compiler/rustc_codegen_cranelift/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 _inst_guard =
  16         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  17     debug_assert!(!instance.substs.needs_infer());
  18
  19     let mir = tcx.instance_mir(instance.def);
  20
  21     // Declare function
  22     let (name, sig) = get_function_name_and_sig(tcx, cx.module.isa().triple(), instance, false);
  23     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  24
  25     cx.cached_context.clear();
  26
  27     // Make the FunctionBuilder
  28     let mut func_ctx = FunctionBuilderContext::new();
  29     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  30     func.name = ExternalName::user(0, func_id.as_u32());
  31     func.signature = sig;
  32     func.collect_debug_info();
  33
  34     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  35
  36     // Predefine blocks
  37     let start_block = bcx.create_block();
  38     let block_map: IndexVec<BasicBlock, Block> = (0..mir.basic_blocks().len())
  39         .map(|_| bcx.create_block())
  40         .collect();
  41
  42     // Make FunctionCx
  43     let pointer_type = cx.module.target_config().pointer_type();
  44     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  45
  46     let mut fx = FunctionCx {
  47         cx,
  48         tcx,
  49         pointer_type,
  50
  51         instance,
  52         mir,
  53
  54         bcx,
  55         block_map,
  56         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  57         caller_location: None, // set by `codegen_fn_prelude`
  58         cold_blocks: EntitySet::new(),
  59
  60         clif_comments,
  61         source_info_set: indexmap::IndexSet::new(),
  62         next_ssa_var: 0,
  63
  64         inline_asm_index: 0,
  65     };
  66
  67     let arg_uninhabited = fx.mir.args_iter().any(|arg| {
  68         fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty))
  69             .abi
  70             .is_uninhabited()
  71     });
  72
  73     if arg_uninhabited {
  74         fx.bcx
  75             .append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  76         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  77         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  78     } else {
  79         tcx.sess.time("codegen clif ir", || {
  80             tcx.sess.time("codegen prelude", || {
  81                 crate::abi::codegen_fn_prelude(&mut fx, start_block)
  82             });
  83             codegen_fn_content(&mut fx);
  84         });
  85     }
  86
  87     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  88     let instance = fx.instance;
  89     let mut clif_comments = fx.clif_comments;
  90     let source_info_set = fx.source_info_set;
  91     let local_map = fx.local_map;
  92     let cold_blocks = fx.cold_blocks;
  93
  94     // Store function in context
  95     let context = &mut cx.cached_context;
  96     context.func = func;
  97
  98     crate::pretty_clif::write_clif_file(tcx, "unopt", None, instance, &context, &clif_comments);
  99
 100     // Verify function
 101     verify_func(tcx, &clif_comments, &context.func);
 102
 103     // Perform rust specific optimizations
 104     tcx.sess.time("optimize clif ir", || {
 105         crate::optimize::optimize_function(
 106             tcx,
 107             instance,
 108             context,
 109             &cold_blocks,
 110             &mut clif_comments,
 111         );
 112     });
 113
 114     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 115     // instruction, which doesn't have an encoding.
