lib/CodeGen/IntrinsicLowering.cpp

   1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the IntrinsicLowering class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Constants.h"
  15 #include "llvm/DerivedTypes.h"
  16 #include "llvm/Module.h"
  17 #include "llvm/Instructions.h"
  18 #include "llvm/Type.h"
  19 #include "llvm/CodeGen/IntrinsicLowering.h"
  20 #include "llvm/Support/Streams.h"
  21 using namespace llvm;
  22
  23 template <class ArgIt>
  24 static Function *EnsureFunctionExists(Module &M, const char *Name,
  25                                       ArgIt ArgBegin, ArgIt ArgEnd,
  26                                       const Type *RetTy) {
  27   if (Function *F = M.getNamedFunction(Name)) return F;
  28   // It doesn't already exist in the program, insert a new definition now.
  29   std::vector<const Type *> ParamTys;
  30   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  31     ParamTys.push_back(I->getType());
  32   return M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
  33 }
  34
  35 /// ReplaceCallWith - This function is used when we want to lower an intrinsic
  36 /// call to a call of an external function.  This handles hard cases such as
  37 /// when there was already a prototype for the external function, and if that
  38 /// prototype doesn't match the arguments we expect to pass in.
  39 template <class ArgIt>
  40 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
  41                                  ArgIt ArgBegin, ArgIt ArgEnd,
  42                                  const unsigned *castOpcodes,
  43                                  const Type *RetTy, Function *&FCache) {
  44   if (!FCache) {
  45     // If we haven't already looked up this function, check to see if the
  46     // program already contains a function with this name.
  47     Module *M = CI->getParent()->getParent()->getParent();
  48     FCache = M->getNamedFunction(NewFn);
  49     if (!FCache) {
  50       // It doesn't already exist in the program, insert a new definition now.
  51       std::vector<const Type *> ParamTys;
  52       for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  53         ParamTys.push_back((*I)->getType());
  54       FCache = M->getOrInsertFunction(NewFn,
  55                                      FunctionType::get(RetTy, ParamTys, false));
  56     }
  57    }
  58
  59   const FunctionType *FT = FCache->getFunctionType();
  60   std::vector<Value*> Operands;
  61   unsigned ArgNo = 0;
  62   for (ArgIt I = ArgBegin; I != ArgEnd && ArgNo != FT->getNumParams();
  63        ++I, ++ArgNo) {
  64     Value *Arg = *I;
  65     if (Arg->getType() != FT->getParamType(ArgNo))
  66       if (castOpcodes[ArgNo])
  67         Arg = CastInst::create(Instruction::CastOps(castOpcodes[ArgNo]),
  68           Arg, FT->getParamType(ArgNo), Arg->getName(), CI);
  69       else
  70         Arg = CastInst::createInferredCast(Arg, FT->getParamType(ArgNo),
  71                                            Arg->getName(), CI);
  72     Operands.push_back(Arg);
  73   }
  74   // Pass nulls into any additional arguments...
