src/librustc_trans/mir/rvalue.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use llvm::{self, ValueRef};
  12 use rustc::ty::{self, Ty};
  13 use rustc::ty::cast::{CastTy, IntTy};
  14 use rustc::ty::layout::Layout;
  15 use rustc::ty::subst::{Kind, Subst};
  16 use rustc::mir::tcx::LvalueTy;
  17 use rustc::mir;
  18 use middle::lang_items::ExchangeMallocFnLangItem;
  19
  20 use base;
  21 use builder::Builder;
  22 use callee::Callee;
  23 use common::{self, val_ty, C_bool, C_null, C_uint};
  24 use common::{C_integral};
  25 use adt;
  26 use machine;
  27 use type_::Type;
  28 use type_of;
  29 use tvec;
  30 use value::Value;
  31 use Disr;
  32
  33 use super::MirContext;
  34 use super::constant::const_scalar_checked_binop;
  35 use super::operand::{OperandRef, OperandValue};
  36 use super::lvalue::LvalueRef;
  37
  38 impl<'a, 'tcx> MirContext<'a, 'tcx> {
  39     pub fn trans_rvalue(&mut self,
  40                         bcx: Builder<'a, 'tcx>,
  41                         dest: LvalueRef<'tcx>,
  42                         rvalue: &mir::Rvalue<'tcx>)
  43                         -> Builder<'a, 'tcx>
  44     {
  45         debug!("trans_rvalue(dest.llval={:?}, rvalue={:?})",
  46                Value(dest.llval), rvalue);
  47
  48         match *rvalue {
  49            mir::Rvalue::Use(ref operand) => {
  50                let tr_operand = self.trans_operand(&bcx, operand);
  51                // FIXME: consider not copying constants through stack. (fixable by translating
  52                // constants into OperandValue::Ref, why don’t we do that yet if we don’t?)
  53                self.store_operand(&bcx, dest.llval, dest.alignment.to_align(), tr_operand);
  54                bcx
  55            }
  56
  57             mir::Rvalue::Cast(mir::CastKind::Unsize, ref source, cast_ty) => {
  58                 let cast_ty = self.monomorphize(&cast_ty);
  59
  60                 if common::type_is_fat_ptr(bcx.ccx, cast_ty) {
  61                     // into-coerce of a thin pointer to a fat pointer - just
  62                     // use the operand path.
  63                     let (bcx, temp) = self.trans_rvalue_operand(bcx, rvalue);
  64                     self.store_operand(&bcx, dest.llval, dest.alignment.to_align(), temp);
  65                     return bcx;
  66                 }
  67
  68                 // Unsize of a nontrivial struct. I would prefer for
  69                 // this to be eliminated by MIR translation, but
  70                 // `CoerceUnsized` can be passed by a where-clause,
  71                 // so the (generic) MIR may not be able to expand it.
  72                 let operand = self.trans_operand(&bcx, source);
  73                 let operand = operand.pack_if_pair(&bcx);
  74                 let llref = match operand.val {
  75                     OperandValue::Pair(..) => bug!(),
  76                     OperandValue::Immediate(llval) => {
  77                         // unsize from an immediate structure. We don't
  78                         // really need a temporary alloca here, but
  79                         // avoiding it would require us to have
  80                         // `coerce_unsized_into` use extractvalue to
  81                         // index into the struct, and this case isn't
  82                         // important enough for it.
  83                         debug!("trans_rvalue: creating ugly alloca");
  84                         let scratch = LvalueRef::alloca(&bcx, operand.ty, "__unsize_temp");
  85                         base::store_ty(&bcx, llval, scratch.llval, scratch.alignment, operand.ty);
  86                         scratch
  87                     }
  88                     OperandValue::Ref(llref, align) => {
  89                         LvalueRef::new_sized_ty(llref, operand.ty, align)
  90                     }
  91                 };
  92                 base::coerce_unsized_into(&bcx, &llref, &dest);
  93                 bcx
  94             }
  95
  96             mir::Rvalue::Repeat(ref elem, ref count) => {
  97                 let tr_elem = self.trans_operand(&bcx, elem);
  98                 let size = count.as_u64(bcx.tcx().sess.target.uint_type);
  99                 let size = C_uint(bcx.ccx, size);
 100                 let base = base::get_dataptr(&bcx, dest.llval);
 101                 tvec::slice_for_each(&bcx, base, tr_elem.ty, size, |bcx, llslot| {
 102                     self.store_operand(bcx, llslot, dest.alignment.to_align(), tr_elem);
 103                 })
 104             }
 105
 106             mir::Rvalue::Aggregate(ref kind, ref operands) => {
 107                 match *kind {
 108                     mir::AggregateKind::Adt(adt_def, variant_index, substs, active_field_index) => {
 109                         let disr = Disr::for_variant(bcx.tcx(), adt_def, variant_index);
 110                         let dest_ty = dest.ty.to_ty(bcx.tcx());
 111                         adt::trans_set_discr(&bcx, dest_ty, dest.llval, disr);
 112                         for (i, operand) in operands.iter().enumerate() {
 113                             let op = self.trans_operand(&bcx, operand);
 114                             // Do not generate stores and GEPis for zero-sized fields.
