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                 if !fx.tcx.sess.overflow_checks() {
 166                     if let mir::interpret::PanicInfo::OverflowNeg = *msg {
 167                         let target = fx.get_ebb(*target);
 168                         fx.bcx.ins().jump(target, &[]);
 169                         continue;
 170                     }
 171                 }
 172                 let cond = trans_operand(fx, cond).load_scalar(fx);
 173                 // TODO HACK brz/brnz for i8/i16 is not yet implemented
 174                 let cond = fx.bcx.ins().uextend(types::I32, cond);
 175                 let target = fx.get_ebb(*target);
 176                 if *expected {
 177                     fx.bcx.ins().brnz(cond, target, &[]);
 178                 } else {
 179                     fx.bcx.ins().brz(cond, target, &[]);
 180                 };
 181                 trap_panic(
 182                     fx,
 183                     format!(
 184                         "[panic] Assert {:?} at {:?} failed.",
 185                         msg,
 186                         bb_data.terminator().source_info.span
 187                     ),
 188                 );
 189             }
 190
 191             TerminatorKind::SwitchInt {
 192                 discr,
 193                 switch_ty: _,
 194                 values,
 195                 targets,
 196             } => {
 197                 let discr = trans_operand(fx, discr).load_scalar(fx);
 198                 let mut switch = ::cranelift::frontend::Switch::new();
 199                 for (i, value) in values.iter().enumerate() {
 200                     let ebb = fx.get_ebb(targets[i]);
 201                     switch.set_entry(*value as u64, ebb);
 202                 }
 203                 let otherwise_ebb = fx.get_ebb(targets[targets.len() - 1]);
 204                 switch.emit(&mut fx.bcx, discr, otherwise_ebb);
 205             }
 206             TerminatorKind::Call {
 207                 func,
 208                 args,
 209                 destination,
 210                 cleanup: _,
 211                 from_hir_call: _,
 212             } => {
 213                 crate::abi::codegen_terminator_call(fx, func, args, destination);
 214             }
 215             TerminatorKind::Resume | TerminatorKind::Abort => {
 216                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 217             }
 218             TerminatorKind::Unreachable => {
 219                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 220             }
 221             TerminatorKind::Yield { .. }
 222             | TerminatorKind::FalseEdges { .. }
 223             | TerminatorKind::FalseUnwind { .. }
 224             | TerminatorKind::DropAndReplace { .. }
 225             | TerminatorKind::GeneratorDrop => {
 226                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
 227             }
 228             TerminatorKind::Drop {
 229                 location,
 230                 target,
 231                 unwind: _,
 232             } => {
 233                 let drop_place = trans_place(fx, location);
 234                 crate::abi::codegen_drop(fx, drop_place);
 235
 236                 let target_ebb = fx.get_ebb(*target);
 237                 fx.bcx.ins().jump(target_ebb, &[]);
 238             }
 239         };
 240     }
 241
 242     fx.bcx.seal_all_blocks();
 243     fx.bcx.finalize();
 244 }
 245
 246 fn trans_stmt<'tcx>(
 247     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 248     cur_ebb: Ebb,
 249     stmt: &Statement<'tcx>,
 250 ) {
 251     let _print_guard = PrintOnPanic(|| format!("stmt {:?}", stmt));
 252
 253     fx.set_debug_loc(stmt.source_info);
 254
 255     #[cfg(debug_assertions)]
 256     match &stmt.kind {
 257         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 258         _ => {
 259             let inst = fx.bcx.func.layout.last_inst(cur_ebb).unwrap();
 260             fx.add_comment(inst, format!("{:?}", stmt));
 261         }
 262     }
 263
 264     match &stmt.kind {
 265         StatementKind::SetDiscriminant {
 266             place,
 267             variant_index,
 268         } => {
 269             let place = trans_place(fx, place);
 270             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 271         }
 272         StatementKind::Assign(to_place, rval) => {
 273             let lval = trans_place(fx, to_place);
 274             let dest_layout = lval.layout();
 275             match &**rval {
 276                 Rvalue::Use(operand) => {
 277                     let val = trans_operand(fx, operand);
 278                     lval.write_cvalue(fx, val);
 279                 }
 280                 Rvalue::Ref(_, _, place) => {
 281                     let place = trans_place(fx, place);
 282                     place.write_place_ref(fx, lval);
 283                 }
 284                 Rvalue::BinaryOp(bin_op, lhs, rhs) => {
 285                     let lhs = trans_operand(fx, lhs);
 286                     let rhs = trans_operand(fx, rhs);
 287
 288                     let res = crate::num::codegen_binop(fx, *bin_op, lhs, rhs);
 289                     lval.write_cvalue(fx, res);
 290                 }
 291                 Rvalue::CheckedBinaryOp(bin_op, lhs, rhs) => {
 292                     let lhs = trans_operand(fx, lhs);
 293                     let rhs = trans_operand(fx, rhs);
 294
 295                     let res = if !fx.tcx.sess.overflow_checks() {
 296                         let val =
 297                             crate::num::trans_int_binop(fx, *bin_op, lhs, rhs).load_scalar(fx);
 298                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 299                         CValue::by_val_pair(val, is_overflow, lval.layout())
 300                     } else {
