lib/CodeGen/IntrinsicLowering.cpp

   1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // 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/Type.h"
  18 #include "llvm/CodeGen/IntrinsicLowering.h"
  19 #include "llvm/Support/IRBuilder.h"
  20 #include "llvm/Support/ErrorHandling.h"
  21 #include "llvm/Target/TargetData.h"
  22 #include "llvm/ADT/SmallVector.h"
  23 using namespace llvm;
  24
  25 template <class ArgIt>
  26 static void EnsureFunctionExists(Module &M, const char *Name,
  27                                  ArgIt ArgBegin, ArgIt ArgEnd,
  28                                  const Type *RetTy) {
  29   // Insert a correctly-typed definition now.
  30   std::vector<const Type *> ParamTys;
  31   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  32     ParamTys.push_back(I->getType());
  33   M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
  34 }
  35
  36 static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
  37                                     const char *FName,
  38                                     const char *DName, const char *LDName) {
  39   // Insert definitions for all the floating point types.
  40   switch((int)Fn->arg_begin()->getType()->getTypeID()) {
  41   case Type::FloatTyID:
  42     EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
  43                          Type::getFloatTy(M.getContext()));
  44     break;
  45   case Type::DoubleTyID:
  46     EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
  47                          Type::getDoubleTy(M.getContext()));
  48     break;
  49   case Type::X86_FP80TyID:
  50   case Type::FP128TyID:
  51   case Type::PPC_FP128TyID:
  52     EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
  53                          Fn->arg_begin()->getType());
  54     break;
  55   }
  56 }
  57
  58 /// ReplaceCallWith - This function is used when we want to lower an intrinsic
  59 /// call to a call of an external function.  This handles hard cases such as
  60 /// when there was already a prototype for the external function, and if that
  61 /// prototype doesn't match the arguments we expect to pass in.
  62 template <class ArgIt>
  63 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
  64                                  ArgIt ArgBegin, ArgIt ArgEnd,
  65                                  const Type *RetTy) {
  66   // If we haven't already looked up this function, check to see if the
  67   // program already contains a function with this name.
  68   Module *M = CI->getParent()->getParent()->getParent();
  69   // Get or insert the definition now.
  70   std::vector<const Type *> ParamTys;
  71   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  72     ParamTys.push_back((*I)->getType());
  73   Constant* FCache = M->getOrInsertFunction(NewFn,
  74                                   FunctionType::get(RetTy, ParamTys, false));
  75
  76   IRBuilder<> Builder(CI->getParent(), CI);
  77   SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
  78   CallInst *NewCI = Builder.CreateCall(FCache, Args.begin(), Args.end());
  79   NewCI->setName(CI->getName());
  80   if (!CI->use_empty())
  81     CI->replaceAllUsesWith(NewCI);
  82   return NewCI;
  83 }
  84
  85 void IntrinsicLowering::AddPrototypes(Module &M) {
  86   LLVMContext &Context = M.getContext();
  87   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
  88     if (I->isDeclaration() && !I->use_empty())
  89       switch (I->getIntrinsicID()) {
  90       default: break;
  91       case Intrinsic::setjmp:
  92         EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
  93                              Type::getInt32Ty(M.getContext()));
  94         break;
  95       case Intrinsic::longjmp:
  96         EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
  97                              Type::getVoidTy(M.getContext()));
  98         break;
  99       case Intrinsic::siglongjmp:
 100         EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
 101                              Type::getVoidTy(M.getContext()));
 102         break;
 103       case Intrinsic::memcpy:
 104         M.getOrInsertFunction("memcpy",
 105           PointerType::getUnqual(Type::getInt8Ty(Context)),
 106                               PointerType::getUnqual(Type::getInt8Ty(Context)),
 107                               PointerType::getUnqual(Type::getInt8Ty(Context)),
 108                               TD.getIntPtrType(Context), (Type *)0);
 109         break;
 110       case Intrinsic::memmove:
 111         M.getOrInsertFunction("memmove",
 112           PointerType::getUnqual(Type::getInt8Ty(Context)),
 113                               PointerType::getUnqual(Type::getInt8Ty(Context)),
 114                               PointerType::getUnqual(Type::getInt8Ty(Context)),
 115                               TD.getIntPtrType(Context), (Type *)0);
 116         break;
 117       case Intrinsic::memset:
 118         M.getOrInsertFunction("memset",
 119           PointerType::getUnqual(Type::getInt8Ty(Context)),
 120                               PointerType::getUnqual(Type::getInt8Ty(Context)),
 121                               Type::getInt32Ty(M.getContext()),
 122                               TD.getIntPtrType(Context), (Type *)0);
 123         break;
 124       case Intrinsic::sqrt:
 125         EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
 126         break;
 127       case Intrinsic::sin:
 128         EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
 129         break;
 130       case Intrinsic::cos:
 131         EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
 132         break;
 133       case Intrinsic::pow:
 134         EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
 135         break;
 136       case Intrinsic::log:
 137         EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
 138         break;
 139       case Intrinsic::log2:
 140         EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
 141         break;
 142       case Intrinsic::log10:
 143         EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
 144         break;
 145       case Intrinsic::exp:
 146         EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
 147         break;
 148       case Intrinsic::exp2:
 149         EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
 150         break;
 151       }
 152 }
 153
 154 /// LowerBSWAP - Emit the code to lower bswap of V before the specified
 155 /// instruction IP.
