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 common;
  22 use declare;
  23 use glue::DropGlueKind;
  24 use llvm;
  25 use monomorphize::{self, 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 rustc_const_eval::fatal_const_eval_err;
  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 use std::fmt::Write;
  39 use std::iter;
  40
  41 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  42 pub enum TransItem<'tcx> {
  43     DropGlue(DropGlueKind<'tcx>),
  44     Fn(Instance<'tcx>),
  45     Static(NodeId)
  46 }
  47
  48 /// Describes how a translation item will be instantiated in object files.
  49 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  50 pub enum InstantiationMode {
  51     /// There will be exactly one instance of the given TransItem. It will have
  52     /// external linkage so that it can be linked to from other codegen units.
  53     GloballyShared,
  54
  55     /// Each codegen unit containing a reference to the given TransItem will
  56     /// have its own private copy of the function (with internal linkage).
  57     LocalCopy,
  58 }
  59
  60 impl<'a, 'tcx> TransItem<'tcx> {
  61
  62     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  63         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  64                   self.to_string(ccx.tcx()),
  65                   self.to_raw_string(),
  66                   ccx.codegen_unit().name());
  67
  68         // (*) This code executes in the context of a dep-node for the
  69         // entire CGU. In some cases, we introduce dep-nodes for
  70         // particular items that we are translating (these nodes will
  71         // have read edges coming into the CGU node). These smaller
  72         // nodes are not needed for correctness -- we always
  73         // invalidate an entire CGU at a time -- but they enable
  74         // finer-grained testing, since you can write tests that check
  75         // that the incoming edges to a particular fn are from a
  76         // particular set.
  77
  78         match *self {
  79             TransItem::Static(node_id) => {
  80                 let def_id = ccx.tcx().hir.local_def_id(node_id);
  81                 let _task = ccx.tcx().dep_graph.in_task(DepNode::TransCrateItem(def_id)); // (*)
  82                 let item = ccx.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                             // FIXME: shouldn't this be a `span_err`?
  88                             fatal_const_eval_err(
  89                                 ccx.tcx(), &err, item.span, "static");
  90                         }
  91                     };
  92                 } else {
  93                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  94                 }
  95             }
  96             TransItem::Fn(instance) => {
  97                 let _task = ccx.tcx().dep_graph.in_task(
  98                     DepNode::TransCrateItem(instance.def)); // (*)
  99
 100                 base::trans_instance(&ccx, instance);
 101             }
 102             TransItem::DropGlue(dg) => {
 103                 glue::implement_drop_glue(&ccx, dg);
 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::DropGlue(dg) => {
 134                 TransItem::predefine_drop_glue(ccx, dg, linkage, &symbol_name);
 135             }
 136         }
 137
 138         debug!("END PREDEFINING '{} ({})' in cgu {}",
 139                self.to_string(ccx.tcx()),
 140                self.to_raw_string(),
 141                ccx.codegen_unit().name());
 142     }
 143
 144     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 145                         node_id: ast::NodeId,
 146                         linkage: llvm::Linkage,
 147                         symbol_name: &str) {
 148         let def_id = ccx.tcx().hir.local_def_id(node_id);
 149         let ty = ccx.tcx().item_type(def_id);
 150         let llty = type_of::type_of(ccx, ty);
 151
 152         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 153             ccx.sess().span_fatal(ccx.tcx().hir.span(node_id),
 154                 &format!("symbol `{}` is already defined", symbol_name))
 155         });
 156
 157         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 158
 159         let instance = Instance::mono(ccx.shared(), def_id);
 160         ccx.instances().borrow_mut().insert(instance, g);
 161         ccx.statics().borrow_mut().insert(g, def_id);
 162     }
 163
 164     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 165                     instance: Instance<'tcx>,
 166                     linkage: llvm::Linkage,
 167                     symbol_name: &str) {
 168         assert!(!instance.substs.needs_infer() &&
 169                 !instance.substs.has_param_types());
 170
 171         let item_ty = ccx.tcx().item_type(instance.def);
 172         let item_ty = ccx.tcx().erase_regions(&item_ty);
 173         let mono_ty = monomorphize::apply_param_substs(ccx.shared(), instance.substs, &item_ty);
 174
 175         let attrs = ccx.tcx().get_attrs(instance.def);
 176         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 177         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 178         base::set_link_section(ccx, lldecl, &attrs);
 179         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 180             linkage == llvm::Linkage::WeakODRLinkage {
 181             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 182         }
 183
 184         if let ty::TyClosure(..) = mono_ty.sty {
 185             // set an inline hint for all closures
 186             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 187         }
