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::prelude::*;
  10
  11 pub(crate) fn codegen_fn<'tcx>(cx: &mut crate::CodegenCx<'_, 'tcx>, instance: Instance<'tcx>) {
  12     let tcx = cx.tcx;
  13
  14     let _inst_guard =
  15         crate::PrintOnPanic(|| format!("{:?} {}", instance, tcx.symbol_name(instance).name));
  16     debug_assert!(!instance.substs.needs_infer());
  17
  18     let mir = tcx.instance_mir(instance.def);
  19
  20     // Declare function
  21     let name = tcx.symbol_name(instance).name.to_string();
  22     let sig = get_function_sig(tcx, cx.module.isa().triple(), instance);
  23     let func_id = cx.module.declare_function(&name, Linkage::Local, &sig).unwrap();
  24
  25     cx.cached_context.clear();
  26
  27     // Make the FunctionBuilder
  28     let mut func_ctx = FunctionBuilderContext::new();
  29     let mut func = std::mem::replace(&mut cx.cached_context.func, Function::new());
  30     func.name = ExternalName::user(0, func_id.as_u32());
  31     func.signature = sig;
  32     func.collect_debug_info();
  33
  34     let mut bcx = FunctionBuilder::new(&mut func, &mut func_ctx);
  35
  36     // Predefine blocks
  37     let start_block = bcx.create_block();
  38     let block_map: IndexVec<BasicBlock, Block> =
  39         (0..mir.basic_blocks().len()).map(|_| bcx.create_block()).collect();
  40
  41     // Make FunctionCx
  42     let pointer_type = cx.module.target_config().pointer_type();
  43     let clif_comments = crate::pretty_clif::CommentWriter::new(tcx, instance);
  44
  45     let mut fx = FunctionCx {
  46         cx,
  47         tcx,
  48         pointer_type,
  49
  50         instance,
  51         mir,
  52         fn_abi: Some(FnAbi::of_instance(&RevealAllLayoutCx(tcx), instance, &[])),
  53
  54         bcx,
  55         block_map,
  56         local_map: IndexVec::with_capacity(mir.local_decls.len()),
  57         caller_location: None, // set by `codegen_fn_prelude`
  58         cold_blocks: EntitySet::new(),
  59
  60         clif_comments,
  61         source_info_set: indexmap::IndexSet::new(),
  62         next_ssa_var: 0,
  63
  64         inline_asm_index: 0,
  65     };
  66
  67     let arg_uninhabited = fx
  68         .mir
  69         .args_iter()
  70         .any(|arg| fx.layout_of(fx.monomorphize(&fx.mir.local_decls[arg].ty)).abi.is_uninhabited());
  71
  72     if !crate::constant::check_constants(&mut fx) {
  73         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  74         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  75         crate::trap::trap_unreachable(&mut fx, "compilation should have been aborted");
  76     } else if arg_uninhabited {
  77         fx.bcx.append_block_params_for_function_params(fx.block_map[START_BLOCK]);
  78         fx.bcx.switch_to_block(fx.block_map[START_BLOCK]);
  79         crate::trap::trap_unreachable(&mut fx, "function has uninhabited argument");
  80     } else {
  81         tcx.sess.time("codegen clif ir", || {
  82             tcx.sess
  83                 .time("codegen prelude", || crate::abi::codegen_fn_prelude(&mut fx, start_block));
  84             codegen_fn_content(&mut fx);
  85         });
  86     }
  87
  88     // Recover all necessary data from fx, before accessing func will prevent future access to it.
  89     let instance = fx.instance;
  90     let mut clif_comments = fx.clif_comments;
  91     let source_info_set = fx.source_info_set;
  92     let local_map = fx.local_map;
  93     let cold_blocks = fx.cold_blocks;
  94
  95     // Store function in context
  96     let context = &mut cx.cached_context;
  97     context.func = func;
  98
  99     crate::pretty_clif::write_clif_file(tcx, "unopt", None, instance, &context, &clif_comments);
 100
 101     // Verify function
 102     verify_func(tcx, &clif_comments, &context.func);
 103
 104     // Perform rust specific optimizations
 105     tcx.sess.time("optimize clif ir", || {
 106         crate::optimize::optimize_function(
 107             tcx,
 108             instance,
 109             context,
 110             &cold_blocks,
 111             &mut clif_comments,
 112         );
 113     });
 114
 115     // If the return block is not reachable, then the SSA builder may have inserted an `iconst.i128`
 116     // instruction, which doesn't have an encoding.
 117     context.compute_cfg();
 118     context.compute_domtree();
 119     context.eliminate_unreachable_code(cx.module.isa()).unwrap();
 120     context.dce(cx.module.isa()).unwrap();
 121     // Some Cranelift optimizations expect the domtree to not yet be computed and as such don't
 122     // invalidate it when it would change.
