src/base.rs

   1 use rustc_middle::ty::adjustment::PointerCast;
   2 use rustc_index::vec::IndexVec;
   3
   4 use crate::prelude::*;
   5
   6 pub(crate) fn trans_fn<'tcx, B: Backend + 'static>(
   7     cx: &mut crate::CodegenCx<'tcx, B>,
   8     instance: Instance<'tcx>,
   9     linkage: Linkage,
  10 ) {
  11     let tcx = cx.tcx;
  12
  13     let mir = tcx.instance_mir(instance.def);
  14
  15     // Declare function
  16     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  17     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  18
  19     // Make FunctionBuilder
  20     let context = &mut cx.cached_context;
  21     context.clear();
  22     context.func.name = ExternalName::user(0, func_id.as_u32());
  23     context.func.signature = sig;
  24     context.func.collect_debug_info();
  25     let mut func_ctx = FunctionBuilderContext::new();
  26     let mut bcx = FunctionBuilder::new(&mut context.func, &mut func_ctx);
  27
  28     // Predefine blocks
  29     let start_block = bcx.create_block();
  30     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  31
  32     // Make FunctionCx
  33     let pointer_type = cx.module.target_config().pointer_type();
  34     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  35
  36     let mut fx = FunctionCx {
  37         tcx,
  38         module: &mut cx.module,
  39         pointer_type,
  40
  41         instance,
  42         mir,
  43
  44         bcx,
  45         block_map,
  46         local_map: FxHashMap::with_capacity_and_hasher(mir.local_decls.len(), Default::default()),
  47         caller_location: None, // set by `codegen_fn_prelude`
  48         cold_blocks: EntitySet::new(),
  49
  50         clif_comments,
  51         constants_cx: &mut cx.constants_cx,
  52         vtables: &mut cx.vtables,
  53         source_info_set: indexmap::IndexSet::new(),
  54     };
  55
  56     let arg_uninhabited = fx.mir.args_iter().any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  57
  58     if arg_uninhabited {
  59         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  60         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  61         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  62     } else {
  63         tcx.sess.time("codegen clif ir", || {
  64             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
  65             codegen_fn_content(&mut fx);
  66         });
  67     }
  68
  69     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  70     let instance = fx.instance;
  71     let mut clif_comments = fx.clif_comments;
  72     let source_info_set = fx.source_info_set;
  73     let local_map = fx.local_map;
  74     let cold_blocks = fx.cold_blocks;
  75
  76     crate::pretty_clif::write_clif_file(
  77         cx.tcx,
  78         "unopt",
  79         None,
  80         instance,
  81         &context,
  82         &clif_comments,
  83     );
  84
  85     // Verify function
  86     verify_func(tcx, &clif_comments, &context.func);
  87
  88     // Perform rust specific optimizations
  89     tcx.sess.time("optimize clif ir", || {
  90         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
  91     });
  92
  93     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
  94     // instruction, which doesn't have an encoding.
