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 ebb's
  33     let start_ebb = bcx.create_ebb();
  34     let ebb_map: IndexVec<BasicBlock, Ebb> = (0..mir.basic_blocks().len()).map(|_| bcx.create_ebb()).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         ebb_map,
  50         local_map: HashMap::new(),
  51         caller_location: None, // set by `codegen_fn_prelude`
  52         cold_ebbs: 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     if fx.mir.args_iter().any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited()) {
  61         let entry_block = fx.bcx.create_ebb();
  62         fx.bcx.append_ebb_params_for_function_params(entry_block);
  63         fx.bcx.switch_to_block(entry_block);
  64         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  65     } else {
  66         tcx.sess.time("codegen clif ir", || {
  67             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_ebb));
  68             codegen_fn_content(&mut fx);
  69         });
  70     }
  71
  72     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  73     let instance = fx.instance;
  74     let mut clif_comments = fx.clif_comments;
  75     let source_info_set = fx.source_info_set;
  76     let local_map = fx.local_map;
  77     let cold_ebbs = fx.cold_ebbs;
  78
  79     #[cfg(debug_assertions)]
  80     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
  81
  82     // Verify function
  83     verify_func(tcx, &clif_comments, &context.func);
  84
  85     // Perform rust specific optimizations
  86     tcx.sess.time("optimize clif ir", || {
  87         crate::optimize::optimize_function(tcx, instance, context, &cold_ebbs, &mut clif_comments);
  88     });
  89
  90     // Define function
  91     let module = &mut cx.module;
  92     tcx.sess.time("define function", || module.define_function(func_id, context).unwrap());
  93
  94     // Write optimized function to file for debugging
  95     #[cfg(debug_assertions)]
  96     {
  97         let value_ranges = context
  98             .build_value_labels_ranges(cx.module.isa())
  99             .expect("value location ranges");
 100
 101         crate::pretty_clif::write_clif_file(
 102             cx.tcx,
 103             "opt",
 104             instance,
 105             &context.func,
 106             &clif_comments,
 107             Some(&value_ranges),
 108         );
 109     }
 110
 111     // Define debuginfo for function
 112     let isa = cx.module.isa();
 113     tcx.sess.time("generate debug info", || {
 114         debug_context
 115             .as_mut()
 116             .map(|x| x.define(context, isa, &source_info_set, local_map));
 117     });
 118
 119     // Clear context to make it usable for the next function
 120     context.clear();
 121 }
 122
 123 pub fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 124     tcx.sess.time("verify clif ir", || {
 125         let flags = settings::Flags::new(settings::builder());
 126         match ::cranelift_codegen::verify_function(&func, &flags) {
 127             Ok(_) => {}
 128             Err(err) => {
 129                 tcx.sess.err(&format!("{:?}", err));
 130                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 131                     &func,
 132                     None,
 133                     Some(Box::new(writer)),
 134                     err,
 135                 );
 136                 tcx.sess
 137                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 138             }
 139         }
 140     });
 141 }
 142
 143 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 144     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 145         let ebb = fx.get_ebb(bb);
 146         fx.bcx.switch_to_block(ebb);
 147
 148         if bb_data.is_cleanup {
 149             // Unwinding after panicking is not supported
 150             continue;
 151
 152             // FIXME once unwinding is supported uncomment next lines
 153             // // Unwinding is unlikely to happen, so mark cleanup ebb's as cold.
