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