src/base.rs

   1 use rustc_middle::ty::adjustment::PointerCast;
   2 use rustc_index::vec::IndexVec;
   3
   4 use crate::prelude::*;
   5
   6 pub(crate) fn trans_fn<'tcx, B: Backend + 'static>(
   7     cx: &mut crate::CodegenCx<'tcx, B>,
   8     instance: Instance<'tcx>,
   9     linkage: Linkage,
  10 ) {
  11     let tcx = cx.tcx;
  12
  13     let mir = tcx.instance_mir(instance.def);
  14
  15     // Declare function
  16     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  17     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  18
  19     // Make FunctionBuilder
  20     let context = &mut cx.cached_context;
  21     context.clear();
  22     context.func.name = ExternalName::user(0, func_id.as_u32());
  23     context.func.signature = sig;
  24     context.func.collect_debug_info();
  25     let mut func_ctx = FunctionBuilderContext::new();
  26     let mut bcx = FunctionBuilder::new(&mut context.func, &mut func_ctx);
  27
  28     // Predefine blocks
  29     let start_block = bcx.create_block();
  30     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  31
  32     // Make FunctionCx
  33     let pointer_type = cx.module.target_config().pointer_type();
  34     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  35
  36     let mut fx = FunctionCx {
  37         tcx,
  38         module: &mut cx.module,
  39         global_asm: &mut cx.global_asm,
  40         pointer_type,
  41
  42         instance,
  43         mir,
  44
  45         bcx,
  46         block_map,
  47         local_map: FxHashMap::with_capacity_and_hasher(mir.local_decls.len(), Default::default()),
  48         caller_location: None, // set by `codegen_fn_prelude`
  49         cold_blocks: EntitySet::new(),
  50
  51         clif_comments,
  52         constants_cx: &mut cx.constants_cx,
  53         vtables: &mut cx.vtables,
  54         source_info_set: indexmap::IndexSet::new(),
  55         next_ssa_var: 0,
  56     };
  57
  58     let arg_uninhabited = fx.mir.args_iter().any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  59
  60     if arg_uninhabited {
  61         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  62         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  63         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  64     } else {
  65         tcx.sess.time("codegen clif ir", || {
  66             tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
  67             codegen_fn_content(&mut fx);
  68         });
  69     }
  70
  71     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  72     let instance = fx.instance;
  73     let mut clif_comments = fx.clif_comments;
  74     let source_info_set = fx.source_info_set;
  75     let local_map = fx.local_map;
  76     let cold_blocks = fx.cold_blocks;
  77
  78     crate::pretty_clif::write_clif_file(
  79         cx.tcx,
  80         "unopt",
  81         None,
  82         instance,
  83         &context,
  84         &clif_comments,
  85     );
  86
  87     // Verify function
  88     verify_func(tcx, &clif_comments, &context.func);
  89
  90     // Perform rust specific optimizations
  91     tcx.sess.time("optimize clif ir", || {
  92         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
  93     });
  94
  95     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
  96     // instruction, which doesn't have an encoding.
