src/base.rs

   1 use crate::prelude::*;
   2
   3 struct PrintOnPanic<F: Fn() -> String>(F);
   4 impl<F: Fn() -> String> Drop for PrintOnPanic<F> {
   5     fn drop(&mut self) {
   6         if ::std::thread::panicking() {
   7             println!("{}", (self.0)());
   8         }
   9     }
  10 }
  11
  12 pub fn trans_mono_item<'a, 'clif, 'tcx: 'a, B: Backend + 'static>(
  13     cx: &mut crate::CodegenCx<'a, 'clif, 'tcx, B>,
  14     mono_item: MonoItem<'tcx>,
  15     linkage: Linkage,
  16 ) {
  17     let tcx = cx.tcx;
  18     match mono_item {
  19         MonoItem::Fn(inst) => {
  20             let _inst_guard =
  21                 PrintOnPanic(|| format!("{:?} {}", inst, tcx.symbol_name(inst).as_str()));
  22             debug_assert!(!inst.substs.needs_infer());
  23             let _mir_guard = PrintOnPanic(|| {
  24                 match inst.def {
  25                     InstanceDef::Item(_)
  26                     | InstanceDef::DropGlue(_, _)
  27                     | InstanceDef::Virtual(_, _)
  28                         if inst.def_id().krate == LOCAL_CRATE =>
  29                     {
  30                         let mut mir = ::std::io::Cursor::new(Vec::new());
  31                         crate::rustc_mir::util::write_mir_pretty(
  32                             tcx,
  33                             Some(inst.def_id()),
  34                             &mut mir,
  35                         )
  36                         .unwrap();
  37                         String::from_utf8(mir.into_inner()).unwrap()
  38                     }
  39                     _ => {
  40                         // FIXME fix write_mir_pretty for these instances
  41                         format!("{:#?}", tcx.instance_mir(inst.def))
  42                     }
  43                 }
  44             });
  45
  46             trans_fn(cx, inst, linkage);
  47         }
  48         MonoItem::Static(def_id) => {
  49             crate::constant::codegen_static(&mut cx.ccx, def_id);
  50         }
  51         MonoItem::GlobalAsm(node_id) => tcx
  52             .sess
  53             .fatal(&format!("Unimplemented global asm mono item {:?}", node_id)),
  54     }
  55 }
  56
  57 fn trans_fn<'a, 'clif, 'tcx: 'a, B: Backend + 'static>(
  58     cx: &mut crate::CodegenCx<'a, 'clif, 'tcx, B>,
  59     instance: Instance<'tcx>,
  60     linkage: Linkage,
  61 ) {
  62     let tcx = cx.tcx;
  63
  64     // Step 1. Get mir
  65     let mir = tcx.instance_mir(instance.def);
  66
  67     // Step 2. Declare function
  68     let (name, sig) = get_function_name_and_sig(tcx, instance, false);
  69     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  70     let mut debug_context = cx
  71         .debug_context
  72         .as_mut()
  73         .map(|debug_context| FunctionDebugContext::new(tcx, debug_context, mir, &name, &sig));
  74
  75     // Step 3. Make FunctionBuilder
  76     let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
  77     let mut func_ctx = FunctionBuilderContext::new();
  78     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  79
  80     // Step 4. Predefine ebb's
  81     let start_ebb = bcx.create_ebb();
  82     let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
  83     for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
  84         ebb_map.insert(bb, bcx.create_ebb());
  85     }
  86
  87     // Step 5. Make FunctionCx
  88     let pointer_type = cx.module.target_config().pointer_type();
  89     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  90
  91     let mut fx = FunctionCx {
  92         tcx,
  93         module: cx.module,
  94         pointer_type,
  95
  96         instance,
  97         mir,
  98
  99         bcx,
 100         ebb_map,
 101         local_map: HashMap::new(),
 102
 103         clif_comments,
 104         constants: &mut cx.ccx,
 105         caches: &mut cx.caches,
 106         source_info_set: indexmap::IndexSet::new(),
 107     };
 108
 109     // Step 6. Codegen function
 110     with_unimpl_span(fx.mir.span, || {
 111         crate::abi::codegen_fn_prelude(&mut fx, start_ebb);
 112         codegen_fn_content(&mut fx);
 113     });
 114     let source_info_set = fx.source_info_set.clone();
 115
 116     // Step 7. Write function to file for debugging
 117     #[cfg(debug_assertions)]
 118     fx.write_clif_file();
 119
 120     // Step 8. Verify function
 121     verify_func(tcx, fx.clif_comments, &func);
 122
 123     // Step 9. Define function
 124     cx.caches.context.func = func;
 125     cx.module
 126         .define_function(func_id, &mut cx.caches.context)
 127         .unwrap();
 128
 129     // Step 10. Define debuginfo for function
 130     let context = &cx.caches.context;
 131     let isa = cx.module.isa();
 132     debug_context
 133         .as_mut()
 134         .map(|x| x.define(tcx, context, isa, &source_info_set));
 135
 136     // Step 11. Clear context to make it usable for the next function
 137     cx.caches.context.clear();
 138 }
 139
 140 fn verify_func(tcx: TyCtxt, writer: crate::pretty_clif::CommentWriter, func: &Function) {
 141     let flags = settings::Flags::new(settings::builder());
 142     match ::cranelift::codegen::verify_function(&func, &flags) {
 143         Ok(_) => {}
 144         Err(err) => {
 145             tcx.sess.err(&format!("{:?}", err));
 146             let pretty_error = ::cranelift::codegen::print_errors::pretty_verifier_error(
 147                 &func,
 148                 None,
 149                 Some(Box::new(&writer)),
 150                 err,
 151             );
 152             tcx.sess
 153                 .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 154         }
 155     }
 156 }
 157
 158 fn codegen_fn_content<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx, impl Backend>) {
 159     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 160         if bb_data.is_cleanup {
 161             // Unwinding after panicking is not supported
 162             continue;
 163         }
 164
 165         let ebb = fx.get_ebb(bb);
 166         fx.bcx.switch_to_block(ebb);
 167
 168         fx.bcx.ins().nop();
 169         for stmt in &bb_data.statements {
 170             fx.set_debug_loc(stmt.source_info);
 171             trans_stmt(fx, ebb, stmt);
 172         }
 173
 174         #[cfg(debug_assertions)]
 175         {
 176             let mut terminator_head = "\n".to_string();
 177             bb_data
 178                 .terminator()
 179                 .kind
 180                 .fmt_head(&mut terminator_head)
 181                 .unwrap();
 182             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 183             fx.add_comment(inst, terminator_head);
 184         }
 185
 186         fx.set_debug_loc(bb_data.terminator().source_info);
 187
 188         match &bb_data.terminator().kind {