 154             // fx.cold_ebbs.insert(ebb);
 155         }
 156
 157         fx.bcx.ins().nop();
 158         for stmt in &bb_data.statements {
 159             fx.set_debug_loc(stmt.source_info);
 160             trans_stmt(fx, ebb, stmt);
 161         }
 162
 163         #[cfg(debug_assertions)]
 164         {
 165             let mut terminator_head = "\n".to_string();
 166             bb_data
 167                 .terminator()
 168                 .kind
 169                 .fmt_head(&mut terminator_head)
 170                 .unwrap();
 171             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 172             fx.add_comment(inst, terminator_head);
 173         }
 174
 175         fx.set_debug_loc(bb_data.terminator().source_info);
 176
 177         match &bb_data.terminator().kind {
 178             TerminatorKind::Goto { target } => {
 179                 let ebb = fx.get_ebb(*target);
 180                 fx.bcx.ins().jump(ebb, &[]);
 181             }
 182             TerminatorKind::Return => {
 183                 crate::abi::codegen_return(fx);
 184             }
 185             TerminatorKind::Assert {
 186                 cond,
 187                 expected,
 188                 msg,
 189                 target,
 190                 cleanup: _,
 191             } => {
 192                 if !fx.tcx.sess.overflow_checks() {
 193                     if let mir::interpret::PanicInfo::OverflowNeg = *msg {
 194                         let target = fx.get_ebb(*target);
 195                         fx.bcx.ins().jump(target, &[]);
 196                         continue;
 197                     }
 198                 }
 199                 let cond = trans_operand(fx, cond).load_scalar(fx);
 200
 201                 let target = fx.get_ebb(*target);
 202                 let failure = fx.bcx.create_ebb();
 203                 fx.cold_ebbs.insert(failure);
 204
 205                 if *expected {
 206                     fx.bcx.ins().brz(cond, failure, &[]);
 207                 } else {
 208                     fx.bcx.ins().brnz(cond, failure, &[]);
 209                 };
 210                 fx.bcx.ins().jump(target, &[]);
 211
 212                 fx.bcx.switch_to_block(failure);
 213                 trap_panic(
 214                     fx,
 215                     format!(
 216                         "[panic] Assert {:?} at {:?} failed.",
 217                         msg,
 218                         bb_data.terminator().source_info.span
 219                     ),
 220                 );
 221             }
 222
 223             TerminatorKind::SwitchInt {
 224                 discr,
 225                 switch_ty: _,
 226                 values,
 227                 targets,
 228             } => {
 229                 let discr = trans_operand(fx, discr).load_scalar(fx);
 230                 let mut switch = ::cranelift_frontend::Switch::new();
 231                 for (i, value) in values.iter().enumerate() {
 232                     let ebb = fx.get_ebb(targets[i]);
 233                     switch.set_entry(*value as u64, ebb);
 234                 }
 235                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 236                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 237             }
 238             TerminatorKind::Call {
 239                 func,
 240                 args,
 241                 destination,
 242                 cleanup: _,
 243                 from_hir_call: _,
 244             } => {
 245                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 246                     fx,
 247                     bb_data.terminator().source_info.span,
 248                     func,
 249                     args,
 250                     destination,
 251                 ));
 252             }
 253             TerminatorKind::Resume | TerminatorKind::Abort => {
 254                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 255             }
 256             TerminatorKind::Unreachable => {
 257                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 258             }
 259             TerminatorKind::Yield { .. }
 260             | TerminatorKind::FalseEdges { .. }
 261             | TerminatorKind::FalseUnwind { .. }
 262             | TerminatorKind::DropAndReplace { .. }
 263             | TerminatorKind::GeneratorDrop => {
 264                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 265             }
 266             TerminatorKind::Drop {
 267                 location,
 268                 target,
 269                 unwind: _,
 270             } => {
 271                 let drop_place = trans_place(fx, location);
 272                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 273
 274                 let target_ebb = fx.get_ebb(*target);
 275                 fx.bcx.ins().jump(target_ebb, &[]);
 276             }
 277         };
 278     }
 279
 280     fx.bcx.seal_all_blocks();
 281     fx.bcx.finalize();
 282 }
 283
 284 fn trans_stmt<'tcx>(
 285     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 286     cur_ebb: Ebb,
 287     stmt: &Statement<'tcx>,
 288 ) {
 289     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 290
 291     fx.set_debug_loc(stmt.source_info);
 292
 293     #[cfg(false_debug_assertions)]
 294     match &stmt.kind {
 295         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 296         _ => {
 297             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 298             fx.add_comment(inst, format!("{:?}", stmt));
 299         }
 300     }
 301
 302     match &stmt.kind {
 303         StatementKind::SetDiscriminant {
 304             place,
 305             variant_index,
 306         } => {
 307             let place = trans_place(fx, place);
 308             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 309         }
 310         StatementKind::Assign(to_place_and_rval) => {
 311             let lval = trans_place(fx, &to_place_and_rval.0);
 312             let dest_layout = lval.layout();
 313             match &to_place_and_rval.1 {
 314                 Rvalue::Use(operand) => {
 315                     let val = trans_operand(fx, operand);
 316                     lval.write_cvalue(fx, val);
 317                 }
 318                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 319                     let place = trans_place(fx, place);