 188
 189         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 190
 191         ccx.instances().borrow_mut().insert(instance, lldecl);
 192     }
 193
 194     fn predefine_drop_glue(ccx: &CrateContext<'a, 'tcx>,
 195                            dg: glue::DropGlueKind<'tcx>,
 196                            linkage: llvm::Linkage,
 197                            symbol_name: &str) {
 198         let tcx = ccx.tcx();
 199         assert_eq!(dg.ty(), glue::get_drop_glue_type(ccx.shared(), dg.ty()));
 200         let t = dg.ty();
 201
 202         let sig = tcx.mk_fn_sig(iter::once(tcx.mk_mut_ptr(t)), tcx.mk_nil(), false);
 203
 204         debug!("predefine_drop_glue: sig={}", sig);
 205
 206         let fn_ty = FnType::new(ccx, Abi::Rust, &sig, &[]);
 207         let llfnty = fn_ty.llvm_type(ccx);
 208
 209         assert!(declare::get_defined_value(ccx, symbol_name).is_none());
 210         let llfn = declare::declare_cfn(ccx, symbol_name, llfnty);
 211         unsafe { llvm::LLVMRustSetLinkage(llfn, linkage) };
 212         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 213            linkage == llvm::Linkage::WeakODRLinkage {
 214             llvm::SetUniqueComdat(ccx.llmod(), llfn);
 215         }
 216         attributes::set_frame_pointer_elimination(ccx, llfn);
 217         ccx.drop_glues().borrow_mut().insert(dg, (llfn, fn_ty));
 218     }
 219
 220     pub fn compute_symbol_name(&self,
 221                                scx: &SharedCrateContext<'a, 'tcx>) -> String {
 222         match *self {
 223             TransItem::Fn(instance) => instance.symbol_name(scx),
 224             TransItem::Static(node_id) => {
 225                 let def_id = scx.tcx().hir.local_def_id(node_id);
 226                 Instance::mono(scx, def_id).symbol_name(scx)
 227             }
 228             TransItem::DropGlue(dg) => {
 229                 let prefix = match dg {
 230                     DropGlueKind::Ty(_) => "drop",
 231                     DropGlueKind::TyContents(_) => "drop_contents",
 232                 };
 233                 symbol_names::exported_name_from_type_and_prefix(scx, dg.ty(), prefix)
 234             }
 235         }
 236     }
 237
 238     pub fn is_from_extern_crate(&self) -> bool {
 239         match *self {
 240             TransItem::Fn(ref instance) => !instance.def.is_local(),
 241             TransItem::DropGlue(..) |
 242             TransItem::Static(..)   => false,
 243         }
 244     }
 245
 246     pub fn instantiation_mode(&self,
 247                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 248                               -> InstantiationMode {
 249         match *self {
 250             TransItem::Fn(ref instance) => {
 251                 if self.explicit_linkage(tcx).is_none() &&
 252                    (common::is_closure(tcx, instance.def) ||
 253                     attr::requests_inline(&tcx.get_attrs(instance.def)[..])) {
 254                     InstantiationMode::LocalCopy
 255                 } else {
 256                     InstantiationMode::GloballyShared
 257                 }
 258             }
 259             TransItem::DropGlue(..) => InstantiationMode::LocalCopy,
 260             TransItem::Static(..) => InstantiationMode::GloballyShared,
 261         }
 262     }
 263
 264     pub fn is_generic_fn(&self) -> bool {
 265         match *self {
 266             TransItem::Fn(ref instance) => {
 267                 instance.substs.types().next().is_some()
 268             }
 269             TransItem::DropGlue(..) |
 270             TransItem::Static(..)   => false,
 271         }
 272     }
 273
 274     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 275         let def_id = match *self {
 276             TransItem::Fn(ref instance) => instance.def,
 277             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 278             TransItem::DropGlue(..) => return None,
 279         };
 280
 281         let attributes = tcx.get_attrs(def_id);
 282         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 283             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 284                 Some(linkage)
 285             } else {
 286                 let span = tcx.hir.span_if_local(def_id);
 287                 if let Some(span) = span {
 288                     tcx.sess.span_fatal(span, "invalid linkage specified")
 289                 } else {
 290                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 291                 }
 292             }
 293         } else {
 294             None
 295         }
 296     }
 297
 298     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 299         let hir_map = &tcx.hir;
 300
 301         return match *self {
 302             TransItem::DropGlue(dg) => {
 303                 let mut s = String::with_capacity(32);
 304                 match dg {
 305                     DropGlueKind::Ty(_) => s.push_str("drop-glue "),
 306                     DropGlueKind::TyContents(_) => s.push_str("drop-glue-contents "),
 307                 };
 308                 let printer = DefPathBasedNames::new(tcx, false, false);
 309                 printer.push_type_name(dg.ty(), &mut s);
 310                 s
 311             }
 312             TransItem::Fn(instance) => {
 313                 to_string_internal(tcx, "fn ", instance)
 314             },
 315             TransItem::Static(node_id) => {
 316                 let def_id = hir_map.local_def_id(node_id);
 317                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 318                 to_string_internal(tcx, "static ", instance)
