src/librustc_trans/trans_item.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Walks the crate looking for items/impl-items/trait-items that have
  12 //! either a `rustc_symbol_name` or `rustc_item_path` attribute and
  13 //! generates an error giving, respectively, the symbol name or
  14 //! item-path. This is used for unit testing the code that generates
  15 //! paths etc in all kinds of annoying scenarios.
  16
  17 use asm;
  18 use attributes;
  19 use base;
  20 use consts;
  21 use context::CrateContext;
  22 use common;
  23 use declare;
  24 use llvm;
  25 use monomorphize::Instance;
  26 use rustc::dep_graph::DepNode;
  27 use rustc::hir;
  28 use rustc::hir::def_id::DefId;
  29 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  30 use rustc::ty::subst::Substs;
  31 use syntax::ast::{self, NodeId};
  32 use syntax::attr;
  33 use type_of;
  34 use back::symbol_names;
  35 use std::fmt::Write;
  36 use std::iter;
  37
  38 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  39 pub enum TransItem<'tcx> {
  40     Fn(Instance<'tcx>),
  41     Static(NodeId),
  42     GlobalAsm(NodeId),
  43 }
  44
  45 /// Describes how a translation item will be instantiated in object files.
  46 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
  47 pub enum InstantiationMode {
  48     /// There will be exactly one instance of the given TransItem. It will have
  49     /// external linkage so that it can be linked to from other codegen units.
  50     GloballyShared,
  51
  52     /// Each codegen unit containing a reference to the given TransItem will
  53     /// have its own private copy of the function (with internal linkage).
  54     LocalCopy,
  55 }
  56
  57 impl<'a, 'tcx> TransItem<'tcx> {
  58
  59     pub fn define(&self, ccx: &CrateContext<'a, 'tcx>) {
  60         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  61                   self.to_string(ccx.tcx()),
  62                   self.to_raw_string(),
  63                   ccx.codegen_unit().name());
  64
  65         // (*) This code executes in the context of a dep-node for the
  66         // entire CGU. In some cases, we introduce dep-nodes for
  67         // particular items that we are translating (these nodes will
  68         // have read edges coming into the CGU node). These smaller
  69         // nodes are not needed for correctness -- we always
  70         // invalidate an entire CGU at a time -- but they enable
  71         // finer-grained testing, since you can write tests that check
  72         // that the incoming edges to a particular fn are from a
  73         // particular set.
  74
  75         match *self {
  76             TransItem::Static(node_id) => {
  77                 let def_id = ccx.tcx().hir.local_def_id(node_id);
  78                 let _task = ccx.tcx().dep_graph.in_task(DepNode::TransCrateItem(def_id)); // (*)
  79                 let item = ccx.tcx().hir.expect_item(node_id);
  80                 if let hir::ItemStatic(_, m, _) = item.node {
  81                     match consts::trans_static(&ccx, m, item.id, &item.attrs) {
  82                         Ok(_) => { /* Cool, everything's alright. */ },
  83                         Err(err) => {
  84                             err.report(ccx.tcx(), item.span, "static");
  85                         }
  86                     };
  87                 } else {
  88                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  89                 }
  90             }
  91             TransItem::GlobalAsm(node_id) => {
  92                 let item = ccx.tcx().hir.expect_item(node_id);
  93                 if let hir::ItemGlobalAsm(ref ga) = item.node {
  94                     asm::trans_global_asm(ccx, ga);
  95                 } else {
  96                     span_bug!(item.span, "Mismatch between hir::Item type and TransItem type")
  97                 }
  98             }
  99             TransItem::Fn(instance) => {
 100                 let _task = ccx.tcx().dep_graph.in_task(
 101                     DepNode::TransCrateItem(instance.def_id())); // (*)
 102
 103                 base::trans_instance(&ccx, instance);
 104             }
 105         }
 106
 107         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
 108                self.to_string(ccx.tcx()),
 109                self.to_raw_string(),
