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     context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 122
 123     // Define function
 124     let module = &mut cx.module;
 125     tcx.sess.time("define function", || {
 126         module
 127             .define_function(
 128                 func_id,
 129                 context,
 130                 &mut cranelift_codegen::binemit::NullTrapSink {},
 131             )
 132             .unwrap()
 133     });
 134
 135     // Write optimized function to file for debugging
 136     crate::pretty_clif::write_clif_file(
 137         tcx,
 138         "opt",
 139         Some(cx.module.isa()),
 140         instance,
 141         &context,
 142         &clif_comments,
 143     );
 144
 145     if let Some(mach_compile_result) = &context.mach_compile_result {
 146         if let Some(disasm) = &mach_compile_result.disasm {
 147             crate::pretty_clif::write_ir_file(
 148                 tcx,
 149                 &format!("{}.vcode", tcx.symbol_name(instance).name),
 150                 |file| file.write_all(disasm.as_bytes()),
 151             )
 152         }
 153     }
 154
 155     // Define debuginfo for function
 156     let isa = cx.module.isa();
 157     let debug_context = &mut cx.debug_context;
 158     let unwind_context = &mut cx.unwind_context;
 159     tcx.sess.time("generate debug info", || {
 160         if let Some(debug_context) = debug_context {
 161             debug_context.define_function(
 162                 instance,
 163                 func_id,
 164                 &name,
 165                 isa,
 166                 context,
 167                 &source_info_set,
 168                 local_map,
 169             );
 170         }
 171         unwind_context.add_function(func_id, &context, isa);
 172     });
 173
 174     // Clear context to make it usable for the next function
 175     context.clear();
 176 }
 177
 178 pub(crate) fn verify_func(
 179     tcx: TyCtxt<'_>,
 180     writer: &crate::pretty_clif::CommentWriter,
 181     func: &Function,
 182 ) {
 183     tcx.sess.time("verify clif ir", || {
 184         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 185         match cranelift_codegen::verify_function(&func, &flags) {
 186             Ok(_) => {}
 187             Err(err) => {
 188                 tcx.sess.err(&format!("{:?}", err));
 189                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 190                     &func,
 191                     None,
 192                     Some(Box::new(writer)),
 193                     err,
 194                 );
 195                 tcx.sess
 196                     .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 197             }
 198         }
 199     });
 200 }
 201
 202 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Module>) {
 203     crate::constant::check_constants(fx);
 204
 205     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 206         let block = fx.get_block(bb);
 207         fx.bcx.switch_to_block(block);
 208
 209         if bb_data.is_cleanup {
 210             // Unwinding after panicking is not supported
 211             continue;
 212
 213             // FIXME once unwinding is supported uncomment next lines
 214             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 215             // fx.cold_blocks.insert(block);
 216         }
 217
 218         fx.bcx.ins().nop();
 219         for stmt in &bb_data.statements {
 220             fx.set_debug_loc(stmt.source_info);
 221             codegen_stmt(fx, block, stmt);
 222         }
 223
 224         #[cfg(debug_assertions)]
 225         {
 226             let mut terminator_head = "\n".to_string();
 227             bb_data
 228                 .terminator()
 229                 .kind
 230                 .fmt_head(&mut terminator_head)
 231                 .unwrap();
 232             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 233             fx.add_comment(inst, terminator_head);
 234         }
 235
 236         fx.set_debug_loc(bb_data.terminator().source_info);
 237
 238         match &bb_data.terminator().kind {
 239             TerminatorKind::Goto { target } => {
 240                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 241                     let mut can_immediately_return = true;
 242                     for stmt in &fx.mir[*target].statements {
 243                         if let StatementKind::StorageDead(_) = stmt.kind {
 244                         } else {
 245                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 246                             can_immediately_return = false;
 247                             break;
 248                         }
 249                     }
 250
 251                     if can_immediately_return {
 252                         crate::abi::codegen_return(fx);
 253                         continue;
 254                     }
 255                 }
 256
 257                 let block = fx.get_block(*target);
 258                 fx.bcx.ins().jump(block, &[]);
 259             }
 260             TerminatorKind::Return => {
 261                 crate::abi::codegen_return(fx);
 262             }
 263             TerminatorKind::Assert {
 264                 cond,
 265                 expected,
 266                 msg,
 267                 target,
 268                 cleanup: _,
 269             } => {
 270                 if !fx.tcx.sess.overflow_checks() {
 271                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 272                         let target = fx.get_block(*target);
 273                         fx.bcx.ins().jump(target, &[]);
 274                         continue;
 275                     }
 276                 }
 277                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 278
 279                 let target = fx.get_block(*target);
 280                 let failure = fx.bcx.create_block();