 189             TerminatorKind::Goto { target } => {
 190                 let ebb = fx.get_ebb(*target);
 191                 fx.bcx.ins().jump(ebb, &[]);
 192             }
 193             TerminatorKind::Return => {
 194                 crate::abi::codegen_return(fx);
 195             }
 196             TerminatorKind::Assert {
 197                 cond,
 198                 expected,
 199                 msg: _,
 200                 target,
 201                 cleanup: _,
 202             } => {
 203                 let cond = trans_operand(fx, cond).load_scalar(fx);
 204                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 205                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 206                 let target = fx.get_ebb(*target);
 207                 if *expected {
 208                     fx.bcx.ins().brnz(cond, target, &[]);
 209                 } else {
 210                     fx.bcx.ins().brz(cond, target, &[]);
 211                 };
 212                 trap_panic(&mut fx.bcx);
 213             }
 214
 215             TerminatorKind::SwitchInt {
 216                 discr,
 217                 switch_ty: _,
 218                 values,
 219                 targets,
 220             } => {
 221                 let discr = trans_operand(fx, discr).load_scalar(fx);
 222                 let mut switch = ::cranelift::frontend::Switch::new();
 223                 for (i, value) in values.iter().enumerate() {
 224                     let ebb = fx.get_ebb(targets[i]);
 225                     switch.set_entry(*value as u64, ebb);
 226                 }
 227                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 228                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 229             }
 230             TerminatorKind::Call {
 231                 func,
 232                 args,
 233                 destination,
 234                 cleanup: _,
 235                 from_hir_call: _,
 236             } => {
 237                 crate::abi::codegen_terminator_call(fx, func, args, destination);
 238             }
 239             TerminatorKind::Resume | TerminatorKind::Abort | TerminatorKind::Unreachable => {
 240                 trap_unreachable(&mut fx.bcx);
 241             }
 242             TerminatorKind::Yield { .. }
 243             | TerminatorKind::FalseEdges { .. }
 244             | TerminatorKind::FalseUnwind { .. }
 245             | TerminatorKind::DropAndReplace { .. }
 246             | TerminatorKind::GeneratorDrop => {
 247                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 248             }
 249             TerminatorKind::Drop {
 250                 location,
 251                 target,
 252                 unwind: _,
 253             } => {
 254                 let ty = location.ty(fx.mir, fx.tcx).to_ty(fx.tcx);
 255                 let ty = fx.monomorphize(&ty);
 256                 let drop_fn = crate::rustc_mir::monomorphize::resolve_drop_in_place(fx.tcx, ty);
 257
 258                 if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
 259                     // we don't actually need to drop anything
 260                 } else {
 261                     let drop_place = trans_place(fx, location);
 262                     let drop_fn_ty = drop_fn.ty(fx.tcx);
 263                     match ty.sty {
 264                         ty::Dynamic(..) => {
 265                             crate::abi::codegen_drop(fx, drop_place, drop_fn_ty);
 266                         }
 267                         _ => {
 268                             let arg_place = CPlace::new_stack_slot(
 269                                 fx,
 270                                 fx.tcx.mk_ref(
 271                                     &ty::RegionKind::ReErased,
 272                                     TypeAndMut {
 273                                         ty,
 274                                         mutbl: crate::rustc::hir::Mutability::MutMutable,
 275                                     },
 276                                 ),
 277                             );
 278                             drop_place.write_place_ref(fx, arg_place);
 279                             let arg_value = arg_place.to_cvalue(fx);
 280                             crate::abi::codegen_call_inner(
 281                                 fx,
 282                                 None,
 283                                 drop_fn_ty,
 284                                 vec![arg_value],
 285                                 None,
 286                             );
 287                         }
 288                     }
 289                 }
 290
 291                 let target_ebb = fx.get_ebb(*target);
 292                 fx.bcx.ins().jump(target_ebb, &[]);
 293             }
 294         };
 295     }
 296
 297     fx.bcx.seal_all_blocks();
 298     fx.bcx.finalize();
 299 }
 300
 301 fn trans_stmt<'a, 'tcx: 'a>(
 302     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 303     cur_ebb: Ebb,
 304     stmt: &Statement<'tcx>,
 305 ) {
 306     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 307
 308     fx.set_debug_loc(stmt.source_info);
 309
 310     #[cfg(debug_assertions)]
 311     match &stmt.kind {
 312         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 313         _ => {
 314             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 315             fx.add_comment(inst, format!("{:?}", stmt));
 316         }
 317     }
 318
 319     match &stmt.kind {
 320         StatementKind::SetDiscriminant {
 321             place,
 322             variant_index,
 323         } => {
 324             let place = trans_place(fx, place);
 325             let layout = place.layout();
 326             if layout.for_variant(&*fx, *variant_index).abi == layout::Abi::Uninhabited {
 327                 return;
 328             }
 329             match layout.variants {
 330                 layout::Variants::Single { index } => {
 331                     assert_eq!(index, *variant_index);
 332                 }
 333                 layout::Variants::Tagged { .. } => {
 334                     let ptr = place.place_field(fx, mir::Field::new(0));
 335                     let to = layout
 336                         .ty
 337                         .ty_adt_def()
 338                         .unwrap()
 339                         .discriminant_for_variant(fx.tcx, *variant_index)
 340                         .val;
 341                     let discr = CValue::const_val(fx, ptr.layout().ty, to as u64 as i64);
 342                     ptr.write_cvalue(fx, discr);
 343                 }
 344                 layout::Variants::NicheFilling {
 345                     dataful_variant,
 346                     ref niche_variants,
 347                     niche_start,
 348                     ..