 123     context.domtree.clear();
 124
 125     context.want_disasm = crate::pretty_clif::should_write_ir(tcx);
 126
 127     // Define function
 128     let module = &mut cx.module;
 129     tcx.sess.time("define function", || {
 130         module
 131             .define_function(func_id, context, &mut NullTrapSink {}, &mut NullStackMapSink {})
 132             .unwrap()
 133     });
 134
 135     // Write optimized function to file for debugging
 136     crate::pretty_clif::write_clif_file(
 137         tcx,
 138         "opt",
 139         Some(cx.module.isa()),
 140         instance,
 141         &context,
 142         &clif_comments,
 143     );
 144
 145     if let Some(disasm) = &context.mach_compile_result.as_ref().unwrap().disasm {
 146         crate::pretty_clif::write_ir_file(
 147             tcx,
 148             &format!("{}.vcode", tcx.symbol_name(instance).name),
 149             |file| file.write_all(disasm.as_bytes()),
 150         )
 151     }
 152
 153     // Define debuginfo for function
 154     let isa = cx.module.isa();
 155     let debug_context = &mut cx.debug_context;
 156     let unwind_context = &mut cx.unwind_context;
 157     tcx.sess.time("generate debug info", || {
 158         if let Some(debug_context) = debug_context {
 159             debug_context.define_function(
 160                 instance,
 161                 func_id,
 162                 &name,
 163                 isa,
 164                 context,
 165                 &source_info_set,
 166                 local_map,
 167             );
 168         }
 169         unwind_context.add_function(func_id, &context, isa);
 170     });
 171
 172     // Clear context to make it usable for the next function
 173     context.clear();
 174 }
 175
 176 pub(crate) fn verify_func(
 177     tcx: TyCtxt<'_>,
 178     writer: &crate::pretty_clif::CommentWriter,
 179     func: &Function,
 180 ) {
 181     tcx.sess.time("verify clif ir", || {
 182         let flags = cranelift_codegen::settings::Flags::new(cranelift_codegen::settings::builder());
 183         match cranelift_codegen::verify_function(&func, &flags) {
 184             Ok(_) => {}
 185             Err(err) => {
 186                 tcx.sess.err(&format!("{:?}", err));
 187                 let pretty_error = cranelift_codegen::print_errors::pretty_verifier_error(
 188                     &func,
 189                     None,
 190                     Some(Box::new(writer)),
 191                     err,
 192                 );
 193                 tcx.sess.fatal(&format!("cranelift verify error:\n{}", pretty_error));
 194             }
 195         }
 196     });
 197 }
 198
 199 fn codegen_fn_content(fx: &mut FunctionCx<'_, '_, '_>) {
 200     for (bb, bb_data) in fx.mir.basic_blocks().iter_enumerated() {
 201         let block = fx.get_block(bb);
 202         fx.bcx.switch_to_block(block);
 203
 204         if bb_data.is_cleanup {
 205             // Unwinding after panicking is not supported
 206             continue;
 207
 208             // FIXME once unwinding is supported uncomment next lines
 209             // // Unwinding is unlikely to happen, so mark cleanup block's as cold.
 210             // fx.cold_blocks.insert(block);
 211         }
 212
 213         fx.bcx.ins().nop();
 214         for stmt in &bb_data.statements {
 215             fx.set_debug_loc(stmt.source_info);
 216             codegen_stmt(fx, block, stmt);
 217         }
 218
 219         if fx.clif_comments.enabled() {
 220             let mut terminator_head = "\n".to_string();
 221             bb_data.terminator().kind.fmt_head(&mut terminator_head).unwrap();
 222             let inst = fx.bcx.func.layout.last_inst(block).unwrap();
 223             fx.add_comment(inst, terminator_head);
 224         }
 225
 226         fx.set_debug_loc(bb_data.terminator().source_info);
 227
 228         match &bb_data.terminator().kind {
 229             TerminatorKind::Goto { target } => {
 230                 if let TerminatorKind::Return = fx.mir[*target].terminator().kind {
 231                     let mut can_immediately_return = true;
 232                     for stmt in &fx.mir[*target].statements {
 233                         if let StatementKind::StorageDead(_) = stmt.kind {
 234                         } else {
 235                             // FIXME Can sometimes happen, see rust-lang/rust#70531
 236                             can_immediately_return = false;
 237                             break;
 238                         }
 239                     }
 240
 241                     if can_immediately_return {
 242                         crate::abi::codegen_return(fx);
 243                         continue;
 244                     }
 245                 }
 246
 247                 let block = fx.get_block(*target);
 248                 fx.bcx.ins().jump(block, &[]);
 249             }
 250             TerminatorKind::Return => {
 251                 crate::abi::codegen_return(fx);
 252             }
 253             TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
 254                 if !fx.tcx.sess.overflow_checks() {
 255                     if let mir::AssertKind::OverflowNeg(_) = *msg {
 256                         let target = fx.get_block(*target);
 257                         fx.bcx.ins().jump(target, &[]);
 258                         continue;
 259                     }
 260                 }
 261                 let cond = codegen_operand(fx, cond).load_scalar(fx);
 262
 263                 let target = fx.get_block(*target);
 264                 let failure = fx.bcx.create_block();
 265                 fx.cold_blocks.insert(failure);
 266
 267                 if *expected {
 268                     fx.bcx.ins().brz(cond, failure, &[]);
 269                 } else {
 270                     fx.bcx.ins().brnz(cond, failure, &[]);
 271                 };
 272                 fx.bcx.ins().jump(target, &[]);
 273
 274                 fx.bcx.switch_to_block(failure);
 275                 fx.bcx.ins().nop();
 276
 277                 match msg {
 278                     AssertKind::BoundsCheck { ref len, ref index } => {
