src/librustc_trans/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::AutorefArg::*;
  18 pub use self::CalleeData::*;
  19 pub use self::CallArgs::*;
  20
  21 use arena::TypedArena;
  22 use back::link;
  23 use session;
  24 use llvm::ValueRef;
  25 use llvm::get_param;
  26 use llvm;
  27 use metadata::csearch;
  28 use middle::def;
  29 use middle::subst;
  30 use middle::subst::{Subst, Substs};
  31 use trans::adt;
  32 use trans::base;
  33 use trans::base::*;
  34 use trans::build::*;
  35 use trans::callee;
  36 use trans::cleanup;
  37 use trans::cleanup::CleanupMethods;
  38 use trans::closure;
  39 use trans::common::{self, Block, Result, NodeIdAndSpan, ExprId, CrateContext,
  40                     ExprOrMethodCall, FunctionContext, MethodCallKey};
  41 use trans::consts;
  42 use trans::datum::*;
  43 use trans::debuginfo::{DebugLoc, ToDebugLoc};
  44 use trans::declare;
  45 use trans::expr;
  46 use trans::glue;
  47 use trans::inline;
  48 use trans::foreign;
  49 use trans::intrinsic;
  50 use trans::meth;
  51 use trans::monomorphize;
  52 use trans::type_::Type;
  53 use trans::type_of;
  54 use middle::ty::{self, Ty};
  55 use middle::ty::MethodCall;
  56 use util::ppaux::Repr;
  57 use util::ppaux::ty_to_string;
  58
  59 use syntax::abi as synabi;
  60 use syntax::ast;
  61 use syntax::ast_map;
  62 use syntax::ptr::P;
  63
  64 #[derive(Copy, Clone)]
  65 pub struct MethodData {
  66     pub llfn: ValueRef,
  67     pub llself: ValueRef,
  68 }
  69
  70 pub enum CalleeData<'tcx> {
  71     // Constructor for enum variant/tuple-like-struct
  72     // i.e. Some, Ok
  73     NamedTupleConstructor(subst::Substs<'tcx>, ty::Disr),
  74
  75     // Represents a (possibly monomorphized) top-level fn item or method
  76     // item. Note that this is just the fn-ptr and is not a Rust closure
  77     // value (which is a pair).
  78     Fn(/* llfn */ ValueRef),
  79
  80     Intrinsic(ast::NodeId, subst::Substs<'tcx>),
  81
  82     TraitItem(MethodData)
  83 }
  84
  85 pub struct Callee<'blk, 'tcx: 'blk> {
  86     pub bcx: Block<'blk, 'tcx>,
  87     pub data: CalleeData<'tcx>,
  88 }
  89
  90 fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, expr: &ast::Expr)
  91                      -> Callee<'blk, 'tcx> {
  92     let _icx = push_ctxt("trans_callee");
  93     debug!("callee::trans(expr={})", expr.repr(bcx.tcx()));
  94
  95     // pick out special kinds of expressions that can be called:
  96     match expr.node {
  97         ast::ExprPath(..) => {
  98             return trans_def(bcx, bcx.def(expr.id), expr);
  99         }
 100         _ => {}
 101     }
 102
 103     // any other expressions are closures:
 104     return datum_callee(bcx, expr);
 105
 106     fn datum_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, expr: &ast::Expr)
 107                                 -> Callee<'blk, 'tcx> {
 108         let DatumBlock { bcx, datum, .. } = expr::trans(bcx, expr);
 109         match datum.ty.sty {
 110             ty::ty_bare_fn(..) => {
 111                 let llval = datum.to_llscalarish(bcx);
 112                 return Callee {
 113                     bcx: bcx,
 114                     data: Fn(llval),
 115                 };
 116             }
 117             _ => {
 118                 bcx.tcx().sess.span_bug(
 119                     expr.span,
 120                     &format!("type of callee is neither bare-fn nor closure: \
 121                              {}",
 122                             bcx.ty_to_string(datum.ty)));
 123             }
 124         }
 125     }
 126
 127     fn fn_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, llfn: ValueRef)
 128                              -> Callee<'blk, 'tcx> {
 129         return Callee {
 130             bcx: bcx,
 131             data: Fn(llfn),
 132         };
 133     }
 134
 135     fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 136                              def: def::Def,
 137                              ref_expr: &ast::Expr)
 138                              -> Callee<'blk, 'tcx> {
 139         debug!("trans_def(def={}, ref_expr={})", def.repr(bcx.tcx()), ref_expr.repr(bcx.tcx()));
 140         let expr_ty = common::node_id_type(bcx, ref_expr.id);
 141         match def {
 142             def::DefFn(did, _) if {
 143                 let maybe_def_id = inline::get_local_instance(bcx.ccx(), did);
 144                 let maybe_ast_node = maybe_def_id.and_then(|def_id| bcx.tcx().map
 145                                                                              .find(def_id.node));
 146                 match maybe_ast_node {
 147                     Some(ast_map::NodeStructCtor(_)) => true,
 148                     _ => false
 149                 }
 150             } => {
 151                 let substs = common::node_id_substs(bcx.ccx(),
 152                                                     ExprId(ref_expr.id),
 153                                                     bcx.fcx.param_substs);
 154                 Callee {
 155                     bcx: bcx,
 156                     data: NamedTupleConstructor(substs, 0)
 157                 }
 158             }
 159             def::DefFn(did, _) if match expr_ty.sty {
 160                 ty::ty_bare_fn(_, ref f) => f.abi == synabi::RustIntrinsic,
 161                 _ => false
 162             } => {
 163                 let substs = common::node_id_substs(bcx.ccx(),
 164                                                     ExprId(ref_expr.id),
 165                                                     bcx.fcx.param_substs);
 166                 let def_id = inline::maybe_instantiate_inline(bcx.ccx(), did);
 167                 Callee { bcx: bcx, data: Intrinsic(def_id.node, substs) }
 168             }
 169             def::DefFn(did, _) | def::DefMethod(did, def::FromImpl(_)) => {
 170                 fn_callee(bcx, trans_fn_ref(bcx.ccx(), did, ExprId(ref_expr.id),