 281                 fx.cold_blocks.insert(failure);
 282
 283                 if *expected {
 284                     fx.bcx.ins().brz(cond, failure, &[]);
 285                 } else {
 286                     fx.bcx.ins().brnz(cond, failure, &[]);
 287                 };
 288                 fx.bcx.ins().jump(target, &[]);
 289
 290                 fx.bcx.switch_to_block(failure);
 291                 fx.bcx.ins().nop();
 292
 293                 match msg {
 294                     AssertKind::BoundsCheck { ref len, ref index } => {
 295                         let len = codegen_operand(fx, len).load_scalar(fx);
 296                         let index = codegen_operand(fx, index).load_scalar(fx);
 297                         let location = fx
 298                             .get_caller_location(bb_data.terminator().source_info.span)
 299                             .load_scalar(fx);
 300
 301                         codegen_panic_inner(
 302                             fx,
 303                             rustc_hir::LangItem::PanicBoundsCheck,
 304                             &[index, len, location],
 305                             bb_data.terminator().source_info.span,
 306                         );
 307                     }
 308                     _ => {
 309                         let msg_str = msg.description();
 310                         codegen_panic(fx, msg_str, bb_data.terminator().source_info.span);
 311                     }
 312                 }
 313             }
 314
 315             TerminatorKind::SwitchInt {
 316                 discr,
 317                 switch_ty,
 318                 targets,
 319             } => {
 320                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 321
 322                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 323                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 324                 if use_bool_opt {
 325                     assert_eq!(targets.iter().count(), 1);
 326                     let (then_value, then_block) = targets.iter().next().unwrap();
 327                     let then_block = fx.get_block(then_block);
 328                     let else_block = fx.get_block(targets.otherwise());
 329                     let test_zero = match then_value {
 330                         0 => true,
 331                         1 => false,
 332                         _ => unreachable!("{:?}", targets),
 333                     };
 334
 335                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 336                     let (discr, is_inverted) =
 337                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 338                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 339                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 340                     let discr =
 341                         crate::optimize::peephole::make_branchable_value(&mut fx.bcx, discr);
 342                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 343                         &fx.bcx, discr, test_zero,
 344                     ) {
 345                         if taken {
 346                             fx.bcx.ins().jump(then_block, &[]);
 347                         } else {
 348                             fx.bcx.ins().jump(else_block, &[]);
 349                         }
 350                     } else {
 351                         if test_zero {
 352                             fx.bcx.ins().brz(discr, then_block, &[]);
 353                             fx.bcx.ins().jump(else_block, &[]);
 354                         } else {
 355                             fx.bcx.ins().brnz(discr, then_block, &[]);
 356                             fx.bcx.ins().jump(else_block, &[]);
 357                         }
 358                     }
 359                 } else {
 360                     let mut switch = ::cranelift_frontend::Switch::new();
 361                     for (value, block) in targets.iter() {
 362                         let block = fx.get_block(block);
 363                         switch.set_entry(value, block);
 364                     }
 365                     let otherwise_block = fx.get_block(targets.otherwise());
 366                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 367                 }
 368             }
 369             TerminatorKind::Call {
 370                 func,
 371                 args,
 372                 destination,
 373                 fn_span,
 374                 cleanup: _,
 375                 from_hir_call: _,
 376             } => {
 377                 fx.tcx.sess.time("codegen call", || {
 378                     crate::abi::codegen_terminator_call(
 379                         fx,
 380                         *fn_span,
 381                         block,
 382                         func,
 383                         args,
 384                         *destination,
 385                     )
 386                 });
 387             }
 388             TerminatorKind::InlineAsm {
 389                 template,
 390                 operands,
 391                 options,
 392                 destination,
 393                 line_spans: _,
 394             } => {
 395                 crate::inline_asm::codegen_inline_asm(
 396                     fx,
 397                     bb_data.terminator().source_info.span,
 398                     template,
 399                     operands,
 400                     *options,
 401                 );
 402
 403                 match *destination {
 404                     Some(destination) => {
 405                         let destination_block = fx.get_block(destination);
 406                         fx.bcx.ins().jump(destination_block, &[]);
 407                     }
 408                     None => {
 409                         crate::trap::trap_unreachable(
 410                             fx,