 349                 } => {
 350                     if *variant_index != dataful_variant {
 351                         let niche = place.place_field(fx, mir::Field::new(0));
 352                         //let niche_llty = niche.layout.immediate_llvm_type(bx.cx);
 353                         let niche_value =
 354                             ((variant_index.as_u32() - niche_variants.start().as_u32()) as u128)
 355                                 .wrapping_add(niche_start);
 356                         // FIXME(eddyb) Check the actual primitive type here.
 357                         let niche_llval = if niche_value == 0 {
 358                             CValue::const_val(fx, niche.layout().ty, 0)
 359                         } else {
 360                             CValue::const_val(fx, niche.layout().ty, niche_value as u64 as i64)
 361                         };
 362                         niche.write_cvalue(fx, niche_llval);
 363                     }
 364                 }
 365             }
 366         }
 367         StatementKind::Assign(to_place, rval) => {
 368             let lval = trans_place(fx, to_place);
 369             let dest_layout = lval.layout();
 370             match &**rval {
 371                 Rvalue::Use(operand) => {
 372                     let val = trans_operand(fx, operand);
 373                     lval.write_cvalue(fx, val);
 374                 }
 375                 Rvalue::Ref(_, _, place) => {
 376                     let place = trans_place(fx, place);
 377                     place.write_place_ref(fx, lval);
 378                 }
 379                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 380                     let ty = fx.monomorphize(&lhs.ty(fx.mir, fx.tcx));
 381                     let lhs = trans_operand(fx, lhs);
 382                     let rhs = trans_operand(fx, rhs);
 383
 384                     let res = match ty.sty {
 385                         ty::Bool => trans_bool_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 386                         ty::Uint(_) => {
 387                             trans_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, false)
 388                         }
 389                         ty::Int(_) => {
 390                             trans_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, true)
 391                         }
 392                         ty::Float(_) => trans_float_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 393                         ty::Char => trans_char_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 394                         ty::RawPtr(..) => trans_ptr_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 395                         ty::FnPtr(..) => trans_ptr_binop(fx, *bin_op, lhs, rhs, lval.layout().ty),
 396                         _ => unimplemented!("binop {:?} for {:?}", bin_op, ty),
 397                     };
 398                     lval.write_cvalue(fx, res);
 399                 }
 400                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 401                     let ty = fx.monomorphize(&lhs.ty(fx.mir, fx.tcx));
 402                     let lhs = trans_operand(fx, lhs);
 403                     let rhs = trans_operand(fx, rhs);
 404
 405                     let res = match ty.sty {
 406                         ty::Uint(_) => {
 407                             trans_checked_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, false)
 408                         }
 409                         ty::Int(_) => {
 410                             trans_checked_int_binop(fx, *bin_op, lhs, rhs, lval.layout().ty, true)
 411                         }
 412                         _ => unimplemented!("checked binop {:?} for {:?}", bin_op, ty),
 413                     };
 414                     lval.write_cvalue(fx, res);
 415                 }
 416                 Rvalue::UnaryOp(un_op, operand) => {
 417                     let operand = trans_operand(fx, operand);
 418                     let layout = operand.layout();
 419                     let val = operand.load_scalar(fx);
 420                     let res = match un_op {
 421                         UnOp::Not => {
 422                             match layout.ty.sty {
 423                                 ty::Bool => {
 424                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 425                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 426                                     fx.bcx.ins().bint(types::I8, res)
 427                                 }
 428                                 ty::Uint(_) | ty::Int(_) => fx.bcx.ins().bnot(val),
 429                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 430                             }
 431                         }
 432                         UnOp::Neg => match layout.ty.sty {
 433                             ty::Int(_) => {
 434                                 let clif_ty = fx.clif_type(layout.ty).unwrap();
 435                                 let zero = fx.bcx.ins().iconst(clif_ty, 0);
 436                                 fx.bcx.ins().isub(zero, val)
 437                             }
 438                             ty::Float(_) => fx.bcx.ins().fneg(val),
 439                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 440                         },
 441                     };
 442                     lval.write_cvalue(fx, CValue::ByVal(res, layout));
 443                 }
 444                 Rvalue::Cast(CastKind::ReifyFnPointer, operand, ty) => {
 445                     let layout = fx.layout_of(ty);
 446                     match fx
 447                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 448                         .sty
 449                     {
 450                         ty::FnDef(def_id, substs) => {
 451                             let func_ref = fx.get_function_ref(
 452                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 453                                     .unwrap(),
 454                             );
 455                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 456                             lval.write_cvalue(fx, CValue::ByVal(func_addr, layout));
 457                         }
 458                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 459                     }
 460                 }
 461                 Rvalue::Cast(CastKind::UnsafeFnPointer, operand, ty) => {
 462                     let operand = trans_operand(fx, operand);
 463                     let layout = fx.layout_of(ty);
 464                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 465                 }
 466                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 467                     let operand = trans_operand(fx, operand);
 468                     let from_ty = operand.layout().ty;
 469                     match (&from_ty.sty, &to_ty.sty) {
 470                         (ty::Ref(..), ty::Ref(..))
 471                         | (ty::Ref(..), ty::RawPtr(..))
