src/base.rs

   1 use rustc::ty::adjustment::PointerCast;
   2
   3 use crate::prelude::*;
   4
   5 pub fn trans_fn<'a, 'clif, 'tcx: 'a, 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     // Check fn sig for u128 and i128 and replace those functions with a trap.
  15     {
  16         // FIXME implement u128 and i128 support
  17
  18         // Check sig for u128 and i128
  19         let fn_sig = tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), &instance.fn_sig(tcx));
  20
  21         struct UI128Visitor<'tcx>(TyCtxt<'tcx>, bool);
  22
  23         impl<'tcx> rustc::ty::fold::TypeVisitor<'tcx> for UI128Visitor<'tcx> {
  24             fn visit_ty(&mut self, t: Ty<'tcx>) -> bool {
  25                 if t.sty == self.0.types.u128.sty || t.sty == self.0.types.i128.sty {
  26                     self.1 = true;
  27                     return false; // stop visiting
  28                 }
  29
  30                 t.super_visit_with(self)
  31             }
  32         }
  33
  34         let mut visitor = UI128Visitor(tcx, false);
  35         fn_sig.visit_with(&mut visitor);
  36
  37         //If found replace function with a trap.
  38         if visitor.1 {
  39             tcx.sess.warn("u128 and i128 are not yet supported. \
  40             Functions using these as args will be replaced with a trap.");
  41
  42             // Declare function with fake signature
  43             let sig = Signature {
  44                 params: vec![AbiParam::new(types::INVALID)],
  45                 returns: vec![],
  46                 call_conv: CallConv::Fast,
  47             };
  48             let name = tcx.symbol_name(instance).as_str();
  49             let func_id = cx.module.declare_function(&*name, linkage, &sig).unwrap();
  50
  51             // Create trapping function
  52             let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
  53             let mut func_ctx = FunctionBuilderContext::new();
  54             let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  55             let start_ebb = bcx.create_ebb();
  56             bcx.append_ebb_params_for_function_params(start_ebb);
  57             bcx.switch_to_block(start_ebb);
  58
  59             let mut fx = FunctionCx {
  60                 tcx,
  61                 module: cx.module,
  62                 pointer_type: pointer_ty(tcx),
  63
  64                 instance,
  65                 mir,
  66
  67                 bcx,
  68                 ebb_map: HashMap::new(),
  69                 local_map: HashMap::new(),
  70
  71                 clif_comments: crate::pretty_clif::CommentWriter::new(tcx, instance),
  72                 constants: &mut cx.ccx,
  73                 caches: &mut cx.caches,
  74                 source_info_set: indexmap::IndexSet::new(),
  75             };
  76
  77             crate::trap::trap_unreachable(&mut fx, "[unimplemented] Called function with u128 or i128 as argument.");
  78             fx.bcx.seal_all_blocks();
  79             fx.bcx.finalize();
  80
  81             // Define function
  82             cx.caches.context.func = func;
  83             cx.module
  84                 .define_function(func_id, &mut cx.caches.context)
  85                 .unwrap();
  86             cx.caches.context.clear();
  87             return;
  88         }
  89     }
  90
  91     // Declare function
  92     let (name, sig) = get_function_name_and_sig(tcx, instance, false);
  93     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  94     let mut debug_context = cx
  95         .debug_context
  96         .as_mut()
  97         .map(|debug_context| FunctionDebugContext::new(tcx, debug_context, mir, &name, &sig));
  98
  99     // Make FunctionBuilder
 100     let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
 101     let mut func_ctx = FunctionBuilderContext::new();
 102     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
 103
 104     // Predefine ebb's
 105     let start_ebb = bcx.create_ebb();
 106     let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
 107     for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
 108         ebb_map.insert(bb, bcx.create_ebb());
 109     }
 110
 111     // Make FunctionCx
 112     let pointer_type = cx.module.target_config().pointer_type();
 113     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
 114
 115     let mut fx = FunctionCx {
 116         tcx,
 117         module: cx.module,
 118         pointer_type,
 119
 120         instance,
 121         mir,
 122
 123         bcx,
 124         ebb_map,
 125         local_map: HashMap::new(),
 126
 127         clif_comments,
 128         constants: &mut cx.ccx,
 129         caches: &mut cx.caches,
 130         source_info_set: indexmap::IndexSet::new(),
 131     };
 132
 133     with_unimpl_span(fx.mir.span, || {
 134         crate::abi::codegen_fn_prelude(&mut fx, start_ebb);
 135         codegen_fn_content(&mut fx);
 136     });
 137
 138     // Recover all necessary data from fx, before accessing func will prevent future access to it.