 411                             "[corruption] Returned from noreturn inline asm",
 412                         );
 413                     }
 414                 }
 415             }
 416             TerminatorKind::Resume | TerminatorKind::Abort => {
 417                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 418             }
 419             TerminatorKind::Unreachable => {
 420                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 421             }
 422             TerminatorKind::Yield { .. }
 423             | TerminatorKind::FalseEdge { .. }
 424             | TerminatorKind::FalseUnwind { .. }
 425             | TerminatorKind::DropAndReplace { .. }
 426             | TerminatorKind::GeneratorDrop => {
 427                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 428             }
 429             TerminatorKind::Drop {
 430                 place,
 431                 target,
 432                 unwind: _,
 433             } => {
 434                 let drop_place = codegen_place(fx, *place);
 435                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 436
 437                 let target_block = fx.get_block(*target);
 438                 fx.bcx.ins().jump(target_block, &[]);
 439             }
 440         };
 441     }
 442
 443     fx.bcx.seal_all_blocks();
 444     fx.bcx.finalize();
 445 }
 446
 447 fn codegen_stmt<'tcx>(
 448     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 449     #[allow(unused_variables)] cur_block: Block,
 450     stmt: &Statement<'tcx>,
 451 ) {
 452     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 453
 454     fx.set_debug_loc(stmt.source_info);
 455
 456     #[cfg(false_debug_assertions)]
 457     match &stmt.kind {
 458         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 459         _ => {
 460             let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 461             fx.add_comment(inst, format!("{:?}", stmt));
 462         }
 463     }
 464
 465     match &stmt.kind {
 466         StatementKind::SetDiscriminant {
 467             place,
 468             variant_index,
 469         } => {
 470             let place = codegen_place(fx, **place);
 471             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 472         }
 473         StatementKind::Assign(to_place_and_rval) => {
 474             let lval = codegen_place(fx, to_place_and_rval.0);
 475             let dest_layout = lval.layout();
 476             match to_place_and_rval.1 {
 477                 Rvalue::Use(ref operand) => {
 478                     let val = codegen_operand(fx, operand);
 479                     lval.write_cvalue(fx, val);
 480                 }
 481                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 482                     let place = codegen_place(fx, place);
 483                     let ref_ = place.place_ref(fx, lval.layout());
 484                     lval.write_cvalue(fx, ref_);
 485                 }
 486                 Rvalue::ThreadLocalRef(def_id) => {
 487                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 488                     lval.write_cvalue(fx, val);
 489                 }
 490                 Rvalue::BinaryOp(bin_op, ref lhs, ref rhs) => {
 491                     let lhs = codegen_operand(fx, lhs);
 492                     let rhs = codegen_operand(fx, rhs);
 493
 494                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 495                     lval.write_cvalue(fx, res);
 496                 }
 497                 Rvalue::CheckedBinaryOp(bin_op, ref lhs, ref rhs) => {
 498                     let lhs = codegen_operand(fx, lhs);
 499                     let rhs = codegen_operand(fx, rhs);
 500
 501                     let res = if !fx.tcx.sess.overflow_checks() {
 502                         let val =
 503                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 504                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 505                         CValue::by_val_pair(val, is_overflow, lval.layout())
 506                     } else {
 507                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 508                     };
 509
 510                     lval.write_cvalue(fx, res);
 511                 }
 512                 Rvalue::UnaryOp(un_op, ref operand) => {
 513                     let operand = codegen_operand(fx, operand);
 514                     let layout = operand.layout();
 515                     let val = operand.load_scalar(fx);
 516                     let res = match un_op {
 517                         UnOp::Not => match layout.ty.kind() {
 518                             ty::Bool => {
 519                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 520                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 521                             }
 522                             ty::Uint(_) | ty::Int(_) => {
 523                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 524                             }
 525                             _ => unreachable!("un op Not for {:?}", layout.ty),
 526                         },
 527                         UnOp::Neg => match layout.ty.kind() {
 528                             ty::Int(IntTy::I128) => {
 529                                 // FIXME remove this case once ineg.i128 works
 530                                 let zero =
 531                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 532                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 533                             }
 534                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 535                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 536                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 537                         },
 538                     };
 539                     lval.write_cvalue(fx, res);
 540                 }
