src/librustc_trans/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::ValueRef;
  12 use rustc::middle::ty::{self, Ty};
  13 use middle::ty::cast::{CastTy, IntTy};
  14 use middle::const_eval::ConstVal;
  15 use rustc_const_eval::ConstInt;
  16 use rustc::mir::repr as mir;
  17
  18 use trans::asm;
  19 use trans::base;
  20 use trans::callee::Callee;
  21 use trans::common::{self, BlockAndBuilder, Result};
  22 use trans::debuginfo::DebugLoc;
  23 use trans::declare;
  24 use trans::expr;
  25 use trans::adt;
  26 use trans::machine;
  27 use trans::type_::Type;
  28 use trans::type_of;
  29 use trans::tvec;
  30 use trans::Disr;
  31
  32 use super::MirContext;
  33 use super::operand::{OperandRef, OperandValue};
  34 use super::lvalue::LvalueRef;
  35
  36 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  37     pub fn trans_rvalue(&mut self,
  38                         bcx: BlockAndBuilder<'bcx, 'tcx>,
  39                         dest: LvalueRef<'tcx>,
  40                         rvalue: &mir::Rvalue<'tcx>)
  41                         -> BlockAndBuilder<'bcx, 'tcx>
  42     {
  43         debug!("trans_rvalue(dest.llval={}, rvalue={:?})",
  44                bcx.val_to_string(dest.llval),
  45                rvalue);
  46
  47         match *rvalue {
  48            mir::Rvalue::Use(ref operand) => {
  49                let tr_operand = self.trans_operand(&bcx, operand);
  50                // FIXME: consider not copying constants through stack. (fixable by translating
  51                // constants into OperandValue::Ref, why don’t we do that yet if we don’t?)
  52                self.store_operand(&bcx, dest.llval, tr_operand);
  53                self.set_operand_dropped(&bcx, operand);
  54                bcx
  55            }
  56
  57             mir::Rvalue::Cast(mir::CastKind::Unsize, ref operand, cast_ty) => {
  58                 if common::type_is_fat_ptr(bcx.tcx(), cast_ty) {
  59                     // into-coerce of a thin pointer to a fat pointer - just
  60                     // use the operand path.
  61                     let (bcx, temp) = self.trans_rvalue_operand(bcx, rvalue);
  62                     self.store_operand(&bcx, dest.llval, temp);
  63                     return bcx;
  64                 }
  65
  66                 // Unsize of a nontrivial struct. I would prefer for
  67                 // this to be eliminated by MIR translation, but
  68                 // `CoerceUnsized` can be passed by a where-clause,
  69                 // so the (generic) MIR may not be able to expand it.
  70                 let operand = self.trans_operand(&bcx, operand);
  71                 bcx.with_block(|bcx| {
  72                     match operand.val {
  73                         OperandValue::FatPtr(..) => unreachable!(),
  74                         OperandValue::Immediate(llval) => {
  75                             // unsize from an immediate structure. We don't
  76                             // really need a temporary alloca here, but
  77                             // avoiding it would require us to have
  78                             // `coerce_unsized_into` use extractvalue to
  79                             // index into the struct, and this case isn't
  80                             // important enough for it.
