src/librustc_trans/callee.rs

   1 // Copyright 2012 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 //! Handles translation of callees as well as other call-related
  12 //! things.  Callees are a superset of normal rust values and sometimes
  13 //! have different representations.  In particular, top-level fn items
  14 //! and methods are represented as just a fn ptr and not a full
  15 //! closure.
  16
  17 pub use self::CalleeData::*;
  18 pub use self::CallArgs::*;
  19
  20 use arena::TypedArena;
  21 use back::symbol_names;
  22 use llvm::{self, ValueRef, get_params};
  23 use middle::cstore::LOCAL_CRATE;
  24 use rustc::hir::def_id::DefId;
  25 use rustc::ty::subst;
  26 use rustc::traits;
  27 use rustc::hir::map as hir_map;
  28 use abi::{Abi, FnType};
  29 use adt;
  30 use attributes;
  31 use base;
  32 use base::*;
  33 use build::*;
  34 use cleanup;
  35 use cleanup::CleanupMethods;
  36 use closure;
  37 use common::{self, Block, Result, CrateContext, FunctionContext, C_undef};
  38 use consts;
  39 use datum::*;
  40 use debuginfo::DebugLoc;
  41 use declare;
  42 use expr;
  43 use glue;
  44 use inline;
  45 use intrinsic;
  46 use machine::llalign_of_min;
  47 use meth;
  48 use monomorphize::{self, Instance};
  49 use type_::Type;
  50 use type_of;
  51 use value::Value;
  52 use Disr;
  53 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
  54 use rustc::hir;
  55
  56 use syntax_pos::DUMMY_SP;
  57 use errors;
  58 use syntax::ptr::P;
  59
  60 #[derive(Debug)]
  61 pub enum CalleeData {
  62     /// Constructor for enum variant/tuple-like-struct.
  63     NamedTupleConstructor(Disr),
  64
  65     /// Function pointer.
  66     Fn(ValueRef),
  67
  68     Intrinsic,
  69
  70     /// Trait object found in the vtable at that index.
  71     Virtual(usize)
  72 }
  73
  74 #[derive(Debug)]
  75 pub struct Callee<'tcx> {
  76     pub data: CalleeData,
  77     pub ty: Ty<'tcx>
  78 }
  79
  80 impl<'tcx> Callee<'tcx> {
  81     /// Function pointer.
  82     pub fn ptr(datum: Datum<'tcx, Rvalue>) -> Callee<'tcx> {
  83         Callee {
  84             data: Fn(datum.val),
  85             ty: datum.ty
  86         }
  87     }
  88
  89     /// Trait or impl method call.
  90     pub fn method_call<'blk>(bcx: Block<'blk, 'tcx>,
  91                              method_call: ty::MethodCall)
  92                              -> Callee<'tcx> {
  93         let method = bcx.tcx().tables.borrow().method_map[&method_call];
  94         Callee::method(bcx, method)
  95     }
  96
  97     /// Trait or impl method.
  98     pub fn method<'blk>(bcx: Block<'blk, 'tcx>,
  99                         method: ty::MethodCallee<'tcx>) -> Callee<'tcx> {
 100         let substs = bcx.fcx.monomorphize(&method.substs);
 101         Callee::def(bcx.ccx(), method.def_id, substs)
 102     }
 103
 104     /// Function or method definition.
 105     pub fn def<'a>(ccx: &CrateContext<'a, 'tcx>,
 106                    def_id: DefId,
 107                    substs: &'tcx subst::Substs<'tcx>)
 108                    -> Callee<'tcx> {
 109         let tcx = ccx.tcx();
 110
 111         if substs.self_ty().is_some() {
 112             // Only trait methods can have a Self parameter.
 113             return Callee::trait_method(ccx, def_id, substs);
 114         }
 115
 116         let maybe_node_id = inline::get_local_instance(ccx, def_id)
 117             .and_then(|def_id| tcx.map.as_local_node_id(def_id));
 118         let maybe_ast_node = maybe_node_id.and_then(|node_id| {
 119             tcx.map.find(node_id)
 120         });
 121
 122         let data = match maybe_ast_node {
 123             Some(hir_map::NodeStructCtor(_)) => {
 124                 NamedTupleConstructor(Disr(0))
 125             }
 126             Some(hir_map::NodeVariant(_)) => {
 127                 let vinfo = common::inlined_variant_def(ccx, maybe_node_id.unwrap());
 128                 NamedTupleConstructor(Disr::from(vinfo.disr_val))
 129             }
 130             Some(hir_map::NodeForeignItem(fi)) if {
 131                 let abi = tcx.map.get_foreign_abi(fi.id);
 132                 abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic
 133             } => Intrinsic,
 134
 135             _ => return Callee::ptr(get_fn(ccx, def_id, substs))
 136         };
 137
 138         Callee {
 139             data: data,
 140             ty: def_ty(tcx, def_id, substs)
 141         }
 142     }
 143
 144     /// Trait method, which has to be resolved to an impl method.
