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 block's
  33     let start_block = bcx.create_block();
  34     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  35
  36     // Make FunctionCx
  37     let pointer_type = cx.module.target_config().pointer_type();
  38     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  39
  40     let mut fx = FunctionCx {
  41         tcx,
  42         module: cx.module,
  43         pointer_type,
  44
  45         instance,
  46         mir,
  47
  48         bcx,
  49         block_map,
  50         local_map: 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     let is_call_once_for_box = name.starts_with("_ZN83_$LT$alloc..boxed..Box$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once");
  62
  63     if arg_uninhabited {
  64         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  65         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  66         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  67     } else if is_call_once_for_box {
  68         // HACK implement `<Box<F> as FnOnce>::call_once` without `alloca`.
  69         tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, false));
  70         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  71         let bb_data = &fx.mir.basic_blocks()[START_BLOCK];
  72         let destination = match &bb_data.terminator().kind {
  73             TerminatorKind::Call {
  74                 func,
  75                 args,
  76                 destination,
  77                 cleanup: _,
  78                 from_hir_call: _,
  79             } => {
  80                 assert_eq!(args.len(), 2);
  81
  82                 let closure_arg = Local::new(1);
  83                 let closure_local = args[0].place().unwrap().as_local().unwrap();
  84                 assert_eq!(fx.mir.local_decls[closure_local].ty, fx.mir.local_decls[closure_arg].ty.builtin_deref(true).unwrap().ty);
  85                 let closure_deref = fx.local_map[&closure_arg].place_deref(&mut fx);
  86                 fx.local_map.insert(closure_local, closure_deref);
  87
  88                 let args_arg = Local::new(2);
  89                 let args_local = args[1].place().unwrap().as_local().unwrap();
  90                 assert_eq!(fx.mir.local_decls[args_local].ty, fx.mir.local_decls[args_arg].ty);
  91                 fx.local_map.insert(args_local, fx.local_map[&args_arg]);
  92
  93                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
  94                     &mut fx,
  95                     bb_data.terminator().source_info.span,
  96                     func,
  97                     args,
  98                     *destination,
  99                 ));
 100                 destination.map(|(_ret_place, ret_block)| ret_block)
 101             }
 102             _ => unreachable!(),
 103         };
 104
 105         let destination = if let Some(destination) = destination {
 106             fx.bcx.switch_to_block(fx.block_map[destination]);
 107             let bb_data = &fx.mir.basic_blocks()[destination];
 108             match &bb_data.terminator().kind {
 109                 TerminatorKind::Call {
 110                     func,
 111                     args,
 112                     destination,
 113                     cleanup: _,
 114                     from_hir_call: _,
 115                 } => {
 116                     match destination {
 117                         Some((ret_place, _ret_block)) => {
 118                             fx.local_map.insert(ret_place.as_local().unwrap(), CPlace::no_place(fx.layout_of(fx.tcx.mk_unit())));
 119                         }
 120                         None => {}
 121                     }
 122
 123                     assert_eq!(args.len(), 1);
 124                     fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 125                         &mut fx,
 126                         bb_data.terminator().source_info.span,
 127                         func,
 128                         args,
 129                         *destination,
 130                     ));
 131                     destination.map(|(_ret_place, ret_block)| ret_block)
 132                 }
 133                 _ => unreachable!(),
 134             }
 135         } else {
 136             None
 137         };
 138
 139         if let Some(destination) = destination {
 140             fx.bcx.switch_to_block(fx.block_map[destination]);
 141             let bb_data = &fx.mir.basic_blocks()[destination];
 142             match &bb_data.terminator().kind {
 143                 TerminatorKind::Return => crate::abi::codegen_return(&mut fx),
 144                 _ => unreachable!(),
 145             }
 146         }
 147     } else {
 148         tcx.sess.time("codegen clif ir", || {
 149             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block, true));
 150             codegen_fn_content(&mut fx);
 151         });
 152     }
 153
 154     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 155     let instance = fx.instance;
 156     let mut clif_comments = fx.clif_comments;
 157     let source_info_set = fx.source_info_set;
 158     let local_map = fx.local_map;
 159     let cold_blocks = fx.cold_blocks;
 160
 161     #[cfg(debug_assertions)]
 162     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
 163
 164     // Verify function
 165     verify_func(tcx, &clif_comments, &context.func);
 166
 167     // Perform rust specific optimizations
 168     tcx.sess.time("optimize clif ir", || {
 169         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
 170     });
 171
 172     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
 173     // instruction, which doesn't have an encoding.
