src/base.rs

   1 use rustc::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 block's
  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: HashMap::new(),
  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     let is_call_once_for_box = name.starts_with("_ZN83_$LT$alloc..boxed..Box$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once");
  62
  63     if arg_uninhabited {
  64         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  65         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  66         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  67     } else if is_call_once_for_box {
  68         // HACK implement `<Box<F> as FnOnce>::call_once` without `alloca`.
  69         tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, false));
  70         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  71         let bb_data = &fx.mir.basic_blocks()[START_BLOCK];
  72         let destination = match &bb_data.terminator().kind {
  73             TerminatorKind::Call {
  74                 func,
  75                 args,
  76                 destination,
  77                 cleanup: _,
  78                 from_hir_call: _,
  79             } => {
  80                 assert_eq!(args.len(), 2);
  81
  82                 let closure_arg = Local::new(1);
  83                 let closure_local = args[0].place().unwrap().as_local().unwrap();
  84                 assert_eq!(fx.mir.local_decls[closure_local].ty, fx.mir.local_decls[closure_arg].ty.builtin_deref(true).unwrap().ty);
  85                 let closure_deref = fx.local_map[&closure_arg].place_deref(&mut fx);
  86                 fx.local_map.insert(closure_local, closure_deref);
  87
  88                 let args_arg = Local::new(2);
  89                 let args_local = args[1].place().unwrap().as_local().unwrap();
  90                 assert_eq!(fx.mir.local_decls[args_local].ty, fx.mir.local_decls[args_arg].ty);
  91                 fx.local_map.insert(args_local, fx.local_map[&args_arg]);
  92
  93                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
  94                     &mut fx,
  95                     bb_data.terminator().source_info.span,
  96                     func,
  97                     args,
  98                     destination,
  99                 ));
 100                 destination.map(|(_ret_place, ret_block)| ret_block)
 101             }
 102             _ => unreachable!(),
 103         };
 104
 105         let destination = if let Some(destination) = destination {
 106             fx.bcx.switch_to_block(fx.block_map[destination]);
 107             let bb_data = &fx.mir.basic_blocks()[destination];
 108             match &bb_data.terminator().kind {
 109                 TerminatorKind::Call {
 110                     func,
 111                     args,
 112                     destination,
 113                     cleanup: _,
 114                     from_hir_call: _,
 115                 } => {
 116                     match destination {
 117                         Some((ret_place, _ret_block)) => {
 118                             fx.local_map.insert(ret_place.as_local().unwrap(), CPlace::no_place(fx.layout_of(fx.tcx.mk_unit())));
 119                         }
 120                         None => {}
 121                     }
 122
 123                     assert_eq!(args.len(), 1);
 124                     fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 125                         &mut fx,
 126                         bb_data.terminator().source_info.span,
 127                         func,
 128                         args,
 129                         destination,
 130                     ));
 131                     destination.map(|(_ret_place, ret_block)| ret_block)
 132                 }
 133                 _ => unreachable!(),
 134             }
 135         } else {
 136             None
 137         };
 138
 139         if let Some(destination) = destination {
 140             fx.bcx.switch_to_block(fx.block_map[destination]);
 141             let bb_data = &fx.mir.basic_blocks()[destination];
 142             match &bb_data.terminator().kind {
 143                 TerminatorKind::Return => crate::abi::codegen_return(&mut fx),
 144                 _ => unreachable!(),
 145             }
 146         }
 147     } else {
 148         tcx.sess.time("codegen clif ir", || {
 149             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, true));
 150             codegen_fn_content(&mut fx);
 151         });
 152     }
 153
 154     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 155     let instance = fx.instance;
 156     let mut clif_comments = fx.clif_comments;
 157     let source_info_set = fx.source_info_set;
 158     let local_map = fx.local_map;
 159     let cold_blocks = fx.cold_blocks;
 160
 161     #[cfg(debug_assertions)]
 162     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
 163
 164     // Verify function
 165     verify_func(tcx, &clif_comments, &context.func);
 166
 167     // Perform rust specific optimizations
 168     tcx.sess.time("optimize clif ir", || {
 169         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
 170     });
 171
 172     // Define function
 173     let module = &mut cx.module;
 174     tcx.sess.time(
 175         "define function",
 176         || module.define_function(
 177             func_id,
 178             context,
 179             &mut cranelift_codegen::binemit::NullTrapSink {},
 180         ).unwrap(),
 181     );
 182
 183     // Write optimized function to file for debugging