 110                ccx.codegen_unit().name());
 111     }
 112
 113     pub fn predefine(&self,
 114                      ccx: &CrateContext<'a, 'tcx>,
 115                      linkage: llvm::Linkage) {
 116         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
 117                self.to_string(ccx.tcx()),
 118                self.to_raw_string(),
 119                ccx.codegen_unit().name());
 120
 121         let symbol_name = ccx.symbol_cache().get(*self);
 122
 123         debug!("symbol {}", &symbol_name);
 124
 125         match *self {
 126             TransItem::Static(node_id) => {
 127                 TransItem::predefine_static(ccx, node_id, linkage, &symbol_name);
 128             }
 129             TransItem::Fn(instance) => {
 130                 TransItem::predefine_fn(ccx, instance, linkage, &symbol_name);
 131             }
 132             TransItem::GlobalAsm(..) => {}
 133         }
 134
 135         debug!("END PREDEFINING '{} ({})' in cgu {}",
 136                self.to_string(ccx.tcx()),
 137                self.to_raw_string(),
 138                ccx.codegen_unit().name());
 139     }
 140
 141     fn predefine_static(ccx: &CrateContext<'a, 'tcx>,
 142                         node_id: ast::NodeId,
 143                         linkage: llvm::Linkage,
 144                         symbol_name: &str) {
 145         let def_id = ccx.tcx().hir.local_def_id(node_id);
 146         let instance = Instance::mono(ccx.tcx(), def_id);
 147         let ty = common::instance_ty(ccx.shared(), &instance);
 148         let llty = type_of::type_of(ccx, ty);
 149
 150         let g = declare::define_global(ccx, symbol_name, llty).unwrap_or_else(|| {
 151             ccx.sess().span_fatal(ccx.tcx().hir.span(node_id),
 152                 &format!("symbol `{}` is already defined", symbol_name))
 153         });
 154
 155         unsafe { llvm::LLVMRustSetLinkage(g, linkage) };
 156
 157         ccx.instances().borrow_mut().insert(instance, g);
 158         ccx.statics().borrow_mut().insert(g, def_id);
 159     }
 160
 161     fn predefine_fn(ccx: &CrateContext<'a, 'tcx>,
 162                     instance: Instance<'tcx>,
 163                     linkage: llvm::Linkage,
 164                     symbol_name: &str) {
 165         assert!(!instance.substs.needs_infer() &&
 166                 !instance.substs.has_param_types());
 167
 168         let mono_ty = common::instance_ty(ccx.shared(), &instance);
 169         let attrs = instance.def.attrs(ccx.tcx());
 170         let lldecl = declare::declare_fn(ccx, symbol_name, mono_ty);
 171         unsafe { llvm::LLVMRustSetLinkage(lldecl, linkage) };
 172         base::set_link_section(ccx, lldecl, &attrs);
 173         if linkage == llvm::Linkage::LinkOnceODRLinkage ||
 174             linkage == llvm::Linkage::WeakODRLinkage {
 175             llvm::SetUniqueComdat(ccx.llmod(), lldecl);
 176         }
 177
 178         debug!("predefine_fn: mono_ty = {:?} instance = {:?}", mono_ty, instance);
 179         if common::is_inline_instance(ccx.tcx(), &instance) {
 180             attributes::inline(lldecl, attributes::InlineAttr::Hint);
 181         }
 182         attributes::from_fn_attrs(ccx, &attrs, lldecl);
 183
 184         ccx.instances().borrow_mut().insert(instance, lldecl);
 185     }
 186
 187     pub fn compute_symbol_name(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 188         match *self {
 189             TransItem::Fn(instance) => symbol_names::symbol_name(instance, tcx),
 190             TransItem::Static(node_id) => {
 191                 let def_id = tcx.hir.local_def_id(node_id);
 192                 symbol_names::symbol_name(Instance::mono(tcx, def_id), tcx)
 193             }
 194             TransItem::GlobalAsm(node_id) => {
 195                 let def_id = tcx.hir.local_def_id(node_id);
 196                 format!("global_asm_{:?}", def_id)
 197             }
 198         }
 199     }
 200
 201     pub fn instantiation_mode(&self,
 202                               tcx: TyCtxt<'a, 'tcx, 'tcx>)
 203                               -> InstantiationMode {
 204         match *self {
 205             TransItem::Fn(ref instance) => {
 206                 if self.explicit_linkage(tcx).is_none() &&
 207                     common::requests_inline(tcx, instance)