 145     pub fn trait_method<'a>(ccx: &CrateContext<'a, 'tcx>,
 146                             def_id: DefId,
 147                             substs: &'tcx subst::Substs<'tcx>)
 148                             -> Callee<'tcx> {
 149         let tcx = ccx.tcx();
 150
 151         let method_item = tcx.impl_or_trait_item(def_id);
 152         let trait_id = method_item.container().id();
 153         let trait_ref = ty::Binder(substs.to_trait_ref(tcx, trait_id));
 154         let trait_ref = tcx.normalize_associated_type(&trait_ref);
 155         match common::fulfill_obligation(ccx.shared(), DUMMY_SP, trait_ref) {
 156             traits::VtableImpl(vtable_impl) => {
 157                 let impl_did = vtable_impl.impl_def_id;
 158                 let mname = tcx.item_name(def_id);
 159                 // create a concatenated set of substitutions which includes
 160                 // those from the impl and those from the method:
 161                 let impl_substs = vtable_impl.substs.with_method_from(&substs);
 162                 let substs = tcx.mk_substs(impl_substs);
 163                 let mth = meth::get_impl_method(tcx, impl_did, substs, mname);
 164
 165                 // Translate the function, bypassing Callee::def.
 166                 // That is because default methods have the same ID as the
 167                 // trait method used to look up the impl method that ended
 168                 // up here, so calling Callee::def would infinitely recurse.
 169                 Callee::ptr(get_fn(ccx, mth.method.def_id, mth.substs))
 170             }
 171             traits::VtableClosure(vtable_closure) => {
 172                 // The substitutions should have no type parameters remaining
 173                 // after passing through fulfill_obligation
 174                 let trait_closure_kind = tcx.lang_items.fn_trait_kind(trait_id).unwrap();
 175                 let llfn = closure::trans_closure_method(ccx,
 176                                                          vtable_closure.closure_def_id,
 177                                                          vtable_closure.substs,
 178                                                          trait_closure_kind);
 179
 180                 let method_ty = def_ty(tcx, def_id, substs);
 181                 let fn_ptr_ty = match method_ty.sty {
 182                     ty::TyFnDef(_, _, fty) => tcx.mk_fn_ptr(fty),
 183                     _ => bug!("expected fn item type, found {}",
 184                               method_ty)
 185                 };
 186                 Callee::ptr(immediate_rvalue(llfn, fn_ptr_ty))
 187             }
 188             traits::VtableFnPointer(vtable_fn_pointer) => {
 189                 let trait_closure_kind = tcx.lang_items.fn_trait_kind(trait_id).unwrap();
 190                 let llfn = trans_fn_pointer_shim(ccx, trait_closure_kind, vtable_fn_pointer.fn_ty);
 191
 192                 let method_ty = def_ty(tcx, def_id, substs);
 193                 let fn_ptr_ty = match method_ty.sty {
 194                     ty::TyFnDef(_, _, fty) => tcx.mk_fn_ptr(fty),
 195                     _ => bug!("expected fn item type, found {}",
 196                               method_ty)
 197                 };
 198                 Callee::ptr(immediate_rvalue(llfn, fn_ptr_ty))
 199             }
 200             traits::VtableObject(ref data) => {
 201                 Callee {
 202                     data: Virtual(tcx.get_vtable_index_of_object_method(data, def_id)),
 203                     ty: def_ty(tcx, def_id, substs)
 204                 }
 205             }
 206             vtable => {
 207                 bug!("resolved vtable bad vtable {:?} in trans", vtable);
 208             }
 209         }
 210     }
 211
 212     /// Get the abi::FnType for a direct call. Mainly deals with the fact
 213     /// that a Virtual call doesn't take the vtable, like its shim does.
 214     /// The extra argument types are for variadic (extern "C") functions.
 215     pub fn direct_fn_type<'a>(&self, ccx: &CrateContext<'a, 'tcx>,
 216                               extra_args: &[Ty<'tcx>]) -> FnType {
 217         let abi = self.ty.fn_abi();
 218         let sig = ccx.tcx().erase_late_bound_regions(self.ty.fn_sig());
 219         let sig = ccx.tcx().normalize_associated_type(&sig);
 220         let mut fn_ty = FnType::unadjusted(ccx, abi, &sig, extra_args);
 221         if let Virtual(_) = self.data {
 222             // Don't pass the vtable, it's not an argument of the virtual fn.
 223             fn_ty.args[1].ignore();
 224         }
 225         fn_ty.adjust_for_abi(ccx, abi, &sig);
 226         fn_ty
 227     }
 228
 229     /// This behemoth of a function translates function calls. Unfortunately, in
 230     /// order to generate more efficient LLVM output at -O0, it has quite a complex
 231     /// signature (refactoring this into two functions seems like a good idea).
 232     ///
 233     /// In particular, for lang items, it is invoked with a dest of None, and in
 234     /// that case the return value contains the result of the fn. The lang item must
 235     /// not return a structural type or else all heck breaks loose.
 236     ///
 237     /// For non-lang items, `dest` is always Some, and hence the result is written
 238     /// into memory somewhere. Nonetheless we return the actual return value of the
 239     /// function.
 240     pub fn call<'a, 'blk>(self, bcx: Block<'blk, 'tcx>,
 241                           debug_loc: DebugLoc,
 242                           args: CallArgs<'a, 'tcx>,
 243                           dest: Option<expr::Dest>)
 244                           -> Result<'blk, 'tcx> {
 245         trans_call_inner(bcx, debug_loc, self, args, dest)
 246     }
 247
 248     /// Turn the callee into a function pointer.
