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 cranelift_codegen::ir::UserFuncName;
  10
  11 use crate::constant::ConstantCx;
  12 use crate::debuginfo::FunctionDebugContext;
  13 use crate::prelude::*;
  14 use crate::pretty_clif::CommentWriter;
  15
  16 pub(crate) struct CodegenedFunction {
  17     symbol_name: String,
  18     func_id: FuncId,
  19     func: Function,
  20     clif_comments: CommentWriter,
  21     func_debug_cx: Option<FunctionDebugContext>,
  22 }
  23
  24 pub(crate) fn codegen_fn<'tcx>(
  25     tcx: TyCtxt<'tcx>,
  26     cx: &mut crate::CodegenCx,
  27     cached_func: Function,
  28     module: &mut dyn Module,
  29     instance: Instance<'tcx>,
  30 ) -> CodegenedFunction {
  31     debug_assert!(!instance.substs.needs_infer());
  32
  33     let symbol_name = tcx.symbol_name(instance).name.to_string();
  34     let _timer = tcx.prof.generic_activity_with_arg("codegen fn", &*symbol_name);
  35
  36     let mir = tcx.instance_mir(instance.def);
  37     let _mir_guard = crate::PrintOnPanic(|| {
  38         let mut buf = Vec::new();
  39         with_no_trimmed_paths!({
  40             rustc_middle::mir::pretty::write_mir_fn(tcx, mir, &mut |_, _| Ok(()), &mut buf)
  41                 .unwrap();
  42         });
  43         String::from_utf8_lossy(&buf).into_owned()
  44     });
  45
  46     // Declare function
  47     let sig = get_function_sig(tcx, module.target_config().default_call_conv, instance);
  48     let func_id = module.declare_function(&symbol_name, Linkage::Local, &sig).unwrap();
  49
  50     // Make the FunctionBuilder
  51     let mut func_ctx = FunctionBuilderContext::new();
  52     let mut func = cached_func;
  53     func.clear();
  54     func.name = UserFuncName::user(0, func_id.as_u32());
  55     func.signature = sig;
  56     func.collect_debug_info();
  57
  58     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  59
  60     // Predefine blocks
  61     let start_block = bcx.create_block();
  62     let block_map: IndexVec<BasicBlock, Block> =
  63         (0..mir.basic_blocks.len()).map(|_| bcx.create_block()).collect();
  64
  65     // Make FunctionCx
  66     let target_config = module.target_config();
  67     let pointer_type = target_config.pointer_type();
  68     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  69
  70     let func_debug_cx = if let Some(debug_context) = &mut cx.debug_context {
  71         Some(debug_context.define_function(tcx, &symbol_name, mir.span))
  72     } else {
  73         None
  74     };
  75
  76     let mut fx = FunctionCx {
  77         cx,
  78         module,
  79         tcx,
  80         target_config,
  81         pointer_type,
  82         constants_cx: ConstantCx::new(),
  83         func_debug_cx,
  84
  85         instance,
  86         symbol_name,
  87         mir,
  88         fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())),
  89
  90         bcx,
  91         block_map,
  92         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  93         caller_location: None, // set by `codegen_fn_prelude`
  94
  95         clif_comments,
  96         last_source_file: None,
  97         next_ssa_var: 0,
  98     };
  99
 100     tcx.prof.generic_activity("codegen clif ir").run(|| codegen_fn_body(&mut fx, start_block));
 101     fx.bcx.seal_all_blocks();
 102     fx.bcx.finalize();
 103
 104     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 105     let symbol_name = fx.symbol_name;
 106     let clif_comments = fx.clif_comments;
 107     let func_debug_cx = fx.func_debug_cx;
 108
 109     fx.constants_cx.finalize(fx.tcx, &mut *fx.module);
 110
 111     if cx.should_write_ir {
 112         crate::pretty_clif::write_clif_file(
 113             tcx.output_filenames(()),
 114             &symbol_name,
 115             "unopt",
 116             module.isa(),
 117             &func,
 118             &clif_comments,
 119         );
 120     }
 121
 122     // Verify function
 123     verify_func(tcx, &clif_comments, &func);
 124
 125     CodegenedFunction { symbol_name, func_id, func, clif_comments, func_debug_cx }
 126 }
 127
 128 pub(crate) fn compile_fn(
 129     cx: &mut crate::CodegenCx,
 130     cached_context: &mut Context,
 131     module: &mut dyn Module,
 132     codegened_func: CodegenedFunction,
 133 ) {
 134     let _timer =
 135         cx.profiler.generic_activity_with_arg("compile function", &*codegened_func.symbol_name);
 136
 137     let clif_comments = codegened_func.clif_comments;
 138
 139     // Store function in context
 140     let context = cached_context;
 141     context.clear();
 142     context.func = codegened_func.func;
 143
 144     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 145     // instruction, which doesn't have an encoding.