 184     #[cfg(debug_assertions)]
 185     {
 186         let value_ranges = context
 187             .build_value_labels_ranges(cx.module.isa())
 188             .expect("value location ranges");
 189
 190         crate::pretty_clif::write_clif_file(
 191             cx.tcx,
 192             "opt",
 193             instance,
 194             &context.func,
 195             &clif_comments,
 196             Some(&value_ranges),
 197         );
 198     }
 199
 200     // Define debuginfo for function
 201     let isa = cx.module.isa();
 202     tcx.sess.time("generate debug info", || {
 203         debug_context
 204             .as_mut()
 205             .map(|x| x.define(context, isa, &source_info_set, local_map));
 206     });
 207
 208     // Clear context to make it usable for the next function
 209     context.clear();
 210 }
 211
 212 pub(crate) fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 213     tcx.sess.time("verify clif ir", || {
 214         let flags = settings::Flags::new(settings::builder());
 215         match ::cranelift_codegen::verify_function(&func, &flags) {
 216             Ok(_) => {}
 217             Err(err) => {
 218                 tcx.sess.err(&format!("{:?}", err));
 219                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 220                     &func,
 221                     None,
 222                     Some(Box::new(writer)),
 223                     err,
 224                 );
 225                 tcx.sess
 226                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 227             }
 228         }
 229     });
 230 }
 231
 232 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 233     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 234         let block = fx.get_block(bb);
 235         fx.bcx.switch_to_block(block);
 236
 237         if bb_data.is_cleanup {
 238             // Unwinding after panicking is not supported
 239             continue;
 240
 241             // FIXME once unwinding is supported uncomment next lines
 242             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 243             // fx.cold_blocks.insert(block);
 244         }
 245
 246         fx.bcx.ins().nop();
 247         for stmt in &bb_data.statements {
 248             fx.set_debug_loc(stmt.source_info);
 249             trans_stmt(fx, block, stmt);
 250         }
 251
 252         #[cfg(debug_assertions)]
 253         {
 254             let mut terminator_head = "\n".to_string();
 255             bb_data
 256                 .terminator()
 257                 .kind
 258                 .fmt_head(&mut terminator_head)
 259                 .unwrap();
 260             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 261             fx.add_comment(inst, terminator_head);
 262         }
 263
 264         fx.set_debug_loc(bb_data.terminator().source_info);
 265
 266         match &bb_data.terminator().kind {
 267             TerminatorKind::Goto { target } => {
 268                 let block = fx.get_block(*target);
 269                 fx.bcx.ins().jump(block, &[]);
 270             }
 271             TerminatorKind::Return => {
 272                 crate::abi::codegen_return(fx);
 273             }
 274             TerminatorKind::Assert {
 275                 cond,
 276                 expected,
 277                 msg,
 278                 target,
 279                 cleanup: _,
 280             } => {
 281                 if !fx.tcx.sess.overflow_checks() {
 282                     if let mir::AssertKind::OverflowNeg = *msg {
 283                         let target = fx.get_block(*target);
 284                         fx.bcx.ins().jump(target, &[]);
 285                         continue;
 286                     }
 287                 }
 288                 let cond = trans_operand(fx, cond).load_scalar(fx);
 289
 290                 let target = fx.get_block(*target);
 291                 let failure = fx.bcx.create_block();
 292                 fx.cold_blocks.insert(failure);
 293
 294                 if *expected {
 295                     fx.bcx.ins().brz(cond, failure, &[]);
 296                 } else {
 297                     fx.bcx.ins().brnz(cond, failure, &[]);
 298                 };
 299                 fx.bcx.ins().jump(target, &[]);
 300
 301                 fx.bcx.switch_to_block(failure);
 302                 trap_panic(
 303                     fx,
 304                     format!(
 305                         "[panic] Assert {:?} at {:?} failed.",
 306                         msg,
 307                         bb_data.terminator().source_info.span
 308                     ),
 309                 );
 310             }
 311
 312             TerminatorKind::SwitchInt {
 313                 discr,
 314                 switch_ty: _,
 315                 values,
 316                 targets,
 317             } => {
 318                 let discr = trans_operand(fx, discr).load_scalar(fx);
 319                 let mut switch = ::cranelift_frontend::Switch::new();
 320                 for (i, value) in values.iter().enumerate() {
 321                     let block = fx.get_block(targets[i]);
 322                     switch.set_entry(*value as u64, block);
 323                 }
 324                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 325                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 326             }
 327             TerminatorKind::Call {
 328                 func,
 329                 args,
 330                 destination,
 331                 cleanup: _,