  81                             debug!("trans_rvalue: creating ugly alloca");
  82                             let lltemp = base::alloc_ty(bcx, operand.ty, "__unsize_temp");
  83                             base::store_ty(bcx, llval, lltemp, operand.ty);
  84                             base::coerce_unsized_into(bcx,
  85                                                       lltemp, operand.ty,
  86                                                       dest.llval, cast_ty);
  87                         }
  88                         OperandValue::Ref(llref) => {
  89                             base::coerce_unsized_into(bcx,
  90                                                       llref, operand.ty,
  91                                                       dest.llval, cast_ty);
  92                         }
  93                     }
  94                 });
  95                 bcx
  96             }
  97
  98             mir::Rvalue::Repeat(ref elem, ref count) => {
  99                 let tr_elem = self.trans_operand(&bcx, elem);
 100                 let count = ConstVal::Integral(ConstInt::Usize(count.value));
 101                 let size = self.trans_constval(&bcx, &count, bcx.tcx().types.usize).immediate();
 102                 let bcx = bcx.map_block(|block| {
 103                     let base = expr::get_dataptr(block, dest.llval);
 104                     tvec::iter_vec_raw(block, base, tr_elem.ty, size, |block, llslot, _| {
 105                         self.store_operand_direct(block, llslot, tr_elem);
 106                         block
 107                     })
 108                 });
 109                 self.set_operand_dropped(&bcx, elem);
 110                 bcx
 111             }
 112
 113             mir::Rvalue::Aggregate(ref kind, ref operands) => {
 114                 match *kind {
 115                     mir::AggregateKind::Adt(adt_def, index, _) => {
 116                         let repr = adt::represent_type(bcx.ccx(), dest.ty.to_ty(bcx.tcx()));
 117                         let disr = Disr::from(adt_def.variants[index].disr_val);
 118                         bcx.with_block(|bcx| {
 119                             adt::trans_set_discr(bcx, &repr, dest.llval, Disr::from(disr));
 120                         });
 121                         for (i, operand) in operands.iter().enumerate() {
 122                             let op = self.trans_operand(&bcx, operand);
 123                             // Do not generate stores and GEPis for zero-sized fields.
 124                             if !common::type_is_zero_size(bcx.ccx(), op.ty) {
 125                                 let val = adt::MaybeSizedValue::sized(dest.llval);
 126                                 let lldest_i = bcx.with_block(|bcx| {
 127                                     adt::trans_field_ptr(bcx, &repr, val, disr, i)
 128                                 });
 129                                 self.store_operand(&bcx, lldest_i, op);
 130                                 self.set_operand_dropped(&bcx, operand);
 131                             }
 132                         }
 133                     },
 134                     _ => {
 135                         for (i, operand) in operands.iter().enumerate() {
 136                             let op = self.trans_operand(&bcx, operand);
 137                             // Do not generate stores and GEPis for zero-sized fields.
 138                             if !common::type_is_zero_size(bcx.ccx(), op.ty) {
 139                                 // Note: perhaps this should be StructGep, but
 140                                 // note that in some cases the values here will
 141                                 // not be structs but arrays.
 142                                 let dest = bcx.gepi(dest.llval, &[0, i]);
 143                                 self.store_operand(&bcx, dest, op);
 144                                 self.set_operand_dropped(&bcx, operand);
 145                             }
 146                         }
 147                     }
 148                 }
 149                 bcx
 150             }
 151
 152             mir::Rvalue::Slice { ref input, from_start, from_end } => {
 153                 let ccx = bcx.ccx();
 154                 let input = self.trans_lvalue(&bcx, input);
 155                 let (llbase, lllen) = bcx.with_block(|bcx| {
 156                     tvec::get_base_and_len(bcx,
 157                                            input.llval,
 158                                            input.ty.to_ty(bcx.tcx()))
 159                 });
 160                 let llbase1 = bcx.gepi(llbase, &[from_start]);
 161                 let adj = common::C_uint(ccx, from_start + from_end);
