compiler/rustc_codegen_ssa/src/mir/intrinsic.rs

   1 use super::operand::{OperandRef, OperandValue};
   2 use super::place::PlaceRef;
   3 use super::FunctionCx;
   4 use crate::common::{span_invalid_monomorphization_error, IntPredicate};
   5 use crate::glue;
   6 use crate::traits::*;
   7 use crate::MemFlags;
   8
   9 use rustc_middle::ty::{self, Ty, TyCtxt};
  10 use rustc_span::{sym, Span};
  11 use rustc_target::abi::call::{FnAbi, PassMode};
  12
  13 fn copy_intrinsic<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
  14     bx: &mut Bx,
  15     allow_overlap: bool,
  16     volatile: bool,
  17     ty: Ty<'tcx>,
  18     dst: Bx::Value,
  19     src: Bx::Value,
  20     count: Bx::Value,
  21 ) {
  22     let layout = bx.layout_of(ty);
  23     let size = layout.size;
  24     let align = layout.align.abi;
  25     let size = bx.mul(bx.const_usize(size.bytes()), count);
  26     let flags = if volatile { MemFlags::VOLATILE } else { MemFlags::empty() };
  27     if allow_overlap {
  28         bx.memmove(dst, align, src, align, size, flags);
  29     } else {
  30         bx.memcpy(dst, align, src, align, size, flags);
  31     }
  32 }
  33
  34 fn memset_intrinsic<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
  35     bx: &mut Bx,
  36     volatile: bool,
  37     ty: Ty<'tcx>,
  38     dst: Bx::Value,
  39     val: Bx::Value,
  40     count: Bx::Value,
  41 ) {
  42     let layout = bx.layout_of(ty);
  43     let size = layout.size;
  44     let align = layout.align.abi;
  45     let size = bx.mul(bx.const_usize(size.bytes()), count);
  46     let flags = if volatile { MemFlags::VOLATILE } else { MemFlags::empty() };
  47     bx.memset(dst, val, size, align, flags);
  48 }
  49
  50 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
  51     pub fn codegen_intrinsic_call(
  52         bx: &mut Bx,
  53         instance: ty::Instance<'tcx>,
  54         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
  55         args: &[OperandRef<'tcx, Bx::Value>],
  56         llresult: Bx::Value,
  57         span: Span,
  58     ) {
  59         let callee_ty = instance.ty(bx.tcx(), ty::ParamEnv::reveal_all());
  60
  61         let (def_id, substs) = match *callee_ty.kind() {
  62             ty::FnDef(def_id, substs) => (def_id, substs),
  63             _ => bug!("expected fn item type, found {}", callee_ty),
  64         };
  65
  66         let sig = callee_ty.fn_sig(bx.tcx());
  67         let sig = bx.tcx().normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
  68         let arg_tys = sig.inputs();
  69         let ret_ty = sig.output();
  70         let name = bx.tcx().item_name(def_id);
  71         let name_str = name.as_str();
  72
  73         let llret_ty = bx.backend_type(bx.layout_of(ret_ty));
  74         let result = PlaceRef::new_sized(llresult, fn_abi.ret.layout);
  75
  76         let llval = match name {
  77             sym::assume => {
  78                 bx.assume(args[0].immediate());
  79                 return;
  80             }
  81             sym::abort => {
  82                 bx.abort();
  83                 return;
  84             }
  85
  86             sym::va_start => bx.va_start(args[0].immediate()),
  87             sym::va_end => bx.va_end(args[0].immediate()),
  88             sym::size_of_val => {
  89                 let tp_ty = substs.type_at(0);
  90                 if let OperandValue::Pair(_, meta) = args[0].val {
  91                     let (llsize, _) = glue::size_and_align_of_dst(bx, tp_ty, Some(meta));
  92                     llsize
  93                 } else {
  94                     bx.const_usize(bx.layout_of(tp_ty).size.bytes())
  95                 }
  96             }
  97             sym::min_align_of_val => {
  98                 let tp_ty = substs.type_at(0);
  99                 if let OperandValue::Pair(_, meta) = args[0].val {
 100                     let (_, llalign) = glue::size_and_align_of_dst(bx, tp_ty, Some(meta));
 101                     llalign
 102                 } else {
 103                     bx.const_usize(bx.layout_of(tp_ty).align.abi.bytes())
 104                 }
 105             }
 106             sym::pref_align_of
 107             | sym::needs_drop
 108             | sym::type_id
 109             | sym::type_name
 110             | sym::variant_count => {
 111                 let value = bx
 112                     .tcx()
 113                     .const_eval_instance(ty::ParamEnv::reveal_all(), instance, None)
 114                     .unwrap();
 115                 OperandRef::from_const(bx, value, ret_ty).immediate_or_packed_pair(bx)
 116             }
 117             sym::offset => {
 118                 let ty = substs.type_at(0);
 119                 let layout = bx.layout_of(ty);
 120                 let ptr = args[0].immediate();
 121                 let offset = args[1].immediate();
 122                 bx.inbounds_gep(bx.backend_type(layout), ptr, &[offset])
 123             }
 124             sym::arith_offset => {
