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 = cxcodegen_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         inline_asm_index: 0,
  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));
  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     crate::pretty_clif::write_clif_file(
  81         cxcodegen_cx.tcx,
  82         "unopt",
  83         None,
  84         instance,
  85         &context,
  86         &clif_comments,
  87     );
  88
  89     // Verify function
  90     verify_func(tcx, &clif_comments, &context.func);
  91
  92     // Perform rust specific optimizations
  93     tcx.sess.time("optimize clif ir", || {
  94         crate::optimize::optimize_function(tcx, instance, context, &cold_blocks, &mut clif_comments);
  95     });
  96
  97     // If the return block is not reachable, then the SSA builder may have inserted a `iconst.i128`
  98     // instruction, which doesn't have an encoding.
  99     context.compute_cfg();
 100     context.compute_domtree();
 101     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 102
 103     // Define function
 104     let module = &mut cx.module;
 105     tcx.sess.time(
 106         "define function",
 107         || module.define_function(
 108             func_id,
 109             context,
 110             &mut cranelift_codegen::binemit::NullTrapSink {},
 111         ).unwrap(),
 112     );
 113
 114     // Write optimized function to file for debugging
 115     crate::pretty_clif::write_clif_file(
 116         cxcodegen_cx.tcx,
 117         "opt",
 118         Some(cx.module.isa()),
 119         instance,
 120         &context,
 121         &clif_comments,
 122     );
 123
 124     // Define debuginfo for function
 125     let isa = cx.module.isa();
 126     let debug_context = &mut cx.debug_context;
 127     let unwind_context = &mut cx.unwind_context;
 128     tcx.sess.time("generate debug info", || {
 129         if let Some(debug_context) = debug_context {
 130             debug_context.define_function(instance, func_id, &name, isa, context, &source_info_set, local_map);
 131         }
 132         unwind_context.add_function(func_id, &context, isa);
 133     });
 134
 135     // Clear context to make it usable for the next function
 136     context.clear();
 137 }
 138
 139 pub(crate) fn verify_func(tcx: TyCtxt<'_>, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 140     tcx.sess.time("verify clif ir", || {
 141         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 142         match cranelift_codegen::verify_function(&func, &flags) {
 143             Ok(_) => {}
 144             Err(err) => {
 145                 tcx.sess.err(&format!("{:?}", err));
 146                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 147                     &func,
 148                     None,
 149                     Some(Box::new(writer)),
 150                     err,
 151                 );
 152                 tcx.sess
 153                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 154             }
 155         }
 156     });
 157 }
 158
 159 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 160     crate::constant::check_constants(fx);
 161
 162     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 163         let block = fx.get_block(bb);
 164         fx.bcx.switch_to_block(block);
 165
 166         if bb_data.is_cleanup {
 167             // Unwinding after panicking is not supported
 168             continue;
 169
 170             // FIXME once unwinding is supported uncomment next lines
 171             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 172             // fx.cold_blocks.insert(block);
 173         }
 174
 175         fx.bcx.ins().nop();
 176         for stmt in &bb_data.statements {
 177             fx.set_debug_loc(stmt.source_info);
 178             trans_stmt(fx, block, stmt);
 179         }
 180
 181         #[cfg(debug_assertions)]
 182         {
 183             let mut terminator_head = "\n".to_string();
 184             bb_data
 185                 .terminator()
 186                 .kind
 187                 .fmt_head(&mut terminator_head)
 188                 .unwrap();
 189             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 190             fx.add_comment(inst, terminator_head);
 191         }
 192
 193         fx.set_debug_loc(bb_data.terminator().source_info);
 194
 195         match &bb_data.terminator().kind {
 196             TerminatorKind::Goto { target } => {
 197                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 198                     let mut can_immediately_return = true;
 199                     for stmt in &fx.mir[*target].statements {
 200                         if let StatementKind::StorageDead(_) = stmt.kind {
 201                         } else {
 202                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 203                             can_immediately_return = false;
 204                             break;
 205                         }
 206                     }
 207
 208                     if can_immediately_return {
 209                         crate::abi::codegen_return(fx);
 210                         continue;
 211                     }
 212                 }
 213
 214                 let block = fx.get_block(*target);
 215                 fx.bcx.ins().jump(block, &[]);
 216             }