  97     context.compute_cfg();
  98     context.compute_domtree();
  99     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 100
 101     // Define function
 102     let module = &mut cx.module;
 103     tcx.sess.time(
 104         "define function",
 105         || module.define_function(
 106             func_id,
 107             context,
 108             &mut cranelift_codegen::binemit::NullTrapSink {},
 109         ).unwrap(),
 110     );
 111
 112     // Write optimized function to file for debugging
 113     crate::pretty_clif::write_clif_file(
 114         cx.tcx,
 115         "opt",
 116         Some(cx.module.isa()),
 117         instance,
 118         &context,
 119         &clif_comments,
 120     );
 121
 122     // Define debuginfo for function
 123     let isa = cx.module.isa();
 124     let debug_context = &mut cx.debug_context;
 125     let unwind_context = &mut cx.unwind_context;
 126     tcx.sess.time("generate debug info", || {
 127         if let Some(debug_context) = debug_context {
 128             debug_context.define_function(instance, func_id, &name, isa, context, &source_info_set, local_map);
 129         }
 130         unwind_context.add_function(func_id, &context, isa);
 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 = cranelift_codegen::settings::Flags::new(cranelift_codegen::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
 245                 let location = fx.get_caller_location(bb_data.terminator().source_info.span).load_scalar(fx);
 246
 247                 let args;
 248                 let lang_item = match msg {
 249                     AssertKind::BoundsCheck { ref len, ref index } => {
 250                         let len = trans_operand(fx, len).load_scalar(fx);
 251                         let index = trans_operand(fx, index).load_scalar(fx);
 252                         args = [index, len, location];
 253                         rustc_hir::lang_items::PanicBoundsCheckFnLangItem
 254                     }
 255                     _ => {
 256                         let msg_str = msg.description();
 257                         let msg_ptr = fx.anonymous_str("assert", msg_str);
 258                         let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 259                         args = [msg_ptr, msg_len, location];
 260                         rustc_hir::lang_items::PanicFnLangItem
 261                     }
 262                 };
 263
 264                 let def_id = fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| {
 265                     fx.tcx.sess.span_fatal(bb_data.terminator().source_info.span, &s)
 266                 });
 267
 268                 let instance = Instance::mono(fx.tcx, def_id);
 269                 let symbol_name = fx.tcx.symbol_name(instance).name.as_str();
 270
 271                 fx.lib_call(&*symbol_name, vec![fx.pointer_type, fx.pointer_type, fx.pointer_type], vec![], &args);
 272
 273                 crate::trap::trap_unreachable(fx, "panic lang item returned");
 274             }
 275
 276             TerminatorKind::SwitchInt {
 277                 discr,
 278                 switch_ty: _,
 279                 values,
 280                 targets,
 281             } => {
 282                 let discr = trans_operand(fx, discr).load_scalar(fx);
 283                 let mut switch = ::cranelift_frontend::Switch::new();
 284                 for (i, value) in values.iter().enumerate() {
 285                     let block = fx.get_block(targets[i]);
 286                     switch.set_entry((*value).try_into().unwrap(), block);
 287                 }
 288                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 289                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 290             }
 291             TerminatorKind::Call {
 292                 func,
 293                 args,
 294                 destination,
 295                 fn_span,
 296                 cleanup: _,
 297                 from_hir_call: _,
 298             } => {
 299                 fx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 300                     fx,
 301                     *fn_span,
 302                     block,
 303                     func,
 304                     args,
 305                     *destination,
 306                 ));
 307             }
 308             TerminatorKind::InlineAsm {
 309                 template,
 310                 operands,
 311                 options,
 312                 destination,
 313                 line_spans: _,
 314             } => {
 315                 crate::inline_asm::codegen_inline_asm(
 316                     fx,
 317                     bb_data.terminator().source_info.span,
 318                     template,
 319                     operands,
 320                     *options,
 321                 );
 322
 323                 match *destination {
 324                     Some(destination) => {
 325                         let destination_block = fx.get_block(destination);
 326                         fx.bcx.ins().jump(destination_block, &[]);
 327                     }
 328                     None => {
 329                         crate::trap::trap_unreachable(fx, "[corruption] Returned from noreturn inline asm");
 330                     }
 331                 }
 332             }
 333             TerminatorKind::Resume | TerminatorKind::Abort => {
 334                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 335             }
 336             TerminatorKind::Unreachable => {
 337                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 338             }
 339             TerminatorKind::Yield { .. }
 340             | TerminatorKind::FalseEdge { .. }
 341             | TerminatorKind::FalseUnwind { .. }
 342             | TerminatorKind::DropAndReplace { .. }
 343             | TerminatorKind::GeneratorDrop => {