 146     context.compute_cfg();
 147     context.compute_domtree();
 148     context.eliminate_unreachable_code(module.isa()).unwrap();
 149     context.dce(module.isa()).unwrap();
 150     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 151     // invalidate it when it would change.
 152     context.domtree.clear();
 153
 154     #[cfg(any())] // This is never true
 155     let _clif_guard = {
 156         use std::fmt::Write;
 157
 158         let func_clone = context.func.clone();
 159         let clif_comments_clone = clif_comments.clone();
 160         let mut clif = String::new();
 161         for flag in module.isa().flags().iter() {
 162             writeln!(clif, "set {}", flag).unwrap();
 163         }
 164         write!(clif, "target {}", module.isa().triple().architecture.to_string()).unwrap();
 165         for isa_flag in module.isa().isa_flags().iter() {
 166             write!(clif, " {}", isa_flag).unwrap();
 167         }
 168         writeln!(clif, "\n").unwrap();
 169         crate::PrintOnPanic(move || {
 170             let mut clif = clif.clone();
 171             ::cranelift_codegen::write::decorate_function(
 172                 &mut &clif_comments_clone,
 173                 &mut clif,
 174                 &func_clone,
 175             )
 176             .unwrap();
 177             clif
 178         })
 179     };
 180
 181     // Define function
 182     cx.profiler.generic_activity("define function").run(|| {
 183         context.want_disasm = cx.should_write_ir;
 184         module.define_function(codegened_func.func_id, context).unwrap();
 185
 186         if cx.profiler.enabled() {
 187             let mut recording_args = false;
 188             cx.profiler
 189                 .generic_activity_with_arg_recorder(
 190                     "define function (clif pass timings)",
 191                     |recorder| {
 192                         let pass_times = cranelift_codegen::timing::take_current();
 193                         // Replace newlines with | as measureme doesn't allow control characters like
 194                         // newlines inside strings.
 195                         recorder.record_arg(format!("{}", pass_times).replace("\n", " | "));
 196                         recording_args = true;
 197                     },
 198                 )
 199                 .run(|| {
 200                     if recording_args {
 201                         // Wait a tiny bit to ensure chrome's profiler doesn't hide the event
 202                         std::thread::sleep(std::time::Duration::from_nanos(2))
 203                     }
 204                 });
 205         }
 206     });
 207
 208     if cx.should_write_ir {
 209         // Write optimized function to file for debugging
 210         crate::pretty_clif::write_clif_file(
 211             &cx.output_filenames,
 212             &codegened_func.symbol_name,
 213             "opt",
 214             module.isa(),
 215             &context.func,
 216             &clif_comments,
 217         );
 218
 219         if let Some(disasm) = &context.compiled_code().unwrap().disasm {
 220             crate::pretty_clif::write_ir_file(
 221                 &cx.output_filenames,
 222                 &format!("{}.vcode", codegened_func.symbol_name),
 223                 |file| file.write_all(disasm.as_bytes()),
 224             )
 225         }
 226     }
 227
 228     // Define debuginfo for function
 229     let isa = module.isa();
 230     let debug_context = &mut cx.debug_context;
 231     let unwind_context = &mut cx.unwind_context;
 232     cx.profiler.generic_activity("generate debug info").run(|| {
 233         if let Some(debug_context) = debug_context {
 234             codegened_func.func_debug_cx.unwrap().finalize(
 235                 debug_context,
 236                 codegened_func.func_id,
 237                 context,
 238             );
 239         }
 240         unwind_context.add_function(codegened_func.func_id, &context, isa);
 241     });
 242 }
 243
 244 pub(crate) fn verify_func(
 245     tcx: TyCtxt<'_>,
 246     writer: &crate::pretty_clif::CommentWriter,
 247     func: &Function,
 248 ) {
 249     tcx.prof.generic_activity("verify clif ir").run(|| {
 250         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 251         match cranelift_codegen::verify_function(&func, &flags) {
 252             Ok(_) => {}
 253             Err(err) => {
 254                 tcx.sess.err(&format!("{:?}", err));
 255                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 256                     &func,
 257                     Some(Box::new(writer)),
 258                     err,
 259                 );
 260                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 261             }
 262         }
 263     });
 264 }
 265
 266 fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
 267     if !crate::constant::check_constants(fx) {
 268         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
 269         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
 270         // compilation should have been aborted
 271         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 272         return;
 273     }
 274
 275     let arg_uninhabited = fx
 276         .mir
 277         .args_iter()
 278         .any(|arg| fx.layout_of(fx.monomorphize(fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
 279     if arg_uninhabited {