 217             TerminatorKind::Return => {
 218                 crate::abi::codegen_return(fx);
 219             }
 220             TerminatorKind::Assert {
 221                 cond,
 222                 expected,
 223                 msg,
 224                 target,
 225                 cleanup: _,
 226             } => {
 227                 if !fxcodegen_cx.tcx.sess.overflow_checks() {
 228                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 229                         let target = fx.get_block(*target);
 230                         fx.bcx.ins().jump(target, &[]);
 231                         continue;
 232                     }
 233                 }
 234                 let cond = trans_operand(fx, cond).load_scalar(fx);
 235
 236                 let target = fx.get_block(*target);
 237                 let failure = fx.bcx.create_block();
 238                 fx.cold_blocks.insert(failure);
 239
 240                 if *expected {
 241                     fx.bcx.ins().brz(cond, failure, &[]);
 242                 } else {
 243                     fx.bcx.ins().brnz(cond, failure, &[]);
 244                 };
 245                 fx.bcx.ins().jump(target, &[]);
 246
 247                 fx.bcx.switch_to_block(failure);
 248
 249                 let location = fx.get_caller_location(bb_data.terminator().source_info.span).load_scalar(fx);
 250
 251                 let args;
 252                 let lang_item = match msg {
 253                     AssertKind::BoundsCheck { ref len, ref index } => {
 254                         let len = trans_operand(fx, len).load_scalar(fx);
 255                         let index = trans_operand(fx, index).load_scalar(fx);
 256                         args = [index, len, location];
 257                         rustc_hir::lang_items::PanicBoundsCheckFnLangItem
 258                     }
 259                     _ => {
 260                         let msg_str = msg.description();
 261                         let msg_ptr = fx.anonymous_str("assert", msg_str);
 262                         let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 263                         args = [msg_ptr, msg_len, location];
 264                         rustc_hir::lang_items::PanicFnLangItem
 265                     }
 266                 };
 267
 268                 let def_id = fxcodegen_cx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| {
 269                     fxcodegen_cx.tcx.sess.span_fatal(bb_data.terminator().source_info.span, &s)
 270                 });
 271
 272                 let instance = Instance::mono(fxcodegen_cx.tcx, def_id).polymorphize(fxcodegen_cx.tcx);
 273                 let symbol_name = fxcodegen_cx.tcx.symbol_name(instance).name;
 274
 275                 fx.lib_call(&*symbol_name, vec![fx.pointer_type, fx.pointer_type, fx.pointer_type], vec![], &args);
 276
 277                 crate::trap::trap_unreachable(fx, "panic lang item returned");
 278             }
 279
 280             TerminatorKind::SwitchInt {
 281                 discr,
 282                 switch_ty: _,
 283                 values,
 284                 targets,
 285             } => {
 286                 let discr = trans_operand(fx, discr).load_scalar(fx);
 287                 let mut switch = ::cranelift_frontend::Switch::new();
 288                 for (i, value) in values.iter().enumerate() {
 289                     let block = fx.get_block(targets[i]);
 290                     switch.set_entry(*value, block);
 291                 }
 292                 let otherwise_block = fx.get_block(targets[targets.len() - 1]);
 293                 switch.emit(&mut fx.bcx, discr, otherwise_block);
 294             }
 295             TerminatorKind::Call {
 296                 func,
 297                 args,
 298                 destination,
 299                 fn_span,
 300                 cleanup: _,
 301                 from_hir_call: _,
 302             } => {
 303                 fxcodegen_cx.tcx.sess.time("codegen call", || crate::abi::codegen_terminator_call(
 304                     fx,
 305                     *fn_span,
 306                     block,
 307                     func,
 308                     args,
 309                     *destination,
 310                 ));
 311             }
 312             TerminatorKind::InlineAsm {
 313                 template,
 314                 operands,
 315                 options,
 316                 destination,
 317                 line_spans: _,
 318             } => {
 319                 crate::inline_asm::codegen_inline_asm(
 320                     fx,
 321                     bb_data.terminator().source_info.span,
 322                     template,
 323                     operands,
 324                     *options,
 325                 );
 326
 327                 match *destination {
 328                     Some(destination) => {
 329                         let destination_block = fx.get_block(destination);
 330                         fx.bcx.ins().jump(destination_block, &[]);
 331                     }
 332                     None => {
 333                         crate::trap::trap_unreachable(fx, "[corruption] Returned from noreturn inline asm");
 334                     }
 335                 }
 336             }
 337             TerminatorKind::Resume | TerminatorKind::Abort => {