 472                         | (ty::RawPtr(..), ty::Ref(..))
 473                         | (ty::RawPtr(..), ty::RawPtr(..))
 474                         | (ty::FnPtr(..), ty::RawPtr(..)) => {
 475                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 476                         }
 477                         (ty::RawPtr(..), ty::Uint(_))
 478                         | (ty::RawPtr(..), ty::Int(_))
 479                         | (ty::FnPtr(..), ty::Uint(_))
 480                             if to_ty.sty == fx.tcx.types.usize.sty
 481                                 || to_ty.sty == fx.tcx.types.isize.sty
 482                                 || fx.clif_type(to_ty).unwrap() == pointer_ty(fx.tcx) =>
 483                         {
 484                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 485                         }
 486                         (ty::Uint(_), ty::RawPtr(..)) if from_ty.sty == fx.tcx.types.usize.sty => {
 487                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 488                         }
 489                         (ty::Int(_), ty::RawPtr(..)) if from_ty.sty == fx.tcx.types.isize.sty => {
 490                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 491                         }
 492                         (ty::Char, ty::Uint(_))
 493                         | (ty::Uint(_), ty::Char)
 494                         | (ty::Uint(_), ty::Int(_))
 495                         | (ty::Uint(_), ty::Uint(_)) => {
 496                             let from = operand.load_scalar(fx);
 497                             let res = crate::common::clif_intcast(
 498                                 fx,
 499                                 from,
 500                                 fx.clif_type(to_ty).unwrap(),
 501                                 false,
 502                             );
 503                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 504                         }
 505                         (ty::Int(_), ty::Int(_)) | (ty::Int(_), ty::Uint(_)) => {
 506                             let from = operand.load_scalar(fx);
 507                             let res = crate::common::clif_intcast(
 508                                 fx,
 509                                 from,
 510                                 fx.clif_type(to_ty).unwrap(),
 511                                 true,
 512                             );
 513                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 514                         }
 515                         (ty::Float(from_flt), ty::Float(to_flt)) => {
 516                             let from = operand.load_scalar(fx);
 517                             let res = match (from_flt, to_flt) {
 518                                 (FloatTy::F32, FloatTy::F64) => {
 519                                     fx.bcx.ins().fpromote(types::F64, from)
 520                                 }
 521                                 (FloatTy::F64, FloatTy::F32) => {
 522                                     fx.bcx.ins().fdemote(types::F32, from)
 523                                 }
 524                                 _ => from,
 525                             };
 526                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 527                         }
 528                         (ty::Float(_), ty::Int(_)) => {
 529                             let from = operand.load_scalar(fx);
 530                             let i_type = fx.clif_type(to_ty).unwrap();
 531                             let res = fx.bcx.ins().fcvt_to_sint_sat(i_type, from);
 532                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 533                         }
 534                         (ty::Float(_), ty::Uint(_)) => {
 535                             let from = operand.load_scalar(fx);
 536                             let i_type = fx.clif_type(to_ty).unwrap();
 537                             let res = fx.bcx.ins().fcvt_to_uint_sat(i_type, from);
 538                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 539                         }
 540                         (ty::Int(_), ty::Float(_)) => {
 541                             let from_ty = fx.clif_type(from_ty).unwrap();
 542                             let from = operand.load_scalar(fx);
 543                             // FIXME missing encoding for fcvt_from_sint.f32.i8
 544                             let from = if from_ty == types::I8 || from_ty == types::I16 {
 545                                 fx.bcx.ins().sextend(types::I32, from)
 546                             } else {
 547                                 from
 548                             };
 549                             let f_type = fx.clif_type(to_ty).unwrap();
 550                             let res = fx.bcx.ins().fcvt_from_sint(f_type, from);
 551                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 552                         }
 553                         (ty::Uint(_), ty::Float(_)) => {
 554                             let from_ty = fx.clif_type(from_ty).unwrap();
 555                             let from = operand.load_scalar(fx);
 556                             // FIXME missing encoding for fcvt_from_uint.f32.i8
 557                             let from = if from_ty == types::I8 || from_ty == types::I16 {
 558                                 fx.bcx.ins().uextend(types::I32, from)
 559                             } else {
 560                                 from
 561                             };
 562                             let f_type = fx.clif_type(to_ty).unwrap();
 563                             let res = fx.bcx.ins().fcvt_from_uint(f_type, from);
 564                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 565                         }
 566                         (ty::Bool, ty::Uint(_)) | (ty::Bool, ty::Int(_)) => {
 567                             let to_ty = fx.clif_type(to_ty).unwrap();
 568                             let from = operand.load_scalar(fx);
 569                             let res = if to_ty != types::I8 {
 570                                 fx.bcx.ins().uextend(to_ty, from)
 571                             } else {
 572                                 from
 573                             };
 574                             lval.write_cvalue(fx, CValue::ByVal(res, dest_layout));
 575                         }
 576                         (ty::Adt(adt_def, _substs), ty::Uint(_))
 577                         | (ty::Adt(adt_def, _substs), ty::Int(_))
 578                             if adt_def.is_enum() =>
 579                         {
 580                             // FIXME avoid forcing to stack
 581                             let place =
 582                                 CPlace::Addr(operand.force_stack(fx), None, operand.layout());
 583                             let discr = trans_get_discriminant(fx, place, fx.layout_of(to_ty));
 584                             lval.write_cvalue(fx, discr);
 585                         }
 586                         _ => unimpl!("rval misc {:?} {:?}", from_ty, to_ty),
 587                     }
 588                 }
 589                 Rvalue::Cast(CastKind::ClosureFnPointer, operand, ty) => {
 590                     unimplemented!("rval closure_fn_ptr {:?} {:?}", operand, ty)
 591                 }
 592                 Rvalue::Cast(CastKind::Unsize, operand, _ty) => {
 593                     let operand = trans_operand(fx, operand);
