src/base.rs

   1 //! Codegen of a single function
   2
   3 use rustc_ast::InlineAsmOptions;
   4 use rustc_index::vec::IndexVec;
   5 use rustc_middle::ty::adjustment::PointerCast;
   6 use rustc_middle::ty::layout::FnAbiOf;
   7 use rustc_middle::ty::print::with_no_trimmed_paths;
   8
   9 use indexmap::IndexSet;
  10
  11 use crate::constant::ConstantCx;
  12 use crate::prelude::*;
  13 use crate::pretty_clif::CommentWriter;
  14
  15 pub(crate) fn codegen_fn<'tcx>(
  16     cx: &mut crate::CodegenCx<'tcx>,
  17     module: &mut dyn Module,
  18     instance: Instance<'tcx>,
  19 ) {
  20     let tcx = cx.tcx;
  21
  22     let _inst_guard =
  23         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  24     debug_assert!(!instance.substs.needs_infer());
  25
  26     let mir = tcx.instance_mir(instance.def);
  27     let _mir_guard = crate::PrintOnPanic(|| {
  28         let mut buf = Vec::new();
  29         with_no_trimmed_paths!({
  30             rustc_middle::mir::pretty::write_mir_fn(tcx, mir, &mut |_, _| Ok(()), &mut buf)
  31                 .unwrap();
  32         });
  33         String::from_utf8_lossy(&buf).into_owned()
  34     });
  35
  36     // Declare function
  37     let symbol_name = tcx.symbol_name(instance);
  38     let sig = get_function_sig(tcx, module.isa().triple(), instance);
  39     let func_id = module.declare_function(symbol_name.name, Linkage::Local, &sig).unwrap();
  40
  41     cx.cached_context.clear();
  42
  43     // Make the FunctionBuilder
  44     let mut func_ctx = FunctionBuilderContext::new();
  45     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  46     func.name = ExternalName::user(0, func_id.as_u32());
  47     func.signature = sig;
  48     func.collect_debug_info();
  49
  50     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  51
  52     // Predefine blocks
  53     let start_block = bcx.create_block();
  54     let block_map: IndexVec<BasicBlock, Block> =
  55         (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  56
  57     // Make FunctionCx
  58     let target_config = module.target_config();
  59     let pointer_type = target_config.pointer_type();
  60     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  61
  62     let mut fx = FunctionCx {
  63         cx,
  64         module,
  65         tcx,
  66         target_config,
  67         pointer_type,
  68         constants_cx: ConstantCx::new(),
  69
  70         instance,
  71         symbol_name,
  72         mir,
  73         fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())),
  74
  75         bcx,
  76         block_map,
  77         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  78         caller_location: None, // set by `codegen_fn_prelude`
  79
  80         clif_comments,
  81         source_info_set: indexmap::IndexSet::new(),
  82         next_ssa_var: 0,
  83     };
  84
  85     let arg_uninhabited = fx
  86         .mir
  87         .args_iter()
  88         .any(|arg| fx.layout_of(fx.monomorphize(fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  89
  90     if !crate::constant::check_constants(&mut fx) {
  91         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  92         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  93         crate::trap::trap_unreachable(&mut fx, "compilation should have been aborted");
  94     } else if arg_uninhabited {
  95         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  96         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  97         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
  98     } else {
  99         tcx.sess.time("codegen clif ir", || {
 100             tcx.sess
 101                 .time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
 102             codegen_fn_content(&mut fx);
 103         });
 104     }
 105
 106     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 107     let instance = fx.instance;
 108     let clif_comments = fx.clif_comments;
 109     let source_info_set = fx.source_info_set;
 110     let local_map = fx.local_map;
 111
 112     fx.constants_cx.finalize(fx.tcx, &mut *fx.module);
 113
 114     crate::pretty_clif::write_clif_file(
 115         tcx,
 116         "unopt",
 117         module.isa(),
 118         instance,
 119         &func,
 120         &clif_comments,
 121     );
 122
 123     // Verify function
 124     verify_func(tcx, &clif_comments, &func);
 125
 126     compile_fn(
 127         cx,
 128         module,
 129         instance,
 130         symbol_name.name,
 131         func_id,
 132         func,
 133         clif_comments,
 134         source_info_set,
 135         local_map,
 136     );
 137 }
 138
 139 fn compile_fn<'tcx>(
 140     cx: &mut crate::CodegenCx<'tcx>,
 141     module: &mut dyn Module,
 142     instance: Instance<'tcx>,
 143     symbol_name: &str,
 144     func_id: FuncId,
 145     func: Function,
 146     mut clif_comments: CommentWriter,
 147     source_info_set: IndexSet<SourceInfo>,
 148     local_map: IndexVec<mir::Local, CPlace<'tcx>>,
 149 ) {
 150     let tcx = cx.tcx;
 151
 152     // Store function in context
 153     let context = &mut cx.cached_context;
 154     context.clear();
 155     context.func = func;
 156
 157     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 158     // instruction, which doesn't have an encoding.