 541                 Rvalue::Cast(
 542                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 543                     ref operand,
 544                     to_ty,
 545                 ) => {
 546                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 547                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 548                     match *from_ty.kind() {
 549                         ty::FnDef(def_id, substs) => {
 550                             let func_ref = fx.get_function_ref(
 551                                 Instance::resolve_for_fn_ptr(
 552                                     fx.tcx,
 553                                     ParamEnv::reveal_all(),
 554                                     def_id,
 555                                     substs,
 556                                 )
 557                                 .unwrap()
 558                                 .polymorphize(fx.tcx),
 559                             );
 560                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 561                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 562                         }
 563                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 564                     }
 565                 }
 566                 Rvalue::Cast(
 567                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 568                     ref operand,
 569                     to_ty,
 570                 )
 571                 | Rvalue::Cast(
 572                     CastKind::Pointer(PointerCast::MutToConstPointer),
 573                     ref operand,
 574                     to_ty,
 575                 )
 576                 | Rvalue::Cast(
 577                     CastKind::Pointer(PointerCast::ArrayToPointer),
 578                     ref operand,
 579                     to_ty,
 580                 ) => {
 581                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 582                     let operand = codegen_operand(fx, operand);
 583                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 584                 }
 585                 Rvalue::Cast(CastKind::Misc, ref operand, to_ty) => {
 586                     let operand = codegen_operand(fx, operand);
 587                     let from_ty = operand.layout().ty;
 588                     let to_ty = fx.monomorphize(to_ty);
 589
 590                     fn is_fat_ptr<'tcx>(
 591                         fx: &FunctionCx<'_, 'tcx, impl Module>,
 592                         ty: Ty<'tcx>,
 593                     ) -> bool {
 594                         ty.builtin_deref(true)
 595                             .map(
 596                                 |ty::TypeAndMut {
 597                                      ty: pointee_ty,
 598                                      mutbl: _,
 599                                  }| {
 600                                     has_ptr_meta(fx.tcx, pointee_ty)
 601                                 },
 602                             )
 603                             .unwrap_or(false)
 604                     }
 605
 606                     if is_fat_ptr(fx, from_ty) {
 607                         if is_fat_ptr(fx, to_ty) {
 608                             // fat-ptr -> fat-ptr
 609                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 610                         } else {
 611                             // fat-ptr -> thin-ptr
 612                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 613                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 614                         }
 615                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 616                         // enum -> discriminant value
 617                         assert!(adt_def.is_enum());
 618                         match to_ty.kind() {
 619                             ty::Uint(_) | ty::Int(_) => {}
 620                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 621                         }
 622
 623                         use rustc_target::abi::{Int, TagEncoding, Variants};
 624
 625                         match operand.layout().variants {
 626                             Variants::Single { index } => {
 627                                 let discr = operand
 628                                     .layout()
 629                                     .ty
 630                                     .discriminant_for_variant(fx.tcx, index)
 631                                     .unwrap();
 632                                 let discr = if discr.ty.is_signed() {
 633                                     fx.layout_of(discr.ty).size.sign_extend(discr.val)
 634                                 } else {
 635                                     discr.val
 636                                 };
 637                                 let discr = discr.into();
 638
 639                                 let discr = CValue::const_val(fx, fx.layout_of(to_ty), discr);
 640                                 lval.write_cvalue(fx, discr);
 641                             }
 642                             Variants::Multiple {
 643                                 ref tag,
 644                                 tag_field,
 645                                 tag_encoding: TagEncoding::Direct,
 646                                 variants: _,
 647                             } => {
 648                                 let cast_to = fx.clif_type(dest_layout.ty).unwrap();
 649
 650                                 // Read the tag/niche-encoded discriminant from memory.
 651                                 let encoded_discr =
 652                                     operand.value_field(fx, mir::Field::new(tag_field));
 653                                 let encoded_discr = encoded_discr.load_scalar(fx);
 654
 655                                 // Decode the discriminant (specifically if it's niche-encoded).
