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::dep_graph::DepKind;
  27 use rustc::hir;
  28 use rustc::hir::def_id::DefId;
  29 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  30 use rustc::ty::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         // (*) This code executes in the context of a dep-node for the
  67         // entire CGU. In some cases, we introduce dep-nodes for
  68         // particular items that we are translating (these nodes will
  69         // have read edges coming into the CGU node). These smaller
  70         // nodes are not needed for correctness -- we always
  71         // invalidate an entire CGU at a time -- but they enable
  72         // finer-grained testing, since you can write tests that check
  73         // that the incoming edges to a particular fn are from a
  74         // particular set.
  75
  76         match *self {
  77             TransItem::Static(node_id) => {
  78                 let tcx = ccx.tcx();
  79                 let def_id = tcx.hir.local_def_id(node_id);
  80                 let dep_node = def_id.to_dep_node(tcx, DepKind::TransCrateItem);
  81                 let _task = ccx.tcx().dep_graph.in_task(dep_node); // (*)
  82                 let item = tcx.hir.expect_item(node_id);
  83                 if let hir::ItemStatic(_, m, _) = item.node {
  84                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  85                         Ok(_) => { /* Cool, everything's alright. */ },
  86                         Err(err) => {
  87                             err.report(tcx, item.span, "static");
  88                         }
  89                     };
  90                 } else {
  91                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  92                 }
  93             }
  94             TransItem::GlobalAsm(node_id) => {
  95                 let item = ccx.tcx().hir.expect_item(node_id);
  96                 if let hir::ItemGlobalAsm(ref ga) = item.node {
  97                     asm::trans_global_asm(ccx, ga);
  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                     instance.def_id()
 105                             .to_dep_node(ccx.tcx(), DepKind::TransCrateItem)); // (*)
 106
 107                 base::trans_instance(&ccx, instance);
 108             }
 109         }
 110
 111         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
 112                self.to_string(ccx.tcx()),
 113                self.to_raw_string(),
 114                ccx.codegen_unit().name());
 115     }
 116
 117     pub fn predefine(&self,
 118                      ccx: &CrateContext<'a, 'tcx>,
 119                      linkage: llvm::Linkage) {
 120         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 121                self.to_string(ccx.tcx()),
 122                self.to_raw_string(),
 123                ccx.codegen_unit().name());
 124
 125         let symbol_name = self.symbol_name(ccx.tcx());
 126
 127         debug!("symbol {}", &symbol_name);
 128
 129         match *self {
 130             TransItem::Static(node_id) => {
 131                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 132             }
 133             TransItem::Fn(instance) => {
 134                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 135             }
 136             TransItem::GlobalAsm(..) => {}
 137         }
 138
 139         debug!("END PREDEFINING '{} ({})' in cgu {}",
 140                self.to_string(ccx.tcx()),
 141                self.to_raw_string(),
 142                ccx.codegen_unit().name());
 143     }
 144
 145     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 146                         node_id: ast::NodeId,
 147                         linkage: llvm::Linkage,
 148                         symbol_name: &str) {
 149         let def_id = ccx.tcx().hir.local_def_id(node_id);
 150         let instance = Instance::mono(ccx.tcx(), def_id);
 151         let ty = common::instance_ty(ccx.shared(), &instance);
 152         let llty = type_of::type_of(ccx, ty);
 153
 154         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 155             ccx.sess().span_fatal(ccx.tcx().hir.span(node_id),
 156                 &format!("symbol `{}` is already defined", symbol_name))
 157         });
 158
 159         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 160
 161         ccx.instances().borrow_mut().insert(instance, g);
 162         ccx.statics().borrow_mut().insert(g, def_id);
 163     }
 164
 165     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 166                     instance: Instance<'tcx>,
 167                     linkage: llvm::Linkage,
 168                     symbol_name: &str) {
 169         assert!(!instance.substs.needs_infer() &&
 170                 !instance.substs.has_param_types());
 171
 172         let mono_ty = common::instance_ty(ccx.shared(), &instance);
 173         let attrs = instance.def.attrs(ccx.tcx());
 174         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 175         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 176         base::set_link_section(ccx, lldecl, &attrs);
 177         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 178             linkage == llvm::Linkage::WeakODRLinkage {
 179             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 180         }
 181
 182         debug!("predefine_fn: mono_ty = {:?} instance = {:?}", mono_ty, instance);
 183         if common::is_inline_instance(ccx.tcx(), &instance) {
