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