 116     context.compute_cfg();
 117     context.compute_domtree();
 118     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 119     context.dce(cx.module.isa()).unwrap();
 120
 121     // Define function
 122     let module = &mut cx.module;
 123     tcx.sess.time("define function", || {
 124         module
 125             .define_function(
 126                 func_id,
 127                 context,
 128                 &mut cranelift_codegen::binemit::NullTrapSink {},
 129             )
 130             .unwrap()
 131     });
 132
 133     // Write optimized function to file for debugging
 134     crate::pretty_clif::write_clif_file(
 135         tcx,
 136         "opt",
 137         Some(cx.module.isa()),
 138         instance,
 139         &context,
 140         &clif_comments,
 141     );
 142
 143     // Define debuginfo for function
 144     let isa = cx.module.isa();
 145     let debug_context = &mut cx.debug_context;
 146     let unwind_context = &mut cx.unwind_context;
 147     tcx.sess.time("generate debug info", || {
 148         if let Some(debug_context) = debug_context {
 149             debug_context.define_function(
 150                 instance,
 151                 func_id,
 152                 &name,
 153                 isa,
 154                 context,
 155                 &source_info_set,
 156                 local_map,
 157             );
 158         }
 159         unwind_context.add_function(func_id, &context, isa);
 160     });
 161
 162     // Clear context to make it usable for the next function
 163     context.clear();
 164 }
 165
 166 pub(crate) fn verify_func(
 167     tcx: TyCtxt<'_>,
 168     writer: &crate::pretty_clif::CommentWriter,
 169     func: &Function,
 170 ) {
 171     tcx.sess.time("verify clif ir", || {
 172         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 173         match cranelift_codegen::verify_function(&func, &flags) {
 174             Ok(_) => {}
 175             Err(err) => {
 176                 tcx.sess.err(&format!("{:?}", err));
 177                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 178                     &func,
 179                     None,
 180                     Some(Box::new(writer)),
 181                     err,
 182                 );
 183                 tcx.sess
 184                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 185             }
 186         }
 187     });
 188 }
 189
 190 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Module>) {
 191     crate::constant::check_constants(fx);
 192
 193     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 194         let block = fx.get_block(bb);
 195         fx.bcx.switch_to_block(block);
 196
 197         if bb_data.is_cleanup {
 198             // Unwinding after panicking is not supported
 199             continue;
 200
 201             // FIXME once unwinding is supported uncomment next lines
 202             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 203             // fx.cold_blocks.insert(block);
 204         }
 205
 206         fx.bcx.ins().nop();
 207         for stmt in &bb_data.statements {
 208             fx.set_debug_loc(stmt.source_info);
 209             codegen_stmt(fx, block, stmt);
 210         }
 211
 212         #[cfg(debug_assertions)]
 213         {
 214             let mut terminator_head = "\n".to_string();
 215             bb_data
 216                 .terminator()
 217                 .kind
 218                 .fmt_head(&mut terminator_head)
 219                 .unwrap();
 220             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 221             fx.add_comment(inst, terminator_head);
 222         }
 223
 224         fx.set_debug_loc(bb_data.terminator().source_info);
 225
 226         match &bb_data.terminator().kind {
 227             TerminatorKind::Goto { target } => {
 228                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 229                     let mut can_immediately_return = true;
 230                     for stmt in &fx.mir[*target].statements {
 231                         if let StatementKind::StorageDead(_) = stmt.kind {
 232                         } else {
 233                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 234                             can_immediately_return = false;
 235                             break;
 236                         }
 237                     }
 238
 239                     if can_immediately_return {
 240                         crate::abi::codegen_return(fx);
 241                         continue;
 242                     }
 243                 }
 244
 245                 let block = fx.get_block(*target);
 246                 fx.bcx.ins().jump(block, &[]);
 247             }
 248             TerminatorKind::Return => {
 249                 crate::abi::codegen_return(fx);
 250             }
 251             TerminatorKind::Assert {
 252                 cond,
 253                 expected,
 254                 msg,
 255                 target,
 256                 cleanup: _,
 257             } => {
 258                 if !fx.tcx.sess.overflow_checks() {
 259                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 260                         let target = fx.get_block(*target);
 261                         fx.bcx.ins().jump(target, &[]);
 262                         continue;
 263                     }
 264                 }
 265                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 266
 267                 let target = fx.get_block(*target);
 268                 let failure = fx.bcx.create_block();
 269                 fx.cold_blocks.insert(failure);
 270
 271                 if *expected {