 171                                             bcx.fcx.param_substs).val)
 172             }
 173             def::DefMethod(meth_did, def::FromTrait(trait_did)) => {
 174                 fn_callee(bcx, meth::trans_static_method_callee(bcx.ccx(),
 175                                                                 meth_did,
 176                                                                 trait_did,
 177                                                                 ref_expr.id,
 178                                                                 bcx.fcx.param_substs).val)
 179             }
 180             def::DefVariant(tid, vid, _) => {
 181                 let vinfo = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
 182                 let substs = common::node_id_substs(bcx.ccx(),
 183                                                     ExprId(ref_expr.id),
 184                                                     bcx.fcx.param_substs);
 185
 186                 // Nullary variants are not callable
 187                 assert!(!vinfo.args.is_empty());
 188
 189                 Callee {
 190                     bcx: bcx,
 191                     data: NamedTupleConstructor(substs, vinfo.disr_val)
 192                 }
 193             }
 194             def::DefStruct(_) => {
 195                 let substs = common::node_id_substs(bcx.ccx(),
 196                                                     ExprId(ref_expr.id),
 197                                                     bcx.fcx.param_substs);
 198                 Callee {
 199                     bcx: bcx,
 200                     data: NamedTupleConstructor(substs, 0)
 201                 }
 202             }
 203             def::DefStatic(..) |
 204             def::DefConst(..) |
 205             def::DefLocal(..) |
 206             def::DefUpvar(..) => {
 207                 datum_callee(bcx, ref_expr)
 208             }
 209             def::DefMod(..) | def::DefForeignMod(..) | def::DefTrait(..) |
 210             def::DefTy(..) | def::DefPrimTy(..) | def::DefAssociatedTy(..) |
 211             def::DefUse(..) | def::DefRegion(..) | def::DefLabel(..) |
 212             def::DefTyParam(..) | def::DefSelfTy(..) => {
 213                 bcx.tcx().sess.span_bug(
 214                     ref_expr.span,
 215                     &format!("cannot translate def {:?} \
 216                              to a callable thing!", def));
 217             }
 218         }
 219     }
 220 }
 221
 222 /// Translates a reference (with id `ref_id`) to the fn/method with id `def_id` into a function
 223 /// pointer. This may require monomorphization or inlining.
 224 pub fn trans_fn_ref<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 225                               def_id: ast::DefId,
 226                               node: ExprOrMethodCall,
 227                               param_substs: &'tcx subst::Substs<'tcx>)
 228                               -> Datum<'tcx, Rvalue> {
 229     let _icx = push_ctxt("trans_fn_ref");
 230
 231     let substs = common::node_id_substs(ccx, node, param_substs);
 232     debug!("trans_fn_ref(def_id={}, node={:?}, substs={})",
 233            def_id.repr(ccx.tcx()),
 234            node,
 235            substs.repr(ccx.tcx()));
 236     trans_fn_ref_with_substs(ccx, def_id, node, param_substs, substs)
 237 }
 238
 239 fn trans_fn_ref_with_substs_to_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 240                                                   def_id: ast::DefId,
 241                                                   ref_id: ast::NodeId,
 242                                                   substs: subst::Substs<'tcx>)
 243                                                   -> Callee<'blk, 'tcx> {
 244     Callee {
 245         bcx: bcx,
 246         data: Fn(trans_fn_ref_with_substs(bcx.ccx(),
 247                                           def_id,
 248                                           ExprId(ref_id),
 249                                           bcx.fcx.param_substs,
 250                                           substs).val),
 251     }
 252 }
 253
 254 /// Translates an adapter that implements the `Fn` trait for a fn
 255 /// pointer. This is basically the equivalent of something like:
 256 ///
 257 /// ```
 258 /// impl<'a> Fn(&'a int) -> &'a int for fn(&int) -> &int {
 259 ///     extern "rust-abi" fn call(&self, args: (&'a int,)) -> &'a int {
 260 ///         (*self)(args.0)
 261 ///     }
 262 /// }
 263 /// ```
 264 ///
 265 /// but for the bare function type given.
 266 pub fn trans_fn_pointer_shim<'a, 'tcx>(
 267     ccx: &'a CrateContext<'a, 'tcx>,
 268     closure_kind: ty::ClosureKind,
 269     bare_fn_ty: Ty<'tcx>)
 270     -> ValueRef
 271 {
 272     let _icx = push_ctxt("trans_fn_pointer_shim");
 273     let tcx = ccx.tcx();
 274
 275     // Normalize the type for better caching.
 276     let bare_fn_ty = common::erase_regions(tcx, &bare_fn_ty);
 277
 278     // If this is an impl of `Fn` or `FnMut` trait, the receiver is `&self`.
 279     let is_by_ref = match closure_kind {
 280         ty::FnClosureKind | ty::FnMutClosureKind => true,
 281         ty::FnOnceClosureKind => false,
 282     };
 283     let bare_fn_ty_maybe_ref = if is_by_ref {
 284         ty::mk_imm_rptr(tcx, tcx.mk_region(ty::ReStatic), bare_fn_ty)
 285     } else {
 286         bare_fn_ty
 287     };
 288
 289     // Check if we already trans'd this shim.
 290     match ccx.fn_pointer_shims().borrow().get(&bare_fn_ty_maybe_ref) {
 291         Some(&llval) => { return llval; }
 292         None => { }
 293     }
 294
 295     debug!("trans_fn_pointer_shim(bare_fn_ty={})",
 296            bare_fn_ty.repr(tcx));
 297
 298     // Construct the "tuply" version of `bare_fn_ty`. It takes two arguments: `self`,
 299     // which is the fn pointer, and `args`, which is the arguments tuple.