 159     context.compute_cfg();
 160     context.compute_domtree();
 161     context.eliminate_unreachable_code(module.isa()).unwrap();
 162     context.dce(module.isa()).unwrap();
 163     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 164     // invalidate it when it would change.
 165     context.domtree.clear();
 166
 167     // Perform rust specific optimizations
 168     tcx.sess.time("optimize clif ir", || {
 169         crate::optimize::optimize_function(
 170             tcx,
 171             module.isa(),
 172             instance,
 173             context,
 174             &mut clif_comments,
 175         );
 176     });
 177
 178     #[cfg(any())] // This is never true
 179     let _clif_guard = {
 180         use std::fmt::Write;
 181
 182         let func_clone = context.func.clone();
 183         let clif_comments_clone = clif_comments.clone();
 184         let mut clif = String::new();
 185         for flag in module.isa().flags().iter() {
 186             writeln!(clif, "set {}", flag).unwrap();
 187         }
 188         write!(clif, "target {}", module.isa().triple().architecture.to_string()).unwrap();
 189         for isa_flag in module.isa().isa_flags().iter() {
 190             write!(clif, " {}", isa_flag).unwrap();
 191         }
 192         writeln!(clif, "\n").unwrap();
 193         crate::PrintOnPanic(move || {
 194             let mut clif = clif.clone();
 195             ::cranelift_codegen::write::decorate_function(
 196                 &mut &clif_comments_clone,
 197                 &mut clif,
 198                 &func_clone,
 199             )
 200             .unwrap();
 201             clif
 202         })
 203     };
 204
 205     // Define function
 206     tcx.sess.time("define function", || {
 207         context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 208         module.define_function(func_id, context).unwrap();
 209     });
 210
 211     // Write optimized function to file for debugging
 212     crate::pretty_clif::write_clif_file(
 213         tcx,
 214         "opt",
 215         module.isa(),
 216         instance,
 217         &context.func,
 218         &clif_comments,
 219     );
 220
 221     if let Some(disasm) = &context.mach_compile_result.as_ref().unwrap().disasm {
 222         crate::pretty_clif::write_ir_file(
 223             tcx,
 224             || format!("{}.vcode", tcx.symbol_name(instance).name),
 225             |file| file.write_all(disasm.as_bytes()),
 226         )
 227     }
 228
 229     // Define debuginfo for function
 230     let isa = module.isa();
 231     let debug_context = &mut cx.debug_context;
 232     let unwind_context = &mut cx.unwind_context;
 233     tcx.sess.time("generate debug info", || {
 234         if let Some(debug_context) = debug_context {
 235             debug_context.define_function(
 236                 instance,
 237                 func_id,
 238                 symbol_name,
 239                 isa,
 240                 context,
 241                 &source_info_set,
 242                 local_map,
 243             );
 244         }
 245         unwind_context.add_function(func_id, &context, isa);
 246     });
 247 }
 248
 249 pub(crate) fn verify_func(
 250     tcx: TyCtxt<'_>,
 251     writer: &crate::pretty_clif::CommentWriter,
 252     func: &Function,
 253 ) {
 254     tcx.sess.time("verify clif ir", || {
 255         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 256         match cranelift_codegen::verify_function(&func, &flags) {
 257             Ok(_) => {}
 258             Err(err) => {
 259                 tcx.sess.err(&format!("{:?}", err));
 260                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 261                     &func,
 262                     Some(Box::new(writer)),
 263                     err,
 264                 );
 265                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 266             }
 267         }
 268     });
 269 }
 270
 271 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, '_>) {
 272     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 273         let block = fx.get_block(bb);
 274         fx.bcx.switch_to_block(block);
 275
 276         if bb_data.is_cleanup {
 277             // Unwinding after panicking is not supported
 278             continue;
 279
 280             // FIXME Once unwinding is supported and Cranelift supports marking blocks as cold, do
 281             // so for cleanup blocks.