 594                     operand.unsize_value(fx, lval);
 595                 }
 596                 Rvalue::Discriminant(place) => {
 597                     let place = trans_place(fx, place);
 598                     let discr = trans_get_discriminant(fx, place, dest_layout);
 599                     lval.write_cvalue(fx, discr);
 600                 }
 601                 Rvalue::Repeat(operand, times) => {
 602                     let operand = trans_operand(fx, operand);
 603                     for i in 0..*times {
 604                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 605                         let to = lval.place_index(fx, index);
 606                         to.write_cvalue(fx, operand);
 607                     }
 608                 }
 609                 Rvalue::Len(place) => {
 610                     let place = trans_place(fx, place);
 611                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 612                     let len = codegen_array_len(fx, place);
 613                     lval.write_cvalue(fx, CValue::ByVal(len, usize_layout));
 614                 }
 615                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 616                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 617
 618                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 619                     let layout = fx.layout_of(content_ty);
 620                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 621                     let llalign = fx
 622                         .bcx
 623                         .ins()
 624                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 625                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 626
 627                     // Allocate space:
 628                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 629                         Ok(id) => id,
 630                         Err(s) => {
 631                             fx.tcx
 632                                 .sess
 633                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 634                         }
 635                     };
 636                     let instance = ty::Instance::mono(fx.tcx, def_id);
 637                     let func_ref = fx.get_function_ref(instance);
 638                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 639                     let ptr = fx.bcx.inst_results(call)[0];
 640                     lval.write_cvalue(fx, CValue::ByVal(ptr, box_layout));
 641                 }
 642                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 643                     assert!(lval
 644                         .layout()
 645                         .ty
 646                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 647                     let ty_size = fx.layout_of(ty).size.bytes();
 648                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size as i64);
 649                     lval.write_cvalue(fx, val);
 650                 }
 651                 Rvalue::Aggregate(kind, operands) => match **kind {
 652                     AggregateKind::Array(_ty) => {
 653                         for (i, operand) in operands.into_iter().enumerate() {
 654                             let operand = trans_operand(fx, operand);
 655                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 656                             let to = lval.place_index(fx, index);
 657                             to.write_cvalue(fx, operand);
 658                         }
 659                     }
 660                     _ => unimpl!("shouldn't exist at trans {:?}", rval),
 661                 },
 662             }
 663         }
 664         StatementKind::StorageLive(_)
 665         | StatementKind::StorageDead(_)
 666         | StatementKind::Nop
 667         | StatementKind::FakeRead(..)
 668         | StatementKind::Retag { .. }
 669         | StatementKind::AscribeUserType(..) => {}
 670
 671         StatementKind::InlineAsm { .. } => unimpl!("Inline assembly is not supported"),
 672     }
 673 }
 674
 675 fn codegen_array_len<'a, 'tcx: 'a>(
 676     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 677     place: CPlace<'tcx>,
 678 ) -> Value {
 679     match place.layout().ty.sty {
 680         ty::Array(_elem_ty, len) => {
 681             let len = crate::constant::force_eval_const(fx, len).unwrap_usize(fx.tcx) as i64;
 682             fx.bcx.ins().iconst(fx.pointer_type, len)
 683         }
 684         ty::Slice(_elem_ty) => place
 685             .to_addr_maybe_unsized(fx)
 686             .1
 687             .expect("Length metadata for slice place"),
 688         _ => bug!("Rvalue::Len({:?})", place),
 689     }
 690 }
 691
 692 pub fn trans_get_discriminant<'a, 'tcx: 'a>(
 693     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 694     place: CPlace<'tcx>,
 695     dest_layout: TyLayout<'tcx>,
 696 ) -> CValue<'tcx> {
 697     let layout = place.layout();
 698
 699     if layout.abi == layout::Abi::Uninhabited {
 700         trap_unreachable(&mut fx.bcx);
 701     }
 702     match layout.variants {
 703         layout::Variants::Single { index } => {
 704             let discr_val = layout
 705                 .ty
 706                 .ty_adt_def()
 707                 .map_or(index.as_u32() as u128, |def| {
 708                     def.discriminant_for_variant(fx.tcx, index).val
 709                 });
 710             return CValue::const_val(fx, dest_layout.ty, discr_val as u64 as i64);
 711         }
 712         layout::Variants::Tagged { .. } | layout::Variants::NicheFilling { .. } => {}
 713     }
 714
 715     let discr = place.place_field(fx, mir::Field::new(0)).to_cvalue(fx);
 716     let discr_ty = discr.layout().ty;
 717     let lldiscr = discr.load_scalar(fx);
 718     match layout.variants {
 719         layout::Variants::Single { .. } => bug!(),
 720         layout::Variants::Tagged { ref tag, .. } => {
 721             let signed = match tag.value {
 722                 layout::Int(_, signed) => signed,
 723                 _ => false,
 724             };
 725             let val = clif_intcast(fx, lldiscr, fx.clif_type(dest_layout.ty).unwrap(), signed);
 726             return CValue::ByVal(val, dest_layout);
 727         }
 728         layout::Variants::NicheFilling {
 729             dataful_variant,
 730             ref niche_variants,
 731             niche_start,
 732             ..
 733         } => {
 734             let niche_llty = fx.clif_type(discr_ty).unwrap();
 735             let dest_clif_ty = fx.clif_type(dest_layout.ty).unwrap();
 736             if niche_variants.start() == niche_variants.end() {
 737                 let b = fx
 738                     .bcx
 739                     .ins()
 740                     .icmp_imm(IntCC::Equal, lldiscr, niche_start as u64 as i64);
 741                 let if_true = fx
 742                     .bcx
 743                     .ins()
 744                     .iconst(dest_clif_ty, niche_variants.start().as_u32() as i64);
 745                 let if_false = fx
 746                     .bcx
 747                     .ins()
 748                     .iconst(dest_clif_ty, dataful_variant.as_u32() as i64);
 749                 let val = fx.bcx.ins().select(b, if_true, if_false);
 750                 return CValue::ByVal(val, dest_layout);
 751             } else {
 752                 // Rebase from niche values to discriminant values.