 174     context.compute_cfg();
 175     context.compute_domtree();
 176     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 177
 178     // Define function
 179     let module = &mut cx.module;
 180     tcx.sess.time(
 181         "define function",
 182         || module.define_function(
 183             func_id,
 184             context,
 185             &mut cranelift_codegen::binemit::NullTrapSink {},
 186         ).unwrap(),
 187     );
 188
 189     // Write optimized function to file for debugging
 190     #[cfg(debug_assertions)]
 191     {
 192         let value_ranges = context
 193             .build_value_labels_ranges(cx.module.isa())
 194             .expect("value location ranges");
 195
 196         crate::pretty_clif::write_clif_file(
 197             cx.tcx,
 198             "opt",
 199             instance,
 200             &context.func,
 201             &clif_comments,
 202             Some(&value_ranges),
 203         );
 204     }
 205
 206     // Define debuginfo for function
 207     let isa = cx.module.isa();
 208     tcx.sess.time("generate debug info", || {
 209         debug_context
 210             .as_mut()
 211             .map(|x| x.define(context, isa, &source_info_set, local_map));
 212     });
 213
 214     // Clear context to make it usable for the next function
 215     context.clear();
 216 }
 217
 218 pub(crate) fn verify_func(tcx: TyCtxt<'_>, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 219     tcx.sess.time("verify clif ir", || {
 220         let flags = settings::Flags::new(settings::builder());
 221         match ::cranelift_codegen::verify_function(&func, &flags) {
 222             Ok(_) => {}
 223             Err(err) => {
 224                 tcx.sess.err(&format!("{:?}", err));
 225                 let pretty_error = ::cranelift_codegen::print_errors::pretty_verifier_error(
 226                     &func,
 227                     None,
 228                     Some(Box::new(writer)),
 229                     err,
 230                 );
 231                 tcx.sess
 232                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 233             }
 234         }
 235     });
 236 }
 237
 238 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 239     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 240         let block = fx.get_block(bb);
 241         fx.bcx.switch_to_block(block);
 242
 243         if bb_data.is_cleanup {
 244             // Unwinding after panicking is not supported
 245             continue;
 246
 247             // FIXME once unwinding is supported uncomment next lines
 248             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 249             // fx.cold_blocks.insert(block);
 250         }
 251
 252         fx.bcx.ins().nop();
 253         for stmt in &bb_data.statements {
 254             fx.set_debug_loc(stmt.source_info);
 255             trans_stmt(fx, block, stmt);
 256         }
 257
 258         #[cfg(debug_assertions)]
 259         {
 260             let mut terminator_head = "\n".to_string();
 261             bb_data
 262                 .terminator()
 263                 .kind
 264                 .fmt_head(&mut terminator_head)
 265                 .unwrap();
 266             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 267             fx.add_comment(inst, terminator_head);
 268         }
 269
 270         fx.set_debug_loc(bb_data.terminator().source_info);
 271
 272         match &bb_data.terminator().kind {
 273             TerminatorKind::Goto { target } => {
 274                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 275                     let mut can_immediately_return = true;
 276                     for stmt in &fx.mir[*target].statements {
 277                         if let StatementKind::StorageDead(_) = stmt.kind {
 278                         } else {
 279                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 280                             can_immediately_return = false;
 281                             break;
 282                         }
 283                     }
 284
 285                     if can_immediately_return {
 286                         crate::abi::codegen_return(fx);
 287                         continue;
 288                     }
 289                 }
 290
 291                 let block = fx.get_block(*target);
 292                 fx.bcx.ins().jump(block, &[]);
 293             }
 294             TerminatorKind::Return => {
 295                 crate::abi::codegen_return(fx);
 296             }
 297             TerminatorKind::Assert {
 298                 cond,
 299                 expected,
 300                 msg,
 301                 target,
 302                 cleanup: _,
 303             } => {
 304                 if !fx.tcx.sess.overflow_checks() {
 305                     if let mir::AssertKind::OverflowNeg = *msg {
 306                         let target = fx.get_block(*target);
 307                         fx.bcx.ins().jump(target, &[]);
 308                         continue;
 309                     }
 310                 }
 311                 let cond = trans_operand(fx, cond).load_scalar(fx);
 312
 313                 let target = fx.get_block(*target);
 314                 let failure = fx.bcx.create_block();
 315                 fx.cold_blocks.insert(failure);
 316
 317                 if *expected {
 318                     fx.bcx.ins().brz(cond, failure, &[]);
 319                 } else {
 320                     fx.bcx.ins().brnz(cond, failure, &[]);
 321                 };
 322                 fx.bcx.ins().jump(target, &[]);
 323
 324                 fx.bcx.switch_to_block(failure);
 325                 trap_panic(
 326                     fx,
 327                     format!(
 328                         "[panic] Assert {:?} at {:?} failed.",
 329                         msg,
