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::{self, ValueRef, get_params};
  25 use metadata::csearch;
  26 use middle::def;
  27 use middle::subst;
  28 use middle::subst::{Subst, Substs};
  29 use trans::adt;
  30 use trans::base;
  31 use trans::base::*;
  32 use trans::build::*;
  33 use trans::callee;
  34 use trans::cleanup;
  35 use trans::cleanup::CleanupMethods;
  36 use trans::closure;
  37 use trans::common::{self, Block, Result, NodeIdAndSpan, ExprId, CrateContext,
  38                     ExprOrMethodCall, FunctionContext, MethodCallKey};
  39 use trans::consts;
  40 use trans::datum::*;
  41 use trans::debuginfo::{DebugLoc, ToDebugLoc};
  42 use trans::declare;
  43 use trans::expr;
  44 use trans::glue;
  45 use trans::inline;
  46 use trans::foreign;
  47 use trans::intrinsic;
  48 use trans::meth;
  49 use trans::monomorphize;
  50 use trans::type_::Type;
  51 use trans::type_of;
  52 use middle::ty::{self, Ty};
  53 use middle::ty::MethodCall;
  54 use rustc::ast_map;
  55
  56 use syntax::abi as synabi;
  57 use syntax::ast;
  58 use syntax::ptr::P;
  59
  60 #[derive(Copy, Clone)]
  61 pub struct MethodData {
  62     pub llfn: ValueRef,
  63     pub llself: ValueRef,
  64 }
  65
  66 pub enum CalleeData<'tcx> {
  67     // Constructor for enum variant/tuple-like-struct
  68     // i.e. Some, Ok
  69     NamedTupleConstructor(subst::Substs<'tcx>, ty::Disr),
  70
  71     // Represents a (possibly monomorphized) top-level fn item or method
  72     // item. Note that this is just the fn-ptr and is not a Rust closure
  73     // value (which is a pair).
  74     Fn(/* llfn */ ValueRef),
  75
  76     Intrinsic(ast::NodeId, subst::Substs<'tcx>),
  77
  78     TraitItem(MethodData)
  79 }
  80
  81 pub struct Callee<'blk, 'tcx: 'blk> {
  82     pub bcx: Block<'blk, 'tcx>,
  83     pub data: CalleeData<'tcx>,
  84 }
  85
  86 fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, expr: &ast::Expr)
  87                      -> Callee<'blk, 'tcx> {
  88     let _icx = push_ctxt("trans_callee");
  89     debug!("callee::trans(expr={:?})", expr);
  90
  91     // pick out special kinds of expressions that can be called:
  92     match expr.node {
  93         ast::ExprPath(..) => {
  94             return trans_def(bcx, bcx.def(expr.id), expr);
  95         }
  96         _ => {}
  97     }
  98
  99     // any other expressions are closures:
 100     return datum_callee(bcx, expr);
 101
 102     fn datum_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, expr: &ast::Expr)
 103                                 -> Callee<'blk, 'tcx> {
 104         let DatumBlock { bcx, datum, .. } = expr::trans(bcx, expr);
 105         match datum.ty.sty {
 106             ty::TyBareFn(..) => {
 107                 let llval = datum.to_llscalarish(bcx);
 108                 return Callee {
 109                     bcx: bcx,
 110                     data: Fn(llval),
 111                 };
 112             }
 113             _ => {
 114                 bcx.tcx().sess.span_bug(
 115                     expr.span,
 116                     &format!("type of callee is neither bare-fn nor closure: {}",
 117                              datum.ty));
 118             }
 119         }
 120     }
 121
 122     fn fn_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, llfn: ValueRef)
 123                              -> Callee<'blk, 'tcx> {
 124         return Callee {
 125             bcx: bcx,
 126             data: Fn(llfn),
 127         };
 128     }
 129
 130     fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 131                              def: def::Def,
 132                              ref_expr: &ast::Expr)
 133                              -> Callee<'blk, 'tcx> {
 134         debug!("trans_def(def={:?}, ref_expr={:?})", def, ref_expr);
 135         let expr_ty = common::node_id_type(bcx, ref_expr.id);
 136         match def {
 137             def::DefFn(did, _) if {
 138                 let maybe_def_id = inline::get_local_instance(bcx.ccx(), did);
 139                 let maybe_ast_node = maybe_def_id.and_then(|def_id| bcx.tcx().map
 140                                                                              .find(def_id.node));
 141                 match maybe_ast_node {
 142                     Some(ast_map::NodeStructCtor(_)) => true,
 143                     _ => false
 144                 }
 145             } => {
 146                 let substs = common::node_id_substs(bcx.ccx(),
 147                                                     ExprId(ref_expr.id),
 148                                                     bcx.fcx.param_substs);
 149                 Callee {
 150                     bcx: bcx,
 151                     data: NamedTupleConstructor(substs, 0)
 152                 }
 153             }
 154             def::DefFn(did, _) if match expr_ty.sty {
 155                 ty::TyBareFn(_, ref f) => f.abi == synabi::RustIntrinsic,
 156                 _ => false
 157             } => {
 158                 let substs = common::node_id_substs(bcx.ccx(),
 159                                                     ExprId(ref_expr.id),
 160                                                     bcx.fcx.param_substs);
 161                 let def_id = inline::maybe_instantiate_inline(bcx.ccx(), did);
 162                 Callee { bcx: bcx, data: Intrinsic(def_id.node, substs) }
 163             }
 164             def::DefFn(did, _) | def::DefMethod(did, def::FromImpl(_)) => {
 165                 fn_callee(bcx, trans_fn_ref(bcx.ccx(), did, ExprId(ref_expr.id),
 166                                             bcx.fcx.param_substs).val)
 167             }
 168             def::DefMethod(meth_did, def::FromTrait(trait_did)) => {