 125                 let ty = substs.type_at(0);
 126                 let layout = bx.layout_of(ty);
 127                 let ptr = args[0].immediate();
 128                 let offset = args[1].immediate();
 129                 bx.gep(bx.backend_type(layout), ptr, &[offset])
 130             }
 131             sym::copy => {
 132                 copy_intrinsic(
 133                     bx,
 134                     true,
 135                     false,
 136                     substs.type_at(0),
 137                     args[1].immediate(),
 138                     args[0].immediate(),
 139                     args[2].immediate(),
 140                 );
 141                 return;
 142             }
 143             sym::write_bytes => {
 144                 memset_intrinsic(
 145                     bx,
 146                     false,
 147                     substs.type_at(0),
 148                     args[0].immediate(),
 149                     args[1].immediate(),
 150                     args[2].immediate(),
 151                 );
 152                 return;
 153             }
 154
 155             sym::volatile_copy_nonoverlapping_memory => {
 156                 copy_intrinsic(
 157                     bx,
 158                     false,
 159                     true,
 160                     substs.type_at(0),
 161                     args[0].immediate(),
 162                     args[1].immediate(),
 163                     args[2].immediate(),
 164                 );
 165                 return;
 166             }
 167             sym::volatile_copy_memory => {
 168                 copy_intrinsic(
 169                     bx,
 170                     true,
 171                     true,
 172                     substs.type_at(0),
 173                     args[0].immediate(),
 174                     args[1].immediate(),
 175                     args[2].immediate(),
 176                 );
 177                 return;
 178             }
 179             sym::volatile_set_memory => {
 180                 memset_intrinsic(
 181                     bx,
 182                     true,
 183                     substs.type_at(0),
 184                     args[0].immediate(),
 185                     args[1].immediate(),
 186                     args[2].immediate(),
 187                 );
 188                 return;
 189             }
 190             sym::volatile_store => {
 191                 let dst = args[0].deref(bx.cx());
 192                 args[1].val.volatile_store(bx, dst);
 193                 return;
 194             }
 195             sym::unaligned_volatile_store => {
 196                 let dst = args[0].deref(bx.cx());
 197                 args[1].val.unaligned_volatile_store(bx, dst);
 198                 return;
 199             }
 200             sym::add_with_overflow
 201             | sym::sub_with_overflow
 202             | sym::mul_with_overflow
 203             | sym::unchecked_div
 204             | sym::unchecked_rem
 205             | sym::unchecked_shl
 206             | sym::unchecked_shr
 207             | sym::unchecked_add
 208             | sym::unchecked_sub
 209             | sym::unchecked_mul
 210             | sym::exact_div => {
 211                 let ty = arg_tys[0];
 212                 match int_type_width_signed(ty, bx.tcx()) {
 213                     Some((_width, signed)) => match name {
 214                         sym::add_with_overflow
 215                         | sym::sub_with_overflow
 216                         | sym::mul_with_overflow => {
 217                             let op = match name {
 218                                 sym::add_with_overflow => OverflowOp::Add,
 219                                 sym::sub_with_overflow => OverflowOp::Sub,
 220                                 sym::mul_with_overflow => OverflowOp::Mul,
 221                                 _ => bug!(),
 222                             };
 223                             let (val, overflow) =
 224                                 bx.checked_binop(op, ty, args[0].immediate(), args[1].immediate());
 225                             // Convert `i1` to a `bool`, and write it to the out parameter
 226                             let val = bx.from_immediate(val);
 227                             let overflow = bx.from_immediate(overflow);
 228
 229                             let dest = result.project_field(bx, 0);
 230                             bx.store(val, dest.llval, dest.align);
 231                             let dest = result.project_field(bx, 1);
 232                             bx.store(overflow, dest.llval, dest.align);
 233
 234                             return;
 235                         }
 236                         sym::exact_div => {
 237                             if signed {
 238                                 bx.exactsdiv(args[0].immediate(), args[1].immediate())
 239                             } else {
 240                                 bx.exactudiv(args[0].immediate(), args[1].immediate())