 162                 let lllen1 = bcx.sub(lllen, adj);
 163                 let (lladdrdest, llmetadest) = bcx.with_block(|bcx| {
 164                     (expr::get_dataptr(bcx, dest.llval), expr::get_meta(bcx, dest.llval))
 165                 });
 166                 bcx.store(llbase1, lladdrdest);
 167                 bcx.store(lllen1, llmetadest);
 168                 bcx
 169             }
 170
 171             mir::Rvalue::InlineAsm(ref inline_asm) => {
 172                 bcx.map_block(|bcx| {
 173                     asm::trans_inline_asm(bcx, inline_asm)
 174                 })
 175             }
 176
 177             _ => {
 178                 assert!(rvalue_creates_operand(rvalue));
 179                 let (bcx, temp) = self.trans_rvalue_operand(bcx, rvalue);
 180                 self.store_operand(&bcx, dest.llval, temp);
 181                 bcx
 182             }
 183         }
 184     }
 185
 186     pub fn trans_rvalue_operand(&mut self,
 187                                 bcx: BlockAndBuilder<'bcx, 'tcx>,
 188                                 rvalue: &mir::Rvalue<'tcx>)
 189                                 -> (BlockAndBuilder<'bcx, 'tcx>, OperandRef<'tcx>)
 190     {
 191         assert!(rvalue_creates_operand(rvalue), "cannot trans {:?} to operand", rvalue);
 192
 193         match *rvalue {
 194             mir::Rvalue::Cast(ref kind, ref operand, cast_ty) => {
 195                 let operand = self.trans_operand(&bcx, operand);
 196                 debug!("cast operand is {}", operand.repr(&bcx));
 197                 let cast_ty = bcx.monomorphize(&cast_ty);
 198
 199                 let val = match *kind {
 200                     mir::CastKind::ReifyFnPointer => {
 201                         match operand.ty.sty {
 202                             ty::TyFnDef(def_id, substs, _) => {
 203                                 OperandValue::Immediate(
 204                                     Callee::def(bcx.ccx(), def_id, substs, operand.ty)
 205                                         .reify(bcx.ccx()).val)
 206                             }
 207                             _ => {
 208                                 unreachable!("{} cannot be reified to a fn ptr", operand.ty)
 209                             }
 210                         }
 211                     }
 212                     mir::CastKind::UnsafeFnPointer => {
 213                         // this is a no-op at the LLVM level
 214                         operand.val
 215                     }
 216                     mir::CastKind::Unsize => {
 217                         // unsize targets other than to a fat pointer currently
 218                         // can't be operands.
 219                         assert!(common::type_is_fat_ptr(bcx.tcx(), cast_ty));
 220
 221                         match operand.val {
 222                             OperandValue::FatPtr(..) => {
 223                                 // unsize from a fat pointer - this is a
 224                                 // "trait-object-to-supertrait" coercion, for
 225                                 // example,
 226                                 //   &'a fmt::Debug+Send => &'a fmt::Debug,
 227                                 // and is a no-op at the LLVM level
 228                                 operand.val
 229                             }
 230                             OperandValue::Immediate(lldata) => {
 231                                 // "standard" unsize
 232                                 let (lldata, llextra) = bcx.with_block(|bcx| {
 233                                     base::unsize_thin_ptr(bcx, lldata,
 234                                                           operand.ty, cast_ty)
 235                                 });
 236                                 OperandValue::FatPtr(lldata, llextra)
 237                             }
 238                             OperandValue::Ref(_) => {
 239                                 bcx.sess().bug(
 240                                     &format!("by-ref operand {} in trans_rvalue_operand",
 241                                              operand.repr(&bcx)));
 242                             }
 243                         }
 244                     }
 245                     mir::CastKind::Misc if common::type_is_immediate(bcx.ccx(), operand.ty) => {
 246                         debug_assert!(common::type_is_immediate(bcx.ccx(), cast_ty));
 247                         let r_t_in = CastTy::from_ty(operand.ty).expect("bad input type for cast");
 248                         let r_t_out = CastTy::from_ty(cast_ty).expect("bad output type for cast");
 249                         let ll_t_in = type_of::arg_type_of(bcx.ccx(), operand.ty);
 250                         let ll_t_out = type_of::arg_type_of(bcx.ccx(), cast_ty);
