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::CCmseNonSecureCall
  32         | Conv::Msp430Intr
  33         | Conv::PtxKernel
  34         | Conv::X86Fastcall
  35         | Conv::X86Intr
  36         | Conv::X86Stdcall
  37         | Conv::X86ThisCall
  38         | Conv::X86VectorCall
  39         | Conv::AmdGpuKernel
  40         | Conv::AvrInterrupt
  41         | Conv::AvrNonBlockingInterrupt => todo!("{:?}", fn_abi.conv),
  42     };
  43     let inputs = fn_abi.args.iter().map(|arg_abi| arg_abi.get_abi_param(tcx).into_iter()).flatten();
  44
  45     let (return_ptr, returns) = fn_abi.ret.get_abi_return(tcx);
  46     // Sometimes the first param is an pointer to the place where the return value needs to be stored.
  47     let params: Vec<_> = return_ptr.into_iter().chain(inputs).collect();
  48
  49     Signature { params, returns, call_conv }
  50 }
  51
  52 pub(crate) fn get_function_sig<'tcx>(
  53     tcx: TyCtxt<'tcx>,
  54     triple: &target_lexicon::Triple,
  55     inst: Instance<'tcx>,
  56 ) -> Signature {
  57     assert!(!inst.substs.needs_infer());
  58     clif_sig_from_fn_abi(tcx, triple, &FnAbi::of_instance(&RevealAllLayoutCx(tcx), inst, &[]))
  59 }
  60
  61 /// Instance must be monomorphized
  62 pub(crate) fn import_function<'tcx>(
  63     tcx: TyCtxt<'tcx>,
  64     module: &mut dyn Module,
  65     inst: Instance<'tcx>,
  66 ) -> FuncId {
  67     let name = tcx.symbol_name(inst).name.to_string();
  68     let sig = get_function_sig(tcx, module.isa().triple(), inst);
  69     module.declare_function(&name, Linkage::Import, &sig).unwrap()
  70 }
  71
  72 impl<'tcx> FunctionCx<'_, '_, 'tcx> {
  73     /// Instance must be monomorphized
  74     pub(crate) fn get_function_ref(&mut self, inst: Instance<'tcx>) -> FuncRef {
  75         let func_id = import_function(self.tcx, self.cx.module, inst);
  76         let func_ref = self.cx.module.declare_func_in_func(func_id, &mut self.bcx.func);
  77
  78         #[cfg(debug_assertions)]
  79         self.add_comment(func_ref, format!("{:?}", inst));
  80
  81         func_ref
  82     }
  83
  84     pub(crate) fn lib_call(
  85         &mut self,
  86         name: &str,
  87         params: Vec<AbiParam>,
  88         returns: Vec<AbiParam>,
  89         args: &[Value],
  90     ) -> &[Value] {
  91         let sig = Signature { params, returns, call_conv: CallConv::triple_default(self.triple()) };
  92         let func_id = self.cx.module.declare_function(&name, Linkage::Import, &sig).unwrap();
  93         let func_ref = self.cx.module.declare_func_in_func(func_id, &mut self.bcx.func);
  94         let call_inst = self.bcx.ins().call(func_ref, args);
  95         #[cfg(debug_assertions)]
  96         {
  97             self.add_comment(call_inst, format!("easy_call {}", name));
  98         }
  99         let results = self.bcx.inst_results(call_inst);
 100         assert!(results.len() <= 2, "{}", results.len());
 101         results
 102     }
 103
 104     pub(crate) fn easy_call(
 105         &mut self,
 106         name: &str,
 107         args: &[CValue<'tcx>],
 108         return_ty: Ty<'tcx>,
 109     ) -> CValue<'tcx> {
 110         let (input_tys, args): (Vec<_>, Vec<_>) = args
 111             .iter()
 112             .map(|arg| {
 113                 (AbiParam::new(self.clif_type(arg.layout().ty).unwrap()), arg.load_scalar(self))
 114             })
 115             .unzip();
 116         let return_layout = self.layout_of(return_ty);
 117         let return_tys = if let ty::Tuple(tup) = return_ty.kind() {
 118             tup.types().map(|ty| AbiParam::new(self.clif_type(ty).unwrap())).collect()
 119         } else {
 120             vec![AbiParam::new(self.clif_type(return_ty).unwrap())]
 121         };
 122         let ret_vals = self.lib_call(name, input_tys, return_tys, &args);
 123         match *ret_vals {
 124             [] => CValue::by_ref(
 125                 Pointer::const_addr(self, i64::from(self.pointer_type.bytes())),
 126                 return_layout,
 127             ),
 128             [val] => CValue::by_val(val, return_layout),
 129             [val, extra] => CValue::by_val_pair(val, extra, return_layout),
 130             _ => unreachable!(),
 131         }
 132     }
 133 }
 134
 135 /// Make a [`CPlace`] capable of holding value of the specified type.