 241                             }
 242                         }
 243                         sym::unchecked_div => {
 244                             if signed {
 245                                 bx.sdiv(args[0].immediate(), args[1].immediate())
 246                             } else {
 247                                 bx.udiv(args[0].immediate(), args[1].immediate())
 248                             }
 249                         }
 250                         sym::unchecked_rem => {
 251                             if signed {
 252                                 bx.srem(args[0].immediate(), args[1].immediate())
 253                             } else {
 254                                 bx.urem(args[0].immediate(), args[1].immediate())
 255                             }
 256                         }
 257                         sym::unchecked_shl => bx.shl(args[0].immediate(), args[1].immediate()),
 258                         sym::unchecked_shr => {
 259                             if signed {
 260                                 bx.ashr(args[0].immediate(), args[1].immediate())
 261                             } else {
 262                                 bx.lshr(args[0].immediate(), args[1].immediate())
 263                             }
 264                         }
 265                         sym::unchecked_add => {
 266                             if signed {
 267                                 bx.unchecked_sadd(args[0].immediate(), args[1].immediate())
 268                             } else {
 269                                 bx.unchecked_uadd(args[0].immediate(), args[1].immediate())
 270                             }
 271                         }
 272                         sym::unchecked_sub => {
 273                             if signed {
 274                                 bx.unchecked_ssub(args[0].immediate(), args[1].immediate())
 275                             } else {
 276                                 bx.unchecked_usub(args[0].immediate(), args[1].immediate())
 277                             }
 278                         }
 279                         sym::unchecked_mul => {
 280                             if signed {
 281                                 bx.unchecked_smul(args[0].immediate(), args[1].immediate())
 282                             } else {
 283                                 bx.unchecked_umul(args[0].immediate(), args[1].immediate())
 284                             }
 285                         }
 286                         _ => bug!(),
 287                     },
 288                     None => {
 289                         span_invalid_monomorphization_error(
 290                             bx.tcx().sess,
 291                             span,
 292                             &format!(
 293                                 "invalid monomorphization of `{}` intrinsic: \
 294                                       expected basic integer type, found `{}`",
 295                                 name, ty
 296                             ),
 297                         );
 298                         return;
 299                     }
 300                 }
 301             }
 302             sym::fadd_fast | sym::fsub_fast | sym::fmul_fast | sym::fdiv_fast | sym::frem_fast => {
 303                 match float_type_width(arg_tys[0]) {
 304                     Some(_width) => match name {
 305                         sym::fadd_fast => bx.fadd_fast(args[0].immediate(), args[1].immediate()),
 306                         sym::fsub_fast => bx.fsub_fast(args[0].immediate(), args[1].immediate()),
 307                         sym::fmul_fast => bx.fmul_fast(args[0].immediate(), args[1].immediate()),
 308                         sym::fdiv_fast => bx.fdiv_fast(args[0].immediate(), args[1].immediate()),
 309                         sym::frem_fast => bx.frem_fast(args[0].immediate(), args[1].immediate()),
 310                         _ => bug!(),
 311                     },
 312                     None => {
 313                         span_invalid_monomorphization_error(
 314                             bx.tcx().sess,
 315                             span,
 316                             &format!(
 317                                 "invalid monomorphization of `{}` intrinsic: \
 318                                       expected basic float type, found `{}`",
 319                                 name, arg_tys[0]
 320                             ),
 321                         );
 322                         return;
 323                     }
 324                 }
 325             }
 326
 327             sym::float_to_int_unchecked => {
 328                 if float_type_width(arg_tys[0]).is_none() {
 329                     span_invalid_monomorphization_error(
 330                         bx.tcx().sess,
 331                         span,
 332                         &format!(
 333                             "invalid monomorphization of `float_to_int_unchecked` \
 334                                   intrinsic: expected basic float type, \