 249     pub fn reify<'a>(self, ccx: &CrateContext<'a, 'tcx>)
 250                      -> Datum<'tcx, Rvalue> {
 251         let fn_ptr_ty = match self.ty.sty {
 252             ty::TyFnDef(_, _, f) => ccx.tcx().mk_fn_ptr(f),
 253             _ => self.ty
 254         };
 255         match self.data {
 256             Fn(llfn) => {
 257                 immediate_rvalue(llfn, fn_ptr_ty)
 258             }
 259             Virtual(idx) => {
 260                 let llfn = meth::trans_object_shim(ccx, self.ty, idx);
 261                 immediate_rvalue(llfn, fn_ptr_ty)
 262             }
 263             NamedTupleConstructor(_) => match self.ty.sty {
 264                 ty::TyFnDef(def_id, substs, _) => {
 265                     return get_fn(ccx, def_id, substs);
 266                 }
 267                 _ => bug!("expected fn item type, found {}", self.ty)
 268             },
 269             Intrinsic => bug!("intrinsic {} getting reified", self.ty)
 270         }
 271     }
 272 }
 273
 274 /// Given a DefId and some Substs, produces the monomorphic item type.
 275 fn def_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 276                     def_id: DefId,
 277                     substs: &'tcx subst::Substs<'tcx>)
 278                     -> Ty<'tcx> {
 279     let ty = tcx.lookup_item_type(def_id).ty;
 280     monomorphize::apply_param_substs(tcx, substs, &ty)
 281 }
 282
 283 /// Translates an adapter that implements the `Fn` trait for a fn
 284 /// pointer. This is basically the equivalent of something like:
 285 ///
 286 /// ```
 287 /// impl<'a> Fn(&'a int) -> &'a int for fn(&int) -> &int {
 288 ///     extern "rust-abi" fn call(&self, args: (&'a int,)) -> &'a int {
 289 ///         (*self)(args.0)
 290 ///     }
 291 /// }
 292 /// ```
 293 ///
 294 /// but for the bare function type given.
 295 pub fn trans_fn_pointer_shim<'a, 'tcx>(
 296     ccx: &'a CrateContext<'a, 'tcx>,
 297     closure_kind: ty::ClosureKind,
 298     bare_fn_ty: Ty<'tcx>)
 299     -> ValueRef
 300 {
 301     let _icx = push_ctxt("trans_fn_pointer_shim");
 302     let tcx = ccx.tcx();
 303
 304     // Normalize the type for better caching.
 305     let bare_fn_ty = tcx.erase_regions(&bare_fn_ty);
 306
 307     // If this is an impl of `Fn` or `FnMut` trait, the receiver is `&self`.
 308     let is_by_ref = match closure_kind {
 309         ty::ClosureKind::Fn | ty::ClosureKind::FnMut => true,
 310         ty::ClosureKind::FnOnce => false,
 311     };
 312
 313     let llfnpointer = match bare_fn_ty.sty {
 314         ty::TyFnDef(def_id, substs, _) => {
 315             // Function definitions have to be turned into a pointer.
 316             let llfn = Callee::def(ccx, def_id, substs).reify(ccx).val;
 317             if !is_by_ref {
 318                 // A by-value fn item is ignored, so the shim has
 319                 // the same signature as the original function.
 320                 return llfn;
 321             }
 322             Some(llfn)
 323         }
 324         _ => None
 325     };
 326
 327     let bare_fn_ty_maybe_ref = if is_by_ref {
 328         tcx.mk_imm_ref(tcx.mk_region(ty::ReErased), bare_fn_ty)
 329     } else {
 330         bare_fn_ty
 331     };
 332
 333     // Check if we already trans'd this shim.
 334     match ccx.fn_pointer_shims().borrow().get(&bare_fn_ty_maybe_ref) {
 335         Some(&llval) => { return llval; }
 336         None => { }
 337     }
 338
 339     debug!("trans_fn_pointer_shim(bare_fn_ty={:?})",
 340            bare_fn_ty);
 341
 342     // Construct the "tuply" version of `bare_fn_ty`. It takes two arguments: `self`,
 343     // which is the fn pointer, and `args`, which is the arguments tuple.
