src/base.rs

   1 use rustc::ty::adjustment::PointerCast;
   2
   3 use crate::prelude::*;
   4
   5 pub fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
   6     cx: &mut crate::CodegenCx<'clif, 'tcx, B>,
   7     instance: Instance<'tcx>,
   8     linkage: Linkage,
   9 ) {
  10     let tcx = cx.tcx;
  11
  12     let mir = *tcx.instance_mir(instance.def);
  13
  14     // Declare function
  15     let (name, sig) = get_function_name_and_sig(tcx, instance, false);
  16     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  17     let mut debug_context = cx
  18         .debug_context
  19         .as_mut()
  20         .map(|debug_context| FunctionDebugContext::new(tcx, debug_context, mir, func_id, &name, &sig));
  21
  22     // Make FunctionBuilder
  23     let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
  24     let mut func_ctx = FunctionBuilderContext::new();
  25     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  26
  27     // Predefine ebb's
  28     let start_ebb = bcx.create_ebb();
  29     let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
  30     for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
  31         ebb_map.insert(bb, bcx.create_ebb());
  32     }
  33
  34     // Make FunctionCx
  35     let pointer_type = cx.module.target_config().pointer_type();
  36     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  37
  38     let mut fx = FunctionCx {
  39         tcx,
  40         module: cx.module,
  41         pointer_type,
  42
  43         instance,
  44         mir,
  45
  46         bcx,
  47         ebb_map,
  48         local_map: HashMap::new(),
  49
  50         clif_comments,
  51         constants_cx: &mut cx.constants_cx,
  52         caches: &mut cx.caches,
  53         source_info_set: indexmap::IndexSet::new(),
  54     };
  55
  56     crate::abi::codegen_fn_prelude(&mut fx, start_ebb);
  57     codegen_fn_content(&mut fx);
  58
  59     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  60     let instance = fx.instance;
  61     let clif_comments = fx.clif_comments;
  62     let source_info_set = fx.source_info_set;
  63
  64     #[cfg(debug_assertions)]
  65     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &func, &clif_comments, None);
  66
  67     // Verify function
  68     verify_func(tcx, &clif_comments, &func);
  69
  70     // Define function
  71     let context = &mut cx.caches.context;
  72     context.func = func;
  73     cx.module.define_function(func_id, context).unwrap();
  74
  75     let value_ranges = context
  76         .build_value_labels_ranges(cx.module.isa())
  77         .expect("value location ranges");
  78
  79     // Write optimized function to file for debugging
  80     #[cfg(debug_assertions)]
  81     crate::pretty_clif::write_clif_file(
  82         cx.tcx,
  83         "opt",
  84         instance,
  85         &context.func,
  86         &clif_comments,
  87         Some(&value_ranges),
  88     );
  89
  90     // Define debuginfo for function
  91     let isa = cx.module.isa();
  92     debug_context
  93         .as_mut()
  94         .map(|x| x.define(tcx, context, isa, &source_info_set));
  95
  96     // Clear context to make it usable for the next function
  97     context.clear();
  98 }
  99
 100 fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 101     let flags = settings::Flags::new(settings::builder());
 102     match ::cranelift::codegen::verify_function(&func, &flags) {
 103         Ok(_) => {}
 104         Err(err) => {
 105             tcx.sess.err(&format!("{:?}", err));
 106             let pretty_error = ::cranelift::codegen::print_errors::pretty_verifier_error(
 107                 &func,
 108                 None,
 109                 Some(Box::new(writer)),
 110                 err,
 111             );
 112             tcx.sess
 113                 .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 114         }
 115     }
 116 }
 117
 118 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 119     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 120         if bb_data.is_cleanup {
 121             // Unwinding after panicking is not supported
 122             continue;
 123         }
 124
 125         let ebb = fx.get_ebb(bb);
 126         fx.bcx.switch_to_block(ebb);
 127
 128         fx.bcx.ins().nop();
 129         for stmt in &bb_data.statements {
 130             fx.set_debug_loc(stmt.source_info);
 131             trans_stmt(fx, ebb, stmt);
 132         }
 133
 134         #[cfg(debug_assertions)]
 135         {
 136             let mut terminator_head = "\n".to_string();
 137             bb_data
 138                 .terminator()
 139                 .kind
 140                 .fmt_head(&mut terminator_head)
 141                 .unwrap();
 142             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 143             fx.add_comment(inst, terminator_head);
 144         }
 145
 146         fx.set_debug_loc(bb_data.terminator().source_info);
 147
 148         match &bb_data.terminator().kind {
 149             TerminatorKind::Goto { target } => {
 150                 let ebb = fx.get_ebb(*target);
 151                 fx.bcx.ins().jump(ebb, &[]);
 152             }
 153             TerminatorKind::Return => {
 154                 crate::abi::codegen_return(fx);
 155             }
 156             TerminatorKind::Assert {
 157                 cond,
 158                 expected,
 159                 msg,
 160                 target,
 161                 cleanup: _,
 162             } => {
 163                 if !fx.tcx.sess.overflow_checks() {
 164                     if let mir::interpret::PanicInfo::OverflowNeg = *msg {
 165                         let target = fx.get_ebb(*target);
 166                         fx.bcx.ins().jump(target, &[]);
 167                         continue;
 168                     }
 169                 }
 170                 let cond = trans_operand(fx, cond).load_scalar(fx);
 171                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 172                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 173                 let target = fx.get_ebb(*target);