  75   for (; ArgNo != FT->getNumParams(); ++ArgNo)
  76     Operands.push_back(Constant::getNullValue(FT->getParamType(ArgNo)));
  77
  78   std::string Name = CI->getName(); CI->setName("");
  79   if (FT->getReturnType() == Type::VoidTy) Name.clear();
  80   CallInst *NewCI = new CallInst(FCache, Operands, Name, CI);
  81   if (!CI->use_empty()) {
  82     Value *V = NewCI;
  83     if (CI->getType() != NewCI->getType())
  84       V = CastInst::createInferredCast(NewCI, CI->getType(), Name, CI);
  85     CI->replaceAllUsesWith(V);
  86   }
  87   return NewCI;
  88 }
  89
  90 void IntrinsicLowering::AddPrototypes(Module &M) {
  91   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
  92     if (I->isExternal() && !I->use_empty())
  93       switch (I->getIntrinsicID()) {
  94       default: break;
  95       case Intrinsic::setjmp:
  96         EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
  97                              Type::IntTy);
  98         break;
  99       case Intrinsic::longjmp:
 100         EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
 101                              Type::VoidTy);
 102         break;
 103       case Intrinsic::siglongjmp:
 104         EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
 105                              Type::VoidTy);
 106         break;
 107       case Intrinsic::memcpy_i32:
 108       case Intrinsic::memcpy_i64:
 109         EnsureFunctionExists(M, "memcpy", I->arg_begin(), --I->arg_end(),
 110                              I->arg_begin()->getType());
 111         break;
 112       case Intrinsic::memmove_i32:
 113       case Intrinsic::memmove_i64:
 114         EnsureFunctionExists(M, "memmove", I->arg_begin(), --I->arg_end(),
 115                              I->arg_begin()->getType());
 116         break;
 117       case Intrinsic::memset_i32:
 118       case Intrinsic::memset_i64:
 119         M.getOrInsertFunction("memset", PointerType::get(Type::SByteTy),
 120                               PointerType::get(Type::SByteTy),
 121                               Type::IntTy, (--(--I->arg_end()))->getType(),
 122                               (Type *)0);
 123         break;
 124       case Intrinsic::isunordered_f32:
 125       case Intrinsic::isunordered_f64:
 126         EnsureFunctionExists(M, "isunordered", I->arg_begin(), I->arg_end(),
 127                              Type::BoolTy);
 128         break;
 129       case Intrinsic::sqrt_f32:
 130       case Intrinsic::sqrt_f64:
 131         if(I->arg_begin()->getType() == Type::FloatTy)
 132           EnsureFunctionExists(M, "sqrtf", I->arg_begin(), I->arg_end(),
 133                                Type::FloatTy);
 134         else
 135           EnsureFunctionExists(M, "sqrt", I->arg_begin(), I->arg_end(),
 136                                Type::DoubleTy);
 137         break;
 138       }
 139 }
 140
 141 /// LowerBSWAP - Emit the code to lower bswap of V before the specified
 142 /// instruction IP.
 143 static Value *LowerBSWAP(Value *V, Instruction *IP) {
 144   assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
 145
 146   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 147
 148   switch(BitSize) {
 149   default: assert(0 && "Unhandled type size of value to byteswap!");
 150   case 16: {
 151     Value *Tmp1 = new ShiftInst(Instruction::Shl, V,
 152                                 ConstantInt::get(Type::UByteTy,8),"bswap.2",IP);
 153     Value *Tmp2 = new ShiftInst(Instruction::LShr, V,
 154                                 ConstantInt::get(Type::UByteTy,8),"bswap.1",IP);
 155     V = BinaryOperator::createOr(Tmp1, Tmp2, "bswap.i16", IP);
 156     break;
 157   }
 158   case 32: {
 159     Value *Tmp4 = new ShiftInst(Instruction::Shl, V,
 160                               ConstantInt::get(Type::UByteTy,24),"bswap.4", IP);
 161     Value *Tmp3 = new ShiftInst(Instruction::Shl, V,
 162                               ConstantInt::get(Type::UByteTy,8),"bswap.3",IP);
