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::Instance;
  26 use rustc::dep_graph::DepNode;
  27 use rustc::hir;
  28 use rustc::hir::def_id::DefId;
  29 use rustc::hir::map::definitions::DefPathData;
  30 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  31 use rustc::ty::subst::Substs;
  32 use rustc_const_eval::fatal_const_eval_err;
  33 use syntax::ast::{self, NodeId};
  34 use syntax::attr;
  35 use type_of;
  36 use glue;
  37 use abi::{Abi, FnType};
  38 use back::symbol_names;
  39 use std::fmt::Write;
  40 use std::iter;
  41
  42 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  43 pub enum TransItem<'tcx> {
  44     DropGlue(DropGlueKind<'tcx>),
  45     Fn(Instance<'tcx>),
  46     Static(NodeId)
  47 }
  48
  49 /// Describes how a translation item will be instantiated in object files.
  50 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  51 pub enum InstantiationMode {
  52     /// There will be exactly one instance of the given TransItem. It will have
  53     /// external linkage so that it can be linked to from other codegen units.
  54     GloballyShared,
  55
  56     /// Each codegen unit containing a reference to the given TransItem will
  57     /// have its own private copy of the function (with internal linkage).
  58     LocalCopy,
  59 }
  60
  61 impl<'a, 'tcx> TransItem<'tcx> {
  62
  63     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  64         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  65                   self.to_string(ccx.tcx()),
  66                   self.to_raw_string(),
  67                   ccx.codegen_unit().name());
  68
  69         // (*) This code executes in the context of a dep-node for the
  70         // entire CGU. In some cases, we introduce dep-nodes for
  71         // particular items that we are translating (these nodes will
  72         // have read edges coming into the CGU node). These smaller
  73         // nodes are not needed for correctness -- we always
  74         // invalidate an entire CGU at a time -- but they enable
  75         // finer-grained testing, since you can write tests that check
  76         // that the incoming edges to a particular fn are from a
  77         // particular set.
  78
  79         match *self {
  80             TransItem::Static(node_id) => {
  81                 let def_id = ccx.tcx().hir.local_def_id(node_id);
  82                 let _task = ccx.tcx().dep_graph.in_task(DepNode::TransCrateItem(def_id)); // (*)
  83                 let item = ccx.tcx().hir.expect_item(node_id);
  84                 if let hir::ItemStatic(_, m, _) = item.node {
  85                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  86                         Ok(_) => { /* Cool, everything's alright. */ },
  87                         Err(err) => {
  88                             // FIXME: shouldn't this be a `span_err`?
  89                             fatal_const_eval_err(
  90                                 ccx.tcx(), &err, item.span, "static");
  91                         }
  92                     };
  93                 } else {
  94                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  95                 }
  96             }
  97             TransItem::Fn(instance) => {
  98                 let _task = ccx.tcx().dep_graph.in_task(
  99                     DepNode::TransCrateItem(instance.def)); // (*)
 100
 101                 base::trans_instance(&ccx, instance);
 102             }
 103             TransItem::DropGlue(dg) => {
 104                 glue::implement_drop_glue(&ccx, dg);
 105             }
 106         }
 107
 108         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
 109                self.to_string(ccx.tcx()),
 110                self.to_raw_string(),
 111                ccx.codegen_unit().name());
 112     }
 113
 114     pub fn predefine(&self,
 115                      ccx: &CrateContext<'a, 'tcx>,
 116                      linkage: llvm::Linkage) {
 117         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 118                self.to_string(ccx.tcx()),
 119                self.to_raw_string(),
 120                ccx.codegen_unit().name());
 121
 122         let symbol_name = ccx.symbol_map()
 123                              .get_or_compute(ccx.shared(), *self);
 124
 125         debug!("symbol {}", &symbol_name);
 126
 127         match *self {
 128             TransItem::Static(node_id) => {
 129                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 130             }
 131             TransItem::Fn(instance) => {
 132                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 133             }
 134             TransItem::DropGlue(dg) => {
 135                 TransItem::predefine_drop_glue(ccx, dg, linkage, &symbol_name);
 136             }
 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 ty = common::def_ty(ccx.shared(), def_id, Substs::empty());
 151         let llty = type_of::type_of(ccx, ty);
 152
 153         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 154             ccx.sess().span_fatal(ccx.tcx().hir.span(node_id),
 155                 &format!("symbol `{}` is already defined", symbol_name))
 156         });
 157
 158         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 159
 160         let instance = Instance::mono(ccx.shared(), def_id);
 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::def_ty(ccx.shared(), instance.def, instance.substs);
 173         let attrs = ccx.tcx().get_attrs(instance.def);
 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         match ccx.tcx().def_key(instance.def).disambiguated_data.data {
 184             DefPathData::StructCtor |