 174                 if *expected {
 175                     fx.bcx.ins().brnz(cond, target, &[]);
 176                 } else {
 177                     fx.bcx.ins().brz(cond, target, &[]);
 178                 };
 179                 trap_panic(
 180                     fx,
 181                     format!(
 182                         "[panic] Assert {:?} at {:?} failed.",
 183                         msg,
 184                         bb_data.terminator().source_info.span
 185                     ),
 186                 );
 187             }
 188
 189             TerminatorKind::SwitchInt {
 190                 discr,
 191                 switch_ty: _,
 192                 values,
 193                 targets,
 194             } => {
 195                 let discr = trans_operand(fx, discr).load_scalar(fx);
 196                 let mut switch = ::cranelift::frontend::Switch::new();
 197                 for (i, value) in values.iter().enumerate() {
 198                     let ebb = fx.get_ebb(targets[i]);
 199                     switch.set_entry(*value as u64, ebb);
 200                 }
 201                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 202                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 203             }
 204             TerminatorKind::Call {
 205                 func,
 206                 args,
 207                 destination,
 208                 cleanup: _,
 209                 from_hir_call: _,
 210             } => {
 211                 crate::abi::codegen_terminator_call(
 212                     fx,
 213                     func,
 214                     args,
 215                     destination,
 216                     bb_data.terminator().source_info.span,
 217                 );
 218             }
 219             TerminatorKind::Resume | TerminatorKind::Abort => {
 220                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 221             }
 222             TerminatorKind::Unreachable => {
 223                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 224             }
 225             TerminatorKind::Yield { .. }
 226             | TerminatorKind::FalseEdges { .. }
 227             | TerminatorKind::FalseUnwind { .. }
 228             | TerminatorKind::DropAndReplace { .. }
 229             | TerminatorKind::GeneratorDrop => {
 230                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 231             }
 232             TerminatorKind::Drop {
 233                 location,
 234                 target,
 235                 unwind: _,
 236             } => {
 237                 let drop_place = trans_place(fx, location);
 238                 crate::abi::codegen_drop(fx, drop_place);
 239
 240                 let target_ebb = fx.get_ebb(*target);
 241                 fx.bcx.ins().jump(target_ebb, &[]);
 242             }
 243         };
 244     }
 245
 246     fx.bcx.seal_all_blocks();
 247     fx.bcx.finalize();
 248 }
 249
 250 fn trans_stmt<'tcx>(
 251     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 252     cur_ebb: Ebb,
 253     stmt: &Statement<'tcx>,
 254 ) {
 255     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 256
 257     fx.set_debug_loc(stmt.source_info);
 258
 259     #[cfg(debug_assertions)]
 260     match &stmt.kind {
 261         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 262         _ => {
 263             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 264             fx.add_comment(inst, format!("{:?}", stmt));
 265         }
 266     }
 267
 268     match &stmt.kind {
 269         StatementKind::SetDiscriminant {
 270             place,
 271             variant_index,
 272         } => {
 273             let place = trans_place(fx, place);
 274             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 275         }
 276         StatementKind::Assign(to_place_and_rval) => {
 277             let lval = trans_place(fx, &to_place_and_rval.0);
 278             let dest_layout = lval.layout();
 279             match &to_place_and_rval.1 {
 280                 Rvalue::Use(operand) => {
 281                     let val = trans_operand(fx, operand);
 282                     lval.write_cvalue(fx, val);
 283                 }
 284                 Rvalue::Ref(_, _, place) => {
 285                     let place = trans_place(fx, place);
 286                     place.write_place_ref(fx, lval);
 287                 }
 288                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 289                     let lhs = trans_operand(fx, lhs);
 290                     let rhs = trans_operand(fx, rhs);
 291
 292                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 293                     lval.write_cvalue(fx, res);
 294                 }
 295                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 296                     let lhs = trans_operand(fx, lhs);
 297                     let rhs = trans_operand(fx, rhs);
 298
 299                     let res = if !fx.tcx.sess.overflow_checks() {
 300                         let val =
 301                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 302                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 303                         CValue::by_val_pair(val, is_overflow, lval.layout())
 304                     } else {
 305                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 306                     };
 307
 308                     lval.write_cvalue(fx, res);
 309                 }
 310                 Rvalue::UnaryOp(un_op, operand) => {
 311                     let operand = trans_operand(fx, operand);
 312                     let layout = operand.layout();
 313                     let val = operand.load_scalar(fx);
 314                     let res = match un_op {
 315                         UnOp::Not => {
 316                             match layout.ty.kind {
 317                                 ty::Bool => {