 332                 from_hir_call: _,
 333             } => {
 334                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 335                     fx,
 336                     bb_data.terminator().source_info.span,
 337                     func,
 338                     args,
 339                     destination,
 340                 ));
 341             }
 342             TerminatorKind::Resume | TerminatorKind::Abort => {
 343                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 344             }
 345             TerminatorKind::Unreachable => {
 346                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 347             }
 348             TerminatorKind::Yield { .. }
 349             | TerminatorKind::FalseEdges { .. }
 350             | TerminatorKind::FalseUnwind { .. }
 351             | TerminatorKind::DropAndReplace { .. }
 352             | TerminatorKind::GeneratorDrop => {
 353                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 354             }
 355             TerminatorKind::Drop {
 356                 location,
 357                 target,
 358                 unwind: _,
 359             } => {
 360                 let drop_place = trans_place(fx, location);
 361                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 362
 363                 let target_block = fx.get_block(*target);
 364                 fx.bcx.ins().jump(target_block, &[]);
 365             }
 366         };
 367     }
 368
 369     fx.bcx.seal_all_blocks();
 370     fx.bcx.finalize();
 371 }
 372
 373 fn trans_stmt<'tcx>(
 374     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 375     #[allow(unused_variables)]
 376     cur_block: Block,
 377     stmt: &Statement<'tcx>,
 378 ) {
 379     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 380
 381     fx.set_debug_loc(stmt.source_info);
 382
 383     #[cfg(false_debug_assertions)]
 384     match &stmt.kind {
 385         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 386         _ => {
 387             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 388             fx.add_comment(inst, format!("{:?}", stmt));
 389         }
 390     }
 391
 392     match &stmt.kind {
 393         StatementKind::SetDiscriminant {
 394             place,
 395             variant_index,
 396         } => {
 397             let place = trans_place(fx, place);
 398             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 399         }
 400         StatementKind::Assign(to_place_and_rval) => {
 401             let lval = trans_place(fx, &to_place_and_rval.0);
 402             let dest_layout = lval.layout();
 403             match &to_place_and_rval.1 {
 404                 Rvalue::Use(operand) => {
 405                     let val = trans_operand(fx, operand);
 406                     lval.write_cvalue(fx, val);
 407                 }
 408                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 409                     let place = trans_place(fx, place);
 410                     place.write_place_ref(fx, lval);
 411                 }
 412                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 413                     let lhs = trans_operand(fx, lhs);
 414                     let rhs = trans_operand(fx, rhs);
 415
 416                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 417                     lval.write_cvalue(fx, res);
 418                 }
 419                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 420                     let lhs = trans_operand(fx, lhs);
 421                     let rhs = trans_operand(fx, rhs);
 422
 423                     let res = if !fx.tcx.sess.overflow_checks() {
 424                         let val =
 425                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 426                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 427                         CValue::by_val_pair(val, is_overflow, lval.layout())
 428                     } else {
 429                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 430                     };
 431
 432                     lval.write_cvalue(fx, res);
 433                 }
 434                 Rvalue::UnaryOp(un_op, operand) => {
 435                     let operand = trans_operand(fx, operand);
 436                     let layout = operand.layout();
 437                     let val = operand.load_scalar(fx);
 438                     let res = match un_op {
 439                         UnOp::Not => {
 440                             match layout.ty.kind {
 441                                 ty::Bool => {
 442                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 443                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 444                                 }
 445                                 ty::Uint(_) | ty::Int(_) => {
 446                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 447                                 }
 448                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 449                             }
 450                         }
 451                         UnOp::Neg => match layout.ty.kind {
 452                             ty::Int(IntTy::I128) => {
 453                                 // FIXME remove this case once ineg.i128 works
 454                                 let zero = CValue::const_val(fx, layout, 0);
 455                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 456                             }
 457                             ty::Int(_) => {
