compiler/rustc_codegen_cranelift/src/value_and_place.rs

   1 //! Definition of [`CValue`] and [`CPlace`]
   2
   3 use crate::prelude::*;
   4
   5 use cranelift_codegen::ir::immediates::Offset32;
   6
   7 fn codegen_field<'tcx>(
   8     fx: &mut FunctionCx<'_, '_, 'tcx>,
   9     base: Pointer,
  10     extra: Option<Value>,
  11     layout: TyAndLayout<'tcx>,
  12     field: mir::Field,
  13 ) -> (Pointer, TyAndLayout<'tcx>) {
  14     let field_offset = layout.fields.offset(field.index());
  15     let field_layout = layout.field(&*fx, field.index());
  16
  17     let simple = |fx: &mut FunctionCx<'_, '_, '_>| {
  18         (base.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap()), field_layout)
  19     };
  20
  21     if let Some(extra) = extra {
  22         if !field_layout.is_unsized() {
  23             return simple(fx);
  24         }
  25         match field_layout.ty.kind() {
  26             ty::Slice(..) | ty::Str | ty::Foreign(..) => simple(fx),
  27             ty::Adt(def, _) if def.repr().packed() => {
  28                 assert_eq!(layout.align.abi.bytes(), 1);
  29                 simple(fx)
  30             }
  31             _ => {
  32                 // We have to align the offset for DST's
  33                 let unaligned_offset = field_offset.bytes();
  34                 let (_, unsized_align) =
  35                     crate::unsize::size_and_align_of_dst(fx, field_layout, extra);
  36
  37                 let one = fx.bcx.ins().iconst(fx.pointer_type, 1);
  38                 let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
  39                 let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
  40                 let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
  41                 let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
  42                 let offset = fx.bcx.ins().band(and_lhs, and_rhs);
  43
  44                 (base.offset_value(fx, offset), field_layout)
  45             }
  46         }
  47     } else {
  48         simple(fx)
  49     }
  50 }
  51
  52 fn scalar_pair_calculate_b_offset(tcx: TyCtxt<'_>, a_scalar: Scalar, b_scalar: Scalar) -> Offset32 {
  53     let b_offset = a_scalar.size(&tcx).align_to(b_scalar.align(&tcx).abi);
  54     Offset32::new(b_offset.bytes().try_into().unwrap())
  55 }
  56
  57 /// A read-only value
  58 #[derive(Debug, Copy, Clone)]
  59 pub(crate) struct CValue<'tcx>(CValueInner, TyAndLayout<'tcx>);
  60
  61 #[derive(Debug, Copy, Clone)]
  62 enum CValueInner {
  63     ByRef(Pointer, Option<Value>),
  64     ByVal(Value),
  65     ByValPair(Value, Value),
  66 }
  67
  68 impl<'tcx> CValue<'tcx> {
  69     pub(crate) fn by_ref(ptr: Pointer, layout: TyAndLayout<'tcx>) -> CValue<'tcx> {
  70         CValue(CValueInner::ByRef(ptr, None), layout)
  71     }
  72
  73     pub(crate) fn by_ref_unsized(
  74         ptr: Pointer,
  75         meta: Value,
  76         layout: TyAndLayout<'tcx>,
  77     ) -> CValue<'tcx> {
  78         CValue(CValueInner::ByRef(ptr, Some(meta)), layout)
  79     }
  80
  81     pub(crate) fn by_val(value: Value, layout: TyAndLayout<'tcx>) -> CValue<'tcx> {
  82         CValue(CValueInner::ByVal(value), layout)
  83     }
  84
  85     pub(crate) fn by_val_pair(
  86         value: Value,
  87         extra: Value,
  88         layout: TyAndLayout<'tcx>,
  89     ) -> CValue<'tcx> {
  90         CValue(CValueInner::ByValPair(value, extra), layout)
  91     }
  92
  93     pub(crate) fn layout(&self) -> TyAndLayout<'tcx> {
  94         self.1
  95     }
  96
  97     // FIXME remove
  98     pub(crate) fn force_stack(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> (Pointer, Option<Value>) {
  99         let layout = self.1;
 100         match self.0 {
 101             CValueInner::ByRef(ptr, meta) => (ptr, meta),
 102             CValueInner::ByVal(_) | CValueInner::ByValPair(_, _) => {
 103                 let cplace = CPlace::new_stack_slot(fx, layout);
 104                 cplace.write_cvalue(fx, self);
 105                 (cplace.to_ptr(), None)
 106             }
 107         }
 108     }
 109
 110     pub(crate) fn try_to_ptr(self) -> Option<(Pointer, Option<Value>)> {
 111         match self.0 {
 112             CValueInner::ByRef(ptr, meta) => Some((ptr, meta)),
 113             CValueInner::ByVal(_) | CValueInner::ByValPair(_, _) => None,
 114         }
 115     }
 116
 117     /// Load a value with layout.abi of scalar
