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::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 = common::def_ty(ccx.shared(), def_id, Substs::empty());
 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 mono_ty = common::def_ty(ccx.shared(), instance.def, instance.substs);
 172         let attrs = ccx.tcx().get_attrs(instance.def);
 173         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 174         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 175         base::set_link_section(ccx, lldecl, &attrs);
 176         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 177             linkage == llvm::Linkage::WeakODRLinkage {
 178             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 179         }
 180
 181         if let ty::TyClosure(..) = mono_ty.sty {
 182             // set an inline hint for all closures
 183             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 184         }
 185
 186         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 187
 188         ccx.instances().borrow_mut().insert(instance, lldecl);
 189     }
 190
 191     fn predefine_drop_glue(ccx: &CrateContext<'a, 'tcx>,
 192                            dg: glue::DropGlueKind<'tcx>,
 193                            linkage: llvm::Linkage,
 194                            symbol_name: &str) {
 195         let tcx = ccx.tcx();
 196         assert_eq!(dg.ty(), glue::get_drop_glue_type(ccx.shared(), dg.ty()));
 197         let t = dg.ty();
 198
 199         let sig = tcx.mk_fn_sig(
 200             iter::once(tcx.mk_mut_ptr(t)),
 201             tcx.mk_nil(),
 202             false,
 203             hir::Unsafety::Normal,
 204             Abi::Rust
 205         );
 206
 207         debug!("predefine_drop_glue: sig={}", sig);
 208
 209         let fn_ty = FnType::new(ccx, sig, &[]);
 210         let llfnty = fn_ty.llvm_type(ccx);
 211
 212         assert!(declare::get_defined_value(ccx, symbol_name).is_none());
 213         let llfn = declare::declare_cfn(ccx, symbol_name, llfnty);
 214         unsafe { llvm::LLVMRustSetLinkage(llfn, linkage) };
 215         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 216            linkage == llvm::Linkage::WeakODRLinkage {
 217             llvm::SetUniqueComdat(ccx.llmod(), llfn);
 218         }
 219         attributes::set_frame_pointer_elimination(ccx, llfn);
 220         ccx.drop_glues().borrow_mut().insert(dg, (llfn, fn_ty));
 221     }
 222
 223     pub fn compute_symbol_name(&self,
 224                                scx: &SharedCrateContext<'a, 'tcx>) -> String {
 225         match *self {
 226             TransItem::Fn(instance) => instance.symbol_name(scx),
 227             TransItem::Static(node_id) => {
 228                 let def_id = scx.tcx().hir.local_def_id(node_id);
 229                 Instance::mono(scx, def_id).symbol_name(scx)
 230             }
 231             TransItem::DropGlue(dg) => {
 232                 let prefix = match dg {
 233                     DropGlueKind::Ty(_) => "drop",
 234                     DropGlueKind::TyContents(_) => "drop_contents",
 235                 };
 236                 symbol_names::exported_name_from_type_and_prefix(scx, dg.ty(), prefix)
 237             }
 238         }
 239     }
 240
 241     pub fn is_from_extern_crate(&self) -> bool {
 242         match *self {
 243             TransItem::Fn(ref instance) => !instance.def.is_local(),
 244             TransItem::DropGlue(..) |
 245             TransItem::Static(..)   => false,
 246         }
 247     }
 248
 249     pub fn instantiation_mode(&self,
 250                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 251                               -> InstantiationMode {
 252         match *self {
 253             TransItem::Fn(ref instance) => {
 254                 if self.explicit_linkage(tcx).is_none() &&
 255                    (common::is_closure(tcx, instance.def) ||
 256                     attr::requests_inline(&tcx.get_attrs(instance.def)[..])) {
 257                     InstantiationMode::LocalCopy
 258                 } else {
 259                     InstantiationMode::GloballyShared
 260                 }
 261             }
 262             TransItem::DropGlue(..) => InstantiationMode::LocalCopy,
 263             TransItem::Static(..) => InstantiationMode::GloballyShared,
 264         }
 265     }
 266
 267     pub fn is_generic_fn(&self) -> bool {
 268         match *self {
 269             TransItem::Fn(ref instance) => {
 270                 instance.substs.types().next().is_some()
 271             }
 272             TransItem::DropGlue(..) |
 273             TransItem::Static(..)   => false,
 274         }
 275     }
 276
 277     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 278         let def_id = match *self {
 279             TransItem::Fn(ref instance) => instance.def,
 280             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 281             TransItem::DropGlue(..) => return None,
 282         };
 283
 284         let attributes = tcx.get_attrs(def_id);
 285         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 286             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 287                 Some(linkage)
 288             } else {
 289                 let span = tcx.hir.span_if_local(def_id);
 290                 if let Some(span) = span {
 291                     tcx.sess.span_fatal(span, "invalid linkage specified")
 292                 } else {
 293                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 294                 }
 295             }
 296         } else {
 297             None
 298         }
 299     }
 300
 301     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 302         let hir_map = &tcx.hir;
 303
 304         return match *self {
 305             TransItem::DropGlue(dg) => {
 306                 let mut s = String::with_capacity(32);
 307                 match dg {