 280         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
 281         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
 282         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 283         return;
 284     }
 285     fx.tcx
 286         .prof
 287         .generic_activity("codegen prelude")
 288         .run(|| crate::abi::codegen_fn_prelude(fx, start_block));
 289
 290     for (bb, bb_data) in fx.mir.basic_blocks.iter_enumerated() {
 291         let block = fx.get_block(bb);
 292         fx.bcx.switch_to_block(block);
 293
 294         if bb_data.is_cleanup {
 295             // Unwinding after panicking is not supported
 296             continue;
 297
 298             // FIXME Once unwinding is supported and Cranelift supports marking blocks as cold, do
 299             // so for cleanup blocks.
 300         }
 301
 302         fx.bcx.ins().nop();
 303         for stmt in &bb_data.statements {
 304             fx.set_debug_loc(stmt.source_info);
 305             codegen_stmt(fx, block, stmt);
 306         }
 307
 308         if fx.clif_comments.enabled() {
 309             let mut terminator_head = "\n".to_string();
 310             with_no_trimmed_paths!({
 311                 bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 312             });
 313             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 314             fx.add_comment(inst, terminator_head);
 315         }
 316
 317         let source_info = bb_data.terminator().source_info;
 318         fx.set_debug_loc(source_info);
 319
 320         let _print_guard =
 321             crate::PrintOnPanic(|| format!("terminator {:?}", bb_data.terminator().kind));
 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                     let overflow_not_to_check = match msg {
 351                         AssertKind::OverflowNeg(..) => true,
 352                         AssertKind::Overflow(op, ..) => op.is_checkable(),
 353                         _ => false,
 354                     };
 355                     if overflow_not_to_check {
 356                         let target = fx.get_block(*target);
 357                         fx.bcx.ins().jump(target, &[]);
 358                         continue;
 359                     }
 360                 }
 361                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 362
 363                 let target = fx.get_block(*target);
 364                 let failure = fx.bcx.create_block();
 365                 fx.bcx.set_cold_block(failure);
 366
 367                 if *expected {
 368                     fx.bcx.ins().brz(cond, failure, &[]);
 369                 } else {
 370                     fx.bcx.ins().brnz(cond, failure, &[]);
 371                 };
 372                 fx.bcx.ins().jump(target, &[]);
 373
 374                 fx.bcx.switch_to_block(failure);
 375                 fx.bcx.ins().nop();
 376
 377                 match msg {
 378                     AssertKind::BoundsCheck { ref len, ref index } => {
 379                         let len = codegen_operand(fx, len).load_scalar(fx);
 380                         let index = codegen_operand(fx, index).load_scalar(fx);
 381                         let location = fx.get_caller_location(source_info).load_scalar(fx);
 382
 383                         codegen_panic_inner(
 384                             fx,
 385                             rustc_hir::LangItem::PanicBoundsCheck,
 386                             &[index, len, location],
 387                             source_info.span,
 388                         );
 389                     }
 390                     _ => {
 391                         let msg_str = msg.description();
 392                         codegen_panic(fx, msg_str, source_info);
 393                     }
 394                 }
 395             }
 396
 397             TerminatorKind::SwitchInt { discr, targets } => {
 398                 let discr = codegen_operand(fx, discr);
 399                 let switch_ty = discr.layout().ty;
 400                 let discr = discr.load_scalar(fx);
 401
 402                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 403                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 404                 if use_bool_opt {
 405                     assert_eq!(targets.iter().count(), 1);
 406                     let (then_value, then_block) = targets.iter().next().unwrap();
 407                     let then_block = fx.get_block(then_block);
 408                     let else_block = fx.get_block(targets.otherwise());
 409                     let test_zero = match then_value {
 410                         0 => true,
 411                         1 => false,
 412                         _ => unreachable!("{:?}", targets),
 413                     };
 414
 415                     let (discr, is_inverted) =
 416                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 417                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 418                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 419                         &fx.bcx, discr, test_zero,
 420                     ) {
 421                         if taken {
 422                             fx.bcx.ins().jump(then_block, &[]);
 423                         } else {
 424                             fx.bcx.ins().jump(else_block, &[]);
 425                         }
 426                     } else {
 427                         if test_zero {
