src/base.rs

   1 use rustc::ty::adjustment::PointerCast;
   2
   3 use crate::prelude::*;
   4
   5 pub fn trans_fn<'clif, 'tcx, B: Backend + 'static>(
   6     cx: &mut crate::CodegenCx<'clif, 'tcx, B>,
   7     instance: Instance<'tcx>,
   8     linkage: Linkage,
   9 ) {
  10     let tcx = cx.tcx;
  11
  12     let mir = tcx.instance_mir(instance.def);
  13
  14     // Declare function
  15     let (name, sig) = get_function_name_and_sig(tcx, instance, false);
  16     let func_id = cx.module.declare_function(&name, linkage, &sig).unwrap();
  17     let mut debug_context = cx
  18         .debug_context
  19         .as_mut()
  20         .map(|debug_context| FunctionDebugContext::new(tcx, debug_context, mir, &name, &sig));
  21
  22     // Make FunctionBuilder
  23     let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
  24     let mut func_ctx = FunctionBuilderContext::new();
  25     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  26
  27     // Predefine ebb's
  28     let start_ebb = bcx.create_ebb();
  29     let mut ebb_map: HashMap<BasicBlock, Ebb> = HashMap::new();
  30     for (bb, _bb_data) in mir.basic_blocks().iter_enumerated() {
  31         ebb_map.insert(bb, bcx.create_ebb());
  32     }
  33
  34     // Make FunctionCx
  35     let pointer_type = cx.module.target_config().pointer_type();
  36     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  37
  38     let mut fx = FunctionCx {
  39         tcx,
  40         module: cx.module,
  41         pointer_type,
  42
  43         instance,
  44         mir,
  45
  46         bcx,
  47         ebb_map,
  48         local_map: HashMap::new(),
  49
  50         clif_comments,
  51         constants_cx: &mut cx.constants_cx,
  52         caches: &mut cx.caches,
  53         source_info_set: indexmap::IndexSet::new(),
  54     };
  55
  56     with_unimpl_span(fx.mir.span, || {
  57         crate::abi::codegen_fn_prelude(&mut fx, start_ebb);
  58         codegen_fn_content(&mut fx);
  59     });
  60
  61     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  62     let instance = fx.instance;
  63     let clif_comments = fx.clif_comments;
  64     let source_info_set = fx.source_info_set;
  65
  66     #[cfg(debug_assertions)]
  67     crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &func, &clif_comments, None);
  68
  69     // Verify function
  70     verify_func(tcx, &clif_comments, &func);
  71
  72     // Define function
  73     let context = &mut cx.caches.context;
  74     context.func = func;
  75     cx.module.define_function(func_id, context).unwrap();
  76
  77     let value_ranges = context
  78         .build_value_labels_ranges(cx.module.isa())
  79         .expect("value location ranges");
  80
  81     // Write optimized function to file for debugging
  82     #[cfg(debug_assertions)]
  83     crate::pretty_clif::write_clif_file(
  84         cx.tcx,
  85         "opt",
  86         instance,
  87         &context.func,
  88         &clif_comments,
  89         Some(&value_ranges),
  90     );
  91
  92     // Define debuginfo for function
  93     let isa = cx.module.isa();
  94     debug_context
  95         .as_mut()
  96         .map(|x| x.define(tcx, context, isa, &source_info_set));
  97
  98     // Clear context to make it usable for the next function
  99     context.clear();
 100 }
 101
 102 fn verify_func(tcx: TyCtxt, writer: &crate::pretty_clif::CommentWriter, func: &Function) {
 103     let flags = settings::Flags::new(settings::builder());
 104     match ::cranelift::codegen::verify_function(&func, &flags) {
 105         Ok(_) => {}
 106         Err(err) => {
 107             tcx.sess.err(&format!("{:?}", err));
 108             let pretty_error = ::cranelift::codegen::print_errors::pretty_verifier_error(
 109                 &func,
 110                 None,
 111                 Some(Box::new(writer)),
 112                 err,
 113             );
 114             tcx.sess
 115                 .fatal(&format!("cranelift verify error:\n{}", pretty_error));
 116         }
 117     }
 118 }
 119
 120 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, impl Backend>) {
 121     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 122         if bb_data.is_cleanup {
 123             // Unwinding after panicking is not supported
 124             continue;
 125         }
 126
 127         let ebb = fx.get_ebb(bb);
 128         fx.bcx.switch_to_block(ebb);
 129
 130         fx.bcx.ins().nop();
 131         for stmt in &bb_data.statements {
 132             fx.set_debug_loc(stmt.source_info);
 133             trans_stmt(fx, ebb, stmt);
 134         }
 135
 136         #[cfg(debug_assertions)]
 137         {
 138             let mut terminator_head = "\n".to_string();
 139             bb_data
 140                 .terminator()
 141                 .kind
 142                 .fmt_head(&mut terminator_head)
 143                 .unwrap();
 144             let inst = fx.bcx.func.layout.last_inst(ebb).unwrap();
 145             fx.add_comment(inst, terminator_head);
 146         }
 147
 148         fx.set_debug_loc(bb_data.terminator().source_info);
 149
 150         match &bb_data.terminator().kind {
 151             TerminatorKind::Goto { target } => {
 152                 let ebb = fx.get_ebb(*target);
 153                 fx.bcx.ins().jump(ebb, &[]);
 154             }
 155             TerminatorKind::Return => {
 156                 crate::abi::codegen_return(fx);
 157             }
 158             TerminatorKind::Assert {
 159                 cond,
 160                 expected,
 161                 msg,
 162                 target,
 163                 cleanup: _,
 164             } => {
 165                 let cond = trans_operand(fx, cond).load_scalar(fx);
 166                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 167                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 168                 let target = fx.get_ebb(*target);
 169                 if *expected {
 170                     fx.bcx.ins().brnz(cond, target, &[]);