 300     let (opt_def_id, sig) =
 301         match bare_fn_ty.sty {
 302             ty::ty_bare_fn(opt_def_id,
 303                            &ty::BareFnTy { unsafety: ast::Unsafety::Normal,
 304                                            abi: synabi::Rust,
 305                                            ref sig }) => {
 306                 (opt_def_id, sig)
 307             }
 308
 309             _ => {
 310                 tcx.sess.bug(&format!("trans_fn_pointer_shim invoked on invalid type: {}",
 311                                            bare_fn_ty.repr(tcx)));
 312             }
 313         };
 314     let sig = ty::erase_late_bound_regions(tcx, sig);
 315     let tuple_input_ty = ty::mk_tup(tcx, sig.inputs.to_vec());
 316     let tuple_fn_ty = ty::mk_bare_fn(tcx,
 317                                      opt_def_id,
 318                                      tcx.mk_bare_fn(ty::BareFnTy {
 319                                          unsafety: ast::Unsafety::Normal,
 320                                          abi: synabi::RustCall,
 321                                          sig: ty::Binder(ty::FnSig {
 322                                              inputs: vec![bare_fn_ty_maybe_ref,
 323                                                           tuple_input_ty],
 324                                              output: sig.output,
 325                                              variadic: false
 326                                          })}));
 327     debug!("tuple_fn_ty: {}", tuple_fn_ty.repr(tcx));
 328
 329     //
 330     let function_name = link::mangle_internal_name_by_type_and_seq(ccx, bare_fn_ty,
 331                                                                    "fn_pointer_shim");
 332     let llfn = declare::declare_internal_rust_fn(ccx, &function_name[..], tuple_fn_ty);
 333
 334     //
 335     let empty_substs = tcx.mk_substs(Substs::trans_empty());
 336     let (block_arena, fcx): (TypedArena<_>, FunctionContext);
 337     block_arena = TypedArena::new();
 338     fcx = new_fn_ctxt(ccx,
 339                       llfn,
 340                       ast::DUMMY_NODE_ID,
 341                       false,
 342                       sig.output,
 343                       empty_substs,
 344                       None,
 345                       &block_arena);
 346     let mut bcx = init_function(&fcx, false, sig.output);
 347
 348     // the first argument (`self`) will be ptr to the the fn pointer
 349     let llfnpointer = if is_by_ref {
 350         Load(bcx, get_param(fcx.llfn, fcx.arg_pos(0) as u32))
 351     } else {
 352         get_param(fcx.llfn, fcx.arg_pos(0) as u32)
 353     };
 354
 355     // the remaining arguments will be the untupled values
 356     let llargs: Vec<_> =
 357         sig.inputs.iter()
 358         .enumerate()
 359         .map(|(i, _)| get_param(fcx.llfn, fcx.arg_pos(i+1) as u32))
 360         .collect();
 361     assert!(!fcx.needs_ret_allocas);
 362
 363     let dest = fcx.llretslotptr.get().map(|_|
 364         expr::SaveIn(fcx.get_ret_slot(bcx, sig.output, "ret_slot"))
 365     );
 366
 367     bcx = trans_call_inner(bcx,
 368                            DebugLoc::None,
 369                            bare_fn_ty,
 370                            |bcx, _| Callee { bcx: bcx, data: Fn(llfnpointer) },
 371                            ArgVals(&llargs[..]),
 372                            dest).bcx;
 373
 374     finish_fn(&fcx, bcx, sig.output, DebugLoc::None);
 375
 376     ccx.fn_pointer_shims().borrow_mut().insert(bare_fn_ty_maybe_ref, llfn);
 377
 378     llfn
 379 }
 380
 381 /// Translates a reference to a fn/method item, monomorphizing and
 382 /// inlining as it goes.
 383 ///
 384 /// # Parameters
 385 ///
 386 /// - `ccx`: the crate context
 387 /// - `def_id`: def id of the fn or method item being referenced
 388 /// - `node`: node id of the reference to the fn/method, if applicable.
 389 ///   This parameter may be zero; but, if so, the resulting value may not
 390 ///   have the right type, so it must be cast before being used.
 391 /// - `param_substs`: if the `node` is in a polymorphic function, these
 392 ///   are the substitutions required to monomorphize its type
 393 /// - `substs`: values for each of the fn/method's parameters
 394 pub fn trans_fn_ref_with_substs<'a, 'tcx>(
 395     ccx: &CrateContext<'a, 'tcx>,
 396     def_id: ast::DefId,
 397     node: ExprOrMethodCall,
 398     param_substs: &'tcx subst::Substs<'tcx>,
 399     substs: subst::Substs<'tcx>)
 400     -> Datum<'tcx, Rvalue>
 401 {
 402     let _icx = push_ctxt("trans_fn_ref_with_substs");
 403     let tcx = ccx.tcx();
 404
 405     debug!("trans_fn_ref_with_substs(def_id={}, node={:?}, \
 406             param_substs={}, substs={})",
 407            def_id.repr(tcx),
 408            node,
 409            param_substs.repr(tcx),
 410            substs.repr(tcx));
 411
 412     assert!(substs.types.all(|t| !ty::type_needs_infer(*t)));
 413     assert!(substs.types.all(|t| !ty::type_has_escaping_regions(*t)));
 414     let substs = substs.erase_regions();
 415
 416     // Load the info for the appropriate trait if necessary.
 417     match ty::trait_of_item(tcx, def_id) {
 418         None => {}
 419         Some(trait_id) => {
 420             ty::populate_implementations_for_trait_if_necessary(tcx, trait_id)
 421         }
 422     }
 423
 424     // We need to do a bunch of special handling for default methods.
 425     // We need to modify the def_id and our substs in order to monomorphize
 426     // the function.
 427     let (is_default, def_id, substs) = match ty::provided_source(tcx, def_id) {
 428         None => {
 429             (false, def_id, tcx.mk_substs(substs))
 430         }
 431         Some(source_id) => {
 432             // There are two relevant substitutions when compiling
 433             // default methods. First, there is the substitution for
 434             // the type parameters of the impl we are using and the
 435             // method we are calling. This substitution is the substs
 436             // argument we already have.
 437             // In order to compile a default method, though, we need
 438             // to consider another substitution: the substitution for
 439             // the type parameters on trait; the impl we are using
 440             // implements the trait at some particular type
 441             // parameters, and we need to substitute for those first.
 442             // So, what we need to do is find this substitution and
 443             // compose it with the one we already have.