 279                         let len = codegen_operand(fx, len).load_scalar(fx);
 280                         let index = codegen_operand(fx, index).load_scalar(fx);
 281                         let location = fx
 282                             .get_caller_location(bb_data.terminator().source_info.span)
 283                             .load_scalar(fx);
 284
 285                         codegen_panic_inner(
 286                             fx,
 287                             rustc_hir::LangItem::PanicBoundsCheck,
 288                             &[index, len, location],
 289                             bb_data.terminator().source_info.span,
 290                         );
 291                     }
 292                     _ => {
 293                         let msg_str = msg.description();
 294                         codegen_panic(fx, msg_str, bb_data.terminator().source_info.span);
 295                     }
 296                 }
 297             }
 298
 299             TerminatorKind::SwitchInt { discr, switch_ty, targets } => {
 300                 let discr = codegen_operand(fx, discr).load_scalar(fx);
 301
 302                 let use_bool_opt = switch_ty.kind() == fx.tcx.types.bool.kind()
 303                     || (targets.iter().count() == 1 && targets.iter().next().unwrap().0 == 0);
 304                 if use_bool_opt {
 305                     assert_eq!(targets.iter().count(), 1);
 306                     let (then_value, then_block) = targets.iter().next().unwrap();
 307                     let then_block = fx.get_block(then_block);
 308                     let else_block = fx.get_block(targets.otherwise());
 309                     let test_zero = match then_value {
 310                         0 => true,
 311                         1 => false,
 312                         _ => unreachable!("{:?}", targets),
 313                     };
 314
 315                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 316                     let (discr, is_inverted) =
 317                         crate::optimize::peephole::maybe_unwrap_bool_not(&mut fx.bcx, discr);
 318                     let test_zero = if is_inverted { !test_zero } else { test_zero };
 319                     let discr = crate::optimize::peephole::maybe_unwrap_bint(&mut fx.bcx, discr);
 320                     let discr =
 321                         crate::optimize::peephole::make_branchable_value(&mut fx.bcx, discr);
 322                     if let Some(taken) = crate::optimize::peephole::maybe_known_branch_taken(
 323                         &fx.bcx, discr, test_zero,
 324                     ) {
 325                         if taken {
 326                             fx.bcx.ins().jump(then_block, &[]);
 327                         } else {
 328                             fx.bcx.ins().jump(else_block, &[]);
 329                         }
 330                     } else {
 331                         if test_zero {
 332                             fx.bcx.ins().brz(discr, then_block, &[]);
 333                             fx.bcx.ins().jump(else_block, &[]);
 334                         } else {
 335                             fx.bcx.ins().brnz(discr, then_block, &[]);
 336                             fx.bcx.ins().jump(else_block, &[]);
 337                         }
 338                     }
 339                 } else {
 340                     let mut switch = ::cranelift_frontend::Switch::new();
 341                     for (value, block) in targets.iter() {
 342                         let block = fx.get_block(block);
 343                         switch.set_entry(value, block);
 344                     }
 345                     let otherwise_block = fx.get_block(targets.otherwise());
 346                     switch.emit(&mut fx.bcx, discr, otherwise_block);
 347                 }
 348             }
 349             TerminatorKind::Call {
 350                 func,
 351                 args,
 352                 destination,
 353                 fn_span,
 354                 cleanup: _,
 355                 from_hir_call: _,
 356             } => {
 357                 fx.tcx.sess.time("codegen call", || {
 358                     crate::abi::codegen_terminator_call(
 359                         fx,
 360                         *fn_span,
 361                         block,
 362                         func,
 363                         args,
 364                         *destination,
 365                     )
 366                 });
 367             }
 368             TerminatorKind::InlineAsm {
 369                 template,
 370                 operands,
 371                 options,
 372                 destination,
 373                 line_spans: _,
 374             } => {
 375                 crate::inline_asm::codegen_inline_asm(
 376                     fx,
 377                     bb_data.terminator().source_info.span,
 378                     template,
 379                     operands,
 380                     *options,
 381                 );
 382
 383                 match *destination {
 384                     Some(destination) => {
 385                         let destination_block = fx.get_block(destination);
 386                         fx.bcx.ins().jump(destination_block, &[]);
 387                     }
 388                     None => {
 389                         crate::trap::trap_unreachable(
 390                             fx,
 391                             "[corruption] Returned from noreturn inline asm",
 392                         );
 393                     }
 394                 }
 395             }
 396             TerminatorKind::Resume | TerminatorKind::Abort => {
 397                 trap_unreachable(fx, "[corruption] Unwinding bb reached.");
 398             }
 399             TerminatorKind::Unreachable => {
 400                 trap_unreachable(fx, "[corruption] Hit unreachable code.");
 401             }
 402             TerminatorKind::Yield { .. }
 403             | TerminatorKind::FalseEdge { .. }
 404             | TerminatorKind::FalseUnwind { .. }