 169                 fn_callee(bcx, meth::trans_static_method_callee(bcx.ccx(),
 170                                                                 meth_did,
 171                                                                 trait_did,
 172                                                                 ref_expr.id,
 173                                                                 bcx.fcx.param_substs).val)
 174             }
 175             def::DefVariant(tid, vid, _) => {
 176                 let vinfo = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
 177                 let substs = common::node_id_substs(bcx.ccx(),
 178                                                     ExprId(ref_expr.id),
 179                                                     bcx.fcx.param_substs);
 180
 181                 // Nullary variants are not callable
 182                 assert!(!vinfo.args.is_empty());
 183
 184                 Callee {
 185                     bcx: bcx,
 186                     data: NamedTupleConstructor(substs, vinfo.disr_val)
 187                 }
 188             }
 189             def::DefStruct(_) => {
 190                 let substs = common::node_id_substs(bcx.ccx(),
 191                                                     ExprId(ref_expr.id),
 192                                                     bcx.fcx.param_substs);
 193                 Callee {
 194                     bcx: bcx,
 195                     data: NamedTupleConstructor(substs, 0)
 196                 }
 197             }
 198             def::DefStatic(..) |
 199             def::DefConst(..) |
 200             def::DefAssociatedConst(..) |
 201             def::DefLocal(..) |
 202             def::DefUpvar(..) => {
 203                 datum_callee(bcx, ref_expr)
 204             }
 205             def::DefMod(..) | def::DefForeignMod(..) | def::DefTrait(..) |
 206             def::DefTy(..) | def::DefPrimTy(..) | def::DefAssociatedTy(..) |
 207             def::DefUse(..) | def::DefRegion(..) | def::DefLabel(..) |
 208             def::DefTyParam(..) | def::DefSelfTy(..) => {
 209                 bcx.tcx().sess.span_bug(
 210                     ref_expr.span,
 211                     &format!("cannot translate def {:?} \
 212                              to a callable thing!", def));
 213             }
 214         }
 215     }
 216 }
 217
 218 /// Translates a reference (with id `ref_id`) to the fn/method with id `def_id` into a function
 219 /// pointer. This may require monomorphization or inlining.
 220 pub fn trans_fn_ref<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 221                               def_id: ast::DefId,
 222                               node: ExprOrMethodCall,
 223                               param_substs: &'tcx subst::Substs<'tcx>)
 224                               -> Datum<'tcx, Rvalue> {
 225     let _icx = push_ctxt("trans_fn_ref");
 226
 227     let substs = common::node_id_substs(ccx, node, param_substs);
 228     debug!("trans_fn_ref(def_id={:?}, node={:?}, substs={:?})",
 229            def_id,
 230            node,
 231            substs);
 232     trans_fn_ref_with_substs(ccx, def_id, node, param_substs, substs)
 233 }
 234
 235 fn trans_fn_ref_with_substs_to_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 236                                                   def_id: ast::DefId,
 237                                                   ref_id: ast::NodeId,
 238                                                   substs: subst::Substs<'tcx>)
 239                                                   -> Callee<'blk, 'tcx> {
 240     Callee {
 241         bcx: bcx,
 242         data: Fn(trans_fn_ref_with_substs(bcx.ccx(),
 243                                           def_id,
 244                                           ExprId(ref_id),
 245                                           bcx.fcx.param_substs,
 246                                           substs).val),
 247     }
 248 }
 249
 250 /// Translates an adapter that implements the `Fn` trait for a fn
 251 /// pointer. This is basically the equivalent of something like:
 252 ///
 253 /// ```
 254 /// impl<'a> Fn(&'a int) -> &'a int for fn(&int) -> &int {
 255 ///     extern "rust-abi" fn call(&self, args: (&'a int,)) -> &'a int {
 256 ///         (*self)(args.0)
 257 ///     }
 258 /// }
 259 /// ```
 260 ///
 261 /// but for the bare function type given.
 262 pub fn trans_fn_pointer_shim<'a, 'tcx>(
 263     ccx: &'a CrateContext<'a, 'tcx>,
 264     closure_kind: ty::ClosureKind,
 265     bare_fn_ty: Ty<'tcx>)
 266     -> ValueRef
 267 {
 268     let _icx = push_ctxt("trans_fn_pointer_shim");
 269     let tcx = ccx.tcx();
 270
 271     // Normalize the type for better caching.
 272     let bare_fn_ty = common::erase_regions(tcx, &bare_fn_ty);
 273
 274     // If this is an impl of `Fn` or `FnMut` trait, the receiver is `&self`.
 275     let is_by_ref = match closure_kind {
 276         ty::FnClosureKind | ty::FnMutClosureKind => true,
 277         ty::FnOnceClosureKind => false,
 278     };
 279     let bare_fn_ty_maybe_ref = if is_by_ref {
 280         ty::mk_imm_rptr(tcx, tcx.mk_region(ty::ReStatic), bare_fn_ty)
 281     } else {
 282         bare_fn_ty
 283     };
 284
 285     // Check if we already trans'd this shim.
 286     match ccx.fn_pointer_shims().borrow().get(&bare_fn_ty_maybe_ref) {
 287         Some(&llval) => { return llval; }
 288         None => { }
 289     }
 290
 291     debug!("trans_fn_pointer_shim(bare_fn_ty={:?})",
 292            bare_fn_ty);
 293
 294     // Construct the "tuply" version of `bare_fn_ty`. It takes two arguments: `self`,
 295     // which is the fn pointer, and `args`, which is the arguments tuple.