 335                                   found `{}`",
 336                             arg_tys[0]
 337                         ),
 338                     );
 339                     return;
 340                 }
 341                 let (_width, signed) = match int_type_width_signed(ret_ty, bx.tcx()) {
 342                     Some(pair) => pair,
 343                     None => {
 344                         span_invalid_monomorphization_error(
 345                             bx.tcx().sess,
 346                             span,
 347                             &format!(
 348                                 "invalid monomorphization of `float_to_int_unchecked` \
 349                                       intrinsic:  expected basic integer type, \
 350                                       found `{}`",
 351                                 ret_ty
 352                             ),
 353                         );
 354                         return;
 355                     }
 356                 };
 357                 if signed {
 358                     bx.fptosi(args[0].immediate(), llret_ty)
 359                 } else {
 360                     bx.fptoui(args[0].immediate(), llret_ty)
 361                 }
 362             }
 363
 364             sym::discriminant_value => {
 365                 if ret_ty.is_integral() {
 366                     args[0].deref(bx.cx()).codegen_get_discr(bx, ret_ty)
 367                 } else {
 368                     span_bug!(span, "Invalid discriminant type for `{:?}`", arg_tys[0])
 369                 }
 370             }
 371
 372             sym::const_allocate => {
 373                 // returns a null pointer at runtime.
 374                 bx.const_null(bx.type_i8p())
 375             }
 376
 377             sym::const_deallocate => {
 378                 // nop at runtime.
 379                 return;
 380             }
 381
 382             // This requires that atomic intrinsics follow a specific naming pattern:
 383             // "atomic_<operation>[_<ordering>]", and no ordering means SeqCst
 384             name if name_str.starts_with("atomic_") => {
 385                 use crate::common::AtomicOrdering::*;
 386                 use crate::common::{AtomicRmwBinOp, SynchronizationScope};
 387
 388                 let split: Vec<_> = name_str.split('_').collect();
 389
 390                 let is_cxchg = split[1] == "cxchg" || split[1] == "cxchgweak";
 391                 let (order, failorder) = match split.len() {
 392                     2 => (SequentiallyConsistent, SequentiallyConsistent),
 393                     3 => match split[2] {
 394                         "unordered" => (Unordered, Unordered),
 395                         "relaxed" => (Monotonic, Monotonic),
 396                         "acq" => (Acquire, Acquire),
 397                         "rel" => (Release, Monotonic),
 398                         "acqrel" => (AcquireRelease, Acquire),
 399                         "failrelaxed" if is_cxchg => (SequentiallyConsistent, Monotonic),
 400                         "failacq" if is_cxchg => (SequentiallyConsistent, Acquire),
 401                         _ => bx.sess().fatal("unknown ordering in atomic intrinsic"),
 402                     },
 403                     4 => match (split[2], split[3]) {
 404                         ("acq", "failrelaxed") if is_cxchg => (Acquire, Monotonic),
 405                         ("acqrel", "failrelaxed") if is_cxchg => (AcquireRelease, Monotonic),
 406                         _ => bx.sess().fatal("unknown ordering in atomic intrinsic"),
 407                     },
 408                     _ => bx.sess().fatal("Atomic intrinsic not in correct format"),
 409                 };
 410
 411                 let invalid_monomorphization = |ty| {
 412                     span_invalid_monomorphization_error(
 413                         bx.tcx().sess,
 414                         span,
 415                         &format!(
 416                             "invalid monomorphization of `{}` intrinsic: \
 417                                   expected basic integer type, found `{}`",
 418                             name, ty
 419                         ),
 420                     );
 421                 };
 422
 423                 match split[1] {
 424                     "cxchg" | "cxchgweak" => {
 425                         let ty = substs.type_at(0);
 426                         if int_type_width_signed(ty, bx.tcx()).is_some() || ty.is_unsafe_ptr() {
 427                             let weak = split[1] == "cxchgweak";
 428                             let mut dst = args[0].immediate();
 429                             let mut cmp = args[1].immediate();
 430                             let mut src = args[2].immediate();
 431                             if ty.is_unsafe_ptr() {
 432                                 // Some platforms do not support atomic operations on pointers,
 433                                 // so we cast to integer first.