 444
 445             let impl_id = ty::impl_or_trait_item(tcx, def_id).container()
 446                                                              .id();
 447             let impl_or_trait_item = ty::impl_or_trait_item(tcx, source_id);
 448             match impl_or_trait_item {
 449                 ty::MethodTraitItem(method) => {
 450                     let trait_ref = ty::impl_trait_ref(tcx, impl_id).unwrap();
 451
 452                     // Compute the first substitution
 453                     let first_subst =
 454                         ty::make_substs_for_receiver_types(tcx, &*trait_ref, &*method)
 455                         .erase_regions();
 456
 457                     // And compose them
 458                     let new_substs = tcx.mk_substs(first_subst.subst(tcx, &substs));
 459
 460                     debug!("trans_fn_with_vtables - default method: \
 461                             substs = {}, trait_subst = {}, \
 462                             first_subst = {}, new_subst = {}",
 463                            substs.repr(tcx), trait_ref.substs.repr(tcx),
 464                            first_subst.repr(tcx), new_substs.repr(tcx));
 465
 466                     (true, source_id, new_substs)
 467                 }
 468                 ty::TypeTraitItem(_) => {
 469                     tcx.sess.bug("trans_fn_ref_with_vtables() tried \
 470                                   to translate an associated type?!")
 471                 }
 472             }
 473         }
 474     };
 475
 476     // If this is a closure, redirect to it.
 477     match closure::get_or_create_declaration_if_closure(ccx, def_id, substs) {
 478         None => {}
 479         Some(llfn) => return llfn,
 480     }
 481
 482     // Check whether this fn has an inlined copy and, if so, redirect
 483     // def_id to the local id of the inlined copy.
 484     let def_id = inline::maybe_instantiate_inline(ccx, def_id);
 485
 486     // We must monomorphise if the fn has type parameters, is a default method,
 487     // or is a named tuple constructor.
 488     let must_monomorphise = if !substs.types.is_empty() || is_default {
 489         true
 490     } else if def_id.krate == ast::LOCAL_CRATE {
 491         let map_node = session::expect(
 492             ccx.sess(),
 493             tcx.map.find(def_id.node),
 494             || "local item should be in ast map".to_string());
 495
 496         match map_node {
 497             ast_map::NodeVariant(v) => match v.node.kind {
 498                 ast::TupleVariantKind(ref args) => !args.is_empty(),
 499                 _ => false
 500             },
 501             ast_map::NodeStructCtor(_) => true,
 502             _ => false
 503         }
 504     } else {
 505         false
 506     };
 507
 508     // Create a monomorphic version of generic functions
 509     if must_monomorphise {
 510         // Should be either intra-crate or inlined.
 511         assert_eq!(def_id.krate, ast::LOCAL_CRATE);
 512
 513         let opt_ref_id = match node {
 514             ExprId(id) => if id != 0 { Some(id) } else { None },
 515             MethodCallKey(_) => None,
 516         };
 517
 518         let (val, fn_ty, must_cast) =
 519             monomorphize::monomorphic_fn(ccx, def_id, substs, opt_ref_id);
 520         if must_cast && node != ExprId(0) {
 521             // Monotype of the REFERENCE to the function (type params
 522             // are subst'd)
 523             let ref_ty = match node {
 524                 ExprId(id) => ty::node_id_to_type(tcx, id),
 525                 MethodCallKey(method_call) => {
 526                     tcx.method_map.borrow().get(&method_call).unwrap().ty
 527                 }
 528             };
 529             let ref_ty = monomorphize::apply_param_substs(tcx,
 530                                                           param_substs,
 531                                                           &ref_ty);
 532             let llptrty = type_of::type_of_fn_from_ty(ccx, ref_ty).ptr_to();
 533             if llptrty != common::val_ty(val) {
 534                 let val = consts::ptrcast(val, llptrty);
 535                 return Datum::new(val, ref_ty, Rvalue::new(ByValue));
 536             }
 537         }
 538         return Datum::new(val, fn_ty, Rvalue::new(ByValue));
 539     }
 540
 541     // Type scheme of the function item (may have type params)
 542     let fn_type_scheme = ty::lookup_item_type(tcx, def_id);
 543     let fn_type = monomorphize::normalize_associated_type(tcx, &fn_type_scheme.ty);
 544
 545     // Find the actual function pointer.
 546     let mut val = {
 547         if def_id.krate == ast::LOCAL_CRATE {
 548             // Internal reference.
 549             get_item_val(ccx, def_id.node)
 550         } else {
 551             // External reference.
 552             trans_external_path(ccx, def_id, fn_type)
 553         }
 554     };
 555
 556     // This is subtle and surprising, but sometimes we have to bitcast
 557     // the resulting fn pointer.  The reason has to do with external
 558     // functions.  If you have two crates that both bind the same C
 559     // library, they may not use precisely the same types: for
 560     // example, they will probably each declare their own structs,
 561     // which are distinct types from LLVM's point of view (nominal
 562     // types).
 563     //
 564     // Now, if those two crates are linked into an application, and
 565     // they contain inlined code, you can wind up with a situation
 566     // where both of those functions wind up being loaded into this
 567     // application simultaneously. In that case, the same function
 568     // (from LLVM's point of view) requires two types. But of course
 569     // LLVM won't allow one function to have two types.
 570     //
 571     // What we currently do, therefore, is declare the function with
 572     // one of the two types (whichever happens to come first) and then
 573     // bitcast as needed when the function is referenced to make sure
 574     // it has the type we expect.
 575     //
 576     // This can occur on either a crate-local or crate-external
 577     // reference. It also occurs when testing libcore and in some
 578     // other weird situations. Annoying.
