compiler/rustc_codegen_cranelift/src/base.rs

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