 434                                 let ptr_llty = bx.type_ptr_to(bx.type_isize());
 435                                 dst = bx.pointercast(dst, ptr_llty);
 436                                 cmp = bx.ptrtoint(cmp, bx.type_isize());
 437                                 src = bx.ptrtoint(src, bx.type_isize());
 438                             }
 439                             let pair = bx.atomic_cmpxchg(dst, cmp, src, order, failorder, weak);
 440                             let val = bx.extract_value(pair, 0);
 441                             let success = bx.extract_value(pair, 1);
 442                             let val = bx.from_immediate(val);
 443                             let success = bx.from_immediate(success);
 444
 445                             let dest = result.project_field(bx, 0);
 446                             bx.store(val, dest.llval, dest.align);
 447                             let dest = result.project_field(bx, 1);
 448                             bx.store(success, dest.llval, dest.align);
 449                             return;
 450                         } else {
 451                             return invalid_monomorphization(ty);
 452                         }
 453                     }
 454
 455                     "load" => {
 456                         let ty = substs.type_at(0);
 457                         if int_type_width_signed(ty, bx.tcx()).is_some() || ty.is_unsafe_ptr() {
 458                             let layout = bx.layout_of(ty);
 459                             let size = layout.size;
 460                             let mut source = args[0].immediate();
 461                             if ty.is_unsafe_ptr() {
 462                                 // Some platforms do not support atomic operations on pointers,
 463                                 // so we cast to integer first...
 464                                 let llty = bx.type_isize();
 465                                 let ptr_llty = bx.type_ptr_to(llty);
 466                                 source = bx.pointercast(source, ptr_llty);
 467                                 let result = bx.atomic_load(llty, source, order, size);
 468                                 // ... and then cast the result back to a pointer
 469                                 bx.inttoptr(result, bx.backend_type(layout))
 470                             } else {
 471                                 bx.atomic_load(bx.backend_type(layout), source, order, size)
 472                             }
 473                         } else {
 474                             return invalid_monomorphization(ty);
 475                         }
 476                     }
 477
 478                     "store" => {
 479                         let ty = substs.type_at(0);
 480                         if int_type_width_signed(ty, bx.tcx()).is_some() || ty.is_unsafe_ptr() {
 481                             let size = bx.layout_of(ty).size;
 482                             let mut val = args[1].immediate();
 483                             let mut ptr = args[0].immediate();
 484                             if ty.is_unsafe_ptr() {
 485                                 // Some platforms do not support atomic operations on pointers,
 486                                 // so we cast to integer first.
 487                                 let ptr_llty = bx.type_ptr_to(bx.type_isize());
 488                                 ptr = bx.pointercast(ptr, ptr_llty);
 489                                 val = bx.ptrtoint(val, bx.type_isize());
 490                             }
 491                             bx.atomic_store(val, ptr, order, size);
 492                             return;
 493                         } else {
 494                             return invalid_monomorphization(ty);
 495                         }
 496                     }
 497
 498                     "fence" => {
 499                         bx.atomic_fence(order, SynchronizationScope::CrossThread);
 500                         return;
 501                     }
 502
 503                     "singlethreadfence" => {
 504                         bx.atomic_fence(order, SynchronizationScope::SingleThread);
 505                         return;
 506                     }
 507
 508                     // These are all AtomicRMW ops
 509                     op => {
 510                         let atom_op = match op {
 511                             "xchg" => AtomicRmwBinOp::AtomicXchg,
 512                             "xadd" => AtomicRmwBinOp::AtomicAdd,
 513                             "xsub" => AtomicRmwBinOp::AtomicSub,
 514                             "and" => AtomicRmwBinOp::AtomicAnd,
 515                             "nand" => AtomicRmwBinOp::AtomicNand,
 516                             "or" => AtomicRmwBinOp::AtomicOr,
 517                             "xor" => AtomicRmwBinOp::AtomicXor,
 518                             "max" => AtomicRmwBinOp::AtomicMax,
 519                             "min" => AtomicRmwBinOp::AtomicMin,
 520                             "umax" => AtomicRmwBinOp::AtomicUMax,
 521                             "umin" => AtomicRmwBinOp::AtomicUMin,
 522                             _ => bx.sess().fatal("unknown atomic operation"),
 523                         };
 524
 525                         let ty = substs.type_at(0);
 526                         if int_type_width_signed(ty, bx.tcx()).is_some()
 527                             || (ty.is_unsafe_ptr() && op == "xchg")
 528                         {
 529                             let mut ptr = args[0].immediate();
 530                             let mut val = args[1].immediate();
 531                             if ty.is_unsafe_ptr() {
 532                                 // Some platforms do not support atomic operations on pointers,
 533                                 // so we cast to integer first.