 171                 } else {
 172                     fx.bcx.ins().brz(cond, target, &[]);
 173                 };
 174                 trap_panic(
 175                     fx,
 176                     format!(
 177                         "[panic] Assert {:?} at {:?} failed.",
 178                         msg,
 179                         bb_data.terminator().source_info.span
 180                     ),
 181                 );
 182             }
 183
 184             TerminatorKind::SwitchInt {
 185                 discr,
 186                 switch_ty: _,
 187                 values,
 188                 targets,
 189             } => {
 190                 let discr = trans_operand(fx, discr).load_scalar(fx);
 191                 let mut switch = ::cranelift::frontend::Switch::new();
 192                 for (i, value) in values.iter().enumerate() {
 193                     let ebb = fx.get_ebb(targets[i]);
 194                     switch.set_entry(*value as u64, ebb);
 195                 }
 196                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 197                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 198             }
 199             TerminatorKind::Call {
 200                 func,
 201                 args,
 202                 destination,
 203                 cleanup: _,
 204                 from_hir_call: _,
 205             } => {
 206                 crate::abi::codegen_terminator_call(fx, func, args, destination);
 207             }
 208             TerminatorKind::Resume | TerminatorKind::Abort => {
 209                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 210             }
 211             TerminatorKind::Unreachable => {
 212                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 213             }
 214             TerminatorKind::Yield { .. }
 215             | TerminatorKind::FalseEdges { .. }
 216             | TerminatorKind::FalseUnwind { .. }
 217             | TerminatorKind::DropAndReplace { .. }
 218             | TerminatorKind::GeneratorDrop => {
 219                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 220             }
 221             TerminatorKind::Drop {
 222                 location,
 223                 target,
 224                 unwind: _,
 225             } => {
 226                 let drop_place = trans_place(fx, location);
 227                 crate::abi::codegen_drop(fx, drop_place);
 228
 229                 let target_ebb = fx.get_ebb(*target);
 230                 fx.bcx.ins().jump(target_ebb, &[]);
 231             }
 232         };
 233     }
 234
 235     fx.bcx.seal_all_blocks();
 236     fx.bcx.finalize();
 237 }
 238
 239 fn trans_stmt<'tcx>(
 240     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 241     cur_ebb: Ebb,
 242     stmt: &Statement<'tcx>,
 243 ) {
 244     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 245
 246     fx.set_debug_loc(stmt.source_info);
 247
 248     #[cfg(debug_assertions)]
 249     match &stmt.kind {
 250         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 251         _ => {
 252             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 253             fx.add_comment(inst, format!("{:?}", stmt));
 254         }
 255     }
 256
 257     match &stmt.kind {
 258         StatementKind::SetDiscriminant {
 259             place,
 260             variant_index,
 261         } => {
 262             let place = trans_place(fx, place);
 263             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 264         }
 265         StatementKind::Assign(to_place, rval) => {
 266             let lval = trans_place(fx, to_place);
 267             let dest_layout = lval.layout();
 268             match &**rval {
 269                 Rvalue::Use(operand) => {
 270                     let val = trans_operand(fx, operand);
 271                     lval.write_cvalue(fx, val);
 272                 }
 273                 Rvalue::Ref(_, _, place) => {
 274                     let place = trans_place(fx, place);
 275                     place.write_place_ref(fx, lval);
 276                 }
 277                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 278                     let lhs = trans_operand(fx, lhs);
 279                     let rhs = trans_operand(fx, rhs);
 280
 281                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 282                     lval.write_cvalue(fx, res);
 283                 }
 284                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 285                     let lhs = trans_operand(fx, lhs);
 286                     let rhs = trans_operand(fx, rhs);
 287
 288                     let res = if !fx.tcx.sess.overflow_checks() {
 289                         let val =
 290                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 291                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 292                         CValue::by_val_pair(val, is_overflow, lval.layout())
 293                     } else {
 294                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 295                     };
 296
 297                     lval.write_cvalue(fx, res);
 298                 }
 299                 Rvalue::UnaryOp(un_op, operand) => {
 300                     let operand = trans_operand(fx, operand);
 301                     let layout = operand.layout();
 302                     let val = operand.load_scalar(fx);
 303                     let res = match un_op {
 304                         UnOp::Not => {
 305                             match layout.ty.sty {
 306                                 ty::Bool => {
 307                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 308                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 309                                     fx.bcx.ins().bint(types::I8, res)
 310                                 }
 311                                 ty::Uint(_) | ty::Int(_) => fx.bcx.ins().bnot(val),
 312                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 313                             }
