compiler/rustc_codegen_ssa/src/mir/rvalue.rs

   1 use super::operand::{OperandRef, OperandValue};
   2 use super::place::PlaceRef;
   3 use super::{FunctionCx, LocalRef};
   4
   5 use crate::base;
   6 use crate::common::{self, IntPredicate};
   7 use crate::meth::get_vtable;
   8 use crate::traits::*;
   9 use crate::MemFlags;
  10
  11 use rustc_middle::mir;
  12 use rustc_middle::mir::Operand;
  13 use rustc_middle::ty::cast::{CastTy, IntTy};
  14 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
  15 use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
  16 use rustc_span::source_map::{Span, DUMMY_SP};
  17 use rustc_target::abi::Size;
  18
  19 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
  20     #[instrument(level = "trace", skip(self, bx))]
  21     pub fn codegen_rvalue(
  22         &mut self,
  23         mut bx: Bx,
  24         dest: PlaceRef<'tcx, Bx::Value>,
  25         rvalue: &mir::Rvalue<'tcx>,
  26     ) -> Bx {
  27         match *rvalue {
  28             mir::Rvalue::Use(ref operand) => {
  29                 let cg_operand = self.codegen_operand(&mut bx, operand);
  30                 // FIXME: consider not copying constants through stack. (Fixable by codegen'ing
  31                 // constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?)
  32                 cg_operand.val.store(&mut bx, dest);
  33                 bx
  34             }
  35
  36             mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => {
  37                 // The destination necessarily contains a fat pointer, so if
  38                 // it's a scalar pair, it's a fat pointer or newtype thereof.
  39                 if bx.cx().is_backend_scalar_pair(dest.layout) {
  40                     // Into-coerce of a thin pointer to a fat pointer -- just
  41                     // use the operand path.
  42                     let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
  43                     temp.val.store(&mut bx, dest);
  44                     return bx;
  45                 }
  46
  47                 // Unsize of a nontrivial struct. I would prefer for
  48                 // this to be eliminated by MIR building, but
  49                 // `CoerceUnsized` can be passed by a where-clause,
  50                 // so the (generic) MIR may not be able to expand it.
  51                 let operand = self.codegen_operand(&mut bx, source);
  52                 match operand.val {
  53                     OperandValue::Pair(..) | OperandValue::Immediate(_) => {
  54                         // Unsize from an immediate structure. We don't
  55                         // really need a temporary alloca here, but
  56                         // avoiding it would require us to have
  57                         // `coerce_unsized_into` use `extractvalue` to
  58                         // index into the struct, and this case isn't
  59                         // important enough for it.
  60                         debug!("codegen_rvalue: creating ugly alloca");
  61                         let scratch = PlaceRef::alloca(&mut bx, operand.layout);
  62                         scratch.storage_live(&mut bx);
  63                         operand.val.store(&mut bx, scratch);
  64                         base::coerce_unsized_into(&mut bx, scratch, dest);
  65                         scratch.storage_dead(&mut bx);
  66                     }
  67                     OperandValue::Ref(llref, None, align) => {
  68                         let source = PlaceRef::new_sized_aligned(llref, operand.layout, align);
  69                         base::coerce_unsized_into(&mut bx, source, dest);
  70                     }
  71                     OperandValue::Ref(_, Some(_), _) => {
  72                         bug!("unsized coercion on an unsized rvalue");
  73                     }
  74                 }
  75                 bx
  76             }
  77
  78             mir::Rvalue::Repeat(ref elem, count) => {
  79                 let cg_elem = self.codegen_operand(&mut bx, elem);
  80
  81                 // Do not generate the loop for zero-sized elements or empty arrays.