 296     let (opt_def_id, sig) =
 297         match bare_fn_ty.sty {
 298             ty::TyBareFn(opt_def_id,
 299                            &ty::BareFnTy { unsafety: ast::Unsafety::Normal,
 300                                            abi: synabi::Rust,
 301                                            ref sig }) => {
 302                 (opt_def_id, sig)
 303             }
 304
 305             _ => {
 306                 tcx.sess.bug(&format!("trans_fn_pointer_shim invoked on invalid type: {}",
 307                                       bare_fn_ty));
 308             }
 309         };
 310     let sig = ty::erase_late_bound_regions(tcx, sig);
 311     let tuple_input_ty = ty::mk_tup(tcx, sig.inputs.to_vec());
 312     let tuple_fn_ty = ty::mk_bare_fn(tcx,
 313                                      opt_def_id,
 314                                      tcx.mk_bare_fn(ty::BareFnTy {
 315                                          unsafety: ast::Unsafety::Normal,
 316                                          abi: synabi::RustCall,
 317                                          sig: ty::Binder(ty::FnSig {
 318                                              inputs: vec![bare_fn_ty_maybe_ref,
 319                                                           tuple_input_ty],
 320                                              output: sig.output,
 321                                              variadic: false
 322                                          })}));
 323     debug!("tuple_fn_ty: {:?}", tuple_fn_ty);
 324
 325     //
 326     let function_name = link::mangle_internal_name_by_type_and_seq(ccx, bare_fn_ty,
 327                                                                    "fn_pointer_shim");
 328     let llfn = declare::declare_internal_rust_fn(ccx, &function_name[..], tuple_fn_ty);
 329
 330     //
 331     let empty_substs = tcx.mk_substs(Substs::trans_empty());
 332     let (block_arena, fcx): (TypedArena<_>, FunctionContext);
 333     block_arena = TypedArena::new();
 334     fcx = new_fn_ctxt(ccx,
 335                       llfn,
 336                       ast::DUMMY_NODE_ID,
 337                       false,
 338                       sig.output,
 339                       empty_substs,
 340                       None,
 341                       &block_arena);
 342     let mut bcx = init_function(&fcx, false, sig.output);
 343
 344     let llargs = get_params(fcx.llfn);
 345
 346     let self_idx = fcx.arg_offset();
 347     // the first argument (`self`) will be ptr to the the fn pointer
 348     let llfnpointer = if is_by_ref {
 349         Load(bcx, llargs[self_idx])
 350     } else {
 351         llargs[self_idx]
 352     };
 353
 354     assert!(!fcx.needs_ret_allocas);
 355
 356     let dest = fcx.llretslotptr.get().map(|_|
 357         expr::SaveIn(fcx.get_ret_slot(bcx, sig.output, "ret_slot"))
 358     );
 359
 360     bcx = trans_call_inner(bcx,
 361                            DebugLoc::None,
 362                            bare_fn_ty,
 363                            |bcx, _| Callee { bcx: bcx, data: Fn(llfnpointer) },
 364                            ArgVals(&llargs[(self_idx + 1)..]),
 365                            dest).bcx;
 366
 367     finish_fn(&fcx, bcx, sig.output, DebugLoc::None);
 368
 369     ccx.fn_pointer_shims().borrow_mut().insert(bare_fn_ty_maybe_ref, llfn);
 370
 371     llfn
 372 }
 373
 374 /// Translates a reference to a fn/method item, monomorphizing and
 375 /// inlining as it goes.
 376 ///
 377 /// # Parameters
 378 ///
 379 /// - `ccx`: the crate context
 380 /// - `def_id`: def id of the fn or method item being referenced
 381 /// - `node`: node id of the reference to the fn/method, if applicable.
 382 ///   This parameter may be zero; but, if so, the resulting value may not
 383 ///   have the right type, so it must be cast before being used.
 384 /// - `param_substs`: if the `node` is in a polymorphic function, these
 385 ///   are the substitutions required to monomorphize its type
 386 /// - `substs`: values for each of the fn/method's parameters
 387 pub fn trans_fn_ref_with_substs<'a, 'tcx>(
 388     ccx: &CrateContext<'a, 'tcx>,
 389     def_id: ast::DefId,
 390     node: ExprOrMethodCall,
 391     param_substs: &'tcx subst::Substs<'tcx>,
 392     substs: subst::Substs<'tcx>)
 393     -> Datum<'tcx, Rvalue>
 394 {
 395     let _icx = push_ctxt("trans_fn_ref_with_substs");
 396     let tcx = ccx.tcx();
 397
 398     debug!("trans_fn_ref_with_substs(def_id={:?}, node={:?}, \
 399             param_substs={:?}, substs={:?})",
 400            def_id,
 401            node,
 402            param_substs,
 403            substs);
 404
 405     assert!(substs.types.all(|t| !ty::type_needs_infer(*t)));
 406     assert!(substs.types.all(|t| !ty::type_has_escaping_regions(*t)));
 407     let substs = substs.erase_regions();
 408
 409     // Load the info for the appropriate trait if necessary.
 410     match ty::trait_of_item(tcx, def_id) {
 411         None => {}
 412         Some(trait_id) => {
 413             ty::populate_implementations_for_trait_if_necessary(tcx, trait_id)
 414         }
 415     }
 416
 417     // We need to do a bunch of special handling for default methods.
 418     // We need to modify the def_id and our substs in order to monomorphize
 419     // the function.
 420     let (is_default, def_id, substs) = match ty::provided_source(tcx, def_id) {
 421         None => {
 422             (false, def_id, tcx.mk_substs(substs))
 423         }
 424         Some(source_id) => {
 425             // There are two relevant substitutions when compiling
 426             // default methods. First, there is the substitution for
 427             // the type parameters of the impl we are using and the
 428             // method we are calling. This substitution is the substs
 429             // argument we already have.
 430             // In order to compile a default method, though, we need
 431             // to consider another substitution: the substitution for
 432             // the type parameters on trait; the impl we are using
 433             // implements the trait at some particular type
 434             // parameters, and we need to substitute for those first.
 435             // So, what we need to do is find this substitution and
 436             // compose it with the one we already have.
 437
 438             let impl_id = ty::impl_or_trait_item(tcx, def_id).container()
 439                                                              .id();
 440             let impl_or_trait_item = ty::impl_or_trait_item(tcx, source_id);
 441             match impl_or_trait_item {
 442                 ty::MethodTraitItem(method) => {
 443                     let trait_ref = ty::impl_trait_ref(tcx, impl_id).unwrap();
 444
 445                     // Compute the first substitution
 446                     let first_subst =
 447                         ty::make_substs_for_receiver_types(tcx, &trait_ref, &*method)
 448                         .erase_regions();
 449
 450                     // And compose them
 451                     let new_substs = tcx.mk_substs(first_subst.subst(tcx, &substs));
 452
 453                     debug!("trans_fn_with_vtables - default method: \
 454                             substs = {:?}, trait_subst = {:?}, \
 455                             first_subst = {:?}, new_subst = {:?}",
 456                            substs, trait_ref.substs,
 457                            first_subst, new_substs);
 458
 459                     (true, source_id, new_substs)
 460                 }
 461                 _ => {
 462                     tcx.sess.bug("trans_fn_ref_with_vtables() tried \
 463                                   to translate a non-method?!")
