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