  95     context.compute_cfg();
  96     context.compute_domtree();
  97     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
  98
  99     // Define function
 100     let module = &mut cx.module;
 101     tcx.sess.time(
 102         "define function",
 103         || module.define_function(
 104             func_id,
 105             context,
 106             &mut cranelift_codegen::binemit::NullTrapSink {},
 107         ).unwrap(),
 108     );
 109
 110     // Write optimized function to file for debugging
 111     crate::pretty_clif::write_clif_file(
 112         cx.tcx,
 113         "opt",
 114         Some(cx.module.isa()),
 115         instance,
 116         &context,
 117         &clif_comments,
 118     );
 119
 120     // Define debuginfo for function
 121     let isa = cx.module.isa();
 122     let debug_context = &mut cx.debug_context;
 123     let unwind_context = &mut cx.unwind_context;
 124     tcx.sess.time("generate debug info", || {
 125         if let Some(debug_context) = debug_context {
 126             debug_context.define_function(instance, func_id, &name, isa, context, &source_info_set, local_map);
 127         }
 128         unwind_context.add_function(func_id, &context, isa);
 129     });
 130
 131     // Clear context to make it usable for the next function
 132     context.clear();
 133 }
 134
 135 pub(crate) fn verify_func(tcx: TyCtxt<'_>, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 136     tcx.sess.time("verify clif ir", || {
 137         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 138         match cranelift_codegen::verify_function(&func, &flags) {
 139             Ok(_) => {}
 140             Err(err) => {
 141                 tcx.sess.err(&format!("{:?}", err));
 142                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 143                     &func,
 144                     None,
 145                     Some(Box::new(writer)),
 146                     err,
 147                 );
 148                 tcx.sess
 149                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 150             }
 151         }
 152     });
 153 }
 154
 155 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 156     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 157         let block = fx.get_block(bb);
 158         fx.bcx.switch_to_block(block);
 159
 160         if bb_data.is_cleanup {
 161             // Unwinding after panicking is not supported
 162             continue;
 163
 164             // FIXME once unwinding is supported uncomment next lines
 165             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 166             // fx.cold_blocks.insert(block);
 167         }
 168
 169         fx.bcx.ins().nop();
 170         for stmt in &bb_data.statements {
 171             fx.set_debug_loc(stmt.source_info);
 172             trans_stmt(fx, block, stmt);
 173         }
 174
 175         #[cfg(debug_assertions)]
 176         {
 177             let mut terminator_head = "\n".to_string();
 178             bb_data
 179                 .terminator()
 180                 .kind
 181                 .fmt_head(&mut terminator_head)
 182                 .unwrap();
 183             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 184             fx.add_comment(inst, terminator_head);
 185         }
 186
 187         fx.set_debug_loc(bb_data.terminator().source_info);
 188
 189         match &bb_data.terminator().kind {
 190             TerminatorKind::Goto { target } => {
 191                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 192                     let mut can_immediately_return = true;
 193                     for stmt in &fx.mir[*target].statements {
 194                         if let StatementKind::StorageDead(_) = stmt.kind {
 195                         } else {
 196                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 197                             can_immediately_return = false;
 198                             break;
 199                         }
 200                     }
 201
 202                     if can_immediately_return {
 203                         crate::abi::codegen_return(fx);
 204                         continue;
 205                     }
 206                 }
 207
 208                 let block = fx.get_block(*target);
 209                 fx.bcx.ins().jump(block, &[]);
 210             }
 211             TerminatorKind::Return => {
 212                 crate::abi::codegen_return(fx);
 213             }
 214             TerminatorKind::Assert {
 215                 cond,
 216                 expected,
 217                 msg,
 218                 target,
 219                 cleanup: _,
 220             } => {
 221                 if !fx.tcx.sess.overflow_checks() {
 222                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 223                         let target = fx.get_block(*target);
 224                         fx.bcx.ins().jump(target, &[]);
 225                         continue;
 226                     }
 227                 }
 228                 let cond = trans_operand(fx, cond).load_scalar(fx);
 229
 230                 let target = fx.get_block(*target);
 231                 let failure = fx.bcx.create_block();
 232                 fx.cold_blocks.insert(failure);
 233
 234                 if *expected {
 235                     fx.bcx.ins().brz(cond, failure, &[]);
 236                 } else {
 237                     fx.bcx.ins().brnz(cond, failure, &[]);
 238                 };
 239                 fx.bcx.ins().jump(target, &[]);
 240
 241                 fx.bcx.switch_to_block(failure);
 242
 243                 let location = fx.get_caller_location(bb_data.terminator().source_info.span).load_scalar(fx);
 244
 245                 let args;
 246                 let lang_item = match msg {
 247                     AssertKind::BoundsCheck { ref len, ref index } => {
 248                         let len = trans_operand(fx, len).load_scalar(fx);
 249                         let index = trans_operand(fx, index).load_scalar(fx);
 250                         args = [index, len, location];
 251                         rustc_hir::lang_items::PanicBoundsCheckFnLangItem
