src/base.rs

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