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