src/abi/mod.rs

   1 //! Handling of everything related to the calling convention. Also fills `fx.local_map`.
   2
   3 #[cfg(debug_assertions)]
   4 mod comments;
   5 mod pass_mode;
   6 mod returning;
   7
   8 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
   9 use rustc_middle::ty::layout::FnAbiExt;
  10 use rustc_target::abi::call::{Conv, FnAbi};
  11 use rustc_target::spec::abi::Abi;
  12
  13 use cranelift_codegen::ir::AbiParam;
  14 use smallvec::smallvec;
  15
  16 use self::pass_mode::*;
  17 use crate::prelude::*;
  18
  19 pub(crate) use self::returning::{can_return_to_ssa_var, codegen_return};
  20
  21 fn clif_sig_from_fn_abi<'tcx>(
  22     tcx: TyCtxt<'tcx>,
  23     triple: &target_lexicon::Triple,
  24     fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
  25 ) -> Signature {
  26     let call_conv = match fn_abi.conv {
  27         Conv::Rust | Conv::C => CallConv::triple_default(triple),
  28         Conv::X86_64SysV => CallConv::SystemV,
  29         Conv::X86_64Win64 => CallConv::WindowsFastcall,
  30         Conv::ArmAapcs
  31         | Conv::Msp430Intr
  32         | Conv::PtxKernel
  33         | Conv::X86Fastcall
  34         | Conv::X86Intr
  35         | Conv::X86Stdcall
  36         | Conv::X86ThisCall
  37         | Conv::X86VectorCall
  38         | Conv::AmdGpuKernel
  39         | Conv::AvrInterrupt
  40         | Conv::AvrNonBlockingInterrupt => {
  41             todo!("{:?}", fn_abi.conv)
  42         }
  43     };
  44     let inputs = fn_abi
  45         .args
  46         .iter()
  47         .map(|arg_abi| arg_abi.get_abi_param(tcx).into_iter())
  48         .flatten();
  49
  50     let (return_ptr, returns) = fn_abi.ret.get_abi_return(tcx);
  51     // Sometimes the first param is an pointer to the place where the return value needs to be stored.
  52     let params: Vec<_> = return_ptr.into_iter().chain(inputs).collect();
  53
  54     Signature {
  55         params,
  56         returns,
  57         call_conv,
  58     }
  59 }
  60
  61 pub(crate) fn get_function_sig<'tcx>(
  62     tcx: TyCtxt<'tcx>,
  63     triple: &target_lexicon::Triple,
  64     inst: Instance<'tcx>,
  65 ) -> Signature {
  66     assert!(!inst.substs.needs_infer());
  67     clif_sig_from_fn_abi(
  68         tcx,
  69         triple,
  70         &FnAbi::of_instance(&RevealAllLayoutCx(tcx), inst, &[]),
  71     )
  72 }
  73
  74 /// Instance must be monomorphized
  75 pub(crate) fn import_function<'tcx>(
  76     tcx: TyCtxt<'tcx>,
  77     module: &mut impl Module,
  78     inst: Instance<'tcx>,
  79 ) -> FuncId {
  80     let name = tcx.symbol_name(inst).name.to_string();
  81     let sig = get_function_sig(tcx, module.isa().triple(), inst);
  82     module
  83         .declare_function(&name, Linkage::Import, &sig)
  84         .unwrap()
  85 }
  86
  87 impl<'tcx, M: Module> FunctionCx<'_, 'tcx, M> {
  88     /// Instance must be monomorphized
  89     pub(crate) fn get_function_ref(&mut self, inst: Instance<'tcx>) -> FuncRef {
  90         let func_id = import_function(self.tcx, &mut self.cx.module, inst);
  91         let func_ref = self
  92             .cx
  93             .module
  94             .declare_func_in_func(func_id, &mut self.bcx.func);
  95
  96         #[cfg(debug_assertions)]
  97         self.add_comment(func_ref, format!("{:?}", inst));
  98
  99         func_ref
 100     }
 101
 102     pub(crate) fn lib_call(
 103         &mut self,
 104         name: &str,
 105         params: Vec<AbiParam>,
 106         returns: Vec<AbiParam>,
 107         args: &[Value],
 108     ) -> &[Value] {
 109         let sig = Signature {
 110             params,
 111             returns,
 112             call_conv: CallConv::triple_default(self.triple()),
 113         };
 114         let func_id = self
 115             .cx
 116             .module
 117             .declare_function(&name, Linkage::Import, &sig)
 118             .unwrap();
 119         let func_ref = self
 120             .cx
 121             .module
 122             .declare_func_in_func(func_id, &mut self.bcx.func);
 123         let call_inst = self.bcx.ins().call(func_ref, args);
 124         #[cfg(debug_assertions)]
 125         {
