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<'clif, 'tcx, B: Backend + 'static>(
   7     cx: &mut crate::CodegenCx<'clif, '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: 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                 cleanup: _,
 296                 from_hir_call: _,
 297             } => {
 298                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 299                     fx,
 300                     bb_data.terminator().source_info.span,
 301                     block,
 302                     func,
 303                     args,
 304                     *destination,
 305                 ));
 306             }
 307             TerminatorKind::InlineAsm {
 308                 template,
 309                 operands,
 310                 options: _,
 311                 destination,
 312                 line_spans: _,
 313             } => {
 314                 match template {
 315                     &[] => {
 316                         assert_eq!(operands, &[]);
 317                         match *destination {
 318                             Some(destination) => {
 319                                 let destination_block = fx.get_block(destination);
 320                                 fx.bcx.ins().jump(destination_block, &[]);
 321                             }
 322                             None => bug!(),
 323                         }
 324
 325                         // Black box
 326                     }
 327                     _ => unimpl_fatal!(fx.tcx, bb_data.terminator().source_info.span, "Inline assembly is not supported"),
 328                 }
 329             }
 330             TerminatorKind::Resume | TerminatorKind::Abort => {
 331                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 332             }
 333             TerminatorKind::Unreachable => {
 334                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 335             }
 336             TerminatorKind::Yield { .. }
 337             | TerminatorKind::FalseEdge { .. }
 338             | TerminatorKind::FalseUnwind { .. }
 339             | TerminatorKind::DropAndReplace { .. }
 340             | TerminatorKind::GeneratorDrop => {
 341                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 342             }
 343             TerminatorKind::Drop {
 344                 location,
 345                 target,
 346                 unwind: _,
 347             } => {
 348                 let drop_place = trans_place(fx, *location);
 349                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 350
 351                 let target_block = fx.get_block(*target);
 352                 fx.bcx.ins().jump(target_block, &[]);
 353             }
 354         };
 355     }
 356
 357     fx.bcx.seal_all_blocks();
 358     fx.bcx.finalize();
 359 }
 360
 361 fn trans_stmt<'tcx>(
 362     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 363     #[allow(unused_variables)]
 364     cur_block: Block,
 365     stmt: &Statement<'tcx>,
 366 ) {
 367     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 368
 369     fx.set_debug_loc(stmt.source_info);
 370
 371     #[cfg(false_debug_assertions)]
 372     match &stmt.kind {
 373         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 374         _ => {
 375             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 376             fx.add_comment(inst, format!("{:?}", stmt));
 377         }
 378     }
 379
 380     match &stmt.kind {
 381         StatementKind::SetDiscriminant {
 382             place,
 383             variant_index,
 384         } => {
 385             let place = trans_place(fx, **place);
 386             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 387         }
 388         StatementKind::Assign(to_place_and_rval) => {
 389             let lval = trans_place(fx, to_place_and_rval.0);
 390             let dest_layout = lval.layout();
 391             match &to_place_and_rval.1 {
 392                 Rvalue::Use(operand) => {
 393                     let val = trans_operand(fx, operand);
 394                     lval.write_cvalue(fx, val);
 395                 }
 396                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 397                     let place = trans_place(fx, *place);
 398                     place.write_place_ref(fx, lval);
 399                 }
 400                 Rvalue::ThreadLocalRef(def_id) => {
 401                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 402                     lval.write_cvalue(fx, val);
 403                 }
 404                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 405                     let lhs = trans_operand(fx, lhs);
 406                     let rhs = trans_operand(fx, rhs);
 407
 408                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 409                     lval.write_cvalue(fx, res);
 410                 }
 411                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 412                     let lhs = trans_operand(fx, lhs);
 413                     let rhs = trans_operand(fx, rhs);
 414
 415                     let res = if !fx.tcx.sess.overflow_checks() {
 416                         let val =
 417                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 418                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 419                         CValue::by_val_pair(val, is_overflow, lval.layout())
 420                     } else {
 421                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 422                     };
 423
 424                     lval.write_cvalue(fx, res);
 425                 }
 426                 Rvalue::UnaryOp(un_op, operand) => {
 427                     let operand = trans_operand(fx, operand);
 428                     let layout = operand.layout();
 429                     let val = operand.load_scalar(fx);
 430                     let res = match un_op {
 431                         UnOp::Not => {
 432                             match layout.ty.kind {
 433                                 ty::Bool => {
 434                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 435                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 436                                 }
 437                                 ty::Uint(_) | ty::Int(_) => {
 438                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 439                                 }
 440                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 441                             }
 442                         }
 443                         UnOp::Neg => match layout.ty.kind {
 444                             ty::Int(IntTy::I128) => {
 445                                 // FIXME remove this case once ineg.i128 works
 446                                 let zero = CValue::const_val(fx, layout, 0);
 447                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 448                             }
 449                             ty::Int(_) => {
 450                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 451                             }
 452                             ty::Float(_) => {
 453                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 454                             }
 455                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 456                         },
 457                     };
 458                     lval.write_cvalue(fx, res);
 459                 }
 460                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 461                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 462                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 463                     match from_ty.kind {
 464                         ty::FnDef(def_id, substs) => {
 465                             let func_ref = fx.get_function_ref(
 466                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 467                                     .unwrap(),
 468                             );
 469                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 470                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 471                         }
 472                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 473                     }
 474                 }