 656                                 let signed = match tag.value {
 657                                     Int(_, signed) => signed,
 658                                     _ => false,
 659                                 };
 660                                 let val = clif_intcast(fx, encoded_discr, cast_to, signed);
 661                                 let val = CValue::by_val(val, dest_layout);
 662                                 lval.write_cvalue(fx, val);
 663                             }
 664                             Variants::Multiple { .. } => unreachable!(),
 665                         }
 666                     } else {
 667                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 668                         let from = operand.load_scalar(fx);
 669
 670                         let res = clif_int_or_float_cast(
 671                             fx,
 672                             from,
 673                             type_sign(from_ty),
 674                             to_clif_ty,
 675                             type_sign(to_ty),
 676                         );
 677                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 678                     }
 679                 }
 680                 Rvalue::Cast(
 681                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 682                     ref operand,
 683                     _to_ty,
 684                 ) => {
 685                     let operand = codegen_operand(fx, operand);
 686                     match *operand.layout().ty.kind() {
 687                         ty::Closure(def_id, substs) => {
 688                             let instance = Instance::resolve_closure(
 689                                 fx.tcx,
 690                                 def_id,
 691                                 substs,
 692                                 ty::ClosureKind::FnOnce,
 693                             )
 694                             .polymorphize(fx.tcx);
 695                             let func_ref = fx.get_function_ref(instance);
 696                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 697                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 698                         }
 699                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 700                     }
 701                 }
 702                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 703                     let operand = codegen_operand(fx, operand);
 704                     operand.unsize_value(fx, lval);
 705                 }
 706                 Rvalue::Discriminant(place) => {
 707                     let place = codegen_place(fx, place);
 708                     let value = place.to_cvalue(fx);
 709                     let discr =
 710                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 711                     lval.write_cvalue(fx, discr);
 712                 }
 713                 Rvalue::Repeat(ref operand, times) => {
 714                     let operand = codegen_operand(fx, operand);
 715                     let times = fx
 716                         .monomorphize(times)
 717                         .eval(fx.tcx, ParamEnv::reveal_all())
 718                         .val
 719                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 720                         .unwrap();
 721                     if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 722                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 723                         // FIXME use emit_small_memset where possible
 724                         let addr = lval.to_ptr().get_addr(fx);
 725                         let val = operand.load_scalar(fx);
 726                         fx.bcx
 727                             .call_memset(fx.cx.module.target_config(), addr, val, times);
 728                     } else {
 729                         let loop_block = fx.bcx.create_block();
 730                         let loop_block2 = fx.bcx.create_block();
 731                         let done_block = fx.bcx.create_block();
 732                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 733                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 734                         fx.bcx.ins().jump(loop_block, &[zero]);
 735
 736                         fx.bcx.switch_to_block(loop_block);
 737                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 738                         fx.bcx.ins().brnz(done, done_block, &[]);
 739                         fx.bcx.ins().jump(loop_block2, &[]);
 740
 741                         fx.bcx.switch_to_block(loop_block2);
 742                         let to = lval.place_index(fx, index);
 743                         to.write_cvalue(fx, operand);
 744                         let index = fx.bcx.ins().iadd_imm(index, 1);
 745                         fx.bcx.ins().jump(loop_block, &[index]);
 746
 747                         fx.bcx.switch_to_block(done_block);
 748                         fx.bcx.ins().nop();
 749                     }
 750                 }
 751                 Rvalue::Len(place) => {
 752                     let place = codegen_place(fx, place);
 753                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 754                     let len = codegen_array_len(fx, place);
 755                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 756                 }
 757                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 758                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 759                     let content_ty = fx.monomorphize(content_ty);
 760                     let layout = fx.layout_of(content_ty);
 761                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 762                     let llalign = fx
 763                         .bcx
 764                         .ins()
 765                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 766                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 767
 768                     // Allocate space:
 769                     let def_id = match fx
 770                         .tcx
 771                         .lang_items()
 772                         .require(rustc_hir::LangItem::ExchangeMalloc)
 773                     {
 774                         Ok(id) => id,
 775                         Err(s) => {
 776                             fx.tcx
 777                                 .sess
 778                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 779                         }
 780                     };
 781                     let instance = ty::Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 782                     let func_ref = fx.get_function_ref(instance);
 783                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 784                     let ptr = fx.bcx.inst_results(call)[0];
 785                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 786                 }
 787                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 788                     assert!(lval
 789                         .layout()
 790                         .ty
 791                         .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all()));
 792                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 793                     let val =
 794                         CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 795                     lval.write_cvalue(fx, val);
 796                 }
 797                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 798                     AggregateKind::Array(_ty) => {
 799                         for (i, operand) in operands.iter().enumerate() {
 800                             let operand = codegen_operand(fx, operand);
 801                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 802                             let to = lval.place_index(fx, index);
 803                             to.write_cvalue(fx, operand);
 804                         }
 805                     }
 806                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 807                 },
 808             }
 809         }
 810         StatementKind::StorageLive(_)
 811         | StatementKind::StorageDead(_)
 812         | StatementKind::Nop
 813         | StatementKind::FakeRead(..)
