compiler/rustc_codegen_cranelift/src/base.rs

   1 //! Codegen of a single function
   2
   3 use cranelift_codegen::binemit::{NullStackMapSink, NullTrapSink};
   4 use rustc_index::vec::IndexVec;
   5 use rustc_middle::ty::adjustment::PointerCast;
   6 use rustc_middle::ty::layout::FnAbiExt;
   7 use rustc_target::abi::call::FnAbi;
   8
   9 use crate::constant::ConstantCx;
  10 use crate::prelude::*;
  11
  12 pub(crate) fn codegen_fn<'tcx>(
  13     cx: &mut crate::CodegenCx<'tcx>,
  14     module: &mut dyn Module,
  15     instance: Instance<'tcx>,
  16 ) {
  17     let tcx = cx.tcx;
  18
  19     let _inst_guard =
  20         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  21     debug_assert!(!instance.substs.needs_infer());
  22
  23     let mir = tcx.instance_mir(instance.def);
  24
  25     // Declare function
  26     let symbol_name = tcx.symbol_name(instance);
  27     let sig = get_function_sig(tcx, module.isa().triple(), instance);
  28     let func_id = module.declare_function(symbol_name.name, Linkage::Local, &sig).unwrap();
  29
  30     cx.cached_context.clear();
  31
  32     // Make the FunctionBuilder
  33     let mut func_ctx = FunctionBuilderContext::new();
  34     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  35     func.name = ExternalName::user(0, func_id.as_u32());
  36     func.signature = sig;
  37     func.collect_debug_info();
  38
  39     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  40
  41     // Predefine blocks
  42     let start_block = bcx.create_block();
  43     let block_map: IndexVec<BasicBlock, Block> =
  44         (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  45
  46     // Make FunctionCx
  47     let pointer_type = module.target_config().pointer_type();
  48     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  49
  50     let mut fx = FunctionCx {
  51         cx,
  52         module,
  53         tcx,
  54         pointer_type,
  55         vtables: FxHashMap::default(),
  56         constants_cx: ConstantCx::new(),
  57
  58         instance,
  59         symbol_name,
  60         mir,
  61         fn_abi: Some(FnAbi::of_instance(&RevealAllLayoutCx(tcx), instance, &[])),
  62
  63         bcx,
  64         block_map,
  65         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  66         caller_location: None, // set by `codegen_fn_prelude`
  67
  68         clif_comments,
  69         source_info_set: indexmap::IndexSet::new(),
  70         next_ssa_var: 0,
  71
  72         inline_asm_index: 0,
  73     };
  74
  75     let arg_uninhabited = fx
  76         .mir
  77         .args_iter()
  78         .any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  79
  80     if !crate::constant::check_constants(&mut fx) {
  81         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  82         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  83         crate::trap::trap_unreachable(&mut fx, "compilation should have been aborted");
  84     } else if arg_uninhabited {
  85         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  86         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  87         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  88     } else {
  89         tcx.sess.time("codegen clif ir", || {
  90             tcx.sess
  91                 .time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
  92             codegen_fn_content(&mut fx);
  93         });
  94     }
  95
  96     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  97     let instance = fx.instance;
  98     let mut clif_comments = fx.clif_comments;
  99     let source_info_set = fx.source_info_set;
 100     let local_map = fx.local_map;
 101
 102     fx.constants_cx.finalize(fx.tcx, &mut *fx.module);
 103
 104     // Store function in context
 105     let context = &mut cx.cached_context;
 106     context.func = func;
 107
 108     crate::pretty_clif::write_clif_file(tcx, "unopt", None, instance, &context, &clif_comments);
 109
 110     // Verify function
 111     verify_func(tcx, &clif_comments, &context.func);
 112
 113     // Perform rust specific optimizations
 114     tcx.sess.time("optimize clif ir", || {
 115         crate::optimize::optimize_function(tcx, instance, context, &mut clif_comments);
 116     });
 117
 118     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 119     // instruction, which doesn't have an encoding.
 120     context.compute_cfg();
 121     context.compute_domtree();
 122     context.eliminate_unreachable_code(module.isa()).unwrap();
 123     context.dce(module.isa()).unwrap();
 124     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 125     // invalidate it when it would change.
