src/base.rs

   1 use rustc::ty::adjustment::PointerCast;
   2 use rustc_index::vec::IndexVec;
   3
   4 use crate::prelude::*;
   5
   6 pub 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("define function", || module.define_function(func_id, context).unwrap());
 175
 176     // Write optimized function to file for debugging
 177     #[cfg(debug_assertions)]
 178     {
 179         let value_ranges = context
 180             .build_value_labels_ranges(cx.module.isa())
 181             .expect("value location ranges");
 182
 183         crate::pretty_clif::write_clif_file(
 184             cx.tcx,
 185             "opt",
 186             instance,
 187             &context.func,
 188             &clif_comments,
 189             Some(&value_ranges),
 190         );
 191     }
 192
 193     // Define debuginfo for function
 194     let isa = cx.module.isa();
 195     tcx.sess.time("generate debug info", || {
 196         debug_context
 197             .as_mut()
 198             .map(|x| x.define(context, isa, &source_info_set, local_map));
 199     });
 200
 201     // Clear context to make it usable for the next function
 202     context.clear();
 203 }
 204
 205 pub fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 206     tcx.sess.time("verify clif ir", || {
 207         let flags = settings::Flags::new(settings::builder());
 208         match ::cranelift_codegen::verify_function(&func, &flags) {
 209             Ok(_) => {}
 210             Err(err) => {
 211                 tcx.sess.err(&format!("{:?}", err));
 212                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 213                     &func,
 214                     None,
 215                     Some(Box::new(writer)),
 216                     err,
 217                 );
 218                 tcx.sess
 219                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 220             }
 221         }
 222     });
 223 }
 224
 225 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 226     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 227         let block = fx.get_block(bb);
 228         fx.bcx.switch_to_block(block);
 229
 230         if bb_data.is_cleanup {
 231             // Unwinding after panicking is not supported
 232             continue;
 233
 234             // FIXME once unwinding is supported uncomment next lines
 235             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 236             // fx.cold_blocks.insert(block);
 237         }
 238
 239         fx.bcx.ins().nop();
 240         for stmt in &bb_data.statements {
 241             fx.set_debug_loc(stmt.source_info);
 242             trans_stmt(fx, block, stmt);
 243         }
 244
 245         #[cfg(debug_assertions)]
 246         {
 247             let mut terminator_head = "\n".to_string();
 248             bb_data
 249                 .terminator()
 250                 .kind
 251                 .fmt_head(&mut terminator_head)
 252                 .unwrap();
 253             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 254             fx.add_comment(inst, terminator_head);
 255         }
 256
 257         fx.set_debug_loc(bb_data.terminator().source_info);
 258
 259         match &bb_data.terminator().kind {
 260             TerminatorKind::Goto { target } => {
 261                 let block = fx.get_block(*target);
 262                 fx.bcx.ins().jump(block, &[]);
 263             }
 264             TerminatorKind::Return => {
 265                 crate::abi::codegen_return(fx);
 266             }
 267             TerminatorKind::Assert {
 268                 cond,
 269                 expected,
 270                 msg,
 271                 target,
 272                 cleanup: _,
 273             } => {
 274                 if !fx.tcx.sess.overflow_checks() {
 275                     if let mir::AssertKind::OverflowNeg = *msg {
 276                         let target = fx.get_block(*target);
 277                         fx.bcx.ins().jump(target, &[]);
 278                         continue;
 279                     }
 280                 }
 281                 let cond = trans_operand(fx, cond).load_scalar(fx);
 282
 283                 let target = fx.get_block(*target);
 284                 let failure = fx.bcx.create_block();
 285                 fx.cold_blocks.insert(failure);
 286
 287                 if *expected {
 288                     fx.bcx.ins().brz(cond, failure, &[]);
 289                 } else {
 290                     fx.bcx.ins().brnz(cond, failure, &[]);
 291                 };
 292                 fx.bcx.ins().jump(target, &[]);
 293
 294                 fx.bcx.switch_to_block(failure);
 295                 trap_panic(
 296                     fx,
 297                     format!(
 298                         "[panic] Assert {:?} at {:?} failed.",
 299                         msg,
 300                         bb_data.terminator().source_info.span
 301                     ),
 302                 );
 303             }
 304
 305             TerminatorKind::SwitchInt {
 306                 discr,
 307                 switch_ty: _,
 308                 values,
 309                 targets,
 310             } => {
 311                 let discr = trans_operand(fx, discr).load_scalar(fx);
 312                 let mut switch = ::cranelift_frontend::Switch::new();
 313                 for (i, value) in values.iter().enumerate() {
 314                     let block = fx.get_block(targets[i]);
 315                     switch.set_entry(*value as u64, block);
 316                 }
 317                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 318                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 319             }
 320             TerminatorKind::Call {
 321                 func,
 322                 args,
 323                 destination,
 324                 cleanup: _,
 325                 from_hir_call: _,
 326             } => {
 327                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 328                     fx,
 329                     bb_data.terminator().source_info.span,
 330                     func,
 331                     args,
 332                     destination,
 333                 ));
 334             }
 335             TerminatorKind::Resume | TerminatorKind::Abort => {
 336                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 337             }
 338             TerminatorKind::Unreachable => {
 339                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 340             }