 344     let sig = match bare_fn_ty.sty {
 345         ty::TyFnDef(_, _,
 346                     &ty::BareFnTy { unsafety: hir::Unsafety::Normal,
 347                                     abi: Abi::Rust,
 348                                     ref sig }) |
 349         ty::TyFnPtr(&ty::BareFnTy { unsafety: hir::Unsafety::Normal,
 350                                     abi: Abi::Rust,
 351                                     ref sig }) => sig,
 352
 353         _ => {
 354             bug!("trans_fn_pointer_shim invoked on invalid type: {}",
 355                  bare_fn_ty);
 356         }
 357     };
 358     let sig = tcx.erase_late_bound_regions(sig);
 359     let sig = ccx.tcx().normalize_associated_type(&sig);
 360     let tuple_input_ty = tcx.mk_tup(sig.inputs.to_vec());
 361     let sig = ty::FnSig {
 362         inputs: vec![bare_fn_ty_maybe_ref,
 363                      tuple_input_ty],
 364         output: sig.output,
 365         variadic: false
 366     };
 367     let fn_ty = FnType::new(ccx, Abi::RustCall, &sig, &[]);
 368     let tuple_fn_ty = tcx.mk_fn_ptr(tcx.mk_bare_fn(ty::BareFnTy {
 369         unsafety: hir::Unsafety::Normal,
 370         abi: Abi::RustCall,
 371         sig: ty::Binder(sig)
 372     }));
 373     debug!("tuple_fn_ty: {:?}", tuple_fn_ty);
 374
 375     //
 376     let function_name =
 377         symbol_names::internal_name_from_type_and_suffix(ccx,
 378                                                          bare_fn_ty,
 379                                                          "fn_pointer_shim");
 380     let llfn = declare::define_internal_fn(ccx, &function_name, tuple_fn_ty);
 381     attributes::set_frame_pointer_elimination(ccx, llfn);
 382     //
 383     let (block_arena, fcx): (TypedArena<_>, FunctionContext);
 384     block_arena = TypedArena::new();
 385     fcx = FunctionContext::new(ccx, llfn, fn_ty, None, &block_arena);
 386     let mut bcx = fcx.init(false, None);
 387
 388     let llargs = get_params(fcx.llfn);
 389
 390     let self_idx = fcx.fn_ty.ret.is_indirect() as usize;
 391     let llfnpointer = llfnpointer.unwrap_or_else(|| {
 392         // the first argument (`self`) will be ptr to the fn pointer
 393         if is_by_ref {
 394             Load(bcx, llargs[self_idx])
 395         } else {
 396             llargs[self_idx]
 397         }
 398     });
 399
 400     assert!(!fcx.needs_ret_allocas);
 401
 402     let dest = fcx.llretslotptr.get().map(|_|
 403         expr::SaveIn(fcx.get_ret_slot(bcx, "ret_slot"))
 404     );
 405
 406     let callee = Callee {
 407         data: Fn(llfnpointer),
 408         ty: bare_fn_ty
 409     };
 410     bcx = callee.call(bcx, DebugLoc::None, ArgVals(&llargs[(self_idx + 1)..]), dest).bcx;
 411
 412     fcx.finish(bcx, DebugLoc::None);
 413
 414     ccx.fn_pointer_shims().borrow_mut().insert(bare_fn_ty_maybe_ref, llfn);
 415
 416     llfn
 417 }
 418
 419 /// Translates a reference to a fn/method item, monomorphizing and
 420 /// inlining as it goes.
 421 ///
 422 /// # Parameters
 423 ///
 424 /// - `ccx`: the crate context
 425 /// - `def_id`: def id of the fn or method item being referenced
 426 /// - `substs`: values for each of the fn/method's parameters
 427 fn get_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 428                     def_id: DefId,
 429                     substs: &'tcx subst::Substs<'tcx>)
 430                     -> Datum<'tcx, Rvalue> {
 431     let tcx = ccx.tcx();
 432
 433     debug!("get_fn(def_id={:?}, substs={:?})", def_id, substs);
 434
 435     assert!(!substs.types.needs_infer());
 436     assert!(!substs.types.has_escaping_regions());
 437
 438     // Check whether this fn has an inlined copy and, if so, redirect
 439     // def_id to the local id of the inlined copy.
 440     let def_id = inline::maybe_instantiate_inline(ccx, def_id);
 441
 442     fn is_named_tuple_constructor(tcx: TyCtxt, def_id: DefId) -> bool {
 443         let node_id = match tcx.map.as_local_node_id(def_id) {
 444             Some(n) => n,
 445             None => { return false; }
 446         };
 447         let map_node = errors::expect(
 448             &tcx.sess.diagnostic(),
 449             tcx.map.find(node_id),
 450             || "local item should be in ast map".to_string());
 451
 452         match map_node {
 453             hir_map::NodeVariant(v) => {
 454                 v.node.data.is_tuple()
 455             }
 456             hir_map::NodeStructCtor(_) => true,
 457             _ => false
 458         }
 459     }
 460     let must_monomorphise =
 461         !substs.types.is_empty() || is_named_tuple_constructor(tcx, def_id);
 462
 463     debug!("get_fn({:?}) must_monomorphise: {}",
 464            def_id, must_monomorphise);
 465
 466     // Create a monomorphic version of generic functions
 467     if must_monomorphise {
 468         // Should be either intra-crate or inlined.
 469         assert_eq!(def_id.krate, LOCAL_CRATE);
 470
 471         let substs = tcx.mk_substs(substs.clone().erase_regions());
 472         let (val, fn_ty) = monomorphize::monomorphic_fn(ccx, def_id, substs);
 473         let fn_ptr_ty = match fn_ty.sty {
 474             ty::TyFnDef(_, _, fty) => {
 475                 // Create a fn pointer with the substituted signature.
 476                 tcx.mk_fn_ptr(fty)
 477             }
 478             _ => bug!("expected fn item type, found {}", fn_ty)
 479         };
 480         assert_eq!(type_of::type_of(ccx, fn_ptr_ty), common::val_ty(val));
 481         return immediate_rvalue(val, fn_ptr_ty);
 482     }
 483
 484     // Find the actual function pointer.
