src/abi.rs

   1 use std::iter;
   2
   3 use rustc::hir;
   4 use rustc_target::spec::abi::Abi;
   5
   6 use crate::prelude::*;
   7
   8 pub fn cton_sig_from_fn_ty<'a, 'tcx: 'a>(
   9     tcx: TyCtxt<'a, 'tcx, 'tcx>,
  10     fn_ty: Ty<'tcx>,
  11 ) -> Signature {
  12     let sig = ty_fn_sig(tcx, fn_ty);
  13     assert!(!sig.variadic, "Variadic function are not yet supported");
  14     let (call_conv, inputs, _output): (CallConv, Vec<Ty>, Ty) = match sig.abi {
  15         Abi::Rust => (CallConv::Fast, sig.inputs().to_vec(), sig.output()),
  16         Abi::C => (CallConv::SystemV, sig.inputs().to_vec(), sig.output()),
  17         Abi::RustCall => {
  18             println!(
  19                 "rust-call sig: {:?} inputs: {:?} output: {:?}",
  20                 sig,
  21                 sig.inputs(),
  22                 sig.output()
  23             );
  24             assert_eq!(sig.inputs().len(), 2);
  25             let extra_args = match sig.inputs().last().unwrap().sty {
  26                 ty::TyTuple(ref tupled_arguments) => tupled_arguments,
  27                 _ => bug!("argument to function with \"rust-call\" ABI is not a tuple"),
  28             };
  29             let mut inputs: Vec<Ty> = vec![sig.inputs()[0]];
  30             inputs.extend(extra_args.into_iter());
  31             (CallConv::Fast, inputs, sig.output())
  32         }
  33         Abi::System => bug!("system abi should be selected elsewhere"),
  34         Abi::RustIntrinsic => (CallConv::SystemV, sig.inputs().to_vec(), sig.output()),
  35         _ => unimplemented!("unsupported abi {:?}", sig.abi),
  36     };
  37     Signature {
  38         params: Some(types::I64).into_iter() // First param is place to put return val
  39             .chain(inputs.into_iter().map(|ty| {
  40                 let cton_ty = cton_type_from_ty(tcx, ty);
  41                 if let Some(cton_ty) = cton_ty {
  42                     cton_ty
  43                 } else {
  44                     if sig.abi == Abi::C {
  45                         unimplemented!("Non scalars are not yet supported for \"C\" abi");
  46                     }
  47                     types::I64
  48                 }
  49             }))
  50             .map(AbiParam::new).collect(),
  51         returns: vec![],
  52         call_conv,
  53         argument_bytes: None,
  54     }
  55 }
  56
  57 fn ty_fn_sig<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> ty::FnSig<'tcx> {
  58     let sig = match ty.sty {
  59         ty::TyFnDef(..) |
  60         // Shims currently have type TyFnPtr. Not sure this should remain.