 753                 let delta = niche_start.wrapping_sub(niche_variants.start().as_u32() as u128);
 754                 let delta = fx.bcx.ins().iconst(niche_llty, delta as u64 as i64);
 755                 let lldiscr = fx.bcx.ins().isub(lldiscr, delta);
 756                 let b = fx.bcx.ins().icmp_imm(
 757                     IntCC::UnsignedLessThanOrEqual,
 758                     lldiscr,
 759                     niche_variants.end().as_u32() as i64,
 760                 );
 761                 let if_true =
 762                     clif_intcast(fx, lldiscr, fx.clif_type(dest_layout.ty).unwrap(), false);
 763                 let if_false = fx
 764                     .bcx
 765                     .ins()
 766                     .iconst(dest_clif_ty, dataful_variant.as_u32() as i64);
 767                 let val = fx.bcx.ins().select(b, if_true, if_false);
 768                 return CValue::ByVal(val, dest_layout);
 769             }
 770         }
 771     }
 772 }
 773
 774 macro_rules! binop_match {
 775     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, bug) => {
 776         bug!("binop {} on {} lhs: {:?} rhs: {:?}", stringify!($var), $bug_fmt, $lhs, $rhs)
 777     };
 778     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, icmp($cc:ident)) => {{
 779         assert_eq!($fx.tcx.types.bool, $ret_ty);
 780         let ret_layout = $fx.layout_of($ret_ty);
 781
 782         let b = $fx.bcx.ins().icmp(IntCC::$cc, $lhs, $rhs);
 783         CValue::ByVal($fx.bcx.ins().bint(types::I8, b), ret_layout)
 784     }};
 785     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, fcmp($cc:ident)) => {{
 786         assert_eq!($fx.tcx.types.bool, $ret_ty);
 787         let ret_layout = $fx.layout_of($ret_ty);
 788         let b = $fx.bcx.ins().fcmp(FloatCC::$cc, $lhs, $rhs);
 789         CValue::ByVal($fx.bcx.ins().bint(types::I8, b), ret_layout)
 790     }};
 791     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, custom(|| $body:expr)) => {{
 792         $body
 793     }};
 794     (@single $fx:expr, $bug_fmt:expr, $var:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, $name:ident) => {{
 795         let ret_layout = $fx.layout_of($ret_ty);
 796         CValue::ByVal($fx.bcx.ins().$name($lhs, $rhs), ret_layout)
 797     }};
 798     (
 799         $fx:expr, $bin_op:expr, $signed:expr, $lhs:expr, $rhs:expr, $ret_ty:expr, $bug_fmt:expr;
 800         $(
 801             $var:ident ($sign:pat) $name:tt $( ( $($next:tt)* ) )? ;
 802         )*
 803     ) => {{
 804         let lhs = $lhs.load_scalar($fx);
 805         let rhs = $rhs.load_scalar($fx);
 806         match ($bin_op, $signed) {
 807             $(
 808                 (BinOp::$var, $sign) => binop_match!(@single $fx, $bug_fmt, $var, $signed, lhs, rhs, $ret_ty, $name $( ( $($next)* ) )?),
 809             )*
 810         }
 811     }}
 812 }
 813
 814 fn trans_bool_binop<'a, 'tcx: 'a>(
 815     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 816     bin_op: BinOp,
 817     lhs: CValue<'tcx>,
 818     rhs: CValue<'tcx>,
 819     ty: Ty<'tcx>,
 820 ) -> CValue<'tcx> {
 821     let res = binop_match! {
 822         fx, bin_op, false, lhs, rhs, ty, "bool";
 823         Add (_) bug;
 824         Sub (_) bug;
 825         Mul (_) bug;
 826         Div (_) bug;
 827         Rem (_) bug;
 828         BitXor (_) bxor;
 829         BitAnd (_) band;
 830         BitOr (_) bor;
 831         Shl (_) bug;
 832         Shr (_) bug;
 833
 834         Eq (_) icmp(Equal);
 835         Lt (_) icmp(UnsignedLessThan);
 836         Le (_) icmp(UnsignedLessThanOrEqual);
 837         Ne (_) icmp(NotEqual);
 838         Ge (_) icmp(UnsignedGreaterThanOrEqual);
 839         Gt (_) icmp(UnsignedGreaterThan);
 840
 841         Offset (_) bug;
 842     };
 843
 844     res
 845 }
 846
 847 pub fn trans_int_binop<'a, 'tcx: 'a>(
 848     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 849     bin_op: BinOp,
 850     lhs: CValue<'tcx>,
 851     rhs: CValue<'tcx>,
 852     out_ty: Ty<'tcx>,
 853     signed: bool,
 854 ) -> CValue<'tcx> {
 855     if bin_op != BinOp::Shl && bin_op != BinOp::Shr {
 856         assert_eq!(
 857             lhs.layout().ty,
 858             rhs.layout().ty,
 859             "int binop requires lhs and rhs of same type"
 860         );
 861     }
 862     binop_match! {
 863         fx, bin_op, signed, lhs, rhs, out_ty, "int/uint";
 864         Add (_) iadd;
 865         Sub (_) isub;
 866         Mul (_) imul;
 867         Div (false) udiv;
 868         Div (true) sdiv;
 869         Rem (false) urem;
 870         Rem (true) srem;
 871         BitXor (_) bxor;
 872         BitAnd (_) band;
 873         BitOr (_) bor;
 874         Shl (_) ishl;
 875         Shr (false) ushr;
 876         Shr (true) sshr;
 877
 878         Eq (_) icmp(Equal);
 879         Lt (false) icmp(UnsignedLessThan);
 880         Lt (true) icmp(SignedLessThan);
 881         Le (false) icmp(UnsignedLessThanOrEqual);
 882         Le (true) icmp(SignedLessThanOrEqual);
 883         Ne (_) icmp(NotEqual);
 884         Ge (false) icmp(UnsignedGreaterThanOrEqual);
 885         Ge (true) icmp(SignedGreaterThanOrEqual);
 886         Gt (false) icmp(UnsignedGreaterThan);
 887         Gt (true) icmp(SignedGreaterThan);
 888
 889         Offset (_) bug;
 890     }
 891 }
 892
 893 pub fn trans_checked_int_binop<'a, 'tcx: 'a>(
