src/base.rs

   1 use rustc_middle::ty::adjustment::PointerCast;
   2 use rustc_index::vec::IndexVec;
   3
   4 use crate::prelude::*;
   5
   6 pub(crate) fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
   7     cx: &mut crate::CodegenCx<'clif, 'tcx, B>,
   8     instance: Instance<'tcx>,
   9     linkage: Linkage,
  10 ) {
  11     let tcx = cx.tcx;
  12
  13     let mir = tcx.instance_mir(instance.def);
  14
  15     // Declare function
  16     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  17     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  18     let mut debug_context = cx
  19         .debug_context
  20         .as_mut()
  21         .map(|debug_context| FunctionDebugContext::new(debug_context, instance, func_id, &name));
  22
  23     // Make FunctionBuilder
  24     let context = &mut cx.cached_context;
  25     context.clear();
  26     context.func.name = ExternalName::user(0, func_id.as_u32());
  27     context.func.signature = sig;
  28     context.func.collect_debug_info();
  29     let mut func_ctx = FunctionBuilderContext::new();
  30     let mut bcx = FunctionBuilder::new(&mut context.func, &mut func_ctx);
  31
  32     // Predefine blocks
  33     let start_block = bcx.create_block();
  34     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  35
  36     // Make FunctionCx
  37     let pointer_type = cx.module.target_config().pointer_type();
  38     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  39
  40     let mut fx = FunctionCx {
  41         tcx,
  42         module: cx.module,
  43         pointer_type,
  44
  45         instance,
  46         mir,
  47
  48         bcx,
  49         block_map,
  50         local_map: FxHashMap::with_capacity_and_hasher(mir.local_decls.len(), Default::default()),
  51         caller_location: None, // set by `codegen_fn_prelude`
  52         cold_blocks: EntitySet::new(),
  53
  54         clif_comments,
  55         constants_cx: &mut cx.constants_cx,
  56         vtables: &mut cx.vtables,
  57         source_info_set: indexmap::IndexSet::new(),
  58     };
  59
  60     let arg_uninhabited = fx.mir.args_iter().any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  61
  62     if arg_uninhabited {
  63         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  64         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  65         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  66     } else {
  67         tcx.sess.time("codegen clif ir", || {
  68             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, true));
  69             codegen_fn_content(&mut fx);
  70         });
  71     }
  72
  73     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  74     let instance = fx.instance;
  75     let mut clif_comments = fx.clif_comments;
  76     let source_info_set = fx.source_info_set;
  77     let local_map = fx.local_map;
  78     let cold_blocks = fx.cold_blocks;
  79
  80     #[cfg(debug_assertions)]
  81     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
  82
  83     // Verify function
  84     verify_func(tcx, &clif_comments, &context.func);
  85
  86     // Perform rust specific optimizations
  87     tcx.sess.time("optimize clif ir", || {
  88         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
  89     });
  90
  91     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
  92     // instruction, which doesn't have an encoding.