  61         ty::TyFnPtr(_) => ty.fn_sig(tcx),
  62         ty::TyClosure(def_id, substs) => {
  63             let sig = substs.closure_sig(def_id, tcx);
  64
  65             let env_ty = tcx.closure_env_ty(def_id, substs).unwrap();
  66             sig.map_bound(|sig| tcx.mk_fn_sig(
  67                 iter::once(*env_ty.skip_binder()).chain(sig.inputs().iter().cloned()),
  68                 sig.output(),
  69                 sig.variadic,
  70                 sig.unsafety,
  71                 sig.abi
  72             ))
  73         }
  74         ty::TyGenerator(def_id, substs, _) => {
  75             let sig = substs.poly_sig(def_id, tcx);
  76
  77             let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv);
  78             let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
  79
  80             sig.map_bound(|sig| {
  81                 let state_did = tcx.lang_items().gen_state().unwrap();
  82                 let state_adt_ref = tcx.adt_def(state_did);
  83                 let state_substs = tcx.intern_substs(&[
  84                     sig.yield_ty.into(),
  85                     sig.return_ty.into(),
  86                 ]);
  87                 let ret_ty = tcx.mk_adt(state_adt_ref, state_substs);
  88
  89                 tcx.mk_fn_sig(iter::once(env_ty),
  90                     ret_ty,
  91                     false,
  92                     hir::Unsafety::Normal,
  93                     Abi::Rust
  94                 )
  95             })
  96         }
  97         _ => bug!("unexpected type {:?} to ty_fn_sig", ty)
  98     };
  99     tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), &sig)
 100 }
 101
 102 impl<'a, 'tcx: 'a> FunctionCx<'a, 'tcx> {
 103     /// Instance must be monomorphized
 104     pub fn get_function_ref(&mut self, inst: Instance<'tcx>) -> FuncRef {
 105         assert!(!inst.substs.needs_infer() && !inst.substs.has_param_types());
 106         let fn_ty = inst.ty(self.tcx);
 107         let sig = cton_sig_from_fn_ty(self.tcx, fn_ty);
 108         let def_path_based_names =
 109             ::rustc_mir::monomorphize::item::DefPathBasedNames::new(self.tcx, false, false);
 110         let mut name = String::new();
 111         def_path_based_names.push_instance_as_string(inst, &mut name);
 112         let func_id = self
 113             .module
 114             .declare_function(&name, Linkage::Import, &sig)
 115             .unwrap();
 116         self.module
 117             .declare_func_in_func(func_id, &mut self.bcx.func)
 118     }
 119
 120     fn lib_call(
 121         &mut self,
 122         name: &str,
 123         input_tys: Vec<types::Type>,
 124         output_ty: Option<types::Type>,
 125         args: &[Value],
 126     ) -> Option<Value> {
 127         let sig = Signature {
 128             params: input_tys.iter().cloned().map(AbiParam::new).collect(),
 129             returns: vec![AbiParam::new(output_ty.unwrap_or(types::VOID))],
 130             call_conv: CallConv::SystemV,
 131             argument_bytes: None,
 132         };
 133         let func_id = self
 134             .module
 135             .declare_function(&name, Linkage::Import, &sig)
 136             .unwrap();
 137         let func_ref = self
 138             .module
 139             .declare_func_in_func(func_id, &mut self.bcx.func);
 140         let call_inst = self.bcx.ins().call(func_ref, args);
 141         if output_ty.is_none() {
 142             return None;
 143         }
 144         let results = self.bcx.inst_results(call_inst);
 145         assert_eq!(results.len(), 1);
 146         Some(results[0])
 147     }
 148
 149     pub fn easy_call(
 150         &mut self,
 151         name: &str,
 152         args: &[CValue<'tcx>],
 153         return_ty: Ty<'tcx>,
 154     ) -> CValue<'tcx> {
 155         let (input_tys, args): (Vec<_>, Vec<_>) = args
 156             .into_iter()
 157             .map(|arg| {
 158                 (
 159                     self.cton_type(arg.layout().ty).unwrap(),
 160                     arg.load_value(self),
 161                 )
 162             }).unzip();
 163         let return_layout = self.layout_of(return_ty);