 475                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 476                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 477                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 478                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 479                     let operand = trans_operand(fx, operand);
 480                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 481                 }
 482                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 483                     let operand = trans_operand(fx, operand);
 484                     let from_ty = operand.layout().ty;
 485                     let to_ty = fx.monomorphize(to_ty);
 486
 487                     fn is_fat_ptr<'tcx>(
 488                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 489                         ty: Ty<'tcx>,
 490                     ) -> bool {
 491                         ty.builtin_deref(true)
 492                             .map(
 493                                 |ty::TypeAndMut {
 494                                      ty: pointee_ty,
 495                                      mutbl: _,
 496                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 497                             )
 498                             .unwrap_or(false)
 499                     }
 500
 501                     if is_fat_ptr(fx, from_ty) {
 502                         if is_fat_ptr(fx, to_ty) {
 503                             // fat-ptr -> fat-ptr
 504                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 505                         } else {
 506                             // fat-ptr -> thin-ptr
 507                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 508                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 509                         }
 510                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 511                         // enum -> discriminant value
 512                         assert!(adt_def.is_enum());
 513                         match to_ty.kind {
 514                             ty::Uint(_) | ty::Int(_) => {}
 515                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 516                         }
 517
 518                         let discr = crate::discriminant::codegen_get_discriminant(
 519                             fx,
 520                             operand,
 521                             fx.layout_of(to_ty),
 522                         );
 523                         lval.write_cvalue(fx, discr);
 524                     } else {
 525                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 526                         let from = operand.load_scalar(fx);
 527
 528                         let res = clif_int_or_float_cast(
 529                             fx,
 530                             from,
 531                             type_sign(from_ty),
 532                             to_clif_ty,
 533                             type_sign(to_ty),
 534                         );
 535                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 536                     }
 537                 }
 538                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 539                     let operand = trans_operand(fx, operand);
 540                     match operand.layout().ty.kind {
 541                         ty::Closure(def_id, substs) => {
 542                             let instance = Instance::resolve_closure(
 543                                 fx.tcx,
 544                                 def_id,
 545                                 substs,
 546                                 ty::ClosureKind::FnOnce,
 547                             );
 548                             let func_ref = fx.get_function_ref(instance);
 549                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 550                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 551                         }
 552                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 553                     }
 554                 }
 555                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 556                     let operand = trans_operand(fx, operand);
 557                     operand.unsize_value(fx, lval);
 558                 }
 559                 Rvalue::Discriminant(place) => {
 560                     let place = trans_place(fx, *place);
 561                     let value = place.to_cvalue(fx);
 562                     let discr =
 563                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 564                     lval.write_cvalue(fx, discr);
 565                 }
 566                 Rvalue::Repeat(operand, times) => {
 567                     let operand = trans_operand(fx, operand);
 568                     let times = fx
 569                         .monomorphize(times)
 570                         .eval(fx.tcx, ParamEnv::reveal_all())
 571                         .val
 572                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 573                         .unwrap();
 574                     for i in 0..times {
 575                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 576                         let to = lval.place_index(fx, index);
 577                         to.write_cvalue(fx, operand);
 578                     }
 579                 }
 580                 Rvalue::Len(place) => {
 581                     let place = trans_place(fx, *place);
 582                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 583                     let len = codegen_array_len(fx, place);
 584                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 585                 }
 586                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 587                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 588
 589                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 590                     let content_ty = fx.monomorphize(content_ty);
 591                     let layout = fx.layout_of(content_ty);
 592                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 593                     let llalign = fx
 594                         .bcx
 595                         .ins()
 596                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 597                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 598
 599                     // Allocate space:
 600                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 601                         Ok(id) => id,
 602                         Err(s) => {
 603                             fx.tcx
 604                                 .sess
 605                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 606                         }
 607                     };
 608                     let instance = ty::Instance::mono(fx.tcx, def_id);
 609                     let func_ref = fx.get_function_ref(instance);
 610                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 611                     let ptr = fx.bcx.inst_results(call)[0];
 612                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 613                 }
 614                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 615                     assert!(lval
 616                         .layout()
 617                         .ty
 618                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 619                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 620                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 621                     lval.write_cvalue(fx, val);
 622                 }
 623                 Rvalue::Aggregate(kind, operands) => match **kind {
 624                     AggregateKind::Array(_ty) => {
 625                         for (i, operand) in operands.into_iter().enumerate() {
 626                             let operand = trans_operand(fx, operand);
 627                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 628                             let to = lval.place_index(fx, index);
 629                             to.write_cvalue(fx, operand);
 630                         }
 631                     }
 632                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 633                 },
 634             }
 635         }
 636         StatementKind::StorageLive(_)
 637         | StatementKind::StorageDead(_)
 638         | StatementKind::Nop
 639         | StatementKind::FakeRead(..)