 579     let llty = type_of::type_of_fn_from_ty(ccx, fn_type);
 580     let llptrty = llty.ptr_to();
 581     if common::val_ty(val) != llptrty {
 582         debug!("trans_fn_ref_with_vtables(): casting pointer!");
 583         val = consts::ptrcast(val, llptrty);
 584     } else {
 585         debug!("trans_fn_ref_with_vtables(): not casting pointer!");
 586     }
 587
 588     Datum::new(val, fn_type, Rvalue::new(ByValue))
 589 }
 590
 591 // ______________________________________________________________________
 592 // Translating calls
 593
 594 pub fn trans_call<'a, 'blk, 'tcx>(in_cx: Block<'blk, 'tcx>,
 595                                   call_expr: &ast::Expr,
 596                                   f: &ast::Expr,
 597                                   args: CallArgs<'a, 'tcx>,
 598                                   dest: expr::Dest)
 599                                   -> Block<'blk, 'tcx> {
 600     let _icx = push_ctxt("trans_call");
 601     trans_call_inner(in_cx,
 602                      call_expr.debug_loc(),
 603                      common::expr_ty_adjusted(in_cx, f),
 604                      |cx, _| trans(cx, f),
 605                      args,
 606                      Some(dest)).bcx
 607 }
 608
 609 pub fn trans_method_call<'a, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 610                                          call_expr: &ast::Expr,
 611                                          rcvr: &ast::Expr,
 612                                          args: CallArgs<'a, 'tcx>,
 613                                          dest: expr::Dest)
 614                                          -> Block<'blk, 'tcx> {
 615     let _icx = push_ctxt("trans_method_call");
 616     debug!("trans_method_call(call_expr={})", call_expr.repr(bcx.tcx()));
 617     let method_call = MethodCall::expr(call_expr.id);
 618     let method_ty = match bcx.tcx().method_map.borrow().get(&method_call) {
 619         Some(method) => match method.origin {
 620             ty::MethodTraitObject(_) => match method.ty.sty {
 621                 ty::ty_bare_fn(_, ref fty) => {
 622                     ty::mk_bare_fn(bcx.tcx(), None, meth::opaque_method_ty(bcx.tcx(), fty))
 623                 }
 624                 _ => method.ty
 625             },
 626             _ => method.ty
 627         },
 628         None => panic!("method not found in trans_method_call")
 629     };
 630     trans_call_inner(
 631         bcx,
 632         call_expr.debug_loc(),
 633         common::monomorphize_type(bcx, method_ty),
 634         |cx, arg_cleanup_scope| {
 635             meth::trans_method_callee(cx, method_call, Some(rcvr), arg_cleanup_scope)
 636         },
 637         args,
 638         Some(dest)).bcx
 639 }
 640
 641 pub fn trans_lang_call<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 642                                    did: ast::DefId,
 643                                    args: &[ValueRef],
 644                                    dest: Option<expr::Dest>,
 645                                    debug_loc: DebugLoc)
 646                                    -> Result<'blk, 'tcx> {
 647     let fty = if did.krate == ast::LOCAL_CRATE {
 648         ty::node_id_to_type(bcx.tcx(), did.node)
 649     } else {
 650         csearch::get_type(bcx.tcx(), did).ty
 651     };
 652     callee::trans_call_inner(bcx,
 653                              debug_loc,
 654                              fty,
 655                              |bcx, _| {
 656                                 trans_fn_ref_with_substs_to_callee(bcx,
 657                                                                    did,
 658                                                                    0,
 659                                                                    subst::Substs::trans_empty())
 660                              },
 661                              ArgVals(args),
 662                              dest)
 663 }
 664
 665 /// This behemoth of a function translates function calls. Unfortunately, in order to generate more
 666 /// efficient LLVM output at -O0, it has quite a complex signature (refactoring this into two
 667 /// functions seems like a good idea).
 668 ///
 669 /// In particular, for lang items, it is invoked with a dest of None, and in that case the return
 670 /// value contains the result of the fn. The lang item must not return a structural type or else
 671 /// all heck breaks loose.
 672 ///
 673 /// For non-lang items, `dest` is always Some, and hence the result is written into memory
 674 /// somewhere. Nonetheless we return the actual return value of the function.
 675 pub fn trans_call_inner<'a, 'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
 676                                            debug_loc: DebugLoc,
 677                                            callee_ty: Ty<'tcx>,
 678                                            get_callee: F,
 679                                            args: CallArgs<'a, 'tcx>,
 680                                            dest: Option<expr::Dest>)
 681                                            -> Result<'blk, 'tcx> where
 682     F: FnOnce(Block<'blk, 'tcx>, cleanup::ScopeId) -> Callee<'blk, 'tcx>,
 683 {
 684     // Introduce a temporary cleanup scope that will contain cleanups
 685     // for the arguments while they are being evaluated. The purpose
 686     // this cleanup is to ensure that, should a panic occur while
 687     // evaluating argument N, the values for arguments 0...N-1 are all
 688     // cleaned up. If no panic occurs, the values are handed off to
 689     // the callee, and hence none of the cleanups in this temporary
 690     // scope will ever execute.
 691     let fcx = bcx.fcx;
 692     let ccx = fcx.ccx;
 693     let arg_cleanup_scope = fcx.push_custom_cleanup_scope();
 694
 695     let callee = get_callee(bcx, cleanup::CustomScope(arg_cleanup_scope));
 696     let mut bcx = callee.bcx;
 697
 698     let (abi, ret_ty) = match callee_ty.sty {
 699         ty::ty_bare_fn(_, ref f) => {
 700             let output = ty::erase_late_bound_regions(bcx.tcx(), &f.sig.output());
 701             (f.abi, output)
 702         }
 703         _ => panic!("expected bare rust fn or closure in trans_call_inner")
 704     };
 705
 706     let (llfn, llenv, llself) = match callee.data {
 707         Fn(llfn) => {
 708             (llfn, None, None)
 709         }
 710         TraitItem(d) => {
 711             (d.llfn, None, Some(d.llself))
 712         }
 713         Intrinsic(node, substs) => {
 714             assert!(abi == synabi::RustIntrinsic);
 715             assert!(dest.is_some());
 716
 717             let call_info = match debug_loc {
 718                 DebugLoc::At(id, span) => NodeIdAndSpan { id: id, span: span },
 719                 DebugLoc::None => {
 720                     bcx.sess().bug("No call info for intrinsic call?")