 428                             fx.bcx.ins().brz(discr, then_block, &[]);
 429                             fx.bcx.ins().jump(else_block, &[]);
 430                         } else {
 431                             fx.bcx.ins().brnz(discr, then_block, &[]);
 432                             fx.bcx.ins().jump(else_block, &[]);
 433                         }
 434                     }
 435                 } else {
 436                     let mut switch = ::cranelift_frontend::Switch::new();
 437                     for (value, block) in targets.iter() {
 438                         let block = fx.get_block(block);
 439                         switch.set_entry(value, block);
 440                     }
 441                     let otherwise_block = fx.get_block(targets.otherwise());
 442                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 443                 }
 444             }
 445             TerminatorKind::Call {
 446                 func,
 447                 args,
 448                 destination,
 449                 target,
 450                 fn_span,
 451                 cleanup: _,
 452                 from_hir_call: _,
 453             } => {
 454                 fx.tcx.prof.generic_activity("codegen call").run(|| {
 455                     crate::abi::codegen_terminator_call(
 456                         fx,
 457                         mir::SourceInfo { span: *fn_span, ..source_info },
 458                         func,
 459                         args,
 460                         *destination,
 461                         *target,
 462                     )
 463                 });
 464             }
 465             TerminatorKind::InlineAsm {
 466                 template,
 467                 operands,
 468                 options,
 469                 destination,
 470                 line_spans: _,
 471                 cleanup: _,
 472             } => {
 473                 if options.contains(InlineAsmOptions::MAY_UNWIND) {
 474                     fx.tcx.sess.span_fatal(
 475                         source_info.span,
 476                         "cranelift doesn't support unwinding from inline assembly.",
 477                     );
 478                 }
 479
 480                 crate::inline_asm::codegen_inline_asm(
 481                     fx,
 482                     source_info.span,
 483                     template,
 484                     operands,
 485                     *options,
 486                     *destination,
 487                 );
 488             }
 489             TerminatorKind::Abort => {
 490                 codegen_panic_cannot_unwind(fx, source_info);
 491             }
 492             TerminatorKind::Resume => {
 493                 // FIXME implement unwinding
 494                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 495             }
 496             TerminatorKind::Unreachable => {
 497                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 498             }
 499             TerminatorKind::Yield { .. }
 500             | TerminatorKind::FalseEdge { .. }
 501             | TerminatorKind::FalseUnwind { .. }
 502             | TerminatorKind::DropAndReplace { .. }
 503             | TerminatorKind::GeneratorDrop => {
 504                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 505             }
 506             TerminatorKind::Drop { place, target, unwind: _ } => {
 507                 let drop_place = codegen_place(fx, *place);
 508                 crate::abi::codegen_drop(fx, source_info, drop_place);
 509
 510                 let target_block = fx.get_block(*target);
 511                 fx.bcx.ins().jump(target_block, &[]);
 512             }
 513         };
 514     }
 515 }
 516
 517 fn codegen_stmt<'tcx>(
 518     fx: &mut FunctionCx<'_, '_, 'tcx>,
 519     #[allow(unused_variables)] cur_block: Block,
 520     stmt: &Statement<'tcx>,
 521 ) {
 522     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 523
 524     fx.set_debug_loc(stmt.source_info);
 525
 526     #[cfg(any())] // This is never true
 527     match &stmt.kind {
 528         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 529         _ => {
 530             if fx.clif_comments.enabled() {
 531                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 532                 fx.add_comment(inst, format!("{:?}", stmt));
 533             }
 534         }
 535     }
 536
 537     match &stmt.kind {
 538         StatementKind::SetDiscriminant { place, variant_index } => {
 539             let place = codegen_place(fx, **place);
 540             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 541         }
 542         StatementKind::Assign(to_place_and_rval) => {
 543             let lval = codegen_place(fx, to_place_and_rval.0);
 544             let dest_layout = lval.layout();
 545             match to_place_and_rval.1 {
 546                 Rvalue::Use(ref operand) => {
 547                     let val = codegen_operand(fx, operand);
 548                     lval.write_cvalue(fx, val);
 549                 }
 550                 Rvalue::CopyForDeref(place) => {
 551                     let cplace = codegen_place(fx, place);
 552                     let val = cplace.to_cvalue(fx);
 553                     lval.write_cvalue(fx, val)
 554                 }
 555                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 556                     let place = codegen_place(fx, place);
