src/base.rs

   1 use rustc_middle::ty::adjustment::PointerCast;
   2 use rustc_index::vec::IndexVec;
   3
   4 use crate::prelude::*;
   5
   6 pub(crate) fn trans_fn<'tcx, B: Backend + 'static>(
   7     cx: &mut crate::CodegenCx<'tcx, B>,
   8     instance: Instance<'tcx>,
   9     linkage: Linkage,
  10 ) {
  11     let tcx = cx.tcx;
  12
  13     let mir = tcx.instance_mir(instance.def);
  14
  15     // Declare function
  16     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  17     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  18     let mut debug_context = cx
  19         .debug_context
  20         .as_mut()
  21         .map(|debug_context| FunctionDebugContext::new(debug_context, instance, func_id, &name));
  22
  23     // Make FunctionBuilder
  24     let context = &mut cx.cached_context;
  25     context.clear();
  26     context.func.name = ExternalName::user(0, func_id.as_u32());
  27     context.func.signature = sig;
  28     context.func.collect_debug_info();
  29     let mut func_ctx = FunctionBuilderContext::new();
  30     let mut bcx = FunctionBuilder::new(&mut context.func, &mut func_ctx);
  31
  32     // Predefine blocks
  33     let start_block = bcx.create_block();
  34     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  35
  36     // Make FunctionCx
  37     let pointer_type = cx.module.target_config().pointer_type();
  38     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  39
  40     let mut fx = FunctionCx {
  41         tcx,
  42         module: &mut cx.module,
  43         pointer_type,
  44
  45         instance,
  46         mir,
  47
  48         bcx,
  49         block_map,
  50         local_map: FxHashMap::with_capacity_and_hasher(mir.local_decls.len(), Default::default()),
  51         caller_location: None, // set by `codegen_fn_prelude`
  52         cold_blocks: EntitySet::new(),
  53
  54         clif_comments,
  55         constants_cx: &mut cx.constants_cx,
  56         vtables: &mut cx.vtables,
  57         source_info_set: indexmap::IndexSet::new(),
  58     };
  59
  60     let arg_uninhabited = fx.mir.args_iter().any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  61
  62     if arg_uninhabited {
  63         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  64         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  65         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  66     } else {
  67         tcx.sess.time("codegen clif ir", || {
  68             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, true));
  69             codegen_fn_content(&mut fx);
  70         });
  71     }
  72
  73     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  74     let instance = fx.instance;
  75     let mut clif_comments = fx.clif_comments;
  76     let source_info_set = fx.source_info_set;
  77     let local_map = fx.local_map;
  78     let cold_blocks = fx.cold_blocks;
  79
  80     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
  81
  82     // Verify function
  83     verify_func(tcx, &clif_comments, &context.func);
  84
  85     // Perform rust specific optimizations
  86     tcx.sess.time("optimize clif ir", || {
  87         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
  88     });
  89
  90     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
  91     // instruction, which doesn't have an encoding.