 308                     DropGlueKind::Ty(_) => s.push_str("drop-glue "),
 309                     DropGlueKind::TyContents(_) => s.push_str("drop-glue-contents "),
 310                 };
 311                 let printer = DefPathBasedNames::new(tcx, false, false);
 312                 printer.push_type_name(dg.ty(), &mut s);
 313                 s
 314             }
 315             TransItem::Fn(instance) => {
 316                 to_string_internal(tcx, "fn ", instance)
 317             },
 318             TransItem::Static(node_id) => {
 319                 let def_id = hir_map.local_def_id(node_id);
 320                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 321                 to_string_internal(tcx, "static ", instance)
 322             },
 323         };
 324
 325         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 326                                         prefix: &str,
 327                                         instance: Instance<'tcx>)
 328                                         -> String {
 329             let mut result = String::with_capacity(32);
 330             result.push_str(prefix);
 331             let printer = DefPathBasedNames::new(tcx, false, false);
 332             printer.push_instance_as_string(instance, &mut result);
 333             result
 334         }
 335     }
 336
 337     pub fn to_raw_string(&self) -> String {
 338         match *self {
 339             TransItem::DropGlue(dg) => {
 340                 let prefix = match dg {
 341                     DropGlueKind::Ty(_) => "Ty",
 342                     DropGlueKind::TyContents(_) => "TyContents",
 343                 };
 344                 format!("DropGlue({}: {})", prefix, dg.ty() as *const _ as usize)
 345             }
 346             TransItem::Fn(instance) => {
 347                 format!("Fn({:?}, {})",
 348                          instance.def,
 349                          instance.substs.as_ptr() as usize)
 350             }
 351             TransItem::Static(id) => {
 352                 format!("Static({:?})", id)
 353             }
 354         }
 355     }
 356 }
 357
 358
 359 //=-----------------------------------------------------------------------------
 360 // TransItem String Keys
 361 //=-----------------------------------------------------------------------------
 362
 363 // The code below allows for producing a unique string key for a trans item.
 364 // These keys are used by the handwritten auto-tests, so they need to be
 365 // predictable and human-readable.
 366 //
 367 // Note: A lot of this could looks very similar to what's already in the
 368 //       ppaux module. It would be good to refactor things so we only have one
 369 //       parameterizable implementation for printing types.
 370
 371 /// Same as `unique_type_name()` but with the result pushed onto the given
 372 /// `output` parameter.
 373 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 374     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 375     omit_disambiguators: bool,
 376     omit_local_crate_name: bool,
 377 }
 378
 379 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 380     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 381                omit_disambiguators: bool,
 382                omit_local_crate_name: bool)
 383                -> Self {
 384         DefPathBasedNames {
 385             tcx: tcx,
 386             omit_disambiguators: omit_disambiguators,
 387             omit_local_crate_name: omit_local_crate_name,
 388         }
 389     }
 390
 391     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 392         match t.sty {
 393             ty::TyBool              => output.push_str("bool"),
 394             ty::TyChar              => output.push_str("char"),
 395             ty::TyStr               => output.push_str("str"),
 396             ty::TyNever             => output.push_str("!"),
 397             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 398             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 399             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 400             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 401             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 402             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 403             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 404             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 405             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 406             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 407             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 408             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 409             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 410             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 411             ty::TyAdt(adt_def, substs) => {
 412                 self.push_def_path(adt_def.did, output);
 413                 self.push_type_params(substs, iter::empty(), output);
 414             },
 415             ty::TyTuple(component_types, _) => {
 416                 output.push('(');
 417                 for &component_type in component_types {
 418                     self.push_type_name(component_type, output);
 419                     output.push_str(", ");
 420                 }
 421                 if !component_types.is_empty() {
 422                     output.pop();
 423                     output.pop();
 424                 }
 425                 output.push(')');
 426             },
 427             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 428                 output.push('*');
 429                 match mutbl {
 430                     hir::MutImmutable => output.push_str("const "),
 431                     hir::MutMutable => output.push_str("mut "),
 432                 }
 433
 434                 self.push_type_name(inner_type, output);
 435             },