 163     Value *Tmp2 = new ShiftInst(Instruction::LShr, V,
 164                               ConstantInt::get(Type::UByteTy,8),"bswap.2",IP);
 165     Value *Tmp1 = new ShiftInst(Instruction::LShr, V,
 166                               ConstantInt::get(Type::UByteTy,24),"bswap.1", IP);
 167     Tmp3 = BinaryOperator::createAnd(Tmp3,
 168                                      ConstantInt::get(Type::UIntTy, 0xFF0000),
 169                                      "bswap.and3", IP);
 170     Tmp2 = BinaryOperator::createAnd(Tmp2,
 171                                      ConstantInt::get(Type::UIntTy, 0xFF00),
 172                                      "bswap.and2", IP);
 173     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or1", IP);
 174     Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or2", IP);
 175     V = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.i32", IP);
 176     break;
 177   }
 178   case 64: {
 179     Value *Tmp8 = new ShiftInst(Instruction::Shl, V,
 180                               ConstantInt::get(Type::UByteTy,56),"bswap.8", IP);
 181     Value *Tmp7 = new ShiftInst(Instruction::Shl, V,
 182                               ConstantInt::get(Type::UByteTy,40),"bswap.7", IP);
 183     Value *Tmp6 = new ShiftInst(Instruction::Shl, V,
 184                               ConstantInt::get(Type::UByteTy,24),"bswap.6", IP);
 185     Value *Tmp5 = new ShiftInst(Instruction::Shl, V,
 186                               ConstantInt::get(Type::UByteTy,8),"bswap.5", IP);
 187     Value* Tmp4 = new ShiftInst(Instruction::LShr, V,
 188                               ConstantInt::get(Type::UByteTy,8),"bswap.4", IP);
 189     Value* Tmp3 = new ShiftInst(Instruction::LShr, V,
 190                               ConstantInt::get(Type::UByteTy,24),"bswap.3", IP);
 191     Value* Tmp2 = new ShiftInst(Instruction::LShr, V,
 192                               ConstantInt::get(Type::UByteTy,40),"bswap.2", IP);
 193     Value* Tmp1 = new ShiftInst(Instruction::LShr, V,
 194                               ConstantInt::get(Type::UByteTy,56),"bswap.1", IP);
 195     Tmp7 = BinaryOperator::createAnd(Tmp7,
 196                              ConstantInt::get(Type::ULongTy,
 197                                0xFF000000000000ULL),
 198                              "bswap.and7", IP);
 199     Tmp6 = BinaryOperator::createAnd(Tmp6,
 200                              ConstantInt::get(Type::ULongTy, 0xFF0000000000ULL),
 201                              "bswap.and6", IP);
 202     Tmp5 = BinaryOperator::createAnd(Tmp5,
 203                              ConstantInt::get(Type::ULongTy, 0xFF00000000ULL),
 204                              "bswap.and5", IP);
 205     Tmp4 = BinaryOperator::createAnd(Tmp4,
 206                              ConstantInt::get(Type::ULongTy, 0xFF000000ULL),
 207                              "bswap.and4", IP);
 208     Tmp3 = BinaryOperator::createAnd(Tmp3,
 209                              ConstantInt::get(Type::ULongTy, 0xFF0000ULL),
 210                              "bswap.and3", IP);
 211     Tmp2 = BinaryOperator::createAnd(Tmp2,
 212                              ConstantInt::get(Type::ULongTy, 0xFF00ULL),
 213                              "bswap.and2", IP);
 214     Tmp8 = BinaryOperator::createOr(Tmp8, Tmp7, "bswap.or1", IP);
 215     Tmp6 = BinaryOperator::createOr(Tmp6, Tmp5, "bswap.or2", IP);
 216     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or3", IP);
 217     Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or4", IP);
 218     Tmp8 = BinaryOperator::createOr(Tmp8, Tmp6, "bswap.or5", IP);
 219     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp2, "bswap.or6", IP);
 220     V = BinaryOperator::createOr(Tmp8, Tmp4, "bswap.i64", IP);
 221     break;
 222   }
 223   }
 224   return V;
 225 }
 226
 227 /// LowerCTPOP - Emit the code to lower ctpop of V before the specified
 228 /// instruction IP.