 272                     fx.bcx.ins().brz(cond, failure, &[]);
 273                 } else {
 274                     fx.bcx.ins().brnz(cond, failure, &[]);
 275                 };
 276                 fx.bcx.ins().jump(target, &[]);
 277
 278                 fx.bcx.switch_to_block(failure);
 279                 fx.bcx.ins().nop();
 280
 281                 match msg {
 282                     AssertKind::BoundsCheck { ref len, ref index } => {
 283                         let len = codegen_operand(fx, len).load_scalar(fx);
 284                         let index = codegen_operand(fx, index).load_scalar(fx);
 285                         let location = fx
 286                             .get_caller_location(bb_data.terminator().source_info.span)
 287                             .load_scalar(fx);
 288
 289                         codegen_panic_inner(
 290                             fx,
 291                             rustc_hir::LangItem::PanicBoundsCheck,
 292                             &[index, len, location],
 293                             bb_data.terminator().source_info.span,
 294                         );
 295                     }
 296                     _ => {
 297                         let msg_str = msg.description();
 298                         codegen_panic(fx, msg_str, bb_data.terminator().source_info.span);
 299                     }
 300                 }
 301             }
 302
 303             TerminatorKind::SwitchInt {
 304                 discr,
 305                 switch_ty,
 306                 targets,
 307             } => {
 308                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 309
 310                 if switch_ty.kind() == fx.tcx.types.bool.kind() {
 311                     assert_eq!(targets.iter().count(), 1);
 312                     let (then_value, then_block) = targets.iter().next().unwrap();
 313                     let then_block = fx.get_block(then_block);
 314                     let else_block = fx.get_block(targets.otherwise());
 315                     let test_zero = match then_value {
 316                         0 => true,
 317                         1 => false,
 318                         _ => unreachable!("{:?}", targets),
 319                     };
 320
 321                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 322                     let (discr, is_inverted) =
 323                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 324                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 325                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 326                     let discr =
 327                         crate::optimize::peephole::make_branchable_value(&mut fx.bcx, discr);
 328                     if test_zero {
 329                         fx.bcx.ins().brz(discr, then_block, &[]);
 330                         fx.bcx.ins().jump(else_block, &[]);
 331                     } else {
 332                         fx.bcx.ins().brnz(discr, then_block, &[]);
 333                         fx.bcx.ins().jump(else_block, &[]);
 334                     }
 335                 } else {
 336                     let mut switch = ::cranelift_frontend::Switch::new();
 337                     for (value, block) in targets.iter() {
 338                         let block = fx.get_block(block);
 339                         switch.set_entry(value, block);
 340                     }
 341                     let otherwise_block = fx.get_block(targets.otherwise());
 342                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 343                 }
 344             }
 345             TerminatorKind::Call {
 346                 func,
 347                 args,
 348                 destination,
 349                 fn_span,
 350                 cleanup: _,
 351                 from_hir_call: _,
 352             } => {
 353                 fx.tcx.sess.time("codegen call", || {
 354                     crate::abi::codegen_terminator_call(
 355                         fx,
 356                         *fn_span,
 357                         block,
 358                         func,
 359                         args,
 360                         *destination,
 361                     )
 362                 });
 363             }
 364             TerminatorKind::InlineAsm {
 365                 template,
 366                 operands,
 367                 options,
 368                 destination,
 369                 line_spans: _,
 370             } => {
 371                 crate::inline_asm::codegen_inline_asm(
 372                     fx,
 373                     bb_data.terminator().source_info.span,
 374                     template,
 375                     operands,
 376                     *options,
 377                 );
 378
 379                 match *destination {
 380                     Some(destination) => {
 381                         let destination_block = fx.get_block(destination);
 382                         fx.bcx.ins().jump(destination_block, &[]);
 383                     }
 384                     None => {
 385                         crate::trap::trap_unreachable(
 386                             fx,
 387                             "[corruption] Returned from noreturn inline asm",
 388                         );
 389                     }
 390                 }
 391             }
 392             TerminatorKind::Resume | TerminatorKind::Abort => {
 393                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 394             }
 395             TerminatorKind::Unreachable => {
 396                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 397             }
