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, &name, &sig));
  21
  22     // FIXME reuse Function and FunctionBuilder between multiple trans_fn calls
  23     let mut bcx = FunctionBuilder::new(Function::with_name_signature(ExternalName::user(0, 0), sig));
  24
  25     // Predefine ebb's
  26     let start_ebb = bcx.create_ebb();
  27     let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
  28     for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
  29         ebb_map.insert(bb, bcx.create_ebb());
  30     }
  31
  32     // Make FunctionCx
  33     let pointer_type = cx.module.target_config().pointer_type();
  34     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  35
  36     let mut fx = FunctionCx {
  37         tcx,
  38         module: cx.module,
  39         pointer_type,
  40
  41         instance,
  42         mir,
  43
  44         bcx,
  45         ebb_map,
  46         local_map: HashMap::new(),
  47
  48         clif_comments,
  49         constants_cx: &mut cx.constants_cx,
  50         caches: &mut cx.caches,
  51         source_info_set: indexmap::IndexSet::new(),
  52     };
  53
  54     with_unimpl_span(fx.mir.span, || {
  55         crate::abi::codegen_fn_prelude(&mut fx, start_ebb);
  56         codegen_fn_content(&mut fx);
  57     });
  58
  59     fx.bcx.seal_all_blocks();
  60     let func = fx.bcx.finalize();
  61
  62     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  63     let instance = fx.instance;
  64     let clif_comments = fx.clif_comments;
  65     let source_info_set = fx.source_info_set;
  66
  67     #[cfg(debug_assertions)]
  68     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &func, &clif_comments, None);
  69
  70     // Verify function
  71     verify_func(tcx, &clif_comments, &func);
  72
  73     // Define function
  74     let context = &mut cx.caches.context;
  75     context.func = func;
  76     cx.module.define_function(func_id, context).unwrap();
  77
  78     let value_ranges = context
  79         .build_value_labels_ranges(cx.module.isa())
  80         .expect("value location ranges");
  81
  82     // Write optimized function to file for debugging
  83     #[cfg(debug_assertions)]
  84     crate::pretty_clif::write_clif_file(
  85         cx.tcx,
  86         "opt",
  87         instance,
  88         &context.func,
  89         &clif_comments,
  90         Some(&value_ranges),
  91     );
  92
  93     // Define debuginfo for function
  94     let isa = cx.module.isa();
  95     debug_context
  96         .as_mut()
  97         .map(|x| x.define(tcx, context, isa, &source_info_set));
  98
  99     // Clear context to make it usable for the next function
 100     context.clear();
 101 }
 102
 103 fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 104     let flags = settings::Flags::new(settings::builder());
 105     match ::cranelift::codegen::verify_function(&func, &flags) {
 106         Ok(_) => {}
 107         Err(err) => {
 108             tcx.sess.err(&format!("{:?}", err));
 109             let pretty_error = ::cranelift::codegen::print_errors::pretty_verifier_error(
 110                 &func,
 111                 None,
 112                 Some(Box::new(writer)),
 113                 err,
 114             );
 115             tcx.sess
 116                 .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 117         }
 118     }
 119 }
 120
 121 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 122     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 123         if bb_data.is_cleanup {
 124             // Unwinding after panicking is not supported
 125             continue;
 126         }
 127
 128         let ebb = fx.get_ebb(bb);
 129         fx.bcx.switch_to_block(ebb);
 130
 131         fx.bcx.ins().nop();
 132         for stmt in &bb_data.statements {
 133             fx.set_debug_loc(stmt.source_info);
 134             trans_stmt(fx, ebb, stmt);
 135         }
 136
 137         #[cfg(debug_assertions)]
 138         {
 139             let mut terminator_head = "\n".to_string();
 140             bb_data
 141                 .terminator()
 142                 .kind
 143                 .fmt_head(&mut terminator_head)
 144                 .unwrap();
 145             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 146             fx.add_comment(inst, terminator_head);
 147         }
 148
 149         fx.set_debug_loc(bb_data.terminator().source_info);
 150
 151         match &bb_data.terminator().kind {
 152             TerminatorKind::Goto { target } => {
 153                 let ebb = fx.get_ebb(*target);
 154                 fx.bcx.ins().jump(ebb, &[]);
 155             }
 156             TerminatorKind::Return => {
 157                 crate::abi::codegen_return(fx);
 158             }
 159             TerminatorKind::Assert {
 160                 cond,
 161                 expected,
 162                 msg,
 163                 target,
 164                 cleanup: _,
 165             } => {
 166                 if !fx.tcx.sess.overflow_checks() {
 167                     if let mir::interpret::PanicInfo::OverflowNeg = *msg {
 168                         let target = fx.get_ebb(*target);
 169                         fx.bcx.ins().jump(target, &[]);
 170                         continue;
 171                     }
 172                 }