 314                         }
 315                         UnOp::Neg => match layout.ty.sty {
 316                             ty::Int(_) => {
 317                                 let clif_ty = fx.clif_type(layout.ty).unwrap();
 318                                 if clif_ty == types::I128 {
 319                                     // FIXME implement it
 320                                     crate::trap::trap_unreachable_ret_value(
 321                                         fx,
 322                                         layout,
 323                                         "i128 neg is not yet supported",
 324                                     )
 325                                     .load_scalar(fx)
 326                                 } else {
 327                                     let zero = fx.bcx.ins().iconst(clif_ty, 0);
 328                                     fx.bcx.ins().isub(zero, val)
 329                                 }
 330                             }
 331                             ty::Float(_) => fx.bcx.ins().fneg(val),
 332                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 333                         },
 334                     };
 335                     lval.write_cvalue(fx, CValue::by_val(res, layout));
 336                 }
 337                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 338                     let layout = fx.layout_of(ty);
 339                     match fx
 340                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 341                         .sty
 342                     {
 343                         ty::FnDef(def_id, substs) => {
 344                             let func_ref = fx.get_function_ref(
 345                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 346                                     .unwrap(),
 347                             );
 348                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 349                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 350                         }
 351                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 352                     }
 353                 }
 354                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 355                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty) => {
 356                     let operand = trans_operand(fx, operand);
 357                     let layout = fx.layout_of(ty);
 358                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 359                 }
 360                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 361                     let operand = trans_operand(fx, operand);
 362                     let from_ty = operand.layout().ty;
 363
 364                     fn is_fat_ptr<'tcx>(
 365                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 366                         ty: Ty<'tcx>,
 367                     ) -> bool {
 368                         ty.builtin_deref(true)
 369                             .map(
 370                                 |ty::TypeAndMut {
 371                                      ty: pointee_ty,
 372                                      mutbl: _,
 373                                  }| {
 374                                     fx.layout_of(pointee_ty).is_unsized()
 375                                 },
 376                             )
 377                             .unwrap_or(false)
 378                     }
 379
 380                     if is_fat_ptr(fx, from_ty) {
 381                         if is_fat_ptr(fx, to_ty) {
 382                             // fat-ptr -> fat-ptr
 383                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 384                         } else {
 385                             // fat-ptr -> thin-ptr
 386                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 387                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 388                         }
 389                     } else if let ty::Adt(adt_def, _substs) = from_ty.sty {
 390                         // enum -> discriminant value
 391                         assert!(adt_def.is_enum());
 392                         match to_ty.sty {
 393                             ty::Uint(_) | ty::Int(_) => {}
 394                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 395                         }
 396
 397                         let discr = crate::discriminant::codegen_get_discriminant(
 398                             fx,
 399                             operand,
 400                             fx.layout_of(to_ty),
 401                         );
 402                         lval.write_cvalue(fx, discr);
 403                     } else {
 404                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 405                         let from = operand.load_scalar(fx);
 406
 407                         let res = clif_int_or_float_cast(
 408                             fx,
 409                             from,
 410                             type_sign(from_ty),
 411                             to_clif_ty,
 412                             type_sign(to_ty),
 413                         );
 414                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 415                     }
 416                 }
 417                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
 418                     let operand = trans_operand(fx, operand);
 419                     match operand.layout().ty.sty {
 420                         ty::Closure(def_id, substs) => {
 421                             let instance = Instance::resolve_closure(
 422                                 fx.tcx,
 423                                 def_id,
 424                                 substs,
 425                                 ty::ClosureKind::FnOnce,
 426                             );
 427                             let func_ref = fx.get_function_ref(instance);