 126     context.domtree.clear();
 127
 128     context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 129
 130     // Define function
 131     tcx.sess.time("define function", || {
 132         module
 133             .define_function(func_id, context, &mut NullTrapSink {}, &mut NullStackMapSink {})
 134             .unwrap()
 135     });
 136
 137     // Write optimized function to file for debugging
 138     crate::pretty_clif::write_clif_file(
 139         tcx,
 140         "opt",
 141         Some(module.isa()),
 142         instance,
 143         &context,
 144         &clif_comments,
 145     );
 146
 147     if let Some(disasm) = &context.mach_compile_result.as_ref().unwrap().disasm {
 148         crate::pretty_clif::write_ir_file(
 149             tcx,
 150             || format!("{}.vcode", tcx.symbol_name(instance).name),
 151             |file| file.write_all(disasm.as_bytes()),
 152         )
 153     }
 154
 155     // Define debuginfo for function
 156     let isa = module.isa();
 157     let debug_context = &mut cx.debug_context;
 158     let unwind_context = &mut cx.unwind_context;
 159     tcx.sess.time("generate debug info", || {
 160         if let Some(debug_context) = debug_context {
 161             debug_context.define_function(
 162                 instance,
 163                 func_id,
 164                 symbol_name.name,
 165                 isa,
 166                 context,
 167                 &source_info_set,
 168                 local_map,
 169             );
 170         }
 171         unwind_context.add_function(func_id, &context, isa);
 172     });
 173
 174     // Clear context to make it usable for the next function
 175     context.clear();
 176 }
 177
 178 pub(crate) fn verify_func(
 179     tcx: TyCtxt<'_>,
 180     writer: &crate::pretty_clif::CommentWriter,
 181     func: &Function,
 182 ) {
 183     tcx.sess.time("verify clif ir", || {
 184         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 185         match cranelift_codegen::verify_function(&func, &flags) {
 186             Ok(_) => {}
 187             Err(err) => {
 188                 tcx.sess.err(&format!("{:?}", err));
 189                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 190                     &func,
 191                     None,
 192                     Some(Box::new(writer)),
 193                     err,
 194                 );
 195                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 196             }
 197         }
 198     });
 199 }
 200
 201 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, '_>) {
 202     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 203         let block = fx.get_block(bb);
 204         fx.bcx.switch_to_block(block);
 205
 206         if bb_data.is_cleanup {
 207             // Unwinding after panicking is not supported
 208             continue;
 209
 210             // FIXME Once unwinding is supported and Cranelift supports marking blocks as cold, do
 211             // so for cleanup blocks.
 212         }
 213
 214         fx.bcx.ins().nop();
 215         for stmt in &bb_data.statements {
 216             fx.set_debug_loc(stmt.source_info);
 217             codegen_stmt(fx, block, stmt);
 218         }
 219
 220         if fx.clif_comments.enabled() {
 221             let mut terminator_head = "\n".to_string();
 222             bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 223             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 224             fx.add_comment(inst, terminator_head);
 225         }
 226
 227         fx.set_debug_loc(bb_data.terminator().source_info);
 228
 229         match &bb_data.terminator().kind {
 230             TerminatorKind::Goto { target } => {
 231                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 232                     let mut can_immediately_return = true;
 233                     for stmt in &fx.mir[*target].statements {
 234                         if let StatementKind::StorageDead(_) = stmt.kind {
 235                         } else {
 236                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 237                             can_immediately_return = false;
 238                             break;
 239                         }
 240                     }
 241
 242                     if can_immediately_return {
 243                         crate::abi::codegen_return(fx);
 244                         continue;
 245                     }
 246                 }
 247
 248                 let block = fx.get_block(*target);
 249                 fx.bcx.ins().jump(block, &[]);
 250             }
 251             TerminatorKind::Return => {
 252                 crate::abi::codegen_return(fx);
 253             }
 254             TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
 255                 if !fx.tcx.sess.overflow_checks() {
 256                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 257                         let target = fx.get_block(*target);
 258                         fx.bcx.ins().jump(target, &[]);
 259                         continue;
 260                     }
 261                 }
 262                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 263
 264                 let target = fx.get_block(*target);
 265                 let failure = fx.bcx.create_block();
 266                 // FIXME Mark failure block as cold once Cranelift supports it
 267
 268                 if *expected {
 269                     fx.bcx.ins().brz(cond, failure, &[]);
 270                 } else {
 271                     fx.bcx.ins().brnz(cond, failure, &[]);
 272                 };
 273                 fx.bcx.ins().jump(target, &[]);
 274
 275                 fx.bcx.switch_to_block(failure);
 276                 fx.bcx.ins().nop();
 277
 278                 match msg {
 279                     AssertKind::BoundsCheck { ref len, ref index } => {
 280                         let len = codegen_operand(fx, len).load_scalar(fx);