 894     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 895     bin_op: BinOp,
 896     in_lhs: CValue<'tcx>,
 897     in_rhs: CValue<'tcx>,
 898     out_ty: Ty<'tcx>,
 899     signed: bool,
 900 ) -> CValue<'tcx> {
 901     if bin_op != BinOp::Shl && bin_op != BinOp::Shr {
 902         assert_eq!(
 903             in_lhs.layout().ty,
 904             in_rhs.layout().ty,
 905             "checked int binop requires lhs and rhs of same type"
 906         );
 907     }
 908
 909     let lhs = in_lhs.load_scalar(fx);
 910     let rhs = in_rhs.load_scalar(fx);
 911     let res = match bin_op {
 912         BinOp::Add => fx.bcx.ins().iadd(lhs, rhs),
 913         BinOp::Sub => fx.bcx.ins().isub(lhs, rhs),
 914         BinOp::Mul => fx.bcx.ins().imul(lhs, rhs),
 915         BinOp::Shl => fx.bcx.ins().ishl(lhs, rhs),
 916         BinOp::Shr => {
 917             if !signed {
 918                 fx.bcx.ins().ushr(lhs, rhs)
 919             } else {
 920                 fx.bcx.ins().sshr(lhs, rhs)
 921             }
 922         }
 923         _ => bug!(
 924             "binop {:?} on checked int/uint lhs: {:?} rhs: {:?}",
 925             bin_op,
 926             in_lhs,
 927             in_rhs
 928         ),
 929     };
 930
 931     // TODO: check for overflow
 932     let has_overflow = fx.bcx.ins().iconst(types::I8, 0);
 933
 934     let out_place = CPlace::new_stack_slot(fx, out_ty);
 935     let out_layout = out_place.layout();
 936     out_place.write_cvalue(fx, CValue::ByValPair(res, has_overflow, out_layout));
 937
 938     out_place.to_cvalue(fx)
 939 }
 940
 941 fn trans_float_binop<'a, 'tcx: 'a>(
 942     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 943     bin_op: BinOp,
 944     lhs: CValue<'tcx>,
 945     rhs: CValue<'tcx>,
 946     ty: Ty<'tcx>,
 947 ) -> CValue<'tcx> {
 948     let res = binop_match! {
 949         fx, bin_op, false, lhs, rhs, ty, "float";
 950         Add (_) fadd;
 951         Sub (_) fsub;
 952         Mul (_) fmul;
 953         Div (_) fdiv;
 954         Rem (_) custom(|| {
 955             assert_eq!(lhs.layout().ty, ty);
 956             assert_eq!(rhs.layout().ty, ty);
 957             match ty.sty {
 958                 ty::Float(FloatTy::F32) => fx.easy_call("fmodf", &[lhs, rhs], ty),
 959                 ty::Float(FloatTy::F64) => fx.easy_call("fmod", &[lhs, rhs], ty),
 960                 _ => bug!(),
 961             }
 962         });
 963         BitXor (_) bxor;
 964         BitAnd (_) band;
 965         BitOr (_) bor;
 966         Shl (_) bug;
 967         Shr (_) bug;
 968
 969         Eq (_) fcmp(Equal);
 970         Lt (_) fcmp(LessThan);
 971         Le (_) fcmp(LessThanOrEqual);
 972         Ne (_) fcmp(NotEqual);
 973         Ge (_) fcmp(GreaterThanOrEqual);
 974         Gt (_) fcmp(GreaterThan);
 975
 976         Offset (_) bug;
 977     };
 978
 979     res
 980 }
 981
 982 fn trans_char_binop<'a, 'tcx: 'a>(
 983     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
 984     bin_op: BinOp,
 985     lhs: CValue<'tcx>,
 986     rhs: CValue<'tcx>,
 987     ty: Ty<'tcx>,
 988 ) -> CValue<'tcx> {
 989     let res = binop_match! {
 990         fx, bin_op, false, lhs, rhs, ty, "char";
 991         Add (_) bug;
 992         Sub (_) bug;
 993         Mul (_) bug;
 994         Div (_) bug;
 995         Rem (_) bug;
 996         BitXor (_) bug;
 997         BitAnd (_) bug;
 998         BitOr (_) bug;
 999         Shl (_) bug;
1000         Shr (_) bug;
1001
1002         Eq (_) icmp(Equal);
1003         Lt (_) icmp(UnsignedLessThan);
1004         Le (_) icmp(UnsignedLessThanOrEqual);
1005         Ne (_) icmp(NotEqual);
1006         Ge (_) icmp(UnsignedGreaterThanOrEqual);
1007         Gt (_) icmp(UnsignedGreaterThan);
1008
1009         Offset (_) bug;
1010     };
1011
1012     res
1013 }
1014
1015 fn trans_ptr_binop<'a, 'tcx: 'a>(
1016     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1017     bin_op: BinOp,
1018     lhs: CValue<'tcx>,
1019     rhs: CValue<'tcx>,
1020     ret_ty: Ty<'tcx>,
1021 ) -> CValue<'tcx> {
1022     let not_fat = match lhs.layout().ty.sty {
1023         ty::RawPtr(TypeAndMut { ty, mutbl: _ }) => {
1024             ty.is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all())
1025         }
1026         ty::FnPtr(..) => true,
1027         _ => bug!("trans_ptr_binop on non ptr"),
1028     };
1029     if not_fat {
1030         if let BinOp::Offset = bin_op {
1031             let (base, offset) = (lhs, rhs.load_scalar(fx));
1032             let pointee_ty = base.layout().ty.builtin_deref(true).unwrap().ty;
1033             let pointee_size = fx.layout_of(pointee_ty).size.bytes();
1034             let ptr_diff = fx.bcx.ins().imul_imm(offset, pointee_size as i64);
1035             let base_val = base.load_scalar(fx);
1036             let res = fx.bcx.ins().iadd(base_val, ptr_diff);
1037             return CValue::ByVal(res, base.layout());
1038         }
1039
1040         binop_match! {
1041             fx, bin_op, false, lhs, rhs, ret_ty, "ptr";
1042             Add (_) bug;
1043             Sub (_) bug;
1044             Mul (_) bug;
1045             Div (_) bug;
1046             Rem (_) bug;
1047             BitXor (_) bug;
1048             BitAnd (_) bug;
1049             BitOr (_) bug;
1050             Shl (_) bug;
1051             Shr (_) bug;
1052
1053             Eq (_) icmp(Equal);