 164         let return_ty = if let TypeVariants::TyTuple(tup) = return_ty.sty {
 165             if !tup.is_empty() {
 166                 bug!("easy_call( (...) -> <non empty tuple> ) is not allowed");
 167             }
 168             None
 169         } else {
 170             Some(self.cton_type(return_ty).unwrap())
 171         };
 172         if let Some(val) = self.lib_call(name, input_tys, return_ty, &args) {
 173             CValue::ByVal(val, return_layout)
 174         } else {
 175             CValue::ByRef(self.bcx.ins().iconst(types::I64, 0), return_layout)
 176         }
 177     }
 178
 179     fn self_sig(&self) -> FnSig<'tcx> {
 180         ty_fn_sig(self.tcx, self.instance.ty(self.tcx))
 181     }
 182
 183     fn return_type(&self) -> Ty<'tcx> {
 184         self.self_sig().output()
 185     }
 186 }
 187
 188 pub fn codegen_fn_prelude<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx>, start_ebb: Ebb) {
 189     let ssa_analyzed = crate::analyze::analyze(fx);
 190     fx.tcx.sess.warn(&format!("ssa {:?}", ssa_analyzed));
 191
 192     match fx.self_sig().abi {
 193         Abi::Rust | Abi::RustCall => {}
 194         _ => unimplemented!("declared function with non \"rust\" or \"rust-call\" abi"),
 195     }
 196
 197     let ret_param = fx.bcx.append_ebb_param(start_ebb, types::I64);
 198
 199     enum ArgKind {
 200         Normal(Value),
 201         Spread(Vec<Value>),
 202     }
 203
 204     let func_params = fx.mir.args_iter().map(|local| {
 205         let arg_ty = fx.monomorphize(&fx.mir.local_decls[local].ty);
 206
 207         // Adapted from https://github.com/rust-lang/rust/blob/145155dc96757002c7b2e9de8489416e2fdbbd57/src/librustc_codegen_llvm/mir/mod.rs#L442-L482
 208         if Some(local) == fx.mir.spread_arg {
 209             // This argument (e.g. the last argument in the "rust-call" ABI)
 210             // is a tuple that was spread at the ABI level and now we have
 211             // to reconstruct it into a tuple local variable, from multiple
 212             // individual function arguments.
 213
 214             let tupled_arg_tys = match arg_ty.sty {
 215                 ty::TyTuple(ref tys) => tys,
 216                 _ => bug!("spread argument isn't a tuple?! but {:?}", arg_ty),
 217             };
 218
 219             let mut ebb_params = Vec::new();
 220             for arg_ty in tupled_arg_tys.iter() {
 221                 let cton_type = fx.cton_type(arg_ty).unwrap_or(types::I64);
 222                 ebb_params.push(fx.bcx.append_ebb_param(start_ebb, cton_type));
 223             }
 224
 225             (local, ArgKind::Spread(ebb_params), arg_ty)
 226         } else {
 227             let cton_type = fx.cton_type(arg_ty).unwrap_or(types::I64);
 228             (local, ArgKind::Normal(fx.bcx.append_ebb_param(start_ebb, cton_type)), arg_ty)
 229         }
 230     }).collect::<Vec<(Local, ArgKind, Ty)>>();
 231
 232     let ret_layout = fx.layout_of(fx.return_type());
 233     fx.local_map
 234         .insert(RETURN_PLACE, CPlace::Addr(ret_param, ret_layout));
 235
 236     for (local, arg_kind, ty) in func_params {
 237         let layout = fx.layout_of(ty);
 238
 239         if let ArgKind::Normal(ebb_param) = arg_kind {
 240             if !ssa_analyzed
 241                 .get(&local)
 242                 .unwrap()
 243                 .contains(crate::analyze::Flags::NOT_SSA)
 244             {
 245                 let var = Variable(local);
 246                 fx.bcx.declare_var(var, fx.cton_type(ty).unwrap());
 247                 fx.bcx.def_var(var, ebb_param);
 248                 fx.local_map.insert(local, CPlace::Var(var, layout));
 249                 continue;
 250             }
 251         }
 252
 253         let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
 254             kind: StackSlotKind::ExplicitSlot,
 255             size: layout.size.bytes() as u32,
 256             offset: None,
 257         });
 258
 259         let place = CPlace::from_stack_slot(fx, stack_slot, ty);
 260
 261         match arg_kind {
 262             ArgKind::Normal(ebb_param) => {
 263                 if fx.cton_type(ty).is_some() {