 173                 let cond = trans_operand(fx, cond).load_scalar(fx);
 174                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 175                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 176                 let target = fx.get_ebb(*target);
 177                 if *expected {
 178                     fx.bcx.ins().brnz(cond, target, &[]);
 179                 } else {
 180                     fx.bcx.ins().brz(cond, target, &[]);
 181                 };
 182                 trap_panic(
 183                     fx,
 184                     format!(
 185                         "[panic] Assert {:?} at {:?} failed.",
 186                         msg,
 187                         bb_data.terminator().source_info.span
 188                     ),
 189                 );
 190             }
 191
 192             TerminatorKind::SwitchInt {
 193                 discr,
 194                 switch_ty: _,
 195                 values,
 196                 targets,
 197             } => {
 198                 let discr = trans_operand(fx, discr).load_scalar(fx);
 199                 let mut switch = ::cranelift::frontend::Switch::new();
 200                 for (i, value) in values.iter().enumerate() {
 201                     let ebb = fx.get_ebb(targets[i]);
 202                     switch.set_entry(*value as u64, ebb);
 203                 }
 204                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 205                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 206             }
 207             TerminatorKind::Call {
 208                 func,
 209                 args,
 210                 destination,
 211                 cleanup: _,
 212                 from_hir_call: _,
 213             } => {
 214                 crate::abi::codegen_terminator_call(fx, func, args, destination);
 215             }
 216             TerminatorKind::Resume | TerminatorKind::Abort => {
 217                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 218             }
 219             TerminatorKind::Unreachable => {
 220                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 221             }
 222             TerminatorKind::Yield { .. }
 223             | TerminatorKind::FalseEdges { .. }
 224             | TerminatorKind::FalseUnwind { .. }
 225             | TerminatorKind::DropAndReplace { .. }
 226             | TerminatorKind::GeneratorDrop => {
 227                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 228             }
 229             TerminatorKind::Drop {
 230                 location,
 231                 target,
 232                 unwind: _,
 233             } => {
 234                 let drop_place = trans_place(fx, location);
 235                 crate::abi::codegen_drop(fx, drop_place);
 236
 237                 let target_ebb = fx.get_ebb(*target);
 238                 fx.bcx.ins().jump(target_ebb, &[]);
 239             }
 240         };
 241     }
 242 }
 243
 244 fn trans_stmt<'tcx>(
 245     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 246     cur_ebb: Ebb,
 247     stmt: &Statement<'tcx>,
 248 ) {
 249     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 250
 251     fx.set_debug_loc(stmt.source_info);
 252
 253     #[cfg(debug_assertions)]
 254     match &stmt.kind {
 255         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 256         _ => {
 257             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 258             fx.add_comment(inst, format!("{:?}", stmt));
 259         }
 260     }
 261
 262     match &stmt.kind {
 263         StatementKind::SetDiscriminant {
 264             place,
 265             variant_index,
 266         } => {
 267             let place = trans_place(fx, place);
 268             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 269         }
 270         StatementKind::Assign(to_place_and_rval) => {
 271             let lval = trans_place(fx, &to_place_and_rval.0);
 272             let dest_layout = lval.layout();
 273             match &to_place_and_rval.1 {
 274                 Rvalue::Use(operand) => {
 275                     let val = trans_operand(fx, operand);
 276                     lval.write_cvalue(fx, val);
 277                 }
 278                 Rvalue::Ref(_, _, place) => {
 279                     let place = trans_place(fx, place);
 280                     place.write_place_ref(fx, lval);
 281                 }
 282                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 283                     let lhs = trans_operand(fx, lhs);
 284                     let rhs = trans_operand(fx, rhs);
 285
 286                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 287                     lval.write_cvalue(fx, res);
 288                 }
 289                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 290                     let lhs = trans_operand(fx, lhs);
 291                     let rhs = trans_operand(fx, rhs);
 292
 293                     let res = if !fx.tcx.sess.overflow_checks() {
 294                         let val =
 295                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 296                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 297                         CValue::by_val_pair(val, is_overflow, lval.layout())
 298                     } else {