  82                 if dest.layout.is_zst() {
  83                     return bx;
  84                 }
  85
  86                 if let OperandValue::Immediate(v) = cg_elem.val {
  87                     let zero = bx.const_usize(0);
  88                     let start = dest.project_index(&mut bx, zero).llval;
  89                     let size = bx.const_usize(dest.layout.size.bytes());
  90
  91                     // Use llvm.memset.p0i8.* to initialize all zero arrays
  92                     if bx.cx().const_to_opt_u128(v, false) == Some(0) {
  93                         let fill = bx.cx().const_u8(0);
  94                         bx.memset(start, fill, size, dest.align, MemFlags::empty());
  95                         return bx;
  96                     }
  97
  98                     // Use llvm.memset.p0i8.* to initialize byte arrays
  99                     let v = bx.from_immediate(v);
 100                     if bx.cx().val_ty(v) == bx.cx().type_i8() {
 101                         bx.memset(start, v, size, dest.align, MemFlags::empty());
 102                         return bx;
 103                     }
 104                 }
 105
 106                 let count =
 107                     self.monomorphize(count).eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
 108
 109                 bx.write_operand_repeatedly(cg_elem, count, dest)
 110             }
 111
 112             mir::Rvalue::Aggregate(ref kind, ref operands) => {
 113                 let (dest, active_field_index) = match **kind {
 114                     mir::AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => {
 115                         dest.codegen_set_discr(&mut bx, variant_index);
 116                         if bx.tcx().adt_def(adt_did).is_enum() {
 117                             (dest.project_downcast(&mut bx, variant_index), active_field_index)
 118                         } else {
 119                             (dest, active_field_index)
 120                         }
 121                     }
 122                     _ => (dest, None),
 123                 };
 124                 for (i, operand) in operands.iter().enumerate() {
 125                     let op = self.codegen_operand(&mut bx, operand);
 126                     // Do not generate stores and GEPis for zero-sized fields.
 127                     if !op.layout.is_zst() {
 128                         let field_index = active_field_index.unwrap_or(i);
 129                         let field = if let mir::AggregateKind::Array(_) = **kind {
 130                             let llindex = bx.cx().const_usize(field_index as u64);
 131                             dest.project_index(&mut bx, llindex)
 132                         } else {
 133                             dest.project_field(&mut bx, field_index)
 134                         };
 135                         op.val.store(&mut bx, field);
 136                     }
 137                 }
 138                 bx
 139             }
 140
 141             _ => {
 142                 assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP));
 143                 let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
 144                 temp.val.store(&mut bx, dest);
 145                 bx
 146             }
 147         }
 148     }
 149
 150     pub fn codegen_rvalue_unsized(
 151         &mut self,
 152         mut bx: Bx,
 153         indirect_dest: PlaceRef<'tcx, Bx::Value>,
 154         rvalue: &mir::Rvalue<'tcx>,
 155     ) -> Bx {
 156         debug!(
 157             "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
 158             indirect_dest.llval, rvalue
 159         );
 160
 161         match *rvalue {
 162             mir::Rvalue::Use(ref operand) => {
 163                 let cg_operand = self.codegen_operand(&mut bx, operand);
 164                 cg_operand.val.store_unsized(&mut bx, indirect_dest);
 165                 bx
 166             }
 167
 168             _ => bug!("unsized assignment other than `Rvalue::Use`"),
 169         }
 170     }
 171
 172     pub fn codegen_rvalue_operand(
 173         &mut self,
 174         mut bx: Bx,
 175         rvalue: &mir::Rvalue<'tcx>,
 176     ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
 177         assert!(
 178             self.rvalue_creates_operand(rvalue, DUMMY_SP),
 179             "cannot codegen {:?} to operand",
 180             rvalue,
 181         );
 182
 183         match *rvalue {
 184             mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
 185                 let operand = self.codegen_operand(&mut bx, source);
 186                 debug!("cast operand is {:?}", operand);
 187                 let cast = bx.cx().layout_of(self.monomorphize(mir_cast_ty));
 188
 189                 let val = match *kind {