 338                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 339             }
 340             TerminatorKind::Unreachable => {
 341                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 342             }
 343             TerminatorKind::Yield { .. }
 344             | TerminatorKind::FalseEdge { .. }
 345             | TerminatorKind::FalseUnwind { .. }
 346             | TerminatorKind::DropAndReplace { .. }
 347             | TerminatorKind::GeneratorDrop => {
 348                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 349             }
 350             TerminatorKind::Drop {
 351                 place,
 352                 target,
 353                 unwind: _,
 354             } => {
 355                 let drop_place = trans_place(fx, *place);
 356                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 357
 358                 let target_block = fx.get_block(*target);
 359                 fx.bcx.ins().jump(target_block, &[]);
 360             }
 361         };
 362     }
 363
 364     fx.bcx.seal_all_blocks();
 365     fx.bcx.finalize();
 366 }
 367
 368 fn trans_stmt<'tcx>(
 369     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 370     #[allow(unused_variables)]
 371     cur_block: Block,
 372     stmt: &Statement<'tcx>,
 373 ) {
 374     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 375
 376     fx.set_debug_loc(stmt.source_info);
 377
 378     #[cfg(false_debug_assertions)]
 379     match &stmt.kind {
 380         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 381         _ => {
 382             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 383             fx.add_comment(inst, format!("{:?}", stmt));
 384         }
 385     }
 386
 387     match &stmt.kind {
 388         StatementKind::SetDiscriminant {
 389             place,
 390             variant_index,
 391         } => {
 392             let place = trans_place(fx, **place);
 393             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 394         }
 395         StatementKind::Assign(to_place_and_rval) => {
 396             let lval = trans_place(fx, to_place_and_rval.0);
 397             let dest_layout = lval.layout();
 398             match &to_place_and_rval.1 {
 399                 Rvalue::Use(operand) => {
 400                     let val = trans_operand(fx, operand);
 401                     lval.write_cvalue(fx, val);
 402                 }
 403                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 404                     let place = trans_place(fx, *place);
 405                     place.write_place_ref(fx, lval);
 406                 }
 407                 Rvalue::ThreadLocalRef(def_id) => {
 408                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 409                     lval.write_cvalue(fx, val);
 410                 }
 411                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 412                     let lhs = trans_operand(fx, lhs);
 413                     let rhs = trans_operand(fx, rhs);
 414
 415                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 416                     lval.write_cvalue(fx, res);
 417                 }
 418                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 419                     let lhs = trans_operand(fx, lhs);
 420                     let rhs = trans_operand(fx, rhs);
 421
 422                     let res = if !fxcodegen_cx.tcx.sess.overflow_checks() {
 423                         let val =
 424                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 425                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 426                         CValue::by_val_pair(val, is_overflow, lval.layout())
 427                     } else {
 428                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 429                     };
 430
 431                     lval.write_cvalue(fx, res);
 432                 }
 433                 Rvalue::UnaryOp(un_op, operand) => {
 434                     let operand = trans_operand(fx, operand);
 435                     let layout = operand.layout();
 436                     let val = operand.load_scalar(fx);
 437                     let res = match un_op {
 438                         UnOp::Not => {
 439                             match layout.ty.kind {
 440                                 ty::Bool => {
 441                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 442                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 443                                 }
 444                                 ty::Uint(_) | ty::Int(_) => {
 445                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 446                                 }
 447                                 _ => unreachable!("un op Not for {:?}", layout.ty),
 448                             }
 449                         }
 450                         UnOp::Neg => match layout.ty.kind {
 451                             ty::Int(IntTy::I128) => {
 452                                 // FIXME remove this case once ineg.i128 works
 453                                 let zero = CValue::const_val(fx, layout, 0);
 454                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 455                             }
 456                             ty::Int(_) => {
 457                                 CValue::by_val(fx.bcx.ins().ineg(val), layout)