 344                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 345             }
 346             TerminatorKind::Drop {
 347                 place,
 348                 target,
 349                 unwind: _,
 350             } => {
 351                 let drop_place = trans_place(fx, *place);
 352                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 353
 354                 let target_block = fx.get_block(*target);
 355                 fx.bcx.ins().jump(target_block, &[]);
 356             }
 357         };
 358     }
 359
 360     fx.bcx.seal_all_blocks();
 361     fx.bcx.finalize();
 362 }
 363
 364 fn trans_stmt<'tcx>(
 365     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 366     #[allow(unused_variables)]
 367     cur_block: Block,
 368     stmt: &Statement<'tcx>,
 369 ) {
 370     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 371
 372     fx.set_debug_loc(stmt.source_info);
 373
 374     #[cfg(false_debug_assertions)]
 375     match &stmt.kind {
 376         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 377         _ => {
 378             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 379             fx.add_comment(inst, format!("{:?}", stmt));
 380         }
 381     }
 382
 383     match &stmt.kind {
 384         StatementKind::SetDiscriminant {
 385             place,
 386             variant_index,
 387         } => {
 388             let place = trans_place(fx, **place);
 389             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 390         }
 391         StatementKind::Assign(to_place_and_rval) => {
 392             let lval = trans_place(fx, to_place_and_rval.0);
 393             let dest_layout = lval.layout();
 394             match &to_place_and_rval.1 {
 395                 Rvalue::Use(operand) => {
 396                     let val = trans_operand(fx, operand);
 397                     lval.write_cvalue(fx, val);
 398                 }
 399                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 400                     let place = trans_place(fx, *place);
 401                     place.write_place_ref(fx, lval);
 402                 }
 403                 Rvalue::ThreadLocalRef(def_id) => {
 404                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 405                     lval.write_cvalue(fx, val);
 406                 }
 407                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 408                     let lhs = trans_operand(fx, lhs);
 409                     let rhs = trans_operand(fx, rhs);
 410
 411                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 412                     lval.write_cvalue(fx, res);
 413                 }
 414                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 415                     let lhs = trans_operand(fx, lhs);
 416                     let rhs = trans_operand(fx, rhs);
 417
 418                     let res = if !fx.tcx.sess.overflow_checks() {
 419                         let val =
 420                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 421                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 422                         CValue::by_val_pair(val, is_overflow, lval.layout())
 423                     } else {
 424                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 425                     };
 426
 427                     lval.write_cvalue(fx, res);
 428                 }
 429                 Rvalue::UnaryOp(un_op, operand) => {
 430                     let operand = trans_operand(fx, operand);
 431                     let layout = operand.layout();
 432                     let val = operand.load_scalar(fx);
 433                     let res = match un_op {
 434                         UnOp::Not => {
 435                             match layout.ty.kind {
 436                                 ty::Bool => {
 437                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 438                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 439                                 }
 440                                 ty::Uint(_) | ty::Int(_) => {
 441                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 442                                 }
 443                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 444                             }
 445                         }
 446                         UnOp::Neg => match layout.ty.kind {
 447                             ty::Int(IntTy::I128) => {
 448                                 // FIXME remove this case once ineg.i128 works
 449                                 let zero = CValue::const_val(fx, layout, 0);
 450                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 451                             }
 452                             ty::Int(_) => {
 453                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 454                             }
 455                             ty::Float(_) => {
 456                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 457                             }
 458                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 459                         },
 460                     };
 461                     lval.write_cvalue(fx, res);
 462                 }
 463                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 464                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 465                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 466                     match from_ty.kind {
 467                         ty::FnDef(def_id, substs) => {
 468                             let func_ref = fx.get_function_ref(
 469                                 Instance::resolve_for_fn_ptr(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 470                                     .unwrap(),
 471                             );