 557                     let ref_ = place.place_ref(fx, lval.layout());
 558                     lval.write_cvalue(fx, ref_);
 559                 }
 560                 Rvalue::ThreadLocalRef(def_id) => {
 561                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 562                     lval.write_cvalue(fx, val);
 563                 }
 564                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 565                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 566                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 567
 568                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 569                     lval.write_cvalue(fx, res);
 570                 }
 571                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 572                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 573                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 574
 575                     let res = crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs);
 576                     lval.write_cvalue(fx, res);
 577                 }
 578                 Rvalue::UnaryOp(un_op, ref operand) => {
 579                     let operand = codegen_operand(fx, operand);
 580                     let layout = operand.layout();
 581                     let val = operand.load_scalar(fx);
 582                     let res = match un_op {
 583                         UnOp::Not => match layout.ty.kind() {
 584                             ty::Bool => {
 585                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 586                                 CValue::by_val(res, layout)
 587                             }
 588                             ty::Uint(_) | ty::Int(_) => {
 589                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 590                             }
 591                             _ => unreachable!("un op Not for {:?}", layout.ty),
 592                         },
 593                         UnOp::Neg => match layout.ty.kind() {
 594                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 595                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 596                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 597                         },
 598                     };
 599                     lval.write_cvalue(fx, res);
 600                 }
 601                 Rvalue::Cast(
 602                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 603                     ref operand,
 604                     to_ty,
 605                 ) => {
 606                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 607                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 608                     match *from_ty.kind() {
 609                         ty::FnDef(def_id, substs) => {
 610                             let func_ref = fx.get_function_ref(
 611                                 Instance::resolve_for_fn_ptr(
 612                                     fx.tcx,
 613                                     ParamEnv::reveal_all(),
 614                                     def_id,
 615                                     substs,
 616                                 )
 617                                 .unwrap()
 618                                 .polymorphize(fx.tcx),
 619                             );
 620                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 621                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 622                         }
 623                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 624                     }
 625                 }
 626                 Rvalue::Cast(
 627                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 628                     ref operand,
 629                     to_ty,
 630                 )
 631                 | Rvalue::Cast(
 632                     CastKind::Pointer(PointerCast::MutToConstPointer),
 633                     ref operand,
 634                     to_ty,
 635                 )
 636                 | Rvalue::Cast(
 637                     CastKind::Pointer(PointerCast::ArrayToPointer),
 638                     ref operand,
 639                     to_ty,
 640                 ) => {
 641                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 642                     let operand = codegen_operand(fx, operand);
 643                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 644                 }
 645                 Rvalue::Cast(
 646                     CastKind::IntToInt
 647                     | CastKind::FloatToFloat
 648                     | CastKind::FloatToInt
 649                     | CastKind::IntToFloat
 650                     | CastKind::FnPtrToPtr
 651                     | CastKind::PtrToPtr
 652                     | CastKind::PointerExposeAddress
 653                     | CastKind::PointerFromExposedAddress,
 654                     ref operand,
 655                     to_ty,
 656                 ) => {
 657                     let operand = codegen_operand(fx, operand);
 658                     let from_ty = operand.layout().ty;
 659                     let to_ty = fx.monomorphize(to_ty);
 660
 661                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 662                         ty.builtin_deref(true)