 139     let instance = fx.instance;
 140     let clif_comments = fx.clif_comments;
 141     let source_info_set = fx.source_info_set;
 142
 143     #[cfg(debug_assertions)]
 144     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &func, &clif_comments, None);
 145
 146     // Verify function
 147     verify_func(tcx, &clif_comments, &func);
 148
 149     // Define function
 150     let context = &mut cx.caches.context;
 151     context.func = func;
 152     cx.module
 153         .define_function(func_id, context)
 154         .unwrap();
 155
 156     let value_ranges = context.build_value_labels_ranges(cx.module.isa()).expect("value location ranges");
 157
 158     // Write optimized function to file for debugging
 159     #[cfg(debug_assertions)]
 160     crate::pretty_clif::write_clif_file(cx.tcx, "opt", instance, &context.func, &clif_comments, Some(&value_ranges));
 161
 162     // Define debuginfo for function
 163     let isa = cx.module.isa();
 164     debug_context
 165         .as_mut()
 166         .map(|x| x.define(tcx, context, isa, &source_info_set));
 167
 168     // Clear context to make it usable for the next function
 169     context.clear();
 170 }
 171
 172 fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 173     let flags = settings::Flags::new(settings::builder());
 174     match ::cranelift::codegen::verify_function(&func, &flags) {
 175         Ok(_) => {}
 176         Err(err) => {
 177             tcx.sess.err(&format!("{:?}", err));
 178             let pretty_error = ::cranelift::codegen::print_errors::pretty_verifier_error(
 179                 &func,
 180                 None,
 181                 Some(Box::new(writer)),
 182                 err,
 183             );
 184             tcx.sess
 185                 .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 186         }
 187     }
 188 }
 189
 190 fn codegen_fn_content<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx, impl Backend>) {
 191     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 192         if bb_data.is_cleanup {
 193             // Unwinding after panicking is not supported
 194             continue;
 195         }
 196
 197         let ebb = fx.get_ebb(bb);
 198         fx.bcx.switch_to_block(ebb);
 199
 200         fx.bcx.ins().nop();
 201         for stmt in &bb_data.statements {
 202             fx.set_debug_loc(stmt.source_info);
 203             trans_stmt(fx, ebb, stmt);
 204         }
 205
 206         #[cfg(debug_assertions)]
 207         {
 208             let mut terminator_head = "\n".to_string();
 209             bb_data
 210                 .terminator()
 211                 .kind
 212                 .fmt_head(&mut terminator_head)
 213                 .unwrap();
 214             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 215             fx.add_comment(inst, terminator_head);
 216         }
 217
 218         fx.set_debug_loc(bb_data.terminator().source_info);
 219
 220         match &bb_data.terminator().kind {
 221             TerminatorKind::Goto { target } => {
 222                 let ebb = fx.get_ebb(*target);
 223                 fx.bcx.ins().jump(ebb, &[]);
 224             }
 225             TerminatorKind::Return => {
 226                 crate::abi::codegen_return(fx);
 227             }
 228             TerminatorKind::Assert {
 229                 cond,
 230                 expected,
 231                 msg,
 232                 target,
 233                 cleanup: _,
 234             } => {
 235                 let cond = trans_operand(fx, cond).load_scalar(fx);
 236                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 237                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 238                 let target = fx.get_ebb(*target);
 239                 if *expected {
 240                     fx.bcx.ins().brnz(cond, target, &[]);
 241                 } else {
 242                     fx.bcx.ins().brz(cond, target, &[]);
 243                 };
 244                 trap_panic(fx, format!("[panic] Assert {:?} failed.", msg));
 245             }
 246
 247             TerminatorKind::SwitchInt {
 248                 discr,
 249                 switch_ty: _,
 250                 values,
 251                 targets,
 252             } => {
 253                 let discr = trans_operand(fx, discr).load_scalar(fx);
 254                 let mut switch = ::cranelift::frontend::Switch::new();
 255                 for (i, value) in values.iter().enumerate() {
 256                     let ebb = fx.get_ebb(targets[i]);
 257                     switch.set_entry(*value as u64, ebb);
 258                 }
 259                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 260                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 261             }
 262             TerminatorKind::Call {
 263                 func,
 264                 args,
 265                 destination,
 266                 cleanup: _,
 267                 from_hir_call: _,
 268             } => {
 269                 crate::abi::codegen_terminator_call(fx, func, args, destination);
 270             }
 271             TerminatorKind::Resume | TerminatorKind::Abort => {
 272                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 273             }
 274             TerminatorKind::Unreachable => {
 275                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 276             }
 277             TerminatorKind::Yield { .. }
 278             | TerminatorKind::FalseEdges { .. }
 279             | TerminatorKind::FalseUnwind { .. }
 280             | TerminatorKind::DropAndReplace { .. }
 281             | TerminatorKind::GeneratorDrop => {
 282                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 283             }
 284             TerminatorKind::Drop {
 285                 location,
 286                 target,
 287                 unwind: _,
 288             } => {
 289                 let ty = location.ty(fx.mir, fx.tcx).ty;
 290                 let ty = fx.monomorphize(&ty);
 291                 let drop_fn = Instance::resolve_drop_in_place(fx.tcx, ty);
 292
 293                 if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
 294                     // we don't actually need to drop anything
 295                 } else {
 296                     let drop_place = trans_place(fx, location);
 297                     let drop_fn_ty = drop_fn.ty(fx.tcx);
 298                     match ty.sty {
 299                         ty::Dynamic(..) => {
 300                             crate::abi::codegen_drop(fx, drop_place, drop_fn_ty);
 301                         }
 302                         _ => {
 303                             let arg_place = CPlace::new_stack_slot(
 304                                 fx,
 305                                 fx.tcx.mk_ref(
 306                                     &ty::RegionKind::ReErased,
 307                                     TypeAndMut {
 308                                         ty,
 309                                         mutbl: crate::rustc::hir::Mutability::MutMutable,
 310                                     },
 311                                 ),
 312                             );
 313                             drop_place.write_place_ref(fx, arg_place);
 314                             let arg_value = arg_place.to_cvalue(fx);
 315                             crate::abi::codegen_call_inner(
 316                                 fx,
 317                                 None,
 318                                 drop_fn_ty,
 319                                 vec![arg_value],
 320                                 None,
 321                             );
 322                         }
 323                     }
 324                 }
 325
 326                 let target_ebb = fx.get_ebb(*target);
 327                 fx.bcx.ins().jump(target_ebb, &[]);
 328             }
 329         };
 330     }
 331
 332     fx.bcx.seal_all_blocks();
 333     fx.bcx.finalize();
 334 }
 335
 336 fn trans_stmt<'a, 'tcx: 'a>(
 337     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 338     cur_ebb: Ebb,
 339     stmt: &Statement<'tcx>,
 340 ) {
 341     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 342
 343     fx.set_debug_loc(stmt.source_info);
 344
 345     #[cfg(debug_assertions)]
 346     match &stmt.kind {
 347         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 348         _ => {
 349             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 350             fx.add_comment(inst, format!("{:?}", stmt));
 351         }
 352     }
 353
 354     match &stmt.kind {
 355         StatementKind::SetDiscriminant {
 356             place,
 357             variant_index,
 358         } => {
 359             let place = trans_place(fx, place);
 360             let layout = place.layout();
 361             if layout.for_variant(&*fx, *variant_index).abi == layout::Abi::Uninhabited {
 362                 return;