 156 static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
 157   assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
 158
 159   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 160
 161   IRBuilder<> Builder(IP->getParent(), IP);
 162
 163   switch(BitSize) {
 164   default: llvm_unreachable("Unhandled type size of value to byteswap!");
 165   case 16: {
 166     Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 167                                     "bswap.2");
 168     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 169                                      "bswap.1");
 170     V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
 171     break;
 172   }
 173   case 32: {
 174     Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
 175                                     "bswap.4");
 176     Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 177                                     "bswap.3");
 178     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 179                                      "bswap.2");
 180     Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
 181                                      "bswap.1");
 182     Tmp3 = Builder.CreateAnd(Tmp3,
 183                          ConstantInt::get(Type::getInt32Ty(Context), 0xFF0000),
 184                              "bswap.and3");
 185     Tmp2 = Builder.CreateAnd(Tmp2,
 186                            ConstantInt::get(Type::getInt32Ty(Context), 0xFF00),
 187                              "bswap.and2");
 188     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
 189     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
 190     V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
 191     break;
 192   }
 193   case 64: {
 194     Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
 195                                     "bswap.8");
 196     Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
 197                                     "bswap.7");
 198     Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
 199                                     "bswap.6");
 200     Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 201                                     "bswap.5");
 202     Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 203                                      "bswap.4");
 204     Value* Tmp3 = Builder.CreateLShr(V,
 205                                      ConstantInt::get(V->getType(), 24),
 206                                      "bswap.3");
 207     Value* Tmp2 = Builder.CreateLShr(V,
 208                                      ConstantInt::get(V->getType(), 40),
 209                                      "bswap.2");
 210     Value* Tmp1 = Builder.CreateLShr(V,
 211                                      ConstantInt::get(V->getType(), 56),
 212                                      "bswap.1");
 213     Tmp7 = Builder.CreateAnd(Tmp7,
 214                              ConstantInt::get(Type::getInt64Ty(Context),
 215                                               0xFF000000000000ULL),
 216                              "bswap.and7");
 217     Tmp6 = Builder.CreateAnd(Tmp6,
 218                              ConstantInt::get(Type::getInt64Ty(Context),
 219                                               0xFF0000000000ULL),
 220                              "bswap.and6");
 221     Tmp5 = Builder.CreateAnd(Tmp5,
 222                         ConstantInt::get(Type::getInt64Ty(Context),
 223                              0xFF00000000ULL),
 224                              "bswap.and5");
 225     Tmp4 = Builder.CreateAnd(Tmp4,
 226                         ConstantInt::get(Type::getInt64Ty(Context),
 227                              0xFF000000ULL),
 228                              "bswap.and4");
 229     Tmp3 = Builder.CreateAnd(Tmp3,
 230                              ConstantInt::get(Type::getInt64Ty(Context),
 231                              0xFF0000ULL),
 232                              "bswap.and3");
 233     Tmp2 = Builder.CreateAnd(Tmp2,
 234                              ConstantInt::get(Type::getInt64Ty(Context),
 235                              0xFF00ULL),
 236                              "bswap.and2");
 237     Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
 238     Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
 239     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
 240     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
 241     Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
 242     Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
 243     V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
 244     break;
 245   }
 246   }
 247   return V;
 248 }
 249
 250 /// LowerCTPOP - Emit the code to lower ctpop of V before the specified
 251 /// instruction IP.