 282         }
 283
 284         fx.bcx.ins().nop();
 285         for stmt in &bb_data.statements {
 286             fx.set_debug_loc(stmt.source_info);
 287             codegen_stmt(fx, block, stmt);
 288         }
 289
 290         if fx.clif_comments.enabled() {
 291             let mut terminator_head = "\n".to_string();
 292             with_no_trimmed_paths!({
 293                 bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 294             });
 295             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 296             fx.add_comment(inst, terminator_head);
 297         }
 298
 299         let source_info = bb_data.terminator().source_info;
 300         fx.set_debug_loc(source_info);
 301
 302         match &bb_data.terminator().kind {
 303             TerminatorKind::Goto { target } => {
 304                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 305                     let mut can_immediately_return = true;
 306                     for stmt in &fx.mir[*target].statements {
 307                         if let StatementKind::StorageDead(_) = stmt.kind {
 308                         } else {
 309                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 310                             can_immediately_return = false;
 311                             break;
 312                         }
 313                     }
 314
 315                     if can_immediately_return {
 316                         crate::abi::codegen_return(fx);
 317                         continue;
 318                     }
 319                 }
 320
 321                 let block = fx.get_block(*target);
 322                 fx.bcx.ins().jump(block, &[]);
 323             }
 324             TerminatorKind::Return => {
 325                 crate::abi::codegen_return(fx);
 326             }
 327             TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
 328                 if !fx.tcx.sess.overflow_checks() {
 329                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 330                         let target = fx.get_block(*target);
 331                         fx.bcx.ins().jump(target, &[]);
 332                         continue;
 333                     }
 334                 }
 335                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 336
 337                 let target = fx.get_block(*target);
 338                 let failure = fx.bcx.create_block();
 339                 fx.bcx.set_cold_block(failure);
 340
 341                 if *expected {
 342                     fx.bcx.ins().brz(cond, failure, &[]);
 343                 } else {
 344                     fx.bcx.ins().brnz(cond, failure, &[]);
 345                 };
 346                 fx.bcx.ins().jump(target, &[]);
 347
 348                 fx.bcx.switch_to_block(failure);
 349                 fx.bcx.ins().nop();
 350
 351                 match msg {
 352                     AssertKind::BoundsCheck { ref len, ref index } => {
 353                         let len = codegen_operand(fx, len).load_scalar(fx);
 354                         let index = codegen_operand(fx, index).load_scalar(fx);
 355                         let location = fx.get_caller_location(source_info).load_scalar(fx);
 356
 357                         codegen_panic_inner(
 358                             fx,
 359                             rustc_hir::LangItem::PanicBoundsCheck,
 360                             &[index, len, location],
 361                             source_info.span,
 362                         );
 363                     }
 364                     _ => {
 365                         let msg_str = msg.description();
 366                         codegen_panic(fx, msg_str, source_info);
 367                     }
 368                 }
 369             }
 370
 371             TerminatorKind::SwitchInt { discr, switch_ty, targets } => {
 372                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 373
 374                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 375                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 376                 if use_bool_opt {
 377                     assert_eq!(targets.iter().count(), 1);
 378                     let (then_value, then_block) = targets.iter().next().unwrap();
 379                     let then_block = fx.get_block(then_block);
 380                     let else_block = fx.get_block(targets.otherwise());
 381                     let test_zero = match then_value {
 382                         0 => true,
 383                         1 => false,
 384                         _ => unreachable!("{:?}", targets),
 385                     };
 386
 387                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 388                     let (discr, is_inverted) =
 389                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 390                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 391                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 392                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 393                         &fx.bcx, discr, test_zero,
 394                     ) {
 395                         if taken {
 396                             fx.bcx.ins().jump(then_block, &[]);
 397                         } else {
 398                             fx.bcx.ins().jump(else_block, &[]);
 399                         }
 400                     } else {
 401                         if test_zero {
 402                             fx.bcx.ins().brz(discr, then_block, &[]);
 403                             fx.bcx.ins().jump(else_block, &[]);
 404                         } else {
 405                             fx.bcx.ins().brnz(discr, then_block, &[]);