 398             TerminatorKind::Yield { .. }
 399             | TerminatorKind::FalseEdge { .. }
 400             | TerminatorKind::FalseUnwind { .. }
 401             | TerminatorKind::DropAndReplace { .. }
 402             | TerminatorKind::GeneratorDrop => {
 403                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 404             }
 405             TerminatorKind::Drop {
 406                 place,
 407                 target,
 408                 unwind: _,
 409             } => {
 410                 let drop_place = codegen_place(fx, *place);
 411                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 412
 413                 let target_block = fx.get_block(*target);
 414                 fx.bcx.ins().jump(target_block, &[]);
 415             }
 416         };
 417     }
 418
 419     fx.bcx.seal_all_blocks();
 420     fx.bcx.finalize();
 421 }
 422
 423 fn codegen_stmt<'tcx>(
 424     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 425     #[allow(unused_variables)] cur_block: Block,
 426     stmt: &Statement<'tcx>,
 427 ) {
 428     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 429
 430     fx.set_debug_loc(stmt.source_info);
 431
 432     #[cfg(false_debug_assertions)]
 433     match &stmt.kind {
 434         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 435         _ => {
 436             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 437             fx.add_comment(inst, format!("{:?}", stmt));
 438         }
 439     }
 440
 441     match &stmt.kind {
 442         StatementKind::SetDiscriminant {
 443             place,
 444             variant_index,
 445         } => {
 446             let place = codegen_place(fx, **place);
 447             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 448         }
 449         StatementKind::Assign(to_place_and_rval) => {
 450             let lval = codegen_place(fx, to_place_and_rval.0);
 451             let dest_layout = lval.layout();
 452             match to_place_and_rval.1 {
 453                 Rvalue::Use(ref operand) => {
 454                     let val = codegen_operand(fx, operand);
 455                     lval.write_cvalue(fx, val);
 456                 }
 457                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 458                     let place = codegen_place(fx, place);
 459                     let ref_ = place.place_ref(fx, lval.layout());
 460                     lval.write_cvalue(fx, ref_);
 461                 }
 462                 Rvalue::ThreadLocalRef(def_id) => {
 463                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 464                     lval.write_cvalue(fx, val);
 465                 }
 466                 Rvalue::BinaryOp(bin_op, ref lhs, ref rhs) => {
 467                     let lhs = codegen_operand(fx, lhs);
 468                     let rhs = codegen_operand(fx, rhs);
 469
 470                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 471                     lval.write_cvalue(fx, res);
 472                 }
 473                 Rvalue::CheckedBinaryOp(bin_op, ref lhs, ref rhs) => {
 474                     let lhs = codegen_operand(fx, lhs);
 475                     let rhs = codegen_operand(fx, rhs);
 476
 477                     let res = if !fx.tcx.sess.overflow_checks() {
 478                         let val =
 479                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 480                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 481                         CValue::by_val_pair(val, is_overflow, lval.layout())
 482                     } else {
 483                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 484                     };
 485
 486                     lval.write_cvalue(fx, res);
 487                 }
 488                 Rvalue::UnaryOp(un_op, ref operand) => {
 489                     let operand = codegen_operand(fx, operand);
 490                     let layout = operand.layout();
 491                     let val = operand.load_scalar(fx);
 492                     let res = match un_op {
 493                         UnOp::Not => match layout.ty.kind() {
 494                             ty::Bool => {
 495                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 496                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 497                             }
 498                             ty::Uint(_) | ty::Int(_) => {
 499                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 500                             }
 501                             _ => unreachable!("un op Not for {:?}", layout.ty),
 502                         },
 503                         UnOp::Neg => match layout.ty.kind() {
 504                             ty::Int(IntTy::I128) => {
 505                                 // FIXME remove this case once ineg.i128 works
 506                                 let zero =
 507                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 508                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 509                             }
 510                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 511                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 512                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 513                         },
 514                     };
 515                     lval.write_cvalue(fx, res);
 516                 }
 517                 Rvalue::Cast(
 518                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 519                     ref operand,
 520                     to_ty,
 521                 ) => {
