compiler/rustc_codegen_cranelift/src/base.rs

   1 //! Codegen of a single function
   2
   3 use rustc_ast::InlineAsmOptions;
   4 use rustc_index::vec::IndexVec;
   5 use rustc_middle::ty::adjustment::PointerCast;
   6 use rustc_middle::ty::layout::FnAbiOf;
   7 use rustc_middle::ty::print::with_no_trimmed_paths;
   8
   9 use indexmap::IndexSet;
  10
  11 use crate::constant::ConstantCx;
  12 use crate::prelude::*;
  13 use crate::pretty_clif::CommentWriter;
  14
  15 pub(crate) fn codegen_fn<'tcx>(
  16     cx: &mut crate::CodegenCx<'tcx>,
  17     module: &mut dyn Module,
  18     instance: Instance<'tcx>,
  19 ) {
  20     let tcx = cx.tcx;
  21
  22     let _inst_guard =
  23         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  24     debug_assert!(!instance.substs.needs_infer());
  25
  26     let mir = tcx.instance_mir(instance.def);
  27     let _mir_guard = crate::PrintOnPanic(|| {
  28         let mut buf = Vec::new();
  29         with_no_trimmed_paths!({
  30             rustc_middle::mir::pretty::write_mir_fn(tcx, mir, &mut |_, _| Ok(()), &mut buf)
  31                 .unwrap();
  32         });
  33         String::from_utf8_lossy(&buf).into_owned()
  34     });
  35
  36     // Declare function
  37     let symbol_name = tcx.symbol_name(instance);
  38     let sig = get_function_sig(tcx, module.isa().triple(), instance);
  39     let func_id = module.declare_function(symbol_name.name, Linkage::Local, &sig).unwrap();
  40
  41     cx.cached_context.clear();
  42
  43     // Make the FunctionBuilder
  44     let mut func_ctx = FunctionBuilderContext::new();
  45     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  46     func.name = ExternalName::user(0, func_id.as_u32());
  47     func.signature = sig;
  48     func.collect_debug_info();
  49
  50     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  51
  52     // Predefine blocks
  53     let start_block = bcx.create_block();
  54     let block_map: IndexVec<BasicBlock, Block> =
  55         (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  56
  57     // Make FunctionCx
  58     let target_config = module.target_config();
  59     let pointer_type = target_config.pointer_type();
  60     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  61
  62     let mut fx = FunctionCx {
  63         cx,
  64         module,
  65         tcx,
  66         target_config,
  67         pointer_type,
  68         constants_cx: ConstantCx::new(),
  69
  70         instance,
  71         symbol_name,
  72         mir,
  73         fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())),
  74
  75         bcx,
  76         block_map,
  77         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  78         caller_location: None, // set by `codegen_fn_prelude`
  79
  80         clif_comments,
  81         source_info_set: indexmap::IndexSet::new(),
  82         next_ssa_var: 0,
  83     };
  84
  85     let arg_uninhabited = fx
  86         .mir
  87         .args_iter()
  88         .any(|arg| fx.layout_of(fx.monomorphize(fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  89
  90     if !crate::constant::check_constants(&mut fx) {
  91         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  92         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  93         crate::trap::trap_unreachable(&mut fx, "compilation should have been aborted");
  94     } else if arg_uninhabited {
  95         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  96         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  97         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
  98     } else {
  99         tcx.sess.time("codegen clif ir", || {
 100             tcx.sess
 101                 .time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
 102             codegen_fn_content(&mut fx);
 103         });
 104     }
 105
 106     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 107     let instance = fx.instance;
 108     let clif_comments = fx.clif_comments;
 109     let source_info_set = fx.source_info_set;
 110     let local_map = fx.local_map;
 111
 112     fx.constants_cx.finalize(fx.tcx, &mut *fx.module);
 113
 114     crate::pretty_clif::write_clif_file(
 115         tcx,
 116         "unopt",
 117         module.isa(),
 118         instance,
 119         &func,
 120         &clif_comments,
 121     );
 122
 123     // Verify function
 124     verify_func(tcx, &clif_comments, &func);
 125
 126     compile_fn(
 127         cx,
 128         module,
 129         instance,
 130         symbol_name.name,
 131         func_id,
 132         func,
 133         clif_comments,
 134         source_info_set,
 135         local_map,
 136     );
 137 }
 138
 139 fn compile_fn<'tcx>(
 140     cx: &mut crate::CodegenCx<'tcx>,
 141     module: &mut dyn Module,
 142     instance: Instance<'tcx>,
 143     symbol_name: &str,
 144     func_id: FuncId,
 145     func: Function,
 146     mut clif_comments: CommentWriter,
 147     source_info_set: IndexSet<SourceInfo>,
 148     local_map: IndexVec<mir::Local, CPlace<'tcx>>,
 149 ) {
 150     let tcx = cx.tcx;
 151
 152     // Store function in context
 153     let context = &mut cx.cached_context;
 154     context.clear();
 155     context.func = func;
 156
 157     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 158     // instruction, which doesn't have an encoding.