 264                     place.write_cvalue(fx, CValue::ByVal(ebb_param, place.layout()));
 265                 } else {
 266                     place.write_cvalue(fx, CValue::ByRef(ebb_param, place.layout()));
 267                 }
 268             }
 269             ArgKind::Spread(ebb_params) => {
 270                 for (i, ebb_param) in ebb_params.into_iter().enumerate() {
 271                     let sub_place = place.place_field(fx, mir::Field::new(i));
 272                     if fx.cton_type(sub_place.layout().ty).is_some() {
 273                         sub_place.write_cvalue(fx, CValue::ByVal(ebb_param, sub_place.layout()));
 274                     } else {
 275                         sub_place.write_cvalue(fx, CValue::ByRef(ebb_param, sub_place.layout()));
 276                     }
 277                 }
 278             }
 279         }
 280         fx.local_map.insert(local, place);
 281     }
 282
 283     for local in fx.mir.vars_and_temps_iter() {
 284         let ty = fx.mir.local_decls[local].ty;
 285         let layout = fx.layout_of(ty);
 286
 287         let place = if ssa_analyzed
 288             .get(&local)
 289             .unwrap()
 290             .contains(crate::analyze::Flags::NOT_SSA)
 291         {
 292             let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
 293                 kind: StackSlotKind::ExplicitSlot,
 294                 size: layout.size.bytes() as u32,
 295                 offset: None,
 296             });
 297             CPlace::from_stack_slot(fx, stack_slot, ty)
 298         } else {
 299             let var = Variable(local);
 300             fx.bcx.declare_var(var, fx.cton_type(ty).unwrap());
 301             CPlace::Var(var, layout)
 302         };
 303
 304         fx.local_map.insert(local, place);
 305     }
 306 }
 307
 308 pub fn codegen_call<'a, 'tcx: 'a>(
 309     fx: &mut FunctionCx<'a, 'tcx>,
 310     func: &Operand<'tcx>,
 311     args: &[Operand<'tcx>],
 312     destination: &Option<(Place<'tcx>, BasicBlock)>,
 313 ) {
 314     let func = trans_operand(fx, func);
 315     let fn_ty = func.layout().ty;
 316     let sig = ty_fn_sig(fx.tcx, fn_ty);
 317
 318     // Unpack arguments tuple for closures
 319     let args = if sig.abi == Abi::RustCall {
 320         assert_eq!(args.len(), 2, "rust-call abi requires two arguments");
 321         let self_arg = trans_operand(fx, &args[0]);
 322         let pack_arg = trans_operand(fx, &args[1]);
 323         let mut args = Vec::new();
 324         args.push(self_arg);
 325         match pack_arg.layout().ty.sty {
 326             ty::TyTuple(ref tupled_arguments) => {
 327                 for (i, _) in tupled_arguments.iter().enumerate() {
 328                     args.push(pack_arg.value_field(fx, mir::Field::new(i)));
 329                 }
 330             }
 331             _ => bug!("argument to function with \"rust-call\" ABI is not a tuple"),
 332         }
 333         println!(
 334             "{:?} {:?}",
 335             pack_arg.layout().ty,
 336             args.iter().map(|a| a.layout().ty).collect::<Vec<_>>()
 337         );
 338         args
 339     } else {
 340         args.into_iter()
 341             .map(|arg| trans_operand(fx, arg))
 342             .collect::<Vec<_>>()
 343     };
 344
 345     let destination = destination.as_ref().map(|(place, bb)| {
 346         (trans_place(fx, place), *bb)
 347     });
 348
 349     if codegen_intrinsic_call(fx, fn_ty, sig, &args, destination) {
 350         return;
 351     }
 352
 353     let return_ptr = match destination {
 354         Some((place, _)) => place.expect_addr(),
 355         None => fx.bcx.ins().iconst(types::I64, 0),
 356     };
 357
 358     let call_args = Some(return_ptr)
 359         .into_iter()
 360         .chain(args.into_iter().map(|arg| {
 361             if fx.cton_type(arg.layout().ty).is_some() {
 362                 arg.load_value(fx)
 363             } else {
 364                 arg.force_stack(fx)
 365             }
 366         })).collect::<Vec<_>>();
 367
 368     match func {
 369         CValue::Func(func, _) => {
 370             fx.bcx.ins().call(func, &call_args);
 371         }