 118     pub(crate) fn load_scalar(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> Value {
 119         let layout = self.1;
 120         match self.0 {
 121             CValueInner::ByRef(ptr, None) => {
 122                 let clif_ty = match layout.abi {
 123                     Abi::Scalar(scalar) => scalar_to_clif_type(fx.tcx, scalar),
 124                     Abi::Vector { element, count } => scalar_to_clif_type(fx.tcx, element)
 125                         .by(u16::try_from(count).unwrap())
 126                         .unwrap(),
 127                     _ => unreachable!("{:?}", layout.ty),
 128                 };
 129                 let mut flags = MemFlags::new();
 130                 flags.set_notrap();
 131                 ptr.load(fx, clif_ty, flags)
 132             }
 133             CValueInner::ByVal(value) => value,
 134             CValueInner::ByRef(_, Some(_)) => bug!("load_scalar for unsized value not allowed"),
 135             CValueInner::ByValPair(_, _) => bug!("Please use load_scalar_pair for ByValPair"),
 136         }
 137     }
 138
 139     /// Load a value pair with layout.abi of scalar pair
 140     pub(crate) fn load_scalar_pair(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> (Value, Value) {
 141         let layout = self.1;
 142         match self.0 {
 143             CValueInner::ByRef(ptr, None) => {
 144                 let (a_scalar, b_scalar) = match layout.abi {
 145                     Abi::ScalarPair(a, b) => (a, b),
 146                     _ => unreachable!("load_scalar_pair({:?})", self),
 147                 };
 148                 let b_offset = scalar_pair_calculate_b_offset(fx.tcx, a_scalar, b_scalar);
 149                 let clif_ty1 = scalar_to_clif_type(fx.tcx, a_scalar);
 150                 let clif_ty2 = scalar_to_clif_type(fx.tcx, b_scalar);
 151                 let mut flags = MemFlags::new();
 152                 flags.set_notrap();
 153                 let val1 = ptr.load(fx, clif_ty1, flags);
 154                 let val2 = ptr.offset(fx, b_offset).load(fx, clif_ty2, flags);
 155                 (val1, val2)
 156             }
 157             CValueInner::ByRef(_, Some(_)) => {
 158                 bug!("load_scalar_pair for unsized value not allowed")
 159             }
 160             CValueInner::ByVal(_) => bug!("Please use load_scalar for ByVal"),
 161             CValueInner::ByValPair(val1, val2) => (val1, val2),
 162         }
 163     }
 164
 165     pub(crate) fn value_field(
 166         self,
 167         fx: &mut FunctionCx<'_, '_, 'tcx>,
 168         field: mir::Field,
 169     ) -> CValue<'tcx> {
 170         let layout = self.1;
 171         match self.0 {
 172             CValueInner::ByVal(val) => match layout.abi {
 173                 Abi::Vector { element: _, count } => {
 174                     let count = u8::try_from(count).expect("SIMD type with more than 255 lanes???");
 175                     let field = u8::try_from(field.index()).unwrap();
 176                     assert!(field < count);
 177                     let lane = fx.bcx.ins().extractlane(val, field);
 178                     let field_layout = layout.field(&*fx, usize::from(field));
 179                     CValue::by_val(lane, field_layout)
 180                 }
 181                 _ => unreachable!("value_field for ByVal with abi {:?}", layout.abi),
 182             },
 183             CValueInner::ByValPair(val1, val2) => match layout.abi {
 184                 Abi::ScalarPair(_, _) => {
 185                     let val = match field.as_u32() {
 186                         0 => val1,
 187                         1 => val2,
 188                         _ => bug!("field should be 0 or 1"),
 189                     };
 190                     let field_layout = layout.field(&*fx, usize::from(field));
 191                     CValue::by_val(val, field_layout)
 192                 }
 193                 _ => unreachable!("value_field for ByValPair with abi {:?}", layout.abi),
 194             },
 195             CValueInner::ByRef(ptr, None) => {
 196                 let (field_ptr, field_layout) = codegen_field(fx, ptr, None, layout, field);
 197                 CValue::by_ref(field_ptr, field_layout)
 198             }
 199             CValueInner::ByRef(_, Some(_)) => todo!(),
 200         }
 201     }
 202
 203     /// Like [`CValue::value_field`] except handling ADTs containing a single array field in a way
 204     /// such that you can access individual lanes.
