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                 let target = fx.get_ebb(*target);
 172                 if *expected {
 173                     fx.bcx.ins().brnz(cond, target, &[]);
 174                 } else {
 175                     fx.bcx.ins().brz(cond, target, &[]);
 176                 };
 177                 trap_panic(
 178                     fx,
 179                     format!(
 180                         "[panic] Assert {:?} at {:?} failed.",
 181                         msg,
 182                         bb_data.terminator().source_info.span
 183                     ),
 184                 );
 185             }
 186
 187             TerminatorKind::SwitchInt {
 188                 discr,
 189                 switch_ty: _,
 190                 values,
 191                 targets,
 192             } => {
 193                 let discr = trans_operand(fx, discr).load_scalar(fx);
 194                 let mut switch = ::cranelift::frontend::Switch::new();
 195                 for (i, value) in values.iter().enumerate() {
 196                     let ebb = fx.get_ebb(targets[i]);
 197                     switch.set_entry(*value as u64, ebb);
 198                 }
 199                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 200                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 201             }
 202             TerminatorKind::Call {
 203                 func,
 204                 args,
 205                 destination,
 206                 cleanup: _,
 207                 from_hir_call: _,
 208             } => {
 209                 crate::abi::codegen_terminator_call(
 210                     fx,
 211                     func,
 212                     args,
 213                     destination,
 214                     bb_data.terminator().source_info.span,
 215                 );
 216             }
 217             TerminatorKind::Resume | TerminatorKind::Abort => {
 218                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 219             }
 220             TerminatorKind::Unreachable => {
 221                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 222             }
 223             TerminatorKind::Yield { .. }
 224             | TerminatorKind::FalseEdges { .. }
 225             | TerminatorKind::FalseUnwind { .. }
 226             | TerminatorKind::DropAndReplace { .. }
 227             | TerminatorKind::GeneratorDrop => {
 228                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 229             }
 230             TerminatorKind::Drop {
 231                 location,
 232                 target,
 233                 unwind: _,
 234             } => {
 235                 let drop_place = trans_place(fx, location);
 236                 crate::abi::codegen_drop(fx, drop_place);
 237
 238                 let target_ebb = fx.get_ebb(*target);
 239                 fx.bcx.ins().jump(target_ebb, &[]);
 240             }
 241         };
 242     }
 243
 244     fx.bcx.seal_all_blocks();
 245     fx.bcx.finalize();
 246 }
 247
 248 fn trans_stmt<'tcx>(
 249     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 250     cur_ebb: Ebb,
 251     stmt: &Statement<'tcx>,
 252 ) {
 253     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 254
 255     fx.set_debug_loc(stmt.source_info);
 256
 257     #[cfg(debug_assertions)]
 258     match &stmt.kind {
 259         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 260         _ => {
 261             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 262             fx.add_comment(inst, format!("{:?}", stmt));
 263         }
 264     }
 265
 266     match &stmt.kind {
 267         StatementKind::SetDiscriminant {
 268             place,
 269             variant_index,
 270         } => {
 271             let place = trans_place(fx, place);
 272             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 273         }
 274         StatementKind::Assign(to_place_and_rval) => {
 275             let lval = trans_place(fx, &to_place_and_rval.0);
 276             let dest_layout = lval.layout();
 277             match &to_place_and_rval.1 {
 278                 Rvalue::Use(operand) => {
 279                     let val = trans_operand(fx, operand);
 280                     lval.write_cvalue(fx, val);
 281                 }
 282                 Rvalue::Ref(_, _, place) => {
 283                     let place = trans_place(fx, place);
 284                     place.write_place_ref(fx, lval);
 285                 }
 286                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 287                     let lhs = trans_operand(fx, lhs);
 288                     let rhs = trans_operand(fx, rhs);
 289
 290                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 291                     lval.write_cvalue(fx, res);
 292                 }
 293                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 294                     let lhs = trans_operand(fx, lhs);
 295                     let rhs = trans_operand(fx, rhs);
 296
 297                     let res = if !fx.tcx.sess.overflow_checks() {
 298                         let val =
 299                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 300                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 301                         CValue::by_val_pair(val, is_overflow, lval.layout())
 302                     } else {
 303                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 304                     };
 305
 306                     lval.write_cvalue(fx, res);
 307                 }
 308                 Rvalue::UnaryOp(un_op, operand) => {
 309                     let operand = trans_operand(fx, operand);
 310                     let layout = operand.layout();
 311                     let val = operand.load_scalar(fx);
 312                     let res = match un_op {
 313                         UnOp::Not => {
 314                             match layout.ty.kind {
 315                                 ty::Bool => {