 281                         let index = codegen_operand(fx, index).load_scalar(fx);
 282                         let location = fx
 283                             .get_caller_location(bb_data.terminator().source_info.span)
 284                             .load_scalar(fx);
 285
 286                         codegen_panic_inner(
 287                             fx,
 288                             rustc_hir::LangItem::PanicBoundsCheck,
 289                             &[index, len, location],
 290                             bb_data.terminator().source_info.span,
 291                         );
 292                     }
 293                     _ => {
 294                         let msg_str = msg.description();
 295                         codegen_panic(fx, msg_str, bb_data.terminator().source_info.span);
 296                     }
 297                 }
 298             }
 299
 300             TerminatorKind::SwitchInt { discr, switch_ty, targets } => {
 301                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 302
 303                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 304                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 305                 if use_bool_opt {
 306                     assert_eq!(targets.iter().count(), 1);
 307                     let (then_value, then_block) = targets.iter().next().unwrap();
 308                     let then_block = fx.get_block(then_block);
 309                     let else_block = fx.get_block(targets.otherwise());
 310                     let test_zero = match then_value {
 311                         0 => true,
 312                         1 => false,
 313                         _ => unreachable!("{:?}", targets),
 314                     };
 315
 316                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 317                     let (discr, is_inverted) =
 318                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 319                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 320                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 321                     let discr =
 322                         crate::optimize::peephole::make_branchable_value(&mut fx.bcx, discr);
 323                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 324                         &fx.bcx, discr, test_zero,
 325                     ) {
 326                         if taken {
 327                             fx.bcx.ins().jump(then_block, &[]);
 328                         } else {
 329                             fx.bcx.ins().jump(else_block, &[]);
 330                         }
 331                     } else {
 332                         if test_zero {
 333                             fx.bcx.ins().brz(discr, then_block, &[]);
 334                             fx.bcx.ins().jump(else_block, &[]);
 335                         } else {
 336                             fx.bcx.ins().brnz(discr, then_block, &[]);
 337                             fx.bcx.ins().jump(else_block, &[]);
 338                         }
 339                     }
 340                 } else {
 341                     let mut switch = ::cranelift_frontend::Switch::new();
 342                     for (value, block) in targets.iter() {
 343                         let block = fx.get_block(block);
 344                         switch.set_entry(value, block);
 345                     }
 346                     let otherwise_block = fx.get_block(targets.otherwise());
 347                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 348                 }
 349             }
 350             TerminatorKind::Call {
 351                 func,
 352                 args,
 353                 destination,
 354                 fn_span,
 355                 cleanup: _,
 356                 from_hir_call: _,
 357             } => {
 358                 fx.tcx.sess.time("codegen call", || {
 359                     crate::abi::codegen_terminator_call(fx, *fn_span, func, args, *destination)
 360                 });
 361             }
 362             TerminatorKind::InlineAsm {
 363                 template,
 364                 operands,
 365                 options,
 366                 destination,
 367                 line_spans: _,
 368             } => {
 369                 crate::inline_asm::codegen_inline_asm(
 370                     fx,
 371                     bb_data.terminator().source_info.span,
 372                     template,
 373                     operands,
 374                     *options,
 375                 );
 376
 377                 match *destination {
 378                     Some(destination) => {
 379                         let destination_block = fx.get_block(destination);
 380                         fx.bcx.ins().jump(destination_block, &[]);
 381                     }
 382                     None => {
 383                         crate::trap::trap_unreachable(
 384                             fx,
 385                             "[corruption] Returned from noreturn inline asm",
 386                         );
 387                     }
 388                 }
 389             }
 390             TerminatorKind::Resume | TerminatorKind::Abort => {
 391                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 392             }
 393             TerminatorKind::Unreachable => {
 394                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 395             }
 396             TerminatorKind::Yield { .. }
 397             | TerminatorKind::FalseEdge { .. }
 398             | TerminatorKind::FalseUnwind { .. }
 399             | TerminatorKind::DropAndReplace { .. }
 400             | TerminatorKind::GeneratorDrop => {
 401                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 402             }
 403             TerminatorKind::Drop { place, target, unwind: _ } => {
 404                 let drop_place = codegen_place(fx, *place);