  93     context.compute_cfg();
  94     context.compute_domtree();
  95     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
  96
  97     // Define function
  98     let module = &mut cx.module;
  99     tcx.sess.time(
 100         "define function",
 101         || module.define_function(
 102             func_id,
 103             context,
 104             &mut cranelift_codegen::binemit::NullTrapSink {},
 105         ).unwrap(),
 106     );
 107
 108     // Write optimized function to file for debugging
 109     #[cfg(debug_assertions)]
 110     {
 111         let value_ranges = context
 112             .build_value_labels_ranges(cx.module.isa())
 113             .expect("value location ranges");
 114
 115         crate::pretty_clif::write_clif_file(
 116             cx.tcx,
 117             "opt",
 118             instance,
 119             &context.func,
 120             &clif_comments,
 121             Some(&value_ranges),
 122         );
 123     }
 124
 125     // Define debuginfo for function
 126     let isa = cx.module.isa();
 127     tcx.sess.time("generate debug info", || {
 128         debug_context
 129             .as_mut()
 130             .map(|x| x.define(context, isa, &source_info_set, local_map));
 131     });
 132
 133     // Clear context to make it usable for the next function
 134     context.clear();
 135 }
 136
 137 pub(crate) fn verify_func(tcx: TyCtxt<'_>, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 138     tcx.sess.time("verify clif ir", || {
 139         let flags = settings::Flags::new(settings::builder());
 140         match ::cranelift_codegen::verify_function(&func, &flags) {
 141             Ok(_) => {}
 142             Err(err) => {
 143                 tcx.sess.err(&format!("{:?}", err));
 144                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 145                     &func,
 146                     None,
 147                     Some(Box::new(writer)),
 148                     err,
 149                 );
 150                 tcx.sess
 151                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 152             }
 153         }
 154     });
 155 }
 156
 157 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 158     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 159         let block = fx.get_block(bb);
 160         fx.bcx.switch_to_block(block);
 161
 162         if bb_data.is_cleanup {
 163             // Unwinding after panicking is not supported
 164             continue;
 165
 166             // FIXME once unwinding is supported uncomment next lines
 167             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 168             // fx.cold_blocks.insert(block);
 169         }
 170
 171         fx.bcx.ins().nop();
 172         for stmt in &bb_data.statements {
 173             fx.set_debug_loc(stmt.source_info);
 174             trans_stmt(fx, block, stmt);
 175         }
 176
 177         #[cfg(debug_assertions)]
 178         {
 179             let mut terminator_head = "\n".to_string();
 180             bb_data
 181                 .terminator()
 182                 .kind
 183                 .fmt_head(&mut terminator_head)
 184                 .unwrap();
 185             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 186             fx.add_comment(inst, terminator_head);
 187         }
 188
 189         fx.set_debug_loc(bb_data.terminator().source_info);
 190
 191         match &bb_data.terminator().kind {
 192             TerminatorKind::Goto { target } => {
 193                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 194                     let mut can_immediately_return = true;
 195                     for stmt in &fx.mir[*target].statements {
 196                         if let StatementKind::StorageDead(_) = stmt.kind {
 197                         } else {
 198                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 199                             can_immediately_return = false;
 200                             break;
 201                         }
 202                     }
 203
 204                     if can_immediately_return {
 205                         crate::abi::codegen_return(fx);
 206                         continue;
 207                     }
 208                 }
 209
 210                 let block = fx.get_block(*target);
 211                 fx.bcx.ins().jump(block, &[]);
 212             }
 213             TerminatorKind::Return => {
 214                 crate::abi::codegen_return(fx);
 215             }
 216             TerminatorKind::Assert {
 217                 cond,
 218                 expected,
 219                 msg,
 220                 target,
 221                 cleanup: _,
 222             } => {
 223                 if !fx.tcx.sess.overflow_checks() {
 224                     if let mir::AssertKind::OverflowNeg = *msg {
 225                         let target = fx.get_block(*target);
 226                         fx.bcx.ins().jump(target, &[]);
 227                         continue;
 228                     }
 229                 }
 230                 let cond = trans_operand(fx, cond).load_scalar(fx);
 231
 232                 let target = fx.get_block(*target);
 233                 let failure = fx.bcx.create_block();
 234                 fx.cold_blocks.insert(failure);
 235
 236                 if *expected {
 237                     fx.bcx.ins().brz(cond, failure, &[]);
 238                 } else {
 239                     fx.bcx.ins().brnz(cond, failure, &[]);
 240                 };
 241                 fx.bcx.ins().jump(target, &[]);
 242
 243                 fx.bcx.switch_to_block(failure);
 244                 trap_panic(
 245                     fx,
 246                     format!(
 247                         "[panic] Assert {:?} at {:?} failed.",
 248                         msg,
 249                         bb_data.terminator().source_info.span