 522                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 523                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 524                     match *from_ty.kind() {
 525                         ty::FnDef(def_id, substs) => {
 526                             let func_ref = fx.get_function_ref(
 527                                 Instance::resolve_for_fn_ptr(
 528                                     fx.tcx,
 529                                     ParamEnv::reveal_all(),
 530                                     def_id,
 531                                     substs,
 532                                 )
 533                                 .unwrap()
 534                                 .polymorphize(fx.tcx),
 535                             );
 536                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 537                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 538                         }
 539                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 540                     }
 541                 }
 542                 Rvalue::Cast(
 543                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 544                     ref operand,
 545                     to_ty,
 546                 )
 547                 | Rvalue::Cast(
 548                     CastKind::Pointer(PointerCast::MutToConstPointer),
 549                     ref operand,
 550                     to_ty,
 551                 )
 552                 | Rvalue::Cast(
 553                     CastKind::Pointer(PointerCast::ArrayToPointer),
 554                     ref operand,
 555                     to_ty,
 556                 ) => {
 557                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 558                     let operand = codegen_operand(fx, operand);
 559                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 560                 }
 561                 Rvalue::Cast(CastKind::Misc, ref operand, to_ty) => {
 562                     let operand = codegen_operand(fx, operand);
 563                     let from_ty = operand.layout().ty;
 564                     let to_ty = fx.monomorphize(to_ty);
 565
 566                     fn is_fat_ptr<'tcx>(
 567                         fx: &FunctionCx<'_, 'tcx, impl Module>,
 568                         ty: Ty<'tcx>,
 569                     ) -> bool {
 570                         ty.builtin_deref(true)
 571                             .map(
 572                                 |ty::TypeAndMut {
 573                                      ty: pointee_ty,
 574                                      mutbl: _,
 575                                  }| {
 576                                     has_ptr_meta(fx.tcx, pointee_ty)
 577                                 },
 578                             )
 579                             .unwrap_or(false)
 580                     }
 581
 582                     if is_fat_ptr(fx, from_ty) {
 583                         if is_fat_ptr(fx, to_ty) {
 584                             // fat-ptr -> fat-ptr
 585                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 586                         } else {
 587                             // fat-ptr -> thin-ptr
 588                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 589                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 590                         }
 591                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 592                         // enum -> discriminant value
 593                         assert!(adt_def.is_enum());
 594                         match to_ty.kind() {
 595                             ty::Uint(_) | ty::Int(_) => {}
 596                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 597                         }
 598
 599                         use rustc_target::abi::{Int, TagEncoding, Variants};
 600
 601                         match operand.layout().variants {
 602                             Variants::Single { index } => {
 603                                 let discr = operand
 604                                     .layout()
 605                                     .ty
 606                                     .discriminant_for_variant(fx.tcx, index)
 607                                     .unwrap();
 608                                 let discr = if discr.ty.is_signed() {
 609                                     fx.layout_of(discr.ty).size.sign_extend(discr.val)
 610                                 } else {
 611                                     discr.val
 612                                 };
 613                                 let discr = discr.into();
 614
 615                                 let discr = CValue::const_val(fx, fx.layout_of(to_ty), discr);
 616                                 lval.write_cvalue(fx, discr);
 617                             }
 618                             Variants::Multiple {
 619                                 ref tag,
 620                                 tag_field,
 621                                 tag_encoding: TagEncoding::Direct,
 622                                 variants: _,
 623                             } => {
 624                                 let cast_to = fx.clif_type(dest_layout.ty).unwrap();
 625
 626                                 // Read the tag/niche-encoded discriminant from memory.
 627                                 let encoded_discr =
 628                                     operand.value_field(fx, mir::Field::new(tag_field));
 629                                 let encoded_discr = encoded_discr.load_scalar(fx);
 630
 631                                 // Decode the discriminant (specifically if it's niche-encoded).
