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 use rustc_middle::ty::SymbolName;
   9
  10 use indexmap::IndexSet;
  11
  12 use crate::constant::ConstantCx;
  13 use crate::prelude::*;
  14 use crate::pretty_clif::CommentWriter;
  15
  16 struct CodegenedFunction<'tcx> {
  17     instance: Instance<'tcx>,
  18     symbol_name: SymbolName<'tcx>,
  19     func_id: FuncId,
  20     func: Function,
  21     clif_comments: CommentWriter,
  22     source_info_set: IndexSet<SourceInfo>,
  23     local_map: IndexVec<mir::Local, CPlace<'tcx>>,
  24 }
  25
  26 pub(crate) fn codegen_and_compile_fn<'tcx>(
  27     cx: &mut crate::CodegenCx<'tcx>,
  28     cached_context: &mut Context,
  29     module: &mut dyn Module,
  30     instance: Instance<'tcx>,
  31 ) {
  32     let tcx = cx.tcx;
  33     let _inst_guard =
  34         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  35
  36     let cached_func = std::mem::replace(&mut cached_context.func, Function::new());
  37     let codegened_func = codegen_fn(cx, cached_func, module, instance);
  38
  39     compile_fn(cx, cached_context, module, codegened_func);
  40 }
  41
  42 fn codegen_fn<'tcx>(
  43     cx: &mut crate::CodegenCx<'tcx>,
  44     cached_func: Function,
  45     module: &mut dyn Module,
  46     instance: Instance<'tcx>,
  47 ) -> CodegenedFunction<'tcx> {
  48     debug_assert!(!instance.substs.needs_infer());
  49
  50     let tcx = cx.tcx;
  51
  52     let mir = tcx.instance_mir(instance.def);
  53     let _mir_guard = crate::PrintOnPanic(|| {
  54         let mut buf = Vec::new();
  55         with_no_trimmed_paths!({
  56             rustc_middle::mir::pretty::write_mir_fn(tcx, mir, &mut |_, _| Ok(()), &mut buf)
  57                 .unwrap();
  58         });
  59         String::from_utf8_lossy(&buf).into_owned()
  60     });
  61
  62     // Declare function
  63     let symbol_name = tcx.symbol_name(instance);
  64     let sig = get_function_sig(tcx, module.isa().triple(), instance);
  65     let func_id = module.declare_function(symbol_name.name, Linkage::Local, &sig).unwrap();
  66
  67     // Make the FunctionBuilder
  68     let mut func_ctx = FunctionBuilderContext::new();
  69     let mut func = cached_func;
  70     func.clear();
  71     func.name = ExternalName::user(0, func_id.as_u32());
  72     func.signature = sig;
  73     func.collect_debug_info();
  74
  75     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  76
  77     // Predefine blocks
  78     let start_block = bcx.create_block();
  79     let block_map: IndexVec<BasicBlock, Block> =
  80         (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  81
  82     // Make FunctionCx
  83     let target_config = module.target_config();
  84     let pointer_type = target_config.pointer_type();
  85     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  86
  87     let mut fx = FunctionCx {
  88         cx,
  89         module,
  90         tcx,
  91         target_config,
  92         pointer_type,
  93         constants_cx: ConstantCx::new(),
  94
  95         instance,
  96         symbol_name,
  97         mir,
  98         fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())),
  99
 100         bcx,
 101         block_map,
 102         local_map: IndexVec::with_capacity(mir.local_decls.len()),
 103         caller_location: None, // set by `codegen_fn_prelude`
 104
 105         clif_comments,
 106         source_info_set: indexmap::IndexSet::new(),
 107         next_ssa_var: 0,
 108     };
 109
 110     tcx.sess.time("codegen clif ir", || codegen_fn_body(&mut fx, start_block));
 111
 112     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 113     let instance = fx.instance;
 114     let clif_comments = fx.clif_comments;
 115     let source_info_set = fx.source_info_set;
 116     let local_map = fx.local_map;
 117
 118     fx.constants_cx.finalize(fx.tcx, &mut *fx.module);
 119
 120     crate::pretty_clif::write_clif_file(
 121         tcx,
 122         "unopt",
 123         module.isa(),
 124         instance,
 125         &func,
 126         &clif_comments,
 127     );
 128
 129     // Verify function
 130     verify_func(tcx, &clif_comments, &func);
 131
 132     CodegenedFunction {
 133         instance,
 134         symbol_name,
 135         func_id,
 136         func,
 137         clif_comments,
 138         source_info_set,
 139         local_map,
 140     }
 141 }
 142
 143 fn compile_fn<'tcx>(
 144     cx: &mut crate::CodegenCx<'tcx>,
 145     cached_context: &mut Context,
 146     module: &mut dyn Module,
 147     codegened_func: CodegenedFunction<'tcx>,
 148 ) {
 149     let tcx = cx.tcx;
 150
 151     let mut clif_comments = codegened_func.clif_comments;
 152
 153     // Store function in context
 154     let context = cached_context;
 155     context.clear();
 156     context.func = codegened_func.func;
 157
 158     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 159     // instruction, which doesn't have an encoding.