 320                     place.write_place_ref(fx, lval);
 321                 }
 322                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 323                     let lhs = trans_operand(fx, lhs);
 324                     let rhs = trans_operand(fx, rhs);
 325
 326                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 327                     lval.write_cvalue(fx, res);
 328                 }
 329                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 330                     let lhs = trans_operand(fx, lhs);
 331                     let rhs = trans_operand(fx, rhs);
 332
 333                     let res = if !fx.tcx.sess.overflow_checks() {
 334                         let val =
 335                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 336                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 337                         CValue::by_val_pair(val, is_overflow, lval.layout())
 338                     } else {
 339                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 340                     };
 341
 342                     lval.write_cvalue(fx, res);
 343                 }
 344                 Rvalue::UnaryOp(un_op, operand) => {
 345                     let operand = trans_operand(fx, operand);
 346                     let layout = operand.layout();
 347                     let val = operand.load_scalar(fx);
 348                     let res = match un_op {
 349                         UnOp::Not => {
 350                             match layout.ty.kind {
 351                                 ty::Bool => {
 352                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 353                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 354                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 355                                 }
 356                                 ty::Uint(_) | ty::Int(_) => {
 357                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 358                                 }
 359                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 360                             }
 361                         }
 362                         UnOp::Neg => match layout.ty.kind {
 363                             ty::Int(_) => {
 364                                 let zero = CValue::const_val(fx, layout, 0);
 365                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 366                             }
 367                             ty::Float(_) => {
 368                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 369                             }
 370                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 371                         },
 372                     };
 373                     lval.write_cvalue(fx, res);
 374                 }
 375                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 376                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 377                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 378                     match from_ty.kind {
 379                         ty::FnDef(def_id, substs) => {
 380                             let func_ref = fx.get_function_ref(
 381                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 382                                     .unwrap(),
 383                             );
 384                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 385                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 386                         }
 387                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 388                     }
 389                 }
 390                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 391                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 392                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 393                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 394                     let operand = trans_operand(fx, operand);
 395                     lval.write_cvalue(fx, operand.unchecked_cast_to(to_layout));
 396                 }
 397                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 398                     let operand = trans_operand(fx, operand);
 399                     let from_ty = operand.layout().ty;
 400                     let to_ty = fx.monomorphize(to_ty);
 401
 402                     fn is_fat_ptr<'tcx>(
 403                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 404                         ty: Ty<'tcx>,
 405                     ) -> bool {
 406                         ty.builtin_deref(true)
 407                             .map(
 408                                 |ty::TypeAndMut {
 409                                      ty: pointee_ty,
 410                                      mutbl: _,
 411                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 412                             )
 413                             .unwrap_or(false)
 414                     }
 415
 416                     if is_fat_ptr(fx, from_ty) {
 417                         if is_fat_ptr(fx, to_ty) {
 418                             // fat-ptr -> fat-ptr
 419                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 420                         } else {
 421                             // fat-ptr -> thin-ptr
 422                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 423                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 424                         }
 425                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 426                         // enum -> discriminant value
 427                         assert!(adt_def.is_enum());
 428                         match to_ty.kind {
 429                             ty::Uint(_) | ty::Int(_) => {}
 430                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 431                         }
 432
 433                         let discr = crate::discriminant::codegen_get_discriminant(
 434                             fx,
 435                             operand,
 436                             fx.layout_of(to_ty),
 437                         );
 438                         lval.write_cvalue(fx, discr);
 439                     } else {