 319             },
 320         };
 321
 322         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 323                                         prefix: &str,
 324                                         instance: Instance<'tcx>)
 325                                         -> String {
 326             let mut result = String::with_capacity(32);
 327             result.push_str(prefix);
 328             let printer = DefPathBasedNames::new(tcx, false, false);
 329             printer.push_instance_as_string(instance, &mut result);
 330             result
 331         }
 332     }
 333
 334     pub fn to_raw_string(&self) -> String {
 335         match *self {
 336             TransItem::DropGlue(dg) => {
 337                 let prefix = match dg {
 338                     DropGlueKind::Ty(_) => "Ty",
 339                     DropGlueKind::TyContents(_) => "TyContents",
 340                 };
 341                 format!("DropGlue({}: {})", prefix, dg.ty() as *const _ as usize)
 342             }
 343             TransItem::Fn(instance) => {
 344                 format!("Fn({:?}, {})",
 345                          instance.def,
 346                          instance.substs.as_ptr() as usize)
 347             }
 348             TransItem::Static(id) => {
 349                 format!("Static({:?})", id)
 350             }
 351         }
 352     }
 353 }
 354
 355
 356 //=-----------------------------------------------------------------------------
 357 // TransItem String Keys
 358 //=-----------------------------------------------------------------------------
 359
 360 // The code below allows for producing a unique string key for a trans item.
 361 // These keys are used by the handwritten auto-tests, so they need to be
 362 // predictable and human-readable.
 363 //
 364 // Note: A lot of this could looks very similar to what's already in the
 365 //       ppaux module. It would be good to refactor things so we only have one
 366 //       parameterizable implementation for printing types.
 367
 368 /// Same as `unique_type_name()` but with the result pushed onto the given
 369 /// `output` parameter.
 370 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 371     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 372     omit_disambiguators: bool,
 373     omit_local_crate_name: bool,
 374 }
 375
 376 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 377     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 378                omit_disambiguators: bool,
 379                omit_local_crate_name: bool)
 380                -> Self {
 381         DefPathBasedNames {
 382             tcx: tcx,
 383             omit_disambiguators: omit_disambiguators,
 384             omit_local_crate_name: omit_local_crate_name,
 385         }
 386     }
 387
 388     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 389         match t.sty {
 390             ty::TyBool              => output.push_str("bool"),
 391             ty::TyChar              => output.push_str("char"),
 392             ty::TyStr               => output.push_str("str"),
 393             ty::TyNever             => output.push_str("!"),
 394             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 395             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 396             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 397             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 398             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 399             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 400             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 401             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 402             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 403             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 404             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 405             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 406             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 407             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 408             ty::TyAdt(adt_def, substs) => {
 409                 self.push_def_path(adt_def.did, output);
 410                 self.push_type_params(substs, iter::empty(), output);
 411             },
 412             ty::TyTuple(component_types, _) => {
 413                 output.push('(');
 414                 for &component_type in component_types {
 415                     self.push_type_name(component_type, output);
 416                     output.push_str(", ");
 417                 }
 418                 if !component_types.is_empty() {
 419                     output.pop();
 420                     output.pop();
 421                 }
 422                 output.push(')');
 423             },
 424             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 425                 output.push('*');
 426                 match mutbl {
 427                     hir::MutImmutable => output.push_str("const "),
 428                     hir::MutMutable => output.push_str("mut "),
 429                 }
 430
 431                 self.push_type_name(inner_type, output);
 432             },
 433             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 434                 output.push('&');
 435                 if mutbl == hir::MutMutable {
 436                     output.push_str("mut ");
 437                 }
 438
 439                 self.push_type_name(inner_type, output);
 440             },
 441             ty::TyArray(inner_type, len) => {