 318                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 319                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 320                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 321                                 }
 322                                 ty::Uint(_) | ty::Int(_) => {
 323                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 324                                 }
 325                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 326                             }
 327                         }
 328                         UnOp::Neg => match layout.ty.kind {
 329                             ty::Int(_) => {
 330                                 let zero = CValue::const_val(fx, layout.ty, 0);
 331                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 332                             }
 333                             ty::Float(_) => {
 334                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 335                             }
 336                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 337                         },
 338                     };
 339                     lval.write_cvalue(fx, res);
 340                 }
 341                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 342                     let layout = fx.layout_of(ty);
 343                     match fx
 344                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 345                         .kind
 346                     {
 347                         ty::FnDef(def_id, substs) => {
 348                             let func_ref = fx.get_function_ref(
 349                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 350                                     .unwrap(),
 351                             );
 352                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 353                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 354                         }
 355                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 356                     }
 357                 }
 358                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 359                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty)
 360                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, ty) => {
 361                     let operand = trans_operand(fx, operand);
 362                     let layout = fx.layout_of(ty);
 363                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 364                 }
 365                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 366                     let operand = trans_operand(fx, operand);
 367                     let from_ty = operand.layout().ty;
 368                     let to_ty = fx.monomorphize(to_ty);
 369
 370                     fn is_fat_ptr<'tcx>(
 371                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 372                         ty: Ty<'tcx>,
 373                     ) -> bool {
 374                         ty.builtin_deref(true)
 375                             .map(
 376                                 |ty::TypeAndMut {
 377                                      ty: pointee_ty,
 378                                      mutbl: _,
 379                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 380                             )
 381                             .unwrap_or(false)
 382                     }
 383
 384                     if is_fat_ptr(fx, from_ty) {
 385                         if is_fat_ptr(fx, to_ty) {
 386                             // fat-ptr -> fat-ptr
 387                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 388                         } else {
 389                             // fat-ptr -> thin-ptr
 390                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 391                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 392                         }
 393                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 394                         // enum -> discriminant value
 395                         assert!(adt_def.is_enum());
 396                         match to_ty.kind {
 397                             ty::Uint(_) | ty::Int(_) => {}
 398                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 399                         }
 400
 401                         let discr = crate::discriminant::codegen_get_discriminant(
 402                             fx,
 403                             operand,
 404                             fx.layout_of(to_ty),
 405                         );
 406                         lval.write_cvalue(fx, discr);
 407                     } else {
 408                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 409                         let from = operand.load_scalar(fx);
 410
 411                         let res = clif_int_or_float_cast(
 412                             fx,
 413                             from,
 414                             type_sign(from_ty),
 415                             to_clif_ty,
 416                             type_sign(to_ty),
 417                         );
 418                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 419                     }
 420                 }
 421                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
 422                     let operand = trans_operand(fx, operand);
 423                     match operand.layout().ty.kind {
 424                         ty::Closure(def_id, substs) => {
 425                             let instance = Instance::resolve_closure(
 426                                 fx.tcx,
 427                                 def_id,
 428                                 substs,
 429                                 ty::ClosureKind::FnOnce,
 430                             );
 431                             let func_ref = fx.get_function_ref(instance);
 432                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 433                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 434                         }