 205     pub(crate) fn value_lane(
 206         self,
 207         fx: &mut FunctionCx<'_, '_, 'tcx>,
 208         lane_idx: u64,
 209     ) -> CValue<'tcx> {
 210         let layout = self.1;
 211         assert!(layout.ty.is_simd());
 212         let (lane_count, lane_ty) = layout.ty.simd_size_and_type(fx.tcx);
 213         let lane_layout = fx.layout_of(lane_ty);
 214         assert!(lane_idx < lane_count);
 215         match self.0 {
 216             CValueInner::ByVal(val) => match layout.abi {
 217                 Abi::Vector { element: _, count: _ } => {
 218                     assert!(lane_count <= u8::MAX.into(), "SIMD type with more than 255 lanes???");
 219                     let lane_idx = u8::try_from(lane_idx).unwrap();
 220                     let lane = fx.bcx.ins().extractlane(val, lane_idx);
 221                     CValue::by_val(lane, lane_layout)
 222                 }
 223                 _ => unreachable!("value_lane for ByVal with abi {:?}", layout.abi),
 224             },
 225             CValueInner::ByValPair(_, _) => unreachable!(),
 226             CValueInner::ByRef(ptr, None) => {
 227                 let field_offset = lane_layout.size * lane_idx;
 228                 let field_ptr = ptr.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap());
 229                 CValue::by_ref(field_ptr, lane_layout)
 230             }
 231             CValueInner::ByRef(_, Some(_)) => unreachable!(),
 232         }
 233     }
 234
 235     pub(crate) fn unsize_value(self, fx: &mut FunctionCx<'_, '_, 'tcx>, dest: CPlace<'tcx>) {
 236         crate::unsize::coerce_unsized_into(fx, self, dest);
 237     }
 238
 239     /// If `ty` is signed, `const_val` must already be sign extended.
 240     pub(crate) fn const_val(
 241         fx: &mut FunctionCx<'_, '_, 'tcx>,
 242         layout: TyAndLayout<'tcx>,
 243         const_val: ty::ScalarInt,
 244     ) -> CValue<'tcx> {
 245         assert_eq!(const_val.size(), layout.size, "{:#?}: {:?}", const_val, layout);
 246         use cranelift_codegen::ir::immediates::{Ieee32, Ieee64};
 247
 248         let clif_ty = fx.clif_type(layout.ty).unwrap();
 249
 250         if let ty::Bool = layout.ty.kind() {
 251             assert!(
 252                 const_val == ty::ScalarInt::FALSE || const_val == ty::ScalarInt::TRUE,
 253                 "Invalid bool 0x{:032X}",
 254                 const_val
 255             );
 256         }
 257
 258         let val = match layout.ty.kind() {
 259             ty::Uint(UintTy::U128) | ty::Int(IntTy::I128) => {
 260                 let const_val = const_val.to_bits(layout.size).unwrap();
 261                 let lsb = fx.bcx.ins().iconst(types::I64, const_val as u64 as i64);
 262                 let msb = fx.bcx.ins().iconst(types::I64, (const_val >> 64) as u64 as i64);
 263                 fx.bcx.ins().iconcat(lsb, msb)
 264             }
 265             ty::Bool | ty::Char | ty::Uint(_) | ty::Int(_) | ty::Ref(..) | ty::RawPtr(..) => {
 266                 fx.bcx.ins().iconst(clif_ty, const_val.to_bits(layout.size).unwrap() as i64)
 267             }
 268             ty::Float(FloatTy::F32) => {
 269                 fx.bcx.ins().f32const(Ieee32::with_bits(u32::try_from(const_val).unwrap()))
 270             }
 271             ty::Float(FloatTy::F64) => {
 272                 fx.bcx.ins().f64const(Ieee64::with_bits(u64::try_from(const_val).unwrap()))
 273             }
 274             _ => panic!(
 275                 "CValue::const_val for non bool/char/float/integer/pointer type {:?} is not allowed",
 276                 layout.ty
 277             ),
 278         };
 279
 280         CValue::by_val(val, layout)
 281     }
 282
 283     pub(crate) fn cast_pointer_to(self, layout: TyAndLayout<'tcx>) -> Self {
 284         assert!(matches!(self.layout().ty.kind(), ty::Ref(..) | ty::RawPtr(..) | ty::FnPtr(..)));
 285         assert!(matches!(layout.ty.kind(), ty::Ref(..) | ty::RawPtr(..) | ty::FnPtr(..)));
 286         assert_eq!(self.layout().abi, layout.abi);
 287         CValue(self.0, layout)
 288     }
 289 }
 290
 291 /// A place where you can write a value to or read a value from
 292 #[derive(Debug, Copy, Clone)]
 293 pub(crate) struct CPlace<'tcx> {
 294     inner: CPlaceInner,
 295     layout: TyAndLayout<'tcx>,
 296 }
 297
 298 #[derive(Debug, Copy, Clone)]
 299 pub(crate) enum CPlaceInner {
 300     Var(Local, Variable),
 301     VarPair(Local, Variable, Variable),
 302     VarLane(Local, Variable, u8),
 303     Addr(Pointer, Option<Value>),
 304 }
 305
 306 impl<'tcx> CPlace<'tcx> {
 307     pub(crate) fn layout(&self) -> TyAndLayout<'tcx> {
 308         self.layout
 309     }
 310
 311     pub(crate) fn inner(&self) -> &CPlaceInner {
 312         &self.inner
 313     }
 314
 315     pub(crate) fn new_stack_slot(
 316         fx: &mut FunctionCx<'_, '_, 'tcx>,
 317         layout: TyAndLayout<'tcx>,
 318     ) -> CPlace<'tcx> {
 319         assert!(!layout.is_unsized());
 320         if layout.size.bytes() == 0 {
 321             return CPlace {
 322                 inner: CPlaceInner::Addr(Pointer::dangling(layout.align.pref), None),
 323                 layout,
 324             };
 325         }
 326
 327         let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
 328             kind: StackSlotKind::ExplicitSlot,
 329             // FIXME Don't force the size to a multiple of 16 bytes once Cranelift gets a way to
 330             // specify stack slot alignment.