 663                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 664                                 has_ptr_meta(fx.tcx, pointee_ty)
 665                             })
 666                             .unwrap_or(false)
 667                     }
 668
 669                     if is_fat_ptr(fx, from_ty) {
 670                         if is_fat_ptr(fx, to_ty) {
 671                             // fat-ptr -> fat-ptr
 672                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 673                         } else {
 674                             // fat-ptr -> thin-ptr
 675                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 676                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 677                         }
 678                     } else {
 679                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 680                         let from = operand.load_scalar(fx);
 681
 682                         let res = clif_int_or_float_cast(
 683                             fx,
 684                             from,
 685                             type_sign(from_ty),
 686                             to_clif_ty,
 687                             type_sign(to_ty),
 688                         );
 689                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 690                     }
 691                 }
 692                 Rvalue::Cast(
 693                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 694                     ref operand,
 695                     _to_ty,
 696                 ) => {
 697                     let operand = codegen_operand(fx, operand);
 698                     match *operand.layout().ty.kind() {
 699                         ty::Closure(def_id, substs) => {
 700                             let instance = Instance::resolve_closure(
 701                                 fx.tcx,
 702                                 def_id,
 703                                 substs,
 704                                 ty::ClosureKind::FnOnce,
 705                             )
 706                             .expect("failed to normalize and resolve closure during codegen")
 707                             .polymorphize(fx.tcx);
 708                             let func_ref = fx.get_function_ref(instance);
 709                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 710                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 711                         }
 712                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 713                     }
 714                 }
 715                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 716                     let operand = codegen_operand(fx, operand);
 717                     operand.unsize_value(fx, lval);
 718                 }
 719                 Rvalue::Cast(CastKind::DynStar, ref operand, _) => {
 720                     let operand = codegen_operand(fx, operand);
 721                     operand.coerce_dyn_star(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!(lval.layout().ty.is_sized(fx.tcx, ParamEnv::reveal_all()));
 782                     let layout = fx.layout_of(fx.monomorphize(ty));
 783                     let val = match null_op {
 784                         NullOp::SizeOf => layout.size.bytes(),
 785                         NullOp::AlignOf => layout.align.abi.bytes(),
 786                     };
 787                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), val.into());
 788                     lval.write_cvalue(fx, val);
 789                 }
 790                 Rvalue::Aggregate(ref kind, ref operands) => {
 791                     let (variant_index, variant_dest, active_field_index) = match **kind {
 792                         mir::AggregateKind::Adt(_, variant_index, _, _, active_field_index) => {
 793                             let variant_dest = lval.downcast_variant(fx, variant_index);
 794                             (variant_index, variant_dest, active_field_index)
 795                         }
 796                         _ => (VariantIdx::from_u32(0), lval, None),
 797                     };
 798                     if active_field_index.is_some() {
 799                         assert_eq!(operands.len(), 1);
 800                     }
 801                     for (i, operand) in operands.iter().enumerate() {
 802                         let operand = codegen_operand(fx, operand);
 803                         let field_index = active_field_index.unwrap_or(i);
 804                         let to = if let mir::AggregateKind::Array(_) = **kind {
 805                             let index = fx.bcx.ins().iconst(fx.pointer_type, field_index as i64);
 806                             variant_dest.place_index(fx, index)
 807                         } else {
 808                             variant_dest.place_field(fx, mir::Field::new(field_index))
 809                         };
 810                         to.write_cvalue(fx, operand);
 811                     }
 812                     crate::discriminant::codegen_set_discriminant(fx, lval, variant_index);
 813                 }
 814             }
 815         }
 816         StatementKind::StorageLive(_)
 817         | StatementKind::StorageDead(_)
 818         | StatementKind::Deinit(_)
 819         | StatementKind::ConstEvalCounter
 820         | StatementKind::Nop
 821         | StatementKind::FakeRead(..)