 160     context.compute_cfg();
 161     context.compute_domtree();
 162     context.eliminate_unreachable_code(module.isa()).unwrap();
 163     context.dce(module.isa()).unwrap();
 164     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 165     // invalidate it when it would change.
 166     context.domtree.clear();
 167
 168     // Perform rust specific optimizations
 169     tcx.sess.time("optimize clif ir", || {
 170         crate::optimize::optimize_function(
 171             tcx,
 172             module.isa(),
 173             codegened_func.instance,
 174             context,
 175             &mut clif_comments,
 176         );
 177     });
 178
 179     #[cfg(any())] // This is never true
 180     let _clif_guard = {
 181         use std::fmt::Write;
 182
 183         let func_clone = context.func.clone();
 184         let clif_comments_clone = clif_comments.clone();
 185         let mut clif = String::new();
 186         for flag in module.isa().flags().iter() {
 187             writeln!(clif, "set {}", flag).unwrap();
 188         }
 189         write!(clif, "target {}", module.isa().triple().architecture.to_string()).unwrap();
 190         for isa_flag in module.isa().isa_flags().iter() {
 191             write!(clif, " {}", isa_flag).unwrap();
 192         }
 193         writeln!(clif, "\n").unwrap();
 194         crate::PrintOnPanic(move || {
 195             let mut clif = clif.clone();
 196             ::cranelift_codegen::write::decorate_function(
 197                 &mut &clif_comments_clone,
 198                 &mut clif,
 199                 &func_clone,
 200             )
 201             .unwrap();
 202             clif
 203         })
 204     };
 205
 206     // Define function
 207     tcx.sess.time("define function", || {
 208         context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 209         module.define_function(codegened_func.func_id, context).unwrap();
 210     });
 211
 212     // Write optimized function to file for debugging
 213     crate::pretty_clif::write_clif_file(
 214         tcx,
 215         "opt",
 216         module.isa(),
 217         codegened_func.instance,
 218         &context.func,
 219         &clif_comments,
 220     );
 221
 222     if let Some(disasm) = &context.mach_compile_result.as_ref().unwrap().disasm {
 223         crate::pretty_clif::write_ir_file(
 224             tcx,
 225             || format!("{}.vcode", tcx.symbol_name(codegened_func.instance).name),
 226             |file| file.write_all(disasm.as_bytes()),
 227         )
 228     }
 229
 230     // Define debuginfo for function
 231     let isa = module.isa();
 232     let debug_context = &mut cx.debug_context;
 233     let unwind_context = &mut cx.unwind_context;
 234     tcx.sess.time("generate debug info", || {
 235         if let Some(debug_context) = debug_context {
 236             debug_context.define_function(
 237                 codegened_func.instance,
 238                 codegened_func.func_id,
 239                 codegened_func.symbol_name.name,
 240                 isa,
 241                 context,
 242                 &codegened_func.source_info_set,
 243                 codegened_func.local_map,
 244             );
 245         }
 246         unwind_context.add_function(codegened_func.func_id, &context, isa);
 247     });
 248 }
 249
 250 pub(crate) fn verify_func(
 251     tcx: TyCtxt<'_>,
 252     writer: &crate::pretty_clif::CommentWriter,
 253     func: &Function,
 254 ) {
 255     tcx.sess.time("verify clif ir", || {
 256         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 257         match cranelift_codegen::verify_function(&func, &flags) {
 258             Ok(_) => {}
 259             Err(err) => {
 260                 tcx.sess.err(&format!("{:?}", err));
 261                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 262                     &func,
 263                     Some(Box::new(writer)),
 264                     err,
 265                 );
 266                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 267             }
 268         }
 269     });
 270 }
 271
 272 fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
 273     if !crate::constant::check_constants(fx) {
 274         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
 275         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
 276         // compilation should have been aborted
 277         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 278         return;
 279     }
 280
 281     let arg_uninhabited = fx
 282         .mir
 283         .args_iter()
 284         .any(|arg| fx.layout_of(fx.monomorphize(fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
 285     if arg_uninhabited {
 286         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
 287         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
 288         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 289         return;
 290     }
 291     fx.tcx.sess.time("codegen prelude", || crate::abi::codegen_fn_prelude(fx, start_block));
 292
 293     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 294         let block = fx.get_block(bb);
 295         fx.bcx.switch_to_block(block);
 296
 297         if bb_data.is_cleanup {
 298             // Unwinding after panicking is not supported
 299             continue;
 300
 301             // FIXME Once unwinding is supported and Cranelift supports marking blocks as cold, do
 302             // so for cleanup blocks.