 184             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 185         }
 186         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 187
 188         ccx.instances().borrow_mut().insert(instance, lldecl);
 189     }
 190
 191     pub fn symbol_name(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> ty::SymbolName {
 192         match *self {
 193             TransItem::Fn(instance) => tcx.symbol_name(instance),
 194             TransItem::Static(node_id) => {
 195                 let def_id = tcx.hir.local_def_id(node_id);
 196                 tcx.symbol_name(Instance::mono(tcx, def_id))
 197             }
 198             TransItem::GlobalAsm(node_id) => {
 199                 let def_id = tcx.hir.local_def_id(node_id);
 200                 ty::SymbolName {
 201                     name: Symbol::intern(&format!("global_asm_{:?}", def_id)).as_str()
 202                 }
 203             }
 204         }
 205     }
 206
 207     pub fn local_span(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<Span> {
 208         match *self {
 209             TransItem::Fn(Instance { def, .. }) => {
 210                 tcx.hir.as_local_node_id(def.def_id())
 211             }
 212             TransItem::Static(node_id) |
 213             TransItem::GlobalAsm(node_id) => {
 214                 Some(node_id)
 215             }
 216         }.map(|node_id| tcx.hir.span(node_id))
 217     }
 218
 219     pub fn instantiation_mode(&self,
 220                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 221                               -> InstantiationMode {
 222         match *self {
 223             TransItem::Fn(ref instance) => {
 224                 if self.explicit_linkage(tcx).is_none() &&
 225                     common::requests_inline(tcx, instance)
 226                 {
 227                     InstantiationMode::LocalCopy
 228                 } else {
 229                     InstantiationMode::GloballyShared
 230                 }
 231             }
 232             TransItem::Static(..) => InstantiationMode::GloballyShared,
 233             TransItem::GlobalAsm(..) => InstantiationMode::GloballyShared,
 234         }
 235     }
 236
 237     pub fn is_generic_fn(&self) -> bool {
 238         match *self {
 239             TransItem::Fn(ref instance) => {
 240                 instance.substs.types().next().is_some()
 241             }
 242             TransItem::Static(..) |
 243             TransItem::GlobalAsm(..) => false,
 244         }
 245     }
 246
 247     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 248         let def_id = match *self {
 249             TransItem::Fn(ref instance) => instance.def_id(),
 250             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 251             TransItem::GlobalAsm(..) => return None,
 252         };
 253
 254         let attributes = tcx.get_attrs(def_id);
 255         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 256             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 257                 Some(linkage)
 258             } else {
 259                 let span = tcx.hir.span_if_local(def_id);
 260                 if let Some(span) = span {
 261                     tcx.sess.span_fatal(span, "invalid linkage specified")
 262                 } else {
 263                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 264                 }
 265             }
 266         } else {
 267             None
 268         }
 269     }
 270
 271     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 272         let hir_map = &tcx.hir;
 273
 274         return match *self {
 275             TransItem::Fn(instance) => {
 276                 to_string_internal(tcx, "fn ", instance)
 277             },
 278             TransItem::Static(node_id) => {
 279                 let def_id = hir_map.local_def_id(node_id);
 280                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 281                 to_string_internal(tcx, "static ", instance)
 282             },
 283             TransItem::GlobalAsm(..) => {
 284                 "global_asm".to_string()
 285             }
 286         };
 287
 288         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 289                                         prefix: &str,
 290                                         instance: Instance<'tcx>)
 291                                         -> String {
 292             let mut result = String::with_capacity(32);
 293             result.push_str(prefix);
 294             let printer = DefPathBasedNames::new(tcx, false, false);
 295             printer.push_instance_as_string(instance, &mut result);
 296             result
 297         }
 298     }
 299
 300     pub fn to_raw_string(&self) -> String {
 301         match *self {
 302             TransItem::Fn(instance) => {
 303                 format!("Fn({:?}, {})",
 304                          instance.def,
 305                          instance.substs.as_ptr() as usize)
 306             }
 307             TransItem::Static(id) => {
 308                 format!("Static({:?})", id)
 309             }
 310             TransItem::GlobalAsm(id) => {
 311                 format!("GlobalAsm({:?})", id)
 312             }
 313         }
 314     }
 315 }
 316
 317
 318 //=-----------------------------------------------------------------------------
 319 // TransItem String Keys
 320 //=-----------------------------------------------------------------------------
 321
 322 // The code below allows for producing a unique string key for a trans item.