 632                                 let signed = match tag.value {
 633                                     Int(_, signed) => signed,
 634                                     _ => false,
 635                                 };
 636                                 let val = clif_intcast(fx, encoded_discr, cast_to, signed);
 637                                 let val = CValue::by_val(val, dest_layout);
 638                                 lval.write_cvalue(fx, val);
 639                             }
 640                             Variants::Multiple { .. } => unreachable!(),
 641                         }
 642                     } else {
 643                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 644                         let from = operand.load_scalar(fx);
 645
 646                         let res = clif_int_or_float_cast(
 647                             fx,
 648                             from,
 649                             type_sign(from_ty),
 650                             to_clif_ty,
 651                             type_sign(to_ty),
 652                         );
 653                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 654                     }
 655                 }
 656                 Rvalue::Cast(
 657                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 658                     ref operand,
 659                     _to_ty,
 660                 ) => {
 661                     let operand = codegen_operand(fx, operand);
 662                     match *operand.layout().ty.kind() {
 663                         ty::Closure(def_id, substs) => {
 664                             let instance = Instance::resolve_closure(
 665                                 fx.tcx,
 666                                 def_id,
 667                                 substs,
 668                                 ty::ClosureKind::FnOnce,
 669                             )
 670                             .polymorphize(fx.tcx);
 671                             let func_ref = fx.get_function_ref(instance);
 672                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 673                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 674                         }
 675                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 676                     }
 677                 }
 678                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 679                     let operand = codegen_operand(fx, operand);
 680                     operand.unsize_value(fx, lval);
 681                 }
 682                 Rvalue::Discriminant(place) => {
 683                     let place = codegen_place(fx, place);
 684                     let value = place.to_cvalue(fx);
 685                     let discr =
 686                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 687                     lval.write_cvalue(fx, discr);
 688                 }
 689                 Rvalue::Repeat(ref operand, times) => {
 690                     let operand = codegen_operand(fx, operand);
 691                     let times = fx
 692                         .monomorphize(times)
 693                         .eval(fx.tcx, ParamEnv::reveal_all())
 694                         .val
 695                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 696                         .unwrap();
 697                     if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 698                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 699                         // FIXME use emit_small_memset where possible
 700                         let addr = lval.to_ptr().get_addr(fx);
 701                         let val = operand.load_scalar(fx);
 702                         fx.bcx
 703                             .call_memset(fx.cx.module.target_config(), addr, val, times);
 704                     } else {
 705                         let loop_block = fx.bcx.create_block();
 706                         let loop_block2 = fx.bcx.create_block();
 707                         let done_block = fx.bcx.create_block();
 708                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 709                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 710                         fx.bcx.ins().jump(loop_block, &[zero]);
 711
 712                         fx.bcx.switch_to_block(loop_block);
 713                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 714                         fx.bcx.ins().brnz(done, done_block, &[]);
 715                         fx.bcx.ins().jump(loop_block2, &[]);
 716
 717                         fx.bcx.switch_to_block(loop_block2);
 718                         let to = lval.place_index(fx, index);
 719                         to.write_cvalue(fx, operand);
 720                         let index = fx.bcx.ins().iadd_imm(index, 1);
 721                         fx.bcx.ins().jump(loop_block, &[index]);
 722
 723                         fx.bcx.switch_to_block(done_block);
 724                         fx.bcx.ins().nop();
 725                     }
 726                 }
 727                 Rvalue::Len(place) => {
 728                     let place = codegen_place(fx, place);
 729                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 730                     let len = codegen_array_len(fx, place);
 731                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 732                 }
 733                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 734                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 735                     let content_ty = fx.monomorphize(content_ty);
 736                     let layout = fx.layout_of(content_ty);
 737                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 738                     let llalign = fx
 739                         .bcx
 740                         .ins()
 741                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 742                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 743
 744                     // Allocate space:
 745                     let def_id = match fx
 746                         .tcx
 747                         .lang_items()
 748                         .require(rustc_hir::LangItem::ExchangeMalloc)
 749                     {
 750                         Ok(id) => id,
 751                         Err(s) => {
 752                             fx.tcx
 753                                 .sess
 754                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 755                         }
 756                     };
 757                     let instance = ty::Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 758                     let func_ref = fx.get_function_ref(instance);
 759                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 760                     let ptr = fx.bcx.inst_results(call)[0];
 761                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 762                 }
 763                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 764                     assert!(lval
 765                         .layout()
 766                         .ty
 767                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 768                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 769                     let val =
 770                         CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 771                     lval.write_cvalue(fx, val);
 772                 }
 773                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 774                     AggregateKind::Array(_ty) => {
 775                         for (i, operand) in operands.iter().enumerate() {
 776                             let operand = codegen_operand(fx, operand);
 777                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 778                             let to = lval.place_index(fx, index);
 779                             to.write_cvalue(fx, operand);
 780                         }
 781                     }
 782                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 783                 },
 784             }
 785         }
 786         StatementKind::StorageLive(_)
 787         | StatementKind::StorageDead(_)
 788         | StatementKind::Nop
 789         | StatementKind::FakeRead(..)