 250                     ),
 251                 );
 252             }
 253
 254             TerminatorKind::SwitchInt {
 255                 discr,
 256                 switch_ty: _,
 257                 values,
 258                 targets,
 259             } => {
 260                 let discr = trans_operand(fx, discr).load_scalar(fx);
 261                 let mut switch = ::cranelift_frontend::Switch::new();
 262                 for (i, value) in values.iter().enumerate() {
 263                     let block = fx.get_block(targets[i]);
 264                     switch.set_entry(*value as u64, block);
 265                 }
 266                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 267                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 268             }
 269             TerminatorKind::Call {
 270                 func,
 271                 args,
 272                 destination,
 273                 cleanup: _,
 274                 from_hir_call: _,
 275             } => {
 276                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 277                     fx,
 278                     bb_data.terminator().source_info.span,
 279                     func,
 280                     args,
 281                     *destination,
 282                 ));
 283             }
 284             TerminatorKind::Resume | TerminatorKind::Abort => {
 285                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 286             }
 287             TerminatorKind::Unreachable => {
 288                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 289             }
 290             TerminatorKind::Yield { .. }
 291             | TerminatorKind::FalseEdges { .. }
 292             | TerminatorKind::FalseUnwind { .. }
 293             | TerminatorKind::DropAndReplace { .. }
 294             | TerminatorKind::GeneratorDrop => {
 295                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 296             }
 297             TerminatorKind::Drop {
 298                 location,
 299                 target,
 300                 unwind: _,
 301             } => {
 302                 let drop_place = trans_place(fx, *location);
 303                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 304
 305                 let target_block = fx.get_block(*target);
 306                 fx.bcx.ins().jump(target_block, &[]);
 307             }
 308         };
 309     }
 310
 311     fx.bcx.seal_all_blocks();
 312     fx.bcx.finalize();
 313 }
 314
 315 fn trans_stmt<'tcx>(
 316     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 317     #[allow(unused_variables)]
 318     cur_block: Block,
 319     stmt: &Statement<'tcx>,
 320 ) {
 321     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 322
 323     fx.set_debug_loc(stmt.source_info);
 324
 325     #[cfg(false_debug_assertions)]
 326     match &stmt.kind {
 327         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 328         _ => {
 329             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 330             fx.add_comment(inst, format!("{:?}", stmt));
 331         }
 332     }
 333
 334     match &stmt.kind {
 335         StatementKind::SetDiscriminant {
 336             place,
 337             variant_index,
 338         } => {
 339             let place = trans_place(fx, **place);
 340             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 341         }
 342         StatementKind::Assign(to_place_and_rval) => {
 343             let lval = trans_place(fx, to_place_and_rval.0);
 344             let dest_layout = lval.layout();
 345             match &to_place_and_rval.1 {
 346                 Rvalue::Use(operand) => {
 347                     let val = trans_operand(fx, operand);
 348                     lval.write_cvalue(fx, val);
 349                 }
 350                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 351                     let place = trans_place(fx, *place);
 352                     place.write_place_ref(fx, lval);
 353                 }
 354                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 355                     let lhs = trans_operand(fx, lhs);
 356                     let rhs = trans_operand(fx, rhs);
 357
 358                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 359                     lval.write_cvalue(fx, res);
 360                 }
 361                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 362                     let lhs = trans_operand(fx, lhs);
 363                     let rhs = trans_operand(fx, rhs);
 364
 365                     let res = if !fx.tcx.sess.overflow_checks() {
 366                         let val =
 367                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 368                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 369                         CValue::by_val_pair(val, is_overflow, lval.layout())
 370                     } else {
 371                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 372                     };
 373
 374                     lval.write_cvalue(fx, res);
 375                 }
 376                 Rvalue::UnaryOp(un_op, operand) => {
 377                     let operand = trans_operand(fx, operand);
 378                     let layout = operand.layout();
 379                     let val = operand.load_scalar(fx);
 380                     let res = match un_op {
 381                         UnOp::Not => {
 382                             match layout.ty.kind {
 383                                 ty::Bool => {
 384                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 385                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 386                                 }
 387                                 ty::Uint(_) | ty::Int(_) => {