 472                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 473                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 474                         }
 475                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 476                     }
 477                 }
 478                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 479                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 480                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 481                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 482                     let operand = trans_operand(fx, operand);
 483                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 484                 }
 485                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 486                     let operand = trans_operand(fx, operand);
 487                     let from_ty = operand.layout().ty;
 488                     let to_ty = fx.monomorphize(to_ty);
 489
 490                     fn is_fat_ptr<'tcx>(
 491                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 492                         ty: Ty<'tcx>,
 493                     ) -> bool {
 494                         ty.builtin_deref(true)
 495                             .map(
 496                                 |ty::TypeAndMut {
 497                                      ty: pointee_ty,
 498                                      mutbl: _,
 499                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 500                             )
 501                             .unwrap_or(false)
 502                     }
 503
 504                     if is_fat_ptr(fx, from_ty) {
 505                         if is_fat_ptr(fx, to_ty) {
 506                             // fat-ptr -> fat-ptr
 507                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 508                         } else {
 509                             // fat-ptr -> thin-ptr
 510                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 511                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 512                         }
 513                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 514                         // enum -> discriminant value
 515                         assert!(adt_def.is_enum());
 516                         match to_ty.kind {
 517                             ty::Uint(_) | ty::Int(_) => {}
 518                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 519                         }
 520
 521                         use rustc_target::abi::{TagEncoding, Int, Variants};
 522
 523                         match &operand.layout().variants {
 524                             Variants::Single { index } => {
 525                                 let discr = operand.layout().ty.discriminant_for_variant(fx.tcx, *index).unwrap();
 526                                 let discr = if discr.ty.is_signed() {
 527                                     rustc_middle::mir::interpret::sign_extend(discr.val, fx.layout_of(discr.ty).size)
 528                                 } else {
 529                                     discr.val
 530                                 };
 531
 532                                 let discr = CValue::const_val(fx, fx.layout_of(to_ty), discr);
 533                                 lval.write_cvalue(fx, discr);
 534                             }
 535                             Variants::Multiple {
 536                                 tag,
 537                                 tag_field,
 538                                 tag_encoding: TagEncoding::Direct,
 539                                 variants: _,
 540                             } => {
 541                                 let cast_to = fx.clif_type(dest_layout.ty).unwrap();
 542
 543                                 // Read the tag/niche-encoded discriminant from memory.
 544                                 let encoded_discr = operand.value_field(fx, mir::Field::new(*tag_field));
 545                                 let encoded_discr = encoded_discr.load_scalar(fx);
 546
 547                                 // Decode the discriminant (specifically if it's niche-encoded).
 548                                 let signed = match tag.value {
 549                                     Int(_, signed) => signed,
 550                                     _ => false,
 551                                 };
 552                                 let val = clif_intcast(fx, encoded_discr, cast_to, signed);
 553                                 let val = CValue::by_val(val, dest_layout);
 554                                 lval.write_cvalue(fx, val);
 555                             }
 556                             Variants::Multiple { ..} => unreachable!(),
 557                         }
 558                     } else {
 559                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 560                         let from = operand.load_scalar(fx);
 561
 562                         let res = clif_int_or_float_cast(
 563                             fx,
 564                             from,
 565                             type_sign(from_ty),
 566                             to_clif_ty,
 567                             type_sign(to_ty),
 568                         );
 569                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 570                     }
 571                 }
 572                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 573                     let operand = trans_operand(fx, operand);
 574                     match operand.layout().ty.kind {
 575                         ty::Closure(def_id, substs) => {
 576                             let instance = Instance::resolve_closure(
 577                                 fx.tcx,
 578                                 def_id,
 579                                 substs,
 580                                 ty::ClosureKind::FnOnce,
