src/base.rs

   1 //! Codegen of a single function
   2
   3 use rustc_index::vec::IndexVec;
   4 use rustc_middle::ty::adjustment::PointerCast;
   5
   6 use crate::prelude::*;
   7
   8 pub(crate) fn codegen_fn<'tcx>(
   9     cx: &mut crate::CodegenCx<'tcx, impl Module>,
  10     instance: Instance<'tcx>,
  11     linkage: Linkage,
  12 ) {
  13     let tcx = cx.tcx;
  14
  15     let mir = tcx.instance_mir(instance.def);
  16
  17     // Declare function
  18     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  19     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  20
  21     cx.cached_context.clear();
  22
  23     // Make the FunctionBuilder
  24     let mut func_ctx = FunctionBuilderContext::new();
  25     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  26     func.name = ExternalName::user(0, func_id.as_u32());
  27     func.signature = sig;
  28     func.collect_debug_info();
  29
  30     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  31
  32     // Predefine blocks
  33     let start_block = bcx.create_block();
  34     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len())
  35         .map(|_| bcx.create_block())
  36         .collect();
  37
  38     // Make FunctionCx
  39     let pointer_type = cx.module.target_config().pointer_type();
  40     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  41
  42     let mut fx = FunctionCx {
  43         cx,
  44         tcx,
  45         pointer_type,
  46
  47         instance,
  48         mir,
  49
  50         bcx,
  51         block_map,
  52         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  53         caller_location: None, // set by `codegen_fn_prelude`
  54         cold_blocks: EntitySet::new(),
  55
  56         clif_comments,
  57         source_info_set: indexmap::IndexSet::new(),
  58         next_ssa_var: 0,
  59
  60         inline_asm_index: 0,
  61     };
  62
  63     let arg_uninhabited = fx.mir.args_iter().any(|arg| {
  64         fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty))
  65             .abi
  66             .is_uninhabited()
  67     });
  68
  69     if arg_uninhabited {
  70         fx.bcx
  71             .append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  72         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  73         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  74     } else {
  75         tcx.sess.time("codegen clif ir", || {
  76             tcx.sess.time("codegen prelude", || {
  77                 crate::abi::codegen_fn_prelude(&mut fx, start_block)
  78             });
  79             codegen_fn_content(&mut fx);
  80         });
  81     }
  82
  83     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  84     let instance = fx.instance;
  85     let mut clif_comments = fx.clif_comments;
  86     let source_info_set = fx.source_info_set;
  87     let local_map = fx.local_map;
  88     let cold_blocks = fx.cold_blocks;
  89
  90     // Store function in context
  91     let context = &mut cx.cached_context;
  92     context.func = func;
  93
  94     crate::pretty_clif::write_clif_file(tcx, "unopt", None, instance, &context, &clif_comments);
  95
  96     // Verify function
  97     verify_func(tcx, &clif_comments, &context.func);
  98
  99     // Perform rust specific optimizations
 100     tcx.sess.time("optimize clif ir", || {
 101         crate::optimize::optimize_function(
 102             tcx,
 103             instance,
 104             context,
 105             &cold_blocks,
 106             &mut clif_comments,
 107         );
 108     });
 109
 110     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 111     // instruction, which doesn't have an encoding.