 115                             if !common::type_is_zero_size(bcx.ccx, op.ty) {
 116                                 let mut val = LvalueRef::new_sized(
 117                                     dest.llval, dest.ty, dest.alignment);
 118                                 let field_index = active_field_index.unwrap_or(i);
 119                                 val.ty = LvalueTy::Downcast {
 120                                     adt_def: adt_def,
 121                                     substs: self.monomorphize(&substs),
 122                                     variant_index: variant_index,
 123                                 };
 124                                 let (lldest_i, align) = val.trans_field_ptr(&bcx, field_index);
 125                                 self.store_operand(&bcx, lldest_i, align.to_align(), op);
 126                             }
 127                         }
 128                     },
 129                     _ => {
 130                         // If this is a tuple or closure, we need to translate GEP indices.
 131                         let layout = bcx.ccx.layout_of(dest.ty.to_ty(bcx.tcx()));
 132                         let translation = if let Layout::Univariant { ref variant, .. } = *layout {
 133                             Some(&variant.memory_index)
 134                         } else {
 135                             None
 136                         };
 137                         let alignment = dest.alignment;
 138                         for (i, operand) in operands.iter().enumerate() {
 139                             let op = self.trans_operand(&bcx, operand);
 140                             // Do not generate stores and GEPis for zero-sized fields.
 141                             if !common::type_is_zero_size(bcx.ccx, op.ty) {
 142                                 // Note: perhaps this should be StructGep, but
 143                                 // note that in some cases the values here will
 144                                 // not be structs but arrays.
 145                                 let i = if let Some(ref t) = translation {
 146                                     t[i] as usize
 147                                 } else {
 148                                     i
 149                                 };
 150                                 let dest = bcx.gepi(dest.llval, &[0, i]);
 151                                 self.store_operand(&bcx, dest, alignment.to_align(), op);
 152                             }
 153                         }
 154                     }
 155                 }
 156                 bcx
 157             }
 158
 159             _ => {
 160                 assert!(rvalue_creates_operand(rvalue));
 161                 let (bcx, temp) = self.trans_rvalue_operand(bcx, rvalue);
 162                 self.store_operand(&bcx, dest.llval, dest.alignment.to_align(), temp);
 163                 bcx
 164             }
 165         }
 166     }
 167
 168     pub fn trans_rvalue_operand(&mut self,
 169                                 bcx: Builder<'a, 'tcx>,
 170                                 rvalue: &mir::Rvalue<'tcx>)
 171                                 -> (Builder<'a, 'tcx>, OperandRef<'tcx>)
 172     {
 173         assert!(rvalue_creates_operand(rvalue), "cannot trans {:?} to operand", rvalue);
 174
 175         match *rvalue {
 176             mir::Rvalue::Cast(ref kind, ref source, cast_ty) => {
 177                 let operand = self.trans_operand(&bcx, source);
 178                 debug!("cast operand is {:?}", operand);
 179                 let cast_ty = self.monomorphize(&cast_ty);
 180
 181                 let val = match *kind {
 182                     mir::CastKind::ReifyFnPointer => {
 183                         match operand.ty.sty {
 184                             ty::TyFnDef(def_id, substs, _) => {
 185                                 OperandValue::Immediate(
 186                                     Callee::def(bcx.ccx, def_id, substs)
 187                                         .reify(bcx.ccx))
 188                             }
 189                             _ => {
 190                                 bug!("{} cannot be reified to a fn ptr", operand.ty)
 191                             }
 192                         }
 193                     }
 194                     mir::CastKind::ClosureFnPointer => {
 195                         match operand.ty.sty {
 196                             ty::TyClosure(def_id, substs) => {
 197                                 // Get the def_id for FnOnce::call_once
 198                                 let fn_once = bcx.tcx().lang_items.fn_once_trait().unwrap();
 199                                 let call_once = bcx.tcx()
 200                                     .global_tcx().associated_items(fn_once)
 201                                     .find(|it| it.kind == ty::AssociatedKind::Method)
 202                                     .unwrap().def_id;
 203                                 // Now create its substs [Closure, Tuple]
 204                                 let input = bcx.tcx().closure_type(def_id)
 205                                     .subst(bcx.tcx(), substs.substs).input(0);
 206                                 let substs = bcx.tcx().mk_substs([operand.ty, input.skip_binder()]
 207                                     .iter().cloned().map(Kind::from));
 208                                 OperandValue::Immediate(
 209                                     Callee::def(bcx.ccx, call_once, substs)
 210                                         .reify(bcx.ccx))
 211                             }
 212                             _ => {
 213                                 bug!("{} cannot be cast to a fn ptr", operand.ty)
 214                             }
 215                         }
 216                     }
 217                     mir::CastKind::UnsafeFnPointer => {
 218                         // this is a no-op at the LLVM level
 219                         operand.val
 220                     }
 221                     mir::CastKind::Unsize => {
 222                         // unsize targets other than to a fat pointer currently
 223                         // can't be operands.