 435                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 436                     }
 437                 }
 438                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
 439                     let operand = trans_operand(fx, operand);
 440                     operand.unsize_value(fx, lval);
 441                 }
 442                 Rvalue::Discriminant(place) => {
 443                     let place = trans_place(fx, place);
 444                     let value = place.to_cvalue(fx);
 445                     let discr =
 446                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 447                     lval.write_cvalue(fx, discr);
 448                 }
 449                 Rvalue::Repeat(operand, times) => {
 450                     let operand = trans_operand(fx, operand);
 451                     for i in 0..*times {
 452                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 453                         let to = lval.place_index(fx, index);
 454                         to.write_cvalue(fx, operand);
 455                     }
 456                 }
 457                 Rvalue::Len(place) => {
 458                     let place = trans_place(fx, place);
 459                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 460                     let len = codegen_array_len(fx, place);
 461                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 462                 }
 463                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 464                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 465
 466                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 467                     let layout = fx.layout_of(content_ty);
 468                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 469                     let llalign = fx
 470                         .bcx
 471                         .ins()
 472                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 473                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 474
 475                     // Allocate space:
 476                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 477                         Ok(id) => id,
 478                         Err(s) => {
 479                             fx.tcx
 480                                 .sess
 481                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 482                         }
 483                     };
 484                     let instance = ty::Instance::mono(fx.tcx, def_id);
 485                     let func_ref = fx.get_function_ref(instance);
 486                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 487                     let ptr = fx.bcx.inst_results(call)[0];
 488                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 489                 }
 490                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 491                     assert!(lval
 492                         .layout()
 493                         .ty
 494                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 495                     let ty_size = fx.layout_of(ty).size.bytes();
 496                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size.into());
 497                     lval.write_cvalue(fx, val);
 498                 }
 499                 Rvalue::Aggregate(kind, operands) => match **kind {
 500                     AggregateKind::Array(_ty) => {
 501                         for (i, operand) in operands.into_iter().enumerate() {
 502                             let operand = trans_operand(fx, operand);
 503                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 504                             let to = lval.place_index(fx, index);
 505                             to.write_cvalue(fx, operand);
 506                         }
 507                     }
 508                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 509                 },
 510             }
 511         }
 512         StatementKind::StorageLive(_)
 513         | StatementKind::StorageDead(_)
 514         | StatementKind::Nop
 515         | StatementKind::FakeRead(..)
 516         | StatementKind::Retag { .. }
 517         | StatementKind::AscribeUserType(..) => {}
 518
 519         StatementKind::InlineAsm(asm) => {
 520             use syntax::ast::Name;
 521             let InlineAsm {
 522                 asm,
 523                 outputs: _,
 524                 inputs: _,
 525             } = &**asm;
 526             let rustc::hir::InlineAsmInner {
 527                 asm: asm_code, // Name
 528                 outputs,       // Vec<Name>
 529                 inputs,        // Vec<Name>
 530                 clobbers,      // Vec<Name>
 531                 volatile,      // bool
 532                 alignstack,    // bool
 533                 dialect: _,    // syntax::ast::AsmDialect
 534                 asm_str_style: _,
 535             } = asm;
 536             match &*asm_code.as_str() {
 537                 "" => {
 538                     assert_eq!(inputs, &[Name::intern("r")]);
 539                     assert!(outputs.is_empty(), "{:?}", outputs);
 540
 541                     // Black box
 542                 }
 543                 "cpuid" | "cpuid\n" => {
 544                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 545
 546                     assert_eq!(outputs.len(), 4);
 547                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 548                         .iter()
 549                         .enumerate()
 550                     {
 551                         assert_eq!(&outputs[i].constraint.as_str(), c);
 552                         assert!(!outputs[i].is_rw);
 553                         assert!(!outputs[i].is_indirect);
 554                     }
 555
 556                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 557
 558                     assert!(!volatile);
 559                     assert!(!alignstack);
 560