 406                             fx.bcx.ins().jump(else_block, &[]);
 407                         }
 408                     }
 409                 } else {
 410                     let mut switch = ::cranelift_frontend::Switch::new();
 411                     for (value, block) in targets.iter() {
 412                         let block = fx.get_block(block);
 413                         switch.set_entry(value, block);
 414                     }
 415                     let otherwise_block = fx.get_block(targets.otherwise());
 416                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 417                 }
 418             }
 419             TerminatorKind::Call {
 420                 func,
 421                 args,
 422                 destination,
 423                 target,
 424                 fn_span,
 425                 cleanup: _,
 426                 from_hir_call: _,
 427             } => {
 428                 fx.tcx.sess.time("codegen call", || {
 429                     crate::abi::codegen_terminator_call(
 430                         fx,
 431                         mir::SourceInfo { span: *fn_span, ..source_info },
 432                         func,
 433                         args,
 434                         *destination,
 435                         *target,
 436                     )
 437                 });
 438             }
 439             TerminatorKind::InlineAsm {
 440                 template,
 441                 operands,
 442                 options,
 443                 destination,
 444                 line_spans: _,
 445                 cleanup: _,
 446             } => {
 447                 if options.contains(InlineAsmOptions::MAY_UNWIND) {
 448                     fx.tcx.sess.span_fatal(
 449                         source_info.span,
 450                         "cranelift doesn't support unwinding from inline assembly.",
 451                     );
 452                 }
 453
 454                 crate::inline_asm::codegen_inline_asm(
 455                     fx,
 456                     source_info.span,
 457                     template,
 458                     operands,
 459                     *options,
 460                 );
 461
 462                 match *destination {
 463                     Some(destination) => {
 464                         let destination_block = fx.get_block(destination);
 465                         fx.bcx.ins().jump(destination_block, &[]);
 466                     }
 467                     None => {
 468                         fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 469                     }
 470                 }
 471             }
 472             TerminatorKind::Resume | TerminatorKind::Abort => {
 473                 // FIXME implement unwinding
 474                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 475             }
 476             TerminatorKind::Unreachable => {
 477                 fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 478             }
 479             TerminatorKind::Yield { .. }
 480             | TerminatorKind::FalseEdge { .. }
 481             | TerminatorKind::FalseUnwind { .. }
 482             | TerminatorKind::DropAndReplace { .. }
 483             | TerminatorKind::GeneratorDrop => {
 484                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 485             }
 486             TerminatorKind::Drop { place, target, unwind: _ } => {
 487                 let drop_place = codegen_place(fx, *place);
 488                 crate::abi::codegen_drop(fx, source_info, drop_place);
 489
 490                 let target_block = fx.get_block(*target);
 491                 fx.bcx.ins().jump(target_block, &[]);
 492             }
 493         };
 494     }
 495
 496     fx.bcx.seal_all_blocks();
 497     fx.bcx.finalize();
 498 }
 499
 500 fn codegen_stmt<'tcx>(
 501     fx: &mut FunctionCx<'_, '_, 'tcx>,
 502     #[allow(unused_variables)] cur_block: Block,
 503     stmt: &Statement<'tcx>,
 504 ) {
 505     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 506
 507     fx.set_debug_loc(stmt.source_info);
 508
 509     #[cfg(any())] // This is never true
 510     match &stmt.kind {
 511         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 512         _ => {
 513             if fx.clif_comments.enabled() {
 514                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 515                 fx.add_comment(inst, format!("{:?}", stmt));
 516             }
 517         }
 518     }
 519
 520     match &stmt.kind {
 521         StatementKind::SetDiscriminant { place, variant_index } => {
 522             let place = codegen_place(fx, **place);
 523             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 524         }
 525         StatementKind::Assign(to_place_and_rval) => {
 526             let lval = codegen_place(fx, to_place_and_rval.0);
 527             let dest_layout = lval.layout();
 528             match to_place_and_rval.1 {
 529                 Rvalue::Use(ref operand) => {
 530                     let val = codegen_operand(fx, operand);
 531                     lval.write_cvalue(fx, val);
 532                 }
 533                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 534                     let place = codegen_place(fx, place);
 535                     let ref_ = place.place_ref(fx, lval.layout());
 536                     lval.write_cvalue(fx, ref_);
 537                 }
 538                 Rvalue::ThreadLocalRef(def_id) => {
 539                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 540                     lval.write_cvalue(fx, val);
 541                 }
 542                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 543                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 544                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 545