 303         }
 304
 305         fx.bcx.ins().nop();
 306         for stmt in &bb_data.statements {
 307             fx.set_debug_loc(stmt.source_info);
 308             codegen_stmt(fx, block, stmt);
 309         }
 310
 311         if fx.clif_comments.enabled() {
 312             let mut terminator_head = "\n".to_string();
 313             with_no_trimmed_paths!({
 314                 bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 315             });
 316             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 317             fx.add_comment(inst, terminator_head);
 318         }
 319
 320         let source_info = bb_data.terminator().source_info;
 321         fx.set_debug_loc(source_info);
 322
 323         match &bb_data.terminator().kind {
 324             TerminatorKind::Goto { target } => {
 325                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 326                     let mut can_immediately_return = true;
 327                     for stmt in &fx.mir[*target].statements {
 328                         if let StatementKind::StorageDead(_) = stmt.kind {
 329                         } else {
 330                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 331                             can_immediately_return = false;
 332                             break;
 333                         }
 334                     }
 335
 336                     if can_immediately_return {
 337                         crate::abi::codegen_return(fx);
 338                         continue;
 339                     }
 340                 }
 341
 342                 let block = fx.get_block(*target);
 343                 fx.bcx.ins().jump(block, &[]);
 344             }
 345             TerminatorKind::Return => {
 346                 crate::abi::codegen_return(fx);
 347             }
 348             TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
 349                 if !fx.tcx.sess.overflow_checks() {
 350                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 351                         let target = fx.get_block(*target);
 352                         fx.bcx.ins().jump(target, &[]);
 353                         continue;
 354                     }
 355                 }
 356                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 357
 358                 let target = fx.get_block(*target);
 359                 let failure = fx.bcx.create_block();
 360                 fx.bcx.set_cold_block(failure);
 361
 362                 if *expected {
 363                     fx.bcx.ins().brz(cond, failure, &[]);
 364                 } else {
 365                     fx.bcx.ins().brnz(cond, failure, &[]);
 366                 };
 367                 fx.bcx.ins().jump(target, &[]);
 368
 369                 fx.bcx.switch_to_block(failure);
 370                 fx.bcx.ins().nop();
 371
 372                 match msg {
 373                     AssertKind::BoundsCheck { ref len, ref index } => {
 374                         let len = codegen_operand(fx, len).load_scalar(fx);
 375                         let index = codegen_operand(fx, index).load_scalar(fx);
 376                         let location = fx.get_caller_location(source_info).load_scalar(fx);
 377
 378                         codegen_panic_inner(
 379                             fx,
 380                             rustc_hir::LangItem::PanicBoundsCheck,
 381                             &[index, len, location],
 382                             source_info.span,
 383                         );
 384                     }
 385                     _ => {
 386                         let msg_str = msg.description();
 387                         codegen_panic(fx, msg_str, source_info);
 388                     }
 389                 }
 390             }
 391
 392             TerminatorKind::SwitchInt { discr, switch_ty, targets } => {
 393                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 394
 395                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 396                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 397                 if use_bool_opt {
 398                     assert_eq!(targets.iter().count(), 1);
 399                     let (then_value, then_block) = targets.iter().next().unwrap();
 400                     let then_block = fx.get_block(then_block);
 401                     let else_block = fx.get_block(targets.otherwise());
 402                     let test_zero = match then_value {
 403                         0 => true,
 404                         1 => false,
 405                         _ => unreachable!("{:?}", targets),
 406                     };
 407
 408                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 409                     let (discr, is_inverted) =
 410                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 411                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 412                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 413                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 414                         &fx.bcx, discr, test_zero,
 415                     ) {
 416                         if taken {
 417                             fx.bcx.ins().jump(then_block, &[]);
 418                         } else {
 419                             fx.bcx.ins().jump(else_block, &[]);
 420                         }
 421                     } else {
 422                         if test_zero {