 251                         let (llval, ll_t_in, signed) = if let CastTy::Int(IntTy::CEnum) = r_t_in {
 252                             let repr = adt::represent_type(bcx.ccx(), operand.ty);
 253                             let llval = operand.immediate();
 254                             let discr = bcx.with_block(|bcx| {
 255                                 adt::trans_get_discr(bcx, &repr, llval, None, true)
 256                             });
 257                             (discr, common::val_ty(discr), adt::is_discr_signed(&repr))
 258                         } else {
 259                             (operand.immediate(), ll_t_in, operand.ty.is_signed())
 260                         };
 261
 262                         let newval = match (r_t_in, r_t_out) {
 263                             (CastTy::Int(_), CastTy::Int(_)) => {
 264                                 let srcsz = ll_t_in.int_width();
 265                                 let dstsz = ll_t_out.int_width();
 266                                 if srcsz == dstsz {
 267                                     bcx.bitcast(llval, ll_t_out)
 268                                 } else if srcsz > dstsz {
 269                                     bcx.trunc(llval, ll_t_out)
 270                                 } else if signed {
 271                                     bcx.sext(llval, ll_t_out)
 272                                 } else {
 273                                     bcx.zext(llval, ll_t_out)
 274                                 }
 275                             }
 276                             (CastTy::Float, CastTy::Float) => {
 277                                 let srcsz = ll_t_in.float_width();
 278                                 let dstsz = ll_t_out.float_width();
 279                                 if dstsz > srcsz {
 280                                     bcx.fpext(llval, ll_t_out)
 281                                 } else if srcsz > dstsz {
 282                                     bcx.fptrunc(llval, ll_t_out)
 283                                 } else {
 284                                     llval
 285                                 }
 286                             }
 287                             (CastTy::Ptr(_), CastTy::Ptr(_)) |
 288                             (CastTy::FnPtr, CastTy::Ptr(_)) |
 289                             (CastTy::RPtr(_), CastTy::Ptr(_)) =>
 290                                 bcx.pointercast(llval, ll_t_out),
 291                             (CastTy::Ptr(_), CastTy::Int(_)) |
 292                             (CastTy::FnPtr, CastTy::Int(_)) =>
 293                                 bcx.ptrtoint(llval, ll_t_out),
 294                             (CastTy::Int(_), CastTy::Ptr(_)) =>
 295                                 bcx.inttoptr(llval, ll_t_out),
 296                             (CastTy::Int(_), CastTy::Float) if signed =>
 297                                 bcx.sitofp(llval, ll_t_out),
 298                             (CastTy::Int(_), CastTy::Float) =>
 299                                 bcx.uitofp(llval, ll_t_out),
 300                             (CastTy::Float, CastTy::Int(IntTy::I)) =>
 301                                 bcx.fptosi(llval, ll_t_out),
 302                             (CastTy::Float, CastTy::Int(_)) =>
 303                                 bcx.fptoui(llval, ll_t_out),
 304                             _ => bcx.ccx().sess().bug(
 305                                 &format!("unsupported cast: {:?} to {:?}", operand.ty, cast_ty)
 306                             )
 307                         };
 308                         OperandValue::Immediate(newval)
 309                     }
 310                     mir::CastKind::Misc => { // Casts from a fat-ptr.
 311                         let ll_cast_ty = type_of::arg_type_of(bcx.ccx(), cast_ty);
 312                         let ll_from_ty = type_of::arg_type_of(bcx.ccx(), operand.ty);
 313                         if let OperandValue::FatPtr(data_ptr, meta_ptr) = operand.val {
 314                             if common::type_is_fat_ptr(bcx.tcx(), cast_ty) {
 315                                 let ll_cft = ll_cast_ty.field_types();
 316                                 let ll_fft = ll_from_ty.field_types();
 317                                 let data_cast = bcx.pointercast(data_ptr, ll_cft[0]);
 318                                 assert_eq!(ll_cft[1].kind(), ll_fft[1].kind());
 319                                 OperandValue::FatPtr(data_cast, meta_ptr)
 320                             } else { // cast to thin-ptr
 321                                 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
 322                                 // pointer-cast of that pointer to desired pointer type.