 814         | StatementKind::Retag { .. }
 815         | StatementKind::AscribeUserType(..) => {}
 816
 817         StatementKind::LlvmInlineAsm(asm) => {
 818             use rustc_span::symbol::Symbol;
 819             let LlvmInlineAsm {
 820                 asm,
 821                 outputs,
 822                 inputs,
 823             } = &**asm;
 824             let rustc_hir::LlvmInlineAsmInner {
 825                 asm: asm_code,         // Name
 826                 outputs: output_names, // Vec<LlvmInlineAsmOutput>
 827                 inputs: input_names,   // Vec<Name>
 828                 clobbers,              // Vec<Name>
 829                 volatile,              // bool
 830                 alignstack,            // bool
 831                 dialect: _,
 832                 asm_str_style: _,
 833             } = asm;
 834             match asm_code.as_str().trim() {
 835                 "" => {
 836                     // Black box
 837                 }
 838                 "mov %rbx, %rsi\n                  cpuid\n                  xchg %rbx, %rsi" => {
 839                     assert_eq!(
 840                         input_names,
 841                         &[Symbol::intern("{eax}"), Symbol::intern("{ecx}")]
 842                     );
 843                     assert_eq!(output_names.len(), 4);
 844                     for (i, c) in (&["={eax}", "={esi}", "={ecx}", "={edx}"])
 845                         .iter()
 846                         .enumerate()
 847                     {
 848                         assert_eq!(&output_names[i].constraint.as_str(), c);
 849                         assert!(!output_names[i].is_rw);
 850                         assert!(!output_names[i].is_indirect);
 851                     }
 852
 853                     assert_eq!(clobbers, &[]);
 854
 855                     assert!(!volatile);
 856                     assert!(!alignstack);
 857
 858                     assert_eq!(inputs.len(), 2);
 859                     let leaf = codegen_operand(fx, &inputs[0].1).load_scalar(fx); // %eax
 860                     let subleaf = codegen_operand(fx, &inputs[1].1).load_scalar(fx); // %ecx
 861
 862                     let (eax, ebx, ecx, edx) =
 863                         crate::intrinsics::codegen_cpuid_call(fx, leaf, subleaf);
 864
 865                     assert_eq!(outputs.len(), 4);
 866                     codegen_place(fx, outputs[0])
 867                         .write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
 868                     codegen_place(fx, outputs[1])
 869                         .write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
 870                     codegen_place(fx, outputs[2])
 871                         .write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
 872                     codegen_place(fx, outputs[3])
 873                         .write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
 874                 }
 875                 "xgetbv" => {
 876                     assert_eq!(input_names, &[Symbol::intern("{ecx}")]);
 877
 878                     assert_eq!(output_names.len(), 2);
 879                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 880                         assert_eq!(&output_names[i].constraint.as_str(), c);
 881                         assert!(!output_names[i].is_rw);
 882                         assert!(!output_names[i].is_indirect);
 883                     }
 884
 885                     assert_eq!(clobbers, &[]);
 886
 887                     assert!(!volatile);
 888                     assert!(!alignstack);
 889
 890                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 891                 }
 892                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 893                 _ if fx
 894                     .tcx
 895                     .symbol_name(fx.instance)
 896                     .name
 897                     .starts_with("___chkstk") =>
 898                 {
 899                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 900                 }
 901                 _ if fx.tcx.symbol_name(fx.instance).name == "__alloca" => {
 902                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 903                 }
 904                 // Used in sys::windows::abort_internal
 905                 "int $$0x29" => {
 906                     crate::trap::trap_unimplemented(fx, "Windows abort");
 907                 }
 908                 _ => fx
 909                     .tcx
 910                     .sess
 911                     .span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 912             }
 913         }
 914         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 915     }
 916 }
 917
 918 fn codegen_array_len<'tcx>(
 919     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 920     place: CPlace<'tcx>,
 921 ) -> Value {
 922     match *place.layout().ty.kind() {
 923         ty::Array(_elem_ty, len) => {
 924             let len = fx
 925                 .monomorphize(len)
 926                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 927             fx.bcx.ins().iconst(fx.pointer_type, len)