 330                         bb_data.terminator().source_info.span
 331                     ),
 332                 );
 333             }
 334
 335             TerminatorKind::SwitchInt {
 336                 discr,
 337                 switch_ty: _,
 338                 values,
 339                 targets,
 340             } => {
 341                 let discr = trans_operand(fx, discr).load_scalar(fx);
 342                 let mut switch = ::cranelift_frontend::Switch::new();
 343                 for (i, value) in values.iter().enumerate() {
 344                     let block = fx.get_block(targets[i]);
 345                     switch.set_entry(*value as u64, block);
 346                 }
 347                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 348                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 349             }
 350             TerminatorKind::Call {
 351                 func,
 352                 args,
 353                 destination,
 354                 cleanup: _,
 355                 from_hir_call: _,
 356             } => {
 357                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 358                     fx,
 359                     bb_data.terminator().source_info.span,
 360                     func,
 361                     args,
 362                     *destination,
 363                 ));
 364             }
 365             TerminatorKind::Resume | TerminatorKind::Abort => {
 366                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 367             }
 368             TerminatorKind::Unreachable => {
 369                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 370             }
 371             TerminatorKind::Yield { .. }
 372             | TerminatorKind::FalseEdges { .. }
 373             | TerminatorKind::FalseUnwind { .. }
 374             | TerminatorKind::DropAndReplace { .. }
 375             | TerminatorKind::GeneratorDrop => {
 376                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 377             }
 378             TerminatorKind::Drop {
 379                 location,
 380                 target,
 381                 unwind: _,
 382             } => {
 383                 let drop_place = trans_place(fx, *location);
 384                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 385
 386                 let target_block = fx.get_block(*target);
 387                 fx.bcx.ins().jump(target_block, &[]);
 388             }
 389         };
 390     }
 391
 392     fx.bcx.seal_all_blocks();
 393     fx.bcx.finalize();
 394 }
 395
 396 fn trans_stmt<'tcx>(
 397     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 398     #[allow(unused_variables)]
 399     cur_block: Block,
 400     stmt: &Statement<'tcx>,
 401 ) {
 402     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 403
 404     fx.set_debug_loc(stmt.source_info);
 405
 406     #[cfg(false_debug_assertions)]
 407     match &stmt.kind {
 408         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 409         _ => {
 410             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 411             fx.add_comment(inst, format!("{:?}", stmt));
 412         }
 413     }
 414
 415     match &stmt.kind {
 416         StatementKind::SetDiscriminant {
 417             place,
 418             variant_index,
 419         } => {
 420             let place = trans_place(fx, **place);
 421             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 422         }
 423         StatementKind::Assign(to_place_and_rval) => {
 424             let lval = trans_place(fx, to_place_and_rval.0);
 425             let dest_layout = lval.layout();
 426             match &to_place_and_rval.1 {
 427                 Rvalue::Use(operand) => {
 428                     let val = trans_operand(fx, operand);
 429                     lval.write_cvalue(fx, val);
 430                 }
 431                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 432                     let place = trans_place(fx, *place);
 433                     place.write_place_ref(fx, lval);
 434                 }
 435                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 436                     let lhs = trans_operand(fx, lhs);
 437                     let rhs = trans_operand(fx, rhs);
 438
 439                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 440                     lval.write_cvalue(fx, res);
 441                 }
 442                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 443                     let lhs = trans_operand(fx, lhs);
 444                     let rhs = trans_operand(fx, rhs);
 445
 446                     let res = if !fx.tcx.sess.overflow_checks() {
 447                         let val =
 448                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 449                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 450                         CValue::by_val_pair(val, is_overflow, lval.layout())
 451                     } else {
 452                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 453                     };
 454
 455                     lval.write_cvalue(fx, res);
 456                 }
 457                 Rvalue::UnaryOp(un_op, operand) => {
 458                     let operand = trans_operand(fx, operand);
 459                     let layout = operand.layout();
 460                     let val = operand.load_scalar(fx);
 461                     let res = match un_op {
 462                         UnOp::Not => {
 463                             match layout.ty.kind {
 464                                 ty::Bool => {
 465                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 466                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 467                                 }
 468                                 ty::Uint(_) | ty::Int(_) => {