 208                 {
 209                     InstantiationMode::LocalCopy
 210                 } else {
 211                     InstantiationMode::GloballyShared
 212                 }
 213             }
 214             TransItem::Static(..) => InstantiationMode::GloballyShared,
 215             TransItem::GlobalAsm(..) => InstantiationMode::GloballyShared,
 216         }
 217     }
 218
 219     pub fn is_generic_fn(&self) -> bool {
 220         match *self {
 221             TransItem::Fn(ref instance) => {
 222                 instance.substs.types().next().is_some()
 223             }
 224             TransItem::Static(..) |
 225             TransItem::GlobalAsm(..) => false,
 226         }
 227     }
 228
 229     pub fn explicit_linkage(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Option<llvm::Linkage> {
 230         let def_id = match *self {
 231             TransItem::Fn(ref instance) => instance.def_id(),
 232             TransItem::Static(node_id) => tcx.hir.local_def_id(node_id),
 233             TransItem::GlobalAsm(..) => return None,
 234         };
 235
 236         let attributes = tcx.get_attrs(def_id);
 237         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
 238             if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
 239                 Some(linkage)
 240             } else {
 241                 let span = tcx.hir.span_if_local(def_id);
 242                 if let Some(span) = span {
 243                     tcx.sess.span_fatal(span, "invalid linkage specified")
 244                 } else {
 245                     tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
 246                 }
 247             }
 248         } else {
 249             None
 250         }
 251     }
 252
 253     pub fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {
 254         let hir_map = &tcx.hir;
 255
 256         return match *self {
 257             TransItem::Fn(instance) => {
 258                 to_string_internal(tcx, "fn ", instance)
 259             },
 260             TransItem::Static(node_id) => {
 261                 let def_id = hir_map.local_def_id(node_id);
 262                 let instance = Instance::new(def_id, tcx.intern_substs(&[]));
 263                 to_string_internal(tcx, "static ", instance)
 264             },
 265             TransItem::GlobalAsm(..) => {
 266                 "global_asm".to_string()
 267             }
 268         };
 269
 270         fn to_string_internal<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 271                                         prefix: &str,
 272                                         instance: Instance<'tcx>)
 273                                         -> String {
 274             let mut result = String::with_capacity(32);
 275             result.push_str(prefix);
 276             let printer = DefPathBasedNames::new(tcx, false, false);
 277             printer.push_instance_as_string(instance, &mut result);
 278             result
 279         }
 280     }
 281
 282     pub fn to_raw_string(&self) -> String {
 283         match *self {
 284             TransItem::Fn(instance) => {
 285                 format!("Fn({:?}, {})",
 286                          instance.def,
 287                          instance.substs.as_ptr() as usize)
 288             }
 289             TransItem::Static(id) => {
 290                 format!("Static({:?})", id)
 291             }
 292             TransItem::GlobalAsm(id) => {
 293                 format!("GlobalAsm({:?})", id)
 294             }
 295         }
 296     }
 297 }
 298
 299
 300 //=-----------------------------------------------------------------------------
 301 // TransItem String Keys
 302 //=-----------------------------------------------------------------------------
 303
 304 // The code below allows for producing a unique string key for a trans item.
 305 // These keys are used by the handwritten auto-tests, so they need to be
 306 // predictable and human-readable.
 307 //
 308 // Note: A lot of this could looks very similar to what's already in the
 309 //       ppaux module. It would be good to refactor things so we only have one
 310 //       parameterizable implementation for printing types.
 311
 312 /// Same as `unique_type_name()` but with the result pushed onto the given
 313 /// `output` parameter.