 561                     crate::trap::trap_unimplemented(
 562                         fx,
 563                         "__cpuid_count arch intrinsic is not supported",
 564                     );
 565                 }
 566                 "xgetbv" => {
 567                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 568
 569                     assert_eq!(outputs.len(), 2);
 570                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 571                         assert_eq!(&outputs[i].constraint.as_str(), c);
 572                         assert!(!outputs[i].is_rw);
 573                         assert!(!outputs[i].is_indirect);
 574                     }
 575
 576                     assert_eq!(clobbers, &[]);
 577
 578                     assert!(!volatile);
 579                     assert!(!alignstack);
 580
 581                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 582                 }
 583                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__rust_probestack" => {
 584                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 585                 }
 586                 _ => unimpl!("Inline assembly is not supported"),
 587             }
 588         }
 589     }
 590 }
 591
 592 fn codegen_array_len<'tcx>(
 593     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 594     place: CPlace<'tcx>,
 595 ) -> Value {
 596     match place.layout().ty.kind {
 597         ty::Array(_elem_ty, len) => {
 598             let len = crate::constant::force_eval_const(fx, len)
 599                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 600             fx.bcx.ins().iconst(fx.pointer_type, len)
 601         }
 602         ty::Slice(_elem_ty) => place
 603             .to_addr_maybe_unsized(fx)
 604             .1
 605             .expect("Length metadata for slice place"),
 606         _ => bug!("Rvalue::Len({:?})", place),
 607     }
 608 }
 609
 610 pub fn trans_place<'tcx>(
 611     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 612     place: &Place<'tcx>,
 613 ) -> CPlace<'tcx> {
 614     let mut cplace = match &place.base {
 615         PlaceBase::Local(local) => fx.get_local_place(*local),
 616         PlaceBase::Static(static_) => match static_.kind {
 617             StaticKind::Static => {
 618                 crate::constant::codegen_static_ref(fx, static_.def_id, static_.ty)
 619             }
 620             StaticKind::Promoted(promoted, substs) => {
 621                 let instance = Instance::new(static_.def_id, fx.monomorphize(&substs));
 622                 crate::constant::trans_promoted(fx, instance, promoted, static_.ty)
 623             }
 624         },
 625     };
 626
 627     for elem in &*place.projection {
 628         match *elem {
 629             PlaceElem::Deref => {
 630                 cplace = cplace.place_deref(fx);
 631             }
 632             PlaceElem::Field(field, _ty) => {
 633                 cplace = cplace.place_field(fx, field);
 634             }
 635             PlaceElem::Index(local) => {
 636                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 637                 cplace = cplace.place_index(fx, index);
 638             }
 639             PlaceElem::ConstantIndex {
 640                 offset,
 641                 min_length: _,
 642                 from_end,
 643             } => {
 644                 let index = if !from_end {
 645                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 646                 } else {
 647                     let len = codegen_array_len(fx, cplace);
 648                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 649                 };
 650                 cplace = cplace.place_index(fx, index);
 651             }
 652             PlaceElem::Subslice { from, to } => {
 653                 // These indices are generated by slice patterns.
 654                 // slice[from:-to] in Python terms.
 655
 656                 match cplace.layout().ty.kind {
 657                     ty::Array(elem_ty, len) => {
 658                         let elem_layout = fx.layout_of(elem_ty);
 659                         let ptr = cplace.to_addr(fx);
 660                         let len = crate::constant::force_eval_const(fx, len)
 661                             .eval_usize(fx.tcx, ParamEnv::reveal_all());
 662                         cplace = CPlace::for_addr(
 663                             fx.bcx
 664                                 .ins()
 665                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 666                             fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
 667                         );
 668                     }
 669                     ty::Slice(elem_ty) => {
 670                         let elem_layout = fx.layout_of(elem_ty);
 671                         let (ptr, len) = cplace.to_addr_maybe_unsized(fx);
 672                         let len = len.unwrap();
 673                         cplace = CPlace::for_addr_with_extra(
 674                             fx.bcx
 675                                 .ins()
 676                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 677                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 678                             cplace.layout(),
 679                         );
 680                     }
 681                     _ => unreachable!(),
 682                 }
 683             }
 684             PlaceElem::Downcast(_adt_def, variant) => {
 685                 cplace = cplace.downcast_variant(fx, variant);
 686             }
 687         }
 688     }
 689
 690     cplace
 691 }
 692
 693 pub fn trans_operand<'tcx>(
 694     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 695     operand: &Operand<'tcx>,
 696 ) -> CValue<'tcx> {
 697     match operand {
 698         Operand::Move(place) | Operand::Copy(place) => {
 699             let cplace = trans_place(fx, place);
 700             cplace.to_cvalue(fx)
 701         }
 702         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 703     }
 704 }