 721                 }
 722             };
 723
 724             return intrinsic::trans_intrinsic_call(bcx, node, callee_ty,
 725                                                    arg_cleanup_scope, args,
 726                                                    dest.unwrap(), substs,
 727                                                    call_info);
 728         }
 729         NamedTupleConstructor(substs, disr) => {
 730             assert!(dest.is_some());
 731             fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
 732
 733             let ctor_ty = callee_ty.subst(bcx.tcx(), &substs);
 734             return base::trans_named_tuple_constructor(bcx,
 735                                                        ctor_ty,
 736                                                        disr,
 737                                                        args,
 738                                                        dest.unwrap(),
 739                                                        debug_loc);
 740         }
 741     };
 742
 743     // Intrinsics should not become actual functions.
 744     // We trans them in place in `trans_intrinsic_call`
 745     assert!(abi != synabi::RustIntrinsic);
 746
 747     let is_rust_fn = abi == synabi::Rust || abi == synabi::RustCall;
 748
 749     // Generate a location to store the result. If the user does
 750     // not care about the result, just make a stack slot.
 751     let opt_llretslot = dest.and_then(|dest| match dest {
 752         expr::SaveIn(dst) => Some(dst),
 753         expr::Ignore => {
 754             let ret_ty = match ret_ty {
 755                 ty::FnConverging(ret_ty) => ret_ty,
 756                 ty::FnDiverging => ty::mk_nil(ccx.tcx())
 757             };
 758             if !is_rust_fn ||
 759               type_of::return_uses_outptr(ccx, ret_ty) ||
 760               bcx.fcx.type_needs_drop(ret_ty) {
 761                 // Push the out-pointer if we use an out-pointer for this
 762                 // return type, otherwise push "undef".
 763                 if common::type_is_zero_size(ccx, ret_ty) {
 764                     let llty = type_of::type_of(ccx, ret_ty);
 765                     Some(common::C_undef(llty.ptr_to()))
 766                 } else {
 767                     Some(alloc_ty(bcx, ret_ty, "__llret"))
 768                 }
 769             } else {
 770                 None
 771             }
 772         }
 773     });
 774
 775     let mut llresult = unsafe {
 776         llvm::LLVMGetUndef(Type::nil(ccx).ptr_to().to_ref())
 777     };
 778
 779     // The code below invokes the function, using either the Rust
 780     // conventions (if it is a rust fn) or the native conventions
 781     // (otherwise).  The important part is that, when all is said
 782     // and done, either the return value of the function will have been
 783     // written in opt_llretslot (if it is Some) or `llresult` will be
 784     // set appropriately (otherwise).
 785     if is_rust_fn {
 786         let mut llargs = Vec::new();
 787
 788         if let (ty::FnConverging(ret_ty), Some(mut llretslot)) = (ret_ty, opt_llretslot) {
 789             if type_of::return_uses_outptr(ccx, ret_ty) {
 790                 let llformal_ret_ty = type_of::type_of(ccx, ret_ty).ptr_to();
 791                 let llret_ty = common::val_ty(llretslot);
 792                 if llformal_ret_ty != llret_ty {
 793                     // this could happen due to e.g. subtyping
 794                     debug!("casting actual return type ({}) to match formal ({})",
 795                         bcx.llty_str(llret_ty), bcx.llty_str(llformal_ret_ty));
 796                     llretslot = PointerCast(bcx, llretslot, llformal_ret_ty);
 797                 }
 798                 llargs.push(llretslot);
 799             }
 800         }
 801
 802         // Push the environment (or a trait object's self).
 803         match (llenv, llself) {
 804             (Some(llenv), None) => llargs.push(llenv),
 805             (None, Some(llself)) => llargs.push(llself),
 806             _ => {}
 807         }
 808
 809         // Push the arguments.
 810         bcx = trans_args(bcx,
 811                          args,
 812                          callee_ty,
 813                          &mut llargs,
 814                          cleanup::CustomScope(arg_cleanup_scope),
 815                          llself.is_some(),
 816                          abi);
 817
 818         fcx.scopes.borrow_mut().last_mut().unwrap().drop_non_lifetime_clean();
 819
 820         // Invoke the actual rust fn and update bcx/llresult.
 821         let (llret, b) = base::invoke(bcx,
 822                                       llfn,
 823                                       &llargs[..],
 824                                       callee_ty,
 825                                       debug_loc);
 826         bcx = b;
 827         llresult = llret;
 828
 829         // If the Rust convention for this type is return via
 830         // the return value, copy it into llretslot.
 831         match (opt_llretslot, ret_ty) {
 832             (Some(llretslot), ty::FnConverging(ret_ty)) => {
 833                 if !type_of::return_uses_outptr(bcx.ccx(), ret_ty) &&
 834                     !common::type_is_zero_size(bcx.ccx(), ret_ty)
 835                 {
 836                     store_ty(bcx, llret, llretslot, ret_ty)
 837                 }
 838             }
 839             (_, _) => {}
 840         }
 841     } else {
 842         // Lang items are the only case where dest is None, and
 843         // they are always Rust fns.
 844         assert!(dest.is_some());
 845
 846         let mut llargs = Vec::new();
 847         let arg_tys = match args {
 848             ArgExprs(a) => a.iter().map(|x| common::expr_ty(bcx, &**x)).collect(),
 849             _ => panic!("expected arg exprs.")
 850         };
 851         bcx = trans_args(bcx,
 852                          args,
 853                          callee_ty,
 854                          &mut llargs,
 855                          cleanup::CustomScope(arg_cleanup_scope),
 856                          false,
 857                          abi);
 858         fcx.scopes.borrow_mut().last_mut().unwrap().drop_non_lifetime_clean();
 859
 860         bcx = foreign::trans_native_call(bcx,
 861                                          callee_ty,
 862                                          llfn,
 863                                          opt_llretslot.unwrap(),
 864                                          &llargs[..],
 865                                          arg_tys,
 866                                          debug_loc);
 867     }
 868
 869     fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_cleanup_scope);
 870
 871     // If the caller doesn't care about the result of this fn call,
 872     // drop the temporary slot we made.
 873     match (dest, opt_llretslot, ret_ty) {
 874         (Some(expr::Ignore), Some(llretslot), ty::FnConverging(ret_ty)) => {
 875             // drop the value if it is not being saved.