 224                         assert!(common::type_is_fat_ptr(bcx.ccx, cast_ty));
 225
 226                         match operand.val {
 227                             OperandValue::Pair(lldata, llextra) => {
 228                                 // unsize from a fat pointer - this is a
 229                                 // "trait-object-to-supertrait" coercion, for
 230                                 // example,
 231                                 //   &'a fmt::Debug+Send => &'a fmt::Debug,
 232                                 // So we need to pointercast the base to ensure
 233                                 // the types match up.
 234                                 let llcast_ty = type_of::fat_ptr_base_ty(bcx.ccx, cast_ty);
 235                                 let lldata = bcx.pointercast(lldata, llcast_ty);
 236                                 OperandValue::Pair(lldata, llextra)
 237                             }
 238                             OperandValue::Immediate(lldata) => {
 239                                 // "standard" unsize
 240                                 let (lldata, llextra) = base::unsize_thin_ptr(&bcx, lldata,
 241                                     operand.ty, cast_ty);
 242                                 OperandValue::Pair(lldata, llextra)
 243                             }
 244                             OperandValue::Ref(..) => {
 245                                 bug!("by-ref operand {:?} in trans_rvalue_operand",
 246                                      operand);
 247                             }
 248                         }
 249                     }
 250                     mir::CastKind::Misc if common::type_is_fat_ptr(bcx.ccx, operand.ty) => {
 251                         let ll_cast_ty = type_of::immediate_type_of(bcx.ccx, cast_ty);
 252                         let ll_from_ty = type_of::immediate_type_of(bcx.ccx, operand.ty);
 253                         if let OperandValue::Pair(data_ptr, meta_ptr) = operand.val {
 254                             if common::type_is_fat_ptr(bcx.ccx, cast_ty) {
 255                                 let ll_cft = ll_cast_ty.field_types();
 256                                 let ll_fft = ll_from_ty.field_types();
 257                                 let data_cast = bcx.pointercast(data_ptr, ll_cft[0]);
 258                                 assert_eq!(ll_cft[1].kind(), ll_fft[1].kind());
 259                                 OperandValue::Pair(data_cast, meta_ptr)
 260                             } else { // cast to thin-ptr
 261                                 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
 262                                 // pointer-cast of that pointer to desired pointer type.
 263                                 let llval = bcx.pointercast(data_ptr, ll_cast_ty);
 264                                 OperandValue::Immediate(llval)
 265                             }
 266                         } else {
 267                             bug!("Unexpected non-Pair operand")
 268                         }
 269                     }
 270                     mir::CastKind::Misc => {
 271                         debug_assert!(common::type_is_immediate(bcx.ccx, cast_ty));
 272                         let r_t_in = CastTy::from_ty(operand.ty).expect("bad input type for cast");
 273                         let r_t_out = CastTy::from_ty(cast_ty).expect("bad output type for cast");
 274                         let ll_t_in = type_of::immediate_type_of(bcx.ccx, operand.ty);
 275                         let ll_t_out = type_of::immediate_type_of(bcx.ccx, cast_ty);
 276                         let llval = operand.immediate();
 277                         let l = bcx.ccx.layout_of(operand.ty);
 278                         let signed = if let Layout::CEnum { signed, min, max, .. } = *l {
 279                             if max > min {
 280                                 // We want `table[e as usize]` to not
 281                                 // have bound checks, and this is the most
 282                                 // convenient place to put the `assume`.