 534                                 let ptr_llty = bx.type_ptr_to(bx.type_isize());
 535                                 ptr = bx.pointercast(ptr, ptr_llty);
 536                                 val = bx.ptrtoint(val, bx.type_isize());
 537                             }
 538                             bx.atomic_rmw(atom_op, ptr, val, order)
 539                         } else {
 540                             return invalid_monomorphization(ty);
 541                         }
 542                     }
 543                 }
 544             }
 545
 546             sym::nontemporal_store => {
 547                 let dst = args[0].deref(bx.cx());
 548                 args[1].val.nontemporal_store(bx, dst);
 549                 return;
 550             }
 551
 552             sym::ptr_guaranteed_eq | sym::ptr_guaranteed_ne => {
 553                 let a = args[0].immediate();
 554                 let b = args[1].immediate();
 555                 if name == sym::ptr_guaranteed_eq {
 556                     bx.icmp(IntPredicate::IntEQ, a, b)
 557                 } else {
 558                     bx.icmp(IntPredicate::IntNE, a, b)
 559                 }
 560             }
 561
 562             sym::ptr_offset_from => {
 563                 let ty = substs.type_at(0);
 564                 let pointee_size = bx.layout_of(ty).size;
 565
 566                 // This is the same sequence that Clang emits for pointer subtraction.
 567                 // It can be neither `nsw` nor `nuw` because the input is treated as
 568                 // unsigned but then the output is treated as signed, so neither works.
 569                 let a = args[0].immediate();
 570                 let b = args[1].immediate();
 571                 let a = bx.ptrtoint(a, bx.type_isize());
 572                 let b = bx.ptrtoint(b, bx.type_isize());
 573                 let d = bx.sub(a, b);
 574                 let pointee_size = bx.const_usize(pointee_size.bytes());
 575                 // this is where the signed magic happens (notice the `s` in `exactsdiv`)
 576                 bx.exactsdiv(d, pointee_size)
 577             }
 578
 579             _ => {
 580                 // Need to use backend-specific things in the implementation.
 581                 bx.codegen_intrinsic_call(instance, fn_abi, args, llresult, span);
 582                 return;
 583             }
 584         };
 585
 586         if !fn_abi.ret.is_ignore() {
 587             if let PassMode::Cast(ty) = fn_abi.ret.mode {
 588                 let ptr_llty = bx.type_ptr_to(bx.cast_backend_type(&ty));
 589                 let ptr = bx.pointercast(result.llval, ptr_llty);
 590                 bx.store(llval, ptr, result.align);
 591             } else {
 592                 OperandRef::from_immediate_or_packed_pair(bx, llval, result.layout)
 593                     .val
 594                     .store(bx, result);
 595             }
 596         }
 597     }
 598 }
 599
 600 // Returns the width of an int Ty, and if it's signed or not
 601 // Returns None if the type is not an integer
 602 // FIXME: there’s multiple of this functions, investigate using some of the already existing
 603 // stuffs.
 604 fn int_type_width_signed(ty: Ty<'_>, tcx: TyCtxt<'_>) -> Option<(u64, bool)> {
 605     match ty.kind() {
 606         ty::Int(t) => {
 607             Some((t.bit_width().unwrap_or(u64::from(tcx.sess.target.pointer_width)), true))
 608         }
 609         ty::Uint(t) => {
 610             Some((t.bit_width().unwrap_or(u64::from(tcx.sess.target.pointer_width)), false))
 611         }
 612         _ => None,
 613     }
 614 }
 615
 616 // Returns the width of a float Ty
 617 // Returns None if the type is not a float
 618 fn float_type_width(ty: Ty<'_>) -> Option<u64> {
 619     match ty.kind() {
 620         ty::Float(t) => Some(t.bit_width()),
 621         _ => None,
 622     }
 623 }