 341             TerminatorKind::Yield { .. }
 342             | TerminatorKind::FalseEdges { .. }
 343             | TerminatorKind::FalseUnwind { .. }
 344             | TerminatorKind::DropAndReplace { .. }
 345             | TerminatorKind::GeneratorDrop => {
 346                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 347             }
 348             TerminatorKind::Drop {
 349                 location,
 350                 target,
 351                 unwind: _,
 352             } => {
 353                 let drop_place = trans_place(fx, location);
 354                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 355
 356                 let target_block = fx.get_block(*target);
 357                 fx.bcx.ins().jump(target_block, &[]);
 358             }
 359         };
 360     }
 361
 362     fx.bcx.seal_all_blocks();
 363     fx.bcx.finalize();
 364 }
 365
 366 fn trans_stmt<'tcx>(
 367     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 368     #[allow(unused_variables)]
 369     cur_block: Block,
 370     stmt: &Statement<'tcx>,
 371 ) {
 372     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 373
 374     fx.set_debug_loc(stmt.source_info);
 375
 376     #[cfg(false_debug_assertions)]
 377     match &stmt.kind {
 378         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 379         _ => {
 380             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 381             fx.add_comment(inst, format!("{:?}", stmt));
 382         }
 383     }
 384
 385     match &stmt.kind {
 386         StatementKind::SetDiscriminant {
 387             place,
 388             variant_index,
 389         } => {
 390             let place = trans_place(fx, place);
 391             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 392         }
 393         StatementKind::Assign(to_place_and_rval) => {
 394             let lval = trans_place(fx, &to_place_and_rval.0);
 395             let dest_layout = lval.layout();
 396             match &to_place_and_rval.1 {
 397                 Rvalue::Use(operand) => {
 398                     let val = trans_operand(fx, operand);
 399                     lval.write_cvalue(fx, val);
 400                 }
 401                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 402                     let place = trans_place(fx, place);
 403                     place.write_place_ref(fx, lval);
 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 val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 436                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 437                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 438                                 }
 439                                 ty::Uint(_) | ty::Int(_) => {
 440                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 441                                 }
 442                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 443                             }
 444                         }
 445                         UnOp::Neg => match layout.ty.kind {
 446                             ty::Int(IntTy::I128) => {
 447                                 // FIXME remove this case once ineg.i128 works
 448                                 let zero = CValue::const_val(fx, layout, 0);
 449                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 450                             }
 451                             ty::Int(_) => {
 452                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 453                             }
 454                             ty::Float(_) => {
 455                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 456                             }
 457                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 458                         },
 459                     };
 460                     lval.write_cvalue(fx, res);
 461                 }
 462                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 463                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 464                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 465                     match from_ty.kind {
 466                         ty::FnDef(def_id, substs) => {
 467                             let func_ref = fx.get_function_ref(
 468                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 469                                     .unwrap(),
 470                             );
 471                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 472                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 473                         }
 474                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 475                     }
 476                 }
 477                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 478                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 479                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 480                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 481                     let operand = trans_operand(fx, operand);
 482                     lval.write_cvalue(fx, operand.unchecked_cast_to(to_layout));
 483                 }
 484                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 485                     let operand = trans_operand(fx, operand);
 486                     let from_ty = operand.layout().ty;
 487                     let to_ty = fx.monomorphize(to_ty);
 488
 489                     fn is_fat_ptr<'tcx>(
 490                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 491                         ty: Ty<'tcx>,
 492                     ) -> bool {
 493                         ty.builtin_deref(true)
 494                             .map(
 495                                 |ty::TypeAndMut {
 496                                      ty: pointee_ty,
 497                                      mutbl: _,
 498                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 499                             )
 500                             .unwrap_or(false)
 501                     }
 502
 503                     if is_fat_ptr(fx, from_ty) {
 504                         if is_fat_ptr(fx, to_ty) {
 505                             // fat-ptr -> fat-ptr
 506                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 507                         } else {
 508                             // fat-ptr -> thin-ptr