 822         | StatementKind::Retag { .. }
 823         | StatementKind::AscribeUserType(..) => {}
 824
 825         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 826         StatementKind::Intrinsic(ref intrinsic) => match &**intrinsic {
 827             // We ignore `assume` intrinsics, they are only useful for optimizations
 828             NonDivergingIntrinsic::Assume(_) => {}
 829             NonDivergingIntrinsic::CopyNonOverlapping(mir::CopyNonOverlapping {
 830                 src,
 831                 dst,
 832                 count,
 833             }) => {
 834                 let dst = codegen_operand(fx, dst);
 835                 let pointee = dst
 836                     .layout()
 837                     .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 838                     .expect("Expected pointer");
 839                 let dst = dst.load_scalar(fx);
 840                 let src = codegen_operand(fx, src).load_scalar(fx);
 841                 let count = codegen_operand(fx, count).load_scalar(fx);
 842                 let elem_size: u64 = pointee.size.bytes();
 843                 let bytes = if elem_size != 1 {
 844                     fx.bcx.ins().imul_imm(count, elem_size as i64)
 845                 } else {
 846                     count
 847                 };
 848                 fx.bcx.call_memcpy(fx.target_config, dst, src, bytes);
 849             }
 850         },
 851     }
 852 }
 853
 854 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 855     match *place.layout().ty.kind() {
 856         ty::Array(_elem_ty, len) => {
 857             let len = fx.monomorphize(len).eval_target_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 858             fx.bcx.ins().iconst(fx.pointer_type, len)
 859         }
 860         ty::Slice(_elem_ty) => {
 861             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 862         }
 863         _ => bug!("Rvalue::Len({:?})", place),
 864     }
 865 }
 866
 867 pub(crate) fn codegen_place<'tcx>(
 868     fx: &mut FunctionCx<'_, '_, 'tcx>,
 869     place: Place<'tcx>,
 870 ) -> CPlace<'tcx> {
 871     let mut cplace = fx.get_local_place(place.local);
 872
 873     for elem in place.projection {
 874         match elem {
 875             PlaceElem::Deref => {
 876                 cplace = cplace.place_deref(fx);
 877             }
 878             PlaceElem::OpaqueCast(ty) => cplace = cplace.place_opaque_cast(fx, ty),
 879             PlaceElem::Field(field, _ty) => {
 880                 cplace = cplace.place_field(fx, field);
 881             }
 882             PlaceElem::Index(local) => {
 883                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 884                 cplace = cplace.place_index(fx, index);
 885             }
 886             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 887                 let offset: u64 = offset;
 888                 let index = if !from_end {
 889                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 890                 } else {
 891                     let len = codegen_array_len(fx, cplace);
 892                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 893                 };
 894                 cplace = cplace.place_index(fx, index);
 895             }
 896             PlaceElem::Subslice { from, to, from_end } => {
 897                 // These indices are generated by slice patterns.