 464                 }
 465             }
 466         }
 467     };
 468
 469     // If this is a closure, redirect to it.
 470     match closure::get_or_create_declaration_if_closure(ccx, def_id, substs) {
 471         None => {}
 472         Some(llfn) => return llfn,
 473     }
 474
 475     // Check whether this fn has an inlined copy and, if so, redirect
 476     // def_id to the local id of the inlined copy.
 477     let def_id = inline::maybe_instantiate_inline(ccx, def_id);
 478
 479     // We must monomorphise if the fn has type parameters, is a default method,
 480     // or is a named tuple constructor.
 481     let must_monomorphise = if !substs.types.is_empty() || is_default {
 482         true
 483     } else if def_id.krate == ast::LOCAL_CRATE {
 484         let map_node = session::expect(
 485             ccx.sess(),
 486             tcx.map.find(def_id.node),
 487             || "local item should be in ast map".to_string());
 488
 489         match map_node {
 490             ast_map::NodeVariant(v) => match v.node.kind {
 491                 ast::TupleVariantKind(ref args) => !args.is_empty(),
 492                 _ => false
 493             },
 494             ast_map::NodeStructCtor(_) => true,
 495             _ => false
 496         }
 497     } else {
 498         false
 499     };
 500
 501     debug!("trans_fn_ref_with_substs({:?}) must_monomorphise: {}",
 502            def_id, must_monomorphise);
 503
 504     // Create a monomorphic version of generic functions
 505     if must_monomorphise {
 506         // Should be either intra-crate or inlined.
 507         assert_eq!(def_id.krate, ast::LOCAL_CRATE);
 508
 509         let opt_ref_id = match node {
 510             ExprId(id) => if id != 0 { Some(id) } else { None },
 511             MethodCallKey(_) => None,
 512         };
 513
 514         let (val, fn_ty, must_cast) =
 515             monomorphize::monomorphic_fn(ccx, def_id, substs, opt_ref_id);
 516         if must_cast && node != ExprId(0) {
 517             // Monotype of the REFERENCE to the function (type params
 518             // are subst'd)
 519             let ref_ty = match node {
 520                 ExprId(id) => ty::node_id_to_type(tcx, id),
 521                 MethodCallKey(method_call) => {
 522                     tcx.method_map.borrow().get(&method_call).unwrap().ty
 523                 }
 524             };
 525             let ref_ty = monomorphize::apply_param_substs(tcx,
 526                                                           param_substs,
 527                                                           &ref_ty);
 528             let llptrty = type_of::type_of_fn_from_ty(ccx, ref_ty).ptr_to();
 529             if llptrty != common::val_ty(val) {
 530                 let val = consts::ptrcast(val, llptrty);
 531                 return Datum::new(val, ref_ty, Rvalue::new(ByValue));
 532             }
 533         }
 534         return Datum::new(val, fn_ty, Rvalue::new(ByValue));
 535     }
 536
 537     // Type scheme of the function item (may have type params)
 538     let fn_type_scheme = ty::lookup_item_type(tcx, def_id);
 539     let fn_type = monomorphize::normalize_associated_type(tcx, &fn_type_scheme.ty);
 540
 541     // Find the actual function pointer.
 542     let mut val = {
 543         if def_id.krate == ast::LOCAL_CRATE {
 544             // Internal reference.
 545             get_item_val(ccx, def_id.node)
 546         } else {
 547             // External reference.
 548             trans_external_path(ccx, def_id, fn_type)
 549         }
 550     };
 551
 552     // This is subtle and surprising, but sometimes we have to bitcast
 553     // the resulting fn pointer.  The reason has to do with external
 554     // functions.  If you have two crates that both bind the same C
 555     // library, they may not use precisely the same types: for
 556     // example, they will probably each declare their own structs,
 557     // which are distinct types from LLVM's point of view (nominal
 558     // types).
 559     //
 560     // Now, if those two crates are linked into an application, and
 561     // they contain inlined code, you can wind up with a situation
 562     // where both of those functions wind up being loaded into this
 563     // application simultaneously. In that case, the same function
 564     // (from LLVM's point of view) requires two types. But of course
 565     // LLVM won't allow one function to have two types.
 566     //
 567     // What we currently do, therefore, is declare the function with
 568     // one of the two types (whichever happens to come first) and then
 569     // bitcast as needed when the function is referenced to make sure
 570     // it has the type we expect.
 571     //
 572     // This can occur on either a crate-local or crate-external
 573     // reference. It also occurs when testing libcore and in some
 574     // other weird situations. Annoying.