 314 pub struct DefPathBasedNames<'a, 'tcx: 'a> {
 315     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 316     omit_disambiguators: bool,
 317     omit_local_crate_name: bool,
 318 }
 319
 320 impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 321     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 322                omit_disambiguators: bool,
 323                omit_local_crate_name: bool)
 324                -> Self {
 325         DefPathBasedNames {
 326             tcx: tcx,
 327             omit_disambiguators: omit_disambiguators,
 328             omit_local_crate_name: omit_local_crate_name,
 329         }
 330     }
 331
 332     pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String) {
 333         match t.sty {
 334             ty::TyBool              => output.push_str("bool"),
 335             ty::TyChar              => output.push_str("char"),
 336             ty::TyStr               => output.push_str("str"),
 337             ty::TyNever             => output.push_str("!"),
 338             ty::TyInt(ast::IntTy::Is)    => output.push_str("isize"),
 339             ty::TyInt(ast::IntTy::I8)    => output.push_str("i8"),
 340             ty::TyInt(ast::IntTy::I16)   => output.push_str("i16"),
 341             ty::TyInt(ast::IntTy::I32)   => output.push_str("i32"),
 342             ty::TyInt(ast::IntTy::I64)   => output.push_str("i64"),
 343             ty::TyInt(ast::IntTy::I128)   => output.push_str("i128"),
 344             ty::TyUint(ast::UintTy::Us)   => output.push_str("usize"),
 345             ty::TyUint(ast::UintTy::U8)   => output.push_str("u8"),
 346             ty::TyUint(ast::UintTy::U16)  => output.push_str("u16"),
 347             ty::TyUint(ast::UintTy::U32)  => output.push_str("u32"),
 348             ty::TyUint(ast::UintTy::U64)  => output.push_str("u64"),
 349             ty::TyUint(ast::UintTy::U128)  => output.push_str("u128"),
 350             ty::TyFloat(ast::FloatTy::F32) => output.push_str("f32"),
 351             ty::TyFloat(ast::FloatTy::F64) => output.push_str("f64"),
 352             ty::TyAdt(adt_def, substs) => {
 353                 self.push_def_path(adt_def.did, output);
 354                 self.push_type_params(substs, iter::empty(), output);
 355             },
 356             ty::TyTuple(component_types, _) => {
 357                 output.push('(');
 358                 for &component_type in component_types {
 359                     self.push_type_name(component_type, output);
 360                     output.push_str(", ");
 361                 }
 362                 if !component_types.is_empty() {
 363                     output.pop();
 364                     output.pop();
 365                 }
 366                 output.push(')');
 367             },
 368             ty::TyRawPtr(ty::TypeAndMut { ty: inner_type, mutbl } ) => {
 369                 output.push('*');
 370                 match mutbl {
 371                     hir::MutImmutable => output.push_str("const "),
 372                     hir::MutMutable => output.push_str("mut "),
 373                 }
 374
 375                 self.push_type_name(inner_type, output);
 376             },
 377             ty::TyRef(_, ty::TypeAndMut { ty: inner_type, mutbl }) => {
 378                 output.push('&');
 379                 if mutbl == hir::MutMutable {
 380                     output.push_str("mut ");
 381                 }
 382
 383                 self.push_type_name(inner_type, output);
 384             },
 385             ty::TyArray(inner_type, len) => {
 386                 output.push('[');
 387                 self.push_type_name(inner_type, output);
 388                 write!(output, "; {}", len).unwrap();
 389                 output.push(']');
 390             },
 391             ty::TySlice(inner_type) => {
 392                 output.push('[');
 393                 self.push_type_name(inner_type, output);
 394                 output.push(']');
 395             },
 396             ty::TyDynamic(ref trait_data, ..) => {
 397                 if let Some(principal) = trait_data.principal() {
 398                     self.push_def_path(principal.def_id(), output);
 399                     self.push_type_params(principal.skip_binder().substs,
 400                         trait_data.projection_bounds(),
 401                         output);
 402                 }
 403             },
 404             ty::TyFnDef(.., sig) |
 405             ty::TyFnPtr(sig) => {
 406                 if sig.unsafety() == hir::Unsafety::Unsafe {
 407                     output.push_str("unsafe ");