 112     context.compute_cfg();
 113     context.compute_domtree();
 114     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 115     context.dce(cx.module.isa()).unwrap();
 116
 117     // Define function
 118     let module = &mut cx.module;
 119     tcx.sess.time("define function", || {
 120         module
 121             .define_function(
 122                 func_id,
 123                 context,
 124                 &mut cranelift_codegen::binemit::NullTrapSink {},
 125             )
 126             .unwrap()
 127     });
 128
 129     // Write optimized function to file for debugging
 130     crate::pretty_clif::write_clif_file(
 131         tcx,
 132         "opt",
 133         Some(cx.module.isa()),
 134         instance,
 135         &context,
 136         &clif_comments,
 137     );
 138
 139     // Define debuginfo for function
 140     let isa = cx.module.isa();
 141     let debug_context = &mut cx.debug_context;
 142     let unwind_context = &mut cx.unwind_context;
 143     tcx.sess.time("generate debug info", || {
 144         if let Some(debug_context) = debug_context {
 145             debug_context.define_function(
 146                 instance,
 147                 func_id,
 148                 &name,
 149                 isa,
 150                 context,
 151                 &source_info_set,
 152                 local_map,
 153             );
 154         }
 155         unwind_context.add_function(func_id, &context, isa);
 156     });
 157
 158     // Clear context to make it usable for the next function
 159     context.clear();
 160 }
 161
 162 pub(crate) fn verify_func(
 163     tcx: TyCtxt<'_>,
 164     writer: &crate::pretty_clif::CommentWriter,
 165     func: &Function,
 166 ) {
 167     tcx.sess.time("verify clif ir", || {
 168         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 169         match cranelift_codegen::verify_function(&func, &flags) {
 170             Ok(_) => {}
 171             Err(err) => {
 172                 tcx.sess.err(&format!("{:?}", err));
 173                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 174                     &func,
 175                     None,
 176                     Some(Box::new(writer)),
 177                     err,
 178                 );
 179                 tcx.sess
 180                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 181             }
 182         }
 183     });
 184 }
 185
 186 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Module>) {
 187     crate::constant::check_constants(fx);
 188
 189     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 190         let block = fx.get_block(bb);
 191         fx.bcx.switch_to_block(block);
 192
 193         if bb_data.is_cleanup {
 194             // Unwinding after panicking is not supported
 195             continue;
 196
 197             // FIXME once unwinding is supported uncomment next lines
 198             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 199             // fx.cold_blocks.insert(block);
 200         }
 201
 202         fx.bcx.ins().nop();
 203         for stmt in &bb_data.statements {
 204             fx.set_debug_loc(stmt.source_info);
 205             codegen_stmt(fx, block, stmt);
 206         }
 207
 208         #[cfg(debug_assertions)]
 209         {
 210             let mut terminator_head = "\n".to_string();
 211             bb_data
 212                 .terminator()
 213                 .kind
 214                 .fmt_head(&mut terminator_head)
 215                 .unwrap();
 216             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 217             fx.add_comment(inst, terminator_head);
 218         }
 219
 220         fx.set_debug_loc(bb_data.terminator().source_info);
 221
 222         match &bb_data.terminator().kind {
 223             TerminatorKind::Goto { target } => {
 224                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 225                     let mut can_immediately_return = true;
 226                     for stmt in &fx.mir[*target].statements {
 227                         if let StatementKind::StorageDead(_) = stmt.kind {
 228                         } else {
 229                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 230                             can_immediately_return = false;
 231                             break;
 232                         }
 233                     }
 234
 235                     if can_immediately_return {
 236                         crate::abi::codegen_return(fx);
 237                         continue;
 238                     }
 239                 }
 240
 241                 let block = fx.get_block(*target);
 242                 fx.bcx.ins().jump(block, &[]);
 243             }
 244             TerminatorKind::Return => {
 245                 crate::abi::codegen_return(fx);
 246             }
 247             TerminatorKind::Assert {
 248                 cond,
 249                 expected,
 250                 msg,
 251                 target,
 252                 cleanup: _,
 253             } => {
 254                 if !fx.tcx.sess.overflow_checks() {
 255                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 256                         let target = fx.get_block(*target);
 257                         fx.bcx.ins().jump(target, &[]);
 258                         continue;
 259                     }
 260                 }
 261                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 262
 263                 let target = fx.get_block(*target);
 264                 let failure = fx.bcx.create_block();
 265                 fx.cold_blocks.insert(failure);
 266
 267                 if *expected {
 268                     fx.bcx.ins().brz(cond, failure, &[]);
 269                 } else {
 270                     fx.bcx.ins().brnz(cond, failure, &[]);
 271                 };
 272                 fx.bcx.ins().jump(target, &[]);
 273
 274                 fx.bcx.switch_to_block(failure);
 275                 fx.bcx.ins().nop();
 276
 277                 match msg {
 278                     AssertKind::BoundsCheck { ref len, ref index } => {