 405             | TerminatorKind::DropAndReplace { .. }
 406             | TerminatorKind::GeneratorDrop => {
 407                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
 408             }
 409             TerminatorKind::Drop { place, target, unwind: _ } => {
 410                 let drop_place = codegen_place(fx, *place);
 411                 crate::abi::codegen_drop(fx, bb_data.terminator().source_info.span, drop_place);
 412
 413                 let target_block = fx.get_block(*target);
 414                 fx.bcx.ins().jump(target_block, &[]);
 415             }
 416         };
 417     }
 418
 419     fx.bcx.seal_all_blocks();
 420     fx.bcx.finalize();
 421 }
 422
 423 fn codegen_stmt<'tcx>(
 424     fx: &mut FunctionCx<'_, '_, 'tcx>,
 425     #[allow(unused_variables)] cur_block: Block,
 426     stmt: &Statement<'tcx>,
 427 ) {
 428     let _print_guard = crate::PrintOnPanic(|| format!("stmt {:?}", stmt));
 429
 430     fx.set_debug_loc(stmt.source_info);
 431
 432     #[cfg(disabled)]
 433     match &stmt.kind {
 434         StatementKind::StorageLive(..) | StatementKind::StorageDead(..) => {} // Those are not very useful
 435         _ => {
 436             if fx.clif_comments.enabled() {
 437                 let inst = fx.bcx.func.layout.last_inst(cur_block).unwrap();
 438                 fx.add_comment(inst, format!("{:?}", stmt));
 439             }
 440         }
 441     }
 442
 443     match &stmt.kind {
 444         StatementKind::SetDiscriminant { place, variant_index } => {
 445             let place = codegen_place(fx, **place);
 446             crate::discriminant::codegen_set_discriminant(fx, place, *variant_index);
 447         }
 448         StatementKind::Assign(to_place_and_rval) => {
 449             let lval = codegen_place(fx, to_place_and_rval.0);
 450             let dest_layout = lval.layout();
 451             match to_place_and_rval.1 {
 452                 Rvalue::Use(ref operand) => {
 453                     let val = codegen_operand(fx, operand);
 454                     lval.write_cvalue(fx, val);
 455                 }
 456                 Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
 457                     let place = codegen_place(fx, place);
 458                     let ref_ = place.place_ref(fx, lval.layout());
 459                     lval.write_cvalue(fx, ref_);
 460                 }
 461                 Rvalue::ThreadLocalRef(def_id) => {
 462                     let val = crate::constant::codegen_tls_ref(fx, def_id, lval.layout());
 463                     lval.write_cvalue(fx, val);
 464                 }
 465                 Rvalue::BinaryOp(bin_op, ref lhs_rhs) => {
 466                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 467                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 468
 469                     let res = crate::num::codegen_binop(fx, bin_op, lhs, rhs);
 470                     lval.write_cvalue(fx, res);
 471                 }
 472                 Rvalue::CheckedBinaryOp(bin_op, ref lhs_rhs) => {
 473                     let lhs = codegen_operand(fx, &lhs_rhs.0);
 474                     let rhs = codegen_operand(fx, &lhs_rhs.1);
 475
 476                     let res = if !fx.tcx.sess.overflow_checks() {
 477                         let val =
 478                             crate::num::codegen_int_binop(fx, bin_op, lhs, rhs).load_scalar(fx);
 479                         let is_overflow = fx.bcx.ins().iconst(types::I8, 0);
 480                         CValue::by_val_pair(val, is_overflow, lval.layout())
 481                     } else {
 482                         crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs)
 483                     };
 484
 485                     lval.write_cvalue(fx, res);
 486                 }
 487                 Rvalue::UnaryOp(un_op, ref operand) => {
 488                     let operand = codegen_operand(fx, operand);
 489                     let layout = operand.layout();
 490                     let val = operand.load_scalar(fx);
 491                     let res = match un_op {
 492                         UnOp::Not => match layout.ty.kind() {
 493                             ty::Bool => {
 494                                 let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
 495                                 CValue::by_val(fx.bcx.ins().bint(types::I8, res), layout)
 496                             }
 497                             ty::Uint(_) | ty::Int(_) => {
 498                                 CValue::by_val(fx.bcx.ins().bnot(val), layout)
 499                             }
 500                             _ => unreachable!("un op Not for {:?}", layout.ty),
 501                         },
 502                         UnOp::Neg => match layout.ty.kind() {
 503                             ty::Int(IntTy::I128) => {
 504                                 // FIXME remove this case once ineg.i128 works
 505                                 let zero =
 506                                     CValue::const_val(fx, layout, ty::ScalarInt::null(layout.size));
 507                                 crate::num::codegen_int_binop(fx, BinOp::Sub, zero, operand)
 508                             }
 509                             ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
 510                             ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
 511                             _ => unreachable!("un op Neg for {:?}", layout.ty),
 512                         },
 513                     };
 514                     lval.write_cvalue(fx, res);
 515                 }
 516                 Rvalue::Cast(
 517                     CastKind::Pointer(PointerCast::ReifyFnPointer),
 518                     ref operand,
 519                     to_ty,
 520                 ) => {
 521                     let from_ty = fx.monomorphize(operand.ty(&fx.mir.local_decls, fx.tcx));
 522                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 523                     match *from_ty.kind() {
 524                         ty::FnDef(def_id, substs) => {