 458                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 459                             }
 460                             ty::Float(_) => {
 461                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 462                             }
 463                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 464                         },
 465                     };
 466                     lval.write_cvalue(fx, res);
 467                 }
 468                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 469                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 470                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 471                     match from_ty.kind {
 472                         ty::FnDef(def_id, substs) => {
 473                             let func_ref = fx.get_function_ref(
 474                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 475                                     .unwrap(),
 476                             );
 477                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 478                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 479                         }
 480                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 481                     }
 482                 }
 483                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 484                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 485                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 486                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 487                     let operand = trans_operand(fx, operand);
 488                     lval.write_cvalue(fx, operand.unchecked_cast_to(to_layout));
 489                 }
 490                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 491                     let operand = trans_operand(fx, operand);
 492                     let from_ty = operand.layout().ty;
 493                     let to_ty = fx.monomorphize(to_ty);
 494
 495                     fn is_fat_ptr<'tcx>(
 496                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 497                         ty: Ty<'tcx>,
 498                     ) -> bool {
 499                         ty.builtin_deref(true)
 500                             .map(
 501                                 |ty::TypeAndMut {
 502                                      ty: pointee_ty,
 503                                      mutbl: _,
 504                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 505                             )
 506                             .unwrap_or(false)
 507                     }
 508
 509                     if is_fat_ptr(fx, from_ty) {
 510                         if is_fat_ptr(fx, to_ty) {
 511                             // fat-ptr -> fat-ptr
 512                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 513                         } else {
 514                             // fat-ptr -> thin-ptr
 515                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 516                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 517                         }
 518                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 519                         // enum -> discriminant value
 520                         assert!(adt_def.is_enum());
 521                         match to_ty.kind {
 522                             ty::Uint(_) | ty::Int(_) => {}
 523                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 524                         }
 525
 526                         let discr = crate::discriminant::codegen_get_discriminant(
 527                             fx,
 528                             operand,
 529                             fx.layout_of(to_ty),
 530                         );
 531                         lval.write_cvalue(fx, discr);
 532                     } else {
 533                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 534                         let from = operand.load_scalar(fx);
 535
 536                         let res = clif_int_or_float_cast(
 537                             fx,
 538                             from,
 539                             type_sign(from_ty),
 540                             to_clif_ty,
 541                             type_sign(to_ty),
 542                         );
 543                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 544                     }
 545                 }
 546                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 547                     let operand = trans_operand(fx, operand);
 548                     match operand.layout().ty.kind {
 549                         ty::Closure(def_id, substs) => {
 550                             let instance = Instance::resolve_closure(
 551                                 fx.tcx,
 552                                 def_id,
 553                                 substs,
 554                                 ty::ClosureKind::FnOnce,
 555                             );
 556                             let func_ref = fx.get_function_ref(instance);
 557                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 558                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 559                         }
 560                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 561                     }
 562                 }
 563                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 564                     let operand = trans_operand(fx, operand);