 279                         let len = codegen_operand(fx, len).load_scalar(fx);
 280                         let index = codegen_operand(fx, index).load_scalar(fx);
 281                         let location = fx
 282                             .get_caller_location(bb_data.terminator().source_info.span)
 283                             .load_scalar(fx);
 284
 285                         codegen_panic_inner(
 286                             fx,
 287                             rustc_hir::LangItem::PanicBoundsCheck,
 288                             &[index, len, location],
 289                             bb_data.terminator().source_info.span,
 290                         );
 291                     }
 292                     _ => {
 293                         let msg_str = msg.description();
 294                         codegen_panic(fx, msg_str, bb_data.terminator().source_info.span);
 295                     }
 296                 }
 297             }
 298
 299             TerminatorKind::SwitchInt {
 300                 discr,
 301                 switch_ty,
 302                 targets,
 303             } => {
 304                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 305
 306                 if switch_ty.kind() == fx.tcx.types.bool.kind() {
 307                     assert_eq!(targets.iter().count(), 1);
 308                     let (then_value, then_block) = targets.iter().next().unwrap();
 309                     let then_block = fx.get_block(then_block);
 310                     let else_block = fx.get_block(targets.otherwise());
 311                     let test_zero = match then_value {
 312                         0 => true,
 313                         1 => false,
 314                         _ => unreachable!("{:?}", targets),
 315                     };
 316
 317                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 318                     let (discr, is_inverted) =
 319                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 320                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 321                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 322                     let discr =
 323                         crate::optimize::peephole::make_branchable_value(&mut fx.bcx, discr);
 324                     if test_zero {
 325                         fx.bcx.ins().brz(discr, then_block, &[]);
 326                         fx.bcx.ins().jump(else_block, &[]);
 327                     } else {
 328                         fx.bcx.ins().brnz(discr, then_block, &[]);
 329                         fx.bcx.ins().jump(else_block, &[]);
 330                     }
 331                 } else {
 332                     let mut switch = ::cranelift_frontend::Switch::new();
 333                     for (value, block) in targets.iter() {
 334                         let block = fx.get_block(block);
 335                         switch.set_entry(value, block);
 336                     }
 337                     let otherwise_block = fx.get_block(targets.otherwise());
 338                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 339                 }
 340             }
 341             TerminatorKind::Call {
 342                 func,
 343                 args,
 344                 destination,
 345                 fn_span,
 346                 cleanup: _,
 347                 from_hir_call: _,
 348             } => {
 349                 fx.tcx.sess.time("codegen call", || {
 350                     crate::abi::codegen_terminator_call(
 351                         fx,
 352                         *fn_span,
 353                         block,
 354                         func,
 355                         args,
 356                         *destination,
 357                     )
 358                 });
 359             }
 360             TerminatorKind::InlineAsm {
 361                 template,
 362                 operands,
 363                 options,
 364                 destination,
 365                 line_spans: _,
 366             } => {
 367                 crate::inline_asm::codegen_inline_asm(
 368                     fx,
 369                     bb_data.terminator().source_info.span,
 370                     template,
 371                     operands,
 372                     *options,
 373                 );
 374
 375                 match *destination {
 376                     Some(destination) => {
 377                         let destination_block = fx.get_block(destination);
 378                         fx.bcx.ins().jump(destination_block, &[]);
 379                     }
 380                     None => {
 381                         crate::trap::trap_unreachable(
 382                             fx,
 383                             "[corruption] Returned from noreturn inline asm",
 384                         );
 385                     }
 386                 }
 387             }
 388             TerminatorKind::Resume | TerminatorKind::Abort => {
 389                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 390             }
 391             TerminatorKind::Unreachable => {
 392                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 393             }
 394             TerminatorKind::Yield { .. }
 395             | TerminatorKind::FalseEdge { .. }
 396             | TerminatorKind::FalseUnwind { .. }
 397             | TerminatorKind::DropAndReplace { .. }
 398             | TerminatorKind::GeneratorDrop => {
 399                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 400             }
 401             TerminatorKind::Drop {
 402                 place,
 403                 target,
 404                 unwind: _,
 405             } => {
 406                 let drop_place = codegen_place(fx, *place);
 407                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 408
 409                 let target_block = fx.get_block(*target);
 410                 fx.bcx.ins().jump(target_block, &[]);
 411             }
 412         };
 413     }
 414
 415     fx.bcx.seal_all_blocks();
 416     fx.bcx.finalize();
 417 }
 418
