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