 565                     operand.unsize_value(fx, lval);
 566                 }
 567                 Rvalue::Discriminant(place) => {
 568                     let place = trans_place(fx, place);
 569                     let value = place.to_cvalue(fx);
 570                     let discr =
 571                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 572                     lval.write_cvalue(fx, discr);
 573                 }
 574                 Rvalue::Repeat(operand, times) => {
 575                     let operand = trans_operand(fx, operand);
 576                     for i in 0..*times {
 577                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 578                         let to = lval.place_index(fx, index);
 579                         to.write_cvalue(fx, operand);
 580                     }
 581                 }
 582                 Rvalue::Len(place) => {
 583                     let place = trans_place(fx, place);
 584                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 585                     let len = codegen_array_len(fx, place);
 586                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 587                 }
 588                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 589                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 590
 591                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 592                     let content_ty = fx.monomorphize(content_ty);
 593                     let layout = fx.layout_of(content_ty);
 594                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 595                     let llalign = fx
 596                         .bcx
 597                         .ins()
 598                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 599                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 600
 601                     // Allocate space:
 602                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 603                         Ok(id) => id,
 604                         Err(s) => {
 605                             fx.tcx
 606                                 .sess
 607                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 608                         }
 609                     };
 610                     let instance = ty::Instance::mono(fx.tcx, def_id);
 611                     let func_ref = fx.get_function_ref(instance);
 612                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 613                     let ptr = fx.bcx.inst_results(call)[0];
 614                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 615                 }
 616                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 617                     assert!(lval
 618                         .layout()
 619                         .ty
 620                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 621                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 622                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 623                     lval.write_cvalue(fx, val);
 624                 }
 625                 Rvalue::Aggregate(kind, operands) => match **kind {
 626                     AggregateKind::Array(_ty) => {
 627                         for (i, operand) in operands.into_iter().enumerate() {
 628                             let operand = trans_operand(fx, operand);
 629                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 630                             let to = lval.place_index(fx, index);
 631                             to.write_cvalue(fx, operand);
 632                         }
 633                     }
 634                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 635                 },
 636             }
 637         }
 638         StatementKind::StorageLive(_)
 639         | StatementKind::StorageDead(_)
 640         | StatementKind::Nop
 641         | StatementKind::FakeRead(..)
 642         | StatementKind::Retag { .. }
 643         | StatementKind::AscribeUserType(..) => {}
 644
 645         StatementKind::InlineAsm(asm) => {
 646             use rustc_ast::ast::Name;
 647             let InlineAsm {
 648                 asm,
 649                 outputs: _,
 650                 inputs: _,
 651             } = &**asm;
 652             let rustc_hir::InlineAsmInner {
 653                 asm: asm_code, // Name
 654                 outputs,       // Vec<Name>
 655                 inputs,        // Vec<Name>
 656                 clobbers,      // Vec<Name>
 657                 volatile,      // bool
 658                 alignstack,    // bool
 659                 dialect: _,    // rustc_ast::ast::AsmDialect
 660                 asm_str_style: _,
 661             } = asm;
 662             match &*asm_code.as_str() {
 663                 "" => {
 664                     assert_eq!(inputs, &[Name::intern("r")]);
 665                     assert!(outputs.is_empty(), "{:?}", outputs);
 666
 667                     // Black box
 668                 }
 669                 "cpuid" | "cpuid\n" => {
 670                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 671
 672                     assert_eq!(outputs.len(), 4);
 673                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 674                         .iter()
 675                         .enumerate()
 676                     {
 677                         assert_eq!(&outputs[i].constraint.as_str(), c);