 372         func => {
 373             let func_ty = func.layout().ty;
 374             let func = func.load_value(fx);
 375             let sig = fx
 376                 .bcx
 377                 .import_signature(cton_sig_from_fn_ty(fx.tcx, func_ty));
 378             fx.bcx.ins().call_indirect(sig, func, &call_args);
 379         }
 380     }
 381     if let Some((_, dest)) = destination {
 382         let ret_ebb = fx.get_ebb(dest);
 383         fx.bcx.ins().jump(ret_ebb, &[]);
 384     } else {
 385         fx.bcx.ins().trap(TrapCode::User(!0));
 386     }
 387 }
 388
 389 fn codegen_intrinsic_call<'a, 'tcx: 'a>(
 390     fx: &mut FunctionCx<'a, 'tcx>,
 391     fn_ty: Ty<'tcx>,
 392     sig: FnSig<'tcx>,
 393     args: &[CValue<'tcx>],
 394     destination: Option<(CPlace<'tcx>, BasicBlock)>,
 395 ) -> bool {
 396     if let TypeVariants::TyFnDef(def_id, substs) = fn_ty.sty {
 397         if sig.abi == Abi::RustIntrinsic {
 398             let intrinsic = fx.tcx.item_name(def_id).as_str();
 399             let intrinsic = &intrinsic[..];
 400
 401             let ret = match destination {
 402                 Some((place, _)) => place,
 403                 None => {
 404                     println!(
 405                         "codegen_call(fx, _, {:?}, {:?})",
 406                         args, destination
 407                     );
 408                     // Insert non returning intrinsics here
 409                     match intrinsic {
 410                         "abort" => {
 411                             fx.bcx.ins().trap(TrapCode::User(!0 - 1));
 412                         }
 413                         "unreachable" => {
 414                             fx.bcx.ins().trap(TrapCode::User(!0 - 1));
 415                         }
 416                         _ => unimplemented!("unsupported instrinsic {}", intrinsic),
 417                     }
 418                     return true;
 419                 }
 420             };
 421
 422             let nil_ty = fx.tcx.mk_nil();
 423             let u64_layout = fx.layout_of(fx.tcx.types.u64);
 424             let usize_layout = fx.layout_of(fx.tcx.types.usize);
 425
 426             match intrinsic {
 427                 "assume" => {
 428                     assert_eq!(args.len(), 1);
 429                 }
 430                 "arith_offset" => {
 431                     assert_eq!(args.len(), 2);
 432                     let base = args[0].load_value(fx);
 433                     let offset = args[1].load_value(fx);
 434                     let res = fx.bcx.ins().iadd(base, offset);
 435                     let res = CValue::ByVal(res, ret.layout());
 436                     ret.write_cvalue(fx, res);
 437                 }
 438                 "likely" | "unlikely" => {
 439                     assert_eq!(args.len(), 1);
 440                     ret.write_cvalue(fx, args[0]);
 441                 }
 442                 "copy" | "copy_nonoverlapping" => {
 443                     let elem_ty = substs.type_at(0);
 444                     let elem_size: u64 = fx.layout_of(elem_ty).size.bytes();
 445                     let elem_size = fx.bcx.ins().iconst(types::I64, elem_size as i64);
 446                     assert_eq!(args.len(), 3);
 447                     let src = args[0];
 448                     let dst = args[1];
 449                     let count = args[2].load_value(fx);
 450                     let byte_amount = fx.bcx.ins().imul(count, elem_size);
 451                     fx.easy_call(
 452                         "memmove",
 453                         &[dst, src, CValue::ByVal(byte_amount, usize_layout)],
 454                         nil_ty,
 455                     );
 456                 }
 457                 "discriminant_value" => {
 458                     assert_eq!(args.len(), 1);
 459                     let discr = crate::base::trans_get_discriminant(fx, args[0], ret.layout());
 460                     ret.write_cvalue(fx, discr);
 461                 }
 462                 "size_of" => {
 463                     assert_eq!(args.len(), 0);
 464                     let size_of = fx.layout_of(substs.type_at(0)).size.bytes();