 525                             let func_ref = fx.get_function_ref(
 526                                 Instance::resolve_for_fn_ptr(
 527                                     fx.tcx,
 528                                     ParamEnv::reveal_all(),
 529                                     def_id,
 530                                     substs,
 531                                 )
 532                                 .unwrap()
 533                                 .polymorphize(fx.tcx),
 534                             );
 535                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 536                             lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
 537                         }
 538                         _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
 539                     }
 540                 }
 541                 Rvalue::Cast(
 542                     CastKind::Pointer(PointerCast::UnsafeFnPointer),
 543                     ref operand,
 544                     to_ty,
 545                 )
 546                 | Rvalue::Cast(
 547                     CastKind::Pointer(PointerCast::MutToConstPointer),
 548                     ref operand,
 549                     to_ty,
 550                 )
 551                 | Rvalue::Cast(
 552                     CastKind::Pointer(PointerCast::ArrayToPointer),
 553                     ref operand,
 554                     to_ty,
 555                 ) => {
 556                     let to_layout = fx.layout_of(fx.monomorphize(to_ty));
 557                     let operand = codegen_operand(fx, operand);
 558                     lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
 559                 }
 560                 Rvalue::Cast(CastKind::Misc, ref operand, to_ty) => {
 561                     let operand = codegen_operand(fx, operand);
 562                     let from_ty = operand.layout().ty;
 563                     let to_ty = fx.monomorphize(to_ty);
 564
 565                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
 566                         ty.builtin_deref(true)
 567                             .map(|ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
 568                                 has_ptr_meta(fx.tcx, pointee_ty)
 569                             })
 570                             .unwrap_or(false)
 571                     }
 572
 573                     if is_fat_ptr(fx, from_ty) {
 574                         if is_fat_ptr(fx, to_ty) {
 575                             // fat-ptr -> fat-ptr
 576                             lval.write_cvalue(fx, operand.cast_pointer_to(dest_layout));
 577                         } else {
 578                             // fat-ptr -> thin-ptr
 579                             let (ptr, _extra) = operand.load_scalar_pair(fx);
 580                             lval.write_cvalue(fx, CValue::by_val(ptr, dest_layout))
 581                         }
 582                     } else if let ty::Adt(adt_def, _substs) = from_ty.kind() {
 583                         // enum -> discriminant value
 584                         assert!(adt_def.is_enum());
 585                         match to_ty.kind() {
 586                             ty::Uint(_) | ty::Int(_) => {}
 587                             _ => unreachable!("cast adt {} -> {}", from_ty, to_ty),
 588                         }
 589                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 590
 591                         let discriminant = crate::discriminant::codegen_get_discriminant(
 592                             fx,
 593                             operand,
 594                             fx.layout_of(operand.layout().ty.discriminant_ty(fx.tcx)),
 595                         )
 596                         .load_scalar(fx);
 597
 598                         let res = crate::cast::clif_intcast(
 599                             fx,
 600                             discriminant,
 601                             to_clif_ty,
 602                             to_ty.is_signed(),
 603                         );
 604                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 605                     } else {
 606                         let to_clif_ty = fx.clif_type(to_ty).unwrap();
 607                         let from = operand.load_scalar(fx);
 608
 609                         let res = clif_int_or_float_cast(
 610                             fx,
 611                             from,
 612                             type_sign(from_ty),
 613                             to_clif_ty,
 614                             type_sign(to_ty),
 615                         );
 616                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
 617                     }
 618                 }
 619                 Rvalue::Cast(
 620                     CastKind::Pointer(PointerCast::ClosureFnPointer(_)),
 621                     ref operand,
 622                     _to_ty,
 623                 ) => {
 624                     let operand = codegen_operand(fx, operand);
 625                     match *operand.layout().ty.kind() {
 626                         ty::Closure(def_id, substs) => {
 627                             let instance = Instance::resolve_closure(
 628                                 fx.tcx,
 629                                 def_id,
 630                                 substs,
 631                                 ty::ClosureKind::FnOnce,
 632                             )
 633                             .polymorphize(fx.tcx);
 634                             let func_ref = fx.get_function_ref(instance);
 635                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
 636                             lval.write_cvalue(fx, CValue::by_val(func_addr, lval.layout()));
 637                         }
 638                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
 639                     }
 640                 }
 641                 Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), ref operand, _to_ty) => {
 642                     let operand = codegen_operand(fx, operand);