 790         | StatementKind::Retag { .. }
 791         | StatementKind::AscribeUserType(..) => {}
 792
 793         StatementKind::LlvmInlineAsm(asm) => {
 794             use rustc_span::symbol::Symbol;
 795             let LlvmInlineAsm {
 796                 asm,
 797                 outputs,
 798                 inputs,
 799             } = &**asm;
 800             let rustc_hir::LlvmInlineAsmInner {
 801                 asm: asm_code,         // Name
 802                 outputs: output_names, // Vec<LlvmInlineAsmOutput>
 803                 inputs: input_names,   // Vec<Name>
 804                 clobbers,              // Vec<Name>
 805                 volatile,              // bool
 806                 alignstack,            // bool
 807                 dialect: _,
 808                 asm_str_style: _,
 809             } = asm;
 810             match asm_code.as_str().trim() {
 811                 "" => {
 812                     // Black box
 813                 }
 814                 "mov %rbx, %rsi\n                  cpuid\n                  xchg %rbx, %rsi" => {
 815                     assert_eq!(
 816                         input_names,
 817                         &[Symbol::intern("{eax}"), Symbol::intern("{ecx}")]
 818                     );
 819                     assert_eq!(output_names.len(), 4);
 820                     for (i, c) in (&["={eax}", "={esi}", "={ecx}", "={edx}"])
 821                         .iter()
 822                         .enumerate()
 823                     {
 824                         assert_eq!(&output_names[i].constraint.as_str(), c);
 825                         assert!(!output_names[i].is_rw);
 826                         assert!(!output_names[i].is_indirect);
 827                     }
 828
 829                     assert_eq!(clobbers, &[]);
 830
 831                     assert!(!volatile);
 832                     assert!(!alignstack);
 833
 834                     assert_eq!(inputs.len(), 2);
 835                     let leaf = codegen_operand(fx, &inputs[0].1).load_scalar(fx); // %eax
 836                     let subleaf = codegen_operand(fx, &inputs[1].1).load_scalar(fx); // %ecx
 837
 838                     let (eax, ebx, ecx, edx) =
 839                         crate::intrinsics::codegen_cpuid_call(fx, leaf, subleaf);
 840
 841                     assert_eq!(outputs.len(), 4);
 842                     codegen_place(fx, outputs[0])
 843                         .write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
 844                     codegen_place(fx, outputs[1])
 845                         .write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
 846                     codegen_place(fx, outputs[2])
 847                         .write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
 848                     codegen_place(fx, outputs[3])
 849                         .write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
 850                 }
 851                 "xgetbv" => {
 852                     assert_eq!(input_names, &[Symbol::intern("{ecx}")]);
 853
 854                     assert_eq!(output_names.len(), 2);
 855                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 856                         assert_eq!(&output_names[i].constraint.as_str(), c);
 857                         assert!(!output_names[i].is_rw);
 858                         assert!(!output_names[i].is_indirect);
 859                     }
 860
 861                     assert_eq!(clobbers, &[]);
 862
 863                     assert!(!volatile);
 864                     assert!(!alignstack);
 865
 866                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 867                 }
 868                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 869                 _ if fx
 870                     .tcx
 871                     .symbol_name(fx.instance)
 872                     .name
 873                     .starts_with("___chkstk") =>
 874                 {
 875                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 876                 }
 877                 _ if fx.tcx.symbol_name(fx.instance).name == "__alloca" => {
 878                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 879                 }
 880                 // Used in sys::windows::abort_internal
 881                 "int $$0x29" => {
 882                     crate::trap::trap_unimplemented(fx, "Windows abort");
 883                 }
 884                 _ => fx
 885                     .tcx
 886                     .sess
 887                     .span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 888             }
 889         }
 890         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 891     }
 892 }
 893
 894 fn codegen_array_len<'tcx>(
 895     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 896     place: CPlace<'tcx>,
 897 ) -> Value {
 898     match *place.layout().ty.kind() {
 899         ty::Array(_elem_ty, len) => {
 900             let len = fx
 901                 .monomorphize(len)
 902                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 903             fx.bcx.ins().iconst(fx.pointer_type, len)