 575     let llty = type_of::type_of_fn_from_ty(ccx, fn_type);
 576     let llptrty = llty.ptr_to();
 577     if common::val_ty(val) != llptrty {
 578         debug!("trans_fn_ref_with_vtables(): casting pointer!");
 579         val = consts::ptrcast(val, llptrty);
 580     } else {
 581         debug!("trans_fn_ref_with_vtables(): not casting pointer!");
 582     }
 583
 584     Datum::new(val, fn_type, Rvalue::new(ByValue))
 585 }
 586
 587 // ______________________________________________________________________
 588 // Translating calls
 589
 590 pub fn trans_call<'a, 'blk, 'tcx>(in_cx: Block<'blk, 'tcx>,
 591                                   call_expr: &ast::Expr,
 592                                   f: &ast::Expr,
 593                                   args: CallArgs<'a, 'tcx>,
 594                                   dest: expr::Dest)
 595                                   -> Block<'blk, 'tcx> {
 596     let _icx = push_ctxt("trans_call");
 597     trans_call_inner(in_cx,
 598                      call_expr.debug_loc(),
 599                      common::expr_ty_adjusted(in_cx, f),
 600                      |cx, _| trans(cx, f),
 601                      args,
 602                      Some(dest)).bcx
 603 }
 604
 605 pub fn trans_method_call<'a, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 606                                          call_expr: &ast::Expr,
 607                                          rcvr: &ast::Expr,
 608                                          args: CallArgs<'a, 'tcx>,
 609                                          dest: expr::Dest)
 610                                          -> Block<'blk, 'tcx> {
 611     let _icx = push_ctxt("trans_method_call");
 612     debug!("trans_method_call(call_expr={:?})", call_expr);
 613     let method_call = MethodCall::expr(call_expr.id);
 614     let method_ty = match bcx.tcx().method_map.borrow().get(&method_call) {
 615         Some(method) => match method.origin {
 616             ty::MethodTraitObject(_) => match method.ty.sty {
 617                 ty::TyBareFn(_, ref fty) => {
 618                     ty::mk_bare_fn(bcx.tcx(), None, meth::opaque_method_ty(bcx.tcx(), fty))
 619                 }
 620                 _ => method.ty
 621             },
 622             _ => method.ty
 623         },
 624         None => panic!("method not found in trans_method_call")
 625     };
 626     trans_call_inner(
 627         bcx,
 628         call_expr.debug_loc(),
 629         common::monomorphize_type(bcx, method_ty),
 630         |cx, arg_cleanup_scope| {
 631             meth::trans_method_callee(cx, method_call, Some(rcvr), arg_cleanup_scope)
 632         },
 633         args,
 634         Some(dest)).bcx
 635 }
 636
 637 pub fn trans_lang_call<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 638                                    did: ast::DefId,
 639                                    args: &[ValueRef],
 640                                    dest: Option<expr::Dest>,
 641                                    debug_loc: DebugLoc)
 642                                    -> Result<'blk, 'tcx> {
 643     let fty = if did.krate == ast::LOCAL_CRATE {
 644         ty::node_id_to_type(bcx.tcx(), did.node)
 645     } else {
 646         csearch::get_type(bcx.tcx(), did).ty
 647     };
 648     callee::trans_call_inner(bcx,
 649                              debug_loc,
 650                              fty,
 651                              |bcx, _| {
 652                                 trans_fn_ref_with_substs_to_callee(bcx,
 653                                                                    did,
 654                                                                    0,
 655                                                                    subst::Substs::trans_empty())
 656                              },
 657                              ArgVals(args),
 658                              dest)
 659 }
 660
 661 /// This behemoth of a function translates function calls. Unfortunately, in order to generate more
 662 /// efficient LLVM output at -O0, it has quite a complex signature (refactoring this into two
 663 /// functions seems like a good idea).
 664 ///
 665 /// In particular, for lang items, it is invoked with a dest of None, and in that case the return
 666 /// value contains the result of the fn. The lang item must not return a structural type or else
 667 /// all heck breaks loose.
 668 ///
 669 /// For non-lang items, `dest` is always Some, and hence the result is written into memory
 670 /// somewhere. Nonetheless we return the actual return value of the function.
 671 pub fn trans_call_inner<'a, 'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
 672                                            debug_loc: DebugLoc,
 673                                            callee_ty: Ty<'tcx>,
 674                                            get_callee: F,
 675                                            args: CallArgs<'a, 'tcx>,
 676                                            dest: Option<expr::Dest>)
 677                                            -> Result<'blk, 'tcx> where
 678     F: FnOnce(Block<'blk, 'tcx>, cleanup::ScopeId) -> Callee<'blk, 'tcx>,
 679 {
 680     // Introduce a temporary cleanup scope that will contain cleanups
 681     // for the arguments while they are being evaluated. The purpose
 682     // this cleanup is to ensure that, should a panic occur while
 683     // evaluating argument N, the values for arguments 0...N-1 are all
 684     // cleaned up. If no panic occurs, the values are handed off to
 685     // the callee, and hence none of the cleanups in this temporary
 686     // scope will ever execute.
 687     let fcx = bcx.fcx;
 688     let ccx = fcx.ccx;
 689     let arg_cleanup_scope = fcx.push_custom_cleanup_scope();
 690
 691     let callee = get_callee(bcx, cleanup::CustomScope(arg_cleanup_scope));
 692     let mut bcx = callee.bcx;
 693
 694     let (abi, ret_ty) = match callee_ty.sty {
 695         ty::TyBareFn(_, ref f) => {
 696             let output = ty::erase_late_bound_regions(bcx.tcx(), &f.sig.output());
 697             (f.abi, output)
 698         }
 699         _ => panic!("expected bare rust fn or closure in trans_call_inner")
 700     };
 701
 702     let (llfn, llenv, llself) = match callee.data {
 703         Fn(llfn) => {
 704             (llfn, None, None)
 705         }
 706         TraitItem(d) => {
 707             (d.llfn, None, Some(d.llself))
 708         }
 709         Intrinsic(node, substs) => {
 710             assert!(abi == synabi::RustIntrinsic);
 711             assert!(dest.is_some());
 712
 713             let call_info = match debug_loc {
 714                 DebugLoc::At(id, span) => NodeIdAndSpan { id: id, span: span },
 715                 DebugLoc::None => {
 716                     bcx.sess().bug("No call info for intrinsic call?")
 717                 }
 718             };
 719
 720             return intrinsic::trans_intrinsic_call(bcx, node, callee_ty,
 721                                                    arg_cleanup_scope, args,
 722                                                    dest.unwrap(), substs,
 723                                                    call_info);
 724         }
 725         NamedTupleConstructor(substs, disr) => {
 726             assert!(dest.is_some());
 727             fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
 728
 729             let ctor_ty = callee_ty.subst(bcx.tcx(), &substs);
 730             return base::trans_named_tuple_constructor(bcx,
 731                                                        ctor_ty,
 732                                                        disr,
 733                                                        args,
 734                                                        dest.unwrap(),
 735                                                        debug_loc);
 736         }
 737     };
 738
 739     // Intrinsics should not become actual functions.