 423                             fx.bcx.ins().brz(discr, then_block, &[]);
 424                             fx.bcx.ins().jump(else_block, &[]);
 425                         } else {
 426                             fx.bcx.ins().brnz(discr, then_block, &[]);
 427                             fx.bcx.ins().jump(else_block, &[]);
 428                         }
 429                     }
 430                 } else {
 431                     let mut switch = ::cranelift_frontend::Switch::new();
 432                     for (value, block) in targets.iter() {
 433                         let block = fx.get_block(block);
 434                         switch.set_entry(value, block);
 435                     }
 436                     let otherwise_block = fx.get_block(targets.otherwise());
 437                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 438                 }
 439             }
 440             TerminatorKind::Call {
 441                 func,
 442                 args,
 443                 destination,
 444                 target,
 445                 fn_span,
 446                 cleanup: _,
 447                 from_hir_call: _,
 448             } => {
 449                 fx.tcx.sess.time("codegen call", || {
 450                     crate::abi::codegen_terminator_call(
 451                         fx,
 452                         mir::SourceInfo { span: *fn_span, ..source_info },
 453                         func,
 454                         args,
 455                         *destination,
 456                         *target,
 457                     )
 458                 });
 459             }
 460             TerminatorKind::InlineAsm {
 461                 template,
 462                 operands,
 463                 options,
 464                 destination,
 465                 line_spans: _,
 466                 cleanup: _,
 467             } => {
 468                 if options.contains(InlineAsmOptions::MAY_UNWIND) {
 469                     fx.tcx.sess.span_fatal(
 470                         source_info.span,
 471                         "cranelift doesn't support unwinding from inline assembly.",
 472                     );
 473                 }
 474
 475                 crate::inline_asm::codegen_inline_asm(
 476                     fx,
 477                     source_info.span,
 478                     template,
 479                     operands,
 480                     *options,
 481                     *destination,
 482                 );
 483             }
 484             TerminatorKind::Resume | TerminatorKind::Abort => {
 485                 // FIXME implement unwinding
 486                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 487             }
 488             TerminatorKind::Unreachable => {
 489                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 490             }
 491             TerminatorKind::Yield { .. }
 492             | TerminatorKind::FalseEdge { .. }
 493             | TerminatorKind::FalseUnwind { .. }
 494             | TerminatorKind::DropAndReplace { .. }
 495             | TerminatorKind::GeneratorDrop => {
 496                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 497             }
 498             TerminatorKind::Drop { place, target, unwind: _ } => {
 499                 let drop_place = codegen_place(fx, *place);
 500                 crate::abi::codegen_drop(fx, source_info, drop_place);
 501
 502                 let target_block = fx.get_block(*target);
 503                 fx.bcx.ins().jump(target_block, &[]);
 504             }
 505         };
 506     }
 507
 508     fx.bcx.seal_all_blocks();
 509     fx.bcx.finalize();
 510 }
 511
 512 fn codegen_stmt<'tcx>(
 513     fx: &mut FunctionCx<'_, '_, 'tcx>,
 514     #[allow(unused_variables)] cur_block: Block,
 515     stmt: &Statement<'tcx>,
 516 ) {
 517     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 518
 519     fx.set_debug_loc(stmt.source_info);
 520
 521     #[cfg(any())] // This is never true
 522     match &stmt.kind {
 523         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 524         _ => {
 525             if fx.clif_comments.enabled() {
 526                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 527                 fx.add_comment(inst, format!("{:?}", stmt));
 528             }
 529         }
 530     }
 531
 532     match &stmt.kind {
 533         StatementKind::SetDiscriminant { place, variant_index } => {
 534             let place = codegen_place(fx, **place);
 535             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 536         }
 537         StatementKind::Assign(to_place_and_rval) => {
 538             let lval = codegen_place(fx, to_place_and_rval.0);
 539             let dest_layout = lval.layout();
 540             match to_place_and_rval.1 {
 541                 Rvalue::Use(ref operand) => {
 542                     let val = codegen_operand(fx, operand);
 543                     lval.write_cvalue(fx, val);
 544                 }
 545                 Rvalue::CopyForDeref(place) => {
 546                     let cplace = codegen_place(fx, place);
 547                     let val = cplace.to_cvalue(fx);
 548                     lval.write_cvalue(fx, val)
 549                 }
 550                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 551                     let place = codegen_place(fx, place);
 552                     let ref_ = place.place_ref(fx, lval.layout());