 458                             }
 459                             ty::Float(_) => {
 460                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 461                             }
 462                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 463                         },
 464                     };
 465                     lval.write_cvalue(fx, res);
 466                 }
 467                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 468                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fxcodegen_cx.tcx));
 469                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 470                     match from_ty.kind {
 471                         ty::FnDef(def_id, substs) => {
 472                             let func_ref = fx.get_function_ref(
 473                                 Instance::resolve_for_fn_ptr(fxcodegen_cx.tcx, ParamEnv::reveal_all(), def_id, substs)
 474                                     .unwrap()
 475                                     .polymorphize(fxcodegen_cx.tcx),
 476                             );
 477                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 478                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 479                         }
 480                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 481                     }
 482                 }
 483                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 484                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 485                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 486                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 487                     let operand = trans_operand(fx, operand);
 488                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 489                 }
 490                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 491                     let operand = trans_operand(fx, operand);
 492                     let from_ty = operand.layout().ty;
 493                     let to_ty = fx.monomorphize(to_ty);
 494
 495                     fn is_fat_ptr<'tcx>(
 496                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 497                         ty: Ty<'tcx>,
 498                     ) -> bool {
 499                         ty.builtin_deref(true)
 500                             .map(
 501                                 |ty::TypeAndMut {
 502                                      ty: pointee_ty,
 503                                      mutbl: _,
 504                                  }| has_ptr_meta(fxcodegen_cx.tcx, pointee_ty),
 505                             )
 506                             .unwrap_or(false)
 507                     }
 508
 509                     if is_fat_ptr(fx, from_ty) {
 510                         if is_fat_ptr(fx, to_ty) {
 511                             // fat-ptr -> fat-ptr
 512                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 513                         } else {
 514                             // fat-ptr -> thin-ptr
 515                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 516                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 517                         }
 518                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 519                         // enum -> discriminant value
 520                         assert!(adt_def.is_enum());
 521                         match to_ty.kind {
 522                             ty::Uint(_) | ty::Int(_) => {}
 523                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 524                         }
 525
 526                         use rustc_target::abi::{TagEncoding, Int, Variants};
 527
 528                         match &operand.layout().variants {
 529                             Variants::Single { index } => {
 530                                 let discr = operand.layout().ty.discriminant_for_variant(fxcodegen_cx.tcx, *index).unwrap();
 531                                 let discr = if discr.ty.is_signed() {
 532                                     rustc_middle::mir::interpret::sign_extend(discr.val, fx.layout_of(discr.ty).size)
 533                                 } else {
 534                                     discr.val
 535                                 };
 536
 537                                 let discr = CValue::const_val(fx, fx.layout_of(to_ty), discr);
 538                                 lval.write_cvalue(fx, discr);
 539                             }
 540                             Variants::Multiple {
 541                                 tag,
 542                                 tag_field,
 543                                 tag_encoding: TagEncoding::Direct,
 544                                 variants: _,
 545                             } => {
 546                                 let cast_to = fx.clif_type(dest_layout.ty).unwrap();
 547
 548                                 // Read the tag/niche-encoded discriminant from memory.
 549                                 let encoded_discr = operand.value_field(fx, mir::Field::new(*tag_field));
 550                                 let encoded_discr = encoded_discr.load_scalar(fx);
 551
 552                                 // Decode the discriminant (specifically if it's niche-encoded).