 440                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 441                         let from = operand.load_scalar(fx);
 442
 443                         let res = clif_int_or_float_cast(
 444                             fx,
 445                             from,
 446                             type_sign(from_ty),
 447                             to_clif_ty,
 448                             type_sign(to_ty),
 449                         );
 450                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 451                     }
 452                 }
 453                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 454                     let operand = trans_operand(fx, operand);
 455                     match operand.layout().ty.kind {
 456                         ty::Closure(def_id, substs) => {
 457                             let instance = Instance::resolve_closure(
 458                                 fx.tcx,
 459                                 def_id,
 460                                 substs,
 461                                 ty::ClosureKind::FnOnce,
 462                             );
 463                             let func_ref = fx.get_function_ref(instance);
 464                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 465                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 466                         }
 467                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 468                     }
 469                 }
 470                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 471                     let operand = trans_operand(fx, operand);
 472                     operand.unsize_value(fx, lval);
 473                 }
 474                 Rvalue::Discriminant(place) => {
 475                     let place = trans_place(fx, place);
 476                     let value = place.to_cvalue(fx);
 477                     let discr =
 478                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 479                     lval.write_cvalue(fx, discr);
 480                 }
 481                 Rvalue::Repeat(operand, times) => {
 482                     let operand = trans_operand(fx, operand);
 483                     for i in 0..*times {
 484                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 485                         let to = lval.place_index(fx, index);
 486                         to.write_cvalue(fx, operand);
 487                     }
 488                 }
 489                 Rvalue::Len(place) => {
 490                     let place = trans_place(fx, place);
 491                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 492                     let len = codegen_array_len(fx, place);
 493                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 494                 }
 495                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 496                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 497
 498                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 499                     let content_ty = fx.monomorphize(content_ty);
 500                     let layout = fx.layout_of(content_ty);
 501                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 502                     let llalign = fx
 503                         .bcx
 504                         .ins()
 505                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 506                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 507
 508                     // Allocate space:
 509                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 510                         Ok(id) => id,
 511                         Err(s) => {
 512                             fx.tcx
 513                                 .sess
 514                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 515                         }
 516                     };
 517                     let instance = ty::Instance::mono(fx.tcx, def_id);
 518                     let func_ref = fx.get_function_ref(instance);
 519                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 520                     let ptr = fx.bcx.inst_results(call)[0];
 521                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 522                 }
 523                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 524                     assert!(lval
 525                         .layout()
 526                         .ty
 527                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 528                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 529                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 530                     lval.write_cvalue(fx, val);
 531                 }
 532                 Rvalue::Aggregate(kind, operands) => match **kind {
 533                     AggregateKind::Array(_ty) => {
 534                         for (i, operand) in operands.into_iter().enumerate() {
 535                             let operand = trans_operand(fx, operand);
 536                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 537                             let to = lval.place_index(fx, index);
 538                             to.write_cvalue(fx, operand);
 539                         }
 540                     }
 541                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 542                 },
 543             }
 544         }
 545         StatementKind::StorageLive(_)
 546         | StatementKind::StorageDead(_)
 547         | StatementKind::Nop
 548         | StatementKind::FakeRead(..)
 549         | StatementKind::Retag { .. }
 550         | StatementKind::AscribeUserType(..) => {}
 551
 552         StatementKind::InlineAsm(asm) => {
 553             use syntax::ast::Name;
 554             let InlineAsm {
 555                 asm,
 556                 outputs: _,
 557                 inputs: _,
 558             } = &**asm;
 559             let rustc_hir::InlineAsmInner {
 560                 asm: asm_code, // Name
 561                 outputs,       // Vec<Name>
 562                 inputs,        // Vec<Name>
 563                 clobbers,      // Vec<Name>
 564                 volatile,      // bool
 565                 alignstack,    // bool
 566                 dialect: _,    // syntax::ast::AsmDialect
 567                 asm_str_style: _,
 568             } = asm;