 405                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 406
 407                 let target_block = fx.get_block(*target);
 408                 fx.bcx.ins().jump(target_block, &[]);
 409             }
 410         };
 411     }
 412
 413     fx.bcx.seal_all_blocks();
 414     fx.bcx.finalize();
 415 }
 416
 417 fn codegen_stmt<'tcx>(
 418     fx: &mut FunctionCx<'_, '_, 'tcx>,
 419     #[allow(unused_variables)] cur_block: Block,
 420     stmt: &Statement<'tcx>,
 421 ) {
 422     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 423
 424     fx.set_debug_loc(stmt.source_info);
 425
 426     #[cfg(disabled)]
 427     match &stmt.kind {
 428         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 429         _ => {
 430             if fx.clif_comments.enabled() {
 431                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 432                 fx.add_comment(inst, format!("{:?}", stmt));
 433             }
 434         }
 435     }
 436
 437     match &stmt.kind {
 438         StatementKind::SetDiscriminant { place, variant_index } => {
 439             let place = codegen_place(fx, **place);
 440             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 441         }
 442         StatementKind::Assign(to_place_and_rval) => {
 443             let lval = codegen_place(fx, to_place_and_rval.0);
 444             let dest_layout = lval.layout();
 445             match to_place_and_rval.1 {
 446                 Rvalue::Use(ref operand) => {
 447                     let val = codegen_operand(fx, operand);
 448                     lval.write_cvalue(fx, val);
 449                 }
 450                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 451                     let place = codegen_place(fx, place);
 452                     let ref_ = place.place_ref(fx, lval.layout());
 453                     lval.write_cvalue(fx, ref_);
 454                 }
 455                 Rvalue::ThreadLocalRef(def_id) => {
 456                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 457                     lval.write_cvalue(fx, val);
 458                 }
 459                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 460                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 461                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 462
 463                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 464                     lval.write_cvalue(fx, res);
 465                 }
 466                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 467                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 468                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 469
 470                     let res = if !fx.tcx.sess.overflow_checks() {
 471                         let val =
 472                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 473                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 474                         CValue::by_val_pair(val, is_overflow, lval.layout())
 475                     } else {
 476                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 477                     };
 478
 479                     lval.write_cvalue(fx, res);
 480                 }
 481                 Rvalue::UnaryOp(un_op, ref operand) => {
 482                     let operand = codegen_operand(fx, operand);
 483                     let layout = operand.layout();
 484                     let val = operand.load_scalar(fx);
 485                     let res = match un_op {
 486                         UnOp::Not => match layout.ty.kind() {
 487                             ty::Bool => {
 488                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 489                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 490                             }
 491                             ty::Uint(_) | ty::Int(_) => {
 492                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 493                             }
 494                             _ => unreachable!("un op Not for {:?}", layout.ty),
 495                         },
 496                         UnOp::Neg => match layout.ty.kind() {
 497                             ty::Int(IntTy::I128) => {
 498                                 // FIXME remove this case once ineg.i128 works
 499                                 let zero =
 500                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 501                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 502                             }
 503                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 504                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 505                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 506                         },
 507                     };
 508                     lval.write_cvalue(fx, res);
 509                 }
 510                 Rvalue::Cast(
 511                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 512                     ref operand,
 513                     to_ty,
 514                 ) => {
 515                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 516                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 517                     match *from_ty.kind() {
 518                         ty::FnDef(def_id, substs) => {
 519                             let func_ref = fx.get_function_ref(
 520                                 Instance::resolve_for_fn_ptr(
 521                                     fx.tcx,
 522                                     ParamEnv::reveal_all(),
 523                                     def_id,
 524                                     substs,
 525                                 )
 526                                 .unwrap()
 527                                 .polymorphize(fx.tcx),
 528                             );