 190                     mir::CastKind::PointerExposeAddress => {
 191                         assert!(bx.cx().is_backend_immediate(cast));
 192                         let llptr = operand.immediate();
 193                         let llcast_ty = bx.cx().immediate_backend_type(cast);
 194                         let lladdr = bx.ptrtoint(llptr, llcast_ty);
 195                         OperandValue::Immediate(lladdr)
 196                     }
 197                     mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => {
 198                         match *operand.layout.ty.kind() {
 199                             ty::FnDef(def_id, substs) => {
 200                                 let instance = ty::Instance::resolve_for_fn_ptr(
 201                                     bx.tcx(),
 202                                     ty::ParamEnv::reveal_all(),
 203                                     def_id,
 204                                     substs,
 205                                 )
 206                                 .unwrap()
 207                                 .polymorphize(bx.cx().tcx());
 208                                 OperandValue::Immediate(bx.get_fn_addr(instance))
 209                             }
 210                             _ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty),
 211                         }
 212                     }
 213                     mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => {
 214                         match *operand.layout.ty.kind() {
 215                             ty::Closure(def_id, substs) => {
 216                                 let instance = Instance::resolve_closure(
 217                                     bx.cx().tcx(),
 218                                     def_id,
 219                                     substs,
 220                                     ty::ClosureKind::FnOnce,
 221                                 )
 222                                 .expect("failed to normalize and resolve closure during codegen")
 223                                 .polymorphize(bx.cx().tcx());
 224                                 OperandValue::Immediate(bx.cx().get_fn_addr(instance))
 225                             }
 226                             _ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty),
 227                         }
 228                     }
 229                     mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
 230                         // This is a no-op at the LLVM level.
 231                         operand.val
 232                     }
 233                     mir::CastKind::Pointer(PointerCast::Unsize) => {
 234                         assert!(bx.cx().is_backend_scalar_pair(cast));
 235                         let (lldata, llextra) = match operand.val {
 236                             OperandValue::Pair(lldata, llextra) => {
 237                                 // unsize from a fat pointer -- this is a
 238                                 // "trait-object-to-supertrait" coercion.
 239                                 (lldata, Some(llextra))
 240                             }
 241                             OperandValue::Immediate(lldata) => {
 242                                 // "standard" unsize
 243                                 (lldata, None)
 244                             }
 245                             OperandValue::Ref(..) => {
 246                                 bug!("by-ref operand {:?} in `codegen_rvalue_operand`", operand);
 247                             }
 248                         };
 249                         let (lldata, llextra) =
 250                             base::unsize_ptr(&mut bx, lldata, operand.layout.ty, cast.ty, llextra);
 251                         OperandValue::Pair(lldata, llextra)
 252                     }
 253                     mir::CastKind::Pointer(PointerCast::MutToConstPointer)
 254                     | mir::CastKind::PtrToPtr
 255                         if bx.cx().is_backend_scalar_pair(operand.layout) =>
 256                     {
 257                         if let OperandValue::Pair(data_ptr, meta) = operand.val {
 258                             if bx.cx().is_backend_scalar_pair(cast) {
 259                                 let data_cast = bx.pointercast(
 260                                     data_ptr,
 261                                     bx.cx().scalar_pair_element_backend_type(cast, 0, true),
 262                                 );
 263                                 OperandValue::Pair(data_cast, meta)
 264                             } else {
 265                                 // cast to thin-ptr
 266                                 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
 267                                 // pointer-cast of that pointer to desired pointer type.