 229 static Value *LowerCTPOP(Value *V, Instruction *IP) {
 230   assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
 231
 232   static const uint64_t MaskValues[6] = {
 233     0x5555555555555555ULL, 0x3333333333333333ULL,
 234     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
 235     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
 236   };
 237
 238   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 239
 240   for (unsigned i = 1, ct = 0; i != BitSize; i <<= 1, ++ct) {
 241     Value *MaskCst =
 242       ConstantExpr::getCast(ConstantInt::get(Type::ULongTy, MaskValues[ct]),
 243                                              V->getType());
 244     Value *LHS = BinaryOperator::createAnd(V, MaskCst, "cppop.and1", IP);
 245     Value *VShift = new ShiftInst(Instruction::LShr, V,
 246                       ConstantInt::get(Type::UByteTy, i), "ctpop.sh", IP);
 247     Value *RHS = BinaryOperator::createAnd(VShift, MaskCst, "cppop.and2", IP);
 248     V = BinaryOperator::createAdd(LHS, RHS, "ctpop.step", IP);
 249   }
 250
 251   return V;
 252 }
 253
 254 /// LowerCTLZ - Emit the code to lower ctlz of V before the specified
 255 /// instruction IP.
 256 static Value *LowerCTLZ(Value *V, Instruction *IP) {
 257
 258   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 259   for (unsigned i = 1; i != BitSize; i <<= 1) {
 260     Value *ShVal = ConstantInt::get(Type::UByteTy, i);
 261     ShVal = new ShiftInst(Instruction::LShr, V, ShVal, "ctlz.sh", IP);
 262     V = BinaryOperator::createOr(V, ShVal, "ctlz.step", IP);
 263   }
 264
 265   V = BinaryOperator::createNot(V, "", IP);
 266   return LowerCTPOP(V, IP);
 267 }
 268
 269
 270
 271 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
 272   Function *Callee = CI->getCalledFunction();
 273   assert(Callee && "Cannot lower an indirect call!");
 274
 275   switch (Callee->getIntrinsicID()) {
 276   case Intrinsic::not_intrinsic:
 277     llvm_cerr << "Cannot lower a call to a non-intrinsic function '"
 278               << Callee->getName() << "'!\n";
 279     abort();
 280   default:
 281     llvm_cerr << "Error: Code generator does not support intrinsic function '"
 282               << Callee->getName() << "'!\n";
 283     abort();
 284
 285     // The setjmp/longjmp intrinsics should only exist in the code if it was
 286     // never optimized (ie, right out of the CFE), or if it has been hacked on
 287     // by the lowerinvoke pass.  In both cases, the right thing to do is to
 288     // convert the call to an explicit setjmp or longjmp call.
 289   case Intrinsic::setjmp: {
 290     static Function *SetjmpFCache = 0;
 291     static const unsigned castOpcodes[] = { Instruction::BitCast };
 292     Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin()+1, CI->op_end(),
 293                                castOpcodes, Type::IntTy, SetjmpFCache);
 294     if (CI->getType() != Type::VoidTy)
 295       CI->replaceAllUsesWith(V);
 296     break;
 297   }
 298   case Intrinsic::sigsetjmp:
 299      if (CI->getType() != Type::VoidTy)
 300        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 301      break;
 302
 303   case Intrinsic::longjmp: {
 304     static Function *LongjmpFCache = 0;
 305     static const unsigned castOpcodes[] =
 306       { Instruction::BitCast, 0 };
 307     ReplaceCallWith("longjmp", CI, CI->op_begin()+1, CI->op_end(),
 308                     castOpcodes, Type::VoidTy, LongjmpFCache);
 309     break;
 310   }
 311
 312   case Intrinsic::siglongjmp: {
 313     // Insert the call to abort
 314     static Function *AbortFCache = 0;
 315     static const unsigned castOpcodes[] =
 316       { Instruction::BitCast, 0 };
 317     ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
 318                     castOpcodes, Type::VoidTy, AbortFCache);
 319     break;
 320   }
 321   case Intrinsic::ctpop_i8:
 322   case Intrinsic::ctpop_i16:
 323   case Intrinsic::ctpop_i32:
 324   case Intrinsic::ctpop_i64:
 325     CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
 326     break;
