compiler/rustc_codegen_cranelift/src/abi/mod.rs

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