 323                                 let llval = bcx.pointercast(data_ptr, ll_cast_ty);
 324                                 OperandValue::Immediate(llval)
 325                             }
 326                         } else {
 327                             panic!("Unexpected non-FatPtr operand")
 328                         }
 329                     }
 330                 };
 331                 let operand = OperandRef {
 332                     val: val,
 333                     ty: cast_ty
 334                 };
 335                 (bcx, operand)
 336             }
 337
 338             mir::Rvalue::Ref(_, bk, ref lvalue) => {
 339                 let tr_lvalue = self.trans_lvalue(&bcx, lvalue);
 340
 341                 let ty = tr_lvalue.ty.to_ty(bcx.tcx());
 342                 let ref_ty = bcx.tcx().mk_ref(
 343                     bcx.tcx().mk_region(ty::ReStatic),
 344                     ty::TypeAndMut { ty: ty, mutbl: bk.to_mutbl_lossy() }
 345                 );
 346
 347                 // Note: lvalues are indirect, so storing the `llval` into the
 348                 // destination effectively creates a reference.
 349                 let operand = if common::type_is_sized(bcx.tcx(), ty) {
 350                     OperandRef {
 351                         val: OperandValue::Immediate(tr_lvalue.llval),
 352                         ty: ref_ty,
 353                     }
 354                 } else {
 355                     OperandRef {
 356                         val: OperandValue::FatPtr(tr_lvalue.llval,
 357                                                   tr_lvalue.llextra),
 358                         ty: ref_ty,
 359                     }
 360                 };
 361                 (bcx, operand)
 362             }
 363
 364             mir::Rvalue::Len(ref lvalue) => {
 365                 let tr_lvalue = self.trans_lvalue(&bcx, lvalue);
 366                 let operand = OperandRef {
 367                     val: OperandValue::Immediate(self.lvalue_len(&bcx, tr_lvalue)),
 368                     ty: bcx.tcx().types.usize,
 369                 };
 370                 (bcx, operand)
 371             }
 372
 373             mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 374                 let lhs = self.trans_operand(&bcx, lhs);
 375                 let rhs = self.trans_operand(&bcx, rhs);
 376                 let llresult = if common::type_is_fat_ptr(bcx.tcx(), lhs.ty) {
 377                     match (lhs.val, rhs.val) {
 378                         (OperandValue::FatPtr(lhs_addr, lhs_extra),
 379                          OperandValue::FatPtr(rhs_addr, rhs_extra)) => {
 380                             bcx.with_block(|bcx| {
 381                                 base::compare_fat_ptrs(bcx,
 382                                                        lhs_addr, lhs_extra,
 383                                                        rhs_addr, rhs_extra,
 384                                                        lhs.ty, op.to_hir_binop(),
 385                                                        DebugLoc::None)
 386                             })
 387                         }
 388                         _ => unreachable!()
 389                     }
 390
 391                 } else {
 392                     self.trans_scalar_binop(&bcx, op,
 393                                             lhs.immediate(), rhs.immediate(),
 394                                             lhs.ty)
 395                 };
 396                 let operand = OperandRef {
 397                     val: OperandValue::Immediate(llresult),
 398                     ty: self.mir.binop_ty(bcx.tcx(), op, lhs.ty, rhs.ty),
 399                 };
 400                 (bcx, operand)
 401             }
 402
 403             mir::Rvalue::UnaryOp(op, ref operand) => {
 404                 let operand = self.trans_operand(&bcx, operand);
 405                 let lloperand = operand.immediate();
 406                 let is_float = operand.ty.is_fp();
 407                 let llval = match op {
 408                     mir::UnOp::Not => bcx.not(lloperand),
 409                     mir::UnOp::Neg => if is_float {
 410                         bcx.fneg(lloperand)
 411                     } else {
 412                         bcx.neg(lloperand)