 268                                 let llcast_ty = bx.cx().immediate_backend_type(cast);
 269                                 let llval = bx.pointercast(data_ptr, llcast_ty);
 270                                 OperandValue::Immediate(llval)
 271                             }
 272                         } else {
 273                             bug!("unexpected non-pair operand");
 274                         }
 275                     }
 276                     mir::CastKind::DynStar => {
 277                         let data = match operand.val {
 278                             OperandValue::Ref(_, _, _) => todo!(),
 279                             OperandValue::Immediate(v) => v,
 280                             OperandValue::Pair(_, _) => todo!(),
 281                         };
 282                         let trait_ref =
 283                             if let ty::Dynamic(data, _, ty::DynStar) = cast.ty.kind() {
 284                                 data.principal()
 285                             } else {
 286                                 bug!("Only valid to do a DynStar cast into a DynStar type")
 287                             };
 288                         let vtable = get_vtable(bx.cx(), source.ty(self.mir, bx.tcx()), trait_ref);
 289                         let vtable = bx.pointercast(vtable, bx.cx().type_ptr_to(bx.cx().type_isize()));
 290                         // FIXME(dyn-star): this is probably not the best way to check if this is
 291                         // a pointer, and really we should ensure that the value is a suitable
 292                         // pointer earlier in the compilation process.
 293                         let data = match operand.layout.pointee_info_at(bx.cx(), Size::ZERO) {
 294                             Some(_) => bx.ptrtoint(data, bx.cx().type_isize()),
 295                             None => data,
 296                         };
 297                         OperandValue::Pair(data, vtable)
 298                     }
 299                     mir::CastKind::Pointer(
 300                         PointerCast::MutToConstPointer | PointerCast::ArrayToPointer,
 301                     )
 302                     | mir::CastKind::IntToInt
 303                     | mir::CastKind::FloatToInt
 304                     | mir::CastKind::FloatToFloat
 305                     | mir::CastKind::IntToFloat
 306                     | mir::CastKind::PtrToPtr
 307                     | mir::CastKind::FnPtrToPtr
 308
 309                     // Since int2ptr can have arbitrary integer types as input (so we have to do
 310                     // sign extension and all that), it is currently best handled in the same code
 311                     // path as the other integer-to-X casts.
 312                     | mir::CastKind::PointerFromExposedAddress => {
 313                         assert!(bx.cx().is_backend_immediate(cast));
 314                         let ll_t_out = bx.cx().immediate_backend_type(cast);
 315                         if operand.layout.abi.is_uninhabited() {
 316                             let val = OperandValue::Immediate(bx.cx().const_undef(ll_t_out));
 317                             return (bx, OperandRef { val, layout: cast });
 318                         }
 319                         let r_t_in =
 320                             CastTy::from_ty(operand.layout.ty).expect("bad input type for cast");
 321                         let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
 322                         let ll_t_in = bx.cx().immediate_backend_type(operand.layout);
 323                         let llval = operand.immediate();
 324
 325                         let newval = match (r_t_in, r_t_out) {
 326                             (CastTy::Int(i), CastTy::Int(_)) => {
 327                                 bx.intcast(llval, ll_t_out, i.is_signed())
 328                             }
 329                             (CastTy::Float, CastTy::Float) => {
 330                                 let srcsz = bx.cx().float_width(ll_t_in);
 331                                 let dstsz = bx.cx().float_width(ll_t_out);
 332                                 if dstsz > srcsz {
 333                                     bx.fpext(llval, ll_t_out)
 334                                 } else if srcsz > dstsz {
 335                                     bx.fptrunc(llval, ll_t_out)
 336                                 } else {
 337                                     llval
 338                                 }
 339                             }
 340                             (CastTy::Int(i), CastTy::Float) => {
 341                                 if i.is_signed() {
 342                                     bx.sitofp(llval, ll_t_out)
 343                                 } else {
 344                                     bx.uitofp(llval, ll_t_out)
 345                                 }
 346                             }
 347                             (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => {
 348                                 bx.pointercast(llval, ll_t_out)
 349                             }
 350                             (CastTy::Int(i), CastTy::Ptr(_)) => {
 351                                 let usize_llval =
 352                                     bx.intcast(llval, bx.cx().type_isize(), i.is_signed());
 353                                 bx.inttoptr(usize_llval, ll_t_out)
 354                             }
 355                             (CastTy::Float, CastTy::Int(IntTy::I)) => {
 356                                 bx.cast_float_to_int(true, llval, ll_t_out)
 357                             }
 358                             (CastTy::Float, CastTy::Int(_)) => {
 359                                 bx.cast_float_to_int(false, llval, ll_t_out)
 360                             }
 361                             _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty),
 362                         };
 363                         OperandValue::Immediate(newval)
 364                     }
 365                 };
 366                 (bx, OperandRef { val, layout: cast })
 367             }
 368
 369             mir::Rvalue::Ref(_, bk, place) => {
 370                 let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
 371                     tcx.mk_ref(
 372                         tcx.lifetimes.re_erased,
 373                         ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() },
 374                     )
 375                 };
 376                 self.codegen_place_to_pointer(bx, place, mk_ref)
 377             }
 378
 379             mir::Rvalue::CopyForDeref(place) => {
 380                 let operand = self.codegen_operand(&mut bx, &Operand::Copy(place));
 381                 (bx, operand)
 382             }
 383             mir::Rvalue::AddressOf(mutability, place) => {
 384                 let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
 385                     tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability })
 386                 };
 387                 self.codegen_place_to_pointer(bx, place, mk_ptr)
 388             }
 389
 390             mir::Rvalue::Len(place) => {
 391                 let size = self.evaluate_array_len(&mut bx, place);
 392                 let operand = OperandRef {
 393                     val: OperandValue::Immediate(size),
 394                     layout: bx.cx().layout_of(bx.tcx().types.usize),
 395                 };
 396                 (bx, operand)
 397             }
 398
 399             mir::Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
 400                 let lhs = self.codegen_operand(&mut bx, lhs);
 401                 let rhs = self.codegen_operand(&mut bx, rhs);
 402                 let llresult = match (lhs.val, rhs.val) {
 403                     (
 404                         OperandValue::Pair(lhs_addr, lhs_extra),
 405                         OperandValue::Pair(rhs_addr, rhs_extra),
 406                     ) => self.codegen_fat_ptr_binop(
 407                         &mut bx,
 408                         op,
 409                         lhs_addr,
 410                         lhs_extra,
 411                         rhs_addr,
 412                         rhs_extra,
 413                         lhs.layout.ty,
 414                     ),
 415
 416                     (OperandValue::Immediate(lhs_val), OperandValue::Immediate(rhs_val)) => {
 417                         self.codegen_scalar_binop(&mut bx, op, lhs_val, rhs_val, lhs.layout.ty)
 418                     }
 419
 420                     _ => bug!(),
 421                 };
 422                 let operand = OperandRef {
 423                     val: OperandValue::Immediate(llresult),
 424                     layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
 425                 };
 426                 (bx, operand)
 427             }
 428             mir::Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => {
 429                 let lhs = self.codegen_operand(&mut bx, lhs);
 430                 let rhs = self.codegen_operand(&mut bx, rhs);
 431                 let result = self.codegen_scalar_checked_binop(
 432                     &mut bx,
 433                     op,
 434                     lhs.immediate(),
 435                     rhs.immediate(),
 436                     lhs.layout.ty,
 437                 );
 438                 let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
 439                 let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]);
 440                 let operand = OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) };
 441
 442                 (bx, operand)
 443             }
 444
 445             mir::Rvalue::UnaryOp(op, ref operand) => {
 446                 let operand = self.codegen_operand(&mut bx, operand);
 447                 let lloperand = operand.immediate();
 448                 let is_float = operand.layout.ty.is_floating_point();
 449                 let llval = match op {
 450                     mir::UnOp::Not => bx.not(lloperand),