 553                     lval.write_cvalue(fx, ref_);
 554                 }
 555                 Rvalue::ThreadLocalRef(def_id) => {
 556                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 557                     lval.write_cvalue(fx, val);
 558                 }
 559                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 560                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 561                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 562
 563                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 564                     lval.write_cvalue(fx, res);
 565                 }
 566                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 567                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 568                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 569
 570                     let res = if !fx.tcx.sess.overflow_checks() {
 571                         let val =
 572                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 573                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 574                         CValue::by_val_pair(val, is_overflow, lval.layout())
 575                     } else {
 576                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 577                     };
 578
 579                     lval.write_cvalue(fx, res);
 580                 }
 581                 Rvalue::UnaryOp(un_op, ref operand) => {
 582                     let operand = codegen_operand(fx, operand);
 583                     let layout = operand.layout();
 584                     let val = operand.load_scalar(fx);
 585                     let res = match un_op {
 586                         UnOp::Not => match layout.ty.kind() {
 587                             ty::Bool => {
 588                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 589                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 590                             }
 591                             ty::Uint(_) | ty::Int(_) => {
 592                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 593                             }
 594                             _ => unreachable!("un op Not for {:?}", layout.ty),
 595                         },
 596                         UnOp::Neg => match layout.ty.kind() {
 597                             ty::Int(IntTy::I128) => {
 598                                 // FIXME remove this case once ineg.i128 works
 599                                 let zero =
 600                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 601                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 602                             }
 603                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 604                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 605                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 606                         },
 607                     };
 608                     lval.write_cvalue(fx, res);
 609                 }
 610                 Rvalue::Cast(
 611                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 612                     ref operand,
 613                     to_ty,
 614                 ) => {
 615                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 616                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 617                     match *from_ty.kind() {
 618                         ty::FnDef(def_id, substs) => {
 619                             let func_ref = fx.get_function_ref(
 620                                 Instance::resolve_for_fn_ptr(
 621                                     fx.tcx,
 622                                     ParamEnv::reveal_all(),
 623                                     def_id,
 624                                     substs,
 625                                 )
 626                                 .unwrap()
 627                                 .polymorphize(fx.tcx),
 628                             );
 629                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 630                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 631                         }
 632                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 633                     }
 634                 }
 635                 Rvalue::Cast(
 636                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 637                     ref operand,
 638                     to_ty,
 639                 )
 640                 | Rvalue::Cast(
 641                     CastKind::Pointer(PointerCast::MutToConstPointer),
 642                     ref operand,
 643                     to_ty,
 644                 )
 645                 | Rvalue::Cast(
 646                     CastKind::Pointer(PointerCast::ArrayToPointer),
 647                     ref operand,
 648                     to_ty,
 649                 ) => {
 650                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 651                     let operand = codegen_operand(fx, operand);
 652                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 653                 }
 654                 Rvalue::Cast(
 655                     CastKind::Misc
 656                     | CastKind::PointerExposeAddress
 657                     | CastKind::PointerFromExposedAddress,
 658                     ref operand,
 659                     to_ty,