  92     context.compute_cfg();
  93     context.compute_domtree();
  94     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
  95
  96     // Define function
  97     let module = &mut cx.module;
  98     tcx.sess.time(
  99         "define function",
 100         || module.define_function(
 101             func_id,
 102             context,
 103             &mut cranelift_codegen::binemit::NullTrapSink {},
 104         ).unwrap(),
 105     );
 106
 107     // Write optimized function to file for debugging
 108     {
 109         let value_ranges = context
 110             .build_value_labels_ranges(cx.module.isa())
 111             .expect("value location ranges");
 112
 113         crate::pretty_clif::write_clif_file(
 114             cx.tcx,
 115             "opt",
 116             instance,
 117             &context.func,
 118             &clif_comments,
 119             Some(&value_ranges),
 120         );
 121     }
 122
 123     // Define debuginfo for function
 124     let isa = cx.module.isa();
 125     let unwind_context = &mut cx.unwind_context;
 126     tcx.sess.time("generate debug info", || {
 127         debug_context
 128             .as_mut()
 129             .map(|x| x.define(context, isa, &source_info_set, local_map));
 130         unwind_context.add_function(func_id, &context, isa);
 131     });
 132
 133     // Clear context to make it usable for the next function
 134     context.clear();
 135 }
 136
 137 pub(crate) fn verify_func(tcx: TyCtxt<'_>, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 138     tcx.sess.time("verify clif ir", || {
 139         let flags = settings::Flags::new(settings::builder());
 140         match ::cranelift_codegen::verify_function(&func, &flags) {
 141             Ok(_) => {}
 142             Err(err) => {
 143                 tcx.sess.err(&format!("{:?}", err));
 144                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 145                     &func,
 146                     None,
 147                     Some(Box::new(writer)),
 148                     err,
 149                 );
 150                 tcx.sess
 151                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 152             }
 153         }
 154     });
 155 }
 156
 157 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 158     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 159         let block = fx.get_block(bb);
 160         fx.bcx.switch_to_block(block);
 161
 162         if bb_data.is_cleanup {
 163             // Unwinding after panicking is not supported
 164             continue;
 165
 166             // FIXME once unwinding is supported uncomment next lines
 167             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 168             // fx.cold_blocks.insert(block);
 169         }
 170
 171         fx.bcx.ins().nop();
 172         for stmt in &bb_data.statements {
 173             fx.set_debug_loc(stmt.source_info);
 174             trans_stmt(fx, block, stmt);
 175         }
 176
 177         #[cfg(debug_assertions)]
 178         {
 179             let mut terminator_head = "\n".to_string();
 180             bb_data
 181                 .terminator()
 182                 .kind
 183                 .fmt_head(&mut terminator_head)
 184                 .unwrap();
 185             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 186             fx.add_comment(inst, terminator_head);
 187         }
 188
 189         fx.set_debug_loc(bb_data.terminator().source_info);
 190
 191         match &bb_data.terminator().kind {
 192             TerminatorKind::Goto { target } => {
 193                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 194                     let mut can_immediately_return = true;
 195                     for stmt in &fx.mir[*target].statements {
 196                         if let StatementKind::StorageDead(_) = stmt.kind {
 197                         } else {
 198                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 199                             can_immediately_return = false;
 200                             break;
 201                         }
 202                     }
 203
 204                     if can_immediately_return {
 205                         crate::abi::codegen_return(fx);
 206                         continue;
 207                     }
 208                 }
 209
 210                 let block = fx.get_block(*target);
 211                 fx.bcx.ins().jump(block, &[]);
 212             }
 213             TerminatorKind::Return => {
 214                 crate::abi::codegen_return(fx);
 215             }
 216             TerminatorKind::Assert {
 217                 cond,
 218                 expected,
 219                 msg,
 220                 target,
 221                 cleanup: _,
 222             } => {
 223                 if !fx.tcx.sess.overflow_checks() {
 224                     if let mir::AssertKind::OverflowNeg = *msg {
 225                         let target = fx.get_block(*target);
 226                         fx.bcx.ins().jump(target, &[]);
 227                         continue;
 228                     }
 229                 }
 230                 let cond = trans_operand(fx, cond).load_scalar(fx);
 231
 232                 let target = fx.get_block(*target);
 233                 let failure = fx.bcx.create_block();
 234                 fx.cold_blocks.insert(failure);
 235
 236                 if *expected {
 237                     fx.bcx.ins().brz(cond, failure, &[]);
 238                 } else {
 239                     fx.bcx.ins().brnz(cond, failure, &[]);
 240                 };
 241                 fx.bcx.ins().jump(target, &[]);
 242
 243                 fx.bcx.switch_to_block(failure);
 244
 245                 let location = fx.get_caller_location(bb_data.terminator().source_info.span).load_scalar(fx);
 246
 247                 let args;
 248                 let lang_item = match msg {
 249                     AssertKind::BoundsCheck { ref len, ref index } => {
 250                         let len = trans_operand(fx, len).load_scalar(fx);
 251                         let index = trans_operand(fx, index).load_scalar(fx);
 252                         args = [index, len, location];