 419 fn codegen_stmt<'tcx>(
 420     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 421     #[allow(unused_variables)] cur_block: Block,
 422     stmt: &Statement<'tcx>,
 423 ) {
 424     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 425
 426     fx.set_debug_loc(stmt.source_info);
 427
 428     #[cfg(false_debug_assertions)]
 429     match &stmt.kind {
 430         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 431         _ => {
 432             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 433             fx.add_comment(inst, format!("{:?}", stmt));
 434         }
 435     }
 436
 437     match &stmt.kind {
 438         StatementKind::SetDiscriminant {
 439             place,
 440             variant_index,
 441         } => {
 442             let place = codegen_place(fx, **place);
 443             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 444         }
 445         StatementKind::Assign(to_place_and_rval) => {
 446             let lval = codegen_place(fx, to_place_and_rval.0);
 447             let dest_layout = lval.layout();
 448             match &to_place_and_rval.1 {
 449                 Rvalue::Use(operand) => {
 450                     let val = codegen_operand(fx, operand);
 451                     lval.write_cvalue(fx, val);
 452                 }
 453                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 454                     let place = codegen_place(fx, *place);
 455                     let ref_ = place.place_ref(fx, lval.layout());
 456                     lval.write_cvalue(fx, ref_);
 457                 }
 458                 Rvalue::ThreadLocalRef(def_id) => {
 459                     let val = crate::constant::codegen_tls_ref(fx, *def_id, lval.layout());
 460                     lval.write_cvalue(fx, val);
 461                 }
 462                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 463                     let lhs = codegen_operand(fx, lhs);
 464                     let rhs = codegen_operand(fx, rhs);
 465
 466                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 467                     lval.write_cvalue(fx, res);
 468                 }
 469                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 470                     let lhs = codegen_operand(fx, lhs);
 471                     let rhs = codegen_operand(fx, rhs);
 472
 473                     let res = if !fx.tcx.sess.overflow_checks() {
 474                         let val =
 475                             crate::num::codegen_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 476                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 477                         CValue::by_val_pair(val, is_overflow, lval.layout())
 478                     } else {
 479                         crate::num::codegen_checked_int_binop(fx, *bin_op, lhs, rhs)
 480                     };
 481
 482                     lval.write_cvalue(fx, res);
 483                 }
 484                 Rvalue::UnaryOp(un_op, operand) => {
 485                     let operand = codegen_operand(fx, operand);
 486                     let layout = operand.layout();
 487                     let val = operand.load_scalar(fx);
 488                     let res = match un_op {
 489                         UnOp::Not => match layout.ty.kind() {
 490                             ty::Bool => {
 491                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 492                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 493                             }
 494                             ty::Uint(_) | ty::Int(_) => {
 495                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 496                             }
 497                             _ => unreachable!("un op Not for {:?}", layout.ty),
 498                         },
 499                         UnOp::Neg => match layout.ty.kind() {
 500                             ty::Int(IntTy::I128) => {
 501                                 // FIXME remove this case once ineg.i128 works
 502                                 let zero = CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 503                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 504                             }
 505                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 506                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 507                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 508                         },
 509                     };
 510                     lval.write_cvalue(fx, res);
 511                 }
 512                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
 513                     let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
 514                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 515                     match *from_ty.kind() {
 516                         ty::FnDef(def_id, substs) => {
 517                             let func_ref = fx.get_function_ref(
 518                                 Instance::resolve_for_fn_ptr(
 519                                     fx.tcx,
 520                                     ParamEnv::reveal_all(),
 521                                     def_id,
 522                                     substs,
 523                                 )
 524                                 .unwrap()
 525                                 .polymorphize(fx.tcx),
 526                             );
 527                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 528                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 529                         }
 530                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 531                     }
 532                 }
 533                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
 534                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
 535                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
 536                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 537                     let operand = codegen_operand(fx, operand);