 252 static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
 253   assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
 254
 255   static const uint64_t MaskValues[6] = {
 256     0x5555555555555555ULL, 0x3333333333333333ULL,
 257     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
 258     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
 259   };
 260
 261   IRBuilder<> Builder(IP->getParent(), IP);
 262
 263   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 264   unsigned WordSize = (BitSize + 63) / 64;
 265   Value *Count = ConstantInt::get(V->getType(), 0);
 266
 267   for (unsigned n = 0; n < WordSize; ++n) {
 268     Value *PartValue = V;
 269     for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
 270          i <<= 1, ++ct) {
 271       Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
 272       Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
 273       Value *VShift = Builder.CreateLShr(PartValue,
 274                                         ConstantInt::get(V->getType(), i),
 275                                          "ctpop.sh");
 276       Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
 277       PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
 278     }
 279     Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
 280     if (BitSize > 64) {
 281       V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
 282                              "ctpop.part.sh");
 283       BitSize -= 64;
 284     }
 285   }
 286
 287   return Count;
 288 }
 289
 290 /// LowerCTLZ - Emit the code to lower ctlz of V before the specified
 291 /// instruction IP.
 292 static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
 293
 294   IRBuilder<> Builder(IP->getParent(), IP);
 295
 296   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 297   for (unsigned i = 1; i < BitSize; i <<= 1) {
 298     Value *ShVal = ConstantInt::get(V->getType(), i);
 299     ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
 300     V = Builder.CreateOr(V, ShVal, "ctlz.step");
 301   }
 302
 303   V = Builder.CreateNot(V);
 304   return LowerCTPOP(Context, V, IP);
 305 }
 306
 307 static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
 308                                        const char *Dname,
 309                                        const char *LDname) {
 310   switch (CI->getOperand(1)->getType()->getTypeID()) {
 311   default: llvm_unreachable("Invalid type in intrinsic");
 312   case Type::FloatTyID:
 313     ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
 314                   Type::getFloatTy(CI->getContext()));
 315     break;
 316   case Type::DoubleTyID:
 317     ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
 318                   Type::getDoubleTy(CI->getContext()));
 319     break;
 320   case Type::X86_FP80TyID:
 321   case Type::FP128TyID:
 322   case Type::PPC_FP128TyID:
 323     ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
 324                   CI->getOperand(1)->getType());
 325     break;
 326   }
 327 }
 328
 329 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
 330   IRBuilder<> Builder(CI->getParent(), CI);
 331   LLVMContext &Context = CI->getContext();
 332
 333   Function *Callee = CI->getCalledFunction();
 334   assert(Callee && "Cannot lower an indirect call!");
 335
 336   switch (Callee->getIntrinsicID()) {
 337   case Intrinsic::not_intrinsic:
 338     llvm_report_error("Cannot lower a call to a non-intrinsic function '"+
 339                       Callee->getName() + "'!");
 340   default:
 341     llvm_report_error("Code generator does not support intrinsic function '"+
 342                       Callee->getName()+"'!");
 343
 344     // The setjmp/longjmp intrinsics should only exist in the code if it was
 345     // never optimized (ie, right out of the CFE), or if it has been hacked on
 346     // by the lowerinvoke pass.  In both cases, the right thing to do is to
 347     // convert the call to an explicit setjmp or longjmp call.