 740     // We trans them in place in `trans_intrinsic_call`
 741     assert!(abi != synabi::RustIntrinsic);
 742
 743     let is_rust_fn = abi == synabi::Rust || abi == synabi::RustCall;
 744
 745     // Generate a location to store the result. If the user does
 746     // not care about the result, just make a stack slot.
 747     let opt_llretslot = dest.and_then(|dest| match dest {
 748         expr::SaveIn(dst) => Some(dst),
 749         expr::Ignore => {
 750             let ret_ty = match ret_ty {
 751                 ty::FnConverging(ret_ty) => ret_ty,
 752                 ty::FnDiverging => ty::mk_nil(ccx.tcx())
 753             };
 754             if !is_rust_fn ||
 755               type_of::return_uses_outptr(ccx, ret_ty) ||
 756               bcx.fcx.type_needs_drop(ret_ty) {
 757                 // Push the out-pointer if we use an out-pointer for this
 758                 // return type, otherwise push "undef".
 759                 if common::type_is_zero_size(ccx, ret_ty) {
 760                     let llty = type_of::type_of(ccx, ret_ty);
 761                     Some(common::C_undef(llty.ptr_to()))
 762                 } else {
 763                     Some(alloc_ty(bcx, ret_ty, "__llret"))
 764                 }
 765             } else {
 766                 None
 767             }
 768         }
 769     });
 770
 771     let mut llresult = unsafe {
 772         llvm::LLVMGetUndef(Type::nil(ccx).ptr_to().to_ref())
 773     };
 774
 775     // The code below invokes the function, using either the Rust
 776     // conventions (if it is a rust fn) or the native conventions
 777     // (otherwise).  The important part is that, when all is said
 778     // and done, either the return value of the function will have been
 779     // written in opt_llretslot (if it is Some) or `llresult` will be
 780     // set appropriately (otherwise).
 781     if is_rust_fn {
 782         let mut llargs = Vec::new();
 783
 784         if let (ty::FnConverging(ret_ty), Some(mut llretslot)) = (ret_ty, opt_llretslot) {
 785             if type_of::return_uses_outptr(ccx, ret_ty) {
 786                 let llformal_ret_ty = type_of::type_of(ccx, ret_ty).ptr_to();
 787                 let llret_ty = common::val_ty(llretslot);
 788                 if llformal_ret_ty != llret_ty {
 789                     // this could happen due to e.g. subtyping
 790                     debug!("casting actual return type ({}) to match formal ({})",
 791                         bcx.llty_str(llret_ty), bcx.llty_str(llformal_ret_ty));
 792                     llretslot = PointerCast(bcx, llretslot, llformal_ret_ty);
 793                 }
 794                 llargs.push(llretslot);
 795             }
 796         }
 797
 798         // Push the environment (or a trait object's self).
 799         match (llenv, llself) {
 800             (Some(llenv), None) => llargs.push(llenv),
 801             (None, Some(llself)) => llargs.push(llself),
 802             _ => {}
 803         }
 804
 805         // Push the arguments.
 806         bcx = trans_args(bcx,
 807                          args,
 808                          callee_ty,
 809                          &mut llargs,
 810                          cleanup::CustomScope(arg_cleanup_scope),
 811                          llself.is_some(),
 812                          abi);
 813
 814         fcx.scopes.borrow_mut().last_mut().unwrap().drop_non_lifetime_clean();
 815
 816         // Invoke the actual rust fn and update bcx/llresult.
 817         let (llret, b) = base::invoke(bcx,
 818                                       llfn,
 819                                       &llargs[..],
 820                                       callee_ty,
 821                                       debug_loc);
 822         bcx = b;
 823         llresult = llret;
 824
 825         // If the Rust convention for this type is return via
 826         // the return value, copy it into llretslot.
 827         match (opt_llretslot, ret_ty) {
 828             (Some(llretslot), ty::FnConverging(ret_ty)) => {
 829                 if !type_of::return_uses_outptr(bcx.ccx(), ret_ty) &&
 830                     !common::type_is_zero_size(bcx.ccx(), ret_ty)
 831                 {
 832                     store_ty(bcx, llret, llretslot, ret_ty)
 833                 }
 834             }
 835             (_, _) => {}
 836         }
 837     } else {
 838         // Lang items are the only case where dest is None, and
 839         // they are always Rust fns.
 840         assert!(dest.is_some());
 841
 842         let mut llargs = Vec::new();
 843         let arg_tys = match args {
 844             ArgExprs(a) => a.iter().map(|x| common::expr_ty_adjusted(bcx, &**x)).collect(),
 845             _ => panic!("expected arg exprs.")
 846         };
 847         bcx = trans_args(bcx,
 848                          args,
 849                          callee_ty,
 850                          &mut llargs,
 851                          cleanup::CustomScope(arg_cleanup_scope),
 852                          false,
 853                          abi);
 854         fcx.scopes.borrow_mut().last_mut().unwrap().drop_non_lifetime_clean();
 855
 856         bcx = foreign::trans_native_call(bcx,
 857                                          callee_ty,
 858                                          llfn,
 859                                          opt_llretslot.unwrap(),
 860                                          &llargs[..],
 861                                          arg_tys,
 862                                          debug_loc);
 863     }
 864
 865     fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_cleanup_scope);
 866
 867     // If the caller doesn't care about the result of this fn call,
 868     // drop the temporary slot we made.
 869     match (dest, opt_llretslot, ret_ty) {
 870         (Some(expr::Ignore), Some(llretslot), ty::FnConverging(ret_ty)) => {
 871             // drop the value if it is not being saved.
 872             bcx = glue::drop_ty(bcx,
 873                                 llretslot,
 874                                 ret_ty,
 875                                 debug_loc);
 876             call_lifetime_end(bcx, llretslot);
 877         }
 878         _ => {}
 879     }
 880
 881     if ret_ty == ty::FnDiverging {
 882         Unreachable(bcx);
 883     }
 884
 885     Result::new(bcx, llresult)
 886 }
 887
 888 pub enum CallArgs<'a, 'tcx> {
 889     // Supply value of arguments as a list of expressions that must be
 890     // translated. This is used in the common case of `foo(bar, qux)`.