 159     context.compute_cfg();
 160     context.compute_domtree();
 161     context.eliminate_unreachable_code(module.isa()).unwrap();
 162     context.dce(module.isa()).unwrap();
 163     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 164     // invalidate it when it would change.
 165     context.domtree.clear();
 166
 167     // Perform rust specific optimizations
 168     tcx.sess.time("optimize clif ir", || {
 169         crate::optimize::optimize_function(
 170             tcx,
 171             module.isa(),
 172             instance,
 173             context,
 174             &mut clif_comments,
 175         );
 176     });
 177
 178     // Define function
 179     tcx.sess.time("define function", || {
 180         context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 181         module.define_function(func_id, context).unwrap()
 182     });
 183
 184     // Write optimized function to file for debugging
 185     crate::pretty_clif::write_clif_file(
 186         tcx,
 187         "opt",
 188         module.isa(),
 189         instance,
 190         &context.func,
 191         &clif_comments,
 192     );
 193
 194     if let Some(disasm) = &context.mach_compile_result.as_ref().unwrap().disasm {
 195         crate::pretty_clif::write_ir_file(
 196             tcx,
 197             || format!("{}.vcode", tcx.symbol_name(instance).name),
 198             |file| file.write_all(disasm.as_bytes()),
 199         )
 200     }
 201
 202     // Define debuginfo for function
 203     let isa = module.isa();
 204     let debug_context = &mut cx.debug_context;
 205     let unwind_context = &mut cx.unwind_context;
 206     tcx.sess.time("generate debug info", || {
 207         if let Some(debug_context) = debug_context {
 208             debug_context.define_function(
 209                 instance,
 210                 func_id,
 211                 symbol_name,
 212                 isa,
 213                 context,
 214                 &source_info_set,
 215                 local_map,
 216             );
 217         }
 218         unwind_context.add_function(func_id, &context, isa);
 219     });
 220 }
 221
 222 pub(crate) fn verify_func(
 223     tcx: TyCtxt<'_>,
 224     writer: &crate::pretty_clif::CommentWriter,
 225     func: &Function,
 226 ) {
 227     tcx.sess.time("verify clif ir", || {
 228         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 229         match cranelift_codegen::verify_function(&func, &flags) {
 230             Ok(_) => {}
 231             Err(err) => {
 232                 tcx.sess.err(&format!("{:?}", err));
 233                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 234                     &func,
 235                     Some(Box::new(writer)),
 236                     err,
 237                 );
 238                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 239             }
 240         }
 241     });
 242 }
 243
 244 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, '_>) {
 245     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 246         let block = fx.get_block(bb);
 247         fx.bcx.switch_to_block(block);
 248
 249         if bb_data.is_cleanup {
 250             // Unwinding after panicking is not supported
 251             continue;
 252
 253             // FIXME Once unwinding is supported and Cranelift supports marking blocks as cold, do
 254             // so for cleanup blocks.