 331             size: (u32::try_from(layout.size.bytes()).unwrap() + 15) / 16 * 16,
 332         });
 333         CPlace { inner: CPlaceInner::Addr(Pointer::stack_slot(stack_slot), None), layout }
 334     }
 335
 336     pub(crate) fn new_var(
 337         fx: &mut FunctionCx<'_, '_, 'tcx>,
 338         local: Local,
 339         layout: TyAndLayout<'tcx>,
 340     ) -> CPlace<'tcx> {
 341         let var = Variable::with_u32(fx.next_ssa_var);
 342         fx.next_ssa_var += 1;
 343         fx.bcx.declare_var(var, fx.clif_type(layout.ty).unwrap());
 344         CPlace { inner: CPlaceInner::Var(local, var), layout }
 345     }
 346
 347     pub(crate) fn new_var_pair(
 348         fx: &mut FunctionCx<'_, '_, 'tcx>,
 349         local: Local,
 350         layout: TyAndLayout<'tcx>,
 351     ) -> CPlace<'tcx> {
 352         let var1 = Variable::with_u32(fx.next_ssa_var);
 353         fx.next_ssa_var += 1;
 354         let var2 = Variable::with_u32(fx.next_ssa_var);
 355         fx.next_ssa_var += 1;
 356
 357         let (ty1, ty2) = fx.clif_pair_type(layout.ty).unwrap();
 358         fx.bcx.declare_var(var1, ty1);
 359         fx.bcx.declare_var(var2, ty2);
 360         CPlace { inner: CPlaceInner::VarPair(local, var1, var2), layout }
 361     }
 362
 363     pub(crate) fn for_ptr(ptr: Pointer, layout: TyAndLayout<'tcx>) -> CPlace<'tcx> {
 364         CPlace { inner: CPlaceInner::Addr(ptr, None), layout }
 365     }
 366
 367     pub(crate) fn for_ptr_with_extra(
 368         ptr: Pointer,
 369         extra: Value,
 370         layout: TyAndLayout<'tcx>,
 371     ) -> CPlace<'tcx> {
 372         CPlace { inner: CPlaceInner::Addr(ptr, Some(extra)), layout }
 373     }
 374
 375     pub(crate) fn to_cvalue(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> CValue<'tcx> {
 376         let layout = self.layout();
 377         match self.inner {
 378             CPlaceInner::Var(_local, var) => {
 379                 let val = fx.bcx.use_var(var);
 380                 //fx.bcx.set_val_label(val, cranelift_codegen::ir::ValueLabel::new(var.index()));
 381                 CValue::by_val(val, layout)
 382             }
 383             CPlaceInner::VarPair(_local, var1, var2) => {
 384                 let val1 = fx.bcx.use_var(var1);
 385                 //fx.bcx.set_val_label(val1, cranelift_codegen::ir::ValueLabel::new(var1.index()));
 386                 let val2 = fx.bcx.use_var(var2);
 387                 //fx.bcx.set_val_label(val2, cranelift_codegen::ir::ValueLabel::new(var2.index()));
 388                 CValue::by_val_pair(val1, val2, layout)
 389             }
 390             CPlaceInner::VarLane(_local, var, lane) => {
 391                 let val = fx.bcx.use_var(var);
 392                 //fx.bcx.set_val_label(val, cranelift_codegen::ir::ValueLabel::new(var.index()));
 393                 let val = fx.bcx.ins().extractlane(val, lane);
 394                 CValue::by_val(val, layout)
 395             }
 396             CPlaceInner::Addr(ptr, extra) => {
 397                 if let Some(extra) = extra {
 398                     CValue::by_ref_unsized(ptr, extra, layout)
 399                 } else {
 400                     CValue::by_ref(ptr, layout)
 401                 }
 402             }
 403         }
 404     }
 405
 406     pub(crate) fn to_ptr(self) -> Pointer {
 407         match self.to_ptr_maybe_unsized() {