 363             }
 364             match layout.variants {
 365                 layout::Variants::Single { index } => {
 366                     assert_eq!(index, *variant_index);
 367                 }
 368                 layout::Variants::Multiple {
 369                     discr: _,
 370                     discr_index,
 371                     discr_kind: layout::DiscriminantKind::Tag,
 372                     variants: _,
 373                 } => {
 374                     let ptr = place.place_field(fx, mir::Field::new(discr_index));
 375                     let to = layout
 376                         .ty
 377                         .ty_adt_def()
 378                         .unwrap()
 379                         .discriminant_for_variant(fx.tcx, *variant_index)
 380                         .val;
 381                     let discr = CValue::const_val(fx, ptr.layout().ty, to as u64 as i64);
 382                     ptr.write_cvalue(fx, discr);
 383                 }
 384                 layout::Variants::Multiple {
 385                     discr: _,
 386                     discr_index,
 387                     discr_kind: layout::DiscriminantKind::Niche {
 388                         dataful_variant,
 389                         ref niche_variants,
 390                         niche_start,
 391                     },
 392                     variants: _,
 393                 } => {
 394                     if *variant_index != dataful_variant {
 395                         let niche = place.place_field(fx, mir::Field::new(discr_index));
 396                         //let niche_llty = niche.layout.immediate_llvm_type(bx.cx);
 397                         let niche_value =
 398                             ((variant_index.as_u32() - niche_variants.start().as_u32()) as u128)
 399                                 .wrapping_add(niche_start);
 400                         // FIXME(eddyb) Check the actual primitive type here.
 401                         let niche_llval = if niche_value == 0 {
 402                             CValue::const_val(fx, niche.layout().ty, 0)
 403                         } else {
 404                             CValue::const_val(fx, niche.layout().ty, niche_value as u64 as i64)
 405                         };
 406                         niche.write_cvalue(fx, niche_llval);
 407                     }
 408                 }
 409             }
 410         }
 411         StatementKind::Assign(to_place, rval) => {
 412             let lval = trans_place(fx, to_place);
 413             let dest_layout = lval.layout();
 414             match &**rval {
 415                 Rvalue::Use(operand) => {
 416                     let val = trans_operand(fx, operand);
 417                     lval.write_cvalue(fx, val);
 418                 }
 419                 Rvalue::Ref(_, _, place) => {
 420                     let place = trans_place(fx, place);
 421                     place.write_place_ref(fx, lval);
 422                 }
 423                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 424                     let ty = fx.monomorphize(&lhs.ty(fx.mir, fx.tcx));
 425                     let lhs = trans_operand(fx, lhs);
 426                     let rhs = trans_operand(fx, rhs);
 427
 428                     let res = match ty.sty {
 429                         ty::Bool => trans_bool_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 430                         ty::Uint(_) => {
 431                             trans_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, false)
 432                         }
 433                         ty::Int(_) => {
 434                             trans_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, true)
 435                         }
 436                         ty::Float(_) => trans_float_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 437                         ty::Char => trans_char_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 438                         ty::RawPtr(..) => trans_ptr_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 439                         ty::FnPtr(..) => trans_ptr_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 440                         _ => unimplemented!("binop {:?} for {:?}", bin_op, ty),
 441                     };
 442                     lval.write_cvalue(fx, res);
 443                 }
 444                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 445                     let ty = fx.monomorphize(&lhs.ty(fx.mir, fx.tcx));
 446                     let lhs = trans_operand(fx, lhs);
 447                     let rhs = trans_operand(fx, rhs);
 448
 449                     let res = match ty.sty {
 450                         ty::Uint(_) => {
 451                             trans_checked_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, false)
 452                         }
 453                         ty::Int(_) => {
 454                             trans_checked_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, true)
 455                         }
 456                         _ => unimplemented!("checked binop {:?} for {:?}", bin_op, ty),
 457                     };
 458                     lval.write_cvalue(fx, res);
 459                 }
 460                 Rvalue::UnaryOp(un_op, operand) => {
 461                     let operand = trans_operand(fx, operand);
 462                     let layout = operand.layout();
 463                     let val = operand.load_scalar(fx);
 464                     let res = match un_op {
 465                         UnOp::Not => {
 466                             match layout.ty.sty {
 467                                 ty::Bool => {
 468                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 469                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 470                                     fx.bcx.ins().bint(types::I8, res)
 471                                 }
 472                                 ty::Uint(_) | ty::Int(_) => fx.bcx.ins().bnot(val),
 473                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 474                             }
 475                         }
 476                         UnOp::Neg => match layout.ty.sty {
 477                             ty::Int(_) => {
 478                                 let clif_ty = fx.clif_type(layout.ty).unwrap();
 479                                 let zero = fx.bcx.ins().iconst(clif_ty, 0);
 480                                 fx.bcx.ins().isub(zero, val)
 481                             }
 482                             ty::Float(_) => fx.bcx.ins().fneg(val),
 483                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 484                         },
 485                     };
 486                     lval.write_cvalue(fx, CValue::by_val(res, layout));
 487                 }
 488                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 489                     let layout = fx.layout_of(ty);
 490                     match fx
 491                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 492                         .sty
 493                     {
 494                         ty::FnDef(def_id, substs) => {
 495                             let func_ref = fx.get_function_ref(
 496                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 497                                     .unwrap(),
 498                             );
 499                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 500                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 501                         }
 502                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 503                     }
 504                 }
 505                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 506                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty) => {
 507                     let operand = trans_operand(fx, operand);
 508                     let layout = fx.layout_of(ty);
 509                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 510                 }
 511                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 512                     let operand = trans_operand(fx, operand);
 513                     let from_ty = operand.layout().ty;
 514
 515                     fn is_fat_ptr<'a, 'tcx: 'a>(fx: &FunctionCx<'a, 'tcx, impl Backend>, ty: Ty<'tcx>) -> bool {
 516                         ty
 517                             .builtin_deref(true)
 518                             .map(|ty::TypeAndMut {ty: pointee_ty, mutbl: _ }| fx.layout_of(pointee_ty).is_unsized())
 519                             .unwrap_or(false)
 520                     }
 521
 522                     if is_fat_ptr(fx, from_ty) {
 523                         if is_fat_ptr(fx, to_ty) {
 524                             // fat-ptr -> fat-ptr
 525                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 526                         } else {