 538                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 539                 }
 540                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 541                     let operand = codegen_operand(fx, operand);
 542                     let from_ty = operand.layout().ty;
 543                     let to_ty = fx.monomorphize(to_ty);
 544
 545                     fn is_fat_ptr<'tcx>(
 546                         fx: &FunctionCx<'_, 'tcx, impl Module>,
 547                         ty: Ty<'tcx>,
 548                     ) -> bool {
 549                         ty.builtin_deref(true)
 550                             .map(
 551                                 |ty::TypeAndMut {
 552                                      ty: pointee_ty,
 553                                      mutbl: _,
 554                                  }| {
 555                                     has_ptr_meta(fx.tcx, pointee_ty)
 556                                 },
 557                             )
 558                             .unwrap_or(false)
 559                     }
 560
 561                     if is_fat_ptr(fx, from_ty) {
 562                         if is_fat_ptr(fx, to_ty) {
 563                             // fat-ptr -> fat-ptr
 564                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 565                         } else {
 566                             // fat-ptr -> thin-ptr
 567                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 568                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 569                         }
 570                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 571                         // enum -> discriminant value
 572                         assert!(adt_def.is_enum());
 573                         match to_ty.kind() {
 574                             ty::Uint(_) | ty::Int(_) => {}
 575                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 576                         }
 577
 578                         use rustc_target::abi::{Int, TagEncoding, Variants};
 579
 580                         match &operand.layout().variants {
 581                             Variants::Single { index } => {
 582                                 let discr = operand
 583                                     .layout()
 584                                     .ty
 585                                     .discriminant_for_variant(fx.tcx, *index)
 586                                     .unwrap();
 587                                 let discr = if discr.ty.is_signed() {
 588                                     fx.layout_of(discr.ty).size.sign_extend(discr.val)
 589                                 } else {
 590                                     discr.val
 591                                 };
 592                                 let discr = discr.into();
 593
 594                                 let discr = CValue::const_val(fx, fx.layout_of(to_ty), discr);
 595                                 lval.write_cvalue(fx, discr);
 596                             }
 597                             Variants::Multiple {
 598                                 tag,
 599                                 tag_field,
 600                                 tag_encoding: TagEncoding::Direct,
 601                                 variants: _,
 602                             } => {
 603                                 let cast_to = fx.clif_type(dest_layout.ty).unwrap();
 604
 605                                 // Read the tag/niche-encoded discriminant from memory.
 606                                 let encoded_discr =
 607                                     operand.value_field(fx, mir::Field::new(*tag_field));
 608                                 let encoded_discr = encoded_discr.load_scalar(fx);
 609
 610                                 // Decode the discriminant (specifically if it's niche-encoded).
 611                                 let signed = match tag.value {
 612                                     Int(_, signed) => signed,
 613                                     _ => false,
 614                                 };
 615                                 let val = clif_intcast(fx, encoded_discr, cast_to, signed);
 616                                 let val = CValue::by_val(val, dest_layout);
 617                                 lval.write_cvalue(fx, val);
 618                             }
 619                             Variants::Multiple { .. } => unreachable!(),
 620                         }
 621                     } else {
 622                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 623                         let from = operand.load_scalar(fx);
 624
 625                         let res = clif_int_or_float_cast(
 626                             fx,
 627                             from,
 628                             type_sign(from_ty),
 629                             to_clif_ty,
 630                             type_sign(to_ty),
 631                         );
 632                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 633                     }
 634                 }
 635                 Rvalue::Cast(
 636                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 637                     operand,
 638                     _to_ty,
 639                 ) => {
 640                     let operand = codegen_operand(fx, operand);
 641                     match *operand.layout().ty.kind() {
 642                         ty::Closure(def_id, substs) => {
 643                             let instance = Instance::resolve_closure(
 644                                 fx.tcx,
 645                                 def_id,
 646                                 substs,
 647                                 ty::ClosureKind::FnOnce,
 648                             )
 649                             .polymorphize(fx.tcx);
 650                             let func_ref = fx.get_function_ref(instance);
 651                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 652                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 653                         }