 928         }
 929         ty::Slice(_elem_ty) => place
 930             .to_ptr_maybe_unsized()
 931             .1
 932             .expect("Length metadata for slice place"),
 933         _ => bug!("Rvalue::Len({:?})", place),
 934     }
 935 }
 936
 937 pub(crate) fn codegen_place<'tcx>(
 938     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
 939     place: Place<'tcx>,
 940 ) -> CPlace<'tcx> {
 941     let mut cplace = fx.get_local_place(place.local);
 942
 943     for elem in place.projection {
 944         match elem {
 945             PlaceElem::Deref => {
 946                 cplace = cplace.place_deref(fx);
 947             }
 948             PlaceElem::Field(field, _ty) => {
 949                 cplace = cplace.place_field(fx, field);
 950             }
 951             PlaceElem::Index(local) => {
 952                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 953                 cplace = cplace.place_index(fx, index);
 954             }
 955             PlaceElem::ConstantIndex {
 956                 offset,
 957                 min_length: _,
 958                 from_end,
 959             } => {
 960                 let offset: u64 = offset;
 961                 let index = if !from_end {
 962                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 963                 } else {
 964                     let len = codegen_array_len(fx, cplace);
 965                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 966                 };
 967                 cplace = cplace.place_index(fx, index);
 968             }
 969             PlaceElem::Subslice { from, to, from_end } => {
 970                 // These indices are generated by slice patterns.
 971                 // slice[from:-to] in Python terms.
 972
 973                 let from: u64 = from;
 974                 let to: u64 = to;
 975
 976                 match cplace.layout().ty.kind() {
 977                     ty::Array(elem_ty, _len) => {
 978                         assert!(!from_end, "array subslices are never `from_end`");
 979                         let elem_layout = fx.layout_of(elem_ty);
 980                         let ptr = cplace.to_ptr();
 981                         cplace = CPlace::for_ptr(
 982                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 983                             fx.layout_of(fx.tcx.mk_array(elem_ty, to - from)),
 984                         );
 985                     }
 986                     ty::Slice(elem_ty) => {
 987                         assert!(from_end, "slice subslices should be `from_end`");
 988                         let elem_layout = fx.layout_of(elem_ty);
 989                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 990                         let len = len.unwrap();
 991                         cplace = CPlace::for_ptr_with_extra(
 992                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 993                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 994                             cplace.layout(),
 995                         );
 996                     }
 997                     _ => unreachable!(),
 998                 }
 999             }
1000             PlaceElem::Downcast(_adt_def, variant) => {
1001                 cplace = cplace.downcast_variant(fx, variant);
1002             }
1003         }
1004     }
1005
1006     cplace
1007 }
1008
1009 pub(crate) fn codegen_operand<'tcx>(
1010     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
1011     operand: &Operand<'tcx>,
1012 ) -> CValue<'tcx> {
1013     match operand {
1014         Operand::Move(place) | Operand::Copy(place) => {
1015             let cplace = codegen_place(fx, *place);
1016             cplace.to_cvalue(fx)
1017         }
1018         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
1019     }
1020 }
1021
1022 pub(crate) fn codegen_panic<'tcx>(
1023     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
1024     msg_str: &str,
1025     span: Span,
1026 ) {
1027     let location = fx.get_caller_location(span).load_scalar(fx);
1028
1029     let msg_ptr = fx.anonymous_str("assert", msg_str);
1030     let msg_len = fx
1031         .bcx
1032         .ins()
1033         .iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
1034     let args = [msg_ptr, msg_len, location];
1035
1036     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, span);
1037 }
1038
1039 pub(crate) fn codegen_panic_inner<'tcx>(
1040     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
1041     lang_item: rustc_hir::LangItem,
1042     args: &[Value],
1043     span: Span,
1044 ) {
1045     let def_id = fx
1046         .tcx
1047         .lang_items()
1048         .require(lang_item)
1049         .unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
1050
1051     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
1052     let symbol_name = fx.tcx.symbol_name(instance).name;
1053
1054     fx.lib_call(
1055         &*symbol_name,
1056         vec![fx.pointer_type, fx.pointer_type, fx.pointer_type],
1057         vec![],
1058         args,
1059     );
1060
1061     crate::trap::trap_unreachable(fx, "panic lang item returned");
1062 }