 546                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 547                     lval.write_cvalue(fx, res);
 548                 }
 549                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 550                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 551                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 552
 553                     let res = if !fx.tcx.sess.overflow_checks() {
 554                         let val =
 555                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 556                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 557                         CValue::by_val_pair(val, is_overflow, lval.layout())
 558                     } else {
 559                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 560                     };
 561
 562                     lval.write_cvalue(fx, res);
 563                 }
 564                 Rvalue::UnaryOp(un_op, ref operand) => {
 565                     let operand = codegen_operand(fx, operand);
 566                     let layout = operand.layout();
 567                     let val = operand.load_scalar(fx);
 568                     let res = match un_op {
 569                         UnOp::Not => match layout.ty.kind() {
 570                             ty::Bool => {
 571                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 572                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 573                             }
 574                             ty::Uint(_) | ty::Int(_) => {
 575                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 576                             }
 577                             _ => unreachable!("un op Not for {:?}", layout.ty),
 578                         },
 579                         UnOp::Neg => match layout.ty.kind() {
 580                             ty::Int(IntTy::I128) => {
 581                                 // FIXME remove this case once ineg.i128 works
 582                                 let zero =
 583                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 584                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 585                             }
 586                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 587                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 588                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 589                         },
 590                     };
 591                     lval.write_cvalue(fx, res);
 592                 }
 593                 Rvalue::Cast(
 594                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 595                     ref operand,
 596                     to_ty,
 597                 ) => {
 598                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 599                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 600                     match *from_ty.kind() {
 601                         ty::FnDef(def_id, substs) => {
 602                             let func_ref = fx.get_function_ref(
 603                                 Instance::resolve_for_fn_ptr(
 604                                     fx.tcx,
 605                                     ParamEnv::reveal_all(),
 606                                     def_id,
 607                                     substs,
 608                                 )
 609                                 .unwrap()
 610                                 .polymorphize(fx.tcx),
 611                             );
 612                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 613                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 614                         }
 615                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 616                     }
 617                 }
 618                 Rvalue::Cast(
 619                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 620                     ref operand,
 621                     to_ty,
 622                 )
 623                 | Rvalue::Cast(
 624                     CastKind::Pointer(PointerCast::MutToConstPointer),
 625                     ref operand,
 626                     to_ty,
 627                 )
 628                 | Rvalue::Cast(
 629                     CastKind::Pointer(PointerCast::ArrayToPointer),
 630                     ref operand,
 631                     to_ty,
 632                 ) => {
 633                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 634                     let operand = codegen_operand(fx, operand);
 635                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 636                 }
 637                 Rvalue::Cast(
 638                     CastKind::Misc
 639                     | CastKind::PointerExposeAddress
 640                     | CastKind::PointerFromExposedAddress,
 641                     ref operand,
 642                     to_ty,
 643                 ) => {
 644                     let operand = codegen_operand(fx, operand);
 645                     let from_ty = operand.layout().ty;
 646                     let to_ty = fx.monomorphize(to_ty);
 647
 648                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 649                         ty.builtin_deref(true)
 650                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 651                                 has_ptr_meta(fx.tcx, pointee_ty)
 652                             })
 653                             .unwrap_or(false)
 654                     }
 655
 656                     if is_fat_ptr(fx, from_ty) {
 657                         if is_fat_ptr(fx, to_ty) {