 643                     operand.unsize_value(fx, lval);
 644                 }
 645                 Rvalue::Discriminant(place) => {
 646                     let place = codegen_place(fx, place);
 647                     let value = place.to_cvalue(fx);
 648                     let discr =
 649                         crate::discriminant::codegen_get_discriminant(fx, value, dest_layout);
 650                     lval.write_cvalue(fx, discr);
 651                 }
 652                 Rvalue::Repeat(ref operand, times) => {
 653                     let operand = codegen_operand(fx, operand);
 654                     let times = fx
 655                         .monomorphize(times)
 656                         .eval(fx.tcx, ParamEnv::reveal_all())
 657                         .val
 658                         .try_to_bits(fx.tcx.data_layout.pointer_size)
 659                         .unwrap();
 660                     if operand.layout().size.bytes() == 0 {
 661                         // Do nothing for ZST's
 662                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {
 663                         let times = fx.bcx.ins().iconst(fx.pointer_type, times as i64);
 664                         // FIXME use emit_small_memset where possible
 665                         let addr = lval.to_ptr().get_addr(fx);
 666                         let val = operand.load_scalar(fx);
 667                         fx.bcx.call_memset(fx.cx.module.target_config(), addr, val, times);
 668                     } else {
 669                         let loop_block = fx.bcx.create_block();
 670                         let loop_block2 = fx.bcx.create_block();
 671                         let done_block = fx.bcx.create_block();
 672                         let index = fx.bcx.append_block_param(loop_block, fx.pointer_type);
 673                         let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
 674                         fx.bcx.ins().jump(loop_block, &[zero]);
 675
 676                         fx.bcx.switch_to_block(loop_block);
 677                         let done = fx.bcx.ins().icmp_imm(IntCC::Equal, index, times as i64);
 678                         fx.bcx.ins().brnz(done, done_block, &[]);
 679                         fx.bcx.ins().jump(loop_block2, &[]);
 680
 681                         fx.bcx.switch_to_block(loop_block2);
 682                         let to = lval.place_index(fx, index);
 683                         to.write_cvalue(fx, operand);
 684                         let index = fx.bcx.ins().iadd_imm(index, 1);
 685                         fx.bcx.ins().jump(loop_block, &[index]);
 686
 687                         fx.bcx.switch_to_block(done_block);
 688                         fx.bcx.ins().nop();
 689                     }
 690                 }
 691                 Rvalue::Len(place) => {
 692                     let place = codegen_place(fx, place);
 693                     let usize_layout = fx.layout_of(fx.tcx.types.usize);
 694                     let len = codegen_array_len(fx, place);
 695                     lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
 696                 }
 697                 Rvalue::NullaryOp(NullOp::Box, content_ty) => {
 698                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
 699                     let content_ty = fx.monomorphize(content_ty);
 700                     let layout = fx.layout_of(content_ty);
 701                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
 702                     let llalign = fx.bcx.ins().iconst(usize_type, layout.align.abi.bytes() as i64);
 703                     let box_layout = fx.layout_of(fx.tcx.mk_box(content_ty));
 704
 705                     // Allocate space:
 706                     let def_id =
 707                         match fx.tcx.lang_items().require(rustc_hir::LangItem::ExchangeMalloc) {
 708                             Ok(id) => id,
 709                             Err(s) => {
 710                                 fx.tcx
 711                                     .sess
 712                                     .fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
 713                             }
 714                         };
 715                     let instance = ty::Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 716                     let func_ref = fx.get_function_ref(instance);
 717                     let call = fx.bcx.ins().call(func_ref, &[llsize, llalign]);
 718                     let ptr = fx.bcx.inst_results(call)[0];
 719                     lval.write_cvalue(fx, CValue::by_val(ptr, box_layout));
 720                 }
 721                 Rvalue::NullaryOp(NullOp::SizeOf, ty) => {
 722                     assert!(
 723                         lval.layout()
 724                             .ty
 725                             .is_sized(fx.tcx.at(stmt.source_info.span), ParamEnv::reveal_all())
 726                     );
 727                     let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
 728                     let val =
 729                         CValue::const_val(fx, fx.layout_of(fx.tcx.types.usize), ty_size.into());
 730                     lval.write_cvalue(fx, val);
 731                 }
 732                 Rvalue::Aggregate(ref kind, ref operands) => match kind.as_ref() {
 733                     AggregateKind::Array(_ty) => {
 734                         for (i, operand) in operands.iter().enumerate() {
 735                             let operand = codegen_operand(fx, operand);
 736                             let index = fx.bcx.ins().iconst(fx.pointer_type, i as i64);
 737                             let to = lval.place_index(fx, index);
 738                             to.write_cvalue(fx, operand);
 739                         }
 740                     }
 741                     _ => unreachable!("shouldn't exist at codegen {:?}", to_place_and_rval.1),
 742                 },
 743             }
 744         }
 745         StatementKind::StorageLive(_)
 746         | StatementKind::StorageDead(_)
 747         | StatementKind::Nop
 748         | StatementKind::FakeRead(..)