 301                         crate::num::trans_checked_int_binop(fx, *bin_op, lhs, rhs)
 302                     };
 303
 304                     lval.write_cvalue(fx, res);
 305                 }
 306                 Rvalue::UnaryOp(un_op, operand) => {
 307                     let operand = trans_operand(fx, operand);
 308                     let layout = operand.layout();
 309                     let val = operand.load_scalar(fx);
 310                     let res = match un_op {
 311                         UnOp::Not => {
 312                             match layout.ty.sty {
 313                                 ty::Bool => {
 314                                     let val = fx.bcx.ins().uextend(types::I32, val); // WORKAROUND for CraneStation/cranelift#466
 315                                     let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 316                                     fx.bcx.ins().bint(types::I8, res)
 317                                 }
 318                                 ty::Uint(_) | ty::Int(_) => fx.bcx.ins().bnot(val),
 319                                 _ => unimplemented!("un op Not for {:?}", layout.ty),
 320                             }
 321                         }
 322                         UnOp::Neg => match layout.ty.sty {
 323                             ty::Int(_) => {
 324                                 let clif_ty = fx.clif_type(layout.ty).unwrap();
 325                                 if clif_ty == types::I128 {
 326                                     // FIXME implement it
 327                                     crate::trap::trap_unreachable_ret_value(
 328                                         fx,
 329                                         layout,
 330                                         "i128 neg is not yet supported",
 331                                     )
 332                                     .load_scalar(fx)
 333                                 } else {
 334                                     let zero = fx.bcx.ins().iconst(clif_ty, 0);
 335                                     fx.bcx.ins().isub(zero, val)
 336                                 }
 337                             }
 338                             ty::Float(_) => fx.bcx.ins().fneg(val),
 339                             _ => unimplemented!("un op Neg for {:?}", layout.ty),
 340                         },
 341                     };
 342                     lval.write_cvalue(fx, CValue::by_val(res, layout));
 343                 }
 344                 Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
 345                     let layout = fx.layout_of(ty);
 346                     match fx
 347                         .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
 348                         .sty
 349                     {
 350                         ty::FnDef(def_id, substs) => {
 351                             let func_ref = fx.get_function_ref(
 352                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
 353                                     .unwrap(),
 354                             );
 355                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 356                             lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
 357                         }
 358                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
 359                     }
 360                 }
 361                 Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
 362                 | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty) => {
 363                     let operand = trans_operand(fx, operand);
 364                     let layout = fx.layout_of(ty);
 365                     lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
 366                 }
 367                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
 368                     let operand = trans_operand(fx, operand);
 369                     let from_ty = operand.layout().ty;
 370
 371                     fn is_fat_ptr<'tcx>(
 372                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
 373                         ty: Ty<'tcx>,
 374                     ) -> bool {
 375                         ty.builtin_deref(true)
 376                             .map(
 377                                 |ty::TypeAndMut {
 378                                      ty: pointee_ty,
 379                                      mutbl: _,
 380                                  }| {
 381                                     fx.layout_of(pointee_ty).is_unsized()
 382                                 },
 383                             )
 384                             .unwrap_or(false)
 385                     }
 386
 387                     if is_fat_ptr(fx, from_ty) {
 388                         if is_fat_ptr(fx, to_ty) {
 389                             // fat-ptr -> fat-ptr
 390                             lval.write_cvalue(fx, operand.unchecked_cast_to(dest_layout));
 391                         } else {
 392                             // fat-ptr -> thin-ptr
 393                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 394                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 395                         }
 396                     } else if let ty::Adt(adt_def, _substs) = from_ty.sty {
 397                         // enum -> discriminant value
 398                         assert!(adt_def.is_enum());
 399                         match to_ty.sty {
 400                             ty::Uint(_) | ty::Int(_) => {}
 401                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 402                         }
 403
 404                         let discr = crate::discriminant::codegen_get_discriminant(
 405                             fx,
 406                             operand,