 408             (ptr, None) => ptr,
 409             (_, Some(_)) => bug!("Expected sized cplace, found {:?}", self),
 410         }
 411     }
 412
 413     pub(crate) fn to_ptr_maybe_unsized(self) -> (Pointer, Option<Value>) {
 414         match self.inner {
 415             CPlaceInner::Addr(ptr, extra) => (ptr, extra),
 416             CPlaceInner::Var(_, _)
 417             | CPlaceInner::VarPair(_, _, _)
 418             | CPlaceInner::VarLane(_, _, _) => bug!("Expected CPlace::Addr, found {:?}", self),
 419         }
 420     }
 421
 422     pub(crate) fn write_cvalue(self, fx: &mut FunctionCx<'_, '_, 'tcx>, from: CValue<'tcx>) {
 423         assert_assignable(fx, from.layout().ty, self.layout().ty);
 424
 425         self.write_cvalue_maybe_transmute(fx, from, "write_cvalue");
 426     }
 427
 428     pub(crate) fn write_cvalue_transmute(
 429         self,
 430         fx: &mut FunctionCx<'_, '_, 'tcx>,
 431         from: CValue<'tcx>,
 432     ) {
 433         self.write_cvalue_maybe_transmute(fx, from, "write_cvalue_transmute");
 434     }
 435
 436     fn write_cvalue_maybe_transmute(
 437         self,
 438         fx: &mut FunctionCx<'_, '_, 'tcx>,
 439         from: CValue<'tcx>,
 440         method: &'static str,
 441     ) {
 442         fn transmute_value<'tcx>(
 443             fx: &mut FunctionCx<'_, '_, 'tcx>,
 444             var: Variable,
 445             data: Value,
 446             dst_ty: Type,
 447         ) {
 448             let src_ty = fx.bcx.func.dfg.value_type(data);
 449             assert_eq!(
 450                 src_ty.bytes(),
 451                 dst_ty.bytes(),
 452                 "write_cvalue_transmute: {:?} -> {:?}",
 453                 src_ty,
 454                 dst_ty,
 455             );
 456             let data = match (src_ty, dst_ty) {
 457                 (_, _) if src_ty == dst_ty => data,
 458
 459                 // This is a `write_cvalue_transmute`.
 460                 (types::I32, types::F32)
 461                 | (types::F32, types::I32)
 462                 | (types::I64, types::F64)
 463                 | (types::F64, types::I64) => fx.bcx.ins().bitcast(dst_ty, data),
 464                 _ if src_ty.is_vector() && dst_ty.is_vector() => {
 465                     fx.bcx.ins().raw_bitcast(dst_ty, data)
 466                 }
 467                 _ if src_ty.is_vector() || dst_ty.is_vector() => {
 468                     // FIXME do something more efficient for transmutes between vectors and integers.
 469                     let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
 470                         kind: StackSlotKind::ExplicitSlot,
 471                         // FIXME Don't force the size to a multiple of 16 bytes once Cranelift gets a way to
 472                         // specify stack slot alignment.
 473                         size: (src_ty.bytes() + 15) / 16 * 16,
 474                     });
 475                     let ptr = Pointer::stack_slot(stack_slot);
 476                     ptr.store(fx, data, MemFlags::trusted());
 477                     ptr.load(fx, dst_ty, MemFlags::trusted())
 478                 }
 479
 480                 // `CValue`s should never contain SSA-only types, so if you ended
 481                 // up here having seen an error like `B1 -> I8`, then before
 482                 // calling `write_cvalue` you need to add a `bint` instruction.