 388                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 389                                 }
 390                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 391                             }
 392                         }
 393                         UnOp::Neg => match layout.ty.kind {
 394                             ty::Int(IntTy::I128) => {
 395                                 // FIXME remove this case once ineg.i128 works
 396                                 let zero = CValue::const_val(fx, layout, 0);
 397                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 398                             }
 399                             ty::Int(_) => {
 400                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 401                             }
 402                             ty::Float(_) => {
 403                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 404                             }
 405                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 406                         },
 407                     };
 408                     lval.write_cvalue(fx, res);
 409                 }
 410                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 411                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 412                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 413                     match from_ty.kind {
 414                         ty::FnDef(def_id, substs) => {
 415                             let func_ref = fx.get_function_ref(
 416                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 417                                     .unwrap(),
 418                             );
 419                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 420                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 421                         }
 422                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 423                     }
 424                 }
 425                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 426                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 427                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 428                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 429                     let operand = trans_operand(fx, operand);
 430                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 431                 }
 432                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 433                     let operand = trans_operand(fx, operand);
 434                     let from_ty = operand.layout().ty;
 435                     let to_ty = fx.monomorphize(to_ty);
 436
 437                     fn is_fat_ptr<'tcx>(
 438                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 439                         ty: Ty<'tcx>,
 440                     ) -> bool {
 441                         ty.builtin_deref(true)
 442                             .map(
 443                                 |ty::TypeAndMut {
 444                                      ty: pointee_ty,
 445                                      mutbl: _,
 446                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 447                             )
 448                             .unwrap_or(false)
 449                     }
 450
 451                     if is_fat_ptr(fx, from_ty) {
 452                         if is_fat_ptr(fx, to_ty) {
 453                             // fat-ptr -> fat-ptr
 454                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 455                         } else {
 456                             // fat-ptr -> thin-ptr
 457                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 458                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 459                         }
 460                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 461                         // enum -> discriminant value
 462                         assert!(adt_def.is_enum());
 463                         match to_ty.kind {
 464                             ty::Uint(_) | ty::Int(_) => {}
 465                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 466                         }
 467
 468                         let discr = crate::discriminant::codegen_get_discriminant(
 469                             fx,
 470                             operand,
 471                             fx.layout_of(to_ty),
 472                         );
 473                         lval.write_cvalue(fx, discr);
 474                     } else {
 475                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 476                         let from = operand.load_scalar(fx);
 477
 478                         let res = clif_int_or_float_cast(
 479                             fx,
 480                             from,
 481                             type_sign(from_ty),
 482                             to_clif_ty,
 483                             type_sign(to_ty),
 484                         );
 485                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 486                     }
 487                 }
 488                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 489                     let operand = trans_operand(fx, operand);
 490                     match operand.layout().ty.kind {
 491                         ty::Closure(def_id, substs) => {
 492                             let instance = Instance::resolve_closure(
 493                                 fx.tcx,
 494                                 def_id,
 495                                 substs,
 496                                 ty::ClosureKind::FnOnce,
 497                             );
 498                             let func_ref = fx.get_function_ref(instance);