 442                 output.push('[');
 443                 self.push_type_name(inner_type, output);
 444                 write!(output, "; {}", len).unwrap();
 445                 output.push(']');
 446             },
 447             ty::TySlice(inner_type) => {
 448                 output.push('[');
 449                 self.push_type_name(inner_type, output);
 450                 output.push(']');
 451             },
 452             ty::TyDynamic(ref trait_data, ..) => {
 453                 if let Some(principal) = trait_data.principal() {
 454                     self.push_def_path(principal.def_id(), output);
 455                     self.push_type_params(principal.skip_binder().substs,
 456                         trait_data.projection_bounds(),
 457                         output);
 458                 }
 459             },
 460             ty::TyFnDef(.., &ty::BareFnTy{ unsafety, abi, ref sig } ) |
 461             ty::TyFnPtr(&ty::BareFnTy{ unsafety, abi, ref sig } ) => {
 462                 if unsafety == hir::Unsafety::Unsafe {
 463                     output.push_str("unsafe ");
 464                 }
 465
 466                 if abi != ::abi::Abi::Rust {
 467                     output.push_str("extern \"");
 468                     output.push_str(abi.name());
 469                     output.push_str("\" ");
 470                 }
 471
 472                 output.push_str("fn(");
 473
 474                 let sig = self.tcx.erase_late_bound_regions_and_normalize(sig);
 475
 476                 if !sig.inputs().is_empty() {
 477                     for &parameter_type in sig.inputs() {
 478                         self.push_type_name(parameter_type, output);
 479                         output.push_str(", ");
 480                     }
 481                     output.pop();
 482                     output.pop();
 483                 }
 484
 485                 if sig.variadic {
 486                     if !sig.inputs().is_empty() {
 487                         output.push_str(", ...");
 488                     } else {
 489                         output.push_str("...");
 490                     }
 491                 }
 492
 493                 output.push(')');
 494
 495                 if !sig.output().is_nil() {
 496                     output.push_str(" -> ");
 497                     self.push_type_name(sig.output(), output);
 498                 }
 499             },
 500             ty::TyClosure(def_id, ref closure_substs) => {
 501                 self.push_def_path(def_id, output);
 502                 let generics = self.tcx.item_generics(self.tcx.closure_base_def_id(def_id));
 503                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 504                 self.push_type_params(substs, iter::empty(), output);
 505             }
 506             ty::TyError |
 507             ty::TyInfer(_) |
 508             ty::TyProjection(..) |
 509             ty::TyParam(_) |
 510             ty::TyAnon(..) => {
 511                 bug!("DefPathBasedNames: Trying to create type name for \
 512                                          unexpected type: {:?}", t);
 513             }
 514         }
 515     }
 516
 517     pub fn push_def_path(&self,
 518                          def_id: DefId,
 519                          output: &mut String) {
 520         let def_path = self.tcx.def_path(def_id);
 521
 522         // some_crate::
 523         if !(self.omit_local_crate_name && def_id.is_local()) {
 524             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 525             output.push_str("::");
 526         }
 527
 528         // foo::bar::ItemName::
 529         for part in self.tcx.def_path(def_id).data {
 530             if self.omit_disambiguators {
 531                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 532             } else {
 533                 write!(output, "{}[{}]::",
 534                        part.data.as_interned_str(),
 535                        part.disambiguator).unwrap();
 536             }
 537         }
 538
 539         // remove final "::"
 540         output.pop();
 541         output.pop();
 542     }
 543
 544     fn push_type_params<I>(&self,
 545                             substs: &Substs<'tcx>,
 546                             projections: I,
 547                             output: &mut String)
 548         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 549     {
 550         let mut projections = projections.peekable();
 551         if substs.types().next().is_none() && projections.peek().is_none() {
 552             return;
 553         }
 554
 555         output.push('<');
 556
 557         for type_parameter in substs.types() {
 558             self.push_type_name(type_parameter, output);
 559             output.push_str(", ");
 560         }
 561
 562         for projection in projections {
 563             let projection = projection.skip_binder();
 564             let name = &projection.item_name.as_str();
 565             output.push_str(name);
 566             output.push_str("=");
 567             self.push_type_name(projection.ty, output);
 568             output.push_str(", ");
 569         }
 570
 571         output.pop();
 572         output.pop();
 573
 574         output.push('>');
 575     }
 576
 577     pub fn push_instance_as_string(&self,
 578                                    instance: Instance<'tcx>,
 579                                    output: &mut String) {
 580         self.push_def_path(instance.def, output);
 581         self.push_type_params(instance.substs, iter::empty(), output);
 582     }
 583 }