 316                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 317                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 318                                     CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 319                                 }
 320                                 ty::Uint(_) | ty::Int(_) => {
 321                                     CValue::by_val(fx.bcx.ins().bnot(val), layout)
 322                                 }
 323                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 324                             }
 325                         }
 326                         UnOp::Neg => match layout.ty.kind {
 327                             ty::Int(_) => {
 328                                 let zero = CValue::const_val(fx, layout.ty, 0);
 329                                 crate::num::trans_int_binop(fx, BinOp::Sub, zero, operand)
 330                             }
 331                             ty::Float(_) => {
 332                                 CValue::by_val(fx.bcx.ins().fneg(val), layout)
 333                             }
 334                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 335                         },
 336                     };
 337                     lval.write_cvalue(fx, res);
 338                 }
 339                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 340                     let layout = fx.layout_of(ty);
 341                     match fx
 342                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 343                         .kind
 344                     {
 345                         ty::FnDef(def_id, substs) => {
 346                             let func_ref = fx.get_function_ref(
 347                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 348                                     .unwrap(),
 349                             );
 350                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 351                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 352                         }
 353                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 354                     }
 355                 }
 356                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 357                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty)
 358                 | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, ty) => {
 359                     let operand = trans_operand(fx, operand);
 360                     let layout = fx.layout_of(ty);
 361                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 362                 }
 363                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 364                     let operand = trans_operand(fx, operand);
 365                     let from_ty = operand.layout().ty;
 366                     let to_ty = fx.monomorphize(to_ty);
 367
 368                     fn is_fat_ptr<'tcx>(
 369                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 370                         ty: Ty<'tcx>,
 371                     ) -> bool {
 372                         ty.builtin_deref(true)
 373                             .map(
 374                                 |ty::TypeAndMut {
 375                                      ty: pointee_ty,
 376                                      mutbl: _,
 377                                  }| has_ptr_meta(fx.tcx, pointee_ty),
 378                             )
 379                             .unwrap_or(false)
 380                     }
 381
 382                     if is_fat_ptr(fx, from_ty) {
 383                         if is_fat_ptr(fx, to_ty) {
 384                             // fat-ptr -> fat-ptr
 385                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 386                         } else {
 387                             // fat-ptr -> thin-ptr
 388                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 389                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 390                         }
 391                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind {
 392                         // enum -> discriminant value
 393                         assert!(adt_def.is_enum());
 394                         match to_ty.kind {
 395                             ty::Uint(_) | ty::Int(_) => {}
 396                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 397                         }
 398
 399                         let discr = crate::discriminant::codegen_get_discriminant(
 400                             fx,
 401                             operand,
 402                             fx.layout_of(to_ty),
 403                         );
 404                         lval.write_cvalue(fx, discr);
 405                     } else {
 406                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 407                         let from = operand.load_scalar(fx);
 408
 409                         let res = clif_int_or_float_cast(
 410                             fx,
 411                             from,
 412                             type_sign(from_ty),
 413                             to_clif_ty,
 414                             type_sign(to_ty),
 415                         );
 416                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 417                     }
 418                 }
 419                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
 420                     let operand = trans_operand(fx, operand);
 421                     match operand.layout().ty.kind {
 422                         ty::Closure(def_id, substs) => {
 423                             let instance = Instance::resolve_closure(
 424                                 fx.tcx,
 425                                 def_id,
 426                                 substs,
 427                                 ty::ClosureKind::FnOnce,
 428                             );
 429                             let func_ref = fx.get_function_ref(instance);
 430                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 431                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 432                         }