 136 fn make_local_place<'tcx>(
 137     fx: &mut FunctionCx<'_, '_, 'tcx>,
 138     local: Local,
 139     layout: TyAndLayout<'tcx>,
 140     is_ssa: bool,
 141 ) -> CPlace<'tcx> {
 142     let place = if is_ssa {
 143         if let rustc_target::abi::Abi::ScalarPair(_, _) = layout.abi {
 144             CPlace::new_var_pair(fx, local, layout)
 145         } else {
 146             CPlace::new_var(fx, local, layout)
 147         }
 148     } else {
 149         CPlace::new_stack_slot(fx, layout)
 150     };
 151
 152     #[cfg(debug_assertions)]
 153     self::comments::add_local_place_comments(fx, place, local);
 154
 155     place
 156 }
 157
 158 pub(crate) fn codegen_fn_prelude<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, start_block: Block) {
 159     fx.bcx.append_block_params_for_function_params(start_block);
 160
 161     fx.bcx.switch_to_block(start_block);
 162     fx.bcx.ins().nop();
 163
 164     let ssa_analyzed = crate::analyze::analyze(fx);
 165
 166     #[cfg(debug_assertions)]
 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     #[cfg(debug_assertions)]
 232     self::comments::add_locals_header_comment(fx);
 233
 234     for (local, arg_kind, ty) in func_params {
 235         let layout = fx.layout_of(ty);
 236
 237         let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 238
 239         // While this is normally an optimization to prevent an unnecessary copy when an argument is
 240         // not mutated by the current function, this is necessary to support unsized arguments.
 241         if let ArgKind::Normal(Some(val)) = arg_kind {
 242             if let Some((addr, meta)) = val.try_to_ptr() {
 243                 let local_decl = &fx.mir.local_decls[local];
 244                 //                       v this ! is important
 245                 let internally_mutable = !val
 246                     .layout()
 247                     .ty
 248                     .is_freeze(fx.tcx.at(local_decl.source_info.span), ParamEnv::reveal_all());
 249                 if local_decl.mutability == mir::Mutability::Not && !internally_mutable {
 250                     // We wont mutate this argument, so it is fine to borrow the backing storage
 251                     // of this argument, to prevent a copy.
 252
 253                     let place = if let Some(meta) = meta {
 254                         CPlace::for_ptr_with_extra(addr, meta, val.layout())
 255                     } else {
 256                         CPlace::for_ptr(addr, val.layout())
 257                     };
 258
 259                     #[cfg(debug_assertions)]
 260                     self::comments::add_local_place_comments(fx, place, local);
 261
 262                     assert_eq!(fx.local_map.push(place), local);
 263                     continue;
 264                 }
 265             }
 266         }
 267
 268         let place = make_local_place(fx, local, layout, is_ssa);
 269         assert_eq!(fx.local_map.push(place), local);
 270
 271         match arg_kind {
 272             ArgKind::Normal(param) => {
 273                 if let Some(param) = param {
 274                     place.write_cvalue(fx, param);
 275                 }
 276             }
 277             ArgKind::Spread(params) => {
 278                 for (i, param) in params.into_iter().enumerate() {
 279                     if let Some(param) = param {
 280                         place.place_field(fx, mir::Field::new(i)).write_cvalue(fx, param);
 281                     }
 282                 }
 283             }
 284         }
 285     }
 286
 287     for local in fx.mir.vars_and_temps_iter() {
 288         let ty = fx.monomorphize(fx.mir.local_decls[local].ty);
 289         let layout = fx.layout_of(ty);
 290
 291         let is_ssa = ssa_analyzed[local] == crate::analyze::SsaKind::Ssa;
 292
 293         let place = make_local_place(fx, local, layout, is_ssa);
 294         assert_eq!(fx.local_map.push(place), local);
 295     }
 296
 297     fx.bcx.ins().jump(*fx.block_map.get(START_BLOCK).unwrap(), &[]);
 298 }
 299
 300 pub(crate) fn codegen_terminator_call<'tcx>(
 301     fx: &mut FunctionCx<'_, '_, 'tcx>,
 302     span: Span,
 303     current_block: Block,
 304     func: &Operand<'tcx>,
 305     args: &[Operand<'tcx>],
 306     destination: Option<(Place<'tcx>, BasicBlock)>,
 307 ) {
 308     let fn_ty = fx.monomorphize(func.ty(fx.mir, fx.tcx));
 309     let fn_sig =
 310         fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), fn_ty.fn_sig(fx.tcx));
 311
 312     let destination = destination.map(|(place, bb)| (codegen_place(fx, place), bb));
 313
 314     // Handle special calls like instrinsics and empty drop glue.