 255         }
 256
 257         fx.bcx.ins().nop();
 258         for stmt in &bb_data.statements {
 259             fx.set_debug_loc(stmt.source_info);
 260             codegen_stmt(fx, block, stmt);
 261         }
 262
 263         if fx.clif_comments.enabled() {
 264             let mut terminator_head = "\n".to_string();
 265             with_no_trimmed_paths!({
 266                 bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 267             });
 268             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 269             fx.add_comment(inst, terminator_head);
 270         }
 271
 272         let source_info = bb_data.terminator().source_info;
 273         fx.set_debug_loc(source_info);
 274
 275         match &bb_data.terminator().kind {
 276             TerminatorKind::Goto { target } => {
 277                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 278                     let mut can_immediately_return = true;
 279                     for stmt in &fx.mir[*target].statements {
 280                         if let StatementKind::StorageDead(_) = stmt.kind {
 281                         } else {
 282                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 283                             can_immediately_return = false;
 284                             break;
 285                         }
 286                     }
 287
 288                     if can_immediately_return {
 289                         crate::abi::codegen_return(fx);
 290                         continue;
 291                     }
 292                 }
 293
 294                 let block = fx.get_block(*target);
 295                 fx.bcx.ins().jump(block, &[]);
 296             }
 297             TerminatorKind::Return => {
 298                 crate::abi::codegen_return(fx);
 299             }
 300             TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
 301                 if !fx.tcx.sess.overflow_checks() {
 302                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 303                         let target = fx.get_block(*target);
 304                         fx.bcx.ins().jump(target, &[]);
 305                         continue;
 306                     }
 307                 }
 308                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 309
 310                 let target = fx.get_block(*target);
 311                 let failure = fx.bcx.create_block();
 312                 fx.bcx.set_cold_block(failure);
 313
 314                 if *expected {
 315                     fx.bcx.ins().brz(cond, failure, &[]);
 316                 } else {
 317                     fx.bcx.ins().brnz(cond, failure, &[]);
 318                 };
 319                 fx.bcx.ins().jump(target, &[]);
 320
 321                 fx.bcx.switch_to_block(failure);
 322                 fx.bcx.ins().nop();
 323
 324                 match msg {
 325                     AssertKind::BoundsCheck { ref len, ref index } => {
 326                         let len = codegen_operand(fx, len).load_scalar(fx);
 327                         let index = codegen_operand(fx, index).load_scalar(fx);
 328                         let location = fx.get_caller_location(source_info).load_scalar(fx);
 329
 330                         codegen_panic_inner(
 331                             fx,
 332                             rustc_hir::LangItem::PanicBoundsCheck,
 333                             &[index, len, location],
 334                             source_info.span,
 335                         );
 336                     }
 337                     _ => {
 338                         let msg_str = msg.description();
 339                         codegen_panic(fx, msg_str, source_info);
 340                     }
 341                 }
 342             }
 343
 344             TerminatorKind::SwitchInt { discr, switch_ty, targets } => {
 345                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 346
 347                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 348                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 349                 if use_bool_opt {
 350                     assert_eq!(targets.iter().count(), 1);
 351                     let (then_value, then_block) = targets.iter().next().unwrap();
 352                     let then_block = fx.get_block(then_block);
 353                     let else_block = fx.get_block(targets.otherwise());
 354                     let test_zero = match then_value {
 355                         0 => true,
 356                         1 => false,
 357                         _ => unreachable!("{:?}", targets),
 358                     };
 359
 360                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 361                     let (discr, is_inverted) =
 362                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 363                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 364                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 365                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 366                         &fx.bcx, discr, test_zero,
 367                     ) {
 368                         if taken {
 369                             fx.bcx.ins().jump(then_block, &[]);
 370                         } else {
 371                             fx.bcx.ins().jump(else_block, &[]);
 372                         }
 373                     } else {
 374                         if test_zero {
 375                             fx.bcx.ins().brz(discr, then_block, &[]);
 376                             fx.bcx.ins().jump(else_block, &[]);
 377                         } else {
 378                             fx.bcx.ins().brnz(discr, then_block, &[]);
 379                             fx.bcx.ins().jump(else_block, &[]);
 380                         }
 381                     }
 382                 } else {
 383                     let mut switch = ::cranelift_frontend::Switch::new();
 384                     for (value, block) in targets.iter() {
 385                         let block = fx.get_block(block);
 386                         switch.set_entry(value, block);
 387                     }
 388                     let otherwise_block = fx.get_block(targets.otherwise());
 389                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 390                 }