 469                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 470                                 }
 471                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 472                             }
 473                         }
 474                         UnOp::Neg => match layout.ty.kind {
 475                             ty::Int(IntTy::I128) => {
 476                                 // FIXME remove this case once ineg.i128 works
 477                                 let zero = CValue::const_val(fx, layout, 0);
 478                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 479                             }
 480                             ty::Int(_) => {
 481                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 482                             }
 483                             ty::Float(_) => {
 484                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 485                             }
 486                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 487                         },
 488                     };
 489                     lval.write_cvalue(fx, res);
 490                 }
 491                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 492                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 493                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 494                     match from_ty.kind {
 495                         ty::FnDef(def_id, substs) => {
 496                             let func_ref = fx.get_function_ref(
 497                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 498                                     .unwrap(),
 499                             );
 500                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 501                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 502                         }
 503                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 504                     }
 505                 }
 506                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 507                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 508                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 509                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 510                     let operand = trans_operand(fx, operand);
 511                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 512                 }
 513                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 514                     let operand = trans_operand(fx, operand);
 515                     let from_ty = operand.layout().ty;
 516                     let to_ty = fx.monomorphize(to_ty);
 517
 518                     fn is_fat_ptr<'tcx>(
 519                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 520                         ty: Ty<'tcx>,
 521                     ) -> bool {
 522                         ty.builtin_deref(true)
 523                             .map(
 524                                 |ty::TypeAndMut {
 525                                      ty: pointee_ty,
 526                                      mutbl: _,
 527                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 528                             )
 529                             .unwrap_or(false)
 530                     }
 531
 532                     if is_fat_ptr(fx, from_ty) {
 533                         if is_fat_ptr(fx, to_ty) {
 534                             // fat-ptr -> fat-ptr
 535                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 536                         } else {
 537                             // fat-ptr -> thin-ptr
 538                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 539                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 540                         }
 541                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 542                         // enum -> discriminant value
 543                         assert!(adt_def.is_enum());
 544                         match to_ty.kind {
 545                             ty::Uint(_) | ty::Int(_) => {}
 546                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 547                         }
 548
 549                         let discr = crate::discriminant::codegen_get_discriminant(
 550                             fx,
 551                             operand,
 552                             fx.layout_of(to_ty),
 553                         );
 554                         lval.write_cvalue(fx, discr);
 555                     } else {
 556                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 557                         let from = operand.load_scalar(fx);
 558
 559                         let res = clif_int_or_float_cast(
 560                             fx,
 561                             from,
 562                             type_sign(from_ty),
 563                             to_clif_ty,
 564                             type_sign(to_ty),
 565                         );
 566                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 567                     }
 568                 }
 569                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 570                     let operand = trans_operand(fx, operand);
 571                     match operand.layout().ty.kind {
 572                         ty::Closure(def_id, substs) => {
 573                             let instance = Instance::resolve_closure(
 574                                 fx.tcx,
 575                                 def_id,
 576                                 substs,
 577                                 ty::ClosureKind::FnOnce,
 578                             );
 579                             let func_ref = fx.get_function_ref(instance);