 451                     mir::UnOp::Neg => {
 452                         if is_float {
 453                             bx.fneg(lloperand)
 454                         } else {
 455                             bx.neg(lloperand)
 456                         }
 457                     }
 458                 };
 459                 (bx, OperandRef { val: OperandValue::Immediate(llval), layout: operand.layout })
 460             }
 461
 462             mir::Rvalue::Discriminant(ref place) => {
 463                 let discr_ty = rvalue.ty(self.mir, bx.tcx());
 464                 let discr_ty = self.monomorphize(discr_ty);
 465                 let discr = self
 466                     .codegen_place(&mut bx, place.as_ref())
 467                     .codegen_get_discr(&mut bx, discr_ty);
 468                 (
 469                     bx,
 470                     OperandRef {
 471                         val: OperandValue::Immediate(discr),
 472                         layout: self.cx.layout_of(discr_ty),
 473                     },
 474                 )
 475             }
 476
 477             mir::Rvalue::NullaryOp(null_op, ty) => {
 478                 let ty = self.monomorphize(ty);
 479                 assert!(bx.cx().type_is_sized(ty));
 480                 let layout = bx.cx().layout_of(ty);
 481                 let val = match null_op {
 482                     mir::NullOp::SizeOf => layout.size.bytes(),
 483                     mir::NullOp::AlignOf => layout.align.abi.bytes(),
 484                 };
 485                 let val = bx.cx().const_usize(val);
 486                 let tcx = self.cx.tcx();
 487                 (
 488                     bx,
 489                     OperandRef {
 490                         val: OperandValue::Immediate(val),
 491                         layout: self.cx.layout_of(tcx.types.usize),
 492                     },
 493                 )
 494             }
 495
 496             mir::Rvalue::ThreadLocalRef(def_id) => {
 497                 assert!(bx.cx().tcx().is_static(def_id));
 498                 let static_ = bx.get_static(def_id);
 499                 let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id));
 500                 let operand = OperandRef::from_immediate_or_packed_pair(&mut bx, static_, layout);
 501                 (bx, operand)
 502             }
 503             mir::Rvalue::Use(ref operand) => {
 504                 let operand = self.codegen_operand(&mut bx, operand);
 505                 (bx, operand)
 506             }
 507             mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => {
 508                 // According to `rvalue_creates_operand`, only ZST
 509                 // aggregate rvalues are allowed to be operands.
 510                 let ty = rvalue.ty(self.mir, self.cx.tcx());
 511                 let operand =
 512                     OperandRef::new_zst(&mut bx, self.cx.layout_of(self.monomorphize(ty)));
 513                 (bx, operand)
 514             }
 515             mir::Rvalue::ShallowInitBox(ref operand, content_ty) => {
 516                 let operand = self.codegen_operand(&mut bx, operand);
 517                 let lloperand = operand.immediate();
 518
 519                 let content_ty = self.monomorphize(content_ty);
 520                 let box_layout = bx.cx().layout_of(bx.tcx().mk_box(content_ty));
 521                 let llty_ptr = bx.cx().backend_type(box_layout);
 522
 523                 let val = bx.pointercast(lloperand, llty_ptr);
 524                 let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout };
 525                 (bx, operand)
 526             }
 527         }
 528     }
 529
 530     fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value {
 531         // ZST are passed as operands and require special handling
 532         // because codegen_place() panics if Local is operand.
 533         if let Some(index) = place.as_local() {
 534             if let LocalRef::Operand(Some(op)) = self.locals[index] {
 535                 if let ty::Array(_, n) = op.layout.ty.kind() {
 536                     let n = n.eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
 537                     return bx.cx().const_usize(n);
 538                 }
 539             }
 540         }
 541         // use common size calculation for non zero-sized types
 542         let cg_value = self.codegen_place(bx, place.as_ref());
 543         cg_value.len(bx.cx())
 544     }
 545
 546     /// Codegen an `Rvalue::AddressOf` or `Rvalue::Ref`
 547     fn codegen_place_to_pointer(
 548         &mut self,
 549         mut bx: Bx,
 550         place: mir::Place<'tcx>,
 551         mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>,
 552     ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
 553         let cg_place = self.codegen_place(&mut bx, place.as_ref());
 554
 555         let ty = cg_place.layout.ty;
 556
 557         // Note: places are indirect, so storing the `llval` into the
 558         // destination effectively creates a reference.