 407                             fx.layout_of(to_ty),
 408                         );
 409                         lval.write_cvalue(fx, discr);
 410                     } else {
 411                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 412                         let from = operand.load_scalar(fx);
 413
 414                         let res = clif_int_or_float_cast(
 415                             fx,
 416                             from,
 417                             type_sign(from_ty),
 418                             to_clif_ty,
 419                             type_sign(to_ty),
 420                         );
 421                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 422                     }
 423                 }
 424                 Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
 425                     let operand = trans_operand(fx, operand);
 426                     match operand.layout().ty.sty {
 427                         ty::Closure(def_id, substs) => {
 428                             let instance = Instance::resolve_closure(
 429                                 fx.tcx,
 430                                 def_id,
 431                                 substs,
 432                                 ty::ClosureKind::FnOnce,
 433                             );
 434                             let func_ref = fx.get_function_ref(instance);
 435                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 436                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 437                         }
 438                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 439                     }
 440                 }
 441                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
 442                     let operand = trans_operand(fx, operand);
 443                     operand.unsize_value(fx, lval);
 444                 }
 445                 Rvalue::Discriminant(place) => {
 446                     let place = trans_place(fx, place);
 447                     let value = place.to_cvalue(fx);
 448                     let discr =
 449                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 450                     lval.write_cvalue(fx, discr);
 451                 }
 452                 Rvalue::Repeat(operand, times) => {
 453                     let operand = trans_operand(fx, operand);
 454                     for i in 0..*times {
 455                         let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 456                         let to = lval.place_index(fx, index);
 457                         to.write_cvalue(fx, operand);
 458                     }
 459                 }
 460                 Rvalue::Len(place) => {
 461                     let place = trans_place(fx, place);
 462                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 463                     let len = codegen_array_len(fx, place);
 464                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 465                 }
 466                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 467                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 468
 469                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 470                     let layout = fx.layout_of(content_ty);
 471                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 472                     let llalign = fx
 473                         .bcx
 474                         .ins()
 475                         .iconst(usize_type, layout.align.abi.bytes() as i64);
 476                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 477
 478                     // Allocate space:
 479                     let def_id = match fx.tcx.lang_items().require(ExchangeMallocFnLangItem) {
 480                         Ok(id) => id,
 481                         Err(s) => {
 482                             fx.tcx
 483                                 .sess
 484                                 .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 485                         }
 486                     };
 487                     let instance = ty::Instance::mono(fx.tcx, def_id);
 488                     let func_ref = fx.get_function_ref(instance);
 489                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 490                     let ptr = fx.bcx.inst_results(call)[0];
 491                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 492                 }
 493                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 494                     assert!(lval
 495                         .layout()
 496                         .ty
 497                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
 498                     let ty_size = fx.layout_of(ty).size.bytes();
 499                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size.into());
 500                     lval.write_cvalue(fx, val);
 501                 }
 502                 Rvalue::Aggregate(kind, operands) => match **kind {
 503                     AggregateKind::Array(_ty) => {
 504                         for (i, operand) in operands.into_iter().enumerate() {
 505                             let operand = trans_operand(fx, operand);
 506                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 507                             let to = lval.place_index(fx, index);
 508                             to.write_cvalue(fx, operand);
 509                         }
 510                     }
 511                     _ => unimpl!("shouldn't exist at trans {:?}", rval),
 512                 },
 513             }
 514         }
 515         StatementKind::StorageLive(_)
 516         | StatementKind::StorageDead(_)
 517         | StatementKind::Nop
 518         | StatementKind::FakeRead(..)