 283
 284                                 base::call_assume(&bcx, bcx.icmp(
 285                                     llvm::IntULE,
 286                                     llval,
 287                                     C_integral(common::val_ty(llval), max, false)
 288                                 ));
 289                             }
 290
 291                             signed
 292                         } else {
 293                             operand.ty.is_signed()
 294                         };
 295
 296                         let newval = match (r_t_in, r_t_out) {
 297                             (CastTy::Int(_), CastTy::Int(_)) => {
 298                                 bcx.intcast(llval, ll_t_out, signed)
 299                             }
 300                             (CastTy::Float, CastTy::Float) => {
 301                                 let srcsz = ll_t_in.float_width();
 302                                 let dstsz = ll_t_out.float_width();
 303                                 if dstsz > srcsz {
 304                                     bcx.fpext(llval, ll_t_out)
 305                                 } else if srcsz > dstsz {
 306                                     bcx.fptrunc(llval, ll_t_out)
 307                                 } else {
 308                                     llval
 309                                 }
 310                             }
 311                             (CastTy::Ptr(_), CastTy::Ptr(_)) |
 312                             (CastTy::FnPtr, CastTy::Ptr(_)) |
 313                             (CastTy::RPtr(_), CastTy::Ptr(_)) =>
 314                                 bcx.pointercast(llval, ll_t_out),
 315                             (CastTy::Ptr(_), CastTy::Int(_)) |
 316                             (CastTy::FnPtr, CastTy::Int(_)) =>
 317                                 bcx.ptrtoint(llval, ll_t_out),
 318                             (CastTy::Int(_), CastTy::Ptr(_)) =>
 319                                 bcx.inttoptr(llval, ll_t_out),
 320                             (CastTy::Int(_), CastTy::Float) if signed =>
 321                                 bcx.sitofp(llval, ll_t_out),
 322                             (CastTy::Int(_), CastTy::Float) =>
 323                                 bcx.uitofp(llval, ll_t_out),
 324                             (CastTy::Float, CastTy::Int(IntTy::I)) =>
 325                                 bcx.fptosi(llval, ll_t_out),
 326                             (CastTy::Float, CastTy::Int(_)) =>
 327                                 bcx.fptoui(llval, ll_t_out),
 328                             _ => bug!("unsupported cast: {:?} to {:?}", operand.ty, cast_ty)
 329                         };
 330                         OperandValue::Immediate(newval)
 331                     }
 332                 };
 333                 let operand = OperandRef {
 334                     val: val,
 335                     ty: cast_ty
 336                 };
 337                 (bcx, operand)
 338             }
 339
 340             mir::Rvalue::Ref(_, bk, ref lvalue) => {
 341                 let tr_lvalue = self.trans_lvalue(&bcx, lvalue);
 342
 343                 let ty = tr_lvalue.ty.to_ty(bcx.tcx());
 344                 let ref_ty = bcx.tcx().mk_ref(
 345                     bcx.tcx().mk_region(ty::ReErased),
 346                     ty::TypeAndMut { ty: ty, mutbl: bk.to_mutbl_lossy() }
 347                 );
 348
 349                 // Note: lvalues are indirect, so storing the `llval` into the
 350                 // destination effectively creates a reference.