 185             DefPathData::EnumVariant(..) |
 186             DefPathData::ClosureExpr => {
 187                 attributes::inline(lldecl, attributes::InlineAttr::Hint);
 188             }
 189             _ => {}
 190         }
 191
 192         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 193
 194         ccx.instances().borrow_mut().insert(instance, lldecl);
 195     }
 196
 197     fn predefine_drop_glue(ccx: &CrateContext<'a, 'tcx>,
 198                            dg: glue::DropGlueKind<'tcx>,
 199                            linkage: llvm::Linkage,
 200                            symbol_name: &str) {
 201         let tcx = ccx.tcx();
 202         assert_eq!(dg.ty(), glue::get_drop_glue_type(ccx.shared(), dg.ty()));
 203         let t = dg.ty();
 204
 205         let sig = tcx.mk_fn_sig(
 206             iter::once(tcx.mk_mut_ptr(t)),
 207             tcx.mk_nil(),
 208             false,
 209             hir::Unsafety::Normal,
 210             Abi::Rust
 211         );
 212
 213         debug!("predefine_drop_glue: sig={}", sig);
 214
 215         let fn_ty = FnType::new(ccx, sig, &[]);
 216         let llfnty = fn_ty.llvm_type(ccx);
 217
 218         assert!(declare::get_defined_value(ccx, symbol_name).is_none());
 219         let llfn = declare::declare_cfn(ccx, symbol_name, llfnty);
 220         unsafe { llvm::LLVMRustSetLinkage(llfn, linkage) };
 221         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 222            linkage == llvm::Linkage::WeakODRLinkage {
 223             llvm::SetUniqueComdat(ccx.llmod(), llfn);
 224         }
 225         attributes::set_frame_pointer_elimination(ccx, llfn);
 226         ccx.drop_glues().borrow_mut().insert(dg, (llfn, fn_ty));
 227     }
 228
 229     pub fn compute_symbol_name(&self,
 230                                scx: &SharedCrateContext<'a, 'tcx>) -> String {
 231         match *self {
 232             TransItem::Fn(instance) => instance.symbol_name(scx),
 233             TransItem::Static(node_id) => {
 234                 let def_id = scx.tcx().hir.local_def_id(node_id);
 235                 Instance::mono(scx, def_id).symbol_name(scx)
 236             }
 237             TransItem::DropGlue(dg) => {
 238                 let prefix = match dg {
 239                     DropGlueKind::Ty(_) => "drop",
 240                     DropGlueKind::TyContents(_) => "drop_contents",
 241                 };
 242                 symbol_names::exported_name_from_type_and_prefix(scx, dg.ty(), prefix)
 243             }
 244         }
 245     }
 246
 247     pub fn is_from_extern_crate(&self) -> bool {
 248         match *self {
 249             TransItem::Fn(ref instance) => !instance.def.is_local(),
 250             TransItem::DropGlue(..) |
 251             TransItem::Static(..)   => false,
 252         }
 253     }
 254
 255     pub fn instantiation_mode(&self,
 256                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 257                               -> InstantiationMode {
 258         match *self {
 259             TransItem::Fn(ref instance) => {
 260                 if self.explicit_linkage(tcx).is_none() &&
 261                     common::requests_inline(tcx, instance.def)
 262                 {
 263                     InstantiationMode::LocalCopy
 264                 } else {
 265                     InstantiationMode::GloballyShared
 266                 }
 267             }
 268             TransItem::DropGlue(..) => InstantiationMode::LocalCopy,
 269             TransItem::Static(..) => InstantiationMode::GloballyShared,
 270         }
 271     }
 272
 273     pub fn is_generic_fn(&self) -> bool {
 274         match *self {
 275             TransItem::Fn(ref instance) => {
 276                 instance.substs.types().next().is_some()
 277             }
 278             TransItem::DropGlue(..) |
 279             TransItem::Static(..)   => false,
 280         }
 281     }
 282
 283     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 284         let def_id = match *self {
 285             TransItem::Fn(ref instance) => instance.def,
 286             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 287             TransItem::DropGlue(..) => return None,
 288         };
 289
 290         let attributes = tcx.get_attrs(def_id);
 291         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 292             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 293                 Some(linkage)
 294             } else {
 295                 let span = tcx.hir.span_if_local(def_id);
 296                 if let Some(span) = span {
 297                     tcx.sess.span_fatal(span, "invalid linkage specified")
 298                 } else {
 299                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 300                 }
 301             }
 302         } else {
 303             None
 304         }
 305     }
 306
 307     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 308         let hir_map = &tcx.hir;
 309
 310         return match *self {
 311             TransItem::DropGlue(dg) => {
 312                 let mut s = String::with_capacity(32);
 313                 match dg {
 314                     DropGlueKind::Ty(_) => s.push_str("drop-glue "),
 315                     DropGlueKind::TyContents(_) => s.push_str("drop-glue-contents "),
 316                 };
 317                 let printer = DefPathBasedNames::new(tcx, false, false);
 318                 printer.push_type_name(dg.ty(), &mut s);
 319                 s
 320             }
 321             TransItem::Fn(instance) => {
 322                 to_string_internal(tcx, "fn ", instance)
 323             },
 324             TransItem::Static(node_id) => {