 253                         rustc_hir::lang_items::PanicBoundsCheckFnLangItem
 254                     }
 255                     _ => {
 256                         let msg_str = msg.description();
 257                         let msg_ptr = fx.anonymous_str("assert", msg_str);
 258                         let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 259                         args = [msg_ptr, msg_len, location];
 260                         rustc_hir::lang_items::PanicFnLangItem
 261                     }
 262                 };
 263
 264                 let def_id = fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| {
 265                     fx.tcx.sess.span_fatal(bb_data.terminator().source_info.span, &s)
 266                 });
 267
 268                 let instance = Instance::mono(fx.tcx, def_id);
 269                 let symbol_name = fx.tcx.symbol_name(instance).name.as_str();
 270
 271                 fx.lib_call(&*symbol_name, vec![fx.pointer_type, fx.pointer_type, fx.pointer_type], vec![], &args);
 272
 273                 crate::trap::trap_unreachable(fx, "panic lang item returned");
 274             }
 275
 276             TerminatorKind::SwitchInt {
 277                 discr,
 278                 switch_ty: _,
 279                 values,
 280                 targets,
 281             } => {
 282                 let discr = trans_operand(fx, discr).load_scalar(fx);
 283                 let mut switch = ::cranelift_frontend::Switch::new();
 284                 for (i, value) in values.iter().enumerate() {
 285                     let block = fx.get_block(targets[i]);
 286                     switch.set_entry(*value as u64, block);
 287                 }
 288                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 289                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 290             }
 291             TerminatorKind::Call {
 292                 func,
 293                 args,
 294                 destination,
 295                 fn_span,
 296                 cleanup: _,
 297                 from_hir_call: _,
 298             } => {
 299                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 300                     fx,
 301                     *fn_span,
 302                     block,
 303                     func,
 304                     args,
 305                     *destination,
 306                 ));
 307             }
 308             TerminatorKind::InlineAsm {
 309                 template,
 310                 operands,
 311                 options: _,
 312                 destination,
 313                 line_spans: _,
 314             } => {
 315                 match template {
 316                     &[] => {
 317                         assert_eq!(operands, &[]);
 318                         match *destination {
 319                             Some(destination) => {
 320                                 let destination_block = fx.get_block(destination);
 321                                 fx.bcx.ins().jump(destination_block, &[]);
 322                             }
 323                             None => bug!(),
 324                         }
 325
 326                         // Black box
 327                     }
 328                     _ => unimpl_fatal!(fx.tcx, bb_data.terminator().source_info.span, "Inline assembly is not supported"),
 329                 }
 330             }
 331             TerminatorKind::Resume | TerminatorKind::Abort => {
 332                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 333             }
 334             TerminatorKind::Unreachable => {
 335                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 336             }
 337             TerminatorKind::Yield { .. }
 338             | TerminatorKind::FalseEdge { .. }
 339             | TerminatorKind::FalseUnwind { .. }
 340             | TerminatorKind::DropAndReplace { .. }
 341             | TerminatorKind::GeneratorDrop => {
 342                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 343             }
 344             TerminatorKind::Drop {
 345                 location,
 346                 target,
 347                 unwind: _,
 348             } => {
 349                 let drop_place = trans_place(fx, *location);
 350                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 351
 352                 let target_block = fx.get_block(*target);
 353                 fx.bcx.ins().jump(target_block, &[]);
 354             }
 355         };
 356     }
 357
 358     fx.bcx.seal_all_blocks();
 359     fx.bcx.finalize();
 360 }
 361
 362 fn trans_stmt<'tcx>(
 363     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 364     #[allow(unused_variables)]
 365     cur_block: Block,
 366     stmt: &Statement<'tcx>,
 367 ) {
 368     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 369
 370     fx.set_debug_loc(stmt.source_info);
 371
 372     #[cfg(false_debug_assertions)]
 373     match &stmt.kind {
 374         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 375         _ => {
 376             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 377             fx.add_comment(inst, format!("{:?}", stmt));
 378         }
 379     }
 380
 381     match &stmt.kind {
 382         StatementKind::SetDiscriminant {
 383             place,
 384             variant_index,
 385         } => {
 386             let place = trans_place(fx, **place);
 387             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 388         }
 389         StatementKind::Assign(to_place_and_rval) => {
 390             let lval = trans_place(fx, to_place_and_rval.0);
 391             let dest_layout = lval.layout();
 392             match &to_place_and_rval.1 {
 393                 Rvalue::Use(operand) => {
 394                     let val = trans_operand(fx, operand);
 395                     lval.write_cvalue(fx, val);
 396                 }
 397                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 398                     let place = trans_place(fx, *place);
 399                     place.write_place_ref(fx, lval);
 400                 }
 401                 Rvalue::ThreadLocalRef(def_id) => {