 581                             );
 582                             let func_ref = fx.get_function_ref(instance);
 583                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 584                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 585                         }
 586                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 587                     }
 588                 }
 589                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 590                     let operand = trans_operand(fx, operand);
 591                     operand.unsize_value(fx, lval);
 592                 }
 593                 Rvalue::Discriminant(place) => {
 594                     let place = trans_place(fx, *place);
 595                     let value = place.to_cvalue(fx);
 596                     let discr =
 597                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 598                     lval.write_cvalue(fx, discr);
 599                 }
 600                 Rvalue::Repeat(operand, times) => {
 601                     let operand = trans_operand(fx, operand);
 602                     let times = fx
 603                         .monomorphize(times)
 604                         .eval(fx.tcx, ParamEnv::reveal_all())
 605                         .val
 606                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 607                         .unwrap();
 608                     for i in 0..times {
 609                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 610                         let to = lval.place_index(fx, index);
 611                         to.write_cvalue(fx, operand);
 612                     }
 613                 }
 614                 Rvalue::Len(place) => {
 615                     let place = trans_place(fx, *place);
 616                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 617                     let len = codegen_array_len(fx, place);
 618                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 619                 }
 620                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 621                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 622
 623                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 624                     let content_ty = fx.monomorphize(content_ty);
 625                     let layout = fx.layout_of(content_ty);
 626                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 627                     let llalign = fx
 628                         .bcx
 629                         .ins()
 630                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 631                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 632
 633                     // Allocate space:
 634                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 635                         Ok(id) => id,
 636                         Err(s) => {
 637                             fx.tcx
 638                                 .sess
 639                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 640                         }
 641                     };
 642                     let instance = ty::Instance::mono(fx.tcx, def_id);
 643                     let func_ref = fx.get_function_ref(instance);
 644                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 645                     let ptr = fx.bcx.inst_results(call)[0];
 646                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 647                 }
 648                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 649                     assert!(lval
 650                         .layout()
 651                         .ty
 652                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 653                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 654                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 655                     lval.write_cvalue(fx, val);
 656                 }
 657                 Rvalue::Aggregate(kind, operands) => match **kind {
 658                     AggregateKind::Array(_ty) => {
 659                         for (i, operand) in operands.into_iter().enumerate() {
 660                             let operand = trans_operand(fx, operand);
 661                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 662                             let to = lval.place_index(fx, index);
 663                             to.write_cvalue(fx, operand);
 664                         }
 665                     }
 666                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 667                 },
 668             }
 669         }
 670         StatementKind::StorageLive(_)
 671         | StatementKind::StorageDead(_)
 672         | StatementKind::Nop
 673         | StatementKind::FakeRead(..)
 674         | StatementKind::Retag { .. }
 675         | StatementKind::AscribeUserType(..) => {}
 676
 677         StatementKind::LlvmInlineAsm(asm) => {
 678             use rustc_span::symbol::Symbol;
 679             let LlvmInlineAsm {
 680                 asm,
 681                 outputs: _,
 682                 inputs: _,
 683             } = &**asm;
 684             let rustc_hir::LlvmInlineAsmInner {
 685                 asm: asm_code, // Name
 686                 outputs,       // Vec<Name>
 687                 inputs,        // Vec<Name>
 688                 clobbers,      // Vec<Name>
 689                 volatile,      // bool
 690                 alignstack,    // bool
 691                 dialect: _,    // rustc_ast::ast::AsmDialect
 692                 asm_str_style: _,
 693             } = asm;
 694             match &*asm_code.as_str() {
 695                 "" => {
 696                     // Black box
 697                 }
 698                 cpuid if cpuid.contains("cpuid") => {
 699                     crate::trap::trap_unimplemented(