 749         | StatementKind::Retag { .. }
 750         | StatementKind::AscribeUserType(..) => {}
 751
 752         StatementKind::LlvmInlineAsm(asm) => {
 753             use rustc_span::symbol::Symbol;
 754             let LlvmInlineAsm { asm, outputs, inputs } = &**asm;
 755             let rustc_hir::LlvmInlineAsmInner {
 756                 asm: asm_code,         // Name
 757                 outputs: output_names, // Vec<LlvmInlineAsmOutput>
 758                 inputs: input_names,   // Vec<Name>
 759                 clobbers,              // Vec<Name>
 760                 volatile,              // bool
 761                 alignstack,            // bool
 762                 dialect: _,
 763                 asm_str_style: _,
 764             } = asm;
 765             match asm_code.as_str().trim() {
 766                 "" => {
 767                     // Black box
 768                 }
 769                 "mov %rbx, %rsi\n                  cpuid\n                  xchg %rbx, %rsi" => {
 770                     assert_eq!(input_names, &[Symbol::intern("{eax}"), Symbol::intern("{ecx}")]);
 771                     assert_eq!(output_names.len(), 4);
 772                     for (i, c) in (&["={eax}", "={esi}", "={ecx}", "={edx}"]).iter().enumerate() {
 773                         assert_eq!(&output_names[i].constraint.as_str(), c);
 774                         assert!(!output_names[i].is_rw);
 775                         assert!(!output_names[i].is_indirect);
 776                     }
 777
 778                     assert_eq!(clobbers, &[]);
 779
 780                     assert!(!volatile);
 781                     assert!(!alignstack);
 782
 783                     assert_eq!(inputs.len(), 2);
 784                     let leaf = codegen_operand(fx, &inputs[0].1).load_scalar(fx); // %eax
 785                     let subleaf = codegen_operand(fx, &inputs[1].1).load_scalar(fx); // %ecx
 786
 787                     let (eax, ebx, ecx, edx) =
 788                         crate::intrinsics::codegen_cpuid_call(fx, leaf, subleaf);
 789
 790                     assert_eq!(outputs.len(), 4);
 791                     codegen_place(fx, outputs[0])
 792                         .write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
 793                     codegen_place(fx, outputs[1])
 794                         .write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
 795                     codegen_place(fx, outputs[2])
 796                         .write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
 797                     codegen_place(fx, outputs[3])
 798                         .write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
 799                 }
 800                 "xgetbv" => {
 801                     assert_eq!(input_names, &[Symbol::intern("{ecx}")]);
 802
 803                     assert_eq!(output_names.len(), 2);
 804                     for (i, c) in (&["={eax}", "={edx}"]).iter().enumerate() {
 805                         assert_eq!(&output_names[i].constraint.as_str(), c);
 806                         assert!(!output_names[i].is_rw);
 807                         assert!(!output_names[i].is_indirect);
 808                     }
 809
 810                     assert_eq!(clobbers, &[]);
 811
 812                     assert!(!volatile);
 813                     assert!(!alignstack);
 814
 815                     crate::trap::trap_unimplemented(fx, "_xgetbv arch intrinsic is not supported");
 816                 }
 817                 // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
 818                 _ if fx.tcx.symbol_name(fx.instance).name.starts_with("___chkstk") => {
 819                     crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
 820                 }
 821                 _ if fx.tcx.symbol_name(fx.instance).name == "__alloca" => {
 822                     crate::trap::trap_unimplemented(fx, "Alloca is not supported");
 823                 }
 824                 // Used in sys::windows::abort_internal
 825                 "int $$0x29" => {
 826                     crate::trap::trap_unimplemented(fx, "Windows abort");
 827                 }
 828                 _ => fx
 829                     .tcx
 830                     .sess
 831                     .span_fatal(stmt.source_info.span, "Inline assembly is not supported"),
 832             }
 833         }
 834         StatementKind::Coverage { .. } => fx.tcx.sess.fatal("-Zcoverage is unimplemented"),
 835         StatementKind::CopyNonOverlapping(inner) => {
 836             let dst = codegen_operand(fx, &inner.dst);
 837             let pointee = dst
 838                 .layout()
 839                 .pointee_info_at(fx, rustc_target::abi::Size::ZERO)
 840                 .expect("Expected pointer");
 841             let dst = dst.load_scalar(fx);
 842             let src = codegen_operand(fx, &inner.src).load_scalar(fx);
 843             let count = codegen_operand(fx, &inner.count).load_scalar(fx);
 844             let elem_size: u64 = pointee.size.bytes();
 845             let bytes =
 846                 if elem_size != 1 { fx.bcx.ins().imul_imm(count, elem_size as i64) } else { count };
 847             fx.bcx.call_memcpy(fx.cx.module.target_config(), dst, src, bytes);
 848         }
 849     }
 850 }
 851
 852 fn codegen_array_len<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, place: CPlace<'tcx>) -> Value {