 465                     let size_of = CValue::const_val(fx, usize_layout.ty, size_of as i64);
 466                     ret.write_cvalue(fx, size_of);
 467                 }
 468                 "type_id" => {
 469                     assert_eq!(args.len(), 0);
 470                     let type_id = fx.tcx.type_id_hash(substs.type_at(0));
 471                     let type_id = CValue::const_val(fx, u64_layout.ty, type_id as i64);
 472                     ret.write_cvalue(fx, type_id);
 473                 }
 474                 "min_align_of" => {
 475                     assert_eq!(args.len(), 0);
 476                     let min_align = fx.layout_of(substs.type_at(0)).align.abi();
 477                     let min_align = CValue::const_val(fx, usize_layout.ty, min_align as i64);
 478                     ret.write_cvalue(fx, min_align);
 479                 }
 480                 _ if intrinsic.starts_with("unchecked_") => {
 481                     assert_eq!(args.len(), 2);
 482                     let bin_op = match intrinsic {
 483                         "unchecked_div" => BinOp::Div,
 484                         "unchecked_rem" => BinOp::Rem,
 485                         "unchecked_shl" => BinOp::Shl,
 486                         "unchecked_shr" => BinOp::Shr,
 487                         _ => unimplemented!("intrinsic {}", intrinsic),
 488                     };
 489                     let res = match ret.layout().ty.sty {
 490                         TypeVariants::TyUint(_) => crate::base::trans_int_binop(
 491                             fx,
 492                             bin_op,
 493                             args[0],
 494                             args[1],
 495                             ret.layout().ty,
 496                             false,
 497                         ),
 498                         TypeVariants::TyInt(_) => crate::base::trans_int_binop(
 499                             fx,
 500                             bin_op,
 501                             args[0],
 502                             args[1],
 503                             ret.layout().ty,
 504                             true,
 505                         ),
 506                         _ => panic!(),
 507                     };
 508                     ret.write_cvalue(fx, res);
 509                 }
 510                 _ if intrinsic.ends_with("_with_overflow") => {
 511                     assert_eq!(args.len(), 2);
 512                     assert_eq!(args[0].layout().ty, args[1].layout().ty);
 513                     let bin_op = match intrinsic {
 514                         "add_with_overflow" => BinOp::Add,
 515                         "sub_with_overflow" => BinOp::Sub,
 516                         "mul_with_overflow" => BinOp::Mul,
 517                         _ => unimplemented!("intrinsic {}", intrinsic),
 518                     };
 519                     let res = match args[0].layout().ty.sty {
 520                         TypeVariants::TyUint(_) => crate::base::trans_checked_int_binop(
 521                             fx,
 522                             bin_op,
 523                             args[0],
 524                             args[1],
 525                             ret.layout().ty,
 526                             false,
 527                         ),
 528                         TypeVariants::TyInt(_) => crate::base::trans_checked_int_binop(
 529                             fx,
 530                             bin_op,
 531                             args[0],
 532                             args[1],
 533                             ret.layout().ty,
 534                             true,
 535                         ),
 536                         _ => panic!(),
 537                     };
 538                     ret.write_cvalue(fx, res);
 539                 }
 540                 _ if intrinsic.starts_with("overflowing_") => {
 541                     assert_eq!(args.len(), 2);
 542                     assert_eq!(args[0].layout().ty, args[1].layout().ty);
 543                     let bin_op = match intrinsic {
 544                         "overflowing_add" => BinOp::Add,