 126             self.add_comment(call_inst, format!("easy_call {}", name));
 127         }
 128         let results = self.bcx.inst_results(call_inst);
 129         assert!(results.len() <= 2, "{}", results.len());
 130         results
 131     }
 132
 133     pub(crate) fn easy_call(
 134         &mut self,
 135         name: &str,
 136         args: &[CValue<'tcx>],
 137         return_ty: Ty<'tcx>,
 138     ) -> CValue<'tcx> {
 139         let (input_tys, args): (Vec<_>, Vec<_>) = args
 140             .iter()
 141             .map(|arg| {
 142                 (
 143                     AbiParam::new(self.clif_type(arg.layout().ty).unwrap()),
 144                     arg.load_scalar(self),
 145                 )
 146             })
 147             .unzip();
 148         let return_layout = self.layout_of(return_ty);
 149         let return_tys = if let ty::Tuple(tup) = return_ty.kind() {
 150             tup.types()
 151                 .map(|ty| AbiParam::new(self.clif_type(ty).unwrap()))
 152                 .collect()
 153         } else {
 154             vec![AbiParam::new(self.clif_type(return_ty).unwrap())]
 155         };
 156         let ret_vals = self.lib_call(name, input_tys, return_tys, &args);
 157         match *ret_vals {
 158             [] => CValue::by_ref(
 159                 Pointer::const_addr(self, i64::from(self.pointer_type.bytes())),
 160                 return_layout,
 161             ),
 162             [val] => CValue::by_val(val, return_layout),
 163             [val, extra] => CValue::by_val_pair(val, extra, return_layout),
 164             _ => unreachable!(),
 165         }
 166     }
 167 }
 168
 169 /// Make a [`CPlace`] capable of holding value of the specified type.
 170 fn make_local_place<'tcx>(
 171     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 172     local: Local,
 173     layout: TyAndLayout<'tcx>,
 174     is_ssa: bool,
 175 ) -> CPlace<'tcx> {
 176     let place = if is_ssa {
 177         if let rustc_target::abi::Abi::ScalarPair(_, _) = layout.abi {
 178             CPlace::new_var_pair(fx, local, layout)
 179         } else {
 180             CPlace::new_var(fx, local, layout)
 181         }
 182     } else {
 183         CPlace::new_stack_slot(fx, layout)
 184     };
 185
 186     #[cfg(debug_assertions)]
 187     self::comments::add_local_place_comments(fx, place, local);
 188
 189     place
 190 }
 191
 192 pub(crate) fn codegen_fn_prelude<'tcx>(
 193     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 194     start_block: Block,
 195 ) {
 196     fx.bcx.append_block_params_for_function_params(start_block);
 197
 198     fx.bcx.switch_to_block(start_block);
 199     fx.bcx.ins().nop();
 200
 201     let ssa_analyzed = crate::analyze::analyze(fx);
 202
 203     #[cfg(debug_assertions)]
 204     self::comments::add_args_header_comment(fx);
 205
 206     let mut block_params_iter = fx
 207         .bcx
 208         .func
 209         .dfg
 210         .block_params(start_block)
 211         .to_vec()
 212         .into_iter();
 213     let ret_place =
 214         self::returning::codegen_return_param(fx, &ssa_analyzed, &mut block_params_iter);
 215     assert_eq!(fx.local_map.push(ret_place), RETURN_PLACE);
 216
 217     // None means pass_mode == NoPass
 218     enum ArgKind<'tcx> {
 219         Normal(Option<CValue<'tcx>>),
 220         Spread(Vec<Option<CValue<'tcx>>>),
 221     }
 222
 223     let fn_abi = fx.fn_abi.take().unwrap();
 224     let mut arg_abis_iter = fn_abi.args.iter();
 225
 226     let func_params = fx
 227         .mir
 228         .args_iter()
 229         .map(|local| {
 230             let arg_ty = fx.monomorphize(fx.mir.local_decls[local].ty);
 231
 232             // Adapted from https://github.com/rust-lang/rust/blob/145155dc96757002c7b2e9de8489416e2fdbbd57/src/librustc_codegen_llvm/mir/mod.rs#L442-L482
 233             if Some(local) == fx.mir.spread_arg {
 234                 // This argument (e.g. the last argument in the "rust-call" ABI)
 235                 // is a tuple that was spread at the ABI level and now we have
 236                 // to reconstruct it into a tuple local variable, from multiple
 237                 // individual function arguments.