 391             }
 392             TerminatorKind::Call {
 393                 func,
 394                 args,
 395                 destination,
 396                 target,
 397                 fn_span,
 398                 cleanup: _,
 399                 from_hir_call: _,
 400             } => {
 401                 fx.tcx.sess.time("codegen call", || {
 402                     crate::abi::codegen_terminator_call(
 403                         fx,
 404                         mir::SourceInfo { span: *fn_span, ..source_info },
 405                         func,
 406                         args,
 407                         *destination,
 408                         *target,
 409                     )
 410                 });
 411             }
 412             TerminatorKind::InlineAsm {
 413                 template,
 414                 operands,
 415                 options,
 416                 destination,
 417                 line_spans: _,
 418                 cleanup: _,
 419             } => {
 420                 if options.contains(InlineAsmOptions::MAY_UNWIND) {
 421                     fx.tcx.sess.span_fatal(
 422                         source_info.span,
 423                         "cranelift doesn't support unwinding from inline assembly.",
 424                     );
 425                 }
 426
 427                 crate::inline_asm::codegen_inline_asm(
 428                     fx,
 429                     source_info.span,
 430                     template,
 431                     operands,
 432                     *options,
 433                 );
 434
 435                 match *destination {
 436                     Some(destination) => {
 437                         let destination_block = fx.get_block(destination);
 438                         fx.bcx.ins().jump(destination_block, &[]);
 439                     }
 440                     None => {
 441                         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 442                     }
 443                 }
 444             }
 445             TerminatorKind::Resume | TerminatorKind::Abort => {
 446                 // FIXME implement unwinding
 447                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 448             }
 449             TerminatorKind::Unreachable => {
 450                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 451             }
 452             TerminatorKind::Yield { .. }
 453             | TerminatorKind::FalseEdge { .. }
 454             | TerminatorKind::FalseUnwind { .. }
 455             | TerminatorKind::DropAndReplace { .. }
 456             | TerminatorKind::GeneratorDrop => {
 457                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 458             }
 459             TerminatorKind::Drop { place, target, unwind: _ } => {
 460                 let drop_place = codegen_place(fx, *place);
 461                 crate::abi::codegen_drop(fx, source_info, drop_place);
 462
 463                 let target_block = fx.get_block(*target);
 464                 fx.bcx.ins().jump(target_block, &[]);
 465             }
 466         };
 467     }
 468
 469     fx.bcx.seal_all_blocks();
 470     fx.bcx.finalize();
 471 }
 472
 473 fn codegen_stmt<'tcx>(
 474     fx: &mut FunctionCx<'_, '_, 'tcx>,
 475     #[allow(unused_variables)] cur_block: Block,
 476     stmt: &Statement<'tcx>,
 477 ) {
 478     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 479
 480     fx.set_debug_loc(stmt.source_info);
 481
 482     #[cfg(any())] // This is never true
 483     match &stmt.kind {
 484         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 485         _ => {
 486             if fx.clif_comments.enabled() {
 487                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 488                 fx.add_comment(inst, format!("{:?}", stmt));
 489             }
 490         }
 491     }
 492
 493     match &stmt.kind {
 494         StatementKind::SetDiscriminant { place, variant_index } => {
 495             let place = codegen_place(fx, **place);
 496             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 497         }
 498         StatementKind::Assign(to_place_and_rval) => {
 499             let lval = codegen_place(fx, to_place_and_rval.0);
 500             let dest_layout = lval.layout();
 501             match to_place_and_rval.1 {
 502                 Rvalue::Use(ref operand) => {
 503                     let val = codegen_operand(fx, operand);
 504                     lval.write_cvalue(fx, val);
 505                 }
 506                 Rvalue::CopyForDeref(place) => {
 507                     let cplace = codegen_place(fx, place);
 508                     let val = cplace.to_cvalue(fx);
 509                     lval.write_cvalue(fx, val)
 510                 }
 511                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 512                     let place = codegen_place(fx, place);
 513                     let ref_ = place.place_ref(fx, lval.layout());
 514                     lval.write_cvalue(fx, ref_);
 515                 }
 516                 Rvalue::ThreadLocalRef(def_id) => {
 517                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 518                     lval.write_cvalue(fx, val);
 519                 }
 520                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 521                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 522                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 523
 524                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 525                     lval.write_cvalue(fx, res);
 526                 }
 527                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 528                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 529                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 530
 531                     let res = if !fx.tcx.sess.overflow_checks() {
 532                         let val =
 533                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 534                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 535                         CValue::by_val_pair(val, is_overflow, lval.layout())
 536                     } else {
 537                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 538                     };
