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