 678                         assert!(!outputs[i].is_rw);
 679                         assert!(!outputs[i].is_indirect);
 680                     }
 681
 682                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 683
 684                     assert!(!volatile);
 685                     assert!(!alignstack);
 686
 687                     crate::trap::trap_unimplemented(
 688                         fx,
 689                         "__cpuid_count arch intrinsic is not supported",
 690                     );
 691                 }
 692                 "xgetbv" => {
 693                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 694
 695                     assert_eq!(outputs.len(), 2);
 696                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 697                         assert_eq!(&outputs[i].constraint.as_str(), c);
 698                         assert!(!outputs[i].is_rw);
 699                         assert!(!outputs[i].is_indirect);
 700                     }
 701
 702                     assert_eq!(clobbers, &[]);
 703
 704                     assert!(!volatile);
 705                     assert!(!alignstack);
 706
 707                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 708                 }
 709                 _ => unimpl_fatal!(fx.tcx, stmt.source_info.span, "Inline assembly is not supported"),
 710             }
 711         }
 712     }
 713 }
 714
 715 fn codegen_array_len<'tcx>(
 716     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 717     place: CPlace<'tcx>,
 718 ) -> Value {
 719     match place.layout().ty.kind {
 720         ty::Array(_elem_ty, len) => {
 721             let len = fx.monomorphize(&len)
 722                 .eval(fx.tcx, ParamEnv::reveal_all())
 723                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 724             fx.bcx.ins().iconst(fx.pointer_type, len)
 725         }
 726         ty::Slice(_elem_ty) => place
 727             .to_ptr_maybe_unsized(fx)
 728             .1
 729             .expect("Length metadata for slice place"),
 730         _ => bug!("Rvalue::Len({:?})", place),
 731     }
 732 }
 733
 734 pub(crate) fn trans_place<'tcx>(
 735     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 736     place: &Place<'tcx>,
 737 ) -> CPlace<'tcx> {
 738     let mut cplace = fx.get_local_place(place.local);
 739
 740     for elem in &*place.projection {
 741         match *elem {
 742             PlaceElem::Deref => {
 743                 cplace = cplace.place_deref(fx);
 744             }
 745             PlaceElem::Field(field, _ty) => {
 746                 cplace = cplace.place_field(fx, field);
 747             }
 748             PlaceElem::Index(local) => {
 749                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 750                 cplace = cplace.place_index(fx, index);
 751             }
 752             PlaceElem::ConstantIndex {
 753                 offset,
 754                 min_length: _,
 755                 from_end,
 756             } => {
 757                 let index = if !from_end {
 758                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 759                 } else {
 760                     let len = codegen_array_len(fx, cplace);
 761                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 762                 };
 763                 cplace = cplace.place_index(fx, index);
 764             }
 765             PlaceElem::Subslice { from, to, from_end } => {
 766                 // These indices are generated by slice patterns.
 767                 // slice[from:-to] in Python terms.
 768
 769                 match cplace.layout().ty.kind {
 770                     ty::Array(elem_ty, _len) => {
 771                         assert!(!from_end, "array subslices are never `from_end`");
 772                         let elem_layout = fx.layout_of(elem_ty);
 773                         let ptr = cplace.to_ptr(fx);
 774                         cplace = CPlace::for_ptr(
 775                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 776                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 777                         );
 778                     }
 779                     ty::Slice(elem_ty) => {
 780                         assert!(from_end, "slice subslices should be `from_end`");
 781                         let elem_layout = fx.layout_of(elem_ty);
 782                         let (ptr, len) = cplace.to_ptr_maybe_unsized(fx);
 783                         let len = len.unwrap();
 784                         cplace = CPlace::for_ptr_with_extra(
 785                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 786                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 787                             cplace.layout(),
 788                         );
 789                     }
 790                     _ => unreachable!(),
 791                 }
 792             }
 793             PlaceElem::Downcast(_adt_def, variant) => {
 794                 cplace = cplace.downcast_variant(fx, variant);
 795             }
 796         }
 797     }
 798
 799     cplace
 800 }
 801
 802 pub(crate) fn trans_operand<'tcx>(
 803     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 804     operand: &Operand<'tcx>,
 805 ) -> CValue<'tcx> {
 806     match operand {
 807         Operand::Move(place) | Operand::Copy(place) => {
 808             let cplace = trans_place(fx, place);
 809             cplace.to_cvalue(fx)
 810         }
 811         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 812     }
 813 }