 483                 _ => unreachable!("write_cvalue_transmute: {:?} -> {:?}", src_ty, dst_ty),
 484             };
 485             //fx.bcx.set_val_label(data, cranelift_codegen::ir::ValueLabel::new(var.index()));
 486             fx.bcx.def_var(var, data);
 487         }
 488
 489         assert_eq!(self.layout().size, from.layout().size);
 490
 491         if fx.clif_comments.enabled() {
 492             use cranelift_codegen::cursor::{Cursor, CursorPosition};
 493             let cur_block = match fx.bcx.cursor().position() {
 494                 CursorPosition::After(block) => block,
 495                 _ => unreachable!(),
 496             };
 497             fx.add_comment(
 498                 fx.bcx.func.layout.last_inst(cur_block).unwrap(),
 499                 format!(
 500                     "{}: {:?}: {:?} <- {:?}: {:?}",
 501                     method,
 502                     self.inner(),
 503                     self.layout().ty,
 504                     from.0,
 505                     from.layout().ty
 506                 ),
 507             );
 508         }
 509
 510         let dst_layout = self.layout();
 511         let to_ptr = match self.inner {
 512             CPlaceInner::Var(_local, var) => {
 513                 if let ty::Array(element, len) = dst_layout.ty.kind() {
 514                     // Can only happen for vector types
 515                     let len =
 516                         u16::try_from(len.eval_usize(fx.tcx, ParamEnv::reveal_all())).unwrap();
 517                     let vector_ty = fx.clif_type(*element).unwrap().by(len).unwrap();
 518
 519                     let data = match from.0 {
 520                         CValueInner::ByRef(ptr, None) => {
 521                             let mut flags = MemFlags::new();
 522                             flags.set_notrap();
 523                             ptr.load(fx, vector_ty, flags)
 524                         }
 525                         CValueInner::ByVal(_)
 526                         | CValueInner::ByValPair(_, _)
 527                         | CValueInner::ByRef(_, Some(_)) => bug!("array should be ByRef"),
 528                     };
 529
 530                     fx.bcx.def_var(var, data);
 531                     return;
 532                 }
 533                 let data = CValue(from.0, dst_layout).load_scalar(fx);
 534                 let dst_ty = fx.clif_type(self.layout().ty).unwrap();
 535                 transmute_value(fx, var, data, dst_ty);
 536                 return;
 537             }
 538             CPlaceInner::VarPair(_local, var1, var2) => {
 539                 let (data1, data2) = CValue(from.0, dst_layout).load_scalar_pair(fx);
 540                 let (dst_ty1, dst_ty2) = fx.clif_pair_type(self.layout().ty).unwrap();
 541                 transmute_value(fx, var1, data1, dst_ty1);
 542                 transmute_value(fx, var2, data2, dst_ty2);
 543                 return;
 544             }
 545             CPlaceInner::VarLane(_local, var, lane) => {
 546                 let data = from.load_scalar(fx);
 547
 548                 // First get the old vector
 549                 let vector = fx.bcx.use_var(var);
 550                 //fx.bcx.set_val_label(vector, cranelift_codegen::ir::ValueLabel::new(var.index()));
 551
 552                 // Next insert the written lane into the vector
 553                 let vector = fx.bcx.ins().insertlane(vector, data, lane);
 554
 555                 // Finally write the new vector
 556                 //fx.bcx.set_val_label(vector, cranelift_codegen::ir::ValueLabel::new(var.index()));
 557                 fx.bcx.def_var(var, vector);
 558
 559                 return;
 560             }
 561             CPlaceInner::Addr(ptr, None) => {
 562                 if dst_layout.size == Size::ZERO || dst_layout.abi == Abi::Uninhabited {
 563                     return;
 564                 }
 565                 ptr
 566             }
 567             CPlaceInner::Addr(_, Some(_)) => bug!("Can't write value to unsized place {:?}", self),
 568         };
 569
 570         let mut flags = MemFlags::new();
 571         flags.set_notrap();
 572         match from.layout().abi {
 573             // FIXME make Abi::Vector work too
 574             Abi::Scalar(_) => {
 575                 let val = from.load_scalar(fx);
 576                 to_ptr.store(fx, val, flags);
 577                 return;
 578             }
 579             Abi::ScalarPair(a_scalar, b_scalar) => {
 580                 let (value, extra) = from.load_scalar_pair(fx);
 581                 let b_offset = scalar_pair_calculate_b_offset(fx.tcx, a_scalar, b_scalar);
 582                 to_ptr.store(fx, value, flags);
 583                 to_ptr.offset(fx, b_offset).store(fx, extra, flags);
 584                 return;
 585             }
 586             _ => {}
 587         }
 588
 589         match from.0 {
 590             CValueInner::ByVal(val) => {
 591                 to_ptr.store(fx, val, flags);
 592             }
 593             CValueInner::ByValPair(_, _) => {
 594                 bug!("Non ScalarPair abi {:?} for ByValPair CValue", dst_layout.abi);
 595             }
 596             CValueInner::ByRef(from_ptr, None) => {
 597                 let from_addr = from_ptr.get_addr(fx);