 238
 239                 let tupled_arg_tys = match arg_ty.kind() {
 240                     ty::Tuple(ref tys) => tys,
 241                     _ => bug!("spread argument isn't a tuple?! but {:?}", arg_ty),
 242                 };
 243
 244                 let mut params = Vec::new();
 245                 for (i, _arg_ty) in tupled_arg_tys.types().enumerate() {
 246                     let arg_abi = arg_abis_iter.next().unwrap();
 247                     let param =
 248                         cvalue_for_param(fx, Some(local), Some(i), arg_abi, &mut block_params_iter);
 249                     params.push(param);
 250                 }
 251
 252                 (local, ArgKind::Spread(params), arg_ty)
 253             } else {
 254                 let arg_abi = arg_abis_iter.next().unwrap();
 255                 let param =
 256                     cvalue_for_param(fx, Some(local), None, arg_abi, &mut block_params_iter);
 257                 (local, ArgKind::Normal(param), arg_ty)
 258             }
 259         })
 260         .collect::<Vec<(Local, ArgKind<'tcx>, Ty<'tcx>)>>();
 261
 262     assert!(fx.caller_location.is_none());
 263     if fx.instance.def.requires_caller_location(fx.tcx) {
 264         // Store caller location for `#[track_caller]`.
 265         let arg_abi = arg_abis_iter.next().unwrap();
 266         fx.caller_location =
 267             Some(cvalue_for_param(fx, None, None, arg_abi, &mut block_params_iter).unwrap());
 268     }
 269
 270     assert!(arg_abis_iter.next().is_none(), "ArgAbi left behind");
 271     fx.fn_abi = Some(fn_abi);
 272     assert!(block_params_iter.next().is_none(), "arg_value left behind");
 273
 274     #[cfg(debug_assertions)]
 275     self::comments::add_locals_header_comment(fx);
 276
 277     for (local, arg_kind, ty) in func_params {
 278         let layout = fx.layout_of(ty);
 279
 280         let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 281
 282         // While this is normally an optimization to prevent an unnecessary copy when an argument is
 283         // not mutated by the current function, this is necessary to support unsized arguments.
 284         if let ArgKind::Normal(Some(val)) = arg_kind {
 285             if let Some((addr, meta)) = val.try_to_ptr() {
 286                 let local_decl = &fx.mir.local_decls[local];
 287                 //                       v this ! is important
 288                 let internally_mutable = !val.layout().ty.is_freeze(
 289                     fx.tcx.at(local_decl.source_info.span),
 290                     ParamEnv::reveal_all(),
 291                 );
 292                 if local_decl.mutability == mir::Mutability::Not && !internally_mutable {
 293                     // We wont mutate this argument, so it is fine to borrow the backing storage
 294                     // of this argument, to prevent a copy.
