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