 315     let instance = if let ty::FnDef(def_id, substs) = *fn_ty.kind() {
 316         let instance = ty::Instance::resolve(fx.tcx, ty::ParamEnv::reveal_all(), def_id, substs)
 317             .unwrap()
 318             .unwrap()
 319             .polymorphize(fx.tcx);
 320
 321         if fx.tcx.symbol_name(instance).name.starts_with("llvm.") {
 322             crate::intrinsics::codegen_llvm_intrinsic_call(
 323                 fx,
 324                 &fx.tcx.symbol_name(instance).name,
 325                 substs,
 326                 args,
 327                 destination,
 328             );
 329             return;
 330         }
 331
 332         match instance.def {
 333             InstanceDef::Intrinsic(_) => {
 334                 crate::intrinsics::codegen_intrinsic_call(fx, instance, args, destination, span);
 335                 return;
 336             }
 337             InstanceDef::DropGlue(_, None) => {
 338                 // empty drop glue - a nop.
 339                 let (_, dest) = destination.expect("Non terminating drop_in_place_real???");
 340                 let ret_block = fx.get_block(dest);
 341                 fx.bcx.ins().jump(ret_block, &[]);
 342                 return;
 343             }
 344             _ => Some(instance),
 345         }
 346     } else {
 347         None
 348     };
 349
 350     let extra_args = &args[fn_sig.inputs().len()..];
 351     let extra_args = extra_args
 352         .iter()
 353         .map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx)))
 354         .collect::<Vec<_>>();
 355     let fn_abi = if let Some(instance) = instance {
 356         FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), instance, &extra_args)
 357     } else {
 358         FnAbi::of_fn_ptr(&RevealAllLayoutCx(fx.tcx), fn_ty.fn_sig(fx.tcx), &extra_args)
 359     };
 360
 361     let is_cold = instance
 362         .map(|inst| fx.tcx.codegen_fn_attrs(inst.def_id()).flags.contains(CodegenFnAttrFlags::COLD))
 363         .unwrap_or(false);
 364     if is_cold {
 365         fx.cold_blocks.insert(current_block);
 366     }
 367
 368     // Unpack arguments tuple for closures
 369     let args = if fn_sig.abi == Abi::RustCall {
 370         assert_eq!(args.len(), 2, "rust-call abi requires two arguments");
 371         let self_arg = codegen_operand(fx, &args[0]);
 372         let pack_arg = codegen_operand(fx, &args[1]);
 373
 374         let tupled_arguments = match pack_arg.layout().ty.kind() {
 375             ty::Tuple(ref tupled_arguments) => tupled_arguments,
 376             _ => bug!("argument to function with \"rust-call\" ABI is not a tuple"),
 377         };
 378
 379         let mut args = Vec::with_capacity(1 + tupled_arguments.len());
 380         args.push(self_arg);
 381         for i in 0..tupled_arguments.len() {
 382             args.push(pack_arg.value_field(fx, mir::Field::new(i)));
 383         }
 384         args
 385     } else {
 386         args.iter().map(|arg| codegen_operand(fx, arg)).collect::<Vec<_>>()
 387     };
 388
 389     //   | indirect call target
 390     //   |         | the first argument to be passed
 391     //   v         v
 392     let (func_ref, first_arg) = match instance {
 393         // Trait object call
 394         Some(Instance { def: InstanceDef::Virtual(_, idx), .. }) => {
 395             #[cfg(debug_assertions)]
 396             {
 397                 let nop_inst = fx.bcx.ins().nop();
 398                 fx.add_comment(
 399                     nop_inst,
 400                     format!("virtual call; self arg pass mode: {:?}", &fn_abi.args[0],),
 401                 );
 402             }
 403             let (ptr, method) = crate::vtable::get_ptr_and_method_ref(fx, args[0], idx);
 404             (Some(method), smallvec![ptr])
 405         }
 406
 407         // Normal call
 408         Some(_) => (
 409             None,
 410             args.get(0)
 411                 .map(|arg| adjust_arg_for_abi(fx, *arg, &fn_abi.args[0]))
 412                 .unwrap_or(smallvec![]),
 413         ),
 414
 415         // Indirect call
 416         None => {
 417             #[cfg(debug_assertions)]
 418             {
 419                 let nop_inst = fx.bcx.ins().nop();
 420                 fx.add_comment(nop_inst, "indirect call");
 421             }
 422             let func = codegen_operand(fx, func).load_scalar(fx);
 423             (
 424                 Some(func),
 425                 args.get(0)
 426                     .map(|arg| adjust_arg_for_abi(fx, *arg, &fn_abi.args[0]))
 427                     .unwrap_or(smallvec![]),
 428             )
 429         }
 430     };
 431
 432     let ret_place = destination.map(|(place, _)| place);
 433     let (call_inst, call_args) = self::returning::codegen_with_call_return_arg(
 434         fx,
 435         &fn_abi.ret,
 436         ret_place,
 437         |fx, return_ptr| {
 438             let regular_args_count = args.len();
 439             let mut call_args: Vec<Value> = return_ptr
 440                 .into_iter()
 441                 .chain(first_arg.into_iter())
 442                 .chain(
 443                     args.into_iter()
 444                         .enumerate()
 445                         .skip(1)
 446                         .map(|(i, arg)| adjust_arg_for_abi(fx, arg, &fn_abi.args[i]).into_iter())
 447                         .flatten(),
 448                 )
 449                 .collect::<Vec<_>>();
 450
 451             if instance.map(|inst| inst.def.requires_caller_location(fx.tcx)).unwrap_or(false) {
 452                 // Pass the caller location for `#[track_caller]`.