 658                             // fat-ptr -> fat-ptr
 659                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 660                         } else {
 661                             // fat-ptr -> thin-ptr
 662                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 663                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 664                         }
 665                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 666                         // enum -> discriminant value
 667                         assert!(adt_def.is_enum());
 668                         match to_ty.kind() {
 669                             ty::Uint(_) | ty::Int(_) => {}
 670                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 671                         }
 672                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 673
 674                         let discriminant = crate::discriminant::codegen_get_discriminant(
 675                             fx,
 676                             operand,
 677                             fx.layout_of(operand.layout().ty.discriminant_ty(fx.tcx)),
 678                         )
 679                         .load_scalar(fx);
 680
 681                         let res = crate::cast::clif_intcast(
 682                             fx,
 683                             discriminant,
 684                             to_clif_ty,
 685                             to_ty.is_signed(),
 686                         );
 687                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 688                     } else {
 689                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 690                         let from = operand.load_scalar(fx);
 691
 692                         let res = clif_int_or_float_cast(
 693                             fx,
 694                             from,
 695                             type_sign(from_ty),
 696                             to_clif_ty,
 697                             type_sign(to_ty),
 698                         );
 699                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 700                     }
 701                 }
 702                 Rvalue::Cast(
 703                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 704                     ref operand,
 705                     _to_ty,
 706                 ) => {
 707                     let operand = codegen_operand(fx, operand);
 708                     match *operand.layout().ty.kind() {
 709                         ty::Closure(def_id, substs) => {
 710                             let instance = Instance::resolve_closure(
 711                                 fx.tcx,
 712                                 def_id,
 713                                 substs,
 714                                 ty::ClosureKind::FnOnce,
 715                             )
 716                             .expect("failed to normalize and resolve closure during codegen")
 717                             .polymorphize(fx.tcx);
 718                             let func_ref = fx.get_function_ref(instance);
 719                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 720                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 721                         }
 722                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 723                     }
 724                 }
 725                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 726                     let operand = codegen_operand(fx, operand);
 727                     operand.unsize_value(fx, lval);
 728                 }
 729                 Rvalue::Discriminant(place) => {
 730                     let place = codegen_place(fx, place);
 731                     let value = place.to_cvalue(fx);
 732                     let discr =
 733                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 734                     lval.write_cvalue(fx, discr);
 735                 }
 736                 Rvalue::Repeat(ref operand, times) => {
 737                     let operand = codegen_operand(fx, operand);
 738                     let times = fx
 739                         .monomorphize(times)
 740                         .eval(fx.tcx, ParamEnv::reveal_all())
 741                         .kind()
 742                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 743                         .unwrap();
 744                     if operand.layout().size.bytes() == 0 {
 745                         // Do nothing for ZST's
 746                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 747                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 748                         // FIXME use emit_small_memset where possible
 749                         let addr = lval.to_ptr().get_addr(fx);
 750                         let val = operand.load_scalar(fx);
 751                         fx.bcx.call_memset(fx.target_config, addr, val, times);
 752                     } else {
 753                         let loop_block = fx.bcx.create_block();
 754                         let loop_block2 = fx.bcx.create_block();
 755                         let done_block = fx.bcx.create_block();
 756                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 757                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 758                         fx.bcx.ins().jump(loop_block, &[zero]);
 759
 760                         fx.bcx.switch_to_block(loop_block);
 761                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 762                         fx.bcx.ins().brnz(done, done_block, &[]);
 763                         fx.bcx.ins().jump(loop_block2, &[]);
 764