1054             Lt (_) icmp(UnsignedLessThan);
1055             Le (_) icmp(UnsignedLessThanOrEqual);
1056             Ne (_) icmp(NotEqual);
1057             Ge (_) icmp(UnsignedGreaterThanOrEqual);
1058             Gt (_) icmp(UnsignedGreaterThan);
1059
1060             Offset (_) bug; // Handled above
1061         }
1062     } else {
1063         let (lhs_ptr, lhs_extra) = lhs.load_value_pair(fx);
1064         let (rhs_ptr, rhs_extra) = rhs.load_value_pair(fx);
1065         let res = match bin_op {
1066             BinOp::Eq => {
1067                 let ptr_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_ptr, rhs_ptr);
1068                 let extra_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_extra, rhs_extra);
1069                 fx.bcx.ins().band(ptr_eq, extra_eq)
1070             }
1071             BinOp::Ne => {
1072                 let ptr_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_ptr, rhs_ptr);
1073                 let extra_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_extra, rhs_extra);
1074                 fx.bcx.ins().bor(ptr_ne, extra_ne)
1075             }
1076             _ => unimplemented!(
1077                 "trans_ptr_binop({:?}, <fat ptr>, <fat ptr>) not implemented",
1078                 bin_op
1079             ),
1080         };
1081
1082         assert_eq!(fx.tcx.types.bool, ret_ty);
1083         let ret_layout = fx.layout_of(ret_ty);
1084         CValue::ByVal(fx.bcx.ins().bint(types::I8, res), ret_layout)
1085     }
1086 }
1087
1088 pub fn trans_place<'a, 'tcx: 'a>(
1089     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1090     place: &Place<'tcx>,
1091 ) -> CPlace<'tcx> {
1092     match place {
1093         Place::Base(base) => match base {
1094             PlaceBase::Local(local) => fx.get_local_place(*local),
1095             PlaceBase::Promoted(promoted) => crate::constant::trans_promoted(fx, promoted.0),
1096             PlaceBase::Static(static_) => crate::constant::codegen_static_ref(fx, static_),
1097         }
1098         Place::Projection(projection) => {
1099             let base = trans_place(fx, &projection.base);
1100             match projection.elem {
1101                 ProjectionElem::Deref => base.place_deref(fx),
1102                 ProjectionElem::Field(field, _ty) => base.place_field(fx, field),
1103                 ProjectionElem::Index(local) => {
1104                     let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
1105                     base.place_index(fx, index)
1106                 }
1107                 ProjectionElem::ConstantIndex {
1108                     offset,
1109                     min_length: _,
1110                     from_end,
1111                 } => {
1112                     let index = if !from_end {
1113                         fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
1114                     } else {
1115                         let len = codegen_array_len(fx, base);
1116                         fx.bcx.ins().iadd_imm(len, -(offset as i64))
1117                     };
1118                     base.place_index(fx, index)
1119                 }
1120                 ProjectionElem::Subslice { from, to } => {
1121                     // These indices are generated by slice patterns.
1122                     // slice[from:-to] in Python terms.
1123
1124                     match base.layout().ty.sty {
1125                         ty::Array(elem_ty, len) => {
1126                             let elem_layout = fx.layout_of(elem_ty);
1127                             let ptr = base.to_addr(fx);
1128                             let len = crate::constant::force_eval_const(fx, len).unwrap_usize(fx.tcx);
1129                             CPlace::Addr(
1130                                 fx.bcx.ins().iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
1131                                 None,
1132                                 fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
1133                             )
1134                         }
1135                         ty::Slice(elem_ty) => {
1136                             let elem_layout = fx.layout_of(elem_ty);
1137                             let (ptr, len) = base.to_addr_maybe_unsized(fx);
1138                             let len = len.unwrap();
1139                             CPlace::Addr(
1140                                 fx.bcx.ins().iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
1141                                 Some(fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64))),
1142                                 base.layout(),
1143                             )
1144                         }
1145                         _ => unreachable!(),
1146                     }
1147                 }
1148                 ProjectionElem::Downcast(_adt_def, variant) => base.downcast_variant(fx, variant),
1149             }
1150         }
1151     }
1152 }
1153
1154 pub fn trans_operand<'a, 'tcx>(
1155     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
1156     operand: &Operand<'tcx>,
1157 ) -> CValue<'tcx> {
1158     match operand {
1159         Operand::Move(place) | Operand::Copy(place) => {
1160             let cplace = trans_place(fx, place);
1161             cplace.to_cvalue(fx)
1162         }
1163         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
1164     }
1165 }