 453                 let caller_location = fx.get_caller_location(span);
 454                 call_args.extend(
 455                     adjust_arg_for_abi(fx, caller_location, &fn_abi.args[regular_args_count])
 456                         .into_iter(),
 457                 );
 458                 assert_eq!(fn_abi.args.len(), regular_args_count + 1);
 459             } else {
 460                 assert_eq!(fn_abi.args.len(), regular_args_count);
 461             }
 462
 463             let call_inst = if let Some(func_ref) = func_ref {
 464                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
 465                 let sig = fx.bcx.import_signature(sig);
 466                 fx.bcx.ins().call_indirect(sig, func_ref, &call_args)
 467             } else {
 468                 let func_ref =
 469                     fx.get_function_ref(instance.expect("non-indirect call on non-FnDef type"));
 470                 fx.bcx.ins().call(func_ref, &call_args)
 471             };
 472
 473             (call_inst, call_args)
 474         },
 475     );
 476
 477     // FIXME find a cleaner way to support varargs
 478     if fn_sig.c_variadic {
 479         if !matches!(fn_sig.abi, Abi::C { .. }) {
 480             fx.tcx.sess.span_fatal(
 481                 span,
 482                 &format!("Variadic call for non-C abi {:?}", fn_sig.abi),
 483             );
 484         }
 485         let sig_ref = fx.bcx.func.dfg.call_signature(call_inst).unwrap();
 486         let abi_params = call_args
 487             .into_iter()
 488             .map(|arg| {
 489                 let ty = fx.bcx.func.dfg.value_type(arg);
 490                 if !ty.is_int() {
 491                     // FIXME set %al to upperbound on float args once floats are supported
 492                     fx.tcx.sess.span_fatal(span, &format!("Non int ty {:?} for variadic call", ty));
 493                 }
 494                 AbiParam::new(ty)
 495             })
 496             .collect::<Vec<AbiParam>>();
 497         fx.bcx.func.dfg.signatures[sig_ref].params = abi_params;
 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 = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), virtual_drop, &[]);
 532
 533                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
 534                 let sig = fx.bcx.import_signature(sig);
 535                 fx.bcx.ins().call_indirect(sig, drop_fn, &[ptr]);
 536             }
 537             _ => {
 538                 assert!(!matches!(drop_instance.def, InstanceDef::Virtual(_, _)));
 539
 540                 let fn_abi = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), drop_instance, &[]);
 541
 542                 let arg_value = drop_place.place_ref(
 543                     fx,
 544                     fx.layout_of(fx.tcx.mk_ref(
 545                         &ty::RegionKind::ReErased,
 546                         TypeAndMut { ty, mutbl: crate::rustc_hir::Mutability::Mut },
 547                     )),
 548                 );
 549                 let arg_value = adjust_arg_for_abi(fx, arg_value, &fn_abi.args[0]);
 550
 551                 let mut call_args: Vec<Value> = arg_value.into_iter().collect::<Vec<_>>();
 552
 553                 if drop_instance.def.requires_caller_location(fx.tcx) {
 554                     // Pass the caller location for `#[track_caller]`.
 555                     let caller_location = fx.get_caller_location(span);
 556                     call_args.extend(
 557                         adjust_arg_for_abi(fx, caller_location, &fn_abi.args[1]).into_iter(),
 558                     );
 559                 }
 560
 561                 let func_ref = fx.get_function_ref(drop_instance);
 562                 fx.bcx.ins().call(func_ref, &call_args);
 563             }
 564         }
 565     }
 566 }