 433                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 434                     }
 435                 }
 436                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
 437                     let operand = trans_operand(fx, operand);
 438                     operand.unsize_value(fx, lval);
 439                 }
 440                 Rvalue::Discriminant(place) => {
 441                     let place = trans_place(fx, place);
 442                     let value = place.to_cvalue(fx);
 443                     let discr =
 444                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 445                     lval.write_cvalue(fx, discr);
 446                 }
 447                 Rvalue::Repeat(operand, times) => {
 448                     let operand = trans_operand(fx, operand);
 449                     for i in 0..*times {
 450                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 451                         let to = lval.place_index(fx, index);
 452                         to.write_cvalue(fx, operand);
 453                     }
 454                 }
 455                 Rvalue::Len(place) => {
 456                     let place = trans_place(fx, place);
 457                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 458                     let len = codegen_array_len(fx, place);
 459                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 460                 }
 461                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 462                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 463
 464                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 465                     let layout = fx.layout_of(content_ty);
 466                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 467                     let llalign = fx
 468                         .bcx
 469                         .ins()
 470                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 471                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 472
 473                     // Allocate space:
 474                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 475                         Ok(id) => id,
 476                         Err(s) => {
 477                             fx.tcx
 478                                 .sess
 479                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 480                         }
 481                     };
 482                     let instance = ty::Instance::mono(fx.tcx, def_id);
 483                     let func_ref = fx.get_function_ref(instance);
 484                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 485                     let ptr = fx.bcx.inst_results(call)[0];
 486                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 487                 }
 488                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 489                     assert!(lval
 490                         .layout()
 491                         .ty
 492                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 493                     let ty_size = fx.layout_of(ty).size.bytes();
 494                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size.into());
 495                     lval.write_cvalue(fx, val);
 496                 }
 497                 Rvalue::Aggregate(kind, operands) => match **kind {
 498                     AggregateKind::Array(_ty) => {
 499                         for (i, operand) in operands.into_iter().enumerate() {
 500                             let operand = trans_operand(fx, operand);
 501                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 502                             let to = lval.place_index(fx, index);
 503                             to.write_cvalue(fx, operand);
 504                         }
 505                     }
 506                     _ => unreachable!("shouldn't exist at trans {:?}", to_place_and_rval.1),
 507                 },
 508             }
 509         }
 510         StatementKind::StorageLive(_)
 511         | StatementKind::StorageDead(_)
 512         | StatementKind::Nop
 513         | StatementKind::FakeRead(..)
 514         | StatementKind::Retag { .. }
 515         | StatementKind::AscribeUserType(..) => {}
 516
 517         StatementKind::InlineAsm(asm) => {
 518             use syntax::ast::Name;
 519             let InlineAsm {
 520                 asm,
 521                 outputs: _,
 522                 inputs: _,
 523             } = &**asm;
 524             let rustc::hir::InlineAsmInner {
 525                 asm: asm_code, // Name
 526                 outputs,       // Vec<Name>
 527                 inputs,        // Vec<Name>
 528                 clobbers,      // Vec<Name>
 529                 volatile,      // bool
 530                 alignstack,    // bool
 531                 dialect: _,    // syntax::ast::AsmDialect
 532                 asm_str_style: _,
 533             } = asm;
 534             match &*asm_code.as_str() {
 535                 "" => {
 536                     assert_eq!(inputs, &[Name::intern("r")]);
 537                     assert!(outputs.is_empty(), "{:?}", outputs);
 538
 539                     // Black box
 540                 }
 541                 "cpuid" | "cpuid\n" => {
 542                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 543
 544                     assert_eq!(outputs.len(), 4);
 545                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 546                         .iter()
 547                         .enumerate()
 548                     {
 549                         assert_eq!(&outputs[i].constraint.as_str(), c);
 550                         assert!(!outputs[i].is_rw);
 551                         assert!(!outputs[i].is_indirect);
 552                     }
 553
 554                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 555
 556                     assert!(!volatile);
 557                     assert!(!alignstack);
 558
 559                     crate::trap::trap_unimplemented(