 529                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 530                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 531                         }
 532                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 533                     }
 534                 }
 535                 Rvalue::Cast(
 536                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 537                     ref operand,
 538                     to_ty,
 539                 )
 540                 | Rvalue::Cast(
 541                     CastKind::Pointer(PointerCast::MutToConstPointer),
 542                     ref operand,
 543                     to_ty,
 544                 )
 545                 | Rvalue::Cast(
 546                     CastKind::Pointer(PointerCast::ArrayToPointer),
 547                     ref operand,
 548                     to_ty,
 549                 ) => {
 550                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 551                     let operand = codegen_operand(fx, operand);
 552                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 553                 }
 554                 Rvalue::Cast(CastKind::Misc, ref operand, to_ty) => {
 555                     let operand = codegen_operand(fx, operand);
 556                     let from_ty = operand.layout().ty;
 557                     let to_ty = fx.monomorphize(to_ty);
 558
 559                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 560                         ty.builtin_deref(true)
 561                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 562                                 has_ptr_meta(fx.tcx, pointee_ty)
 563                             })
 564                             .unwrap_or(false)
 565                     }
 566
 567                     if is_fat_ptr(fx, from_ty) {
 568                         if is_fat_ptr(fx, to_ty) {
 569                             // fat-ptr -> fat-ptr
 570                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 571                         } else {
 572                             // fat-ptr -> thin-ptr
 573                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 574                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 575                         }
 576                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 577                         // enum -> discriminant value
 578                         assert!(adt_def.is_enum());
 579                         match to_ty.kind() {
 580                             ty::Uint(_) | ty::Int(_) => {}
 581                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 582                         }
 583                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 584
 585                         let discriminant = crate::discriminant::codegen_get_discriminant(
 586                             fx,
 587                             operand,
 588                             fx.layout_of(operand.layout().ty.discriminant_ty(fx.tcx)),
 589                         )
 590                         .load_scalar(fx);
 591
 592                         let res = crate::cast::clif_intcast(
 593                             fx,
 594                             discriminant,
 595                             to_clif_ty,
 596                             to_ty.is_signed(),
 597                         );
 598                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 599                     } else {
 600                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 601                         let from = operand.load_scalar(fx);
 602
 603                         let res = clif_int_or_float_cast(
 604                             fx,
 605                             from,
 606                             type_sign(from_ty),
 607                             to_clif_ty,
 608                             type_sign(to_ty),
 609                         );
 610                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 611                     }
 612                 }
 613                 Rvalue::Cast(
 614                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 615                     ref operand,
 616                     _to_ty,
 617                 ) => {
 618                     let operand = codegen_operand(fx, operand);
 619                     match *operand.layout().ty.kind() {
 620                         ty::Closure(def_id, substs) => {
 621                             let instance = Instance::resolve_closure(
 622                                 fx.tcx,
 623                                 def_id,
 624                                 substs,
 625                                 ty::ClosureKind::FnOnce,
 626                             )
 627                             .polymorphize(fx.tcx);
 628                             let func_ref = fx.get_function_ref(instance);
 629                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 630                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 631                         }
 632                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 633                     }
 634                 }
 635                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 636                     let operand = codegen_operand(fx, operand);
 637                     operand.unsize_value(fx, lval);
 638                 }
 639                 Rvalue::Discriminant(place) => {
 640                     let place = codegen_place(fx, place);
 641                     let value = place.to_cvalue(fx);
 642                     let discr =
 643                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 644                     lval.write_cvalue(fx, discr);
 645                 }
 646                 Rvalue::Repeat(ref operand, times) => {
 647                     let operand = codegen_operand(fx, operand);
 648                     let times = fx