 598                 let to_addr = to_ptr.get_addr(fx);
 599                 let src_layout = from.1;
 600                 let size = dst_layout.size.bytes();
 601                 let src_align = src_layout.align.abi.bytes() as u8;
 602                 let dst_align = dst_layout.align.abi.bytes() as u8;
 603                 fx.bcx.emit_small_memory_copy(
 604                     fx.target_config,
 605                     to_addr,
 606                     from_addr,
 607                     size,
 608                     dst_align,
 609                     src_align,
 610                     true,
 611                     MemFlags::trusted(),
 612                 );
 613             }
 614             CValueInner::ByRef(_, Some(_)) => todo!(),
 615         }
 616     }
 617
 618     pub(crate) fn place_field(
 619         self,
 620         fx: &mut FunctionCx<'_, '_, 'tcx>,
 621         field: mir::Field,
 622     ) -> CPlace<'tcx> {
 623         let layout = self.layout();
 624
 625         match self.inner {
 626             CPlaceInner::Var(local, var) => match layout.ty.kind() {
 627                 ty::Array(_, _) => {
 628                     // Can only happen for vector types
 629                     return CPlace {
 630                         inner: CPlaceInner::VarLane(local, var, field.as_u32().try_into().unwrap()),
 631                         layout: layout.field(fx, field.as_u32().try_into().unwrap()),
 632                     };
 633                 }
 634                 ty::Adt(adt_def, substs) if layout.ty.is_simd() => {
 635                     let f0_ty = adt_def.non_enum_variant().fields[0].ty(fx.tcx, substs);
 636
 637                     match f0_ty.kind() {
 638                         ty::Array(_, _) => {
 639                             assert_eq!(field.as_u32(), 0);
 640                             return CPlace {
 641                                 inner: CPlaceInner::Var(local, var),
 642                                 layout: layout.field(fx, field.as_u32().try_into().unwrap()),
 643                             };
 644                         }
 645                         _ => {
 646                             return CPlace {
 647                                 inner: CPlaceInner::VarLane(
 648                                     local,
 649                                     var,
 650                                     field.as_u32().try_into().unwrap(),
 651                                 ),
 652                                 layout: layout.field(fx, field.as_u32().try_into().unwrap()),
 653                             };
 654                         }
 655                     }
 656                 }
 657                 _ => {}
 658             },
 659             CPlaceInner::VarPair(local, var1, var2) => {
 660                 let layout = layout.field(&*fx, field.index());
 661
 662                 match field.as_u32() {
 663                     0 => return CPlace { inner: CPlaceInner::Var(local, var1), layout },
 664                     1 => return CPlace { inner: CPlaceInner::Var(local, var2), layout },
 665                     _ => unreachable!("field should be 0 or 1"),
 666                 }
 667             }
 668             _ => {}
 669         }
 670
 671         let (base, extra) = self.to_ptr_maybe_unsized();
 672
 673         let (field_ptr, field_layout) = codegen_field(fx, base, extra, layout, field);
 674         if field_layout.is_unsized() {
 675             if let ty::Foreign(_) = field_layout.ty.kind() {
 676                 assert!(extra.is_none());
 677                 CPlace::for_ptr(field_ptr, field_layout)
 678             } else {
 679                 CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
 680             }
 681         } else {
 682             CPlace::for_ptr(field_ptr, field_layout)
 683         }
 684     }
 685
 686     /// Like [`CPlace::place_field`] except handling ADTs containing a single array field in a way
 687     /// such that you can access individual lanes.
 688     pub(crate) fn place_lane(
 689         self,
 690         fx: &mut FunctionCx<'_, '_, 'tcx>,
 691         lane_idx: u64,
 692     ) -> CPlace<'tcx> {
 693         let layout = self.layout();
 694         assert!(layout.ty.is_simd());
 695         let (lane_count, lane_ty) = layout.ty.simd_size_and_type(fx.tcx);
 696         let lane_layout = fx.layout_of(lane_ty);
 697         assert!(lane_idx < lane_count);
 698
 699         match self.inner {
 700             CPlaceInner::Var(local, var) => {
 701                 assert!(matches!(layout.abi, Abi::Vector { .. }));
 702                 CPlace {
 703                     inner: CPlaceInner::VarLane(local, var, lane_idx.try_into().unwrap()),
 704                     layout: lane_layout,
 705                 }
 706             }
 707             CPlaceInner::VarPair(_, _, _) => unreachable!(),
 708             CPlaceInner::VarLane(_, _, _) => unreachable!(),
 709             CPlaceInner::Addr(ptr, None) => {
 710                 let field_offset = lane_layout.size * lane_idx;
 711                 let field_ptr = ptr.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap());
 712                 CPlace::for_ptr(field_ptr, lane_layout)
 713             }
 714             CPlaceInner::Addr(_, Some(_)) => unreachable!(),