 323 // These keys are used by the handwritten auto-tests, so they need to be
 324 // predictable and human-readable.
 325 //
 326 // Note: A lot of this could looks very similar to what's already in the
 327 //       ppaux module. It would be good to refactor things so we only have one
 328 //       parameterizable implementation for printing types.
 329
 330 /// Same as `unique_type_name()` but with the result pushed onto the given
 331 /// `output` parameter.
 332 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 333     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 334     omit_disambiguators: bool,
 335     omit_local_crate_name: bool,
 336 }
 337
 338 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 339     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 340                omit_disambiguators: bool,
 341                omit_local_crate_name: bool)
 342                -> Self {
 343         DefPathBasedNames {
 344             tcx: tcx,
 345             omit_disambiguators: omit_disambiguators,
 346             omit_local_crate_name: omit_local_crate_name,
 347         }
 348     }
 349
 350     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 351         match t.sty {
 352             ty::TyBool              => output.push_str("bool"),
 353             ty::TyChar              => output.push_str("char"),
 354             ty::TyStr               => output.push_str("str"),
 355             ty::TyNever             => output.push_str("!"),
 356             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 357             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 358             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 359             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 360             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 361             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 362             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 363             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 364             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 365             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 366             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 367             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 368             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 369             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 370             ty::TyAdt(adt_def, substs) => {
 371                 self.push_def_path(adt_def.did, output);
 372                 self.push_type_params(substs, iter::empty(), output);
 373             },
 374             ty::TyTuple(component_types, _) => {
 375                 output.push('(');
 376                 for &component_type in component_types {
 377                     self.push_type_name(component_type, output);
 378                     output.push_str(", ");
 379                 }
 380                 if !component_types.is_empty() {
 381                     output.pop();
 382                     output.pop();
 383                 }
 384                 output.push(')');
 385             },
 386             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 387                 output.push('*');
 388                 match mutbl {
 389                     hir::MutImmutable => output.push_str("const "),
 390                     hir::MutMutable => output.push_str("mut "),
 391                 }
 392
 393                 self.push_type_name(inner_type, output);
 394             },
 395             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 396                 output.push('&');
 397                 if mutbl == hir::MutMutable {
 398                     output.push_str("mut ");
 399                 }
 400
 401                 self.push_type_name(inner_type, output);
 402             },
 403             ty::TyArray(inner_type, len) => {
 404                 output.push('[');
 405                 self.push_type_name(inner_type, output);
 406                 write!(output, "; {}", len).unwrap();
 407                 output.push(']');
 408             },
 409             ty::TySlice(inner_type) => {
 410                 output.push('[');
 411                 self.push_type_name(inner_type, output);
 412                 output.push(']');
 413             },
 414             ty::TyDynamic(ref trait_data, ..) => {
 415                 if let Some(principal) = trait_data.principal() {
 416                     self.push_def_path(principal.def_id(), output);
 417                     self.push_type_params(principal.skip_binder().substs,
 418                         trait_data.projection_bounds(),
 419                         output);
 420                 }
