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