 654                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 655                     }
 656                 }
 657                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
 658                     let operand = codegen_operand(fx, operand);
 659                     operand.unsize_value(fx, lval);
 660                 }
 661                 Rvalue::Discriminant(place) => {
 662                     let place = codegen_place(fx, *place);
 663                     let value = place.to_cvalue(fx);
 664                     let discr =
 665                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 666                     lval.write_cvalue(fx, discr);
 667                 }
 668                 Rvalue::Repeat(operand, times) => {
 669                     let operand = codegen_operand(fx, operand);
 670                     let times = fx
 671                         .monomorphize(times)
 672                         .eval(fx.tcx, ParamEnv::reveal_all())
 673                         .val
 674                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 675                         .unwrap();
 676                     if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 677                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 678                         // FIXME use emit_small_memset where possible
 679                         let addr = lval.to_ptr().get_addr(fx);
 680                         let val = operand.load_scalar(fx);
 681                         fx.bcx
 682                             .call_memset(fx.cx.module.target_config(), addr, val, times);
 683                     } else {
 684                         let loop_block = fx.bcx.create_block();
 685                         let loop_block2 = fx.bcx.create_block();
 686                         let done_block = fx.bcx.create_block();
 687                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 688                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 689                         fx.bcx.ins().jump(loop_block, &[zero]);
 690
 691                         fx.bcx.switch_to_block(loop_block);
 692                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 693                         fx.bcx.ins().brnz(done, done_block, &[]);
 694                         fx.bcx.ins().jump(loop_block2, &[]);
 695
 696                         fx.bcx.switch_to_block(loop_block2);
 697                         let to = lval.place_index(fx, index);
 698                         to.write_cvalue(fx, operand);
 699                         let index = fx.bcx.ins().iadd_imm(index, 1);
 700                         fx.bcx.ins().jump(loop_block, &[index]);
 701
 702                         fx.bcx.switch_to_block(done_block);
 703                         fx.bcx.ins().nop();
 704                     }
 705                 }
 706                 Rvalue::Len(place) => {
 707                     let place = codegen_place(fx, *place);
 708                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 709                     let len = codegen_array_len(fx, place);
 710                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 711                 }
 712                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 713                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 714                     let content_ty = fx.monomorphize(content_ty);
 715                     let layout = fx.layout_of(content_ty);
 716                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 717                     let llalign = fx
 718                         .bcx
 719                         .ins()
 720                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 721                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 722
 723                     // Allocate space:
 724                     let def_id = match fx
 725                         .tcx
 726                         .lang_items()
 727                         .require(rustc_hir::LangItem::ExchangeMalloc)
 728                     {
 729                         Ok(id) => id,
 730                         Err(s) => {
 731                             fx.tcx
 732                                 .sess
 733                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 734                         }
 735                     };
 736                     let instance = ty::Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 737                     let func_ref = fx.get_function_ref(instance);
 738                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 739                     let ptr = fx.bcx.inst_results(call)[0];
 740                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 741                 }
 742                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 743                     assert!(lval
 744                         .layout()
 745                         .ty
 746                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 747                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 748                     let val =
 749                         CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 750                     lval.write_cvalue(fx, val);
 751                 }
 752                 Rvalue::Aggregate(kind, operands) => match **kind {
 753                     AggregateKind::Array(_ty) => {
 754                         for (i, operand) in operands.iter().enumerate() {
 755                             let operand = codegen_operand(fx, operand);
 756                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 757                             let to = lval.place_index(fx, index);
 758                             to.write_cvalue(fx, operand);
 759                         }
 760                     }
 761                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 762                 },
 763             }
 764         }
 765         StatementKind::StorageLive(_)
 766         | StatementKind::StorageDead(_)
 767         | StatementKind::Nop
 768         | StatementKind::FakeRead(..)