 876             bcx = glue::drop_ty(bcx,
 877                                 llretslot,
 878                                 ret_ty,
 879                                 debug_loc);
 880             call_lifetime_end(bcx, llretslot);
 881         }
 882         _ => {}
 883     }
 884
 885     if ret_ty == ty::FnDiverging {
 886         Unreachable(bcx);
 887     }
 888
 889     Result::new(bcx, llresult)
 890 }
 891
 892 pub enum CallArgs<'a, 'tcx> {
 893     // Supply value of arguments as a list of expressions that must be
 894     // translated. This is used in the common case of `foo(bar, qux)`.
 895     ArgExprs(&'a [P<ast::Expr>]),
 896
 897     // Supply value of arguments as a list of LLVM value refs; frequently
 898     // used with lang items and so forth, when the argument is an internal
 899     // value.
 900     ArgVals(&'a [ValueRef]),
 901
 902     // For overloaded operators: `(lhs, Vec(rhs, rhs_id), autoref)`. `lhs`
 903     // is the left-hand-side and `rhs/rhs_id` is the datum/expr-id of
 904     // the right-hand-side arguments (if any). `autoref` indicates whether the `rhs`
 905     // arguments should be auto-referenced
 906     ArgOverloadedOp(Datum<'tcx, Expr>, Vec<(Datum<'tcx, Expr>, ast::NodeId)>, bool),
 907
 908     // Supply value of arguments as a list of expressions that must be
 909     // translated, for overloaded call operators.
 910     ArgOverloadedCall(Vec<&'a ast::Expr>),
 911 }
 912
 913 fn trans_args_under_call_abi<'blk, 'tcx>(
 914                              mut bcx: Block<'blk, 'tcx>,
 915                              arg_exprs: &[P<ast::Expr>],
 916                              fn_ty: Ty<'tcx>,
 917                              llargs: &mut Vec<ValueRef>,
 918                              arg_cleanup_scope: cleanup::ScopeId,
 919                              ignore_self: bool)
 920                              -> Block<'blk, 'tcx>
 921 {
 922     let args =
 923         ty::erase_late_bound_regions(
 924             bcx.tcx(), &ty::ty_fn_args(fn_ty));
 925
 926     // Translate the `self` argument first.
 927     if !ignore_self {
 928         let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &*arg_exprs[0]));
 929         llargs.push(unpack_result!(bcx, {
 930             trans_arg_datum(bcx,
 931                             args[0],
 932                             arg_datum,
 933                             arg_cleanup_scope,
 934                             DontAutorefArg)
 935         }))
 936     }
 937
 938     // Now untuple the rest of the arguments.
 939     let tuple_expr = &arg_exprs[1];
 940     let tuple_type = common::node_id_type(bcx, tuple_expr.id);
 941
 942     match tuple_type.sty {
 943         ty::ty_tup(ref field_types) => {
 944             let tuple_datum = unpack_datum!(bcx,
 945                                             expr::trans(bcx, &**tuple_expr));
 946             let tuple_lvalue_datum =
 947                 unpack_datum!(bcx,
 948                               tuple_datum.to_lvalue_datum(bcx,
 949                                                           "args",
 950                                                           tuple_expr.id));
 951             let repr = adt::represent_type(bcx.ccx(), tuple_type);
 952             let repr_ptr = &*repr;
 953             llargs.extend(field_types.iter().enumerate().map(|(i, field_type)| {
 954                 let arg_datum = tuple_lvalue_datum.get_element(
 955                     bcx,
 956                     field_type,
 957                     |srcval| {
 958                         adt::trans_field_ptr(bcx, repr_ptr, srcval, 0, i)
 959                     }).to_expr_datum();
 960                 unpack_result!(bcx, trans_arg_datum(
 961                     bcx,
 962                     field_type,
 963                     arg_datum,
 964                     arg_cleanup_scope,
 965                     DontAutorefArg)
 966                 )
 967             }));
 968         }
 969         _ => {
 970             bcx.sess().span_bug(tuple_expr.span,
 971                                 "argument to `.call()` wasn't a tuple?!")
 972         }
 973     };
 974
 975     bcx
 976 }
 977
 978 fn trans_overloaded_call_args<'blk, 'tcx>(
 979                               mut bcx: Block<'blk, 'tcx>,
 980                               arg_exprs: Vec<&ast::Expr>,
 981                               fn_ty: Ty<'tcx>,
 982                               llargs: &mut Vec<ValueRef>,
 983                               arg_cleanup_scope: cleanup::ScopeId,
 984                               ignore_self: bool)
 985                               -> Block<'blk, 'tcx> {
 986     // Translate the `self` argument first.
 987     let arg_tys = ty::erase_late_bound_regions(bcx.tcx(),  &ty::ty_fn_args(fn_ty));
 988     if !ignore_self {
 989         let arg_datum = unpack_datum!(bcx, expr::trans(bcx, arg_exprs[0]));
 990         llargs.push(unpack_result!(bcx, {
 991             trans_arg_datum(bcx,
 992                             arg_tys[0],
 993                             arg_datum,
 994                             arg_cleanup_scope,
 995                             DontAutorefArg)
 996         }))
 997     }
 998
 999     // Now untuple the rest of the arguments.
1000     let tuple_type = arg_tys[1];
1001     match tuple_type.sty {
1002         ty::ty_tup(ref field_types) => {
1003             for (i, &field_type) in field_types.iter().enumerate() {
1004                 let arg_datum =
1005                     unpack_datum!(bcx, expr::trans(bcx, arg_exprs[i + 1]));
1006                 llargs.push(unpack_result!(bcx, {
1007                     trans_arg_datum(bcx,
1008                                     field_type,
1009                                     arg_datum,
1010                                     arg_cleanup_scope,
1011                                     DontAutorefArg)
1012                 }))
1013             }
1014         }
1015         _ => {
1016             bcx.sess().span_bug(arg_exprs[0].span,
1017                                 "argument to `.call()` wasn't a tuple?!")