 545                         "overflowing_sub" => BinOp::Sub,
 546                         "overflowing_mul" => BinOp::Mul,
 547                         _ => unimplemented!("intrinsic {}", intrinsic),
 548                     };
 549                     let res = match args[0].layout().ty.sty {
 550                         TypeVariants::TyUint(_) => crate::base::trans_int_binop(
 551                             fx,
 552                             bin_op,
 553                             args[0],
 554                             args[1],
 555                             ret.layout().ty,
 556                             false,
 557                         ),
 558                         TypeVariants::TyInt(_) => crate::base::trans_int_binop(
 559                             fx,
 560                             bin_op,
 561                             args[0],
 562                             args[1],
 563                             ret.layout().ty,
 564                             true,
 565                         ),
 566                         _ => panic!(),
 567                     };
 568                     ret.write_cvalue(fx, res);
 569                 }
 570                 "offset" => {
 571                     assert_eq!(args.len(), 2);
 572                     let base = args[0].load_value(fx);
 573                     let offset = args[1].load_value(fx);
 574                     let res = fx.bcx.ins().iadd(base, offset);
 575                     ret.write_cvalue(fx, CValue::ByVal(res, args[0].layout()));
 576                 }
 577                 "transmute" => {
 578                     assert_eq!(args.len(), 1);
 579                     let src_ty = substs.type_at(0);
 580                     let dst_ty = substs.type_at(1);
 581                     assert_eq!(args[0].layout().ty, src_ty);
 582                     let addr = args[0].force_stack(fx);
 583                     let dst_layout = fx.layout_of(dst_ty);
 584                     ret.write_cvalue(fx, CValue::ByRef(addr, dst_layout))
 585                 }
 586                 "uninit" => {
 587                     assert_eq!(args.len(), 0);
 588                     let ty = substs.type_at(0);
 589                     let layout = fx.layout_of(ty);
 590                     let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
 591                         kind: StackSlotKind::ExplicitSlot,
 592                         size: layout.size.bytes() as u32,
 593                         offset: None,
 594                     });
 595
 596                     let uninit_place = CPlace::from_stack_slot(fx, stack_slot, ty);
 597                     let uninit_val = uninit_place.to_cvalue(fx);
 598                     ret.write_cvalue(fx, uninit_val);
 599                 }
 600                 "ctlz" | "ctlz_nonzero" => {
 601                     assert_eq!(args.len(), 1);
 602                     let arg = args[0].load_value(fx);
 603                     let res = CValue::ByVal(fx.bcx.ins().clz(arg), args[0].layout());
 604                     ret.write_cvalue(fx, res);
 605                 }
 606                 "cttz" | "cttz_nonzero" => {
 607                     assert_eq!(args.len(), 1);
 608                     let arg = args[0].load_value(fx);
 609                     let res = CValue::ByVal(fx.bcx.ins().clz(arg), args[0].layout());
 610                     ret.write_cvalue(fx, res);
 611                 }
 612                 "ctpop" => {
 613                     assert_eq!(args.len(), 1);
 614                     let arg = args[0].load_value(fx);
 615                     let res = CValue::ByVal(fx.bcx.ins().popcnt(arg), args[0].layout());
 616                     ret.write_cvalue(fx, res);
 617                 }
 618                 _ => unimpl!("unsupported intrinsic {}", intrinsic),
 619             }
 620
 621             if let Some((_, dest)) = destination {
 622                 let ret_ebb = fx.get_ebb(dest);
 623                 fx.bcx.ins().jump(ret_ebb, &[]);
 624             } else {
 625                 fx.bcx.ins().trap(TrapCode::User(!0));
 626             }
 627             return true;
 628         }
 629     }
 630
 631     false
 632 }