 527                             // fat-ptr -> thin-ptr
 528                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 529                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 530                         }
 531                     } else if let ty::Adt(adt_def, _substs) = from_ty.sty {
 532                         // enum -> discriminant value
 533                         assert!(adt_def.is_enum());
 534                         match to_ty.sty {
 535                             ty::Uint(_) | ty::Int(_) => {},
 536                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 537                         }
 538
 539                         // FIXME avoid forcing to stack
 540                         let place =
 541                             CPlace::for_addr(operand.force_stack(fx), operand.layout());
 542                         let discr = trans_get_discriminant(fx, place, fx.layout_of(to_ty));
 543                         lval.write_cvalue(fx, discr);
 544                     } else {
 545                         let from_clif_ty = fx.clif_type(from_ty).unwrap();
 546                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 547                         let from = operand.load_scalar(fx);
 548
 549                         let signed = match from_ty.sty {
 550                             ty::Ref(..) | ty::RawPtr(..) | ty::FnPtr(..) | ty::Char | ty::Uint(..) | ty::Bool => false,
 551                             ty::Int(..) => true,
 552                             ty::Float(..) => false, // `signed` is unused for floats
 553                             _ => panic!("{}", from_ty),
 554                         };
 555
 556                         let res = if from_clif_ty.is_int() && to_clif_ty.is_int() {
 557                             // int-like -> int-like
 558                             crate::common::clif_intcast(
 559                                 fx,
 560                                 from,
 561                                 to_clif_ty,
 562                                 signed,
 563                             )
 564                         } else if from_clif_ty.is_int() && to_clif_ty.is_float() {
 565                             // int-like -> float
 566                             if signed {
 567                                 fx.bcx.ins().fcvt_from_sint(to_clif_ty, from)
 568                             } else {
 569                                 fx.bcx.ins().fcvt_from_uint(to_clif_ty, from)
 570                             }
 571                         } else if from_clif_ty.is_float() && to_clif_ty.is_int() {
 572                             // float -> int-like
 573                             let from = operand.load_scalar(fx);
 574                             if signed {
 575                                 fx.bcx.ins().fcvt_to_sint_sat(to_clif_ty, from)
 576                             } else {
 577                                 fx.bcx.ins().fcvt_to_uint_sat(to_clif_ty, from)
 578                             }
 579                         } else if from_clif_ty.is_float() && to_clif_ty.is_float() {
 580                             // float -> float
 581                             match (from_clif_ty, to_clif_ty) {
 582                                 (types::F32, types::F64) => {
 583                                     fx.bcx.ins().fpromote(types::F64, from)
 584                                 }
 585                                 (types::F64, types::F32) => {
 586                                     fx.bcx.ins().fdemote(types::F32, from)
 587                                 }
 588                                 _ => from,
 589                             }
 590                         } else {
 591                             unimpl!("rval misc {:?} {:?}", from_ty, to_ty)
 592                         };
 593                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 594                     }
 595                 }
 596                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
 597                     let operand = trans_operand(fx, operand);
 598                     match operand.layout().ty.sty {
 599                         ty::Closure(def_id, substs) => {
 600                             let instance = Instance::resolve_closure(
 601                                 fx.tcx,
 602                                 def_id,
 603                                 substs,
 604                                 ty::ClosureKind::FnOnce,
 605                             );
 606                             let func_ref = fx.get_function_ref(instance);
 607                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 608                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 609                         }
 610                         _ => {
 611                             bug!("{} cannot be cast to a fn ptr", operand.layout().ty)
 612                         }
 613                     }
 614                 }
 615                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
 616                     let operand = trans_operand(fx, operand);
 617                     operand.unsize_value(fx, lval);
 618                 }
 619                 Rvalue::Discriminant(place) => {
 620                     let place = trans_place(fx, place);
 621                     let discr = trans_get_discriminant(fx, place, dest_layout);
 622                     lval.write_cvalue(fx, discr);
 623                 }
 624                 Rvalue::Repeat(operand, times) => {
 625                     let operand = trans_operand(fx, operand);
 626                     for i in 0..*times {
 627                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 628                         let to = lval.place_index(fx, index);
 629                         to.write_cvalue(fx, operand);
 630                     }
 631                 }
 632                 Rvalue::Len(place) => {
 633                     let place = trans_place(fx, place);
 634                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 635                     let len = codegen_array_len(fx, place);
 636                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 637                 }
 638                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 639                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 640
 641                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 642                     let layout = fx.layout_of(content_ty);
 643                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 644                     let llalign = fx
 645                         .bcx
 646                         .ins()
 647                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 648                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 649
 650                     // Allocate space:
 651                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 652                         Ok(id) => id,
 653                         Err(s) => {
 654                             fx.tcx
 655                                 .sess
 656                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 657                         }
 658                     };
 659                     let instance = ty::Instance::mono(fx.tcx, def_id);
 660                     let func_ref = fx.get_function_ref(instance);
 661                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 662                     let ptr = fx.bcx.inst_results(call)[0];
 663                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 664                 }
 665                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 666                     assert!(lval
 667                         .layout()
 668                         .ty
 669                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 670                     let ty_size = fx.layout_of(ty).size.bytes();
 671                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size as i64);
 672                     lval.write_cvalue(fx, val);
 673                 }
 674                 Rvalue::Aggregate(kind, operands) => match **kind {
 675                     AggregateKind::Array(_ty) => {
 676                         for (i, operand) in operands.into_iter().enumerate() {
 677                             let operand = trans_operand(fx, operand);
 678                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 679                             let to = lval.place_index(fx, index);
 680                             to.write_cvalue(fx, operand);
 681                         }
 682                     }
 683                     _ => unimpl!("shouldn't exist at trans {:?}", rval),
 684                 },
 685             }
 686         }
 687         StatementKind::StorageLive(_)
 688         | StatementKind::StorageDead(_)
 689         | StatementKind::Nop
 690         | StatementKind::FakeRead(..)
