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 impl<'a, 'tcx> TransItem<'tcx> {
  49
  50     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  51         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  52                   self.to_string(ccx.tcx()),
  53                   self.to_raw_string(),
  54                   ccx.codegen_unit().name());
  55
  56         // (*) This code executes in the context of a dep-node for the
  57         // entire CGU. In some cases, we introduce dep-nodes for
  58         // particular items that we are translating (these nodes will
  59         // have read edges coming into the CGU node). These smaller
  60         // nodes are not needed for correctness -- we always
  61         // invalidate an entire CGU at a time -- but they enable
  62         // finer-grained testing, since you can write tests that check
  63         // that the incoming edges to a particular fn are from a
  64         // particular set.
  65
  66         match *self {
  67             TransItem::Static(node_id) => {
  68                 let def_id = ccx.tcx().map.local_def_id(node_id);
  69                 let _task = ccx.tcx().dep_graph.in_task(DepNode::TransCrateItem(def_id)); // (*)
  70                 let item = ccx.tcx().map.expect_item(node_id);
  71                 if let hir::ItemStatic(_, m, _) = item.node {
  72                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  73                         Ok(_) => { /* Cool, everything's alright. */ },
  74                         Err(err) => {
  75                             // FIXME: shouldn't this be a `span_err`?
  76                             fatal_const_eval_err(
  77                                 ccx.tcx(), &err, item.span, "static");
  78                         }
  79                     };
  80                 } else {
  81                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  82                 }
  83             }
  84             TransItem::Fn(instance) => {
  85                 let _task = ccx.tcx().dep_graph.in_task(
  86                     DepNode::TransCrateItem(instance.def)); // (*)
  87
  88                 base::trans_instance(&ccx, instance);
  89             }
  90             TransItem::DropGlue(dg) => {
  91                 glue::implement_drop_glue(&ccx, dg);
  92             }
  93         }
  94
  95         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
  96                self.to_string(ccx.tcx()),
  97                self.to_raw_string(),
  98                ccx.codegen_unit().name());
  99     }
 100
 101     pub fn predefine(&self,
 102                      ccx: &CrateContext<'a, 'tcx>,
 103                      linkage: llvm::Linkage) {
 104         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 105                self.to_string(ccx.tcx()),
 106                self.to_raw_string(),
 107                ccx.codegen_unit().name());
 108
 109         let symbol_name = ccx.symbol_map()
 110                              .get_or_compute(ccx.shared(), *self);
 111
 112         debug!("symbol {}", &symbol_name);
 113
 114         match *self {
 115             TransItem::Static(node_id) => {
 116                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 117             }
 118             TransItem::Fn(instance) => {
 119                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 120             }
 121             TransItem::DropGlue(dg) => {
 122                 TransItem::predefine_drop_glue(ccx, dg, linkage, &symbol_name);
 123             }
 124         }
 125
 126         debug!("END PREDEFINING '{} ({})' in cgu {}",
 127                self.to_string(ccx.tcx()),
 128                self.to_raw_string(),
 129                ccx.codegen_unit().name());
 130     }
 131
 132     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 133                         node_id: ast::NodeId,
 134                         linkage: llvm::Linkage,
 135                         symbol_name: &str) {
 136         let def_id = ccx.tcx().map.local_def_id(node_id);
 137         let ty = ccx.tcx().item_type(def_id);
 138         let llty = type_of::type_of(ccx, ty);
 139
 140         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 141             ccx.sess().span_fatal(ccx.tcx().map.span(node_id),
 142                 &format!("symbol `{}` is already defined", symbol_name))
 143         });
 144
 145         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 146
 147         let instance = Instance::mono(ccx.shared(), def_id);
 148         ccx.instances().borrow_mut().insert(instance, g);
 149         ccx.statics().borrow_mut().insert(g, def_id);
 150     }
 151
 152     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 153                     instance: Instance<'tcx>,
 154                     linkage: llvm::Linkage,
 155                     symbol_name: &str) {
 156         assert!(!instance.substs.needs_infer() &&
 157                 !instance.substs.has_param_types());
 158
 159         let item_ty = ccx.tcx().item_type(instance.def);
 160         let item_ty = ccx.tcx().erase_regions(&item_ty);