 660                 ) => {
 661                     let operand = codegen_operand(fx, operand);
 662                     let from_ty = operand.layout().ty;
 663                     let to_ty = fx.monomorphize(to_ty);
 664
 665                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 666                         ty.builtin_deref(true)
 667                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 668                                 has_ptr_meta(fx.tcx, pointee_ty)
 669                             })
 670                             .unwrap_or(false)
 671                     }
 672
 673                     if is_fat_ptr(fx, from_ty) {
 674                         if is_fat_ptr(fx, to_ty) {
 675                             // fat-ptr -> fat-ptr
 676                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 677                         } else {
 678                             // fat-ptr -> thin-ptr
 679                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 680                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 681                         }
 682                     } else {
 683                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 684                         let from = operand.load_scalar(fx);
 685
 686                         let res = clif_int_or_float_cast(
 687                             fx,
 688                             from,
 689                             type_sign(from_ty),
 690                             to_clif_ty,
 691                             type_sign(to_ty),
 692                         );
 693                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 694                     }
 695                 }
 696                 Rvalue::Cast(
 697                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 698                     ref operand,
 699                     _to_ty,
 700                 ) => {
 701                     let operand = codegen_operand(fx, operand);
 702                     match *operand.layout().ty.kind() {
 703                         ty::Closure(def_id, substs) => {
 704                             let instance = Instance::resolve_closure(
 705                                 fx.tcx,
 706                                 def_id,
 707                                 substs,
 708                                 ty::ClosureKind::FnOnce,
 709                             )
 710                             .expect("failed to normalize and resolve closure during codegen")
 711                             .polymorphize(fx.tcx);
 712                             let func_ref = fx.get_function_ref(instance);
 713                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 714                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 715                         }
 716                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 717                     }
 718                 }
 719                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 720                     let operand = codegen_operand(fx, operand);
 721                     operand.unsize_value(fx, lval);
 722                 }
 723                 Rvalue::Discriminant(place) => {
 724                     let place = codegen_place(fx, place);
 725                     let value = place.to_cvalue(fx);
 726                     crate::discriminant::codegen_get_discriminant(fx, lval, value, dest_layout);
 727                 }
 728                 Rvalue::Repeat(ref operand, times) => {
 729                     let operand = codegen_operand(fx, operand);
 730                     let times = fx
 731                         .monomorphize(times)
 732                         .eval(fx.tcx, ParamEnv::reveal_all())
 733                         .kind()
 734                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 735                         .unwrap();
 736                     if operand.layout().size.bytes() == 0 {
 737                         // Do nothing for ZST's
 738                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 739                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 740                         // FIXME use emit_small_memset where possible
 741                         let addr = lval.to_ptr().get_addr(fx);
 742                         let val = operand.load_scalar(fx);
 743                         fx.bcx.call_memset(fx.target_config, addr, val, times);
 744                     } else {
 745                         let loop_block = fx.bcx.create_block();
 746                         let loop_block2 = fx.bcx.create_block();
 747                         let done_block = fx.bcx.create_block();
 748                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 749                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 750                         fx.bcx.ins().jump(loop_block, &[zero]);
 751
 752                         fx.bcx.switch_to_block(loop_block);
 753                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 754                         fx.bcx.ins().brnz(done, done_block, &[]);
 755                         fx.bcx.ins().jump(loop_block2, &[]);
 756
 757                         fx.bcx.switch_to_block(loop_block2);
 758                         let to = lval.place_index(fx, index);
 759                         to.write_cvalue(fx, operand);
 760                         let index = fx.bcx.ins().iadd_imm(index, 1);