 891     ArgExprs(&'a [P<ast::Expr>]),
 892
 893     // Supply value of arguments as a list of LLVM value refs; frequently
 894     // used with lang items and so forth, when the argument is an internal
 895     // value.
 896     ArgVals(&'a [ValueRef]),
 897
 898     // For overloaded operators: `(lhs, Vec(rhs, rhs_id), autoref)`. `lhs`
 899     // is the left-hand-side and `rhs/rhs_id` is the datum/expr-id of
 900     // the right-hand-side arguments (if any). `autoref` indicates whether the `rhs`
 901     // arguments should be auto-referenced
 902     ArgOverloadedOp(Datum<'tcx, Expr>, Vec<(Datum<'tcx, Expr>, ast::NodeId)>, bool),
 903
 904     // Supply value of arguments as a list of expressions that must be
 905     // translated, for overloaded call operators.
 906     ArgOverloadedCall(Vec<&'a ast::Expr>),
 907 }
 908
 909 fn trans_args_under_call_abi<'blk, 'tcx>(
 910                              mut bcx: Block<'blk, 'tcx>,
 911                              arg_exprs: &[P<ast::Expr>],
 912                              fn_ty: Ty<'tcx>,
 913                              llargs: &mut Vec<ValueRef>,
 914                              arg_cleanup_scope: cleanup::ScopeId,
 915                              ignore_self: bool)
 916                              -> Block<'blk, 'tcx>
 917 {
 918     let args =
 919         ty::erase_late_bound_regions(
 920             bcx.tcx(), &ty::ty_fn_args(fn_ty));
 921
 922     // Translate the `self` argument first.
 923     if !ignore_self {
 924         let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &*arg_exprs[0]));
 925         bcx = trans_arg_datum(bcx,
 926                               args[0],
 927                               arg_datum,
 928                               arg_cleanup_scope,
 929                               DontAutorefArg,
 930                               llargs);
 931     }
 932
 933     // Now untuple the rest of the arguments.
 934     let tuple_expr = &arg_exprs[1];
 935     let tuple_type = common::node_id_type(bcx, tuple_expr.id);
 936
 937     match tuple_type.sty {
 938         ty::TyTuple(ref field_types) => {
 939             let tuple_datum = unpack_datum!(bcx,
 940                                             expr::trans(bcx, &**tuple_expr));
 941             let tuple_lvalue_datum =
 942                 unpack_datum!(bcx,
 943                               tuple_datum.to_lvalue_datum(bcx,
 944                                                           "args",
 945                                                           tuple_expr.id));
 946             let repr = adt::represent_type(bcx.ccx(), tuple_type);
 947             let repr_ptr = &*repr;
 948             for (i, field_type) in field_types.iter().enumerate() {
 949                 let arg_datum = tuple_lvalue_datum.get_element(
 950                     bcx,
 951                     field_type,
 952                     |srcval| {
 953                         adt::trans_field_ptr(bcx, repr_ptr, srcval, 0, i)
 954                     }).to_expr_datum();
 955                 bcx = trans_arg_datum(bcx,
 956                                       field_type,
 957                                       arg_datum,
 958                                       arg_cleanup_scope,
 959                                       DontAutorefArg,
 960                                       llargs);
 961             }
 962         }
 963         _ => {
 964             bcx.sess().span_bug(tuple_expr.span,
 965                                 "argument to `.call()` wasn't a tuple?!")
 966         }
 967     };
 968
 969     bcx
 970 }
 971
 972 fn trans_overloaded_call_args<'blk, 'tcx>(
 973                               mut bcx: Block<'blk, 'tcx>,
 974                               arg_exprs: Vec<&ast::Expr>,
 975                               fn_ty: Ty<'tcx>,
 976                               llargs: &mut Vec<ValueRef>,
 977                               arg_cleanup_scope: cleanup::ScopeId,
 978                               ignore_self: bool)
 979                               -> Block<'blk, 'tcx> {
 980     // Translate the `self` argument first.
 981     let arg_tys = ty::erase_late_bound_regions(bcx.tcx(),  &ty::ty_fn_args(fn_ty));
 982     if !ignore_self {
 983         let arg_datum = unpack_datum!(bcx, expr::trans(bcx, arg_exprs[0]));
 984         bcx = trans_arg_datum(bcx,
 985                               arg_tys[0],
 986                               arg_datum,
 987                               arg_cleanup_scope,
 988                               DontAutorefArg,
 989                               llargs);
 990     }
 991
 992     // Now untuple the rest of the arguments.
 993     let tuple_type = arg_tys[1];
 994     match tuple_type.sty {
 995         ty::TyTuple(ref field_types) => {
 996             for (i, &field_type) in field_types.iter().enumerate() {
 997                 let arg_datum =
 998                     unpack_datum!(bcx, expr::trans(bcx, arg_exprs[i + 1]));
 999                 bcx = trans_arg_datum(bcx,
1000                                       field_type,
1001                                       arg_datum,
1002                                       arg_cleanup_scope,
1003                                       DontAutorefArg,
1004                                       llargs);
1005             }
1006         }
1007         _ => {
1008             bcx.sess().span_bug(arg_exprs[0].span,
1009                                 "argument to `.call()` wasn't a tuple?!")
1010         }
1011     };
1012
1013     bcx
1014 }
1015
1016 pub fn trans_args<'a, 'blk, 'tcx>(cx: Block<'blk, 'tcx>,
1017                                   args: CallArgs<'a, 'tcx>,
1018                                   fn_ty: Ty<'tcx>,
1019                                   llargs: &mut Vec<ValueRef>,
1020                                   arg_cleanup_scope: cleanup::ScopeId,
1021                                   ignore_self: bool,
1022                                   abi: synabi::Abi)
1023                                   -> Block<'blk, 'tcx> {
1024     debug!("trans_args(abi={})", abi);
1025
1026     let _icx = push_ctxt("trans_args");
1027     let arg_tys = ty::erase_late_bound_regions(cx.tcx(), &ty::ty_fn_args(fn_ty));
1028     let variadic = ty::fn_is_variadic(fn_ty);
1029
1030     let mut bcx = cx;
1031
1032     // First we figure out the caller's view of the types of the arguments.