 408                 }
 409
 410                 let abi = sig.abi();
 411                 if abi != ::abi::Abi::Rust {
 412                     output.push_str("extern \"");
 413                     output.push_str(abi.name());
 414                     output.push_str("\" ");
 415                 }
 416
 417                 output.push_str("fn(");
 418
 419                 let sig = self.tcx.erase_late_bound_regions_and_normalize(&sig);
 420
 421                 if !sig.inputs().is_empty() {
 422                     for &parameter_type in sig.inputs() {
 423                         self.push_type_name(parameter_type, output);
 424                         output.push_str(", ");
 425                     }
 426                     output.pop();
 427                     output.pop();
 428                 }
 429
 430                 if sig.variadic {
 431                     if !sig.inputs().is_empty() {
 432                         output.push_str(", ...");
 433                     } else {
 434                         output.push_str("...");
 435                     }
 436                 }
 437
 438                 output.push(')');
 439
 440                 if !sig.output().is_nil() {
 441                     output.push_str(" -> ");
 442                     self.push_type_name(sig.output(), output);
 443                 }
 444             },
 445             ty::TyClosure(def_id, ref closure_substs) => {
 446                 self.push_def_path(def_id, output);
 447                 let generics = self.tcx.generics_of(self.tcx.closure_base_def_id(def_id));
 448                 let substs = closure_substs.substs.truncate_to(self.tcx, generics);
 449                 self.push_type_params(substs, iter::empty(), output);
 450             }
 451             ty::TyError |
 452             ty::TyInfer(_) |
 453             ty::TyProjection(..) |
 454             ty::TyParam(_) |
 455             ty::TyAnon(..) => {
 456                 bug!("DefPathBasedNames: Trying to create type name for \
 457                                          unexpected type: {:?}", t);
 458             }
 459         }
 460     }
 461
 462     pub fn push_def_path(&self,
 463                          def_id: DefId,
 464                          output: &mut String) {
 465         let def_path = self.tcx.def_path(def_id);
 466
 467         // some_crate::
 468         if !(self.omit_local_crate_name && def_id.is_local()) {
 469             output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
 470             output.push_str("::");
 471         }
 472
 473         // foo::bar::ItemName::
 474         for part in self.tcx.def_path(def_id).data {
 475             if self.omit_disambiguators {
 476                 write!(output, "{}::", part.data.as_interned_str()).unwrap();
 477             } else {
 478                 write!(output, "{}[{}]::",
 479                        part.data.as_interned_str(),
 480                        part.disambiguator).unwrap();
 481             }
 482         }
 483
 484         // remove final "::"
 485         output.pop();
 486         output.pop();
 487     }
 488
 489     fn push_type_params<I>(&self,
 490                             substs: &Substs<'tcx>,
 491                             projections: I,
 492                             output: &mut String)
 493         where I: Iterator<Item=ty::PolyExistentialProjection<'tcx>>
 494     {
 495         let mut projections = projections.peekable();
 496         if substs.types().next().is_none() && projections.peek().is_none() {
 497             return;
 498         }
 499
 500         output.push('<');
 501
 502         for type_parameter in substs.types() {
 503             self.push_type_name(type_parameter, output);
 504             output.push_str(", ");
 505         }
 506
 507         for projection in projections {
 508             let projection = projection.skip_binder();
 509             let name = &projection.item_name.as_str();
 510             output.push_str(name);
 511             output.push_str("=");
 512             self.push_type_name(projection.ty, output);
 513             output.push_str(", ");
 514         }
 515
 516         output.pop();
 517         output.pop();
 518
 519         output.push('>');
 520     }
 521
 522     pub fn push_instance_as_string(&self,
 523                                    instance: Instance<'tcx>,
 524                                    output: &mut String) {
 525         self.push_def_path(instance.def_id(), output);
 526         self.push_type_params(instance.substs, iter::empty(), output);
 527     }
 528 }