 325                 let def_id = hir_map.local_def_id(node_id);
 326                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 327                 to_string_internal(tcx, "static ", instance)
 328             },
 329         };
 330
 331         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 332                                         prefix: &str,
 333                                         instance: Instance<'tcx>)
 334                                         -> String {
 335             let mut result = String::with_capacity(32);
 336             result.push_str(prefix);
 337             let printer = DefPathBasedNames::new(tcx, false, false);
 338             printer.push_instance_as_string(instance, &mut result);
 339             result
 340         }
 341     }
 342
 343     pub fn to_raw_string(&self) -> String {
 344         match *self {
 345             TransItem::DropGlue(dg) => {
 346                 let prefix = match dg {
 347                     DropGlueKind::Ty(_) => "Ty",
 348                     DropGlueKind::TyContents(_) => "TyContents",
 349                 };
 350                 format!("DropGlue({}: {})", prefix, dg.ty() as *const _ as usize)
 351             }
 352             TransItem::Fn(instance) => {
 353                 format!("Fn({:?}, {})",
 354                          instance.def,
 355                          instance.substs.as_ptr() as usize)
 356             }
 357             TransItem::Static(id) => {
 358                 format!("Static({:?})", id)
 359             }
 360         }
 361     }
 362 }
 363
 364
 365 //=-----------------------------------------------------------------------------
 366 // TransItem String Keys
 367 //=-----------------------------------------------------------------------------
 368
 369 // The code below allows for producing a unique string key for a trans item.
 370 // These keys are used by the handwritten auto-tests, so they need to be
 371 // predictable and human-readable.
 372 //
 373 // Note: A lot of this could looks very similar to what's already in the
 374 //       ppaux module. It would be good to refactor things so we only have one
 375 //       parameterizable implementation for printing types.
 376
 377 /// Same as `unique_type_name()` but with the result pushed onto the given
 378 /// `output` parameter.
 379 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 380     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 381     omit_disambiguators: bool,
 382     omit_local_crate_name: bool,
 383 }
 384
 385 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 386     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 387                omit_disambiguators: bool,
 388                omit_local_crate_name: bool)
 389                -> Self {
 390         DefPathBasedNames {
 391             tcx: tcx,
 392             omit_disambiguators: omit_disambiguators,
 393             omit_local_crate_name: omit_local_crate_name,
 394         }
 395     }
 396
 397     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 398         match t.sty {
 399             ty::TyBool              => output.push_str("bool"),
 400             ty::TyChar              => output.push_str("char"),
 401             ty::TyStr               => output.push_str("str"),
 402             ty::TyNever             => output.push_str("!"),
 403             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 404             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 405             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 406             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 407             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 408             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 409             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 410             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 411             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 412             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 413             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 414             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 415             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 416             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 417             ty::TyAdt(adt_def, substs) => {
 418                 self.push_def_path(adt_def.did, output);
 419                 self.push_type_params(substs, iter::empty(), output);
 420             },
 421             ty::TyTuple(component_types, _) => {
 422                 output.push('(');
 423                 for &component_type in component_types {
 424                     self.push_type_name(component_type, output);
 425                     output.push_str(", ");
 426                 }
 427                 if !component_types.is_empty() {
 428                     output.pop();
 429                     output.pop();
 430                 }
 431                 output.push(')');
 432             },
 433             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 434                 output.push('*');
 435                 match mutbl {
 436                     hir::MutImmutable => output.push_str("const "),
 437                     hir::MutMutable => output.push_str("mut "),
 438                 }
 439
 440                 self.push_type_name(inner_type, output);
 441             },
 442             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 443                 output.push('&');
 444                 if mutbl == hir::MutMutable {
 445                     output.push_str("mut ");
 446                 }
 447
