441                     }
 442                     output.pop();
 443                     output.pop();
 444                 }
 445
 446                 if sig.variadic {
 447                     if !sig.inputs().is_empty() {
 448                         output.push_str(", ...");
 449                     } else {
 450                         output.push_str("...");
 451                     }
 452                 }
 453
 454                 output.push(')');
 455
 456                 if !sig.output().is_nil() {
 457                     output.push_str(" -> ");
 458                     self.push_type_name(sig.output(), output);
 459                 }
 460             },
 461             ty::TyClosure(def_id, ref closure_substs) => {
 462                 self.push_def_path(def_id, output);
 463                 let generics = self.tcx.generics_of(self.tcx.closure_base_def_id(def_id));
 464                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 465                 self.push_type_params(substs, iter::empty(), output);
 466             }
 467             ty::TyError |
 468             ty::TyInfer(_) |
 469             ty::TyProjection(..) |
 470             ty::TyParam(_) |
 471             ty::TyAnon(..) => {
 472                 bug!("DefPathBasedNames: Trying to create type name for \
 473                                          unexpected type: {:?}", t);
 474             }
 475         }
 476     }
 477
 478     pub fn push_def_path(&self,
 479                          def_id: DefId,
 480                          output: &mut String) {
 481         let def_path = self.tcx.def_path(def_id);
 482
 483         // some_crate::
 484         if !(self.omit_local_crate_name && def_id.is_local()) {
 485             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 486             output.push_str("::");
 487         }
 488
 489         // foo::bar::ItemName::
 490         for part in self.tcx.def_path(def_id).data {
 491             if self.omit_disambiguators {
 492                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 493             } else {
 494                 write!(output, "{}[{}]::",
 495                        part.data.as_interned_str(),
 496                        part.disambiguator).unwrap();
 497             }
 498         }
 499
 500         // remove final "::"
 501         output.pop();
 502         output.pop();
 503     }
 504
 505     fn push_type_params<I>(&self,
 506                             substs: &Substs<'tcx>,
 507                             projections: I,
 508                             output: &mut String)
 509         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 510     {
 511         let mut projections = projections.peekable();
 512         if substs.types().next().is_none() && projections.peek().is_none() {
 513             return;
 514         }
 515
 516         output.push('<');
 517
 518         for type_parameter in substs.types() {
 519             self.push_type_name(type_parameter, output);
 520             output.push_str(", ");
 521         }
 522
 523         for projection in projections {
 524             let projection = projection.skip_binder();
 525             let name = &projection.item_name.as_str();
 526             output.push_str(name);
 527             output.push_str("=");
 528             self.push_type_name(projection.ty, output);
 529             output.push_str(", ");
 530         }
 531
 532         output.pop();
 533         output.pop();
 534
 535         output.push('>');
 536     }
 537
 538     pub fn push_instance_as_string(&self,
 539                                    instance: Instance<'tcx>,
 540                                    output: &mut String) {
 541         self.push_def_path(instance.def_id(), output);
 542         self.push_type_params(instance.substs, iter::empty(), output);
 543     }
 544 }