 691         | StatementKind::Retag { .. }
 692         | StatementKind::AscribeUserType(..) => {}
 693
 694         StatementKind::InlineAsm { .. } => unimpl!("Inline assembly is not supported"),
 695     }
 696 }
 697
 698 fn codegen_array_len<'a, 'tcx: 'a>(
 699     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 700     place: CPlace<'tcx>,
 701 ) -> Value {
 702     match place.layout().ty.sty {
 703         ty::Array(_elem_ty, len) => {
 704             let len = crate::constant::force_eval_const(fx, len).unwrap_usize(fx.tcx) as i64;
 705             fx.bcx.ins().iconst(fx.pointer_type, len)
 706         }
 707         ty::Slice(_elem_ty) => place
 708             .to_addr_maybe_unsized(fx)
 709             .1
 710             .expect("Length metadata for slice place"),
 711         _ => bug!("Rvalue::Len({:?})", place),
 712     }
 713 }
 714
 715 pub fn trans_get_discriminant<'a, 'tcx: 'a>(
 716     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 717     place: CPlace<'tcx>,
 718     dest_layout: TyLayout<'tcx>,
 719 ) -> CValue<'tcx> {
 720     let layout = place.layout();
 721
 722     if layout.abi == layout::Abi::Uninhabited {
 723         return trap_unreachable_ret_value(fx, dest_layout, "[panic] Tried to get discriminant for uninhabited type.");
 724     }
 725
 726     let (discr_scalar, discr_index, discr_kind) = match &layout.variants {
 727         layout::Variants::Single { index } => {
 728             let discr_val = layout
 729                 .ty
 730                 .ty_adt_def()
 731                 .map_or(index.as_u32() as u128, |def| {
 732                     def.discriminant_for_variant(fx.tcx, *index).val
 733                 });
 734             return CValue::const_val(fx, dest_layout.ty, discr_val as u64 as i64);
 735         }
 736         layout::Variants::Multiple { discr, discr_index, discr_kind, variants: _ } => {
 737             (discr, *discr_index, discr_kind)
 738         }
 739     };
 740
 741     let discr = place.place_field(fx, mir::Field::new(discr_index)).to_cvalue(fx);
 742     let discr_ty = discr.layout().ty;
 743     let lldiscr = discr.load_scalar(fx);
 744     match discr_kind {
 745         layout::DiscriminantKind::Tag => {
 746             let signed = match discr_scalar.value {
 747                 layout::Int(_, signed) => signed,
 748                 _ => false,
 749             };
 750             let val = clif_intcast(fx, lldiscr, fx.clif_type(dest_layout.ty).unwrap(), signed);
 751             return CValue::by_val(val, dest_layout);
 752         }
 753         layout::DiscriminantKind::Niche {
 754             dataful_variant,
 755             ref niche_variants,
 756             niche_start,
 757         } => {
 758             let niche_llty = fx.clif_type(discr_ty).unwrap();
 759             let dest_clif_ty = fx.clif_type(dest_layout.ty).unwrap();
 760             if niche_variants.start() == niche_variants.end() {
 761                 let b = fx
 762                     .bcx
 763                     .ins()
 764                     .icmp_imm(IntCC::Equal, lldiscr, *niche_start as u64 as i64);
 765                 let if_true = fx
 766                     .bcx
 767                     .ins()
 768                     .iconst(dest_clif_ty, niche_variants.start().as_u32() as i64);
 769                 let if_false = fx
 770                     .bcx
 771                     .ins()
 772                     .iconst(dest_clif_ty, dataful_variant.as_u32() as i64);
 773                 let val = fx.bcx.ins().select(b, if_true, if_false);
 774                 return CValue::by_val(val, dest_layout);
 775             } else {
 776                 // Rebase from niche values to discriminant values.