 519         | StatementKind::Retag { .. }
 520         | StatementKind::AscribeUserType(..) => {}
 521
 522         StatementKind::InlineAsm(asm) => {
 523             use syntax::ast::Name;
 524             let InlineAsm {
 525                 asm,
 526                 outputs: _,
 527                 inputs: _,
 528             } = &**asm;
 529             let rustc::hir::InlineAsm {
 530                 asm: asm_code, // Name
 531                 outputs,       // Vec<Name>
 532                 inputs,        // Vec<Name>
 533                 clobbers,      // Vec<Name>
 534                 volatile,      // bool
 535                 alignstack,    // bool
 536                 dialect: _,    // syntax::ast::AsmDialect
 537                 asm_str_style: _,
 538             } = asm;
 539             match &*asm_code.as_str() {
 540                 "cpuid" | "cpuid\n" => {
 541                     assert_eq!(inputs, &[Name::intern("{eax}"), Name::intern("{ecx}")]);
 542
 543                     assert_eq!(outputs.len(), 4);
 544                     for (i, c) in (&["={eax}", "={ebx}", "={ecx}", "={edx}"])
 545                         .iter()
 546                         .enumerate()
 547                     {
 548                         assert_eq!(&outputs[i].constraint.as_str(), c);
 549                         assert!(!outputs[i].is_rw);
 550                         assert!(!outputs[i].is_indirect);
 551                     }
 552
 553                     assert_eq!(clobbers, &[Name::intern("rbx")]);
 554
 555                     assert!(!volatile);
 556                     assert!(!alignstack);
 557
 558                     crate::trap::trap_unimplemented(
 559                         fx,
 560                         "__cpuid_count arch intrinsic is not supported",
 561                     );
 562                 }
 563                 "xgetbv" => {
 564                     assert_eq!(inputs, &[Name::intern("{ecx}")]);
 565
 566                     assert_eq!(outputs.len(), 2);
 567                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 568                         assert_eq!(&outputs[i].constraint.as_str(), c);
 569                         assert!(!outputs[i].is_rw);
 570                         assert!(!outputs[i].is_indirect);
 571                     }
 572
 573                     assert_eq!(clobbers, &[]);
 574
 575                     assert!(!volatile);
 576                     assert!(!alignstack);
 577
 578                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 579                 }
 580                 _ if fx.tcx.symbol_name(fx.instance).name.as_str() == "__rust_probestack" => {
 581                     crate::trap::trap_unimplemented(fx, "__rust_probestack is not supported");
 582                 }
 583                 _ => unimpl!("Inline assembly is not supported"),
 584             }
 585         }
 586     }
 587 }
 588
 589 fn codegen_array_len<'tcx>(
 590     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 591     place: CPlace<'tcx>,
 592 ) -> Value {
 593     match place.layout().ty.sty {
 594         ty::Array(_elem_ty, len) => {
 595             let len = crate::constant::force_eval_const(fx, len)
 596                 .eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 597             fx.bcx.ins().iconst(fx.pointer_type, len)
 598         }
 599         ty::Slice(_elem_ty) => place
 600             .to_addr_maybe_unsized(fx)
 601             .1
 602             .expect("Length metadata for slice place"),
 603         _ => bug!("Rvalue::Len({:?})", place),
 604     }
 605 }
 606
 607 pub fn trans_place<'tcx>(
 608     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 609     place: &Place<'tcx>,
 610 ) -> CPlace<'tcx> {
 611     let base = match &place.base {
 612         PlaceBase::Local(local) => fx.get_local_place(*local),
 613         PlaceBase::Static(static_) => match static_.kind {
 614             StaticKind::Static => {