 299                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 300                     };
 301
 302                     lval.write_cvalue(fx, res);
 303                 }
 304                 Rvalue::UnaryOp(un_op, operand) => {
 305                     let operand = trans_operand(fx, operand);
 306                     let layout = operand.layout();
 307                     let val = operand.load_scalar(fx);
 308                     let res = match un_op {
 309                         UnOp::Not => {
 310                             match layout.ty.sty {
 311                                 ty::Bool => {
 312                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 313                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 314                                     fx.bcx.ins().bint(types::I8, res)
 315                                 }
 316                                 ty::Uint(_) | ty::Int(_) => fx.bcx.ins().bnot(val),
 317                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 318                             }
 319                         }
 320                         UnOp::Neg => match layout.ty.sty {
 321                             ty::Int(_) => {
 322                                 let clif_ty = fx.clif_type(layout.ty).unwrap();
 323                                 if clif_ty == types::I128 {
 324                                     // FIXME implement it
 325                                     crate::trap::trap_unreachable_ret_value(
 326                                         fx,
 327                                         layout,
 328                                         "i128 neg is not yet supported",
 329                                     )
 330                                     .load_scalar(fx)
 331                                 } else {
 332                                     let zero = fx.bcx.ins().iconst(clif_ty, 0);
 333                                     fx.bcx.ins().isub(zero, val)
 334                                 }
 335                             }
 336                             ty::Float(_) => fx.bcx.ins().fneg(val),
 337                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 338                         },
 339                     };
 340                     lval.write_cvalue(fx, CValue::by_val(res, layout));
 341                 }
 342                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 343                     let layout = fx.layout_of(ty);
 344                     match fx
 345                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 346                         .sty
 347                     {
 348                         ty::FnDef(def_id, substs) => {
 349                             let func_ref = fx.get_function_ref(
 350                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 351                                     .unwrap(),
 352                             );
 353                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 354                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 355                         }
 356                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 357                     }
 358                 }
 359                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 360                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), 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.sty {
 394                         // enum -> discriminant value
 395                         assert!(adt_def.is_enum());
 396                         match to_ty.sty {
 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.sty {
 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                     _ => unimpl!("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::InlineAsm {
 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                 "cpuid" | "cpuid\n" => {
 538                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 539
 540                     assert_eq!(outputs.len(), 4);
 541                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 542                         .iter()
 543                         .enumerate()
 544                     {
 545                         assert_eq!(&outputs[i].constraint.as_str(), c);
 546                         assert!(!outputs[i].is_rw);
 547                         assert!(!outputs[i].is_indirect);
 548                     }
 549
 550                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 551
 552                     assert!(!volatile);
 553                     assert!(!alignstack);
 554
 555                     crate::trap::trap_unimplemented(
 556                         fx,
 557                         "__cpuid_count arch intrinsic is not supported",
 558                     );
 559                 }
 560                 "xgetbv" => {
 561                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 562
 563                     assert_eq!(outputs.len(), 2);
 564                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 565                         assert_eq!(&outputs[i].constraint.as_str(), c);
 566                         assert!(!outputs[i].is_rw);
 567                         assert!(!outputs[i].is_indirect);
 568                     }
 569
 570                     assert_eq!(clobbers, &[]);