 904         }
 905         ty::Slice(_elem_ty) => place
 906             .to_ptr_maybe_unsized()
 907             .1
 908             .expect("Length metadata for slice place"),
 909         _ => bug!("Rvalue::Len({:?})", place),
 910     }
 911 }
 912
 913 pub(crate) fn codegen_place<'tcx>(
 914     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 915     place: Place<'tcx>,
 916 ) -> CPlace<'tcx> {
 917     let mut cplace = fx.get_local_place(place.local);
 918
 919     for elem in place.projection {
 920         match elem {
 921             PlaceElem::Deref => {
 922                 cplace = cplace.place_deref(fx);
 923             }
 924             PlaceElem::Field(field, _ty) => {
 925                 cplace = cplace.place_field(fx, field);
 926             }
 927             PlaceElem::Index(local) => {
 928                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 929                 cplace = cplace.place_index(fx, index);
 930             }
 931             PlaceElem::ConstantIndex {
 932                 offset,
 933                 min_length: _,
 934                 from_end,
 935             } => {
 936                 let offset: u64 = offset;
 937                 let index = if !from_end {
 938                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 939                 } else {
 940                     let len = codegen_array_len(fx, cplace);
 941                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 942                 };
 943                 cplace = cplace.place_index(fx, index);
 944             }
 945             PlaceElem::Subslice { from, to, from_end } => {
 946                 // These indices are generated by slice patterns.
 947                 // slice[from:-to] in Python terms.
 948
 949                 let from: u64 = from;
 950                 let to: u64 = to;
 951
 952                 match cplace.layout().ty.kind() {
 953                     ty::Array(elem_ty, _len) => {
 954                         assert!(!from_end, "array subslices are never `from_end`");
 955                         let elem_layout = fx.layout_of(elem_ty);
 956                         let ptr = cplace.to_ptr();
 957                         cplace = CPlace::for_ptr(
 958                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 959                             fx.layout_of(fx.tcx.mk_array(elem_ty, to - from)),
 960                         );
 961                     }
 962                     ty::Slice(elem_ty) => {
 963                         assert!(from_end, "slice subslices should be `from_end`");
 964                         let elem_layout = fx.layout_of(elem_ty);
 965                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 966                         let len = len.unwrap();
 967                         cplace = CPlace::for_ptr_with_extra(
 968                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 969                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 970                             cplace.layout(),
 971                         );
 972                     }
 973                     _ => unreachable!(),
 974                 }
 975             }
 976             PlaceElem::Downcast(_adt_def, variant) => {
 977                 cplace = cplace.downcast_variant(fx, variant);
 978             }
 979         }
 980     }
 981
 982     cplace
 983 }
 984
 985 pub(crate) fn codegen_operand<'tcx>(
 986     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 987     operand: &Operand<'tcx>,
 988 ) -> CValue<'tcx> {
 989     match operand {
 990         Operand::Move(place) | Operand::Copy(place) => {
 991             let cplace = codegen_place(fx, *place);
 992             cplace.to_cvalue(fx)
 993         }
 994         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 995     }
 996 }
 997
 998 pub(crate) fn codegen_panic<'tcx>(
 999     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
1000     msg_str: &str,
1001     span: Span,
1002 ) {
1003     let location = fx.get_caller_location(span).load_scalar(fx);
1004
1005     let msg_ptr = fx.anonymous_str("assert", msg_str);
1006     let msg_len = fx
1007         .bcx
1008         .ins()
1009         .iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
1010     let args = [msg_ptr, msg_len, location];
1011
1012     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, span);
1013 }
1014
1015 pub(crate) fn codegen_panic_inner<'tcx>(
1016     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
1017     lang_item: rustc_hir::LangItem,
1018     args: &[Value],
1019     span: Span,
1020 ) {
1021     let def_id = fx
1022         .tcx
1023         .lang_items()
1024         .require(lang_item)
1025         .unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
1026
1027     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
1028     let symbol_name = fx.tcx.symbol_name(instance).name;
1029
1030     fx.lib_call(
1031         &*symbol_name,
1032         vec![fx.pointer_type, fx.pointer_type, fx.pointer_type],
1033         vec![],
1034         args,
1035     );
1036
1037     crate::trap::trap_unreachable(fx, "panic lang item returned");
1038 }