 539
 540                     lval.write_cvalue(fx, res);
 541                 }
 542                 Rvalue::UnaryOp(un_op, ref operand) => {
 543                     let operand = codegen_operand(fx, operand);
 544                     let layout = operand.layout();
 545                     let val = operand.load_scalar(fx);
 546                     let res = match un_op {
 547                         UnOp::Not => match layout.ty.kind() {
 548                             ty::Bool => {
 549                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 550                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 551                             }
 552                             ty::Uint(_) | ty::Int(_) => {
 553                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 554                             }
 555                             _ => unreachable!("un op Not for {:?}", layout.ty),
 556                         },
 557                         UnOp::Neg => match layout.ty.kind() {
 558                             ty::Int(IntTy::I128) => {
 559                                 // FIXME remove this case once ineg.i128 works
 560                                 let zero =
 561                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 562                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 563                             }
 564                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 565                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 566                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 567                         },
 568                     };
 569                     lval.write_cvalue(fx, res);
 570                 }
 571                 Rvalue::Cast(
 572                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 573                     ref operand,
 574                     to_ty,
 575                 ) => {
 576                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 577                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 578                     match *from_ty.kind() {
 579                         ty::FnDef(def_id, substs) => {
 580                             let func_ref = fx.get_function_ref(
 581                                 Instance::resolve_for_fn_ptr(
 582                                     fx.tcx,
 583                                     ParamEnv::reveal_all(),
 584                                     def_id,
 585                                     substs,
 586                                 )
 587                                 .unwrap()
 588                                 .polymorphize(fx.tcx),
 589                             );
 590                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 591                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 592                         }
 593                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 594                     }
 595                 }
 596                 Rvalue::Cast(
 597                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 598                     ref operand,
 599                     to_ty,
 600                 )
 601                 | Rvalue::Cast(
 602                     CastKind::Pointer(PointerCast::MutToConstPointer),
 603                     ref operand,
 604                     to_ty,
 605                 )
 606                 | Rvalue::Cast(
 607                     CastKind::Pointer(PointerCast::ArrayToPointer),
 608                     ref operand,
 609                     to_ty,
 610                 ) => {
 611                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 612                     let operand = codegen_operand(fx, operand);
 613                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 614                 }
 615                 Rvalue::Cast(
 616                     CastKind::Misc
 617                     | CastKind::PointerExposeAddress
 618                     | CastKind::PointerFromExposedAddress,
 619                     ref operand,
 620                     to_ty,
 621                 ) => {
 622                     let operand = codegen_operand(fx, operand);
 623                     let from_ty = operand.layout().ty;
 624                     let to_ty = fx.monomorphize(to_ty);
 625
 626                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 627                         ty.builtin_deref(true)
 628                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 629                                 has_ptr_meta(fx.tcx, pointee_ty)
 630                             })
 631                             .unwrap_or(false)
 632                     }
 633
 634                     if is_fat_ptr(fx, from_ty) {
 635                         if is_fat_ptr(fx, to_ty) {
 636                             // fat-ptr -> fat-ptr
 637                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 638                         } else {
 639                             // fat-ptr -> thin-ptr
 640                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 641                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 642                         }
 643                     } else {
 644                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 645                         let from = operand.load_scalar(fx);
 646
 647                         let res = clif_int_or_float_cast(
 648                             fx,
 649                             from,
 650                             type_sign(from_ty),
 651                             to_clif_ty,
 652                             type_sign(to_ty),
 653                         );
 654                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 655                     }
 656                 }
 657                 Rvalue::Cast(
 658                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 659                     ref operand,
 660                     _to_ty,
 661                 ) => {
 662                     let operand = codegen_operand(fx, operand);
 663                     match *operand.layout().ty.kind() {
 664                         ty::Closure(def_id, substs) => {
 665                             let instance = Instance::resolve_closure(