 761                         fx.bcx.ins().jump(loop_block, &[index]);
 762
 763                         fx.bcx.switch_to_block(done_block);
 764                         fx.bcx.ins().nop();
 765                     }
 766                 }
 767                 Rvalue::Len(place) => {
 768                     let place = codegen_place(fx, place);
 769                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 770                     let len = codegen_array_len(fx, place);
 771                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 772                 }
 773                 Rvalue::ShallowInitBox(ref operand, content_ty) => {
 774                     let content_ty = fx.monomorphize(content_ty);
 775                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 776                     let operand = codegen_operand(fx, operand);
 777                     let operand = operand.load_scalar(fx);
 778                     lval.write_cvalue(fx, CValue::by_val(operand, box_layout));
 779                 }
 780                 Rvalue::NullaryOp(null_op, ty) => {
 781                     assert!(
 782                         lval.layout()
 783                             .ty
 784                             .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all())
 785                     );
 786                     let layout = fx.layout_of(fx.monomorphize(ty));
 787                     let val = match null_op {
 788                         NullOp::SizeOf => layout.size.bytes(),
 789                         NullOp::AlignOf => layout.align.abi.bytes(),
 790                     };
 791                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), val.into());
 792                     lval.write_cvalue(fx, val);
 793                 }
 794                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 795                     AggregateKind::Array(_ty) => {
 796                         for (i, operand) in operands.iter().enumerate() {
 797                             let operand = codegen_operand(fx, operand);
 798                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 799                             let to = lval.place_index(fx, index);
 800                             to.write_cvalue(fx, operand);
 801                         }
 802                     }
 803                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 804                 },
 805             }
 806         }
 807         StatementKind::StorageLive(_)
 808         | StatementKind::StorageDead(_)
 809         | StatementKind::Deinit(_)
 810         | StatementKind::Nop
 811         | StatementKind::FakeRead(..)
 812         | StatementKind::Retag { .. }
 813         | StatementKind::AscribeUserType(..) => {}
 814
 815         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 816         StatementKind::CopyNonOverlapping(inner) => {
 817             let dst = codegen_operand(fx, &inner.dst);
 818             let pointee = dst
 819                 .layout()
 820                 .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 821                 .expect("Expected pointer");
 822             let dst = dst.load_scalar(fx);
 823             let src = codegen_operand(fx, &inner.src).load_scalar(fx);
 824             let count = codegen_operand(fx, &inner.count).load_scalar(fx);
 825             let elem_size: u64 = pointee.size.bytes();
 826             let bytes =
 827                 if elem_size != 1 { fx.bcx.ins().imul_imm(count, elem_size as i64) } else { count };
 828             fx.bcx.call_memcpy(fx.target_config, dst, src, bytes);
 829         }
 830     }
 831 }
 832
 833 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 834     match *place.layout().ty.kind() {
 835         ty::Array(_elem_ty, len) => {
 836             let len = fx.monomorphize(len).eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 837             fx.bcx.ins().iconst(fx.pointer_type, len)
 838         }
 839         ty::Slice(_elem_ty) => {
 840             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 841         }
 842         _ => bug!("Rvalue::Len({:?})", place),
 843     }
 844 }
 845
 846 pub(crate) fn codegen_place<'tcx>(
 847     fx: &mut FunctionCx<'_, '_, 'tcx>,
 848     place: Place<'tcx>,
 849 ) -> CPlace<'tcx> {
 850     let mut cplace = fx.get_local_place(place.local);
 851
 852     for elem in place.projection {
 853         match elem {
 854             PlaceElem::Deref => {
 855                 cplace = cplace.place_deref(fx);
 856             }
 857             PlaceElem::Field(field, _ty) => {
 858                 cplace = cplace.place_field(fx, field);
 859             }
 860             PlaceElem::Index(local) => {
 861                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 862                 cplace = cplace.place_index(fx, index);
 863             }
 864             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 865                 let offset: u64 = offset;
 866                 let index = if !from_end {
 867                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 868                 } else {
 869                     let len = codegen_array_len(fx, cplace);
 870                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 871                 };
 872                 cplace = cplace.place_index(fx, index);
 873             }
 874             PlaceElem::Subslice { from, to, from_end } => {
 875                 // These indices are generated by slice patterns.