 580                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 581                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 582                         }
 583                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 584                     }
 585                 }
 586                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 587                     let operand = trans_operand(fx, operand);
 588                     operand.unsize_value(fx, lval);
 589                 }
 590                 Rvalue::Discriminant(place) => {
 591                     let place = trans_place(fx, *place);
 592                     let value = place.to_cvalue(fx);
 593                     let discr =
 594                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 595                     lval.write_cvalue(fx, discr);
 596                 }
 597                 Rvalue::Repeat(operand, times) => {
 598                     let operand = trans_operand(fx, operand);
 599                     let times = fx
 600                         .monomorphize(times)
 601                         .eval(fx.tcx, ParamEnv::reveal_all())
 602                         .val
 603                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 604                         .unwrap();
 605                     for i in 0..times {
 606                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 607                         let to = lval.place_index(fx, index);
 608                         to.write_cvalue(fx, operand);
 609                     }
 610                 }
 611                 Rvalue::Len(place) => {
 612                     let place = trans_place(fx, *place);
 613                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 614                     let len = codegen_array_len(fx, place);
 615                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 616                 }
 617                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 618                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 619
 620                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 621                     let content_ty = fx.monomorphize(content_ty);
 622                     let layout = fx.layout_of(content_ty);
 623                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 624                     let llalign = fx
 625                         .bcx
 626                         .ins()
 627                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 628                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 629
 630                     // Allocate space:
 631                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 632                         Ok(id) => id,
 633                         Err(s) => {
 634                             fx.tcx
 635                                 .sess
 636                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 637                         }
 638                     };
 639                     let instance = ty::Instance::mono(fx.tcx, def_id);
 640                     let func_ref = fx.get_function_ref(instance);
 641                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 642                     let ptr = fx.bcx.inst_results(call)[0];
 643                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 644                 }
 645                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 646                     assert!(lval
 647                         .layout()
 648                         .ty
 649                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 650                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 651                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 652                     lval.write_cvalue(fx, val);
 653                 }
 654                 Rvalue::Aggregate(kind, operands) => match **kind {
 655                     AggregateKind::Array(_ty) => {
 656                         for (i, operand) in operands.into_iter().enumerate() {
 657                             let operand = trans_operand(fx, operand);
 658                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 659                             let to = lval.place_index(fx, index);
 660                             to.write_cvalue(fx, operand);
 661                         }
 662                     }
 663                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 664                 },
 665             }
 666         }
 667         StatementKind::StorageLive(_)
 668         | StatementKind::StorageDead(_)
 669         | StatementKind::Nop
 670         | StatementKind::FakeRead(..)
 671         | StatementKind::Retag { .. }
 672         | StatementKind::AscribeUserType(..) => {}
 673
 674         StatementKind::LlvmInlineAsm(asm) => {
 675             use rustc_ast::ast::Name;
 676             let LlvmInlineAsm {
 677                 asm,
 678                 outputs: _,
 679                 inputs: _,
 680             } = &**asm;
 681             let rustc_hir::LlvmInlineAsmInner {
 682                 asm: asm_code, // Name
 683                 outputs,       // Vec<Name>
 684                 inputs,        // Vec<Name>
 685                 clobbers,      // Vec<Name>
 686                 volatile,      // bool
 687                 alignstack,    // bool
 688                 dialect: _,    // rustc_ast::ast::AsmDialect
 689                 asm_str_style: _,
 690             } = asm;
 691             match &*asm_code.as_str() {
 692                 "" => {
 693                     assert_eq!(inputs, &[Name::intern("r")]);
 694                     assert!(outputs.is_empty(), "{:?}", outputs);
 695
 696                     // Black box
 697                 }
 698                 "cpuid" | "cpuid\n" => {
 699                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 700