 252                     }
 253                     _ => {
 254                         let msg_str = msg.description();
 255                         let msg_ptr = fx.anonymous_str("assert", msg_str);
 256                         let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 257                         args = [msg_ptr, msg_len, location];
 258                         rustc_hir::lang_items::PanicFnLangItem
 259                     }
 260                 };
 261
 262                 let def_id = fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| {
 263                     fx.tcx.sess.span_fatal(bb_data.terminator().source_info.span, &s)
 264                 });
 265
 266                 let instance = Instance::mono(fx.tcx, def_id);
 267                 let symbol_name = fx.tcx.symbol_name(instance).name.as_str();
 268
 269                 fx.lib_call(&*symbol_name, vec![fx.pointer_type, fx.pointer_type, fx.pointer_type], vec![], &args);
 270
 271                 crate::trap::trap_unreachable(fx, "panic lang item returned");
 272             }
 273
 274             TerminatorKind::SwitchInt {
 275                 discr,
 276                 switch_ty: _,
 277                 values,
 278                 targets,
 279             } => {
 280                 let discr = trans_operand(fx, discr).load_scalar(fx);
 281                 let mut switch = ::cranelift_frontend::Switch::new();
 282                 for (i, value) in values.iter().enumerate() {
 283                     let block = fx.get_block(targets[i]);
 284                     switch.set_entry(*value as u64, block);
 285                 }
 286                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 287                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 288             }
 289             TerminatorKind::Call {
 290                 func,
 291                 args,
 292                 destination,
 293                 fn_span,
 294                 cleanup: _,
 295                 from_hir_call: _,
 296             } => {
 297                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 298                     fx,
 299                     *fn_span,
 300                     block,
 301                     func,
 302                     args,
 303                     *destination,
 304                 ));
 305             }
 306             TerminatorKind::InlineAsm {
 307                 template,
 308                 operands,
 309                 options: _,
 310                 destination,
 311                 line_spans: _,
 312             } => {
 313                 match template {
 314                     &[] => {
 315                         assert_eq!(operands, &[]);
 316                         match *destination {
 317                             Some(destination) => {
 318                                 let destination_block = fx.get_block(destination);
 319                                 fx.bcx.ins().jump(destination_block, &[]);
 320                             }
 321                             None => bug!(),
 322                         }
 323
 324                         // Black box
 325                     }
 326                     _ => fx.tcx.sess.span_fatal(bb_data.terminator().source_info.span, "Inline assembly is not supported"),
 327                 }
 328             }
 329             TerminatorKind::Resume | TerminatorKind::Abort => {
 330                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 331             }
 332             TerminatorKind::Unreachable => {
 333                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 334             }
 335             TerminatorKind::Yield { .. }
 336             | TerminatorKind::FalseEdge { .. }
 337             | TerminatorKind::FalseUnwind { .. }
 338             | TerminatorKind::DropAndReplace { .. }
 339             | TerminatorKind::GeneratorDrop => {
 340                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 341             }
 342             TerminatorKind::Drop {
 343                 place,
 344                 target,
 345                 unwind: _,
 346             } => {
 347                 let drop_place = trans_place(fx, *place);
 348                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 349
 350                 let target_block = fx.get_block(*target);
 351                 fx.bcx.ins().jump(target_block, &[]);
 352             }
 353         };
 354     }
 355
 356     fx.bcx.seal_all_blocks();
 357     fx.bcx.finalize();
 358 }
 359
 360 fn trans_stmt<'tcx>(
 361     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 362     #[allow(unused_variables)]
 363     cur_block: Block,
 364     stmt: &Statement<'tcx>,
 365 ) {
 366     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 367
 368     fx.set_debug_loc(stmt.source_info);
 369
 370     #[cfg(false_debug_assertions)]
 371     match &stmt.kind {
 372         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 373         _ => {
 374             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 375             fx.add_comment(inst, format!("{:?}", stmt));
 376         }
 377     }
 378
 379     match &stmt.kind {
 380         StatementKind::SetDiscriminant {
 381             place,
 382             variant_index,
 383         } => {
 384             let place = trans_place(fx, **place);
 385             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 386         }
 387         StatementKind::Assign(to_place_and_rval) => {
 388             let lval = trans_place(fx, to_place_and_rval.0);
 389             let dest_layout = lval.layout();
 390             match &to_place_and_rval.1 {
 391                 Rvalue::Use(operand) => {
 392                     let val = trans_operand(fx, operand);
 393                     lval.write_cvalue(fx, val);
 394                 }
 395                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 396                     let place = trans_place(fx, *place);
 397                     place.write_place_ref(fx, lval);
 398                 }
 399                 Rvalue::ThreadLocalRef(def_id) => {
 400                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 401                     lval.write_cvalue(fx, val);