 448                 self.push_type_name(inner_type, output);
 449             },
 450             ty::TyArray(inner_type, len) => {
 451                 output.push('[');
 452                 self.push_type_name(inner_type, output);
 453                 write!(output, "; {}", len).unwrap();
 454                 output.push(']');
 455             },
 456             ty::TySlice(inner_type) => {
 457                 output.push('[');
 458                 self.push_type_name(inner_type, output);
 459                 output.push(']');
 460             },
 461             ty::TyDynamic(ref trait_data, ..) => {
 462                 if let Some(principal) = trait_data.principal() {
 463                     self.push_def_path(principal.def_id(), output);
 464                     self.push_type_params(principal.skip_binder().substs,
 465                         trait_data.projection_bounds(),
 466                         output);
 467                 }
 468             },
 469             ty::TyFnDef(.., sig) |
 470             ty::TyFnPtr(sig) => {
 471                 if sig.unsafety() == hir::Unsafety::Unsafe {
 472                     output.push_str("unsafe ");
 473                 }
 474
 475                 let abi = sig.abi();
 476                 if abi != ::abi::Abi::Rust {
 477                     output.push_str("extern \"");
 478                     output.push_str(abi.name());
 479                     output.push_str("\" ");
 480                 }
 481
 482                 output.push_str("fn(");
 483
 484                 let sig = self.tcx.erase_late_bound_regions_and_normalize(&sig);
 485
 486                 if !sig.inputs().is_empty() {
 487                     for &parameter_type in sig.inputs() {
 488                         self.push_type_name(parameter_type, output);
 489                         output.push_str(", ");
 490                     }
 491                     output.pop();
 492                     output.pop();
 493                 }
 494
 495                 if sig.variadic {
 496                     if !sig.inputs().is_empty() {
 497                         output.push_str(", ...");
 498                     } else {
 499                         output.push_str("...");
 500                     }
 501                 }
 502
 503                 output.push(')');
 504
 505                 if !sig.output().is_nil() {
 506                     output.push_str(" -> ");
 507                     self.push_type_name(sig.output(), output);
 508                 }
 509             },
 510             ty::TyClosure(def_id, ref closure_substs) => {
 511                 self.push_def_path(def_id, output);
 512                 let generics = self.tcx.item_generics(self.tcx.closure_base_def_id(def_id));
 513                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 514                 self.push_type_params(substs, iter::empty(), output);
 515             }
 516             ty::TyError |
 517             ty::TyInfer(_) |
 518             ty::TyProjection(..) |
 519             ty::TyParam(_) |
 520             ty::TyAnon(..) => {
 521                 bug!("DefPathBasedNames: Trying to create type name for \
 522                                          unexpected type: {:?}", t);
 523             }
 524         }
 525     }
 526
 527     pub fn push_def_path(&self,
 528                          def_id: DefId,
 529                          output: &mut String) {
 530         let def_path = self.tcx.def_path(def_id);
 531
 532         // some_crate::
 533         if !(self.omit_local_crate_name && def_id.is_local()) {
 534             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 535             output.push_str("::");
 536         }
 537
 538         // foo::bar::ItemName::
 539         for part in self.tcx.def_path(def_id).data {
 540             if self.omit_disambiguators {
 541                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 542             } else {
 543                 write!(output, "{}[{}]::",
 544                        part.data.as_interned_str(),
 545                        part.disambiguator).unwrap();
 546             }
 547         }
 548
 549         // remove final "::"
 550         output.pop();
 551         output.pop();
 552     }
 553
 554     fn push_type_params<I>(&self,
 555                             substs: &Substs<'tcx>,
 556                             projections: I,
 557                             output: &mut String)
 558         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 559     {
 560         let mut projections = projections.peekable();
 561         if substs.types().next().is_none() && projections.peek().is_none() {
 562             return;
 563         }
 564
 565         output.push('<');
 566
 567         for type_parameter in substs.types() {
 568             self.push_type_name(type_parameter, output);
 569             output.push_str(", ");
 570         }
 571
 572         for projection in projections {
 573             let projection = projection.skip_binder();
 574             let name = &projection.item_name.as_str();
 575             output.push_str(name);
 576             output.push_str("=");
 577             self.push_type_name(projection.ty, output);
 578             output.push_str(", ");
 579         }
 580
 581         output.pop();
 582         output.pop();
 583
 584         output.push('>');
 585     }
 586
 587     pub fn push_instance_as_string(&self,
 588                                    instance: Instance<'tcx>,
 589                                    output: &mut String) {
 590         self.push_def_path(instance.def, output);
 591         self.push_type_params(instance.substs, iter::empty(), output);
 592     }
 593 }