 615                 crate::constant::codegen_static_ref(fx, static_.def_id, static_.ty)
 616             }
 617             StaticKind::Promoted(promoted, substs) => {
 618                 let instance = Instance::new(static_.def_id, fx.monomorphize(&substs));
 619                 crate::constant::trans_promoted(fx, instance, promoted, static_.ty)
 620             }
 621         },
 622     };
 623
 624     trans_place_projection(fx, base, &place.projection)
 625 }
 626
 627 pub fn trans_place_projection<'tcx>(
 628     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 629     base: CPlace<'tcx>,
 630     projection: &Option<Box<Projection<'tcx>>>,
 631 ) -> CPlace<'tcx> {
 632     let projection = if let Some(projection) = projection {
 633         projection
 634     } else {
 635         return base;
 636     };
 637
 638     let base = trans_place_projection(fx, base, &projection.base);
 639
 640     match projection.elem {
 641         ProjectionElem::Deref => base.place_deref(fx),
 642         ProjectionElem::Field(field, _ty) => base.place_field(fx, field),
 643         ProjectionElem::Index(local) => {
 644             let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 645             base.place_index(fx, index)
 646         }
 647         ProjectionElem::ConstantIndex {
 648             offset,
 649             min_length: _,
 650             from_end,
 651         } => {
 652             let index = if !from_end {
 653                 fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 654             } else {
 655                 let len = codegen_array_len(fx, base);
 656                 fx.bcx.ins().iadd_imm(len, -(offset as i64))
 657             };
 658             base.place_index(fx, index)
 659         }
 660         ProjectionElem::Subslice { from, to } => {
 661             // These indices are generated by slice patterns.
 662             // slice[from:-to] in Python terms.
 663
 664             match base.layout().ty.sty {
 665                 ty::Array(elem_ty, len) => {
 666                     let elem_layout = fx.layout_of(elem_ty);
 667                     let ptr = base.to_addr(fx);
 668                     let len = crate::constant::force_eval_const(fx, len)
 669                         .eval_usize(fx.tcx, ParamEnv::reveal_all());
 670                     CPlace::for_addr(
 671                         fx.bcx
 672                             .ins()
 673                             .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 674                         fx.layout_of(fx.tcx.mk_array(elem_ty, len - from as u64 - to as u64)),
 675                     )
 676                 }
 677                 ty::Slice(elem_ty) => {
 678                     let elem_layout = fx.layout_of(elem_ty);
 679                     let (ptr, len) = base.to_addr_maybe_unsized(fx);
 680                     let len = len.unwrap();
 681                     CPlace::for_addr_with_extra(
 682                         fx.bcx
 683                             .ins()
 684                             .iadd_imm(ptr, elem_layout.size.bytes() as i64 * from as i64),
 685                         fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 686                         base.layout(),
 687                     )
 688                 }
 689                 _ => unreachable!(),
 690             }
 691         }
 692         ProjectionElem::Downcast(_adt_def, variant) => base.downcast_variant(fx, variant),
 693     }
 694 }
 695
 696 pub fn trans_operand<'tcx>(
 697     fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
 698     operand: &Operand<'tcx>,
 699 ) -> CValue<'tcx> {
 700     match operand {
 701         Operand::Move(place) | Operand::Copy(place) => {
 702             let cplace = trans_place(fx, place);
 703             cplace.to_cvalue(fx)
 704         }
 705         Operand::Constant(const_) => crate::constant::trans_constant(fx, const_),
 706     }
 707 }