1018         }
1019     };
1020
1021     bcx
1022 }
1023
1024 pub fn trans_args<'a, 'blk, 'tcx>(cx: Block<'blk, 'tcx>,
1025                                   args: CallArgs<'a, 'tcx>,
1026                                   fn_ty: Ty<'tcx>,
1027                                   llargs: &mut Vec<ValueRef>,
1028                                   arg_cleanup_scope: cleanup::ScopeId,
1029                                   ignore_self: bool,
1030                                   abi: synabi::Abi)
1031                                   -> Block<'blk, 'tcx> {
1032     debug!("trans_args(abi={})", abi);
1033
1034     let _icx = push_ctxt("trans_args");
1035     let arg_tys = ty::erase_late_bound_regions(cx.tcx(), &ty::ty_fn_args(fn_ty));
1036     let variadic = ty::fn_is_variadic(fn_ty);
1037
1038     let mut bcx = cx;
1039
1040     // First we figure out the caller's view of the types of the arguments.
1041     // This will be needed if this is a generic call, because the callee has
1042     // to cast her view of the arguments to the caller's view.
1043     match args {
1044         ArgExprs(arg_exprs) => {
1045             if abi == synabi::RustCall {
1046                 // This is only used for direct calls to the `call`,
1047                 // `call_mut` or `call_once` functions.
1048                 return trans_args_under_call_abi(cx,
1049                                                  arg_exprs,
1050                                                  fn_ty,
1051                                                  llargs,
1052                                                  arg_cleanup_scope,
1053                                                  ignore_self)
1054             }
1055
1056             let num_formal_args = arg_tys.len();
1057             for (i, arg_expr) in arg_exprs.iter().enumerate() {
1058                 if i == 0 && ignore_self {
1059                     continue;
1060                 }
1061                 let arg_ty = if i >= num_formal_args {
1062                     assert!(variadic);
1063                     common::expr_ty_adjusted(cx, &**arg_expr)
1064                 } else {
1065                     arg_tys[i]
1066                 };
1067
1068                 let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &**arg_expr));
1069                 llargs.push(unpack_result!(bcx, {
1070                     trans_arg_datum(bcx, arg_ty, arg_datum,
1071                                     arg_cleanup_scope,
1072                                     DontAutorefArg)
1073                 }));
1074             }
1075         }
1076         ArgOverloadedCall(arg_exprs) => {
1077             return trans_overloaded_call_args(cx,
1078                                               arg_exprs,
1079                                               fn_ty,
1080                                               llargs,
1081                                               arg_cleanup_scope,
1082                                               ignore_self)
1083         }
1084         ArgOverloadedOp(lhs, rhs, autoref) => {
1085             assert!(!variadic);
1086
1087             llargs.push(unpack_result!(bcx, {
1088                 trans_arg_datum(bcx, arg_tys[0], lhs,
1089                                 arg_cleanup_scope,
1090                                 DontAutorefArg)
1091             }));
1092
1093             assert_eq!(arg_tys.len(), 1 + rhs.len());
1094             for (rhs, rhs_id) in rhs {
1095                 llargs.push(unpack_result!(bcx, {
1096                     trans_arg_datum(bcx, arg_tys[1], rhs,
1097                                     arg_cleanup_scope,
1098                                     if autoref { DoAutorefArg(rhs_id) } else { DontAutorefArg })
1099                 }));
1100             }
1101         }
1102         ArgVals(vs) => {
1103             llargs.push_all(vs);
1104         }
1105     }
1106
1107     bcx
1108 }
1109
1110 #[derive(Copy, Clone)]
1111 pub enum AutorefArg {
1112     DontAutorefArg,
1113     DoAutorefArg(ast::NodeId)
1114 }
1115
1116 pub fn trans_arg_datum<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1117                                    formal_arg_ty: Ty<'tcx>,
1118                                    arg_datum: Datum<'tcx, Expr>,
1119                                    arg_cleanup_scope: cleanup::ScopeId,
1120                                    autoref_arg: AutorefArg)
1121                                    -> Result<'blk, 'tcx> {
1122     let _icx = push_ctxt("trans_arg_datum");
1123     let mut bcx = bcx;
1124     let ccx = bcx.ccx();
1125
1126     debug!("trans_arg_datum({})",
1127            formal_arg_ty.repr(bcx.tcx()));
1128
1129     let arg_datum_ty = arg_datum.ty;
1130
1131     debug!("   arg datum: {}", arg_datum.to_string(bcx.ccx()));
1132
1133     let mut val;
1134     // FIXME(#3548) use the adjustments table
1135     match autoref_arg {
1136         DoAutorefArg(arg_id) => {
1137             // We will pass argument by reference
1138             // We want an lvalue, so that we can pass by reference and
1139             let arg_datum = unpack_datum!(
1140                 bcx, arg_datum.to_lvalue_datum(bcx, "arg", arg_id));
1141             val = arg_datum.val;
1142         }
1143         DontAutorefArg => {
1144             // Make this an rvalue, since we are going to be
1145             // passing ownership.
1146             let arg_datum = unpack_datum!(
1147                 bcx, arg_datum.to_rvalue_datum(bcx, "arg"));
1148
1149             // Now that arg_datum is owned, get it into the appropriate
1150             // mode (ref vs value).
1151             let arg_datum = unpack_datum!(
1152                 bcx, arg_datum.to_appropriate_datum(bcx));
1153
1154             // Technically, ownership of val passes to the callee.
1155             // However, we must cleanup should we panic before the
1156             // callee is actually invoked.
1157             val = arg_datum.add_clean(bcx.fcx, arg_cleanup_scope);
1158         }
1159     }
1160
1161     if formal_arg_ty != arg_datum_ty {
1162         // this could happen due to e.g. subtyping
1163         let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, formal_arg_ty);
1164         debug!("casting actual type ({}) to match formal ({})",
1165                bcx.val_to_string(val), bcx.llty_str(llformal_arg_ty));
1166         debug!("Rust types: {}; {}", ty_to_string(bcx.tcx(), arg_datum_ty),
1167                                      ty_to_string(bcx.tcx(), formal_arg_ty));
1168         val = PointerCast(bcx, val, llformal_arg_ty);
1169     }
1170
1171     debug!("--- trans_arg_datum passing {}", bcx.val_to_string(val));
1172     Result::new(bcx, val)
1173 }