 560                         fx,
 561                         "__cpuid_count arch intrinsic is not supported",
 562                     );
 563                 }
 564                 "xgetbv" => {
 565                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 566
 567                     assert_eq!(outputs.len(), 2);
 568                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 569                         assert_eq!(&outputs[i].constraint.as_str(), c);
 570                         assert!(!outputs[i].is_rw);
 571                         assert!(!outputs[i].is_indirect);
 572                     }
 573
 574                     assert_eq!(clobbers, &[]);
 575
 576                     assert!(!volatile);
 577                     assert!(!alignstack);
 578
 579                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 580                 }
 581                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__rust_probestack" => {
 582                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 583                 }
 584                 _ => unimpl!("Inline assembly is not supported"),
 585             }
 586         }
 587     }
 588 }
 589
 590 fn codegen_array_len<'tcx>(
 591     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 592     place: CPlace<'tcx>,
 593 ) -> Value {
 594     match place.layout().ty.kind {
 595         ty::Array(_elem_ty, len) => {
 596             let len = crate::constant::force_eval_const(fx, len)
 597                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 598             fx.bcx.ins().iconst(fx.pointer_type, len)
 599         }
 600         ty::Slice(_elem_ty) => place
 601             .to_addr_maybe_unsized(fx)
 602             .1
 603             .expect("Length metadata for slice place"),
 604         _ => bug!("Rvalue::Len({:?})", place),
 605     }
 606 }
 607
 608 pub fn trans_place<'tcx>(
 609     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 610     place: &Place<'tcx>,
 611 ) -> CPlace<'tcx> {
 612     let mut cplace = match &place.base {
 613         PlaceBase::Local(local) => fx.get_local_place(*local),
 614         PlaceBase::Static(static_) => match static_.kind {
 615             StaticKind::Static => {
 616                 crate::constant::codegen_static_ref(fx, static_.def_id, static_.ty)
 617             }
 618             StaticKind::Promoted(promoted, substs) => {
 619                 let instance = Instance::new(static_.def_id, fx.monomorphize(&substs));
 620                 crate::constant::trans_promoted(fx, instance, promoted, static_.ty)
 621             }
 622         },
 623     };
 624
 625     for elem in &*place.projection {
 626         match *elem {
 627             PlaceElem::Deref => {
 628                 cplace = cplace.place_deref(fx);
 629             }
 630             PlaceElem::Field(field, _ty) => {
 631                 cplace = cplace.place_field(fx, field);
 632             }
 633             PlaceElem::Index(local) => {
 634                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 635                 cplace = cplace.place_index(fx, index);
 636             }
 637             PlaceElem::ConstantIndex {
 638                 offset,
 639                 min_length: _,
 640                 from_end,
 641             } => {
 642                 let index = if !from_end {
 643                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 644                 } else {
 645                     let len = codegen_array_len(fx, cplace);
 646                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 647                 };
 648                 cplace = cplace.place_index(fx, index);
 649             }
 650             PlaceElem::Subslice { from, to, from_end } => {
 651                 // These indices are generated by slice patterns.
 652                 // slice[from:-to] in Python terms.
 653
 654                 match cplace.layout().ty.kind {
 655                     ty::Array(elem_ty, len) => {
 656                         let elem_layout = fx.layout_of(elem_ty);
 657                         let ptr = cplace.to_addr(fx);
 658                         let len = crate::constant::force_eval_const(fx, len)
 659                             .eval_usize(fx.tcx, ParamEnv::reveal_all());
 660                         cplace = CPlace::for_addr(
 661                             fx.bcx
 662                                 .ins()
 663                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 664                             fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
 665                         );
 666                     }
 667                     ty::Slice(elem_ty) => {
 668                         assert!(from_end, "slice subslices should be `from_end`");
 669                         let elem_layout = fx.layout_of(elem_ty);
 670                         let (ptr, len) = cplace.to_addr_maybe_unsized(fx);
 671                         let len = len.unwrap();
 672                         cplace = CPlace::for_addr_with_extra(
 673                             fx.bcx
 674                                 .ins()
 675                                 .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 676                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 677                             cplace.layout(),
 678                         );
 679                     }
 680                     _ => unreachable!(),
 681                 }
 682             }
 683             PlaceElem::Downcast(_adt_def, variant) => {
 684                 cplace = cplace.downcast_variant(fx, variant);
 685             }
 686         }
 687     }
 688
 689     cplace
 690 }
 691
 692 pub fn trans_operand<'tcx>(
 693     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 694     operand: &Operand<'tcx>,
 695 ) -> CValue<'tcx> {
 696     match operand {
 697         Operand::Move(place) | Operand::Copy(place) => {
 698             let cplace = trans_place(fx, place);
 699             cplace.to_cvalue(fx)
 700         }
 701         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 702     }
 703 }