 876                 // slice[from:-to] in Python terms.
 877
 878                 let from: u64 = from;
 879                 let to: u64 = to;
 880
 881                 match cplace.layout().ty.kind() {
 882                     ty::Array(elem_ty, _len) => {
 883                         assert!(!from_end, "array subslices are never `from_end`");
 884                         let elem_layout = fx.layout_of(*elem_ty);
 885                         let ptr = cplace.to_ptr();
 886                         cplace = CPlace::for_ptr(
 887                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 888                             fx.layout_of(fx.tcx.mk_array(*elem_ty, to - from)),
 889                         );
 890                     }
 891                     ty::Slice(elem_ty) => {
 892                         assert!(from_end, "slice subslices should be `from_end`");
 893                         let elem_layout = fx.layout_of(*elem_ty);
 894                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 895                         let len = len.unwrap();
 896                         cplace = CPlace::for_ptr_with_extra(
 897                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 898                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 899                             cplace.layout(),
 900                         );
 901                     }
 902                     _ => unreachable!(),
 903                 }
 904             }
 905             PlaceElem::Downcast(_adt_def, variant) => {
 906                 cplace = cplace.downcast_variant(fx, variant);
 907             }
 908         }
 909     }
 910
 911     cplace
 912 }
 913
 914 pub(crate) fn codegen_operand<'tcx>(
 915     fx: &mut FunctionCx<'_, '_, 'tcx>,
 916     operand: &Operand<'tcx>,
 917 ) -> CValue<'tcx> {
 918     match operand {
 919         Operand::Move(place) | Operand::Copy(place) => {
 920             let cplace = codegen_place(fx, *place);
 921             cplace.to_cvalue(fx)
 922         }
 923         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 924     }
 925 }
 926
 927 pub(crate) fn codegen_panic<'tcx>(
 928     fx: &mut FunctionCx<'_, '_, 'tcx>,
 929     msg_str: &str,
 930     source_info: mir::SourceInfo,
 931 ) {
 932     let location = fx.get_caller_location(source_info).load_scalar(fx);
 933
 934     let msg_ptr = fx.anonymous_str(msg_str);
 935     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 936     let args = [msg_ptr, msg_len, location];
 937
 938     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
 939 }
 940
 941 pub(crate) fn codegen_panic_inner<'tcx>(
 942     fx: &mut FunctionCx<'_, '_, 'tcx>,
 943     lang_item: rustc_hir::LangItem,
 944     args: &[Value],
 945     span: Span,
 946 ) {
 947     let def_id =
 948         fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
 949
 950     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 951     let symbol_name = fx.tcx.symbol_name(instance).name;
 952
 953     fx.lib_call(
 954         &*symbol_name,
 955         vec![
 956             AbiParam::new(fx.pointer_type),
 957             AbiParam::new(fx.pointer_type),
 958             AbiParam::new(fx.pointer_type),
 959         ],
 960         vec![],
 961         args,
 962     );
 963
 964     fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 965 }