 553                                 let signed = match tag.value {
 554                                     Int(_, signed) => signed,
 555                                     _ => false,
 556                                 };
 557                                 let val = clif_intcast(fx, encoded_discr, cast_to, signed);
 558                                 let val = CValue::by_val(val, dest_layout);
 559                                 lval.write_cvalue(fx, val);
 560                             }
 561                             Variants::Multiple { ..} => unreachable!(),
 562                         }
 563                     } else {
 564                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 565                         let from = operand.load_scalar(fx);
 566
 567                         let res = clif_int_or_float_cast(
 568                             fx,
 569                             from,
 570                             type_sign(from_ty),
 571                             to_clif_ty,
 572                             type_sign(to_ty),
 573                         );
 574                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 575                     }
 576                 }
 577                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
 578                     let operand = trans_operand(fx, operand);
 579                     match operand.layout().ty.kind {
 580                         ty::Closure(def_id, substs) => {
 581                             let instance = Instance::resolve_closure(
 582                                 fxcodegen_cx.tcx,
 583                                 def_id,
 584                                 substs,
 585                                 ty::ClosureKind::FnOnce,
 586                             ).polymorphize(fxcodegen_cx.tcx);
 587                             let func_ref = fx.get_function_ref(instance);
 588                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 589                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 590                         }
 591                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 592                     }
 593                 }
 594                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 595                     let operand = trans_operand(fx, operand);
 596                     operand.unsize_value(fx, lval);
 597                 }
 598                 Rvalue::Discriminant(place) => {
 599                     let place = trans_place(fx, *place);
 600                     let value = place.to_cvalue(fx);
 601                     let discr =
 602                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 603                     lval.write_cvalue(fx, discr);
 604                 }
 605                 Rvalue::Repeat(operand, times) => {
 606                     let operand = trans_operand(fx, operand);
 607                     let times = fx
 608                         .monomorphize(times)
 609                         .eval(fxcodegen_cx.tcx, ParamEnv::reveal_all())
 610                         .val
 611                         .try_to_bits(fxcodegen_cx.tcx.data_layout.pointer_size)
 612                         .unwrap();
 613                     for i in 0..times {
 614                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 615                         let to = lval.place_index(fx, index);
 616                         to.write_cvalue(fx, operand);
 617                     }
 618                 }
 619                 Rvalue::Len(place) => {
 620                     let place = trans_place(fx, *place);
 621                     let usize_layout = fx.layout_of(fxcodegen_cx.tcx.types.usize);
 622                     let len = codegen_array_len(fx, place);
 623                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 624                 }
 625                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 626                     use rustc_hir::lang_items::ExchangeMallocFnLangItem;
 627
 628                     let usize_type = fx.clif_type(fxcodegen_cx.tcx.types.usize).unwrap();
 629                     let content_ty = fx.monomorphize(content_ty);
 630                     let layout = fx.layout_of(content_ty);
 631                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 632                     let llalign = fx
 633                         .bcx
 634                         .ins()
 635                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 636                     let box_layout = fx.layout_of(fxcodegen_cx.tcx.mk_box(content_ty));
 637
 638                     // Allocate space:
 639                     let def_id = match fxcodegen_cx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 640                         Ok(id) => id,
 641                         Err(s) => {
 642                             fxcodegen_cx.tcx
 643                                 .sess
 644                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 645                         }
 646                     };
 647                     let instance = ty::Instance::mono(fxcodegen_cx.tcx, def_id).polymorphize(fxcodegen_cx.tcx);
 648                     let func_ref = fx.get_function_ref(instance);
 649                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 650                     let ptr = fx.bcx.inst_results(call)[0];
 651                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 652                 }
 653                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 654                     assert!(lval
 655                         .layout()
 656                         .ty
 657                         .is_sized(fxcodegen_cx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 658                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 659                     let val = CValue::const_val(fx, fx.layout_of(fxcodegen_cx.tcx.types.usize), ty_size.into());
 660                     lval.write_cvalue(fx, val);
 661                 }
 662                 Rvalue::Aggregate(kind, operands) => match **kind {
 663                     AggregateKind::Array(_ty) => {
 664                         for (i, operand) in operands.into_iter().enumerate() {
 665                             let operand = trans_operand(fx, operand);
 666                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 667                             let to = lval.place_index(fx, index);
 668                             to.write_cvalue(fx, operand);
 669                         }
 670                     }
 671                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 672                 },
 673             }
 674         }
 675         StatementKind::StorageLive(_)
 676         | StatementKind::StorageDead(_)
 677         | StatementKind::Nop
 678         | StatementKind::FakeRead(..)