 777                 let delta = niche_start.wrapping_sub(niche_variants.start().as_u32() as u128);
 778                 let delta = fx.bcx.ins().iconst(niche_llty, delta as u64 as i64);
 779                 let lldiscr = fx.bcx.ins().isub(lldiscr, delta);
 780                 let b = fx.bcx.ins().icmp_imm(
 781                     IntCC::UnsignedLessThanOrEqual,
 782                     lldiscr,
 783                     niche_variants.end().as_u32() as i64,
 784                 );
 785                 let if_true =
 786                     clif_intcast(fx, lldiscr, fx.clif_type(dest_layout.ty).unwrap(), false);
 787                 let if_false = fx
 788                     .bcx
 789                     .ins()
 790                     .iconst(dest_clif_ty, dataful_variant.as_u32() as i64);
 791                 let val = fx.bcx.ins().select(b, if_true, if_false);
 792                 return CValue::by_val(val, dest_layout);
 793             }
 794         }
 795     }
 796 }
 797
 798 macro_rules! binop_match {
 799     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, bug) => {
 800         bug!("binop {} on {} lhs: {:?} rhs: {:?}", stringify!($var), $bug_fmt, $lhs, $rhs)
 801     };
 802     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, icmp($cc:ident)) => {{
 803         assert_eq!($fx.tcx.types.bool, $ret_ty);
 804         let ret_layout = $fx.layout_of($ret_ty);
 805
 806         let b = $fx.bcx.ins().icmp(IntCC::$cc, $lhs, $rhs);
 807         CValue::by_val($fx.bcx.ins().bint(types::I8, b), ret_layout)
 808     }};
 809     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, fcmp($cc:ident)) => {{
 810         assert_eq!($fx.tcx.types.bool, $ret_ty);
 811         let ret_layout = $fx.layout_of($ret_ty);
 812         let b = $fx.bcx.ins().fcmp(FloatCC::$cc, $lhs, $rhs);
 813         CValue::by_val($fx.bcx.ins().bint(types::I8, b), ret_layout)
 814     }};
 815     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, custom(|| $body:expr)) => {{
 816         $body
 817     }};
 818     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, $name:ident) => {{
 819         let ret_layout = $fx.layout_of($ret_ty);
 820         CValue::by_val($fx.bcx.ins().$name($lhs, $rhs), ret_layout)
 821     }};
 822     (
 823         $fx:expr, $bin_op:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, $bug_fmt:expr;
 824         $(
 825             $var:ident ($sign:pat) $name:tt $( ( $($next:tt)* ) )? ;
 826         )*
 827     ) => {{
 828         let lhs = $lhs.load_scalar($fx);
 829         let rhs = $rhs.load_scalar($fx);
 830         match ($bin_op, $signed) {
 831             $(
 832                 (BinOp::$var, $sign) => binop_match!(@single $fx, $bug_fmt, $var, $signed, lhs, rhs, $ret_ty, $name $( ( $($next)* ) )?),
 833             )*
 834         }
 835     }}
 836 }
 837
 838 fn trans_bool_binop<'a, 'tcx: 'a>(
 839     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 840     bin_op: BinOp,
 841     lhs: CValue<'tcx>,
 842     rhs: CValue<'tcx>,
 843     ty: Ty<'tcx>,
 844 ) -> CValue<'tcx> {
 845     let res = binop_match! {
 846         fx, bin_op, false, lhs, rhs, ty, "bool";
 847         Add (_) bug;
 848         Sub (_) bug;
 849         Mul (_) bug;
 850         Div (_) bug;
 851         Rem (_) bug;
 852         BitXor (_) bxor;
 853         BitAnd (_) band;
 854         BitOr (_) bor;
 855         Shl (_) bug;
 856         Shr (_) bug;
 857
 858         Eq (_) icmp(Equal);
 859         Lt (_) icmp(UnsignedLessThan);
 860         Le (_) icmp(UnsignedLessThanOrEqual);
 861         Ne (_) icmp(NotEqual);
 862         Ge (_) icmp(UnsignedGreaterThanOrEqual);
 863         Gt (_) icmp(UnsignedGreaterThan);
 864
 865         Offset (_) bug;
 866     };
 867
 868     res
 869 }
 870
 871 pub fn trans_int_binop<'a, 'tcx: 'a>(
 872     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 873     bin_op: BinOp,
 874     lhs: CValue<'tcx>,
 875     rhs: CValue<'tcx>,
 876     out_ty: Ty<'tcx>,
 877     signed: bool,
 878 ) -> CValue<'tcx> {
 879     if bin_op != BinOp::Shl && bin_op != BinOp::Shr {
 880         assert_eq!(
 881             lhs.layout().ty,
 882             rhs.layout().ty,
 883             "int binop requires lhs and rhs of same type"
 884         );
 885     }
 886     binop_match! {
 887         fx, bin_op, signed, lhs, rhs, out_ty, "int/uint";
 888         Add (_) iadd;
 889         Sub (_) isub;
 890         Mul (_) imul;
 891         Div (false) udiv;
 892         Div (true) sdiv;
 893         Rem (false) urem;
 894         Rem (true) srem;
 895         BitXor (_) bxor;
 896         BitAnd (_) band;
 897         BitOr (_) bor;
 898         Shl (_) ishl;
 899         Shr (false) ushr;
 900         Shr (true) sshr;
 901
 902         Eq (_) icmp(Equal);
 903         Lt (false) icmp(UnsignedLessThan);
 904         Lt (true) icmp(SignedLessThan);
 905         Le (false) icmp(UnsignedLessThanOrEqual);
 906         Le (true) icmp(SignedLessThanOrEqual);
 907         Ne (_) icmp(NotEqual);
 908         Ge (false) icmp(UnsignedGreaterThanOrEqual);
 909         Ge (true) icmp(SignedGreaterThanOrEqual);
 910         Gt (false) icmp(UnsignedGreaterThan);
 911         Gt (true) icmp(SignedGreaterThan);
 912
 913         Offset (_) bug;
 914     }
 915 }
 916
 917 pub fn trans_checked_int_binop<'a, 'tcx: 'a>(
 918     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 919     bin_op: BinOp,