 485     let ty = ccx.tcx().lookup_item_type(def_id).ty;
 486     let fn_ptr_ty = match ty.sty {
 487         ty::TyFnDef(_, _, ref fty) => {
 488             // Create a fn pointer with the normalized signature.
 489             tcx.mk_fn_ptr(tcx.normalize_associated_type(fty))
 490         }
 491         _ => bug!("expected fn item type, found {}", ty)
 492     };
 493
 494     let instance = Instance::mono(ccx.shared(), def_id);
 495     if let Some(&llfn) = ccx.instances().borrow().get(&instance) {
 496         return immediate_rvalue(llfn, fn_ptr_ty);
 497     }
 498
 499     let local_id = ccx.tcx().map.as_local_node_id(def_id);
 500     let local_item = match local_id.and_then(|id| tcx.map.find(id)) {
 501         Some(hir_map::NodeItem(&hir::Item {
 502             span, node: hir::ItemFn(..), ..
 503         })) |
 504         Some(hir_map::NodeTraitItem(&hir::TraitItem {
 505             span, node: hir::MethodTraitItem(_, Some(_)), ..
 506         })) |
 507         Some(hir_map::NodeImplItem(&hir::ImplItem {
 508             span, node: hir::ImplItemKind::Method(..), ..
 509         })) => {
 510             Some(span)
 511         }
 512         _ => None
 513     };
 514
 515     // This is subtle and surprising, but sometimes we have to bitcast
 516     // the resulting fn pointer.  The reason has to do with external
 517     // functions.  If you have two crates that both bind the same C
 518     // library, they may not use precisely the same types: for
 519     // example, they will probably each declare their own structs,
 520     // which are distinct types from LLVM's point of view (nominal
 521     // types).
 522     //
 523     // Now, if those two crates are linked into an application, and
 524     // they contain inlined code, you can wind up with a situation
 525     // where both of those functions wind up being loaded into this
 526     // application simultaneously. In that case, the same function
 527     // (from LLVM's point of view) requires two types. But of course
 528     // LLVM won't allow one function to have two types.
 529     //
 530     // What we currently do, therefore, is declare the function with
 531     // one of the two types (whichever happens to come first) and then
 532     // bitcast as needed when the function is referenced to make sure
 533     // it has the type we expect.
 534     //
 535     // This can occur on either a crate-local or crate-external
 536     // reference. It also occurs when testing libcore and in some
 537     // other weird situations. Annoying.
 538
 539     let sym = instance.symbol_name(ccx.shared());
 540     let llptrty = type_of::type_of(ccx, fn_ptr_ty);
 541     let llfn = if let Some(llfn) = declare::get_declared_value(ccx, &sym) {
 542         if let Some(span) = local_item {
 543             if declare::get_defined_value(ccx, &sym).is_some() {
 544                 ccx.sess().span_fatal(span,
 545                     &format!("symbol `{}` is already defined", sym));
 546             }
 547         }
 548
 549         if common::val_ty(llfn) != llptrty {
 550             if local_item.is_some() {
 551                 bug!("symbol `{}` previously declared as {:?}, now wanted as {:?}",
 552                      sym, Value(llfn), llptrty);
 553             }
 554             debug!("get_fn: casting {:?} to {:?}", llfn, llptrty);
 555             consts::ptrcast(llfn, llptrty)
 556         } else {
 557             debug!("get_fn: not casting pointer!");
 558             llfn
 559         }
 560     } else {
 561         let llfn = declare::declare_fn(ccx, &sym, ty);
 562         assert_eq!(common::val_ty(llfn), llptrty);
 563         debug!("get_fn: not casting pointer!");
 564
 565         let attrs = ccx.tcx().get_attrs(def_id);
 566         attributes::from_fn_attrs(ccx, &attrs, llfn);
 567         if local_item.is_some() {
 568             // FIXME(eddyb) Doubt all extern fn should allow unwinding.
 569             attributes::unwind(llfn, true);
 570         }
 571
 572         llfn
 573     };
 574
 575     ccx.instances().borrow_mut().insert(instance, llfn);
 576
 577     immediate_rvalue(llfn, fn_ptr_ty)
 578 }
 579
 580 // ______________________________________________________________________
 581 // Translating calls
 582
 583 fn trans_call_inner<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
 584                                     debug_loc: DebugLoc,
 585                                     callee: Callee<'tcx>,
 586                                     args: CallArgs<'a, 'tcx>,
 587                                     dest: Option<expr::Dest>)
 588                                     -> Result<'blk, 'tcx> {
 589     // Introduce a temporary cleanup scope that will contain cleanups
 590     // for the arguments while they are being evaluated. The purpose
 591     // this cleanup is to ensure that, should a panic occur while
 592     // evaluating argument N, the values for arguments 0...N-1 are all
 593     // cleaned up. If no panic occurs, the values are handed off to
 594     // the callee, and hence none of the cleanups in this temporary
 595     // scope will ever execute.