 327
 328   case Intrinsic::bswap_i16:
 329   case Intrinsic::bswap_i32:
 330   case Intrinsic::bswap_i64:
 331     CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
 332     break;
 333
 334   case Intrinsic::ctlz_i8:
 335   case Intrinsic::ctlz_i16:
 336   case Intrinsic::ctlz_i32:
 337   case Intrinsic::ctlz_i64:
 338     CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
 339     break;
 340
 341   case Intrinsic::cttz_i8:
 342   case Intrinsic::cttz_i16:
 343   case Intrinsic::cttz_i32:
 344   case Intrinsic::cttz_i64: {
 345     // cttz(x) -> ctpop(~X & (X-1))
 346     Value *Src = CI->getOperand(1);
 347     Value *NotSrc = BinaryOperator::createNot(Src, Src->getName()+".not", CI);
 348     Value *SrcM1  = ConstantInt::get(Src->getType(), 1);
 349     SrcM1 = BinaryOperator::createSub(Src, SrcM1, "", CI);
 350     Src = LowerCTPOP(BinaryOperator::createAnd(NotSrc, SrcM1, "", CI), CI);
 351     CI->replaceAllUsesWith(Src);
 352     break;
 353   }
 354
 355   case Intrinsic::stacksave:
 356   case Intrinsic::stackrestore: {
 357     static bool Warned = false;
 358     if (!Warned)
 359       llvm_cerr << "WARNING: this target does not support the llvm.stack"
 360                 << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
 361                     "save" : "restore") << " intrinsic.\n";
 362     Warned = true;
 363     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
 364       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 365     break;
 366   }
 367
 368   case Intrinsic::returnaddress:
 369   case Intrinsic::frameaddress:
 370     llvm_cerr << "WARNING: this target does not support the llvm."
 371               << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
 372                   "return" : "frame") << "address intrinsic.\n";
 373     CI->replaceAllUsesWith(ConstantPointerNull::get(
 374                                             cast<PointerType>(CI->getType())));
 375     break;
 376
 377   case Intrinsic::prefetch:
 378     break;    // Simply strip out prefetches on unsupported architectures
 379
 380   case Intrinsic::pcmarker:
 381     break;    // Simply strip out pcmarker on unsupported architectures
 382   case Intrinsic::readcyclecounter: {
 383     llvm_cerr << "WARNING: this target does not support the llvm.readcyclecoun"
 384               << "ter intrinsic.  It is being lowered to a constant 0\n";
 385     CI->replaceAllUsesWith(ConstantInt::get(Type::ULongTy, 0));
 386     break;
 387   }
 388
 389   case Intrinsic::dbg_stoppoint:
 390   case Intrinsic::dbg_region_start:
 391   case Intrinsic::dbg_region_end:
 392   case Intrinsic::dbg_func_start:
 393   case Intrinsic::dbg_declare:
 394     break;    // Simply strip out debugging intrinsics
 395
 396   case Intrinsic::memcpy_i32: {
 397     // The memcpy intrinsic take an extra alignment argument that the memcpy
 398     // libc function does not.
 399     static unsigned opcodes[] =
 400       { Instruction::BitCast, Instruction::BitCast, Instruction::BitCast };
 401     // FIXME:
 402     // if (target_is_64_bit) opcodes[2] = Instruction::ZExt;
 403     // else opcodes[2] = Instruction::BitCast;
 404     static Function *MemcpyFCache = 0;
 405     ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
 406                     opcodes, (*(CI->op_begin()+1))->getType(), MemcpyFCache);
 407     break;
 408   }
 409   case Intrinsic::memcpy_i64: {
 410     static unsigned opcodes[] =
 411       { Instruction::BitCast, Instruction::BitCast, Instruction::Trunc };
 412     // FIXME:
 413     // if (target_is_64_bit) opcodes[2] = Instruction::BitCast;
 414     // else opcodes[2] = Instruction::Trunc;
 415     static Function *MemcpyFCache = 0;
 416     ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
 417                      opcodes, (*(CI->op_begin()+1))->getType(), MemcpyFCache);
 418     break;
 419   }
 420   case Intrinsic::memmove_i32: {
 421     // The memmove intrinsic take an extra alignment argument that the memmove
 422     // libc function does not.