 765                         fx.bcx.switch_to_block(loop_block2);
 766                         let to = lval.place_index(fx, index);
 767                         to.write_cvalue(fx, operand);
 768                         let index = fx.bcx.ins().iadd_imm(index, 1);
 769                         fx.bcx.ins().jump(loop_block, &[index]);
 770
 771                         fx.bcx.switch_to_block(done_block);
 772                         fx.bcx.ins().nop();
 773                     }
 774                 }
 775                 Rvalue::Len(place) => {
 776                     let place = codegen_place(fx, place);
 777                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 778                     let len = codegen_array_len(fx, place);
 779                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 780                 }
 781                 Rvalue::ShallowInitBox(ref operand, content_ty) => {
 782                     let content_ty = fx.monomorphize(content_ty);
 783                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 784                     let operand = codegen_operand(fx, operand);
 785                     let operand = operand.load_scalar(fx);
 786                     lval.write_cvalue(fx, CValue::by_val(operand, box_layout));
 787                 }
 788                 Rvalue::NullaryOp(null_op, ty) => {
 789                     assert!(
 790                         lval.layout()
 791                             .ty
 792                             .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all())
 793                     );
 794                     let layout = fx.layout_of(fx.monomorphize(ty));
 795                     let val = match null_op {
 796                         NullOp::SizeOf => layout.size.bytes(),
 797                         NullOp::AlignOf => layout.align.abi.bytes(),
 798                     };
 799                     let val = CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), val.into());
 800                     lval.write_cvalue(fx, val);
 801                 }
 802                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 803                     AggregateKind::Array(_ty) => {
 804                         for (i, operand) in operands.iter().enumerate() {
 805                             let operand = codegen_operand(fx, operand);
 806                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 807                             let to = lval.place_index(fx, index);
 808                             to.write_cvalue(fx, operand);
 809                         }
 810                     }
 811                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 812                 },
 813             }
 814         }
 815         StatementKind::StorageLive(_)
 816         | StatementKind::StorageDead(_)
 817         | StatementKind::Deinit(_)
 818         | StatementKind::Nop
 819         | StatementKind::FakeRead(..)
 820         | StatementKind::Retag { .. }
 821         | StatementKind::AscribeUserType(..) => {}
 822
 823         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 824         StatementKind::CopyNonOverlapping(inner) => {
 825             let dst = codegen_operand(fx, &inner.dst);
 826             let pointee = dst
 827                 .layout()
 828                 .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 829                 .expect("Expected pointer");
 830             let dst = dst.load_scalar(fx);
 831             let src = codegen_operand(fx, &inner.src).load_scalar(fx);
 832             let count = codegen_operand(fx, &inner.count).load_scalar(fx);
 833             let elem_size: u64 = pointee.size.bytes();
 834             let bytes =
 835                 if elem_size != 1 { fx.bcx.ins().imul_imm(count, elem_size as i64) } else { count };
 836             fx.bcx.call_memcpy(fx.target_config, dst, src, bytes);
 837         }
 838     }
 839 }
 840
 841 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 842     match *place.layout().ty.kind() {
 843         ty::Array(_elem_ty, len) => {
 844             let len = fx.monomorphize(len).eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 845             fx.bcx.ins().iconst(fx.pointer_type, len)
 846         }
 847         ty::Slice(_elem_ty) => {
 848             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 849         }
 850         _ => bug!("Rvalue::Len({:?})", place),
 851     }
 852 }
 853
 854 pub(crate) fn codegen_place<'tcx>(
 855     fx: &mut FunctionCx<'_, '_, 'tcx>,
 856     place: Place<'tcx>,
 857 ) -> CPlace<'tcx> {
 858     let mut cplace = fx.get_local_place(place.local);
 859
 860     for elem in place.projection {
 861         match elem {
 862             PlaceElem::Deref => {
 863                 cplace = cplace.place_deref(fx);
 864             }
 865             PlaceElem::Field(field, _ty) => {
 866                 cplace = cplace.place_field(fx, field);
 867             }
 868             PlaceElem::Index(local) => {
 869                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 870                 cplace = cplace.place_index(fx, index);
 871             }
 872             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 873                 let offset: u64 = offset;
 874                 let index = if !from_end {
 875                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 876                 } else {
 877                     let len = codegen_array_len(fx, cplace);
 878                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 879                 };
 880                 cplace = cplace.place_index(fx, index);
 881             }
 882             PlaceElem::Subslice { from, to, from_end } => {
 883                 // These indices are generated by slice patterns.