 596     let fcx = bcx.fcx;
 597     let ccx = fcx.ccx;
 598
 599     let abi = callee.ty.fn_abi();
 600     let sig = callee.ty.fn_sig();
 601     let output = bcx.tcx().erase_late_bound_regions(&sig.output());
 602     let output = bcx.tcx().normalize_associated_type(&output);
 603
 604     let extra_args = match args {
 605         ArgExprs(args) if abi != Abi::RustCall => {
 606             args[sig.0.inputs.len()..].iter().map(|expr| {
 607                 common::expr_ty_adjusted(bcx, expr)
 608             }).collect()
 609         }
 610         _ => vec![]
 611     };
 612     let fn_ty = callee.direct_fn_type(ccx, &extra_args);
 613
 614     let mut callee = match callee.data {
 615         Intrinsic => {
 616             assert!(abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic);
 617             assert!(dest.is_some());
 618
 619             return intrinsic::trans_intrinsic_call(bcx, callee.ty, &fn_ty,
 620                                                    args, dest.unwrap(),
 621                                                    debug_loc);
 622         }
 623         NamedTupleConstructor(disr) => {
 624             assert!(dest.is_some());
 625
 626             return base::trans_named_tuple_constructor(bcx,
 627                                                        callee.ty,
 628                                                        disr,
 629                                                        args,
 630                                                        dest.unwrap(),
 631                                                        debug_loc);
 632         }
 633         f => f
 634     };
 635
 636     // Generate a location to store the result. If the user does
 637     // not care about the result, just make a stack slot.
 638     let opt_llretslot = dest.and_then(|dest| match dest {
 639         expr::SaveIn(dst) => Some(dst),
 640         expr::Ignore => {
 641             let needs_drop = || match output {
 642                 ty::FnConverging(ret_ty) => bcx.fcx.type_needs_drop(ret_ty),
 643                 ty::FnDiverging => false
 644             };
 645             if fn_ty.ret.is_indirect() || fn_ty.ret.cast.is_some() || needs_drop() {
 646                 // Push the out-pointer if we use an out-pointer for this
 647                 // return type, otherwise push "undef".
 648                 if fn_ty.ret.is_ignore() {
 649                     Some(C_undef(fn_ty.ret.original_ty.ptr_to()))
 650                 } else {
 651                     let llresult = alloca(bcx, fn_ty.ret.original_ty, "__llret");
 652                     call_lifetime_start(bcx, llresult);
 653                     Some(llresult)
 654                 }
 655             } else {
 656                 None
 657             }
 658         }
 659     });
 660
 661     // If there no destination, return must be direct, with no cast.
 662     if opt_llretslot.is_none() {
 663         assert!(!fn_ty.ret.is_indirect() && fn_ty.ret.cast.is_none());
 664     }
 665
 666     let mut llargs = Vec::new();
 667
 668     if fn_ty.ret.is_indirect() {
 669         let mut llretslot = opt_llretslot.unwrap();
 670         if let Some(ty) = fn_ty.ret.cast {
 671             llretslot = PointerCast(bcx, llretslot, ty.ptr_to());
 672         }
 673         llargs.push(llretslot);
 674     }
 675
 676     let arg_cleanup_scope = fcx.push_custom_cleanup_scope();
 677     bcx = trans_args(bcx, abi, &fn_ty, &mut callee, args, &mut llargs,
 678                      cleanup::CustomScope(arg_cleanup_scope));
 679     fcx.scopes.borrow_mut().last_mut().unwrap().drop_non_lifetime_clean();
 680
 681     let llfn = match callee {
 682         Fn(f) => f,
 683         _ => bug!("expected fn pointer callee, found {:?}", callee)
 684     };
 685
 686     let (llret, mut bcx) = base::invoke(bcx, llfn, &llargs, debug_loc);
 687     if !bcx.unreachable.get() {
 688         fn_ty.apply_attrs_callsite(llret);
 689
 690         // If the function we just called does not use an outpointer,
 691         // store the result into the rust outpointer. Cast the outpointer
 692         // type to match because some ABIs will use a different type than
 693         // the Rust type. e.g., a {u32,u32} struct could be returned as
 694         // u64.
 695         if !fn_ty.ret.is_indirect() {
 696             if let Some(llretslot) = opt_llretslot {
 697                 fn_ty.ret.store(&bcx.build(), llret, llretslot);
 698             }
 699         }
 700     }
 701
 702     fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_cleanup_scope);
 703
 704     // If the caller doesn't care about the result of this fn call,
 705     // drop the temporary slot we made.
 706     match (dest, opt_llretslot, output) {
 707         (Some(expr::Ignore), Some(llretslot), ty::FnConverging(ret_ty)) => {
 708             // drop the value if it is not being saved.
 709             bcx = glue::drop_ty(bcx, llretslot, ret_ty, debug_loc);
 710             call_lifetime_end(bcx, llretslot);
 711         }
 712         _ => {}
 713     }
 714
 715     if output == ty::FnDiverging {
 716         Unreachable(bcx);
 717     }
 718
 719     Result::new(bcx, llret)
 720 }
 721
 722 pub enum CallArgs<'a, 'tcx> {
 723     /// Supply value of arguments as a list of expressions that must be
 724     /// translated. This is used in the common case of `foo(bar, qux)`.
 725     ArgExprs(&'a [P<hir::Expr>]),
 726
 727     /// Supply value of arguments as a list of LLVM value refs; frequently
 728     /// used with lang items and so forth, when the argument is an internal
 729     /// value.