 295
 296                     let place = if let Some(meta) = meta {
 297                         CPlace::for_ptr_with_extra(addr, meta, val.layout())
 298                     } else {
 299                         CPlace::for_ptr(addr, val.layout())
 300                     };
 301
 302                     #[cfg(debug_assertions)]
 303                     self::comments::add_local_place_comments(fx, place, local);
 304
 305                     assert_eq!(fx.local_map.push(place), local);
 306                     continue;
 307                 }
 308             }
 309         }
 310
 311         let place = make_local_place(fx, local, layout, is_ssa);
 312         assert_eq!(fx.local_map.push(place), local);
 313
 314         match arg_kind {
 315             ArgKind::Normal(param) => {
 316                 if let Some(param) = param {
 317                     place.write_cvalue(fx, param);
 318                 }
 319             }
 320             ArgKind::Spread(params) => {
 321                 for (i, param) in params.into_iter().enumerate() {
 322                     if let Some(param) = param {
 323                         place
 324                             .place_field(fx, mir::Field::new(i))
 325                             .write_cvalue(fx, param);
 326                     }
 327                 }
 328             }
 329         }
 330     }
 331
 332     for local in fx.mir.vars_and_temps_iter() {
 333         let ty = fx.monomorphize(fx.mir.local_decls[local].ty);
 334         let layout = fx.layout_of(ty);
 335
 336         let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 337
 338         let place = make_local_place(fx, local, layout, is_ssa);
 339         assert_eq!(fx.local_map.push(place), local);
 340     }
 341
 342     fx.bcx
 343         .ins()
 344         .jump(*fx.block_map.get(START_BLOCK).unwrap(), &[]);
 345 }
 346
 347 pub(crate) fn codegen_terminator_call<'tcx>(
 348     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 349     span: Span,
 350     current_block: Block,
 351     func: &Operand<'tcx>,
 352     args: &[Operand<'tcx>],
 353     destination: Option<(Place<'tcx>, BasicBlock)>,
 354 ) {
 355     let fn_ty = fx.monomorphize(func.ty(fx.mir, fx.tcx));
 356     let fn_sig = fx
 357         .tcx
 358         .normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), fn_ty.fn_sig(fx.tcx));
 359
 360     let destination = destination.map(|(place, bb)| (codegen_place(fx, place), bb));
 361
 362     // Handle special calls like instrinsics and empty drop glue.
 363     let instance = if let ty::FnDef(def_id, substs) = *fn_ty.kind() {
 364         let instance = ty::Instance::resolve(fx.tcx, ty::ParamEnv::reveal_all(), def_id, substs)
 365             .unwrap()
 366             .unwrap()
 367             .polymorphize(fx.tcx);
 368
 369         if fx.tcx.symbol_name(instance).name.starts_with("llvm.") {
 370             crate::intrinsics::codegen_llvm_intrinsic_call(
 371                 fx,
 372                 &fx.tcx.symbol_name(instance).name,
 373                 substs,
 374                 args,
 375                 destination,
 376             );
 377             return;
 378         }
 379
 380         match instance.def {
 381             InstanceDef::Intrinsic(_) => {
 382                 crate::intrinsics::codegen_intrinsic_call(fx, instance, args, destination, span);
 383                 return;
 384             }
 385             InstanceDef::DropGlue(_, None) => {
 386                 // empty drop glue - a nop.
 387                 let (_, dest) = destination.expect("Non terminating drop_in_place_real???");
 388                 let ret_block = fx.get_block(dest);
 389                 fx.bcx.ins().jump(ret_block, &[]);
 390                 return;
 391             }
 392             _ => Some(instance),
 393         }
 394     } else {
 395         None
 396     };
 397
 398     let extra_args = &args[fn_sig.inputs().len()..];
 399     let extra_args = extra_args
 400         .iter()
 401         .map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx)))
 402         .collect::<Vec<_>>();
 403     let fn_abi = if let Some(instance) = instance {
 404         FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), instance, &extra_args)
 405     } else {
 406         FnAbi::of_fn_ptr(
 407             &RevealAllLayoutCx(fx.tcx),
 408             fn_ty.fn_sig(fx.tcx),
 409             &extra_args,
 410         )
 411     };
 412
 413     let is_cold = instance
 414         .map(|inst| {
 415             fx.tcx
 416                 .codegen_fn_attrs(inst.def_id())
 417                 .flags
 418                 .contains(CodegenFnAttrFlags::COLD)
 419         })
 420         .unwrap_or(false);
 421     if is_cold {
 422         fx.cold_blocks.insert(current_block);
 423     }
 424
 425     // Unpack arguments tuple for closures
 426     let args = if fn_sig.abi == Abi::RustCall {
 427         assert_eq!(args.len(), 2, "rust-call abi requires two arguments");
 428         let self_arg = codegen_operand(fx, &args[0]);
 429         let pack_arg = codegen_operand(fx, &args[1]);
 430
 431         let tupled_arguments = match pack_arg.layout().ty.kind() {
 432             ty::Tuple(ref tupled_arguments) => tupled_arguments,
 433             _ => bug!("argument to function with \"rust-call\" ABI is not a tuple"),
 434         };
 435
 436         let mut args = Vec::with_capacity(1 + tupled_arguments.len());
 437         args.push(self_arg);
 438         for i in 0..tupled_arguments.len() {
 439             args.push(pack_arg.value_field(fx, mir::Field::new(i)));
 440         }
 441         args
 442     } else {
 443         args.iter()
 444             .map(|arg| codegen_operand(fx, arg))
 445             .collect::<Vec<_>>()
 446     };
 447
 448     //   | indirect call target
 449     //   |         | the first argument to be passed
 450     //   v         v
 451     let (func_ref, first_arg) = match instance {
 452         // Trait object call
 453         Some(Instance {
 454             def: InstanceDef::Virtual(_, idx),
 455             ..