 402                 }
 403                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 404                     let lhs = trans_operand(fx, lhs);
 405                     let rhs = trans_operand(fx, rhs);
 406
 407                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 408                     lval.write_cvalue(fx, res);
 409                 }
 410                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 411                     let lhs = trans_operand(fx, lhs);
 412                     let rhs = trans_operand(fx, rhs);
 413
 414                     let res = if !fx.tcx.sess.overflow_checks() {
 415                         let val =
 416                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 417                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 418                         CValue::by_val_pair(val, is_overflow, lval.layout())
 419                     } else {
 420                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 421                     };
 422
 423                     lval.write_cvalue(fx, res);
 424                 }
 425                 Rvalue::UnaryOp(un_op, operand) => {
 426                     let operand = trans_operand(fx, operand);
 427                     let layout = operand.layout();
 428                     let val = operand.load_scalar(fx);
 429                     let res = match un_op {
 430                         UnOp::Not => {
 431                             match layout.ty.kind {
 432                                 ty::Bool => {
 433                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 434                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 435                                 }
 436                                 ty::Uint(_) | ty::Int(_) => {
 437                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 438                                 }
 439                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 440                             }
 441                         }
 442                         UnOp::Neg => match layout.ty.kind {
 443                             ty::Int(IntTy::I128) => {
 444                                 // FIXME remove this case once ineg.i128 works
 445                                 let zero = CValue::const_val(fx, layout, 0);
 446                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 447                             }
 448                             ty::Int(_) => {
 449                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 450                             }
 451                             ty::Float(_) => {
 452                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 453                             }
 454                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 455                         },
 456                     };
 457                     lval.write_cvalue(fx, res);
 458                 }
 459                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 460                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 461                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 462                     match from_ty.kind {
 463                         ty::FnDef(def_id, substs) => {
 464                             let func_ref = fx.get_function_ref(
 465                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 466                                     .unwrap(),
 467                             );
 468                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 469                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 470                         }
 471                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 472                     }
 473                 }
 474                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 475                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 476                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 477                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 478                     let operand = trans_operand(fx, operand);
 479                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 480                 }
 481                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 482                     let operand = trans_operand(fx, operand);
 483                     let from_ty = operand.layout().ty;
 484                     let to_ty = fx.monomorphize(to_ty);
 485
 486                     fn is_fat_ptr<'tcx>(
 487                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 488                         ty: Ty<'tcx>,
 489                     ) -> bool {
 490                         ty.builtin_deref(true)
 491                             .map(
 492                                 |ty::TypeAndMut {
 493                                      ty: pointee_ty,
 494                                      mutbl: _,
 495                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 496                             )
 497                             .unwrap_or(false)
 498                     }
 499
 500                     if is_fat_ptr(fx, from_ty) {
 501                         if is_fat_ptr(fx, to_ty) {
 502                             // fat-ptr -> fat-ptr
 503                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 504                         } else {
 505                             // fat-ptr -> thin-ptr
 506                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 507                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 508                         }
 509                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 510                         // enum -> discriminant value
 511                         assert!(adt_def.is_enum());
 512                         match to_ty.kind {
 513                             ty::Uint(_) | ty::Int(_) => {}
 514                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 515                         }
 516
 517                         let discr = crate::discriminant::codegen_get_discriminant(