 421             },
 422             ty::TyFnDef(.., sig) |
 423             ty::TyFnPtr(sig) => {
 424                 if sig.unsafety() == hir::Unsafety::Unsafe {
 425                     output.push_str("unsafe ");
 426                 }
 427
 428                 let abi = sig.abi();
 429                 if abi != ::abi::Abi::Rust {
 430                     output.push_str("extern \"");
 431                     output.push_str(abi.name());
 432                     output.push_str("\" ");
 433                 }
 434
 435                 output.push_str("fn(");
 436
 437                 let sig = self.tcx.erase_late_bound_regions_and_normalize(&sig);
 438
 439                 if !sig.inputs().is_empty() {
 440                     for &parameter_type in sig.inputs() {
 441                         self.push_type_name(parameter_type, output);
 442                         output.push_str(", ");
 443                     }
 444                     output.pop();
 445                     output.pop();
 446                 }
 447
 448                 if sig.variadic {
 449                     if !sig.inputs().is_empty() {
 450                         output.push_str(", ...");
 451                     } else {
 452                         output.push_str("...");
 453                     }
 454                 }
 455
 456                 output.push(')');
 457
 458                 if !sig.output().is_nil() {
 459                     output.push_str(" -> ");
 460                     self.push_type_name(sig.output(), output);
 461                 }
 462             },
 463             ty::TyClosure(def_id, ref closure_substs) => {
 464                 self.push_def_path(def_id, output);
 465                 let generics = self.tcx.generics_of(self.tcx.closure_base_def_id(def_id));
 466                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 467                 self.push_type_params(substs, iter::empty(), output);
 468             }
 469             ty::TyError |
 470             ty::TyInfer(_) |
 471             ty::TyProjection(..) |
 472             ty::TyParam(_) |
 473             ty::TyAnon(..) => {
 474                 bug!("DefPathBasedNames: Trying to create type name for \
 475                                          unexpected type: {:?}", t);
 476             }
 477         }
 478     }
 479
 480     pub fn push_def_path(&self,
 481                          def_id: DefId,
 482                          output: &mut String) {
 483         let def_path = self.tcx.def_path(def_id);
 484
 485         // some_crate::
 486         if !(self.omit_local_crate_name && def_id.is_local()) {
 487             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 488             output.push_str("::");
 489         }
 490
 491         // foo::bar::ItemName::
 492         for part in self.tcx.def_path(def_id).data {
 493             if self.omit_disambiguators {
 494                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 495             } else {
 496                 write!(output, "{}[{}]::",
 497                        part.data.as_interned_str(),
 498                        part.disambiguator).unwrap();
 499             }
 500         }
 501
 502         // remove final "::"
 503         output.pop();
 504         output.pop();
 505     }
 506
 507     fn push_type_params<I>(&self,
 508                             substs: &Substs<'tcx>,
 509                             projections: I,
 510                             output: &mut String)
 511         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 512     {
 513         let mut projections = projections.peekable();
 514         if substs.types().next().is_none() && projections.peek().is_none() {
 515             return;
 516         }
 517
 518         output.push('<');
 519
 520         for type_parameter in substs.types() {
 521             self.push_type_name(type_parameter, output);
 522             output.push_str(", ");
 523         }
 524
 525         for projection in projections {
 526             let projection = projection.skip_binder();
 527             let name = &projection.item_name.as_str();
 528             output.push_str(name);
 529             output.push_str("=");
 530             self.push_type_name(projection.ty, output);
 531             output.push_str(", ");
 532         }
 533
 534         output.pop();
 535         output.pop();
 536
 537         output.push('>');
 538     }
 539
 540     pub fn push_instance_as_string(&self,
 541                                    instance: Instance<'tcx>,
 542                                    output: &mut String) {
 543         self.push_def_path(instance.def_id(), output);
 544         self.push_type_params(instance.substs, iter::empty(), output);
 545     }
 546 }