 920     in_lhs: CValue<'tcx>,
 921     in_rhs: CValue<'tcx>,
 922     out_ty: Ty<'tcx>,
 923     signed: bool,
 924 ) -> CValue<'tcx> {
 925     if bin_op != BinOp::Shl && bin_op != BinOp::Shr {
 926         assert_eq!(
 927             in_lhs.layout().ty,
 928             in_rhs.layout().ty,
 929             "checked int binop requires lhs and rhs of same type"
 930         );
 931     }
 932
 933     let lhs = in_lhs.load_scalar(fx);
 934     let rhs = in_rhs.load_scalar(fx);
 935     let res = match bin_op {
 936         BinOp::Add => fx.bcx.ins().iadd(lhs, rhs),
 937         BinOp::Sub => fx.bcx.ins().isub(lhs, rhs),
 938         BinOp::Mul => fx.bcx.ins().imul(lhs, rhs),
 939         BinOp::Shl => fx.bcx.ins().ishl(lhs, rhs),
 940         BinOp::Shr => {
 941             if !signed {
 942                 fx.bcx.ins().ushr(lhs, rhs)
 943             } else {
 944                 fx.bcx.ins().sshr(lhs, rhs)
 945             }
 946         }
 947         _ => bug!(
 948             "binop {:?} on checked int/uint lhs: {:?} rhs: {:?}",
 949             bin_op,
 950             in_lhs,
 951             in_rhs
 952         ),
 953     };
 954
 955     // TODO: check for overflow
 956     let has_overflow = fx.bcx.ins().iconst(types::I8, 0);
 957
 958     let out_place = CPlace::new_stack_slot(fx, out_ty);
 959     let out_layout = out_place.layout();
 960     out_place.write_cvalue(fx, CValue::by_val_pair(res, has_overflow, out_layout));
 961
 962     out_place.to_cvalue(fx)
 963 }
 964
 965 fn trans_float_binop<'a, 'tcx: 'a>(
 966     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 967     bin_op: BinOp,
 968     lhs: CValue<'tcx>,
 969     rhs: CValue<'tcx>,
 970     ty: Ty<'tcx>,
 971 ) -> CValue<'tcx> {
 972     let res = binop_match! {
 973         fx, bin_op, false, lhs, rhs, ty, "float";
 974         Add (_) fadd;
 975         Sub (_) fsub;
 976         Mul (_) fmul;
 977         Div (_) fdiv;
 978         Rem (_) custom(|| {
 979             assert_eq!(lhs.layout().ty, ty);
 980             assert_eq!(rhs.layout().ty, ty);
 981             match ty.sty {
 982                 ty::Float(FloatTy::F32) => fx.easy_call("fmodf", &[lhs, rhs], ty),
 983                 ty::Float(FloatTy::F64) => fx.easy_call("fmod", &[lhs, rhs], ty),
 984                 _ => bug!(),
 985             }
 986         });
 987         BitXor (_) bxor;
 988         BitAnd (_) band;
 989         BitOr (_) bor;
 990         Shl (_) bug;
 991         Shr (_) bug;
 992
 993         Eq (_) fcmp(Equal);
 994         Lt (_) fcmp(LessThan);
 995         Le (_) fcmp(LessThanOrEqual);
 996         Ne (_) fcmp(NotEqual);
 997         Ge (_) fcmp(GreaterThanOrEqual);
 998         Gt (_) fcmp(GreaterThan);
 999
1000         Offset (_) bug;
1001     };
1002
1003     res
1004 }
1005
1006 fn trans_char_binop<'a, 'tcx: 'a>(
1007     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1008     bin_op: BinOp,
1009     lhs: CValue<'tcx>,
1010     rhs: CValue<'tcx>,
1011     ty: Ty<'tcx>,
1012 ) -> CValue<'tcx> {
1013     let res = binop_match! {
1014         fx, bin_op, false, lhs, rhs, ty, "char";
1015         Add (_) bug;
1016         Sub (_) bug;
1017         Mul (_) bug;
1018         Div (_) bug;
1019         Rem (_) bug;
1020         BitXor (_) bug;
1021         BitAnd (_) bug;
1022         BitOr (_) bug;
1023         Shl (_) bug;
1024         Shr (_) bug;
1025
1026         Eq (_) icmp(Equal);
1027         Lt (_) icmp(UnsignedLessThan);
1028         Le (_) icmp(UnsignedLessThanOrEqual);
1029         Ne (_) icmp(NotEqual);
1030         Ge (_) icmp(UnsignedGreaterThanOrEqual);
1031         Gt (_) icmp(UnsignedGreaterThan);
1032
1033         Offset (_) bug;
1034     };
1035
1036     res
1037 }
1038
1039 fn trans_ptr_binop<'a, 'tcx: 'a>(
1040     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1041     bin_op: BinOp,
1042     lhs: CValue<'tcx>,
1043     rhs: CValue<'tcx>,
1044     ret_ty: Ty<'tcx>,
1045 ) -> CValue<'tcx> {
1046     let not_fat = match lhs.layout().ty.sty {
1047         ty::RawPtr(TypeAndMut { ty, mutbl: _ }) => {
1048             ty.is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all())
1049         }
1050         ty::FnPtr(..) => true,
1051         _ => bug!("trans_ptr_binop on non ptr"),
1052     };
1053     if not_fat {
1054         if let BinOp::Offset = bin_op {
1055             let (base, offset) = (lhs, rhs.load_scalar(fx));
1056             let pointee_ty = base.layout().ty.builtin_deref(true).unwrap().ty;
1057             let pointee_size = fx.layout_of(pointee_ty).size.bytes();
1058             let ptr_diff = fx.bcx.ins().imul_imm(offset, pointee_size as i64);
1059             let base_val = base.load_scalar(fx);
1060             let res = fx.bcx.ins().iadd(base_val, ptr_diff);
1061             return CValue::by_val(res, base.layout());
1062         }
1063
1064         binop_match! {
1065             fx, bin_op, false, lhs, rhs, ret_ty, "ptr";
1066             Add (_) bug;
1067             Sub (_) bug;
1068             Mul (_) bug;
1069             Div (_) bug;
1070             Rem (_) bug;
1071             BitXor (_) bug;
1072             BitAnd (_) bug;
1073             BitOr (_) bug;
1074             Shl (_) bug;
1075             Shr (_) bug;
1076
1077             Eq (_) icmp(Equal);
1078             Lt (_) icmp(UnsignedLessThan);
1079             Le (_) icmp(UnsignedLessThanOrEqual);
1080             Ne (_) icmp(NotEqual);