 518                             fx,
 519                             operand,
 520                             fx.layout_of(to_ty),
 521                         );
 522                         lval.write_cvalue(fx, discr);
 523                     } else {
 524                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 525                         let from = operand.load_scalar(fx);
 526
 527                         let res = clif_int_or_float_cast(
 528                             fx,
 529                             from,
 530                             type_sign(from_ty),
 531                             to_clif_ty,
 532                             type_sign(to_ty),
 533                         );
 534                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 535                     }
 536                 }
 537                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 538                     let operand = trans_operand(fx, operand);
 539                     match operand.layout().ty.kind {
 540                         ty::Closure(def_id, substs) => {
 541                             let instance = Instance::resolve_closure(
 542                                 fx.tcx,
 543                                 def_id,
 544                                 substs,
 545                                 ty::ClosureKind::FnOnce,
 546                             );
 547                             let func_ref = fx.get_function_ref(instance);
 548                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 549                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 550                         }
 551                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 552                     }
 553                 }
 554                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 555                     let operand = trans_operand(fx, operand);
 556                     operand.unsize_value(fx, lval);
 557                 }
 558                 Rvalue::Discriminant(place) => {
 559                     let place = trans_place(fx, *place);
 560                     let value = place.to_cvalue(fx);
 561                     let discr =
 562                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 563                     lval.write_cvalue(fx, discr);
 564                 }
 565                 Rvalue::Repeat(operand, times) => {
 566                     let operand = trans_operand(fx, operand);
 567                     let times = fx
 568                         .monomorphize(times)
 569                         .eval(fx.tcx, ParamEnv::reveal_all())
 570                         .val
 571                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 572                         .unwrap();
 573                     for i in 0..times {
 574                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 575                         let to = lval.place_index(fx, index);
 576                         to.write_cvalue(fx, operand);
 577                     }
 578                 }
 579                 Rvalue::Len(place) => {
 580                     let place = trans_place(fx, *place);
 581                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 582                     let len = codegen_array_len(fx, place);
 583                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 584                 }
 585                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 586                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 587
 588                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 589                     let content_ty = fx.monomorphize(content_ty);
 590                     let layout = fx.layout_of(content_ty);
 591                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 592                     let llalign = fx
 593                         .bcx
 594                         .ins()
 595                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 596                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 597
 598                     // Allocate space:
 599                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 600                         Ok(id) => id,
 601                         Err(s) => {
 602                             fx.tcx
 603                                 .sess
 604                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 605                         }
 606                     };
 607                     let instance = ty::Instance::mono(fx.tcx, def_id);
 608                     let func_ref = fx.get_function_ref(instance);
 609                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 610                     let ptr = fx.bcx.inst_results(call)[0];
 611                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 612                 }
 613                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 614                     assert!(lval
 615                         .layout()
 616                         .ty
 617                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 618                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 619                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 620                     lval.write_cvalue(fx, val);
 621                 }
 622                 Rvalue::Aggregate(kind, operands) => match **kind {
 623                     AggregateKind::Array(_ty) => {
 624                         for (i, operand) in operands.into_iter().enumerate() {
 625                             let operand = trans_operand(fx, operand);
 626                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 627                             let to = lval.place_index(fx, index);
 628                             to.write_cvalue(fx, operand);
 629                         }
 630                     }
 631                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 632                 },
 633             }
 634         }
 635         StatementKind::StorageLive(_)
 636         | StatementKind::StorageDead(_)
 637         | StatementKind::Nop
 638         | StatementKind::FakeRead(..)