 456         }) => {
 457             #[cfg(debug_assertions)]
 458             {
 459                 let nop_inst = fx.bcx.ins().nop();
 460                 fx.add_comment(
 461                     nop_inst,
 462                     format!("virtual call; self arg pass mode: {:?}", &fn_abi.args[0],),
 463                 );
 464             }
 465             let (ptr, method) = crate::vtable::get_ptr_and_method_ref(fx, args[0], idx);
 466             (Some(method), smallvec![ptr])
 467         }
 468
 469         // Normal call
 470         Some(_) => (
 471             None,
 472             args.get(0)
 473                 .map(|arg| adjust_arg_for_abi(fx, *arg, &fn_abi.args[0]))
 474                 .unwrap_or(smallvec![]),
 475         ),
 476
 477         // Indirect call
 478         None => {
 479             #[cfg(debug_assertions)]
 480             {
 481                 let nop_inst = fx.bcx.ins().nop();
 482                 fx.add_comment(nop_inst, "indirect call");
 483             }
 484             let func = codegen_operand(fx, func).load_scalar(fx);
 485             (
 486                 Some(func),
 487                 args.get(0)
 488                     .map(|arg| adjust_arg_for_abi(fx, *arg, &fn_abi.args[0]))
 489                     .unwrap_or(smallvec![]),
 490             )
 491         }
 492     };
 493
 494     let ret_place = destination.map(|(place, _)| place);
 495     let (call_inst, call_args) = self::returning::codegen_with_call_return_arg(
 496         fx,
 497         &fn_abi.ret,
 498         ret_place,
 499         |fx, return_ptr| {
 500             let regular_args_count = args.len();
 501             let mut call_args: Vec<Value> = return_ptr
 502                 .into_iter()
 503                 .chain(first_arg.into_iter())
 504                 .chain(
 505                     args.into_iter()
 506                         .enumerate()
 507                         .skip(1)
 508                         .map(|(i, arg)| adjust_arg_for_abi(fx, arg, &fn_abi.args[i]).into_iter())
 509                         .flatten(),
 510                 )
 511                 .collect::<Vec<_>>();
 512
 513             if instance
 514                 .map(|inst| inst.def.requires_caller_location(fx.tcx))
 515                 .unwrap_or(false)
 516             {
 517                 // Pass the caller location for `#[track_caller]`.