 649                         .monomorphize(times)
 650                         .eval(fx.tcx, ParamEnv::reveal_all())
 651                         .val
 652                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 653                         .unwrap();
 654                     if operand.layout().size.bytes() == 0 {
 655                         // Do nothing for ZST's
 656                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 657                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 658                         // FIXME use emit_small_memset where possible
 659                         let addr = lval.to_ptr().get_addr(fx);
 660                         let val = operand.load_scalar(fx);
 661                         fx.bcx.call_memset(fx.module.target_config(), addr, val, times);
 662                     } else {
 663                         let loop_block = fx.bcx.create_block();
 664                         let loop_block2 = fx.bcx.create_block();
 665                         let done_block = fx.bcx.create_block();
 666                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 667                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 668                         fx.bcx.ins().jump(loop_block, &[zero]);
 669
 670                         fx.bcx.switch_to_block(loop_block);
 671                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 672                         fx.bcx.ins().brnz(done, done_block, &[]);
 673                         fx.bcx.ins().jump(loop_block2, &[]);
 674
 675                         fx.bcx.switch_to_block(loop_block2);
 676                         let to = lval.place_index(fx, index);
 677                         to.write_cvalue(fx, operand);
 678                         let index = fx.bcx.ins().iadd_imm(index, 1);
 679                         fx.bcx.ins().jump(loop_block, &[index]);
 680
 681                         fx.bcx.switch_to_block(done_block);
 682                         fx.bcx.ins().nop();
 683                     }
 684                 }
 685                 Rvalue::Len(place) => {
 686                     let place = codegen_place(fx, place);
 687                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 688                     let len = codegen_array_len(fx, place);
 689                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 690                 }
 691                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 692                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 693                     let content_ty = fx.monomorphize(content_ty);
 694                     let layout = fx.layout_of(content_ty);
 695                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 696                     let llalign = fx.bcx.ins().iconst(usize_type, layout.align.abi.bytes() as i64);
 697                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 698
 699                     // Allocate space:
 700                     let def_id =
 701                         match fx.tcx.lang_items().require(rustc_hir::LangItem::ExchangeMalloc) {
 702                             Ok(id) => id,
 703                             Err(s) => {
 704                                 fx.tcx
 705                                     .sess
 706                                     .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 707                             }
 708                         };
 709                     let instance = ty::Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 710                     let func_ref = fx.get_function_ref(instance);
 711                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 712                     let ptr = fx.bcx.inst_results(call)[0];
 713                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 714                 }
 715                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 716                     assert!(
 717                         lval.layout()
 718                             .ty
 719                             .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all())
 720                     );
 721                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 722                     let val =
 723                         CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 724                     lval.write_cvalue(fx, val);
 725                 }
 726                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 727                     AggregateKind::Array(_ty) => {
 728                         for (i, operand) in operands.iter().enumerate() {
 729                             let operand = codegen_operand(fx, operand);
 730                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 731                             let to = lval.place_index(fx, index);
 732                             to.write_cvalue(fx, operand);
 733                         }
 734                     }
 735                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 736                 },
 737             }
 738         }
 739         StatementKind::StorageLive(_)
 740         | StatementKind::StorageDead(_)
 741         | StatementKind::Nop
 742         | StatementKind::FakeRead(..)
 743         | StatementKind::Retag { .. }
 744         | StatementKind::AscribeUserType(..) => {}
 745
 746         StatementKind::LlvmInlineAsm(asm) => {
 747             match asm.asm.asm.as_str().trim() {
 748                 "" => {
 749                     // Black box
 750                 }
 751                 _ => fx.tcx.sess.span_fatal(
 752                     stmt.source_info.span,
 753                     "Legacy `llvm_asm!` inline assembly is not supported. \
 754                     Try using the new `asm!` instead.",
 755                 ),
 756             }
 757         }
 758         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 759         StatementKind::CopyNonOverlapping(inner) => {