 509                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 510                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 511                         }
 512                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 513                         // enum -> discriminant value
 514                         assert!(adt_def.is_enum());
 515                         match to_ty.kind {
 516                             ty::Uint(_) | ty::Int(_) => {}
 517                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 518                         }
 519
 520                         let discr = crate::discriminant::codegen_get_discriminant(
 521                             fx,
 522                             operand,
 523                             fx.layout_of(to_ty),
 524                         );
 525                         lval.write_cvalue(fx, discr);
 526                     } else {
 527                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 528                         let from = operand.load_scalar(fx);
 529
 530                         let res = clif_int_or_float_cast(
 531                             fx,
 532                             from,
 533                             type_sign(from_ty),
 534                             to_clif_ty,
 535                             type_sign(to_ty),
 536                         );
 537                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 538                     }
 539                 }
 540                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 541                     let operand = trans_operand(fx, operand);
 542                     match operand.layout().ty.kind {
 543                         ty::Closure(def_id, substs) => {
 544                             let instance = Instance::resolve_closure(
 545                                 fx.tcx,
 546                                 def_id,
 547                                 substs,
 548                                 ty::ClosureKind::FnOnce,
 549                             );
 550                             let func_ref = fx.get_function_ref(instance);
 551                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 552                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 553                         }
 554                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 555                     }
 556                 }
 557                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 558                     let operand = trans_operand(fx, operand);
 559                     operand.unsize_value(fx, lval);
 560                 }
 561                 Rvalue::Discriminant(place) => {
 562                     let place = trans_place(fx, place);
 563                     let value = place.to_cvalue(fx);
 564                     let discr =
 565                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 566                     lval.write_cvalue(fx, discr);
 567                 }
 568                 Rvalue::Repeat(operand, times) => {
 569                     let operand = trans_operand(fx, operand);
 570                     for i in 0..*times {
 571                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 572                         let to = lval.place_index(fx, index);
 573                         to.write_cvalue(fx, operand);
 574                     }
 575                 }
 576                 Rvalue::Len(place) => {
 577                     let place = trans_place(fx, place);
 578                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 579                     let len = codegen_array_len(fx, place);
 580                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 581                 }
 582                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 583                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 584
 585                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 586                     let content_ty = fx.monomorphize(content_ty);
 587                     let layout = fx.layout_of(content_ty);
 588                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 589                     let llalign = fx
 590                         .bcx
 591                         .ins()
 592                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 593                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 594
 595                     // Allocate space:
 596                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 597                         Ok(id) => id,
 598                         Err(s) => {
 599                             fx.tcx
 600                                 .sess
 601                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 602                         }
 603                     };
 604                     let instance = ty::Instance::mono(fx.tcx, def_id);
 605                     let func_ref = fx.get_function_ref(instance);
 606                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 607                     let ptr = fx.bcx.inst_results(call)[0];
 608                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 609                 }
 610                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 611                     assert!(lval
 612                         .layout()
 613                         .ty
 614                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 615                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 616                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 617                     lval.write_cvalue(fx, val);
 618                 }
 619                 Rvalue::Aggregate(kind, operands) => match **kind {
 620                     AggregateKind::Array(_ty) => {
 621                         for (i, operand) in operands.into_iter().enumerate() {
 622                             let operand = trans_operand(fx, operand);
 623                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 624                             let to = lval.place_index(fx, index);
 625                             to.write_cvalue(fx, operand);
 626                         }
 627                     }
 628                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 629                 },
 630             }
 631         }
 632         StatementKind::StorageLive(_)
 633         | StatementKind::StorageDead(_)
 634         | StatementKind::Nop
 635         | StatementKind::FakeRead(..)