 413                     }
 414                 };
 415                 (bcx, OperandRef {
 416                     val: OperandValue::Immediate(llval),
 417                     ty: operand.ty,
 418                 })
 419             }
 420
 421             mir::Rvalue::Box(content_ty) => {
 422                 let content_ty: Ty<'tcx> = bcx.monomorphize(&content_ty);
 423                 let llty = type_of::type_of(bcx.ccx(), content_ty);
 424                 let llsize = machine::llsize_of(bcx.ccx(), llty);
 425                 let align = type_of::align_of(bcx.ccx(), content_ty);
 426                 let llalign = common::C_uint(bcx.ccx(), align);
 427                 let llty_ptr = llty.ptr_to();
 428                 let box_ty = bcx.tcx().mk_box(content_ty);
 429                 let mut llval = None;
 430                 let bcx = bcx.map_block(|bcx| {
 431                     let Result { bcx, val } = base::malloc_raw_dyn(bcx,
 432                                                                    llty_ptr,
 433                                                                    box_ty,
 434                                                                    llsize,
 435                                                                    llalign,
 436                                                                    DebugLoc::None);
 437                     llval = Some(val);
 438                     bcx
 439                 });
 440                 let operand = OperandRef {
 441                     val: OperandValue::Immediate(llval.unwrap()),
 442                     ty: box_ty,
 443                 };
 444                 (bcx, operand)
 445             }
 446
 447             mir::Rvalue::Use(..) |
 448             mir::Rvalue::Repeat(..) |
 449             mir::Rvalue::Aggregate(..) |
 450             mir::Rvalue::Slice { .. } |
 451             mir::Rvalue::InlineAsm(..) => {
 452                 bcx.tcx().sess.bug(&format!("cannot generate operand from rvalue {:?}", rvalue));
 453             }
 454         }
 455     }
 456
 457     pub fn trans_scalar_binop(&mut self,
 458                               bcx: &BlockAndBuilder<'bcx, 'tcx>,
 459                               op: mir::BinOp,
 460                               lhs: ValueRef,
 461                               rhs: ValueRef,
 462                               input_ty: Ty<'tcx>) -> ValueRef {
 463         let is_float = input_ty.is_fp();
 464         let is_signed = input_ty.is_signed();
 465         match op {
 466             mir::BinOp::Add => if is_float {
 467                 bcx.fadd(lhs, rhs)
 468             } else {
 469                 bcx.add(lhs, rhs)
 470             },
 471             mir::BinOp::Sub => if is_float {
 472                 bcx.fsub(lhs, rhs)
 473             } else {
 474                 bcx.sub(lhs, rhs)
 475             },
 476             mir::BinOp::Mul => if is_float {
 477                 bcx.fmul(lhs, rhs)
 478             } else {
 479                 bcx.mul(lhs, rhs)
 480             },
 481             mir::BinOp::Div => if is_float {
 482                 bcx.fdiv(lhs, rhs)
 483             } else if is_signed {
 484                 bcx.sdiv(lhs, rhs)
 485             } else {
 486                 bcx.udiv(lhs, rhs)
 487             },
 488             mir::BinOp::Rem => if is_float {
 489                 // LLVM currently always lowers the `frem` instructions appropriate
 490                 // library calls typically found in libm. Notably f64 gets wired up
 491                 // to `fmod` and f32 gets wired up to `fmodf`. Inconveniently for
 492                 // us, 32-bit MSVC does not actually have a `fmodf` symbol, it's
 493                 // instead just an inline function in a header that goes up to a
 494                 // f64, uses `fmod`, and then comes back down to a f32.
 495                 //
 496                 // Although LLVM knows that `fmodf` doesn't exist on MSVC, it will
 497                 // still unconditionally lower frem instructions over 32-bit floats
 498                 // to a call to `fmodf`. To work around this we special case MSVC
 499                 // 32-bit float rem instructions and instead do the call out to
 500                 // `fmod` ourselves.