 853     match *place.layout().ty.kind() {
 854         ty::Array(_elem_ty, len) => {
 855             let len = fx.monomorphize(len).eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64;
 856             fx.bcx.ins().iconst(fx.pointer_type, len)
 857         }
 858         ty::Slice(_elem_ty) => {
 859             place.to_ptr_maybe_unsized().1.expect("Length metadata for slice place")
 860         }
 861         _ => bug!("Rvalue::Len({:?})", place),
 862     }
 863 }
 864
 865 pub(crate) fn codegen_place<'tcx>(
 866     fx: &mut FunctionCx<'_, '_, 'tcx>,
 867     place: Place<'tcx>,
 868 ) -> CPlace<'tcx> {
 869     let mut cplace = fx.get_local_place(place.local);
 870
 871     for elem in place.projection {
 872         match elem {
 873             PlaceElem::Deref => {
 874                 cplace = cplace.place_deref(fx);
 875             }
 876             PlaceElem::Field(field, _ty) => {
 877                 cplace = cplace.place_field(fx, field);
 878             }
 879             PlaceElem::Index(local) => {
 880                 let index = fx.get_local_place(local).to_cvalue(fx).load_scalar(fx);
 881                 cplace = cplace.place_index(fx, index);
 882             }
 883             PlaceElem::ConstantIndex { offset, min_length: _, from_end } => {
 884                 let offset: u64 = offset;
 885                 let index = if !from_end {
 886                     fx.bcx.ins().iconst(fx.pointer_type, offset as i64)
 887                 } else {
 888                     let len = codegen_array_len(fx, cplace);
 889                     fx.bcx.ins().iadd_imm(len, -(offset as i64))
 890                 };
 891                 cplace = cplace.place_index(fx, index);
 892             }
 893             PlaceElem::Subslice { from, to, from_end } => {
 894                 // These indices are generated by slice patterns.
 895                 // slice[from:-to] in Python terms.
 896
 897                 let from: u64 = from;
 898                 let to: u64 = to;
 899
 900                 match cplace.layout().ty.kind() {
 901                     ty::Array(elem_ty, _len) => {
 902                         assert!(!from_end, "array subslices are never `from_end`");
 903                         let elem_layout = fx.layout_of(elem_ty);
 904                         let ptr = cplace.to_ptr();
 905                         cplace = CPlace::for_ptr(
 906                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 907                             fx.layout_of(fx.tcx.mk_array(elem_ty, to - from)),
 908                         );
 909                     }
 910                     ty::Slice(elem_ty) => {
 911                         assert!(from_end, "slice subslices should be `from_end`");
 912                         let elem_layout = fx.layout_of(elem_ty);
 913                         let (ptr, len) = cplace.to_ptr_maybe_unsized();
 914                         let len = len.unwrap();
 915                         cplace = CPlace::for_ptr_with_extra(
 916                             ptr.offset_i64(fx, elem_layout.size.bytes() as i64 * (from as i64)),
 917                             fx.bcx.ins().iadd_imm(len, -(from as i64 + to as i64)),
 918                             cplace.layout(),
 919                         );
 920                     }
 921                     _ => unreachable!(),
 922                 }
 923             }
 924             PlaceElem::Downcast(_adt_def, variant) => {
 925                 cplace = cplace.downcast_variant(fx, variant);
 926             }
 927         }
 928     }
 929
 930     cplace
 931 }
 932
 933 pub(crate) fn codegen_operand<'tcx>(
 934     fx: &mut FunctionCx<'_, '_, 'tcx>,
 935     operand: &Operand<'tcx>,
 936 ) -> CValue<'tcx> {
 937     match operand {
 938         Operand::Move(place) | Operand::Copy(place) => {
 939             let cplace = codegen_place(fx, *place);
 940             cplace.to_cvalue(fx)
 941         }
 942         Operand::Constant(const_) => crate::constant::codegen_constant(fx, const_),
 943     }
 944 }
 945
 946 pub(crate) fn codegen_panic<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, msg_str: &str, span: Span) {
 947     let location = fx.get_caller_location(span).load_scalar(fx);
 948
 949     let msg_ptr = fx.anonymous_str("assert", msg_str);
 950     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
 951     let args = [msg_ptr, msg_len, location];
 952
 953     codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, span);
 954 }
 955
 956 pub(crate) fn codegen_panic_inner<'tcx>(
 957     fx: &mut FunctionCx<'_, '_, 'tcx>,
 958     lang_item: rustc_hir::LangItem,
 959     args: &[Value],
 960     span: Span,
 961 ) {
 962     let def_id =
 963         fx.tcx.lang_items().require(lang_item).unwrap_or_else(|s| fx.tcx.sess.span_fatal(span, &s));
 964
 965     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
 966     let symbol_name = fx.tcx.symbol_name(instance).name;
 967
 968     fx.lib_call(
 969         &*symbol_name,
 970         vec![
 971             AbiParam::new(fx.pointer_type),
 972             AbiParam::new(fx.pointer_type),
 973             AbiParam::new(fx.pointer_type),
 974         ],
 975         vec![],
 976         args,
 977     );
 978
 979     crate::trap::trap_unreachable(fx, "panic lang item returned");
 980 }