 436             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 437                 output.push('&');
 438                 if mutbl == hir::MutMutable {
 439                     output.push_str("mut ");
 440                 }
 441
 442                 self.push_type_name(inner_type, output);
 443             },
 444             ty::TyArray(inner_type, len) => {
 445                 output.push('[');
 446                 self.push_type_name(inner_type, output);
 447                 write!(output, "; {}", len).unwrap();
 448                 output.push(']');
 449             },
 450             ty::TySlice(inner_type) => {
 451                 output.push('[');
 452                 self.push_type_name(inner_type, output);
 453                 output.push(']');
 454             },
 455             ty::TyDynamic(ref trait_data, ..) => {
 456                 if let Some(principal) = trait_data.principal() {
 457                     self.push_def_path(principal.def_id(), output);
 458                     self.push_type_params(principal.skip_binder().substs,
 459                         trait_data.projection_bounds(),
 460                         output);
 461                 }
 462             },
 463             ty::TyFnDef(.., sig) |
 464             ty::TyFnPtr(sig) => {
 465                 if sig.unsafety() == hir::Unsafety::Unsafe {
 466                     output.push_str("unsafe ");
 467                 }
 468
 469                 let abi = sig.abi();
 470                 if abi != ::abi::Abi::Rust {
 471                     output.push_str("extern \"");
 472                     output.push_str(abi.name());
 473                     output.push_str("\" ");
 474                 }
 475
 476                 output.push_str("fn(");
 477
 478                 let sig = self.tcx.erase_late_bound_regions_and_normalize(&sig);
 479
 480                 if !sig.inputs().is_empty() {
 481                     for &parameter_type in sig.inputs() {
 482                         self.push_type_name(parameter_type, output);
 483                         output.push_str(", ");
 484                     }
 485                     output.pop();
 486                     output.pop();
 487                 }
 488
 489                 if sig.variadic {
 490                     if !sig.inputs().is_empty() {
 491                         output.push_str(", ...");
 492                     } else {
 493                         output.push_str("...");
 494                     }
 495                 }
 496
 497                 output.push(')');
 498
 499                 if !sig.output().is_nil() {
 500                     output.push_str(" -> ");
 501                     self.push_type_name(sig.output(), output);
 502                 }
 503             },
 504             ty::TyClosure(def_id, ref closure_substs) => {
 505                 self.push_def_path(def_id, output);
 506                 let generics = self.tcx.item_generics(self.tcx.closure_base_def_id(def_id));
 507                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 508                 self.push_type_params(substs, iter::empty(), output);
 509             }
 510             ty::TyError |
 511             ty::TyInfer(_) |
 512             ty::TyProjection(..) |
 513             ty::TyParam(_) |
 514             ty::TyAnon(..) => {
 515                 bug!("DefPathBasedNames: Trying to create type name for \
 516                                          unexpected type: {:?}", t);
 517             }
 518         }
 519     }
 520
 521     pub fn push_def_path(&self,
 522                          def_id: DefId,
 523                          output: &mut String) {
 524         let def_path = self.tcx.def_path(def_id);
 525
 526         // some_crate::
 527         if !(self.omit_local_crate_name && def_id.is_local()) {
 528             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 529             output.push_str("::");
 530         }
 531
 532         // foo::bar::ItemName::
 533         for part in self.tcx.def_path(def_id).data {
 534             if self.omit_disambiguators {
 535                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 536             } else {
 537                 write!(output, "{}[{}]::",
 538                        part.data.as_interned_str(),
 539                        part.disambiguator).unwrap();
 540             }
 541         }
 542
 543         // remove final "::"
 544         output.pop();
 545         output.pop();
 546     }
 547
 548     fn push_type_params<I>(&self,
 549                             substs: &Substs<'tcx>,
 550                             projections: I,
 551                             output: &mut String)
 552         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 553     {
 554         let mut projections = projections.peekable();
 555         if substs.types().next().is_none() && projections.peek().is_none() {
 556             return;
 557         }
 558
 559         output.push('<');
 560
 561         for type_parameter in substs.types() {
 562             self.push_type_name(type_parameter, output);
 563             output.push_str(", ");
 564         }
 565
 566         for projection in projections {
 567             let projection = projection.skip_binder();
 568             let name = &projection.item_name.as_str();
 569             output.push_str(name);
 570             output.push_str("=");
 571             self.push_type_name(projection.ty, output);
 572             output.push_str(", ");
 573         }
 574
 575         output.pop();
 576         output.pop();
 577
 578         output.push('>');
 579     }
 580
 581     pub fn push_instance_as_string(&self,
 582                                    instance: Instance<'tcx>,
 583                                    output: &mut String) {
 584         self.push_def_path(instance.def, output);
 585         self.push_type_params(instance.substs, iter::empty(), output);
 586     }
 587 }