1081             Ge (_) icmp(UnsignedGreaterThanOrEqual);
1082             Gt (_) icmp(UnsignedGreaterThan);
1083
1084             Offset (_) bug; // Handled above
1085         }
1086     } else {
1087         let (lhs_ptr, lhs_extra) = lhs.load_scalar_pair(fx);
1088         let (rhs_ptr, rhs_extra) = rhs.load_scalar_pair(fx);
1089         let res = match bin_op {
1090             BinOp::Eq => {
1091                 let ptr_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_ptr, rhs_ptr);
1092                 let extra_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_extra, rhs_extra);
1093                 fx.bcx.ins().band(ptr_eq, extra_eq)
1094             }
1095             BinOp::Ne => {
1096                 let ptr_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_ptr, rhs_ptr);
1097                 let extra_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_extra, rhs_extra);
1098                 fx.bcx.ins().bor(ptr_ne, extra_ne)
1099             }
1100             _ => unimplemented!(
1101                 "trans_ptr_binop({:?}, <fat ptr>, <fat ptr>) not implemented",
1102                 bin_op
1103             ),
1104         };
1105
1106         assert_eq!(fx.tcx.types.bool, ret_ty);
1107         let ret_layout = fx.layout_of(ret_ty);
1108         CValue::by_val(fx.bcx.ins().bint(types::I8, res), ret_layout)
1109     }
1110 }
1111
1112 pub fn trans_place<'a, 'tcx: 'a>(
1113     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1114     place: &Place<'tcx>,
1115 ) -> CPlace<'tcx> {
1116     match place {
1117         Place::Base(base) => match base {
1118             PlaceBase::Local(local) => fx.get_local_place(*local),
1119             PlaceBase::Static(static_) => match static_.kind {
1120                 StaticKind::Static(def_id) => {
1121                     crate::constant::codegen_static_ref(fx, def_id, static_.ty)
1122                 }
1123                 StaticKind::Promoted(promoted) => {
1124                     crate::constant::trans_promoted(fx, promoted, static_.ty)
1125                 }
1126             }
1127         }
1128         Place::Projection(projection) => {
1129             let base = trans_place(fx, &projection.base);
1130             match projection.elem {
1131                 ProjectionElem::Deref => base.place_deref(fx),
1132                 ProjectionElem::Field(field, _ty) => base.place_field(fx, field),
1133                 ProjectionElem::Index(local) => {
1134                     let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
1135                     base.place_index(fx, index)
1136                 }
1137                 ProjectionElem::ConstantIndex {
1138                     offset,
1139                     min_length: _,
1140                     from_end,
1141                 } => {
1142                     let index = if !from_end {
1143                         fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
1144                     } else {
1145                         let len = codegen_array_len(fx, base);
1146                         fx.bcx.ins().iadd_imm(len, -(offset as i64))
1147                     };
1148                     base.place_index(fx, index)
1149                 }
1150                 ProjectionElem::Subslice { from, to } => {
1151                     // These indices are generated by slice patterns.
1152                     // slice[from:-to] in Python terms.
1153
1154                     match base.layout().ty.sty {
1155                         ty::Array(elem_ty, len) => {
1156                             let elem_layout = fx.layout_of(elem_ty);
1157                             let ptr = base.to_addr(fx);
1158                             let len = crate::constant::force_eval_const(fx, len).unwrap_usize(fx.tcx);
1159                             CPlace::for_addr(
1160                                 fx.bcx.ins().iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
1161                                 fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
1162                             )
1163                         }
1164                         ty::Slice(elem_ty) => {
1165                             let elem_layout = fx.layout_of(elem_ty);
1166                             let (ptr, len) = base.to_addr_maybe_unsized(fx);
1167                             let len = len.unwrap();
1168                             CPlace::for_addr_with_extra(
1169                                 fx.bcx.ins().iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
1170                                 fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
1171                                 base.layout(),
1172                             )
1173                         }
1174                         _ => unreachable!(),
1175                     }
1176                 }
1177                 ProjectionElem::Downcast(_adt_def, variant) => base.downcast_variant(fx, variant),
1178             }
1179         }
1180     }
1181 }
1182
1183 pub fn trans_operand<'a, 'tcx>(
1184     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1185     operand: &Operand<'tcx>,
1186 ) -> CValue<'tcx> {
1187     match operand {
1188         Operand::Move(place) | Operand::Copy(place) => {
1189             let cplace = trans_place(fx, place);
1190             cplace.to_cvalue(fx)
1191         }
1192         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
1193     }
1194 }