 402                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 403                     lval.write_cvalue(fx, val);
 404                 }
 405                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 406                     let lhs = trans_operand(fx, lhs);
 407                     let rhs = trans_operand(fx, rhs);
 408
 409                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 410                     lval.write_cvalue(fx, res);
 411                 }
 412                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 413                     let lhs = trans_operand(fx, lhs);
 414                     let rhs = trans_operand(fx, rhs);
 415
 416                     let res = if !fx.tcx.sess.overflow_checks() {
 417                         let val =
 418                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 419                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 420                         CValue::by_val_pair(val, is_overflow, lval.layout())
 421                     } else {
 422                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 423                     };
 424
 425                     lval.write_cvalue(fx, res);
 426                 }
 427                 Rvalue::UnaryOp(un_op, operand) => {
 428                     let operand = trans_operand(fx, operand);
 429                     let layout = operand.layout();
 430                     let val = operand.load_scalar(fx);
 431                     let res = match un_op {
 432                         UnOp::Not => {
 433                             match layout.ty.kind {
 434                                 ty::Bool => {
 435                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 436                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 437                                 }
 438                                 ty::Uint(_) | ty::Int(_) => {
 439                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 440                                 }
 441                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 442                             }
 443                         }
 444                         UnOp::Neg => match layout.ty.kind {
 445                             ty::Int(IntTy::I128) => {
 446                                 // FIXME remove this case once ineg.i128 works
 447                                 let zero = CValue::const_val(fx, layout, 0);
 448                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 449                             }
 450                             ty::Int(_) => {
 451                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 452                             }
 453                             ty::Float(_) => {
 454                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 455                             }
 456                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 457                         },
 458                     };
 459                     lval.write_cvalue(fx, res);
 460                 }
 461                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 462                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 463                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 464                     match from_ty.kind {
 465                         ty::FnDef(def_id, substs) => {
 466                             let func_ref = fx.get_function_ref(
 467                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 468                                     .unwrap(),
 469                             );
 470                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 471                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 472                         }
 473                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 474                     }
 475                 }
 476                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 477                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 478                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 479                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 480                     let operand = trans_operand(fx, operand);
 481                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 482                 }
 483                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 484                     let operand = trans_operand(fx, operand);
 485                     let from_ty = operand.layout().ty;
 486                     let to_ty = fx.monomorphize(to_ty);
 487
 488                     fn is_fat_ptr<'tcx>(
 489                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 490                         ty: Ty<'tcx>,
 491                     ) -> bool {
 492                         ty.builtin_deref(true)
 493                             .map(
 494                                 |ty::TypeAndMut {
 495                                      ty: pointee_ty,
 496                                      mutbl: _,
 497                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 498                             )
 499                             .unwrap_or(false)
 500                     }
 501
 502                     if is_fat_ptr(fx, from_ty) {
 503                         if is_fat_ptr(fx, to_ty) {
 504                             // fat-ptr -> fat-ptr
 505                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 506                         } else {
 507                             // fat-ptr -> thin-ptr
 508                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 509                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 510                         }
 511                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 512                         // enum -> discriminant value
 513                         assert!(adt_def.is_enum());
 514                         match to_ty.kind {
 515                             ty::Uint(_) | ty::Int(_) => {}
 516                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 517                         }
 518
 519                         let discr = crate::discriminant::codegen_get_discriminant(