 898                 // slice[from:-to] in Python terms.
 899
 900                 let from: u64 = from;
 901                 let to: u64 = to;
 902
 903                 match cplace.layout().ty.kind() {
 904                     ty::Array(elem_ty, _len) => {
 905                         assert!(!from_end, "array subslices are never `from_end`");
 906                         let elem_layout = fx.layout_of(*elem_ty);
 907                         let ptr = cplace.to_ptr();
 908                         cplace = CPlace::for_ptr(
 909                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 910                             fx.layout_of(fx.tcx.mk_array(*elem_ty, to - from)),
 911                         );
 912                     }
 913                     ty::Slice(elem_ty) => {
 914                         assert!(from_end, "slice subslices should be `from_end`");
 915                         let elem_layout = fx.layout_of(*elem_ty);
 916                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 917                         let len = len.unwrap();
 918                         cplace = CPlace::for_ptr_with_extra(
 919                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 920                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 921                             cplace.layout(),
 922                         );
 923                     }
 924                     _ => unreachable!(),
 925                 }
 926             }
 927             PlaceElem::Downcast(_adt_def, variant) => {
 928                 cplace = cplace.downcast_variant(fx, variant);
 929             }
 930         }
 931     }
 932
 933     cplace
 934 }
 935
 936 pub(crate) fn codegen_operand<'tcx>(
 937     fx: &mut FunctionCx<'_, '_, 'tcx>,
 938     operand: &Operand<'tcx>,
 939 ) -> CValue<'tcx> {
 940     match operand {
 941         Operand::Move(place) | Operand::Copy(place) => {
 942             let cplace = codegen_place(fx, *place);
 943             cplace.to_cvalue(fx)
 944         }
 945         Operand::Constant(const_) => crate::constant::codegen_constant_operand(fx, const_),
 946     }
 947 }
 948
 949 pub(crate) fn codegen_panic<'tcx>(
 950     fx: &mut FunctionCx<'_, '_, 'tcx>,
 951     msg_str: &str,
 952     source_info: mir::SourceInfo,
 953 ) {
 954     let location = fx.get_caller_location(source_info).load_scalar(fx);
 955
 956     let msg_ptr = fx.anonymous_str(msg_str);
 957     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 958     let args = [msg_ptr, msg_len, location];
 959
 960     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
 961 }
 962
 963 pub(crate) fn codegen_panic_nounwind<'tcx>(
 964     fx: &mut FunctionCx<'_, '_, 'tcx>,
 965     msg_str: &str,
 966     source_info: mir::SourceInfo,
 967 ) {
 968     let msg_ptr = fx.anonymous_str(msg_str);
 969     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 970     let args = [msg_ptr, msg_len];
 971
 972     codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, source_info.span);
 973 }
 974
 975 pub(crate) fn codegen_panic_cannot_unwind<'tcx>(
 976     fx: &mut FunctionCx<'_, '_, 'tcx>,
 977     source_info: mir::SourceInfo,
 978 ) {
 979     let args = [];
 980
 981     codegen_panic_inner(fx, rustc_hir::LangItem::PanicCannotUnwind, &args, source_info.span);
 982 }
 983
 984 fn codegen_panic_inner<'tcx>(
 985     fx: &mut FunctionCx<'_, '_, 'tcx>,
 986     lang_item: rustc_hir::LangItem,
 987     args: &[Value],
 988     span: Span,
 989 ) {
 990     let def_id = fx
 991         .tcx
 992         .lang_items()
 993         .require(lang_item)
 994         .unwrap_or_else(|e| fx.tcx.sess.span_fatal(span, e.to_string()));
 995
 996     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 997     let symbol_name = fx.tcx.symbol_name(instance).name;
 998
 999     fx.lib_call(
1000         &*symbol_name,
1001         args.iter().map(|&arg| AbiParam::new(fx.bcx.func.dfg.value_type(arg))).collect(),
1002         vec![],
1003         args,
1004     );
1005
1006     fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
1007 }