 501                 //
 502                 // Note that this is currently duplicated with src/libcore/ops.rs
 503                 // which does the same thing, and it would be nice to perhaps unify
 504                 // these two implementations one day! Also note that we call `fmod`
 505                 // for both 32 and 64-bit floats because if we emit any FRem
 506                 // instruction at all then LLVM is capable of optimizing it into a
 507                 // 32-bit FRem (which we're trying to avoid).
 508                 let tcx = bcx.tcx();
 509                 let use_fmod = tcx.sess.target.target.options.is_like_msvc &&
 510                     tcx.sess.target.target.arch == "x86";
 511                 if use_fmod {
 512                     let f64t = Type::f64(bcx.ccx());
 513                     let fty = Type::func(&[f64t, f64t], &f64t);
 514                     let llfn = declare::declare_cfn(bcx.ccx(), "fmod", fty,
 515                                                     tcx.types.f64);
 516                     if input_ty == tcx.types.f32 {
 517                         let lllhs = bcx.fpext(lhs, f64t);
 518                         let llrhs = bcx.fpext(rhs, f64t);
 519                         let llres = bcx.call(llfn, &[lllhs, llrhs], None, None);
 520                         bcx.fptrunc(llres, Type::f32(bcx.ccx()))
 521                     } else {
 522                         bcx.call(llfn, &[lhs, rhs], None, None)
 523                     }
 524                 } else {
 525                     bcx.frem(lhs, rhs)
 526                 }
 527             } else if is_signed {
 528                 bcx.srem(lhs, rhs)
 529             } else {
 530                 bcx.urem(lhs, rhs)
 531             },
 532             mir::BinOp::BitOr => bcx.or(lhs, rhs),
 533             mir::BinOp::BitAnd => bcx.and(lhs, rhs),
 534             mir::BinOp::BitXor => bcx.xor(lhs, rhs),
 535             mir::BinOp::Shl => {
 536                 bcx.with_block(|bcx| {
 537                     common::build_unchecked_lshift(bcx,
 538                                                    lhs,
 539                                                    rhs,
 540                                                    DebugLoc::None)
 541                 })
 542             }
 543             mir::BinOp::Shr => {
 544                 bcx.with_block(|bcx| {
 545                     common::build_unchecked_rshift(bcx,
 546                                                    input_ty,
 547                                                    lhs,
 548                                                    rhs,
 549                                                    DebugLoc::None)
 550                 })
 551             }
 552             mir::BinOp::Eq | mir::BinOp::Lt | mir::BinOp::Gt |
 553             mir::BinOp::Ne | mir::BinOp::Le | mir::BinOp::Ge => {
 554                 bcx.with_block(|bcx| {
 555                     base::compare_scalar_types(bcx, lhs, rhs, input_ty,
 556                                                op.to_hir_binop(), DebugLoc::None)
 557                 })
 558             }
 559         }
 560     }
 561 }
 562
 563 pub fn rvalue_creates_operand<'tcx>(rvalue: &mir::Rvalue<'tcx>) -> bool {
 564     match *rvalue {
 565         mir::Rvalue::Ref(..) |
 566         mir::Rvalue::Len(..) |
 567         mir::Rvalue::Cast(..) | // (*)
 568         mir::Rvalue::BinaryOp(..) |
 569         mir::Rvalue::UnaryOp(..) |
 570         mir::Rvalue::Box(..) =>
 571             true,
 572         mir::Rvalue::Use(..) | // (**)
 573         mir::Rvalue::Repeat(..) |
 574         mir::Rvalue::Aggregate(..) |
 575         mir::Rvalue::Slice { .. } |
 576         mir::Rvalue::InlineAsm(..) =>
 577             false,
 578     }
 579
 580     // (*) this is only true if the type is suitable
 581     // (**) we need to zero-out the source operand after moving, so we are restricted to either
 582     // ensuring all users of `Use` zero it out themselves or not allowing to “create” operand for
 583     // it.
 584 }