 639         | StatementKind::Retag { .. }
 640         | StatementKind::AscribeUserType(..) => {}
 641
 642         StatementKind::LlvmInlineAsm(asm) => {
 643             use rustc_span::symbol::Symbol;
 644             let LlvmInlineAsm {
 645                 asm,
 646                 outputs: _,
 647                 inputs: _,
 648             } = &**asm;
 649             let rustc_hir::LlvmInlineAsmInner {
 650                 asm: asm_code, // Name
 651                 outputs,       // Vec<Name>
 652                 inputs,        // Vec<Name>
 653                 clobbers,      // Vec<Name>
 654                 volatile,      // bool
 655                 alignstack,    // bool
 656                 dialect: _,    // rustc_ast::ast::AsmDialect
 657                 asm_str_style: _,
 658             } = asm;
 659             match &*asm_code.as_str() {
 660                 cpuid if cpuid.contains("cpuid") => {
 661                     crate::trap::trap_unimplemented(
 662                         fx,
 663                         "__cpuid_count arch intrinsic is not supported",
 664                     );
 665                 }
 666                 "xgetbv" => {
 667                     assert_eq!(inputs, &[Symbol::intern("{ecx}")]);
 668
 669                     assert_eq!(outputs.len(), 2);
 670                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 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, &[]);
 677
 678                     assert!(!volatile);
 679                     assert!(!alignstack);
 680
 681                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 682                 }
 683                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 684                 _ if fx.tcx.symbol_name(fx.instance).name.as_str().starts_with("___chkstk") => {
 685                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 686                 }
 687                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__alloca" => {
 688                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 689                 }
 690                 // Used in sys::windows::abort_internal
 691                 "int $$0x29" => {
 692                     crate::trap::trap_unimplemented(fx, "Windows abort");
 693                 }
 694                 _ => fx.tcx.sess.span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 695             }
 696         }
 697     }
 698 }
 699
 700 fn codegen_array_len<'tcx>(
 701     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 702     place: CPlace<'tcx>,
 703 ) -> Value {
 704     match place.layout().ty.kind {
 705         ty::Array(_elem_ty, len) => {
 706             let len = fx.monomorphize(&len)
 707                 .eval(fx.tcx, ParamEnv::reveal_all())
 708                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 709             fx.bcx.ins().iconst(fx.pointer_type, len)
 710         }
 711         ty::Slice(_elem_ty) => place
 712             .to_ptr_maybe_unsized()
 713             .1
 714             .expect("Length metadata for slice place"),
 715         _ => bug!("Rvalue::Len({:?})", place),
 716     }
 717 }
 718
 719 pub(crate) fn trans_place<'tcx>(
 720     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 721     place: Place<'tcx>,
 722 ) -> CPlace<'tcx> {
 723     let mut cplace = fx.get_local_place(place.local);
 724
 725     for elem in place.projection {
 726         match elem {
 727             PlaceElem::Deref => {
 728                 cplace = cplace.place_deref(fx);
 729             }
 730             PlaceElem::Field(field, _ty) => {
 731                 cplace = cplace.place_field(fx, field);
 732             }
 733             PlaceElem::Index(local) => {
 734                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 735                 cplace = cplace.place_index(fx, index);
 736             }
 737             PlaceElem::ConstantIndex {
 738                 offset,
 739                 min_length: _,
 740                 from_end,
 741             } => {
 742                 let index = if !from_end {
 743                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 744                 } else {
 745                     let len = codegen_array_len(fx, cplace);
 746                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 747                 };
 748                 cplace = cplace.place_index(fx, index);
 749             }
 750             PlaceElem::Subslice { from, to, from_end } => {
 751                 // These indices are generated by slice patterns.
 752                 // slice[from:-to] in Python terms.
 753
 754                 match cplace.layout().ty.kind {
 755                     ty::Array(elem_ty, _len) => {
 756                         assert!(!from_end, "array subslices are never `from_end`");
 757                         let elem_layout = fx.layout_of(elem_ty);
 758                         let ptr = cplace.to_ptr();
 759                         cplace = CPlace::for_ptr(
 760                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 761                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 762                         );
 763                     }
 764                     ty::Slice(elem_ty) => {
 765                         assert!(from_end, "slice subslices should be `from_end`");
 766                         let elem_layout = fx.layout_of(elem_ty);
 767                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 768                         let len = len.unwrap();
 769                         cplace = CPlace::for_ptr_with_extra(
 770                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 771                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 772                             cplace.layout(),
 773                         );
 774                     }
 775                     _ => unreachable!(),
 776                 }
 777             }
 778             PlaceElem::Downcast(_adt_def, variant) => {
 779                 cplace = cplace.downcast_variant(fx, variant);
 780             }
 781         }
 782     }
 783
 784     cplace
 785 }
 786
 787 pub(crate) fn trans_operand<'tcx>(
 788     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 789     operand: &Operand<'tcx>,
 790 ) -> CValue<'tcx> {
 791     match operand {
 792         Operand::Move(place) | Operand::Copy(place) => {
 793             let cplace = trans_place(fx, *place);
 794             cplace.to_cvalue(fx)
 795         }
 796         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 797     }
 798 }