 760             let dst = codegen_operand(fx, &inner.dst);
 761             let pointee = dst
 762                 .layout()
 763                 .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 764                 .expect("Expected pointer");
 765             let dst = dst.load_scalar(fx);
 766             let src = codegen_operand(fx, &inner.src).load_scalar(fx);
 767             let count = codegen_operand(fx, &inner.count).load_scalar(fx);
 768             let elem_size: u64 = pointee.size.bytes();
 769             let bytes =
 770                 if elem_size != 1 { fx.bcx.ins().imul_imm(count, elem_size as i64) } else { count };
 771             fx.bcx.call_memcpy(fx.module.target_config(), dst, src, bytes);
 772         }
 773     }
 774 }
 775
 776 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 777     match *place.layout().ty.kind() {
 778         ty::Array(_elem_ty, len) => {
 779             let len = fx.monomorphize(len).eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 780             fx.bcx.ins().iconst(fx.pointer_type, len)
 781         }
 782         ty::Slice(_elem_ty) => {
 783             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 784         }
 785         _ => bug!("Rvalue::Len({:?})", place),
 786     }
 787 }
 788
 789 pub(crate) fn codegen_place<'tcx>(
 790     fx: &mut FunctionCx<'_, '_, 'tcx>,
 791     place: Place<'tcx>,
 792 ) -> CPlace<'tcx> {
 793     let mut cplace = fx.get_local_place(place.local);
 794
 795     for elem in place.projection {
 796         match elem {
 797             PlaceElem::Deref => {
 798                 cplace = cplace.place_deref(fx);
 799             }
 800             PlaceElem::Field(field, _ty) => {
 801                 cplace = cplace.place_field(fx, field);
 802             }
 803             PlaceElem::Index(local) => {
 804                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 805                 cplace = cplace.place_index(fx, index);
 806             }
 807             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 808                 let offset: u64 = offset;
 809                 let index = if !from_end {
 810                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 811                 } else {
 812                     let len = codegen_array_len(fx, cplace);
 813                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 814                 };
 815                 cplace = cplace.place_index(fx, index);
 816             }
 817             PlaceElem::Subslice { from, to, from_end } => {
 818                 // These indices are generated by slice patterns.
 819                 // slice[from:-to] in Python terms.
 820
 821                 let from: u64 = from;
 822                 let to: u64 = to;
 823
 824                 match cplace.layout().ty.kind() {
 825                     ty::Array(elem_ty, _len) => {
 826                         assert!(!from_end, "array subslices are never `from_end`");
 827                         let elem_layout = fx.layout_of(elem_ty);
 828                         let ptr = cplace.to_ptr();
 829                         cplace = CPlace::for_ptr(
 830                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 831                             fx.layout_of(fx.tcx.mk_array(elem_ty, to - from)),
 832                         );
 833                     }
 834                     ty::Slice(elem_ty) => {
 835                         assert!(from_end, "slice subslices should be `from_end`");
 836                         let elem_layout = fx.layout_of(elem_ty);
 837                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 838                         let len = len.unwrap();
 839                         cplace = CPlace::for_ptr_with_extra(
 840                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 841                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 842                             cplace.layout(),
 843                         );
 844                     }
 845                     _ => unreachable!(),
 846                 }
 847             }
 848             PlaceElem::Downcast(_adt_def, variant) => {
 849                 cplace = cplace.downcast_variant(fx, variant);
 850             }
 851         }
 852     }
 853
 854     cplace
 855 }
 856
 857 pub(crate) fn codegen_operand<'tcx>(
 858     fx: &mut FunctionCx<'_, '_, 'tcx>,
 859     operand: &Operand<'tcx>,
 860 ) -> CValue<'tcx> {
 861     match operand {
 862         Operand::Move(place) | Operand::Copy(place) => {
 863             let cplace = codegen_place(fx, *place);
 864             cplace.to_cvalue(fx)
 865         }
 866         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 867     }
 868 }
 869
 870 pub(crate) fn codegen_panic<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, msg_str: &str, span: Span) {
 871     let location = fx.get_caller_location(span).load_scalar(fx);
 872
 873     let msg_ptr = fx.anonymous_str("assert", msg_str);
 874     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 875     let args = [msg_ptr, msg_len, location];
 876
 877     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, span);
 878 }
 879
 880 pub(crate) fn codegen_panic_inner<'tcx>(
 881     fx: &mut FunctionCx<'_, '_, 'tcx>,
 882     lang_item: rustc_hir::LangItem,
 883     args: &[Value],
 884     span: Span,
 885 ) {
 886     let def_id =
 887         fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
 888
 889     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 890     let symbol_name = fx.tcx.symbol_name(instance).name;
 891
 892     fx.lib_call(
 893         &*symbol_name,
 894         vec![
 895             AbiParam::new(fx.pointer_type),
 896             AbiParam::new(fx.pointer_type),
 897             AbiParam::new(fx.pointer_type),
 898         ],
 899         vec![],
 900         args,
 901     );
 902
 903     crate::trap::trap_unreachable(fx, "panic lang item returned");
 904 }