 428                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 429                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 430                         }
 431                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 432                     }
 433                 }
 434                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
 435                     let operand = trans_operand(fx, operand);
 436                     operand.unsize_value(fx, lval);
 437                 }
 438                 Rvalue::Discriminant(place) => {
 439                     let place = trans_place(fx, place);
 440                     let value = place.to_cvalue(fx);
 441                     let discr =
 442                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 443                     lval.write_cvalue(fx, discr);
 444                 }
 445                 Rvalue::Repeat(operand, times) => {
 446                     let operand = trans_operand(fx, operand);
 447                     for i in 0..*times {
 448                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 449                         let to = lval.place_index(fx, index);
 450                         to.write_cvalue(fx, operand);
 451                     }
 452                 }
 453                 Rvalue::Len(place) => {
 454                     let place = trans_place(fx, place);
 455                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 456                     let len = codegen_array_len(fx, place);
 457                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 458                 }
 459                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 460                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 461
 462                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 463                     let layout = fx.layout_of(content_ty);
 464                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 465                     let llalign = fx
 466                         .bcx
 467                         .ins()
 468                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 469                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 470
 471                     // Allocate space:
 472                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 473                         Ok(id) => id,
 474                         Err(s) => {
 475                             fx.tcx
 476                                 .sess
 477                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 478                         }
 479                     };
 480                     let instance = ty::Instance::mono(fx.tcx, def_id);
 481                     let func_ref = fx.get_function_ref(instance);
 482                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 483                     let ptr = fx.bcx.inst_results(call)[0];
 484                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 485                 }
 486                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 487                     assert!(lval
 488                         .layout()
 489                         .ty
 490                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 491                     let ty_size = fx.layout_of(ty).size.bytes();
 492                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size.into());
 493                     lval.write_cvalue(fx, val);
 494                 }
 495                 Rvalue::Aggregate(kind, operands) => match **kind {
 496                     AggregateKind::Array(_ty) => {
 497                         for (i, operand) in operands.into_iter().enumerate() {
 498                             let operand = trans_operand(fx, operand);
 499                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 500                             let to = lval.place_index(fx, index);
 501                             to.write_cvalue(fx, operand);
 502                         }
 503                     }
 504                     _ => unimpl!("shouldn't exist at trans {:?}", rval),
 505                 },
 506             }
 507         }
 508         StatementKind::StorageLive(_)
 509         | StatementKind::StorageDead(_)
 510         | StatementKind::Nop
 511         | StatementKind::FakeRead(..)
 512         | StatementKind::Retag { .. }
 513         | StatementKind::AscribeUserType(..) => {}
 514
 515         StatementKind::InlineAsm(asm) => {
 516             use syntax::ast::Name;
 517             let InlineAsm {
 518                 asm,
 519                 outputs: _,
 520                 inputs: _,
 521             } = &**asm;
 522             let rustc::hir::InlineAsm {
 523                 asm: asm_code, // Name
 524                 outputs,       // Vec<Name>
 525                 inputs,        // Vec<Name>
 526                 clobbers,      // Vec<Name>
 527                 volatile,      // bool
 528                 alignstack,    // bool
 529                 dialect: _,    // syntax::ast::AsmDialect
 530                 asm_str_style: _,
 531             } = asm;
 532             match &*asm_code.as_str() {
 533                 "cpuid" | "cpuid\n" => {
 534                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 535
 536                     assert_eq!(outputs.len(), 4);
 537                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 538                         .iter()
 539                         .enumerate()
 540                     {
 541                         assert_eq!(&outputs[i].constraint.as_str(), c);
 542                         assert!(!outputs[i].is_rw);
 543                         assert!(!outputs[i].is_indirect);
 544                     }
 545
 546                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 547
 548                     assert!(!volatile);
 549                     assert!(!alignstack);
 550
 551                     crate::trap::trap_unimplemented(
 552                         fx,