 161         let mono_ty = monomorphize::apply_param_substs(ccx.shared(), instance.substs, &item_ty);
 162
 163         let attrs = ccx.tcx().get_attrs(instance.def);
 164         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 165         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 166         base::set_link_section(ccx, lldecl, &attrs);
 167         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 168             linkage == llvm::Linkage::WeakODRLinkage {
 169             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 170         }
 171
 172         if let ty::TyClosure(..) = mono_ty.sty {
 173             // set an inline hint for all closures
 174             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 175         }
 176
 177         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 178
 179         ccx.instances().borrow_mut().insert(instance, lldecl);
 180     }
 181
 182     fn predefine_drop_glue(ccx: &CrateContext<'a, 'tcx>,
 183                            dg: glue::DropGlueKind<'tcx>,
 184                            linkage: llvm::Linkage,
 185                            symbol_name: &str) {
 186         let tcx = ccx.tcx();
 187         assert_eq!(dg.ty(), glue::get_drop_glue_type(ccx.shared(), dg.ty()));
 188         let t = dg.ty();
 189
 190         let sig = tcx.mk_fn_sig(iter::once(tcx.mk_mut_ptr(t)), tcx.mk_nil(), false);
 191
 192         debug!("predefine_drop_glue: sig={}", sig);
 193
 194         let fn_ty = FnType::new(ccx, Abi::Rust, &sig, &[]);
 195         let llfnty = fn_ty.llvm_type(ccx);
 196
 197         assert!(declare::get_defined_value(ccx, symbol_name).is_none());
 198         let llfn = declare::declare_cfn(ccx, symbol_name, llfnty);
 199         unsafe { llvm::LLVMRustSetLinkage(llfn, linkage) };
 200         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 201            linkage == llvm::Linkage::WeakODRLinkage {
 202             llvm::SetUniqueComdat(ccx.llmod(), llfn);
 203         }
 204         attributes::set_frame_pointer_elimination(ccx, llfn);
 205         ccx.drop_glues().borrow_mut().insert(dg, (llfn, fn_ty));
 206     }
 207
 208     pub fn compute_symbol_name(&self,
 209                                scx: &SharedCrateContext<'a, 'tcx>) -> String {
 210         match *self {
 211             TransItem::Fn(instance) => instance.symbol_name(scx),
 212             TransItem::Static(node_id) => {
 213                 let def_id = scx.tcx().map.local_def_id(node_id);
 214                 Instance::mono(scx, def_id).symbol_name(scx)
 215             }
 216             TransItem::DropGlue(dg) => {
 217                 let prefix = match dg {
 218                     DropGlueKind::Ty(_) => "drop",
 219                     DropGlueKind::TyContents(_) => "drop_contents",
 220                 };
 221                 symbol_names::exported_name_from_type_and_prefix(scx, dg.ty(), prefix)
 222             }
 223         }
 224     }
 225
 226     pub fn is_from_extern_crate(&self) -> bool {
 227         match *self {
 228             TransItem::Fn(ref instance) => !instance.def.is_local(),
 229             TransItem::DropGlue(..) |
 230             TransItem::Static(..)   => false,
 231         }
 232     }
 233
 234     /// True if the translation item should only be translated to LLVM IR if
 235     /// it is referenced somewhere (like inline functions, for example).
 236     pub fn is_instantiated_only_on_demand(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
 237         if self.explicit_linkage(tcx).is_some() {
 238             return false;
 239         }
 240
 241         match *self {
 242             TransItem::Fn(ref instance) => {
 243                 !instance.def.is_local() ||
 244                 instance.substs.types().next().is_some() ||
 245                 common::is_closure(tcx, instance.def) ||
 246                 attr::requests_inline(&tcx.get_attrs(instance.def)[..])
 247             }
 248             TransItem::DropGlue(..) => true,
 249             TransItem::Static(..)   => false,
 250         }
 251     }
 252
 253     pub fn is_generic_fn(&self) -> bool {
 254         match *self {
 255             TransItem::Fn(ref instance) => {
 256                 instance.substs.types().next().is_some()
 257             }
 258             TransItem::DropGlue(..) |
 259             TransItem::Static(..)   => false,
 260         }
 261     }
 262
 263     /// Returns true if there has to be a local copy of this TransItem in every
 264     /// codegen unit that references it (as with inlined functions, for example)
 265     pub fn needs_local_copy(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
 266         // Currently everything that is instantiated only on demand is done so
 267         // with "internal" linkage, so we need a copy to be present in every
 268         // codegen unit.
 269         // This is coincidental: We could also instantiate something only if it
 270         // is referenced (e.g. a regular, private function) but place it in its
 271         // own codegen unit with "external" linkage.