 351                 let operand = if bcx.ccx.shared().type_is_sized(ty) {
 352                     OperandRef {
 353                         val: OperandValue::Immediate(tr_lvalue.llval),
 354                         ty: ref_ty,
 355                     }
 356                 } else {
 357                     OperandRef {
 358                         val: OperandValue::Pair(tr_lvalue.llval,
 359                                                 tr_lvalue.llextra),
 360                         ty: ref_ty,
 361                     }
 362                 };
 363                 (bcx, operand)
 364             }
 365
 366             mir::Rvalue::Len(ref lvalue) => {
 367                 let tr_lvalue = self.trans_lvalue(&bcx, lvalue);
 368                 let operand = OperandRef {
 369                     val: OperandValue::Immediate(tr_lvalue.len(bcx.ccx)),
 370                     ty: bcx.tcx().types.usize,
 371                 };
 372                 (bcx, operand)
 373             }
 374
 375             mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 376                 let lhs = self.trans_operand(&bcx, lhs);
 377                 let rhs = self.trans_operand(&bcx, rhs);
 378                 let llresult = if common::type_is_fat_ptr(bcx.ccx, lhs.ty) {
 379                     match (lhs.val, rhs.val) {
 380                         (OperandValue::Pair(lhs_addr, lhs_extra),
 381                          OperandValue::Pair(rhs_addr, rhs_extra)) => {
 382                             self.trans_fat_ptr_binop(&bcx, op,
 383                                                      lhs_addr, lhs_extra,
 384                                                      rhs_addr, rhs_extra,
 385                                                      lhs.ty)
 386                         }
 387                         _ => bug!()
 388                     }
 389
 390                 } else {
 391                     self.trans_scalar_binop(&bcx, op,
 392                                             lhs.immediate(), rhs.immediate(),
 393                                             lhs.ty)
 394                 };
 395                 let operand = OperandRef {
 396                     val: OperandValue::Immediate(llresult),
 397                     ty: op.ty(bcx.tcx(), lhs.ty, rhs.ty),
 398                 };
 399                 (bcx, operand)
 400             }
 401             mir::Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
 402                 let lhs = self.trans_operand(&bcx, lhs);
 403                 let rhs = self.trans_operand(&bcx, rhs);
 404                 let result = self.trans_scalar_checked_binop(&bcx, op,
 405                                                              lhs.immediate(), rhs.immediate(),
 406                                                              lhs.ty);
 407                 let val_ty = op.ty(bcx.tcx(), lhs.ty, rhs.ty);
 408                 let operand_ty = bcx.tcx().intern_tup(&[val_ty, bcx.tcx().types.bool], false);
 409                 let operand = OperandRef {
 410                     val: result,
 411                     ty: operand_ty
 412                 };
 413
 414                 (bcx, operand)
 415             }
 416
 417             mir::Rvalue::UnaryOp(op, ref operand) => {
 418                 let operand = self.trans_operand(&bcx, operand);
 419                 let lloperand = operand.immediate();
 420                 let is_float = operand.ty.is_fp();
 421                 let llval = match op {
 422                     mir::UnOp::Not => bcx.not(lloperand),
 423                     mir::UnOp::Neg => if is_float {
 424                         bcx.fneg(lloperand)
 425                     } else {
 426                         bcx.neg(lloperand)
 427                     }
 428                 };
 429                 (bcx, OperandRef {
 430                     val: OperandValue::Immediate(llval),
 431                     ty: operand.ty,
 432                 })
 433             }
 434
 435             mir::Rvalue::Discriminant(ref lvalue) => {
 436                 let discr_lvalue = self.trans_lvalue(&bcx, lvalue);
 437                 let enum_ty = discr_lvalue.ty.to_ty(bcx.tcx());
 438                 let discr_ty = rvalue.ty(&*self.mir, bcx.tcx());
 439                 let discr_type = type_of::immediate_type_of(bcx.ccx, discr_ty);
 440                 let discr = adt::trans_get_discr(&bcx, enum_ty, discr_lvalue.llval,
 441                                                   discr_lvalue.alignment, Some(discr_type), true);
 442                 (bcx, OperandRef {
 443                     val: OperandValue::Immediate(discr),