 636         | StatementKind::Retag { .. }
 637         | StatementKind::AscribeUserType(..) => {}
 638
 639         StatementKind::InlineAsm(asm) => {
 640             use rustc_ast::ast::Name;
 641             let InlineAsm {
 642                 asm,
 643                 outputs: _,
 644                 inputs: _,
 645             } = &**asm;
 646             let rustc_hir::InlineAsmInner {
 647                 asm: asm_code, // Name
 648                 outputs,       // Vec<Name>
 649                 inputs,        // Vec<Name>
 650                 clobbers,      // Vec<Name>
 651                 volatile,      // bool
 652                 alignstack,    // bool
 653                 dialect: _,    // rustc_ast::ast::AsmDialect
 654                 asm_str_style: _,
 655             } = asm;
 656             match &*asm_code.as_str() {
 657                 "" => {
 658                     assert_eq!(inputs, &[Name::intern("r")]);
 659                     assert!(outputs.is_empty(), "{:?}", outputs);
 660
 661                     // Black box
 662                 }
 663                 "cpuid" | "cpuid\n" => {
 664                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 665
 666                     assert_eq!(outputs.len(), 4);
 667                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 668                         .iter()
 669                         .enumerate()
 670                     {
 671                         assert_eq!(&outputs[i].constraint.as_str(), c);
 672                         assert!(!outputs[i].is_rw);
 673                         assert!(!outputs[i].is_indirect);
 674                     }
 675
 676                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 677
 678                     assert!(!volatile);
 679                     assert!(!alignstack);
 680
 681                     crate::trap::trap_unimplemented(
 682                         fx,
 683                         "__cpuid_count arch intrinsic is not supported",
 684                     );
 685                 }
 686                 "xgetbv" => {
 687                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 688
 689                     assert_eq!(outputs.len(), 2);
 690                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 691                         assert_eq!(&outputs[i].constraint.as_str(), c);
 692                         assert!(!outputs[i].is_rw);
 693                         assert!(!outputs[i].is_indirect);
 694                     }
 695
 696                     assert_eq!(clobbers, &[]);
 697
 698                     assert!(!volatile);
 699                     assert!(!alignstack);
 700
 701                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 702                 }
 703                 _ => unimpl!("Inline assembly is not supported"),
 704             }
 705         }
 706     }
 707 }
 708
 709 fn codegen_array_len<'tcx>(
 710     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 711     place: CPlace<'tcx>,
 712 ) -> Value {
 713     match place.layout().ty.kind {
 714         ty::Array(_elem_ty, len) => {
 715             let len = fx.monomorphize(&len)
 716                 .eval(fx.tcx, ParamEnv::reveal_all())
 717                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 718             fx.bcx.ins().iconst(fx.pointer_type, len)
 719         }
 720         ty::Slice(_elem_ty) => place
 721             .to_ptr_maybe_unsized(fx)
 722             .1
 723             .expect("Length metadata for slice place"),
 724         _ => bug!("Rvalue::Len({:?})", place),
 725     }
 726 }
 727
 728 pub fn trans_place<'tcx>(
 729     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 730     place: &Place<'tcx>,
 731 ) -> CPlace<'tcx> {
 732     let mut cplace = fx.get_local_place(place.local);
 733
 734     for elem in &*place.projection {
 735         match *elem {
 736             PlaceElem::Deref => {
 737                 cplace = cplace.place_deref(fx);
 738             }
 739             PlaceElem::Field(field, _ty) => {
 740                 cplace = cplace.place_field(fx, field);
 741             }
 742             PlaceElem::Index(local) => {
 743                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 744                 cplace = cplace.place_index(fx, index);
 745             }
 746             PlaceElem::ConstantIndex {
 747                 offset,
 748                 min_length: _,
 749                 from_end,
 750             } => {
 751                 let index = if !from_end {
 752                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 753                 } else {
 754                     let len = codegen_array_len(fx, cplace);
 755                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 756                 };
 757                 cplace = cplace.place_index(fx, index);
 758             }
 759             PlaceElem::Subslice { from, to, from_end } => {
 760                 // These indices are generated by slice patterns.
 761                 // slice[from:-to] in Python terms.
 762
 763                 match cplace.layout().ty.kind {
 764                     ty::Array(elem_ty, _len) => {
 765                         assert!(!from_end, "array subslices are never `from_end`");
 766                         let elem_layout = fx.layout_of(elem_ty);
 767                         let ptr = cplace.to_ptr(fx);
 768                         cplace = CPlace::for_ptr(
 769                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 770                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 771                         );
 772                     }
 773                     ty::Slice(elem_ty) => {
 774                         assert!(from_end, "slice subslices should be `from_end`");
 775                         let elem_layout = fx.layout_of(elem_ty);
 776                         let (ptr, len) = cplace.to_ptr_maybe_unsized(fx);
 777                         let len = len.unwrap();
 778                         cplace = CPlace::for_ptr_with_extra(
 779                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 780                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 781                             cplace.layout(),
 782                         );
 783                     }
 784                     _ => unreachable!(),
 785                 }
 786             }
 787             PlaceElem::Downcast(_adt_def, variant) => {
 788                 cplace = cplace.downcast_variant(fx, variant);
 789             }
 790         }
 791     }
 792
 793     cplace
 794 }
 795
 796 pub fn trans_operand<'tcx>(
 797     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 798     operand: &Operand<'tcx>,
 799 ) -> CValue<'tcx> {
 800     match operand {
 801         Operand::Move(place) | Operand::Copy(place) => {
 802             let cplace = trans_place(fx, place);
 803             cplace.to_cvalue(fx)
 804         }
 805         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 806     }
 807 }