 272         self.is_instantiated_only_on_demand(tcx)
 273     }
 274
 275     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 276         let def_id = match *self {
 277             TransItem::Fn(ref instance) => instance.def,
 278             TransItem::Static(node_id) => tcx.map.local_def_id(node_id),
 279             TransItem::DropGlue(..) => return None,
 280         };
 281
 282         let attributes = tcx.get_attrs(def_id);
 283         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 284             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 285                 Some(linkage)
 286             } else {
 287                 let span = tcx.map.span_if_local(def_id);
 288                 if let Some(span) = span {
 289                     tcx.sess.span_fatal(span, "invalid linkage specified")
 290                 } else {
 291                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 292                 }
 293             }
 294         } else {
 295             None
 296         }
 297     }
 298
 299     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 300         let hir_map = &tcx.map;
 301
 302         return match *self {
 303             TransItem::DropGlue(dg) => {
 304                 let mut s = String::with_capacity(32);
 305                 match dg {
 306                     DropGlueKind::Ty(_) => s.push_str("drop-glue "),
 307                     DropGlueKind::TyContents(_) => s.push_str("drop-glue-contents "),
 308                 };
 309                 let printer = DefPathBasedNames::new(tcx, false, false);
 310                 printer.push_type_name(dg.ty(), &mut s);
 311                 s
 312             }
 313             TransItem::Fn(instance) => {
 314                 to_string_internal(tcx, "fn ", instance)
 315             },
 316             TransItem::Static(node_id) => {
 317                 let def_id = hir_map.local_def_id(node_id);
 318                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 319                 to_string_internal(tcx, "static ", instance)
 320             },
 321         };
 322
 323         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 324                                         prefix: &str,
 325                                         instance: Instance<'tcx>)
 326                                         -> String {
 327             let mut result = String::with_capacity(32);
 328             result.push_str(prefix);
 329             let printer = DefPathBasedNames::new(tcx, false, false);
 330             printer.push_instance_as_string(instance, &mut result);
 331             result
 332         }
 333     }
 334
 335     pub fn to_raw_string(&self) -> String {
 336         match *self {
 337             TransItem::DropGlue(dg) => {
 338                 let prefix = match dg {
 339                     DropGlueKind::Ty(_) => "Ty",
 340                     DropGlueKind::TyContents(_) => "TyContents",
 341                 };
 342                 format!("DropGlue({}: {})", prefix, dg.ty() as *const _ as usize)
 343             }
 344             TransItem::Fn(instance) => {
 345                 format!("Fn({:?}, {})",
 346                          instance.def,
 347                          instance.substs.as_ptr() as usize)
 348             }
 349             TransItem::Static(id) => {
 350                 format!("Static({:?})", id)
 351             }
 352         }
 353     }
 354 }
 355
 356
 357 //=-----------------------------------------------------------------------------
 358 // TransItem String Keys
 359 //=-----------------------------------------------------------------------------
 360
 361 // The code below allows for producing a unique string key for a trans item.
 362 // These keys are used by the handwritten auto-tests, so they need to be
 363 // predictable and human-readable.
 364 //
 365 // Note: A lot of this could looks very similar to what's already in the
 366 //       ppaux module. It would be good to refactor things so we only have one
 367 //       parameterizable implementation for printing types.
 368
 369 /// Same as `unique_type_name()` but with the result pushed onto the given
 370 /// `output` parameter.
 371 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 372     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 373     omit_disambiguators: bool,
 374     omit_local_crate_name: bool,
 375 }
 376
 377 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 378     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 379                omit_disambiguators: bool,
 380                omit_local_crate_name: bool)
 381                -> Self {
 382         DefPathBasedNames {
 383             tcx: tcx,
 384             omit_disambiguators: omit_disambiguators,
 385             omit_local_crate_name: omit_local_crate_name,
 386         }
 387     }
 388
 389     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 390         match t.sty {
 391             ty::TyBool              => output.push_str("bool"),
 392             ty::TyChar              => output.push_str("char"),
 393             ty::TyStr               => output.push_str("str"),
 394             ty::TyNever             => output.push_str("!"),
 395             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 396             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 397             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 398             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 399             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 400             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 401             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 402             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 403             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 404             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 405             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 406             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 407             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 408             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 409             ty::TyAdt(adt_def, substs) => {
 410                 self.push_def_path(adt_def.did, output);
 411                 self.push_type_params(substs, iter::empty(), output);
 412             },
 413             ty::TyTuple(component_types) => {
 414                 output.push('(');
 415                 for &component_type in component_types {
 416                     self.push_type_name(component_type, output);
 417                     output.push_str(", ");
 418                 }
 419                 if !component_types.is_empty() {