 666                                 fx.tcx,
 667                                 def_id,
 668                                 substs,
 669                                 ty::ClosureKind::FnOnce,
 670                             )
 671                             .expect("failed to normalize and resolve closure during codegen")
 672                             .polymorphize(fx.tcx);
 673                             let func_ref = fx.get_function_ref(instance);
 674                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 675                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 676                         }
 677                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 678                     }
 679                 }
 680                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 681                     let operand = codegen_operand(fx, operand);
 682                     operand.unsize_value(fx, lval);
 683                 }
 684                 Rvalue::Discriminant(place) => {
 685                     let place = codegen_place(fx, place);
 686                     let value = place.to_cvalue(fx);
 687                     let discr =
 688                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 689                     lval.write_cvalue(fx, discr);
 690                 }
 691                 Rvalue::Repeat(ref operand, times) => {
 692                     let operand = codegen_operand(fx, operand);
 693                     let times = fx
 694                         .monomorphize(times)
 695                         .eval(fx.tcx, ParamEnv::reveal_all())
 696                         .kind()
 697                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 698                         .unwrap();
 699                     if operand.layout().size.bytes() == 0 {
 700                         // Do nothing for ZST's
 701                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 702                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 703                         // FIXME use emit_small_memset where possible
 704                         let addr = lval.to_ptr().get_addr(fx);
 705                         let val = operand.load_scalar(fx);
 706                         fx.bcx.call_memset(fx.target_config, addr, val, times);
 707                     } else {
 708                         let loop_block = fx.bcx.create_block();
 709                         let loop_block2 = fx.bcx.create_block();
 710                         let done_block = fx.bcx.create_block();
 711                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 712                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 713                         fx.bcx.ins().jump(loop_block, &[zero]);
 714
 715                         fx.bcx.switch_to_block(loop_block);
 716                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 717                         fx.bcx.ins().brnz(done, done_block, &[]);
 718                         fx.bcx.ins().jump(loop_block2, &[]);
 719
 720                         fx.bcx.switch_to_block(loop_block2);
 721                         let to = lval.place_index(fx, index);
 722                         to.write_cvalue(fx, operand);
 723                         let index = fx.bcx.ins().iadd_imm(index, 1);
 724                         fx.bcx.ins().jump(loop_block, &[index]);
 725
 726                         fx.bcx.switch_to_block(done_block);
 727                         fx.bcx.ins().nop();
 728                     }
 729                 }
 730                 Rvalue::Len(place) => {
 731                     let place = codegen_place(fx, place);
 732                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 733                     let len = codegen_array_len(fx, place);
 734                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 735                 }
 736                 Rvalue::ShallowInitBox(ref operand, content_ty) => {
 737                     let content_ty = fx.monomorphize(content_ty);
 738                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 739                     let operand = codegen_operand(fx, operand);
 740                     let operand = operand.load_scalar(fx);
 741                     lval.write_cvalue(fx, CValue::by_val(operand, box_layout));
 742                 }
 743                 Rvalue::NullaryOp(null_op, ty) => {
 744                     assert!(
 745                         lval.layout()
 746                             .ty
 747                             .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all())
 748                     );
 749                     let layout = fx.layout_of(fx.monomorphize(ty));
 750                     let val = match null_op {
 751                         NullOp::SizeOf => layout.size.bytes(),
 752                         NullOp::AlignOf => layout.align.abi.bytes(),
 753                     };
 754                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), val.into());
 755                     lval.write_cvalue(fx, val);
 756                 }
 757                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 758                     AggregateKind::Array(_ty) => {
 759                         for (i, operand) in operands.iter().enumerate() {
 760                             let operand = codegen_operand(fx, operand);
 761                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 762                             let to = lval.place_index(fx, index);
 763                             to.write_cvalue(fx, operand);
 764                         }
 765                     }
 766                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 767                 },
 768             }
 769         }
 770         StatementKind::StorageLive(_)
 771         | StatementKind::StorageDead(_)
 772         | StatementKind::Deinit(_)
 773         | StatementKind::Nop
 774         | StatementKind::FakeRead(..)
 775         | StatementKind::Retag { .. }
 776         | StatementKind::AscribeUserType(..) => {}
 777
 778         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 779         StatementKind::CopyNonOverlapping(inner) => {
 780             let dst = codegen_operand(fx, &inner.dst);
 781             let pointee = dst