 730     ArgVals(&'a [ValueRef]),
 731
 732     /// For overloaded operators: `(lhs, Option(rhs))`.
 733     /// `lhs` is the left-hand-side and `rhs` is the datum
 734     /// of the right-hand-side argument (if any).
 735     ArgOverloadedOp(Datum<'tcx, Expr>, Option<Datum<'tcx, Expr>>),
 736
 737     /// Supply value of arguments as a list of expressions that must be
 738     /// translated, for overloaded call operators.
 739     ArgOverloadedCall(Vec<&'a hir::Expr>),
 740 }
 741
 742 fn trans_args_under_call_abi<'blk, 'tcx>(
 743                              mut bcx: Block<'blk, 'tcx>,
 744                              arg_exprs: &[P<hir::Expr>],
 745                              callee: &mut CalleeData,
 746                              fn_ty: &FnType,
 747                              llargs: &mut Vec<ValueRef>,
 748                              arg_cleanup_scope: cleanup::ScopeId)
 749                              -> Block<'blk, 'tcx>
 750 {
 751     let mut arg_idx = 0;
 752
 753     // Translate the `self` argument first.
 754     let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &arg_exprs[0]));
 755     bcx = trans_arg_datum(bcx,
 756                           arg_datum,
 757                           callee, fn_ty, &mut arg_idx,
 758                           arg_cleanup_scope,
 759                           llargs);
 760
 761     // Now untuple the rest of the arguments.
 762     let tuple_expr = &arg_exprs[1];
 763     let tuple_type = common::node_id_type(bcx, tuple_expr.id);
 764
 765     match tuple_type.sty {
 766         ty::TyTuple(ref field_types) => {
 767             let tuple_datum = unpack_datum!(bcx,
 768                                             expr::trans(bcx, &tuple_expr));
 769             let tuple_lvalue_datum =
 770                 unpack_datum!(bcx,
 771                               tuple_datum.to_lvalue_datum(bcx,
 772                                                           "args",
 773                                                           tuple_expr.id));
 774             let repr = adt::represent_type(bcx.ccx(), tuple_type);
 775             let repr_ptr = &repr;
 776             for (i, field_type) in field_types.iter().enumerate() {
 777                 let arg_datum = tuple_lvalue_datum.get_element(
 778                     bcx,
 779                     field_type,
 780                     |srcval| {
 781                         adt::trans_field_ptr(bcx, repr_ptr, srcval, Disr(0), i)
 782                     }).to_expr_datum();
 783                 bcx = trans_arg_datum(bcx,
 784                                       arg_datum,
 785                                       callee, fn_ty, &mut arg_idx,
 786                                       arg_cleanup_scope,
 787                                       llargs);
 788             }
 789         }
 790         _ => {
 791             span_bug!(tuple_expr.span,
 792                       "argument to `.call()` wasn't a tuple?!")
 793         }
 794     };
 795
 796     bcx
 797 }
 798
 799 pub fn trans_args<'a, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 800                                   abi: Abi,
 801                                   fn_ty: &FnType,
 802                                   callee: &mut CalleeData,
 803                                   args: CallArgs<'a, 'tcx>,
 804                                   llargs: &mut Vec<ValueRef>,
 805                                   arg_cleanup_scope: cleanup::ScopeId)
 806                                   -> Block<'blk, 'tcx> {
 807     debug!("trans_args(abi={})", abi);
 808
 809     let _icx = push_ctxt("trans_args");
 810
 811     let mut bcx = bcx;
 812     let mut arg_idx = 0;
 813
 814     // First we figure out the caller's view of the types of the arguments.
 815     // This will be needed if this is a generic call, because the callee has
 816     // to cast her view of the arguments to the caller's view.
 817     match args {
 818         ArgExprs(arg_exprs) => {
 819             if abi == Abi::RustCall {
 820                 // This is only used for direct calls to the `call`,
 821                 // `call_mut` or `call_once` functions.