 444                     ty: discr_ty
 445                 })
 446             }
 447
 448             mir::Rvalue::Box(content_ty) => {
 449                 let content_ty: Ty<'tcx> = self.monomorphize(&content_ty);
 450                 let llty = type_of::type_of(bcx.ccx, content_ty);
 451                 let llsize = machine::llsize_of(bcx.ccx, llty);
 452                 let align = type_of::align_of(bcx.ccx, content_ty);
 453                 let llalign = C_uint(bcx.ccx, align);
 454                 let llty_ptr = llty.ptr_to();
 455                 let box_ty = bcx.tcx().mk_box(content_ty);
 456
 457                 // Allocate space:
 458                 let def_id = match bcx.tcx().lang_items.require(ExchangeMallocFnLangItem) {
 459                     Ok(id) => id,
 460                     Err(s) => {
 461                         bcx.sess().fatal(&format!("allocation of `{}` {}", box_ty, s));
 462                     }
 463                 };
 464                 let r = Callee::def(bcx.ccx, def_id, bcx.tcx().intern_substs(&[]))
 465                     .reify(bcx.ccx);
 466                 let val = bcx.pointercast(bcx.call(r, &[llsize, llalign], None), llty_ptr);
 467
 468                 let operand = OperandRef {
 469                     val: OperandValue::Immediate(val),
 470                     ty: box_ty,
 471                 };
 472                 (bcx, operand)
 473             }
 474
 475             mir::Rvalue::Use(ref operand) => {
 476                 let operand = self.trans_operand(&bcx, operand);
 477                 (bcx, operand)
 478             }
 479             mir::Rvalue::Repeat(..) |
 480             mir::Rvalue::Aggregate(..) => {
 481                 bug!("cannot generate operand from rvalue {:?}", rvalue);
 482
 483             }
 484         }
 485     }
 486
 487     pub fn trans_scalar_binop(&mut self,
 488                               bcx: &Builder<'a, 'tcx>,
 489                               op: mir::BinOp,
 490                               lhs: ValueRef,
 491                               rhs: ValueRef,
 492                               input_ty: Ty<'tcx>) -> ValueRef {
 493         let is_float = input_ty.is_fp();
 494         let is_signed = input_ty.is_signed();
 495         let is_nil = input_ty.is_nil();
 496         let is_bool = input_ty.is_bool();
 497         match op {
 498             mir::BinOp::Add => if is_float {
 499                 bcx.fadd(lhs, rhs)
 500             } else {
 501                 bcx.add(lhs, rhs)
 502             },
 503             mir::BinOp::Sub => if is_float {
 504                 bcx.fsub(lhs, rhs)
 505             } else {
 506                 bcx.sub(lhs, rhs)
 507             },
 508             mir::BinOp::Mul => if is_float {
 509                 bcx.fmul(lhs, rhs)
 510             } else {
 511                 bcx.mul(lhs, rhs)
 512             },
 513             mir::BinOp::Div => if is_float {
 514                 bcx.fdiv(lhs, rhs)
 515             } else if is_signed {
 516                 bcx.sdiv(lhs, rhs)
 517             } else {
 518                 bcx.udiv(lhs, rhs)
 519             },
 520             mir::BinOp::Rem => if is_float {
 521                 bcx.frem(lhs, rhs)
 522             } else if is_signed {
 523                 bcx.srem(lhs, rhs)
 524             } else {
 525                 bcx.urem(lhs, rhs)
 526             },
 527             mir::BinOp::BitOr => bcx.or(lhs, rhs),
 528             mir::BinOp::BitAnd => bcx.and(lhs, rhs),
 529             mir::BinOp::BitXor => bcx.xor(lhs, rhs),
 530             mir::BinOp::Shl => common::build_unchecked_lshift(bcx, lhs, rhs),
 531             mir::BinOp::Shr => common::build_unchecked_rshift(bcx, input_ty, lhs, rhs),
 532             mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt |
 533             mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => if is_nil {
 534                 C_bool(bcx.ccx, match op {
 535                     mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt => false,
 536                     mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => true,
 537                     _ => unreachable!()
 538                 })
 539             } else if is_float {
 540                 bcx.fcmp(
 541                     base::bin_op_to_fcmp_predicate(op.to_hir_binop()),
 542                     lhs, rhs
 543                 )
 544             } else {
 545                 let (lhs, rhs) = if is_bool {
 546                     // FIXME(#36856) -- extend the bools into `i8` because
 547                     // LLVM's i1 comparisons are broken.