 520                             fx,
 521                             operand,
 522                             fx.layout_of(to_ty),
 523                         );
 524                         lval.write_cvalue(fx, discr);
 525                     } else {
 526                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 527                         let from = operand.load_scalar(fx);
 528
 529                         let res = clif_int_or_float_cast(
 530                             fx,
 531                             from,
 532                             type_sign(from_ty),
 533                             to_clif_ty,
 534                             type_sign(to_ty),
 535                         );
 536                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 537                     }
 538                 }
 539                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 540                     let operand = trans_operand(fx, operand);
 541                     match operand.layout().ty.kind {
 542                         ty::Closure(def_id, substs) => {
 543                             let instance = Instance::resolve_closure(
 544                                 fx.tcx,
 545                                 def_id,
 546                                 substs,
 547                                 ty::ClosureKind::FnOnce,
 548                             );
 549                             let func_ref = fx.get_function_ref(instance);
 550                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 551                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 552                         }
 553                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 554                     }
 555                 }
 556                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 557                     let operand = trans_operand(fx, operand);
 558                     operand.unsize_value(fx, lval);
 559                 }
 560                 Rvalue::Discriminant(place) => {
 561                     let place = trans_place(fx, *place);
 562                     let value = place.to_cvalue(fx);
 563                     let discr =
 564                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 565                     lval.write_cvalue(fx, discr);
 566                 }
 567                 Rvalue::Repeat(operand, times) => {
 568                     let operand = trans_operand(fx, operand);
 569                     let times = fx
 570                         .monomorphize(times)
 571                         .eval(fx.tcx, ParamEnv::reveal_all())
 572                         .val
 573                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 574                         .unwrap();
 575                     for i in 0..times {
 576                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 577                         let to = lval.place_index(fx, index);
 578                         to.write_cvalue(fx, operand);
 579                     }
 580                 }
 581                 Rvalue::Len(place) => {
 582                     let place = trans_place(fx, *place);
 583                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 584                     let len = codegen_array_len(fx, place);
 585                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 586                 }
 587                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 588                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 589
 590                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 591                     let content_ty = fx.monomorphize(content_ty);
 592                     let layout = fx.layout_of(content_ty);
 593                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 594                     let llalign = fx
 595                         .bcx
 596                         .ins()
 597                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 598                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 599
 600                     // Allocate space:
 601                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 602                         Ok(id) => id,
 603                         Err(s) => {
 604                             fx.tcx
 605                                 .sess
 606                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 607                         }
 608                     };
 609                     let instance = ty::Instance::mono(fx.tcx, def_id);
 610                     let func_ref = fx.get_function_ref(instance);
 611                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 612                     let ptr = fx.bcx.inst_results(call)[0];
 613                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 614                 }
 615                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 616                     assert!(lval
 617                         .layout()
 618                         .ty
 619                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 620                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 621                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 622                     lval.write_cvalue(fx, val);
 623                 }
 624                 Rvalue::Aggregate(kind, operands) => match **kind {
 625                     AggregateKind::Array(_ty) => {
 626                         for (i, operand) in operands.into_iter().enumerate() {
 627                             let operand = trans_operand(fx, operand);
 628                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 629                             let to = lval.place_index(fx, index);
 630                             to.write_cvalue(fx, operand);
 631                         }
 632                     }
 633                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 634                 },
 635             }
 636         }
 637         StatementKind::StorageLive(_)
 638         | StatementKind::StorageDead(_)
 639         | StatementKind::Nop
 640         | StatementKind::FakeRead(..)