 769         | StatementKind::Retag { .. }
 770         | StatementKind::AscribeUserType(..) => {}
 771
 772         StatementKind::LlvmInlineAsm(asm) => {
 773             use rustc_span::symbol::Symbol;
 774             let LlvmInlineAsm {
 775                 asm,
 776                 outputs,
 777                 inputs,
 778             } = &**asm;
 779             let rustc_hir::LlvmInlineAsmInner {
 780                 asm: asm_code,         // Name
 781                 outputs: output_names, // Vec<LlvmInlineAsmOutput>
 782                 inputs: input_names,   // Vec<Name>
 783                 clobbers,              // Vec<Name>
 784                 volatile,              // bool
 785                 alignstack,            // bool
 786                 dialect: _,
 787                 asm_str_style: _,
 788             } = asm;
 789             match asm_code.as_str().trim() {
 790                 "" => {
 791                     // Black box
 792                 }
 793                 "mov %rbx, %rsi\n                  cpuid\n                  xchg %rbx, %rsi" => {
 794                     assert_eq!(
 795                         input_names,
 796                         &[Symbol::intern("{eax}"), Symbol::intern("{ecx}")]
 797                     );
 798                     assert_eq!(output_names.len(), 4);
 799                     for (i, c) in (&["={eax}", "={esi}", "={ecx}", "={edx}"])
 800                         .iter()
 801                         .enumerate()
 802                     {
 803                         assert_eq!(&output_names[i].constraint.as_str(), c);
 804                         assert!(!output_names[i].is_rw);
 805                         assert!(!output_names[i].is_indirect);
 806                     }
 807
 808                     assert_eq!(clobbers, &[]);
 809
 810                     assert!(!volatile);
 811                     assert!(!alignstack);
 812
 813                     assert_eq!(inputs.len(), 2);
 814                     let leaf = codegen_operand(fx, &inputs[0].1).load_scalar(fx); // %eax
 815                     let subleaf = codegen_operand(fx, &inputs[1].1).load_scalar(fx); // %ecx
 816
 817                     let (eax, ebx, ecx, edx) =
 818                         crate::intrinsics::codegen_cpuid_call(fx, leaf, subleaf);
 819
 820                     assert_eq!(outputs.len(), 4);
 821                     codegen_place(fx, outputs[0])
 822                         .write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
 823                     codegen_place(fx, outputs[1])
 824                         .write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
 825                     codegen_place(fx, outputs[2])
 826                         .write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
 827                     codegen_place(fx, outputs[3])
 828                         .write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
 829                 }
 830                 "xgetbv" => {
 831                     assert_eq!(input_names, &[Symbol::intern("{ecx}")]);
 832
 833                     assert_eq!(output_names.len(), 2);
 834                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 835                         assert_eq!(&output_names[i].constraint.as_str(), c);
 836                         assert!(!output_names[i].is_rw);
 837                         assert!(!output_names[i].is_indirect);
 838                     }
 839
 840                     assert_eq!(clobbers, &[]);
 841
 842                     assert!(!volatile);
 843                     assert!(!alignstack);
 844
 845                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 846                 }
 847                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 848                 _ if fx
 849                     .tcx
 850                     .symbol_name(fx.instance)
 851                     .name
 852                     .starts_with("___chkstk") =>
 853                 {
 854                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 855                 }
 856                 _ if fx.tcx.symbol_name(fx.instance).name == "__alloca" => {
 857                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 858                 }
 859                 // Used in sys::windows::abort_internal
 860                 "int $$0x29" => {
 861                     crate::trap::trap_unimplemented(fx, "Windows abort");
 862                 }
 863                 _ => fx
 864                     .tcx
 865                     .sess
 866                     .span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 867             }
 868         }
 869         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 870     }
 871 }
 872
 873 fn codegen_array_len<'tcx>(
 874     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 875     place: CPlace<'tcx>,
 876 ) -> Value {
 877     match *place.layout().ty.kind() {
 878         ty::Array(_elem_ty, len) => {
 879             let len = fx
 880                 .monomorphize(&len)
 881                 .eval(fx.tcx, ParamEnv::reveal_all())
 882                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 883             fx.bcx.ins().iconst(fx.pointer_type, len)