1033     // This will be needed if this is a generic call, because the callee has
1034     // to cast her view of the arguments to the caller's view.
1035     match args {
1036         ArgExprs(arg_exprs) => {
1037             if abi == synabi::RustCall {
1038                 // This is only used for direct calls to the `call`,
1039                 // `call_mut` or `call_once` functions.
1040                 return trans_args_under_call_abi(cx,
1041                                                  arg_exprs,
1042                                                  fn_ty,
1043                                                  llargs,
1044                                                  arg_cleanup_scope,
1045                                                  ignore_self)
1046             }
1047
1048             let num_formal_args = arg_tys.len();
1049             for (i, arg_expr) in arg_exprs.iter().enumerate() {
1050                 if i == 0 && ignore_self {
1051                     continue;
1052                 }
1053                 let arg_ty = if i >= num_formal_args {
1054                     assert!(variadic);
1055                     common::expr_ty_adjusted(cx, &**arg_expr)
1056                 } else {
1057                     arg_tys[i]
1058                 };
1059
1060                 let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &**arg_expr));
1061                 bcx = trans_arg_datum(bcx, arg_ty, arg_datum,
1062                                       arg_cleanup_scope,
1063                                       DontAutorefArg,
1064                                       llargs);
1065             }
1066         }
1067         ArgOverloadedCall(arg_exprs) => {
1068             return trans_overloaded_call_args(cx,
1069                                               arg_exprs,
1070                                               fn_ty,
1071                                               llargs,
1072                                               arg_cleanup_scope,
1073                                               ignore_self)
1074         }
1075         ArgOverloadedOp(lhs, rhs, autoref) => {
1076             assert!(!variadic);
1077
1078             bcx = trans_arg_datum(bcx, arg_tys[0], lhs,
1079                                   arg_cleanup_scope,
1080                                   DontAutorefArg,
1081                                   llargs);
1082
1083             assert_eq!(arg_tys.len(), 1 + rhs.len());
1084             for (rhs, rhs_id) in rhs {
1085                 bcx = trans_arg_datum(bcx, arg_tys[1], rhs,
1086                                       arg_cleanup_scope,
1087                                       if autoref { DoAutorefArg(rhs_id) } else { DontAutorefArg },
1088                                       llargs);
1089             }
1090         }
1091         ArgVals(vs) => {
1092             llargs.push_all(vs);
1093         }
1094     }
1095
1096     bcx
1097 }
1098
1099 #[derive(Copy, Clone)]
1100 pub enum AutorefArg {
1101     DontAutorefArg,
1102     DoAutorefArg(ast::NodeId)
1103 }
1104
1105 pub fn trans_arg_datum<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1106                                    formal_arg_ty: Ty<'tcx>,
1107                                    arg_datum: Datum<'tcx, Expr>,
1108                                    arg_cleanup_scope: cleanup::ScopeId,
1109                                    autoref_arg: AutorefArg,
1110                                    llargs: &mut Vec<ValueRef>)
1111                                    -> Block<'blk, 'tcx> {
1112     let _icx = push_ctxt("trans_arg_datum");
1113     let mut bcx = bcx;
1114     let ccx = bcx.ccx();
1115
1116     debug!("trans_arg_datum({:?})",
1117            formal_arg_ty);
1118
1119     let arg_datum_ty = arg_datum.ty;
1120
1121     debug!("   arg datum: {}", arg_datum.to_string(bcx.ccx()));
1122
1123     let mut val;
1124     // FIXME(#3548) use the adjustments table
1125     match autoref_arg {
1126         DoAutorefArg(arg_id) => {
1127             // We will pass argument by reference
1128             // We want an lvalue, so that we can pass by reference and
1129             let arg_datum = unpack_datum!(
1130                 bcx, arg_datum.to_lvalue_datum(bcx, "arg", arg_id));
1131             val = arg_datum.val;
1132         }
1133         DontAutorefArg if common::type_is_fat_ptr(bcx.tcx(), arg_datum_ty) &&
1134                 !bcx.fcx.type_needs_drop(arg_datum_ty) => {
1135             val = arg_datum.val
1136         }
1137         DontAutorefArg => {
1138             // Make this an rvalue, since we are going to be
1139             // passing ownership.
1140             let arg_datum = unpack_datum!(
1141                 bcx, arg_datum.to_rvalue_datum(bcx, "arg"));
1142
1143             // Now that arg_datum is owned, get it into the appropriate
1144             // mode (ref vs value).
1145             let arg_datum = unpack_datum!(
1146                 bcx, arg_datum.to_appropriate_datum(bcx));
1147
1148             // Technically, ownership of val passes to the callee.
1149             // However, we must cleanup should we panic before the
1150             // callee is actually invoked.
1151             val = arg_datum.add_clean(bcx.fcx, arg_cleanup_scope);
1152         }
1153     }
1154
1155     if type_of::arg_is_indirect(ccx, formal_arg_ty) && formal_arg_ty != arg_datum_ty {
1156         // this could happen due to e.g. subtyping
1157         let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, formal_arg_ty);
1158         debug!("casting actual type ({}) to match formal ({})",
1159                bcx.val_to_string(val), bcx.llty_str(llformal_arg_ty));
1160         debug!("Rust types: {:?}; {:?}", arg_datum_ty,
1161                                      formal_arg_ty);
1162         val = PointerCast(bcx, val, llformal_arg_ty);
1163     }
1164
1165     debug!("--- trans_arg_datum passing {}", bcx.val_to_string(val));
1166
1167     if common::type_is_fat_ptr(bcx.tcx(), formal_arg_ty) {
1168         llargs.push(Load(bcx, expr::get_dataptr(bcx, val)));
1169         llargs.push(Load(bcx, expr::get_len(bcx, val)));
1170     } else {
1171         llargs.push(val);
1172     }
1173
1174     bcx
1175 }