 715         }
 716     }
 717
 718     pub(crate) fn place_index(
 719         self,
 720         fx: &mut FunctionCx<'_, '_, 'tcx>,
 721         index: Value,
 722     ) -> CPlace<'tcx> {
 723         let (elem_layout, ptr) = match self.layout().ty.kind() {
 724             ty::Array(elem_ty, _) => (fx.layout_of(*elem_ty), self.to_ptr()),
 725             ty::Slice(elem_ty) => (fx.layout_of(*elem_ty), self.to_ptr_maybe_unsized().0),
 726             _ => bug!("place_index({:?})", self.layout().ty),
 727         };
 728
 729         let offset = fx.bcx.ins().imul_imm(index, elem_layout.size.bytes() as i64);
 730
 731         CPlace::for_ptr(ptr.offset_value(fx, offset), elem_layout)
 732     }
 733
 734     pub(crate) fn place_deref(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> CPlace<'tcx> {
 735         let inner_layout = fx.layout_of(self.layout().ty.builtin_deref(true).unwrap().ty);
 736         if has_ptr_meta(fx.tcx, inner_layout.ty) {
 737             let (addr, extra) = self.to_cvalue(fx).load_scalar_pair(fx);
 738             CPlace::for_ptr_with_extra(Pointer::new(addr), extra, inner_layout)
 739         } else {
 740             CPlace::for_ptr(Pointer::new(self.to_cvalue(fx).load_scalar(fx)), inner_layout)
 741         }
 742     }
 743
 744     pub(crate) fn place_ref(
 745         self,
 746         fx: &mut FunctionCx<'_, '_, 'tcx>,
 747         layout: TyAndLayout<'tcx>,
 748     ) -> CValue<'tcx> {
 749         if has_ptr_meta(fx.tcx, self.layout().ty) {
 750             let (ptr, extra) = self.to_ptr_maybe_unsized();
 751             CValue::by_val_pair(
 752                 ptr.get_addr(fx),
 753                 extra.expect("unsized type without metadata"),
 754                 layout,
 755             )
 756         } else {
 757             CValue::by_val(self.to_ptr().get_addr(fx), layout)
 758         }
 759     }
 760
 761     pub(crate) fn downcast_variant(
 762         self,
 763         fx: &FunctionCx<'_, '_, 'tcx>,
 764         variant: VariantIdx,
 765     ) -> Self {
 766         assert!(!self.layout().is_unsized());
 767         let layout = self.layout().for_variant(fx, variant);
 768         CPlace { inner: self.inner, layout }
 769     }
 770 }
 771
 772 #[track_caller]
 773 pub(crate) fn assert_assignable<'tcx>(
 774     fx: &FunctionCx<'_, '_, 'tcx>,
 775     from_ty: Ty<'tcx>,
 776     to_ty: Ty<'tcx>,
 777 ) {
 778     match (from_ty.kind(), to_ty.kind()) {
 779         (ty::Ref(_, a, _), ty::Ref(_, b, _))
 780         | (
 781             ty::RawPtr(TypeAndMut { ty: a, mutbl: _ }),
 782             ty::RawPtr(TypeAndMut { ty: b, mutbl: _ }),
 783         ) => {
 784             assert_assignable(fx, *a, *b);
 785         }
 786         (ty::Ref(_, a, _), ty::RawPtr(TypeAndMut { ty: b, mutbl: _ }))
 787         | (ty::RawPtr(TypeAndMut { ty: a, mutbl: _ }), ty::Ref(_, b, _)) => {
 788             assert_assignable(fx, *a, *b);
 789         }
 790         (ty::FnPtr(_), ty::FnPtr(_)) => {
 791             let from_sig = fx.tcx.normalize_erasing_late_bound_regions(
 792                 ParamEnv::reveal_all(),
 793                 from_ty.fn_sig(fx.tcx),
 794             );
 795             let to_sig = fx
 796                 .tcx
 797                 .normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), to_ty.fn_sig(fx.tcx));
 798             assert_eq!(
 799                 from_sig, to_sig,
 800                 "Can't write fn ptr with incompatible sig {:?} to place with sig {:?}\n\n{:#?}",
 801                 from_sig, to_sig, fx,
 802             );
 803             // fn(&T) -> for<'l> fn(&'l T) is allowed
 804         }
 805         (&ty::Dynamic(from_traits, _), &ty::Dynamic(to_traits, _)) => {
 806             for (from, to) in from_traits.iter().zip(to_traits) {
 807                 let from =
 808                     fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), from);
 809                 let to = fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), to);
 810                 assert_eq!(
 811                     from, to,
 812                     "Can't write trait object of incompatible traits {:?} to place with traits {:?}\n\n{:#?}",
 813                     from_traits, to_traits, fx,
 814                 );
 815             }
 816             // dyn for<'r> Trait<'r> -> dyn Trait<'_> is allowed
 817         }
 818         (&ty::Adt(adt_def_a, substs_a), &ty::Adt(adt_def_b, substs_b))
 819             if adt_def_a.did() == adt_def_b.did() =>
 820         {
 821             let mut types_a = substs_a.types();
 822             let mut types_b = substs_b.types();
 823             loop {
 824                 match (types_a.next(), types_b.next()) {
 825                     (Some(a), Some(b)) => assert_assignable(fx, a, b),
 826                     (None, None) => return,
 827                     (Some(_), None) | (None, Some(_)) => panic!("{:#?}/{:#?}", from_ty, to_ty),
 828                 }
 829             }
 830         }
 831         _ => {
 832             assert_eq!(
 833                 from_ty, to_ty,
 834                 "Can't write value with incompatible type {:?} to place with type {:?}\n\n{:#?}",
 835                 from_ty, to_ty, fx,
 836             );
 837         }
 838     }
 839 }