 548                     (bcx.zext(lhs, Type::i8(bcx.ccx)),
 549                      bcx.zext(rhs, Type::i8(bcx.ccx)))
 550                 } else {
 551                     (lhs, rhs)
 552                 };
 553
 554                 bcx.icmp(
 555                     base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed),
 556                     lhs, rhs
 557                 )
 558             }
 559         }
 560     }
 561
 562     pub fn trans_fat_ptr_binop(&mut self,
 563                                bcx: &Builder<'a, 'tcx>,
 564                                op: mir::BinOp,
 565                                lhs_addr: ValueRef,
 566                                lhs_extra: ValueRef,
 567                                rhs_addr: ValueRef,
 568                                rhs_extra: ValueRef,
 569                                _input_ty: Ty<'tcx>)
 570                                -> ValueRef {
 571         match op {
 572             mir::BinOp::Eq => {
 573                 bcx.and(
 574                     bcx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
 575                     bcx.icmp(llvm::IntEQ, lhs_extra, rhs_extra)
 576                 )
 577             }
 578             mir::BinOp::Ne => {
 579                 bcx.or(
 580                     bcx.icmp(llvm::IntNE, lhs_addr, rhs_addr),
 581                     bcx.icmp(llvm::IntNE, lhs_extra, rhs_extra)
 582                 )
 583             }
 584             mir::BinOp::Le | mir::BinOp::Lt |
 585             mir::BinOp::Ge | mir::BinOp::Gt => {
 586                 // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
 587                 let (op, strict_op) = match op {
 588                     mir::BinOp::Lt => (llvm::IntULT, llvm::IntULT),
 589                     mir::BinOp::Le => (llvm::IntULE, llvm::IntULT),
 590                     mir::BinOp::Gt => (llvm::IntUGT, llvm::IntUGT),
 591                     mir::BinOp::Ge => (llvm::IntUGE, llvm::IntUGT),
 592                     _ => bug!(),
 593                 };
 594
 595                 bcx.or(
 596                     bcx.icmp(strict_op, lhs_addr, rhs_addr),
 597                     bcx.and(
 598                         bcx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
 599                         bcx.icmp(op, lhs_extra, rhs_extra)
 600                     )
 601                 )
 602             }
 603             _ => {
 604                 bug!("unexpected fat ptr binop");
 605             }
 606         }
 607     }
 608
 609     pub fn trans_scalar_checked_binop(&mut self,
 610                                       bcx: &Builder<'a, 'tcx>,
 611                                       op: mir::BinOp,
 612                                       lhs: ValueRef,
 613                                       rhs: ValueRef,
 614                                       input_ty: Ty<'tcx>) -> OperandValue {
 615         // This case can currently arise only from functions marked
 616         // with #[rustc_inherit_overflow_checks] and inlined from
 617         // another crate (mostly core::num generic/#[inline] fns),
 618         // while the current crate doesn't use overflow checks.
 619         if !bcx.ccx.check_overflow() {
 620             let val = self.trans_scalar_binop(bcx, op, lhs, rhs, input_ty);
 621             return OperandValue::Pair(val, C_bool(bcx.ccx, false));
 622         }
 623
 624         // First try performing the operation on constants, which
 625         // will only succeed if both operands are constant.
 626         // This is necessary to determine when an overflow Assert
 627         // will always panic at runtime, and produce a warning.
 628         if let Some((val, of)) = const_scalar_checked_binop(bcx.tcx(), op, lhs, rhs, input_ty) {
 629             return OperandValue::Pair(val, C_bool(bcx.ccx, of));
 630         }
 631
 632         let (val, of) = match op {
 633             // These are checked using intrinsics
 634             mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
 635                 let oop = match op {
 636                     mir::BinOp::Add => OverflowOp::Add,
 637                     mir::BinOp::Sub => OverflowOp::Sub,
 638                     mir::BinOp::Mul => OverflowOp::Mul,
 639                     _ => unreachable!()
 640                 };
 641                 let intrinsic = get_overflow_intrinsic(oop, bcx, input_ty);
 642                 let res = bcx.call(intrinsic, &[lhs, rhs], None);
 643
 644                 (bcx.extract_value(res, 0),
 645                  bcx.extract_value(res, 1))
 646             }
 647             mir::BinOp::Shl | mir::BinOp::Shr => {
 648                 let lhs_llty = val_ty(lhs);