 782                 .layout()
 783                 .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 784                 .expect("Expected pointer");
 785             let dst = dst.load_scalar(fx);
 786             let src = codegen_operand(fx, &inner.src).load_scalar(fx);
 787             let count = codegen_operand(fx, &inner.count).load_scalar(fx);
 788             let elem_size: u64 = pointee.size.bytes();
 789             let bytes =
 790                 if elem_size != 1 { fx.bcx.ins().imul_imm(count, elem_size as i64) } else { count };
 791             fx.bcx.call_memcpy(fx.target_config, dst, src, bytes);
 792         }
 793     }
 794 }
 795
 796 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 797     match *place.layout().ty.kind() {
 798         ty::Array(_elem_ty, len) => {
 799             let len = fx.monomorphize(len).eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 800             fx.bcx.ins().iconst(fx.pointer_type, len)
 801         }
 802         ty::Slice(_elem_ty) => {
 803             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 804         }
 805         _ => bug!("Rvalue::Len({:?})", place),
 806     }
 807 }
 808
 809 pub(crate) fn codegen_place<'tcx>(
 810     fx: &mut FunctionCx<'_, '_, 'tcx>,
 811     place: Place<'tcx>,
 812 ) -> CPlace<'tcx> {
 813     let mut cplace = fx.get_local_place(place.local);
 814
 815     for elem in place.projection {
 816         match elem {
 817             PlaceElem::Deref => {
 818                 if cplace.layout().ty.is_box() {
 819                     cplace = cplace
 820                         .place_field(fx, Field::new(0)) // Box<T> -> Unique<T>
 821                         .place_field(fx, Field::new(0)) // Unique<T> -> NonNull<T>
 822                         .place_field(fx, Field::new(0)) // NonNull<T> -> *mut T
 823                         .place_deref(fx);
 824                 } else {
 825                     cplace = cplace.place_deref(fx);
 826                 }
 827             }
 828             PlaceElem::Field(field, _ty) => {
 829                 cplace = cplace.place_field(fx, field);
 830             }
 831             PlaceElem::Index(local) => {
 832                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 833                 cplace = cplace.place_index(fx, index);
 834             }
 835             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 836                 let offset: u64 = offset;
 837                 let index = if !from_end {
 838                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 839                 } else {
 840                     let len = codegen_array_len(fx, cplace);
 841                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 842                 };
 843                 cplace = cplace.place_index(fx, index);
 844             }
 845             PlaceElem::Subslice { from, to, from_end } => {
 846                 // These indices are generated by slice patterns.
 847                 // slice[from:-to] in Python terms.
 848
 849                 let from: u64 = from;
 850                 let to: u64 = to;
 851
 852                 match cplace.layout().ty.kind() {
 853                     ty::Array(elem_ty, _len) => {
 854                         assert!(!from_end, "array subslices are never `from_end`");
 855                         let elem_layout = fx.layout_of(*elem_ty);
 856                         let ptr = cplace.to_ptr();
 857                         cplace = CPlace::for_ptr(
 858                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 859                             fx.layout_of(fx.tcx.mk_array(*elem_ty, to - from)),
 860                         );
 861                     }
 862                     ty::Slice(elem_ty) => {
 863                         assert!(from_end, "slice subslices should be `from_end`");
 864                         let elem_layout = fx.layout_of(*elem_ty);
 865                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 866                         let len = len.unwrap();
 867                         cplace = CPlace::for_ptr_with_extra(
 868                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 869                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 870                             cplace.layout(),
 871                         );
 872                     }
 873                     _ => unreachable!(),
 874                 }
 875             }
 876             PlaceElem::Downcast(_adt_def, variant) => {
 877                 cplace = cplace.downcast_variant(fx, variant);
 878             }
 879         }
 880     }
 881
 882     cplace
 883 }
 884
 885 pub(crate) fn codegen_operand<'tcx>(
 886     fx: &mut FunctionCx<'_, '_, 'tcx>,
 887     operand: &Operand<'tcx>,
 888 ) -> CValue<'tcx> {
 889     match operand {
 890         Operand::Move(place) | Operand::Copy(place) => {
 891             let cplace = codegen_place(fx, *place);
 892             cplace.to_cvalue(fx)
 893         }
 894         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 895     }
 896 }
 897
 898 pub(crate) fn codegen_panic<'tcx>(
 899     fx: &mut FunctionCx<'_, '_, 'tcx>,
 900     msg_str: &str,
 901     source_info: mir::SourceInfo,
 902 ) {
 903     let location = fx.get_caller_location(source_info).load_scalar(fx);
 904
 905     let msg_ptr = fx.anonymous_str(msg_str);
 906     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 907     let args = [msg_ptr, msg_len, location];
 908
 909     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
 910 }
 911
 912 pub(crate) fn codegen_panic_inner<'tcx>(
 913     fx: &mut FunctionCx<'_, '_, 'tcx>,
 914     lang_item: rustc_hir::LangItem,
 915     args: &[Value],
 916     span: Span,
 917 ) {
 918     let def_id =
 919         fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
 920
 921     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 922     let symbol_name = fx.tcx.symbol_name(instance).name;
 923
 924     fx.lib_call(
 925         &*symbol_name,
 926         vec![
 927             AbiParam::new(fx.pointer_type),
 928             AbiParam::new(fx.pointer_type),
 929             AbiParam::new(fx.pointer_type),
 930         ],
 931         vec![],
 932         args,
 933     );
 934
 935     fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 936 }