 701                     assert_eq!(outputs.len(), 4);
 702                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 703                         .iter()
 704                         .enumerate()
 705                     {
 706                         assert_eq!(&outputs[i].constraint.as_str(), c);
 707                         assert!(!outputs[i].is_rw);
 708                         assert!(!outputs[i].is_indirect);
 709                     }
 710
 711                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 712
 713                     assert!(!volatile);
 714                     assert!(!alignstack);
 715
 716                     crate::trap::trap_unimplemented(
 717                         fx,
 718                         "__cpuid_count arch intrinsic is not supported",
 719                     );
 720                 }
 721                 "xgetbv" => {
 722                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 723
 724                     assert_eq!(outputs.len(), 2);
 725                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 726                         assert_eq!(&outputs[i].constraint.as_str(), c);
 727                         assert!(!outputs[i].is_rw);
 728                         assert!(!outputs[i].is_indirect);
 729                     }
 730
 731                     assert_eq!(clobbers, &[]);
 732
 733                     assert!(!volatile);
 734                     assert!(!alignstack);
 735
 736                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 737                 }
 738                 _ => unimpl_fatal!(fx.tcx, stmt.source_info.span, "Inline assembly is not supported"),
 739             }
 740         }
 741     }
 742 }
 743
 744 fn codegen_array_len<'tcx>(
 745     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 746     place: CPlace<'tcx>,
 747 ) -> Value {
 748     match place.layout().ty.kind {
 749         ty::Array(_elem_ty, len) => {
 750             let len = fx.monomorphize(&len)
 751                 .eval(fx.tcx, ParamEnv::reveal_all())
 752                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 753             fx.bcx.ins().iconst(fx.pointer_type, len)
 754         }
 755         ty::Slice(_elem_ty) => place
 756             .to_ptr_maybe_unsized()
 757             .1
 758             .expect("Length metadata for slice place"),
 759         _ => bug!("Rvalue::Len({:?})", place),
 760     }
 761 }
 762
 763 pub(crate) fn trans_place<'tcx>(
 764     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 765     place: Place<'tcx>,
 766 ) -> CPlace<'tcx> {
 767     let mut cplace = fx.get_local_place(place.local);
 768
 769     for elem in place.projection {
 770         match *elem {
 771             PlaceElem::Deref => {
 772                 cplace = cplace.place_deref(fx);
 773             }
 774             PlaceElem::Field(field, _ty) => {
 775                 cplace = cplace.place_field(fx, field);
 776             }
 777             PlaceElem::Index(local) => {
 778                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 779                 cplace = cplace.place_index(fx, index);
 780             }
 781             PlaceElem::ConstantIndex {
 782                 offset,
 783                 min_length: _,
 784                 from_end,
 785             } => {
 786                 let index = if !from_end {
 787                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 788                 } else {
 789                     let len = codegen_array_len(fx, cplace);
 790                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 791                 };
 792                 cplace = cplace.place_index(fx, index);
 793             }
 794             PlaceElem::Subslice { from, to, from_end } => {
 795                 // These indices are generated by slice patterns.
 796                 // slice[from:-to] in Python terms.
 797
 798                 match cplace.layout().ty.kind {
 799                     ty::Array(elem_ty, _len) => {
 800                         assert!(!from_end, "array subslices are never `from_end`");
 801                         let elem_layout = fx.layout_of(elem_ty);
 802                         let ptr = cplace.to_ptr();
 803                         cplace = CPlace::for_ptr(
 804                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 805                             fx.layout_of(fx.tcx.mk_array(elem_ty, to as u64 - from as u64)),
 806                         );
 807                     }
 808                     ty::Slice(elem_ty) => {
 809                         assert!(from_end, "slice subslices should be `from_end`");
 810                         let elem_layout = fx.layout_of(elem_ty);
 811                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 812                         let len = len.unwrap();
 813                         cplace = CPlace::for_ptr_with_extra(
 814                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * from as i64),
 815                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 816                             cplace.layout(),
 817                         );
 818                     }
 819                     _ => unreachable!(),
 820                 }
 821             }
 822             PlaceElem::Downcast(_adt_def, variant) => {
 823                 cplace = cplace.downcast_variant(fx, variant);
 824             }
 825         }
 826     }
 827
 828     cplace
 829 }
 830
 831 pub(crate) fn trans_operand<'tcx>(
 832     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 833     operand: &Operand<'tcx>,
 834 ) -> CValue<'tcx> {
 835     match operand {
 836         Operand::Move(place) | Operand::Copy(place) => {
 837             let cplace = trans_place(fx, *place);
 838             cplace.to_cvalue(fx)
 839         }
 840         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 841     }
 842 }