 640         | StatementKind::Retag { .. }
 641         | StatementKind::AscribeUserType(..) => {}
 642
 643         StatementKind::LlvmInlineAsm(asm) => {
 644             use rustc_span::symbol::Symbol;
 645             let LlvmInlineAsm {
 646                 asm,
 647                 outputs: _,
 648                 inputs: _,
 649             } = &**asm;
 650             let rustc_hir::LlvmInlineAsmInner {
 651                 asm: asm_code, // Name
 652                 outputs,       // Vec<Name>
 653                 inputs,        // Vec<Name>
 654                 clobbers,      // Vec<Name>
 655                 volatile,      // bool
 656                 alignstack,    // bool
 657                 dialect: _,    // rustc_ast::ast::AsmDialect
 658                 asm_str_style: _,
 659             } = asm;
 660             match &*asm_code.as_str() {
 661                 cpuid if cpuid.contains("cpuid") => {
 662                     crate::trap::trap_unimplemented(
 663                         fx,
 664                         "__cpuid_count arch intrinsic is not supported",
 665                     );
 666                 }
 667                 "xgetbv" => {
 668                     assert_eq!(inputs, &[Symbol::intern("{ecx}")]);
 669
 670                     assert_eq!(outputs.len(), 2);
 671                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 672                         assert_eq!(&outputs[i].constraint.as_str(), c);
 673                         assert!(!outputs[i].is_rw);
 674                         assert!(!outputs[i].is_indirect);
 675                     }
 676
 677                     assert_eq!(clobbers, &[]);
 678
 679                     assert!(!volatile);
 680                     assert!(!alignstack);
 681
 682                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 683                 }
 684                 _ => unimpl_fatal!(fx.tcx, stmt.source_info.span, "Inline assembly is not supported"),
 685             }
 686         }
 687     }
 688 }
 689
 690 fn codegen_array_len<'tcx>(
 691     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 692     place: CPlace<'tcx>,
 693 ) -> Value {
 694     match place.layout().ty.kind {
 695         ty::Array(_elem_ty, len) => {
 696             let len = fx.monomorphize(&len)
 697                 .eval(fx.tcx, ParamEnv::reveal_all())
 698                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 699             fx.bcx.ins().iconst(fx.pointer_type, len)
 700         }
 701         ty::Slice(_elem_ty) => place
 702             .to_ptr_maybe_unsized()
 703             .1
 704             .expect("Length metadata for slice place"),
 705         _ => bug!("Rvalue::Len({:?})", place),
 706     }
 707 }
 708
 709 pub(crate) fn trans_place<'tcx>(
 710     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 711     place: Place<'tcx>,
 712 ) -> CPlace<'tcx> {
 713     let mut cplace = fx.get_local_place(place.local);
 714
 715     for elem in place.projection {
 716         match elem {
 717             PlaceElem::Deref => {
 718                 cplace = cplace.place_deref(fx);
 719             }
 720             PlaceElem::Field(field, _ty) => {
 721                 cplace = cplace.place_field(fx, field);
 722             }
 723             PlaceElem::Index(local) => {
 724                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 725                 cplace = cplace.place_index(fx, index);
 726             }
 727             PlaceElem::ConstantIndex {
 728                 offset,
 729                 min_length: _,
 730                 from_end,
 731             } => {
 732                 let index = if !from_end {
 733                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 734                 } else {
 735                     let len = codegen_array_len(fx, cplace);
 736                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 737                 };
 738                 cplace = cplace.place_index(fx, index);
 739             }
 740             PlaceElem::Subslice { from, to, from_end } => {
 741                 // These indices are generated by slice patterns.
 742                 // slice[from:-to] in Python terms.
 743
 744                 match cplace.layout().ty.kind {
 745                     ty::Array(elem_ty, _len) => {
 746                         assert!(!from_end, "array subslices are never `from_end`");
 747                         let elem_layout = fx.layout_of(elem_ty);
 748                         let ptr = cplace.to_ptr();
 749                         cplace = CPlace::for_ptr(
 750                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 751                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 752                         );
 753                     }
 754                     ty::Slice(elem_ty) => {
 755                         assert!(from_end, "slice subslices should be `from_end`");
 756                         let elem_layout = fx.layout_of(elem_ty);
 757                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 758                         let len = len.unwrap();
 759                         cplace = CPlace::for_ptr_with_extra(
 760                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 761                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 762                             cplace.layout(),
 763                         );
 764                     }
 765                     _ => unreachable!(),
 766                 }
 767             }
 768             PlaceElem::Downcast(_adt_def, variant) => {
 769                 cplace = cplace.downcast_variant(fx, variant);
 770             }
 771         }
 772     }
 773
 774     cplace
 775 }
 776
 777 pub(crate) fn trans_operand<'tcx>(
 778     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 779     operand: &Operand<'tcx>,
 780 ) -> CValue<'tcx> {
 781     match operand {
 782         Operand::Move(place) | Operand::Copy(place) => {
 783             let cplace = trans_place(fx, *place);
 784             cplace.to_cvalue(fx)
 785         }
 786         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 787     }
 788 }