 884                 // slice[from:-to] in Python terms.
 885
 886                 let from: u64 = from;
 887                 let to: u64 = to;
 888
 889                 match cplace.layout().ty.kind() {
 890                     ty::Array(elem_ty, _len) => {
 891                         assert!(!from_end, "array subslices are never `from_end`");
 892                         let elem_layout = fx.layout_of(*elem_ty);
 893                         let ptr = cplace.to_ptr();
 894                         cplace = CPlace::for_ptr(
 895                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 896                             fx.layout_of(fx.tcx.mk_array(*elem_ty, to - from)),
 897                         );
 898                     }
 899                     ty::Slice(elem_ty) => {
 900                         assert!(from_end, "slice subslices should be `from_end`");
 901                         let elem_layout = fx.layout_of(*elem_ty);
 902                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 903                         let len = len.unwrap();
 904                         cplace = CPlace::for_ptr_with_extra(
 905                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 906                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 907                             cplace.layout(),
 908                         );
 909                     }
 910                     _ => unreachable!(),
 911                 }
 912             }
 913             PlaceElem::Downcast(_adt_def, variant) => {
 914                 cplace = cplace.downcast_variant(fx, variant);
 915             }
 916         }
 917     }
 918
 919     cplace
 920 }
 921
 922 pub(crate) fn codegen_operand<'tcx>(
 923     fx: &mut FunctionCx<'_, '_, 'tcx>,
 924     operand: &Operand<'tcx>,
 925 ) -> CValue<'tcx> {
 926     match operand {
 927         Operand::Move(place) | Operand::Copy(place) => {
 928             let cplace = codegen_place(fx, *place);
 929             cplace.to_cvalue(fx)
 930         }
 931         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 932     }
 933 }
 934
 935 pub(crate) fn codegen_panic<'tcx>(
 936     fx: &mut FunctionCx<'_, '_, 'tcx>,
 937     msg_str: &str,
 938     source_info: mir::SourceInfo,
 939 ) {
 940     let location = fx.get_caller_location(source_info).load_scalar(fx);
 941
 942     let msg_ptr = fx.anonymous_str(msg_str);
 943     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 944     let args = [msg_ptr, msg_len, location];
 945
 946     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
 947 }
 948
 949 pub(crate) fn codegen_panic_inner<'tcx>(
 950     fx: &mut FunctionCx<'_, '_, 'tcx>,
 951     lang_item: rustc_hir::LangItem,
 952     args: &[Value],
 953     span: Span,
 954 ) {
 955     let def_id =
 956         fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
 957
 958     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 959     let symbol_name = fx.tcx.symbol_name(instance).name;
 960
 961     fx.lib_call(
 962         &*symbol_name,
 963         vec![
 964             AbiParam::new(fx.pointer_type),
 965             AbiParam::new(fx.pointer_type),
 966             AbiParam::new(fx.pointer_type),
 967         ],
 968         vec![],
 969         args,
 970     );
 971
 972     fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
 973 }