 553                         "__cpuid_count arch intrinsic is not supported",
 554                     );
 555                 }
 556                 "xgetbv" => {
 557                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 558
 559                     assert_eq!(outputs.len(), 2);
 560                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 561                         assert_eq!(&outputs[i].constraint.as_str(), c);
 562                         assert!(!outputs[i].is_rw);
 563                         assert!(!outputs[i].is_indirect);
 564                     }
 565
 566                     assert_eq!(clobbers, &[]);
 567
 568                     assert!(!volatile);
 569                     assert!(!alignstack);
 570
 571                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 572                 }
 573                 _ if fx.tcx.symbol_name(fx.instance).as_str() == "__rust_probestack" => {
 574                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 575                 }
 576                 _ => unimpl!("Inline assembly is not supported"),
 577             }
 578         }
 579     }
 580 }
 581
 582 fn codegen_array_len<'tcx>(
 583     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 584     place: CPlace<'tcx>,
 585 ) -> Value {
 586     match place.layout().ty.sty {
 587         ty::Array(_elem_ty, len) => {
 588             let len = crate::constant::force_eval_const(fx, len)
 589                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 590             fx.bcx.ins().iconst(fx.pointer_type, len)
 591         }
 592         ty::Slice(_elem_ty) => place
 593             .to_addr_maybe_unsized(fx)
 594             .1
 595             .expect("Length metadata for slice place"),
 596         _ => bug!("Rvalue::Len({:?})", place),
 597     }
 598 }
 599
 600 pub fn trans_place<'tcx>(
 601     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 602     place: &Place<'tcx>,
 603 ) -> CPlace<'tcx> {
 604     let base = match &place.base {
 605         PlaceBase::Local(local) => fx.get_local_place(*local),
 606         PlaceBase::Static(static_) => match static_.kind {
 607             StaticKind::Static => {
 608                 crate::constant::codegen_static_ref(fx, static_.def_id, static_.ty)
 609             }
 610             StaticKind::Promoted(promoted, substs) => {
 611                 let instance = Instance::new(static_.def_id, fx.monomorphize(&substs));
 612                 crate::constant::trans_promoted(fx, instance, promoted, static_.ty)
 613             }
 614         },
 615     };
 616
 617     trans_place_projection(fx, base, &place.projection)
 618 }
 619
 620 pub fn trans_place_projection<'tcx>(
 621     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 622     base: CPlace<'tcx>,
 623     projection: &Option<Box<Projection<'tcx>>>,
 624 ) -> CPlace<'tcx> {
 625     let projection = if let Some(projection) = projection {
 626         projection
 627     } else {
 628         return base;
 629     };
 630
 631     let base = trans_place_projection(fx, base, &projection.base);
 632
 633     match projection.elem {
 634         ProjectionElem::Deref => base.place_deref(fx),
 635         ProjectionElem::Field(field, _ty) => base.place_field(fx, field),
 636         ProjectionElem::Index(local) => {
 637             let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 638             base.place_index(fx, index)
 639         }
 640         ProjectionElem::ConstantIndex {
 641             offset,
 642             min_length: _,
 643             from_end,
 644         } => {
 645             let index = if !from_end {
 646                 fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 647             } else {
 648                 let len = codegen_array_len(fx, base);
 649                 fx.bcx.ins().iadd_imm(len, -(offset as i64))
 650             };
 651             base.place_index(fx, index)
 652         }
 653         ProjectionElem::Subslice { from, to } => {
 654             // These indices are generated by slice patterns.
 655             // slice[from:-to] in Python terms.
 656
 657             match base.layout().ty.sty {
 658                 ty::Array(elem_ty, len) => {
 659                     let elem_layout = fx.layout_of(elem_ty);
 660                     let ptr = base.to_addr(fx);
 661                     let len = crate::constant::force_eval_const(fx, len)
 662                         .eval_usize(fx.tcx, ParamEnv::reveal_all());
 663                     CPlace::for_addr(
 664                         fx.bcx
 665                             .ins()
 666                             .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 667                         fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
 668                     )
 669                 }
 670                 ty::Slice(elem_ty) => {
 671                     let elem_layout = fx.layout_of(elem_ty);
 672                     let (ptr, len) = base.to_addr_maybe_unsized(fx);
 673                     let len = len.unwrap();
 674                     CPlace::for_addr_with_extra(
 675                         fx.bcx
 676                             .ins()
 677                             .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 678                         fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 679                         base.layout(),
 680                     )
 681                 }
 682                 _ => unreachable!(),
 683             }
 684         }
 685         ProjectionElem::Downcast(_adt_def, variant) => base.downcast_variant(fx, variant),
 686     }
 687 }
 688
 689 pub fn trans_operand<'tcx>(
 690     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 691     operand: &Operand<'tcx>,
 692 ) -> CValue<'tcx> {
 693     match operand {
 694         Operand::Move(place) | Operand::Copy(place) => {
 695             let cplace = trans_place(fx, place);
 696             cplace.to_cvalue(fx)
 697         }
 698         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 699     }
 700 }