 884         }
 885         ty::Slice(_elem_ty) => place
 886             .to_ptr_maybe_unsized()
 887             .1
 888             .expect("Length metadata for slice place"),
 889         _ => bug!("Rvalue::Len({:?})", place),
 890     }
 891 }
 892
 893 pub(crate) fn codegen_place<'tcx>(
 894     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 895     place: Place<'tcx>,
 896 ) -> CPlace<'tcx> {
 897     let mut cplace = fx.get_local_place(place.local);
 898
 899     for elem in place.projection {
 900         match elem {
 901             PlaceElem::Deref => {
 902                 cplace = cplace.place_deref(fx);
 903             }
 904             PlaceElem::Field(field, _ty) => {
 905                 cplace = cplace.place_field(fx, field);
 906             }
 907             PlaceElem::Index(local) => {
 908                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 909                 cplace = cplace.place_index(fx, index);
 910             }
 911             PlaceElem::ConstantIndex {
 912                 offset,
 913                 min_length: _,
 914                 from_end,
 915             } => {
 916                 let offset: u64 = offset;
 917                 let index = if !from_end {
 918                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 919                 } else {
 920                     let len = codegen_array_len(fx, cplace);
 921                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 922                 };
 923                 cplace = cplace.place_index(fx, index);
 924             }
 925             PlaceElem::Subslice { from, to, from_end } => {
 926                 // These indices are generated by slice patterns.
 927                 // slice[from:-to] in Python terms.
 928
 929                 let from: u64 = from;
 930                 let to: u64 = to;
 931
 932                 match cplace.layout().ty.kind() {
 933                     ty::Array(elem_ty, _len) => {
 934                         assert!(!from_end, "array subslices are never `from_end`");
 935                         let elem_layout = fx.layout_of(elem_ty);
 936                         let ptr = cplace.to_ptr();
 937                         cplace = CPlace::for_ptr(
 938                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 939                             fx.layout_of(fx.tcx.mk_array(elem_ty, to - from)),
 940                         );
 941                     }
 942                     ty::Slice(elem_ty) => {
 943                         assert!(from_end, "slice subslices should be `from_end`");
 944                         let elem_layout = fx.layout_of(elem_ty);
 945                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 946                         let len = len.unwrap();
 947                         cplace = CPlace::for_ptr_with_extra(
 948                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 949                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 950                             cplace.layout(),
 951                         );
 952                     }
 953                     _ => unreachable!(),
 954                 }
 955             }
 956             PlaceElem::Downcast(_adt_def, variant) => {
 957                 cplace = cplace.downcast_variant(fx, variant);
 958             }
 959         }
 960     }
 961
 962     cplace
 963 }
 964
 965 pub(crate) fn codegen_operand<'tcx>(
 966     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 967     operand: &Operand<'tcx>,
 968 ) -> CValue<'tcx> {
 969     match operand {
 970         Operand::Move(place) | Operand::Copy(place) => {
 971             let cplace = codegen_place(fx, *place);
 972             cplace.to_cvalue(fx)
 973         }
 974         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 975     }
 976 }
 977
 978 pub(crate) fn codegen_panic<'tcx>(
 979     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 980     msg_str: &str,
 981     span: Span,
 982 ) {
 983     let location = fx.get_caller_location(span).load_scalar(fx);
 984
 985     let msg_ptr = fx.anonymous_str("assert", msg_str);
 986     let msg_len = fx
 987         .bcx
 988         .ins()
 989         .iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 990     let args = [msg_ptr, msg_len, location];
 991
 992     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, span);
 993 }
 994
 995 pub(crate) fn codegen_panic_inner<'tcx>(
 996     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 997     lang_item: rustc_hir::LangItem,
 998     args: &[Value],
 999     span: Span,
1000 ) {
1001     let def_id = fx
1002         .tcx
1003         .lang_items()
1004         .require(lang_item)
1005         .unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
1006
1007     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
1008     let symbol_name = fx.tcx.symbol_name(instance).name;
1009
1010     fx.lib_call(
1011         &*symbol_name,
1012         vec![fx.pointer_type, fx.pointer_type, fx.pointer_type],
1013         vec![],
1014         args,
1015     );
1016
1017     crate::trap::trap_unreachable(fx, "panic lang item returned");
1018 }