 700                         fx,
 701                         "__cpuid_count arch intrinsic is not supported",
 702                     );
 703                 }
 704                 "xgetbv" => {
 705                     assert_eq!(inputs, &[Symbol::intern("{ecx}")]);
 706
 707                     assert_eq!(outputs.len(), 2);
 708                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 709                         assert_eq!(&outputs[i].constraint.as_str(), c);
 710                         assert!(!outputs[i].is_rw);
 711                         assert!(!outputs[i].is_indirect);
 712                     }
 713
 714                     assert_eq!(clobbers, &[]);
 715
 716                     assert!(!volatile);
 717                     assert!(!alignstack);
 718
 719                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 720                 }
 721                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 722                 _ if fx.tcx.symbol_name(fx.instance).name.as_str().starts_with("___chkstk") => {
 723                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 724                 }
 725                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__alloca" => {
 726                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 727                 }
 728                 // Used in sys::windows::abort_internal
 729                 "int $$0x29" => {
 730                     crate::trap::trap_unimplemented(fx, "Windows abort");
 731                 }
 732                 _ => fx.tcx.sess.span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 733             }
 734         }
 735     }
 736 }
 737
 738 fn codegen_array_len<'tcx>(
 739     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 740     place: CPlace<'tcx>,
 741 ) -> Value {
 742     match place.layout().ty.kind {
 743         ty::Array(_elem_ty, len) => {
 744             let len = fx.monomorphize(&len)
 745                 .eval(fx.tcx, ParamEnv::reveal_all())
 746                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 747             fx.bcx.ins().iconst(fx.pointer_type, len)
 748         }
 749         ty::Slice(_elem_ty) => place
 750             .to_ptr_maybe_unsized()
 751             .1
 752             .expect("Length metadata for slice place"),
 753         _ => bug!("Rvalue::Len({:?})", place),
 754     }
 755 }
 756
 757 pub(crate) fn trans_place<'tcx>(
 758     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 759     place: Place<'tcx>,
 760 ) -> CPlace<'tcx> {
 761     let mut cplace = fx.get_local_place(place.local);
 762
 763     for elem in place.projection {
 764         match elem {
 765             PlaceElem::Deref => {
 766                 cplace = cplace.place_deref(fx);
 767             }
 768             PlaceElem::Field(field, _ty) => {
 769                 cplace = cplace.place_field(fx, field);
 770             }
 771             PlaceElem::Index(local) => {
 772                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 773                 cplace = cplace.place_index(fx, index);
 774             }
 775             PlaceElem::ConstantIndex {
 776                 offset,
 777                 min_length: _,
 778                 from_end,
 779             } => {
 780                 let index = if !from_end {
 781                     fx.bcx.ins().iconst(fx.pointer_type, i64::from(offset))
 782                 } else {
 783                     let len = codegen_array_len(fx, cplace);
 784                     fx.bcx.ins().iadd_imm(len, -i64::from(offset))
 785                 };
 786                 cplace = cplace.place_index(fx, index);
 787             }
 788             PlaceElem::Subslice { from, to, from_end } => {
 789                 // These indices are generated by slice patterns.
 790                 // slice[from:-to] in Python terms.
 791
 792                 match cplace.layout().ty.kind {
 793                     ty::Array(elem_ty, _len) => {
 794                         assert!(!from_end, "array subslices are never `from_end`");
 795                         let elem_layout = fx.layout_of(elem_ty);
 796                         let ptr = cplace.to_ptr();
 797                         cplace = CPlace::for_ptr(
 798                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * i64::from(from)),
 799                             fx.layout_of(fx.tcx.mk_array(elem_ty, u64::from(to) - u64::from(from))),
 800                         );
 801                     }
 802                     ty::Slice(elem_ty) => {
 803                         assert!(from_end, "slice subslices should be `from_end`");
 804                         let elem_layout = fx.layout_of(elem_ty);
 805                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 806                         let len = len.unwrap();
 807                         cplace = CPlace::for_ptr_with_extra(
 808                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * i64::from(from)),
 809                             fx.bcx.ins().iadd_imm(len, -(i64::from(from) + i64::from(to))),
 810                             cplace.layout(),
 811                         );
 812                     }
 813                     _ => unreachable!(),
 814                 }
 815             }
 816             PlaceElem::Downcast(_adt_def, variant) => {
 817                 cplace = cplace.downcast_variant(fx, variant);
 818             }
 819         }
 820     }
 821
 822     cplace
 823 }
 824
 825 pub(crate) fn trans_operand<'tcx>(
 826     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 827     operand: &Operand<'tcx>,
 828 ) -> CValue<'tcx> {
 829     match operand {
 830         Operand::Move(place) | Operand::Copy(place) => {
 831             let cplace = trans_place(fx, *place);
 832             cplace.to_cvalue(fx)
 833         }
 834         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 835     }
 836 }