 423     static unsigned opcodes[] =
 424       { Instruction::BitCast, Instruction::BitCast, Instruction::BitCast };
 425     // FIXME:
 426     // if (target_is_64_bit) opcodes[2] = Instruction::ZExt;
 427     // else opcodes[2] = Instruction::BitCast;
 428     static Function *MemmoveFCache = 0;
 429     ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
 430                     opcodes, (*(CI->op_begin()+1))->getType(), MemmoveFCache);
 431     break;
 432   }
 433   case Intrinsic::memmove_i64: {
 434     // The memmove intrinsic take an extra alignment argument that the memmove
 435     // libc function does not.
 436     static const unsigned opcodes[] =
 437       { Instruction::BitCast, Instruction::BitCast, Instruction::Trunc };
 438     // if (target_is_64_bit) opcodes[2] = Instruction::BitCast;
 439     // else opcodes[2] = Instruction::Trunc;
 440     static Function *MemmoveFCache = 0;
 441     ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
 442                     opcodes, (*(CI->op_begin()+1))->getType(), MemmoveFCache);
 443     break;
 444   }
 445   case Intrinsic::memset_i32: {
 446     // The memset intrinsic take an extra alignment argument that the memset
 447     // libc function does not.
 448     static const unsigned opcodes[] =
 449       { Instruction::BitCast, Instruction::ZExt, Instruction::ZExt, 0 };
 450     // if (target_is_64_bit) opcodes[2] = Instruction::BitCast;
 451     // else opcodes[2] = Instruction::ZExt;
 452     static Function *MemsetFCache = 0;
 453     ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
 454                     opcodes, (*(CI->op_begin()+1))->getType(), MemsetFCache);
 455   }
 456   case Intrinsic::memset_i64: {
 457     // The memset intrinsic take an extra alignment argument that the memset
 458     // libc function does not.
 459     static const unsigned opcodes[] =
 460       { Instruction::BitCast, Instruction::ZExt, Instruction::Trunc, 0 };
 461     // if (target_is_64_bit) opcodes[2] = Instruction::BitCast;
 462     // else opcodes[2] = Instruction::Trunc;
 463     static Function *MemsetFCache = 0;
 464     ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
 465                     opcodes, (*(CI->op_begin()+1))->getType(), MemsetFCache);
 466     break;
 467   }
 468   case Intrinsic::isunordered_f32:
 469   case Intrinsic::isunordered_f64: {
 470     Value *L = CI->getOperand(1);
 471     Value *R = CI->getOperand(2);
 472
 473     Value *LIsNan = new SetCondInst(Instruction::SetNE, L, L, "LIsNan", CI);
 474     Value *RIsNan = new SetCondInst(Instruction::SetNE, R, R, "RIsNan", CI);
 475     CI->replaceAllUsesWith(
 476       BinaryOperator::create(Instruction::Or, LIsNan, RIsNan,
 477                              "isunordered", CI));
 478     break;
 479   }
 480   case Intrinsic::sqrt_f32: {
 481     static const unsigned opcodes[] = { 0 };
 482     static Function *sqrtfFCache = 0;
 483     ReplaceCallWith("sqrtf", CI, CI->op_begin()+1, CI->op_end(),
 484                     opcodes, Type::FloatTy, sqrtfFCache);
 485     break;
 486   }
 487   case Intrinsic::sqrt_f64: {
 488     static const unsigned opcodes[] =  { 0 };
 489     static Function *sqrtFCache = 0;
 490     ReplaceCallWith("sqrt", CI, CI->op_begin()+1, CI->op_end(),
 491                     opcodes, Type::DoubleTy, sqrtFCache);
 492     break;
 493   }
 494   }
 495
 496   assert(CI->use_empty() &&
 497          "Lowering should have eliminated any uses of the intrinsic call!");
 498   CI->eraseFromParent();
 499 }