 679         | StatementKind::Retag { .. }
 680         | StatementKind::AscribeUserType(..) => {}
 681
 682         StatementKind::LlvmInlineAsm(asm) => {
 683             use rustc_span::symbol::Symbol;
 684             let LlvmInlineAsm {
 685                 asm,
 686                 outputs,
 687                 inputs,
 688             } = &**asm;
 689             let rustc_hir::LlvmInlineAsmInner {
 690                 asm: asm_code, // Name
 691                 outputs: output_names, // Vec<LlvmInlineAsmOutput>
 692                 inputs: input_names,   // Vec<Name>
 693                 clobbers,      // Vec<Name>
 694                 volatile,      // bool
 695                 alignstack,    // bool
 696                 dialect: _,
 697                 asm_str_style: _,
 698             } = asm;
 699             match asm_code.as_str().trim() {
 700                 "" => {
 701                     // Black box
 702                 }
 703                 "mov %rbx, %rsi\n                  cpuid\n                  xchg %rbx, %rsi" => {
 704                     assert_eq!(input_names, &[Symbol::intern("{eax}"), Symbol::intern("{ecx}")]);
 705                     assert_eq!(output_names.len(), 4);
 706                     for (i, c) in (&["={eax}", "={esi}", "={ecx}", "={edx}"]).iter().enumerate() {
 707                         assert_eq!(&output_names[i].constraint.as_str(), c);
 708                         assert!(!output_names[i].is_rw);
 709                         assert!(!output_names[i].is_indirect);
 710                     }
 711
 712                     assert_eq!(clobbers, &[]);
 713
 714                     assert!(!volatile);
 715                     assert!(!alignstack);
 716
 717                     assert_eq!(inputs.len(), 2);
 718                     let leaf = trans_operand(fx, &inputs[0].1).load_scalar(fx); // %eax
 719                     let subleaf = trans_operand(fx, &inputs[1].1).load_scalar(fx); // %ecx
 720
 721                     let (eax, ebx, ecx, edx) = crate::intrinsics::codegen_cpuid_call(fx, leaf, subleaf);
 722
 723                     assert_eq!(outputs.len(), 4);
 724                     trans_place(fx, outputs[0]).write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fxcodegen_cx.tcx.types.u32)));
 725                     trans_place(fx, outputs[1]).write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fxcodegen_cx.tcx.types.u32)));
 726                     trans_place(fx, outputs[2]).write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fxcodegen_cx.tcx.types.u32)));
 727                     trans_place(fx, outputs[3]).write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fxcodegen_cx.tcx.types.u32)));
 728                 }
 729                 "xgetbv" => {
 730                     assert_eq!(input_names, &[Symbol::intern("{ecx}")]);
 731
 732                     assert_eq!(output_names.len(), 2);
 733                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 734                         assert_eq!(&output_names[i].constraint.as_str(), c);
 735                         assert!(!output_names[i].is_rw);
 736                         assert!(!output_names[i].is_indirect);
 737                     }
 738
 739                     assert_eq!(clobbers, &[]);
 740
 741                     assert!(!volatile);
 742                     assert!(!alignstack);
 743
 744                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 745                 }
 746                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 747                 _ if fxcodegen_cx.tcx.symbol_name(fx.instance).name.starts_with("___chkstk") => {
 748                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 749                 }
 750                 _ if fxcodegen_cx.tcx.symbol_name(fx.instance).name == "__alloca" => {
 751                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 752                 }
 753                 // Used in sys::windows::abort_internal
 754                 "int $$0x29" => {
 755                     crate::trap::trap_unimplemented(fx, "Windows abort");
 756                 }
 757                 _ => fxcodegen_cx.tcx.sess.span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 758             }
 759         }
 760     }
 761 }
 762