 499                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 500                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 501                         }
 502                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 503                     }
 504                 }
 505                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 506                     let operand = trans_operand(fx, operand);
 507                     operand.unsize_value(fx, lval);
 508                 }
 509                 Rvalue::Discriminant(place) => {
 510                     let place = trans_place(fx, *place);
 511                     let value = place.to_cvalue(fx);
 512                     let discr =
 513                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 514                     lval.write_cvalue(fx, discr);
 515                 }
 516                 Rvalue::Repeat(operand, times) => {
 517                     let operand = trans_operand(fx, operand);
 518                     let times = fx
 519                         .monomorphize(times)
 520                         .eval(fx.tcx, ParamEnv::reveal_all())
 521                         .val
 522                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 523                         .unwrap();
 524                     for i in 0..times {
 525                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 526                         let to = lval.place_index(fx, index);
 527                         to.write_cvalue(fx, operand);
 528                     }
 529                 }
 530                 Rvalue::Len(place) => {
 531                     let place = trans_place(fx, *place);
 532                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 533                     let len = codegen_array_len(fx, place);
 534                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 535                 }
 536                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 537                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 538
 539                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 540                     let content_ty = fx.monomorphize(content_ty);
 541                     let layout = fx.layout_of(content_ty);
 542                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 543                     let llalign = fx
 544                         .bcx
 545                         .ins()
 546                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 547                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 548
 549                     // Allocate space:
 550                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 551                         Ok(id) => id,
 552                         Err(s) => {
 553                             fx.tcx
 554                                 .sess
 555                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 556                         }
 557                     };
 558                     let instance = ty::Instance::mono(fx.tcx, def_id);
 559                     let func_ref = fx.get_function_ref(instance);
 560                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 561                     let ptr = fx.bcx.inst_results(call)[0];
 562                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 563                 }
 564                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 565                     assert!(lval
 566                         .layout()
 567                         .ty
 568                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 569                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 570                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 571                     lval.write_cvalue(fx, val);
 572                 }
 573                 Rvalue::Aggregate(kind, operands) => match **kind {
 574                     AggregateKind::Array(_ty) => {
 575                         for (i, operand) in operands.into_iter().enumerate() {
 576                             let operand = trans_operand(fx, operand);
 577                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 578                             let to = lval.place_index(fx, index);
 579                             to.write_cvalue(fx, operand);
 580                         }
 581                     }
 582                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 583                 },
 584             }
 585         }
 586         StatementKind::StorageLive(_)
 587         | StatementKind::StorageDead(_)
 588         | StatementKind::Nop
 589         | StatementKind::FakeRead(..)
 590         | StatementKind::Retag { .. }
 591         | StatementKind::AscribeUserType(..) => {}
 592
 593         StatementKind::LlvmInlineAsm(asm) => {
 594             use rustc_ast::ast::Name;
 595             let LlvmInlineAsm {
 596                 asm,
 597                 outputs: _,
 598                 inputs: _,
 599             } = &**asm;
 600             let rustc_hir::LlvmInlineAsmInner {
 601                 asm: asm_code, // Name
 602                 outputs,       // Vec<Name>
 603                 inputs,        // Vec<Name>
 604                 clobbers,      // Vec<Name>
 605                 volatile,      // bool
 606                 alignstack,    // bool
 607                 dialect: _,    // rustc_ast::ast::AsmDialect
 608                 asm_str_style: _,
 609             } = asm;
 610             match &*asm_code.as_str() {
 611                 "" => {
 612                     assert_eq!(inputs, &[Name::intern("r")]);
 613                     assert!(outputs.is_empty(), "{:?}", outputs);
 614
 615                     // Black box
 616                 }
 617                 "cpuid" | "cpuid\n" => {
 618                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 619