 571
 572                     assert!(!volatile);
 573                     assert!(!alignstack);
 574
 575                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 576                 }
 577                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__rust_probestack" => {
 578                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 579                 }
 580                 _ => unimpl!("Inline assembly is not supported"),
 581             }
 582         }
 583     }
 584 }
 585
 586 fn codegen_array_len<'tcx>(
 587     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 588     place: CPlace<'tcx>,
 589 ) -> Value {
 590     match place.layout().ty.sty {
 591         ty::Array(_elem_ty, len) => {
 592             let len = crate::constant::force_eval_const(fx, len)
 593                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 594             fx.bcx.ins().iconst(fx.pointer_type, len)
 595         }
 596         ty::Slice(_elem_ty) => place
 597             .to_addr_maybe_unsized(fx)
 598             .1
 599             .expect("Length metadata for slice place"),
 600         _ => bug!("Rvalue::Len({:?})", place),
 601     }
 602 }
 603
 604 pub fn trans_place<'tcx>(
 605     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 606     place: &Place<'tcx>,
 607 ) -> CPlace<'tcx> {
 608     let mut cplace = match &place.base {
 609         PlaceBase::Local(local) => fx.get_local_place(*local),
 610         PlaceBase::Static(static_) => match static_.kind {
 611             StaticKind::Static => {
 612                 crate::constant::codegen_static_ref(fx, static_.def_id, static_.ty)
 613             }
 614             StaticKind::Promoted(promoted, substs) => {
 615                 let instance = Instance::new(static_.def_id, fx.monomorphize(&substs));
 616                 crate::constant::trans_promoted(fx, instance, promoted, static_.ty)
 617             }
 618         },
 619     };
 620
 621     for elem in &*place.projection {
 622         match *elem {
 623             PlaceElem::Deref => {
 624                 cplace = cplace.place_deref(fx);
 625             }
 626             PlaceElem::Field(field, _ty) => {
 627                 cplace = cplace.place_field(fx, field);
 628             }
 629             PlaceElem::Index(local) => {
 630                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 631                 cplace = cplace.place_index(fx, index);
 632             }
 633             PlaceElem::ConstantIndex {
 634                 offset,
 635                 min_length: _,
 636                 from_end,
 637             } => {
 638                 let index = if !from_end {
 639                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 640                 } else {
 641                     let len = codegen_array_len(fx, cplace);
 642                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 643                 };
 644                 cplace = cplace.place_index(fx, index);
 645             }
 646             PlaceElem::Subslice { from, to } => {
 647                 // These indices are generated by slice patterns.
 648                 // slice[from:-to] in Python terms.
 649
 650                 match cplace.layout().ty.sty {
 651                     ty::Array(elem_ty, len) => {
 652                         let elem_layout = fx.layout_of(elem_ty);
 653                         let ptr = cplace.to_addr(fx);
 654                         let len = crate::constant::force_eval_const(fx, len)
 655                             .eval_usize(fx.tcx, ParamEnv::reveal_all());
 656                         cplace = CPlace::for_addr(
 657                             fx.bcx
 658                                 .ins()
 659                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 660                             fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
 661                         );
 662                     }
 663                     ty::Slice(elem_ty) => {
 664                         let elem_layout = fx.layout_of(elem_ty);
 665                         let (ptr, len) = cplace.to_addr_maybe_unsized(fx);
 666                         let len = len.unwrap();
 667                         cplace = CPlace::for_addr_with_extra(
 668                             fx.bcx
 669                                 .ins()
 670                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 671                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 672                             cplace.layout(),
 673                         );
 674                     }
 675                     _ => unreachable!(),
 676                 }
 677             }
 678             PlaceElem::Downcast(_adt_def, variant) => {
 679                 cplace = cplace.downcast_variant(fx, variant);
 680             }
 681         }
 682     }
 683
 684     cplace
 685 }
 686
 687 pub fn trans_operand<'tcx>(
 688     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 689     operand: &Operand<'tcx>,
 690 ) -> CValue<'tcx> {
 691     match operand {
 692         Operand::Move(place) | Operand::Copy(place) => {
 693             let cplace = trans_place(fx, place);
 694             cplace.to_cvalue(fx)
 695         }
 696         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 697     }
 698 }