 763 fn codegen_array_len<'tcx>(
 764     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 765     place: CPlace<'tcx>,
 766 ) -> Value {
 767     match place.layout().ty.kind {
 768         ty::Array(_elem_ty, len) => {
 769             let len = fx.monomorphize(&len)
 770                 .eval(fxcodegen_cx.tcx, ParamEnv::reveal_all())
 771                 .eval_usize(fxcodegen_cx.tcx, ParamEnv::reveal_all()) as i64;
 772             fx.bcx.ins().iconst(fx.pointer_type, len)
 773         }
 774         ty::Slice(_elem_ty) => place
 775             .to_ptr_maybe_unsized()
 776             .1
 777             .expect("Length metadata for slice place"),
 778         _ => bug!("Rvalue::Len({:?})", place),
 779     }
 780 }
 781
 782 pub(crate) fn trans_place<'tcx>(
 783     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 784     place: Place<'tcx>,
 785 ) -> CPlace<'tcx> {
 786     let mut cplace = fx.get_local_place(place.local);
 787
 788     for elem in place.projection {
 789         match elem {
 790             PlaceElem::Deref => {
 791                 cplace = cplace.place_deref(fx);
 792             }
 793             PlaceElem::Field(field, _ty) => {
 794                 cplace = cplace.place_field(fx, field);
 795             }
 796             PlaceElem::Index(local) => {
 797                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 798                 cplace = cplace.place_index(fx, index);
 799             }
 800             PlaceElem::ConstantIndex {
 801                 offset,
 802                 min_length: _,
 803                 from_end,
 804             } => {
 805                 let index = if !from_end {
 806                     fx.bcx.ins().iconst(fx.pointer_type, i64::from(offset))
 807                 } else {
 808                     let len = codegen_array_len(fx, cplace);
 809                     fx.bcx.ins().iadd_imm(len, -i64::from(offset))
 810                 };
 811                 cplace = cplace.place_index(fx, index);
 812             }
 813             PlaceElem::Subslice { from, to, from_end } => {
 814                 // These indices are generated by slice patterns.
 815                 // slice[from:-to] in Python terms.
 816
 817                 match cplace.layout().ty.kind {
 818                     ty::Array(elem_ty, _len) => {
 819                         assert!(!from_end, "array subslices are never `from_end`");
 820                         let elem_layout = fx.layout_of(elem_ty);
 821                         let ptr = cplace.to_ptr();
 822                         cplace = CPlace::for_ptr(
 823                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * i64::from(from)),
 824                             fx.layout_of(fxcodegen_cx.tcx.mk_array(elem_ty, u64::from(to) - u64::from(from))),
 825                         );
 826                     }
 827                     ty::Slice(elem_ty) => {
 828                         assert!(from_end, "slice subslices should be `from_end`");
 829                         let elem_layout = fx.layout_of(elem_ty);
 830                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 831                         let len = len.unwrap();
 832                         cplace = CPlace::for_ptr_with_extra(
 833                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * i64::from(from)),
 834                             fx.bcx.ins().iadd_imm(len, -(i64::from(from) + i64::from(to))),
 835                             cplace.layout(),
 836                         );
 837                     }
 838                     _ => unreachable!(),
 839                 }
 840             }
 841             PlaceElem::Downcast(_adt_def, variant) => {
 842                 cplace = cplace.downcast_variant(fx, variant);
 843             }
 844         }
 845     }
 846
 847     cplace
 848 }
 849
 850 pub(crate) fn trans_operand<'tcx>(
 851     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 852     operand: &Operand<'tcx>,
 853 ) -> CValue<'tcx> {
 854     match operand {
 855         Operand::Move(place) | Operand::Copy(place) => {
 856             let cplace = trans_place(fx, *place);
 857             cplace.to_cvalue(fx)
 858         }
 859         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 860     }
 861 }