 649                 let rhs_llty = val_ty(rhs);
 650                 let invert_mask = common::shift_mask_val(&bcx, lhs_llty, rhs_llty, true);
 651                 let outer_bits = bcx.and(rhs, invert_mask);
 652
 653                 let of = bcx.icmp(llvm::IntNE, outer_bits, C_null(rhs_llty));
 654                 let val = self.trans_scalar_binop(bcx, op, lhs, rhs, input_ty);
 655
 656                 (val, of)
 657             }
 658             _ => {
 659                 bug!("Operator `{:?}` is not a checkable operator", op)
 660             }
 661         };
 662
 663         OperandValue::Pair(val, of)
 664     }
 665 }
 666
 667 pub fn rvalue_creates_operand(rvalue: &mir::Rvalue) -> bool {
 668     match *rvalue {
 669         mir::Rvalue::Ref(..) |
 670         mir::Rvalue::Len(..) |
 671         mir::Rvalue::Cast(..) | // (*)
 672         mir::Rvalue::BinaryOp(..) |
 673         mir::Rvalue::CheckedBinaryOp(..) |
 674         mir::Rvalue::UnaryOp(..) |
 675         mir::Rvalue::Discriminant(..) |
 676         mir::Rvalue::Box(..) |
 677         mir::Rvalue::Use(..) =>
 678             true,
 679         mir::Rvalue::Repeat(..) |
 680         mir::Rvalue::Aggregate(..) =>
 681             false,
 682     }
 683
 684     // (*) this is only true if the type is suitable
 685 }
 686
 687 #[derive(Copy, Clone)]
 688 enum OverflowOp {
 689     Add, Sub, Mul
 690 }
 691
 692 fn get_overflow_intrinsic(oop: OverflowOp, bcx: &Builder, ty: Ty) -> ValueRef {
 693     use syntax::ast::IntTy::*;
 694     use syntax::ast::UintTy::*;
 695     use rustc::ty::{TyInt, TyUint};
 696
 697     let tcx = bcx.tcx();
 698
 699     let new_sty = match ty.sty {
 700         TyInt(Is) => match &tcx.sess.target.target.target_pointer_width[..] {
 701             "16" => TyInt(I16),
 702             "32" => TyInt(I32),
 703             "64" => TyInt(I64),
 704             _ => panic!("unsupported target word size")
 705         },
 706         TyUint(Us) => match &tcx.sess.target.target.target_pointer_width[..] {
 707             "16" => TyUint(U16),
 708             "32" => TyUint(U32),
 709             "64" => TyUint(U64),
 710             _ => panic!("unsupported target word size")
 711         },
 712         ref t @ TyUint(_) | ref t @ TyInt(_) => t.clone(),
 713         _ => panic!("tried to get overflow intrinsic for op applied to non-int type")
 714     };
 715
 716     let name = match oop {
 717         OverflowOp::Add => match new_sty {
 718             TyInt(I8) => "llvm.sadd.with.overflow.i8",
 719             TyInt(I16) => "llvm.sadd.with.overflow.i16",
 720             TyInt(I32) => "llvm.sadd.with.overflow.i32",
 721             TyInt(I64) => "llvm.sadd.with.overflow.i64",
 722             TyInt(I128) => "llvm.sadd.with.overflow.i128",
 723
 724             TyUint(U8) => "llvm.uadd.with.overflow.i8",
 725             TyUint(U16) => "llvm.uadd.with.overflow.i16",
 726             TyUint(U32) => "llvm.uadd.with.overflow.i32",
 727             TyUint(U64) => "llvm.uadd.with.overflow.i64",
 728             TyUint(U128) => "llvm.uadd.with.overflow.i128",
 729
 730             _ => unreachable!(),
 731         },
 732         OverflowOp::Sub => match new_sty {
 733             TyInt(I8) => "llvm.ssub.with.overflow.i8",
 734             TyInt(I16) => "llvm.ssub.with.overflow.i16",
 735             TyInt(I32) => "llvm.ssub.with.overflow.i32",
 736             TyInt(I64) => "llvm.ssub.with.overflow.i64",
 737             TyInt(I128) => "llvm.ssub.with.overflow.i128",
 738
 739             TyUint(U8) => "llvm.usub.with.overflow.i8",
 740             TyUint(U16) => "llvm.usub.with.overflow.i16",
 741             TyUint(U32) => "llvm.usub.with.overflow.i32",
 742             TyUint(U64) => "llvm.usub.with.overflow.i64",
 743             TyUint(U128) => "llvm.usub.with.overflow.i128",
 744
 745             _ => unreachable!(),
 746         },
 747         OverflowOp::Mul => match new_sty {
 748             TyInt(I8) => "llvm.smul.with.overflow.i8",
 749             TyInt(I16) => "llvm.smul.with.overflow.i16",
 750             TyInt(I32) => "llvm.smul.with.overflow.i32",
 751             TyInt(I64) => "llvm.smul.with.overflow.i64",
 752             TyInt(I128) => "llvm.smul.with.overflow.i128",
 753
 754             TyUint(U8) => "llvm.umul.with.overflow.i8",
 755             TyUint(U16) => "llvm.umul.with.overflow.i16",
 756             TyUint(U32) => "llvm.umul.with.overflow.i32",
 757             TyUint(U64) => "llvm.umul.with.overflow.i64",
 758             TyUint(U128) => "llvm.umul.with.overflow.i128",
 759
 760             _ => unreachable!(),
 761         },
 762     };
 763
 764     bcx.ccx.get_intrinsic(&name)
 765 }