 822                 return trans_args_under_call_abi(bcx,
 823                                                  arg_exprs, callee, fn_ty,
 824                                                  llargs,
 825                                                  arg_cleanup_scope)
 826             }
 827
 828             for arg_expr in arg_exprs {
 829                 let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &arg_expr));
 830                 bcx = trans_arg_datum(bcx,
 831                                       arg_datum,
 832                                       callee, fn_ty, &mut arg_idx,
 833                                       arg_cleanup_scope,
 834                                       llargs);
 835             }
 836         }
 837         ArgOverloadedCall(arg_exprs) => {
 838             for expr in arg_exprs {
 839                 let arg_datum =
 840                     unpack_datum!(bcx, expr::trans(bcx, expr));
 841                 bcx = trans_arg_datum(bcx,
 842                                       arg_datum,
 843                                       callee, fn_ty, &mut arg_idx,
 844                                       arg_cleanup_scope,
 845                                       llargs);
 846             }
 847         }
 848         ArgOverloadedOp(lhs, rhs) => {
 849             bcx = trans_arg_datum(bcx, lhs,
 850                                   callee, fn_ty, &mut arg_idx,
 851                                   arg_cleanup_scope,
 852                                   llargs);
 853
 854             if let Some(rhs) = rhs {
 855                 bcx = trans_arg_datum(bcx, rhs,
 856                                       callee, fn_ty, &mut arg_idx,
 857                                       arg_cleanup_scope,
 858                                       llargs);
 859             }
 860         }
 861         ArgVals(vs) => {
 862             match *callee {
 863                 Virtual(idx) => {
 864                     llargs.push(vs[0]);
 865
 866                     let fn_ptr = meth::get_virtual_method(bcx, vs[1], idx);
 867                     let llty = fn_ty.llvm_type(bcx.ccx()).ptr_to();
 868                     *callee = Fn(PointerCast(bcx, fn_ptr, llty));
 869                     llargs.extend_from_slice(&vs[2..]);
 870                 }
 871                 _ => llargs.extend_from_slice(vs)
 872             }
 873         }
 874     }
 875
 876     bcx
 877 }
 878
 879 fn trans_arg_datum<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 880                                arg_datum: Datum<'tcx, Expr>,
 881                                callee: &mut CalleeData,
 882                                fn_ty: &FnType,
 883                                next_idx: &mut usize,
 884                                arg_cleanup_scope: cleanup::ScopeId,
 885                                llargs: &mut Vec<ValueRef>)
 886                                -> Block<'blk, 'tcx> {
 887     let _icx = push_ctxt("trans_arg_datum");
 888     let mut bcx = bcx;
 889
 890     debug!("trans_arg_datum({:?})", arg_datum);
 891
 892     let arg = &fn_ty.args[*next_idx];
 893     *next_idx += 1;
 894
 895     // Fill padding with undef value, where applicable.
 896     if let Some(ty) = arg.pad {
 897         llargs.push(C_undef(ty));
 898     }
 899
 900     // Determine whether we want a by-ref datum even if not appropriate.
 901     let want_by_ref = arg.is_indirect() || arg.cast.is_some();
 902
 903     let fat_ptr = common::type_is_fat_ptr(bcx.tcx(), arg_datum.ty);
 904     let (by_ref, val) = if fat_ptr && !bcx.fcx.type_needs_drop(arg_datum.ty) {
 905         (true, arg_datum.val)
 906     } else {
 907         // Make this an rvalue, since we are going to be
 908         // passing ownership.
 909         let arg_datum = unpack_datum!(
 910             bcx, arg_datum.to_rvalue_datum(bcx, "arg"));
 911
 912         // Now that arg_datum is owned, get it into the appropriate
 913         // mode (ref vs value).
 914         let arg_datum = unpack_datum!(bcx, if want_by_ref {
 915             arg_datum.to_ref_datum(bcx)
 916         } else {
 917             arg_datum.to_appropriate_datum(bcx)
 918         });
 919
 920         // Technically, ownership of val passes to the callee.
 921         // However, we must cleanup should we panic before the
 922         // callee is actually invoked.
 923         (arg_datum.kind.is_by_ref(),
 924          arg_datum.add_clean(bcx.fcx, arg_cleanup_scope))
 925     };
 926
 927     if arg.is_ignore() {
 928         return bcx;
 929     }
 930
 931     debug!("--- trans_arg_datum passing {:?}", Value(val));
 932
 933     if fat_ptr {
 934         // Fat pointers should be passed without any transformations.
 935         assert!(!arg.is_indirect() && arg.cast.is_none());
 936         llargs.push(Load(bcx, expr::get_dataptr(bcx, val)));
 937
 938         let info_arg = &fn_ty.args[*next_idx];
 939         *next_idx += 1;
 940         assert!(!info_arg.is_indirect() && info_arg.cast.is_none());
 941         let info = Load(bcx, expr::get_meta(bcx, val));
 942
 943         if let Virtual(idx) = *callee {
 944             // We have to grab the fn pointer from the vtable when
 945             // handling the first argument, ensure that here.
 946             assert_eq!(*next_idx, 2);
 947             assert!(info_arg.is_ignore());
 948             let fn_ptr = meth::get_virtual_method(bcx, info, idx);
 949             let llty = fn_ty.llvm_type(bcx.ccx()).ptr_to();
 950             *callee = Fn(PointerCast(bcx, fn_ptr, llty));
 951         } else {
 952             assert!(!info_arg.is_ignore());
 953             llargs.push(info);
 954         }
 955         return bcx;
 956     }
 957
 958     let mut val = val;
 959     if by_ref && !arg.is_indirect() {
 960         // Have to load the argument, maybe while casting it.
 961         if arg.original_ty == Type::i1(bcx.ccx()) {
 962             // We store bools as i8 so we need to truncate to i1.
 963             val = LoadRangeAssert(bcx, val, 0, 2, llvm::False);
 964             val = Trunc(bcx, val, arg.original_ty);
 965         } else if let Some(ty) = arg.cast {
 966             val = Load(bcx, PointerCast(bcx, val, ty.ptr_to()));
 967             if !bcx.unreachable.get() {
 968                 let llalign = llalign_of_min(bcx.ccx(), arg.ty);
 969                 unsafe {
 970                     llvm::LLVMSetAlignment(val, llalign);
 971                 }
 972             }
 973         } else {
 974             val = Load(bcx, val);
 975         }
 976     }
 977
 978     llargs.push(val);
 979     bcx
 980 }