 569             match &*asm_code.as_str() {
 570                 "" => {
 571                     assert_eq!(inputs, &[Name::intern("r")]);
 572                     assert!(outputs.is_empty(), "{:?}", outputs);
 573
 574                     // Black box
 575                 }
 576                 "cpuid" | "cpuid\n" => {
 577                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 578
 579                     assert_eq!(outputs.len(), 4);
 580                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 581                         .iter()
 582                         .enumerate()
 583                     {
 584                         assert_eq!(&outputs[i].constraint.as_str(), c);
 585                         assert!(!outputs[i].is_rw);
 586                         assert!(!outputs[i].is_indirect);
 587                     }
 588
 589                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 590
 591                     assert!(!volatile);
 592                     assert!(!alignstack);
 593
 594                     crate::trap::trap_unimplemented(
 595                         fx,
 596                         "__cpuid_count arch intrinsic is not supported",
 597                     );
 598                 }
 599                 "xgetbv" => {
 600                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 601
 602                     assert_eq!(outputs.len(), 2);
 603                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 604                         assert_eq!(&outputs[i].constraint.as_str(), c);
 605                         assert!(!outputs[i].is_rw);
 606                         assert!(!outputs[i].is_indirect);
 607                     }
 608
 609                     assert_eq!(clobbers, &[]);
 610
 611                     assert!(!volatile);
 612                     assert!(!alignstack);
 613
 614                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 615                 }
 616                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__rust_probestack" => {
 617                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 618                 }
 619                 _ => unimpl!("Inline assembly is not supported"),
 620             }
 621         }
 622     }
 623 }
 624
 625 fn codegen_array_len<'tcx>(
 626     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 627     place: CPlace<'tcx>,
 628 ) -> Value {
 629     match place.layout().ty.kind {
 630         ty::Array(_elem_ty, len) => {
 631             let len = crate::constant::force_eval_const(fx, len)
 632                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 633             fx.bcx.ins().iconst(fx.pointer_type, len)
 634         }
 635         ty::Slice(_elem_ty) => place
 636             .to_ptr_maybe_unsized(fx)
 637             .1
 638             .expect("Length metadata for slice place"),
 639         _ => bug!("Rvalue::Len({:?})", place),
 640     }
 641 }
 642
 643 pub fn trans_place<'tcx>(
 644     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 645     place: &Place<'tcx>,
 646 ) -> CPlace<'tcx> {
 647     let mut cplace = fx.get_local_place(place.local);
 648
 649     for elem in &*place.projection {
 650         match *elem {
 651             PlaceElem::Deref => {
 652                 cplace = cplace.place_deref(fx);
 653             }
 654             PlaceElem::Field(field, _ty) => {
 655                 cplace = cplace.place_field(fx, field);
 656             }
 657             PlaceElem::Index(local) => {
 658                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 659                 cplace = cplace.place_index(fx, index);
 660             }
 661             PlaceElem::ConstantIndex {
 662                 offset,
 663                 min_length: _,
 664                 from_end,
 665             } => {
 666                 let index = if !from_end {
 667                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 668                 } else {
 669                     let len = codegen_array_len(fx, cplace);
 670                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 671                 };
 672                 cplace = cplace.place_index(fx, index);
 673             }
 674             PlaceElem::Subslice { from, to, from_end } => {
 675                 // These indices are generated by slice patterns.
 676                 // slice[from:-to] in Python terms.
 677
 678                 match cplace.layout().ty.kind {
 679                     ty::Array(elem_ty, _len) => {
 680                         assert!(!from_end, "array subslices are never `from_end`");
 681                         let elem_layout = fx.layout_of(elem_ty);
 682                         let ptr = cplace.to_ptr(fx);
 683                         cplace = CPlace::for_ptr(
 684                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 685                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 686                         );
 687                     }
 688                     ty::Slice(elem_ty) => {
 689                         assert!(from_end, "slice subslices should be `from_end`");
 690                         let elem_layout = fx.layout_of(elem_ty);
 691                         let (ptr, len) = cplace.to_ptr_maybe_unsized(fx);
 692                         let len = len.unwrap();
 693                         cplace = CPlace::for_ptr_with_extra(
 694                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 695                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 696                             cplace.layout(),
 697                         );
 698                     }
 699                     _ => unreachable!(),
 700                 }
 701             }
 702             PlaceElem::Downcast(_adt_def, variant) => {
 703                 cplace = cplace.downcast_variant(fx, variant);
 704             }
 705         }
 706     }
 707
 708     cplace
 709 }
 710
 711 pub fn trans_operand<'tcx>(
 712     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 713     operand: &Operand<'tcx>,
 714 ) -> CValue<'tcx> {
 715     match operand {
 716         Operand::Move(place) | Operand::Copy(place) => {
 717             let cplace = trans_place(fx, place);
 718             cplace.to_cvalue(fx)
 719         }
 720         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 721     }
 722 }