 559         let val = if !bx.cx().type_has_metadata(ty) {
 560             OperandValue::Immediate(cg_place.llval)
 561         } else {
 562             OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap())
 563         };
 564         (bx, OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) })
 565     }
 566
 567     pub fn codegen_scalar_binop(
 568         &mut self,
 569         bx: &mut Bx,
 570         op: mir::BinOp,
 571         lhs: Bx::Value,
 572         rhs: Bx::Value,
 573         input_ty: Ty<'tcx>,
 574     ) -> Bx::Value {
 575         let is_float = input_ty.is_floating_point();
 576         let is_signed = input_ty.is_signed();
 577         match op {
 578             mir::BinOp::Add => {
 579                 if is_float {
 580                     bx.fadd(lhs, rhs)
 581                 } else {
 582                     bx.add(lhs, rhs)
 583                 }
 584             }
 585             mir::BinOp::Sub => {
 586                 if is_float {
 587                     bx.fsub(lhs, rhs)
 588                 } else {
 589                     bx.sub(lhs, rhs)
 590                 }
 591             }
 592             mir::BinOp::Mul => {
 593                 if is_float {
 594                     bx.fmul(lhs, rhs)
 595                 } else {
 596                     bx.mul(lhs, rhs)
 597                 }
 598             }
 599             mir::BinOp::Div => {
 600                 if is_float {
 601                     bx.fdiv(lhs, rhs)
 602                 } else if is_signed {
 603                     bx.sdiv(lhs, rhs)
 604                 } else {
 605                     bx.udiv(lhs, rhs)
 606                 }
 607             }
 608             mir::BinOp::Rem => {
 609                 if is_float {
 610                     bx.frem(lhs, rhs)
 611                 } else if is_signed {
 612                     bx.srem(lhs, rhs)
 613                 } else {
 614                     bx.urem(lhs, rhs)
 615                 }
 616             }
 617             mir::BinOp::BitOr => bx.or(lhs, rhs),
 618             mir::BinOp::BitAnd => bx.and(lhs, rhs),
 619             mir::BinOp::BitXor => bx.xor(lhs, rhs),
 620             mir::BinOp::Offset => {
 621                 let pointee_type = input_ty
 622                     .builtin_deref(true)
 623                     .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
 624                     .ty;
 625                 let llty = bx.cx().backend_type(bx.cx().layout_of(pointee_type));
 626                 bx.inbounds_gep(llty, lhs, &[rhs])
 627             }
 628             mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
 629             mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
 630             mir::BinOp::Ne
 631             | mir::BinOp::Lt
 632             | mir::BinOp::Gt
 633             | mir::BinOp::Eq
 634             | mir::BinOp::Le
 635             | mir::BinOp::Ge => {
 636                 if is_float {
 637                     bx.fcmp(base::bin_op_to_fcmp_predicate(op.to_hir_binop()), lhs, rhs)
 638                 } else {
 639                     bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs)
 640                 }
 641             }
 642         }
 643     }
 644
 645     pub fn codegen_fat_ptr_binop(
 646         &mut self,
 647         bx: &mut Bx,
 648         op: mir::BinOp,
 649         lhs_addr: Bx::Value,
 650         lhs_extra: Bx::Value,
 651         rhs_addr: Bx::Value,
 652         rhs_extra: Bx::Value,
 653         _input_ty: Ty<'tcx>,
 654     ) -> Bx::Value {
 655         match op {
 656             mir::BinOp::Eq => {
 657                 let lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
 658                 let rhs = bx.icmp(IntPredicate::IntEQ, lhs_extra, rhs_extra);
 659                 bx.and(lhs, rhs)
 660             }
 661             mir::BinOp::Ne => {
 662                 let lhs = bx.icmp(IntPredicate::IntNE, lhs_addr, rhs_addr);
 663                 let rhs = bx.icmp(IntPredicate::IntNE, lhs_extra, rhs_extra);
 664                 bx.or(lhs, rhs)
 665             }
 666             mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => {
 667                 // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
 668                 let (op, strict_op) = match op {
 669                     mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT),
 670                     mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT),
 671                     mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT),
 672                     mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT),
 673                     _ => bug!(),
 674                 };
 675                 let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr);
 676                 let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
 677                 let and_rhs = bx.icmp(op, lhs_extra, rhs_extra);
 678                 let rhs = bx.and(and_lhs, and_rhs);
 679                 bx.or(lhs, rhs)
 680             }
 681             _ => {
 682                 bug!("unexpected fat ptr binop");
 683             }
 684         }
 685     }
 686
 687     pub fn codegen_scalar_checked_binop(
 688         &mut self,
 689         bx: &mut Bx,
 690         op: mir::BinOp,
 691         lhs: Bx::Value,
 692         rhs: Bx::Value,
 693         input_ty: Ty<'tcx>,
 694     ) -> OperandValue<Bx::Value> {
 695         // This case can currently arise only from functions marked
 696         // with #[rustc_inherit_overflow_checks] and inlined from
 697         // another crate (mostly core::num generic/#[inline] fns),
 698         // while the current crate doesn't use overflow checks.
 699         if !bx.cx().check_overflow() {
 700             let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
 701             return OperandValue::Pair(val, bx.cx().const_bool(false));
 702         }
 703
 704         let (val, of) = match op {
 705             // These are checked using intrinsics
 706             mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
 707                 let oop = match op {
 708                     mir::BinOp::Add => OverflowOp::Add,
 709                     mir::BinOp::Sub => OverflowOp::Sub,
 710                     mir::BinOp::Mul => OverflowOp::Mul,
 711                     _ => unreachable!(),
 712                 };
 713                 bx.checked_binop(oop, input_ty, lhs, rhs)
 714             }
 715             mir::BinOp::Shl | mir::BinOp::Shr => {
 716                 let lhs_llty = bx.cx().val_ty(lhs);
 717                 let rhs_llty = bx.cx().val_ty(rhs);
 718                 let invert_mask = common::shift_mask_val(bx, lhs_llty, rhs_llty, true);
 719                 let outer_bits = bx.and(rhs, invert_mask);
 720
 721                 let of = bx.icmp(IntPredicate::IntNE, outer_bits, bx.cx().const_null(rhs_llty));
 722                 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
 723
 724                 (val, of)
 725             }
 726             _ => bug!("Operator `{:?}` is not a checkable operator", op),
 727         };
 728
 729         OperandValue::Pair(val, of)
 730     }
 731 }
 732
 733 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 734     pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool {
 735         match *rvalue {
 736             mir::Rvalue::Ref(..) |
 737             mir::Rvalue::CopyForDeref(..) |
 738             mir::Rvalue::AddressOf(..) |
 739             mir::Rvalue::Len(..) |
 740             mir::Rvalue::Cast(..) | // (*)
 741             mir::Rvalue::ShallowInitBox(..) | // (*)
 742             mir::Rvalue::BinaryOp(..) |
 743             mir::Rvalue::CheckedBinaryOp(..) |
 744             mir::Rvalue::UnaryOp(..) |
 745             mir::Rvalue::Discriminant(..) |
 746             mir::Rvalue::NullaryOp(..) |
 747             mir::Rvalue::ThreadLocalRef(_) |
 748             mir::Rvalue::Use(..) => // (*)
 749                 true,
 750             mir::Rvalue::Repeat(..) |
 751             mir::Rvalue::Aggregate(..) => {
 752                 let ty = rvalue.ty(self.mir, self.cx.tcx());
 753                 let ty = self.monomorphize(ty);
 754                 self.cx.spanned_layout_of(ty, span).is_zst()
 755             }
 756         }
 757
 758         // (*) this is only true if the type is suitable
 759     }
 760 }