 420                     output.pop();
 421                     output.pop();
 422                 }
 423                 output.push(')');
 424             },
 425             ty::TyBox(inner_type) => {
 426                 output.push_str("Box<");
 427                 self.push_type_name(inner_type, output);
 428                 output.push('>');
 429             },
 430             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 431                 output.push('*');
 432                 match mutbl {
 433                     hir::MutImmutable => output.push_str("const "),
 434                     hir::MutMutable => output.push_str("mut "),
 435                 }
 436
 437                 self.push_type_name(inner_type, output);
 438             },
 439             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 440                 output.push('&');
 441                 if mutbl == hir::MutMutable {
 442                     output.push_str("mut ");
 443                 }
 444
 445                 self.push_type_name(inner_type, output);
 446             },
 447             ty::TyArray(inner_type, len) => {
 448                 output.push('[');
 449                 self.push_type_name(inner_type, output);
 450                 write!(output, "; {}", len).unwrap();
 451                 output.push(']');
 452             },
 453             ty::TySlice(inner_type) => {
 454                 output.push('[');
 455                 self.push_type_name(inner_type, output);
 456                 output.push(']');
 457             },
 458             ty::TyDynamic(ref trait_data, ..) => {
 459                 if let Some(principal) = trait_data.principal() {
 460                     self.push_def_path(principal.def_id(), output);
 461                     self.push_type_params(principal.skip_binder().substs,
 462                         trait_data.projection_bounds(),
 463                         output);
 464                 }
 465             },
 466             ty::TyFnDef(.., &ty::BareFnTy{ unsafety, abi, ref sig } ) |
 467             ty::TyFnPtr(&ty::BareFnTy{ unsafety, abi, ref sig } ) => {
 468                 if unsafety == hir::Unsafety::Unsafe {
 469                     output.push_str("unsafe ");
 470                 }
 471
 472                 if abi != ::abi::Abi::Rust {
 473                     output.push_str("extern \"");
 474                     output.push_str(abi.name());
 475                     output.push_str("\" ");
 476                 }
 477
 478                 output.push_str("fn(");
 479
 480                 let sig = self.tcx.erase_late_bound_regions_and_normalize(sig);
 481
 482                 if !sig.inputs().is_empty() {
 483                     for &parameter_type in sig.inputs() {
 484                         self.push_type_name(parameter_type, output);
 485                         output.push_str(", ");
 486                     }
 487                     output.pop();
 488                     output.pop();
 489                 }
 490
 491                 if sig.variadic {
 492                     if !sig.inputs().is_empty() {
 493                         output.push_str(", ...");
 494                     } else {
 495                         output.push_str("...");
 496                     }
 497                 }
 498
 499                 output.push(')');
 500
 501                 if !sig.output().is_nil() {
 502                     output.push_str(" -> ");
 503                     self.push_type_name(sig.output(), output);
 504                 }
 505             },
 506             ty::TyClosure(def_id, ref closure_substs) => {
 507                 self.push_def_path(def_id, output);
 508                 let generics = self.tcx.item_generics(self.tcx.closure_base_def_id(def_id));
 509                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 510                 self.push_type_params(substs, iter::empty(), output);
 511             }
 512             ty::TyError |
 513             ty::TyInfer(_) |
 514             ty::TyProjection(..) |
 515             ty::TyParam(_) |
 516             ty::TyAnon(..) => {
 517                 bug!("DefPathBasedNames: Trying to create type name for \
 518                                          unexpected type: {:?}", t);
 519             }
 520         }
 521     }
 522
 523     pub fn push_def_path(&self,
 524                          def_id: DefId,
 525                          output: &mut String) {
 526         let def_path = self.tcx.def_path(def_id);
 527
 528         // some_crate::
 529         if !(self.omit_local_crate_name && def_id.is_local()) {
 530             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 531             output.push_str("::");
 532         }
 533
 534         // foo::bar::ItemName::
 535         for part in self.tcx.def_path(def_id).data {
 536             if self.omit_disambiguators {
 537                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 538             } else {
 539                 write!(output, "{}[{}]::",
 540                        part.data.as_interned_str(),
 541                        part.disambiguator).unwrap();
 542             }
 543         }
 544
 545         // remove final "::"
 546         output.pop();
 547         output.pop();
 548     }
 549
 550     fn push_type_params<I>(&self,
 551                             substs: &Substs<'tcx>,
 552                             projections: I,
 553                             output: &mut String)
 554         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 555     {
 556         let mut projections = projections.peekable();
 557         if substs.types().next().is_none() && projections.peek().is_none() {
 558             return;
 559         }
 560
 561         output.push('<');
 562
 563         for type_parameter in substs.types() {
 564             self.push_type_name(type_parameter, output);
 565             output.push_str(", ");
 566         }
 567
 568         for projection in projections {
 569             let projection = projection.skip_binder();
 570             let name = &projection.item_name.as_str();
 571             output.push_str(name);
 572             output.push_str("=");
 573             self.push_type_name(projection.ty, output);
 574             output.push_str(", ");
 575         }
 576
 577         output.pop();
 578         output.pop();
 579
 580         output.push('>');
 581     }
 582
 583     pub fn push_instance_as_string(&self,
 584                                    instance: Instance<'tcx>,
 585                                    output: &mut String) {
 586         self.push_def_path(instance.def, output);
 587         self.push_type_params(instance.substs, iter::empty(), output);
 588     }
 589 }