 620                     assert_eq!(outputs.len(), 4);
 621                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 622                         .iter()
 623                         .enumerate()
 624                     {
 625                         assert_eq!(&outputs[i].constraint.as_str(), c);
 626                         assert!(!outputs[i].is_rw);
 627                         assert!(!outputs[i].is_indirect);
 628                     }
 629
 630                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 631
 632                     assert!(!volatile);
 633                     assert!(!alignstack);
 634
 635                     crate::trap::trap_unimplemented(
 636                         fx,
 637                         "__cpuid_count arch intrinsic is not supported",
 638                     );
 639                 }
 640                 "xgetbv" => {
 641                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 642
 643                     assert_eq!(outputs.len(), 2);
 644                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 645                         assert_eq!(&outputs[i].constraint.as_str(), c);
 646                         assert!(!outputs[i].is_rw);
 647                         assert!(!outputs[i].is_indirect);
 648                     }
 649
 650                     assert_eq!(clobbers, &[]);
 651
 652                     assert!(!volatile);
 653                     assert!(!alignstack);
 654
 655                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 656                 }
 657                 _ => unimpl_fatal!(fx.tcx, stmt.source_info.span, "Inline assembly is not supported"),
 658             }
 659         }
 660     }
 661 }
 662
 663 fn codegen_array_len<'tcx>(
 664     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 665     place: CPlace<'tcx>,
 666 ) -> Value {
 667     match place.layout().ty.kind {
 668         ty::Array(_elem_ty, len) => {
 669             let len = fx.monomorphize(&len)
 670                 .eval(fx.tcx, ParamEnv::reveal_all())
 671                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 672             fx.bcx.ins().iconst(fx.pointer_type, len)
 673         }
 674         ty::Slice(_elem_ty) => place
 675             .to_ptr_maybe_unsized()
 676             .1
 677             .expect("Length metadata for slice place"),
 678         _ => bug!("Rvalue::Len({:?})", place),
 679     }
 680 }
 681
 682 pub(crate) fn trans_place<'tcx>(
 683     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 684     place: Place<'tcx>,
 685 ) -> CPlace<'tcx> {
 686     let mut cplace = fx.get_local_place(place.local);
 687
 688     for elem in place.projection {
 689         match *elem {
 690             PlaceElem::Deref => {
 691                 cplace = cplace.place_deref(fx);
 692             }
 693             PlaceElem::Field(field, _ty) => {
 694                 cplace = cplace.place_field(fx, field);
 695             }
 696             PlaceElem::Index(local) => {
 697                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 698                 cplace = cplace.place_index(fx, index);
 699             }
 700             PlaceElem::ConstantIndex {
 701                 offset,
 702                 min_length: _,
 703                 from_end,
 704             } => {
 705                 let index = if !from_end {
 706                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 707                 } else {
 708                     let len = codegen_array_len(fx, cplace);
 709                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 710                 };
 711                 cplace = cplace.place_index(fx, index);
 712             }
 713             PlaceElem::Subslice { from, to, from_end } => {
 714                 // These indices are generated by slice patterns.
 715                 // slice[from:-to] in Python terms.
 716
 717                 match cplace.layout().ty.kind {
 718                     ty::Array(elem_ty, _len) => {
 719                         assert!(!from_end, "array subslices are never `from_end`");
 720                         let elem_layout = fx.layout_of(elem_ty);
 721                         let ptr = cplace.to_ptr();
 722                         cplace = CPlace::for_ptr(
 723                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 724                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 725                         );
 726                     }
 727                     ty::Slice(elem_ty) => {
 728                         assert!(from_end, "slice subslices should be `from_end`");
 729                         let elem_layout = fx.layout_of(elem_ty);
 730                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 731                         let len = len.unwrap();
 732                         cplace = CPlace::for_ptr_with_extra(
 733                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 734                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 735                             cplace.layout(),
 736                         );
 737                     }
 738                     _ => unreachable!(),
 739                 }
 740             }
 741             PlaceElem::Downcast(_adt_def, variant) => {
 742                 cplace = cplace.downcast_variant(fx, variant);
 743             }
 744         }
 745     }
 746
 747     cplace
 748 }
 749
 750 pub(crate) fn trans_operand<'tcx>(
 751     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 752     operand: &Operand<'tcx>,
 753 ) -> CValue<'tcx> {
 754     match operand {
 755         Operand::Move(place) | Operand::Copy(place) => {
 756             let cplace = trans_place(fx, *place);
 757             cplace.to_cvalue(fx)
 758         }
 759         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 760     }
 761 }