 641         | StatementKind::Retag { .. }
 642         | StatementKind::AscribeUserType(..) => {}
 643
 644         StatementKind::LlvmInlineAsm(asm) => {
 645             use rustc_span::symbol::Symbol;
 646             let LlvmInlineAsm {
 647                 asm,
 648                 outputs: _,
 649                 inputs: _,
 650             } = &**asm;
 651             let rustc_hir::LlvmInlineAsmInner {
 652                 asm: asm_code, // Name
 653                 outputs,       // Vec<Name>
 654                 inputs,        // Vec<Name>
 655                 clobbers,      // Vec<Name>
 656                 volatile,      // bool
 657                 alignstack,    // bool
 658                 dialect: _,    // rustc_ast::ast::AsmDialect
 659                 asm_str_style: _,
 660             } = asm;
 661             match &*asm_code.as_str() {
 662                 cpuid if cpuid.contains("cpuid") => {
 663                     crate::trap::trap_unimplemented(
 664                         fx,
 665                         "__cpuid_count arch intrinsic is not supported",
 666                     );
 667                 }
 668                 "xgetbv" => {
 669                     assert_eq!(inputs, &[Symbol::intern("{ecx}")]);
 670
 671                     assert_eq!(outputs.len(), 2);
 672                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 673                         assert_eq!(&outputs[i].constraint.as_str(), c);
 674                         assert!(!outputs[i].is_rw);
 675                         assert!(!outputs[i].is_indirect);
 676                     }
 677
 678                     assert_eq!(clobbers, &[]);
 679
 680                     assert!(!volatile);
 681                     assert!(!alignstack);
 682
 683                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 684                 }
 685                 _ => unimpl_fatal!(fx.tcx, stmt.source_info.span, "Inline assembly is not supported"),
 686             }
 687         }
 688     }
 689 }
 690
 691 fn codegen_array_len<'tcx>(
 692     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 693     place: CPlace<'tcx>,
 694 ) -> Value {
 695     match place.layout().ty.kind {
 696         ty::Array(_elem_ty, len) => {
 697             let len = fx.monomorphize(&len)
 698                 .eval(fx.tcx, ParamEnv::reveal_all())
 699                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 700             fx.bcx.ins().iconst(fx.pointer_type, len)
 701         }
 702         ty::Slice(_elem_ty) => place
 703             .to_ptr_maybe_unsized()
 704             .1
 705             .expect("Length metadata for slice place"),
 706         _ => bug!("Rvalue::Len({:?})", place),
 707     }
 708 }
 709
 710 pub(crate) fn trans_place<'tcx>(
 711     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 712     place: Place<'tcx>,
 713 ) -> CPlace<'tcx> {
 714     let mut cplace = fx.get_local_place(place.local);
 715
 716     for elem in place.projection {
 717         match elem {
 718             PlaceElem::Deref => {
 719                 cplace = cplace.place_deref(fx);
 720             }
 721             PlaceElem::Field(field, _ty) => {
 722                 cplace = cplace.place_field(fx, field);
 723             }
 724             PlaceElem::Index(local) => {
 725                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 726                 cplace = cplace.place_index(fx, index);
 727             }
 728             PlaceElem::ConstantIndex {
 729                 offset,
 730                 min_length: _,
 731                 from_end,
 732             } => {
 733                 let index = if !from_end {
 734                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 735                 } else {
 736                     let len = codegen_array_len(fx, cplace);
 737                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 738                 };
 739                 cplace = cplace.place_index(fx, index);
 740             }
 741             PlaceElem::Subslice { from, to, from_end } => {
 742                 // These indices are generated by slice patterns.
 743                 // slice[from:-to] in Python terms.
 744
 745                 match cplace.layout().ty.kind {
 746                     ty::Array(elem_ty, _len) => {
 747                         assert!(!from_end, "array subslices are never `from_end`");
 748                         let elem_layout = fx.layout_of(elem_ty);
 749                         let ptr = cplace.to_ptr();
 750                         cplace = CPlace::for_ptr(
 751                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 752                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 753                         );
 754                     }
 755                     ty::Slice(elem_ty) => {
 756                         assert!(from_end, "slice subslices should be `from_end`");
 757                         let elem_layout = fx.layout_of(elem_ty);
 758                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 759                         let len = len.unwrap();
 760                         cplace = CPlace::for_ptr_with_extra(
 761                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 762                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 763                             cplace.layout(),
 764                         );
 765                     }
 766                     _ => unreachable!(),
 767                 }
 768             }
 769             PlaceElem::Downcast(_adt_def, variant) => {
 770                 cplace = cplace.downcast_variant(fx, variant);
 771             }
 772         }
 773     }
 774
 775     cplace
 776 }
 777
 778 pub(crate) fn trans_operand<'tcx>(
 779     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 780     operand: &Operand<'tcx>,
 781 ) -> CValue<'tcx> {
 782     match operand {
 783         Operand::Move(place) | Operand::Copy(place) => {
 784             let cplace = trans_place(fx, *place);
 785             cplace.to_cvalue(fx)
 786         }
 787         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 788     }
 789 }