 518                 let caller_location = fx.get_caller_location(span);
 519                 call_args.extend(
 520                     adjust_arg_for_abi(fx, caller_location, &fn_abi.args[regular_args_count])
 521                         .into_iter(),
 522                 );
 523                 assert_eq!(fn_abi.args.len(), regular_args_count + 1);
 524             } else {
 525                 assert_eq!(fn_abi.args.len(), regular_args_count);
 526             }
 527
 528             let call_inst = if let Some(func_ref) = func_ref {
 529                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
 530                 let sig = fx.bcx.import_signature(sig);
 531                 fx.bcx.ins().call_indirect(sig, func_ref, &call_args)
 532             } else {
 533                 let func_ref =
 534                     fx.get_function_ref(instance.expect("non-indirect call on non-FnDef type"));
 535                 fx.bcx.ins().call(func_ref, &call_args)
 536             };
 537
 538             (call_inst, call_args)
 539         },
 540     );
 541
 542     // FIXME find a cleaner way to support varargs
 543     if fn_sig.c_variadic {
 544         if fn_sig.abi != Abi::C {
 545             fx.tcx.sess.span_fatal(
 546                 span,
 547                 &format!("Variadic call for non-C abi {:?}", fn_sig.abi),
 548             );
 549         }
 550         let sig_ref = fx.bcx.func.dfg.call_signature(call_inst).unwrap();
 551         let abi_params = call_args
 552             .into_iter()
 553             .map(|arg| {
 554                 let ty = fx.bcx.func.dfg.value_type(arg);
 555                 if !ty.is_int() {
 556                     // FIXME set %al to upperbound on float args once floats are supported
 557                     fx.tcx
 558                         .sess
 559                         .span_fatal(span, &format!("Non int ty {:?} for variadic call", ty));
 560                 }
 561                 AbiParam::new(ty)
 562             })
 563             .collect::<Vec<AbiParam>>();
 564         fx.bcx.func.dfg.signatures[sig_ref].params = abi_params;
 565     }
 566
 567     if let Some((_, dest)) = destination {
 568         let ret_block = fx.get_block(dest);
 569         fx.bcx.ins().jump(ret_block, &[]);
 570     } else {
 571         trap_unreachable(fx, "[corruption] Diverging function returned");
 572     }
 573 }
 574
 575 pub(crate) fn codegen_drop<'tcx>(
 576     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 577     span: Span,
 578     drop_place: CPlace<'tcx>,
 579 ) {
 580     let ty = drop_place.layout().ty;
 581     let drop_instance = Instance::resolve_drop_in_place(fx.tcx, ty).polymorphize(fx.tcx);
 582
 583     if let ty::InstanceDef::DropGlue(_, None) = drop_instance.def {
 584         // we don't actually need to drop anything
 585     } else {
 586         match ty.kind() {
 587             ty::Dynamic(..) => {
 588                 let (ptr, vtable) = drop_place.to_ptr_maybe_unsized();
 589                 let ptr = ptr.get_addr(fx);
 590                 let drop_fn = crate::vtable::drop_fn_of_obj(fx, vtable.unwrap());
 591
 592                 // FIXME(eddyb) perhaps move some of this logic into
 593                 // `Instance::resolve_drop_in_place`?
 594                 let virtual_drop = Instance {
 595                     def: ty::InstanceDef::Virtual(drop_instance.def_id(), 0),
 596                     substs: drop_instance.substs,
 597                 };
 598                 let fn_abi = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), virtual_drop, &[]);
 599
 600                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
 601                 let sig = fx.bcx.import_signature(sig);
 602                 fx.bcx.ins().call_indirect(sig, drop_fn, &[ptr]);
 603             }
 604             _ => {
 605                 assert!(!matches!(drop_instance.def, InstanceDef::Virtual(_, _)));
 606
 607                 let fn_abi = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), drop_instance, &[]);
 608
 609                 let arg_value = drop_place.place_ref(
 610                     fx,
 611                     fx.layout_of(fx.tcx.mk_ref(
 612                         &ty::RegionKind::ReErased,
 613                         TypeAndMut {
 614                             ty,
 615                             mutbl: crate::rustc_hir::Mutability::Mut,
 616                         },
 617                     )),
 618                 );
 619                 let arg_value = adjust_arg_for_abi(fx, arg_value, &fn_abi.args[0]);
 620
 621                 let mut call_args: Vec<Value> = arg_value.into_iter().collect::<Vec<_>>();
 622
 623                 if drop_instance.def.requires_caller_location(fx.tcx) {
 624                     // Pass the caller location for `#[track_caller]`.
 625                     let caller_location = fx.get_caller_location(span);
 626                     call_args.extend(
 627                         adjust_arg_for_abi(fx, caller_location, &fn_abi.args[1]).into_iter(),
 628                     );
 629                 }
 630
 631                 let func_ref = fx.get_function_ref(drop_instance);
 632                 fx.bcx.ins().call(func_ref, &call_args);
 633             }
 634         }
 635     }
 636 }