 348   case Intrinsic::setjmp: {
 349     Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
 350                                Type::getInt32Ty(Context));
 351     if (CI->getType() != Type::getVoidTy(Context))
 352       CI->replaceAllUsesWith(V);
 353     break;
 354   }
 355   case Intrinsic::sigsetjmp:
 356      if (CI->getType() != Type::getVoidTy(Context))
 357        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 358      break;
 359
 360   case Intrinsic::longjmp: {
 361     ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
 362                     Type::getVoidTy(Context));
 363     break;
 364   }
 365
 366   case Intrinsic::siglongjmp: {
 367     // Insert the call to abort
 368     ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
 369                     Type::getVoidTy(Context));
 370     break;
 371   }
 372   case Intrinsic::ctpop:
 373     CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getOperand(1), CI));
 374     break;
 375
 376   case Intrinsic::bswap:
 377     CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getOperand(1), CI));
 378     break;
 379
 380   case Intrinsic::ctlz:
 381     CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getOperand(1), CI));
 382     break;
 383
 384   case Intrinsic::cttz: {
 385     // cttz(x) -> ctpop(~X & (X-1))
 386     Value *Src = CI->getOperand(1);
 387     Value *NotSrc = Builder.CreateNot(Src);
 388     NotSrc->setName(Src->getName() + ".not");
 389     Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
 390     SrcM1 = Builder.CreateSub(Src, SrcM1);
 391     Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
 392     CI->replaceAllUsesWith(Src);
 393     break;
 394   }
 395
 396   case Intrinsic::stacksave:
 397   case Intrinsic::stackrestore: {
 398     if (!Warned)
 399       cerr << "WARNING: this target does not support the llvm.stack"
 400            << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
 401                "save" : "restore") << " intrinsic.\n";
 402     Warned = true;
 403     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
 404       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 405     break;
 406   }
 407
 408   case Intrinsic::returnaddress:
 409   case Intrinsic::frameaddress:
 410     cerr << "WARNING: this target does not support the llvm."
 411          << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
 412              "return" : "frame") << "address intrinsic.\n";
 413     CI->replaceAllUsesWith(ConstantPointerNull::get(
 414                                             cast<PointerType>(CI->getType())));
 415     break;
 416
 417   case Intrinsic::prefetch:
 418     break;    // Simply strip out prefetches on unsupported architectures
 419
 420   case Intrinsic::pcmarker:
 421     break;    // Simply strip out pcmarker on unsupported architectures
 422   case Intrinsic::readcyclecounter: {
 423     cerr << "WARNING: this target does not support the llvm.readcyclecoun"
 424          << "ter intrinsic.  It is being lowered to a constant 0\n";
 425     CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
 426     break;
 427   }
 428
 429   case Intrinsic::dbg_stoppoint:
 430   case Intrinsic::dbg_region_start:
 431   case Intrinsic::dbg_region_end:
 432   case Intrinsic::dbg_func_start:
 433   case Intrinsic::dbg_declare:
 434     break;    // Simply strip out debugging intrinsics
 435
 436   case Intrinsic::eh_exception:
 437   case Intrinsic::eh_selector_i32:
 438   case Intrinsic::eh_selector_i64:
 439     CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 440     break;
 441
 442   case Intrinsic::eh_typeid_for_i32:
 443   case Intrinsic::eh_typeid_for_i64:
 444     // Return something different to eh_selector.
 445     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 446     break;
 447
 448   case Intrinsic::var_annotation:
 449     break;   // Strip out annotate intrinsic
 450
 451   case Intrinsic::memcpy: {
 452     const IntegerType *IntPtr = TD.getIntPtrType(Context);
 453     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 454                                         /* isSigned */ false);
 455     Value *Ops[3];
 456     Ops[0] = CI->getOperand(1);
 457     Ops[1] = CI->getOperand(2);
 458     Ops[2] = Size;
 459     ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType());
 460     break;
 461   }
 462   case Intrinsic::memmove: {
 463     const IntegerType *IntPtr = TD.getIntPtrType(Context);
 464     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 465                                         /* isSigned */ false);
 466     Value *Ops[3];
 467     Ops[0] = CI->getOperand(1);
 468     Ops[1] = CI->getOperand(2);
 469     Ops[2] = Size;
 470     ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType());
 471     break;
 472   }
 473   case Intrinsic::memset: {
 474     const IntegerType *IntPtr = TD.getIntPtrType(Context);
 475     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 476                                         /* isSigned */ false);
 477     Value *Ops[3];
 478     Ops[0] = CI->getOperand(1);
 479     // Extend the amount to i32.
 480     Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::getInt32Ty(Context),
 481                                    /* isSigned */ false);
 482     Ops[2] = Size;
 483     ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType());
 484     break;
 485   }
 486   case Intrinsic::sqrt: {
 487     ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
 488     break;
 489   }
 490   case Intrinsic::log: {
 491     ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
 492     break;
 493   }
 494   case Intrinsic::log2: {
 495     ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
 496     break;
 497   }
 498   case Intrinsic::log10: {
 499     ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
 500     break;
 501   }
 502   case Intrinsic::exp: {
 503     ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
 504     break;
 505   }
 506   case Intrinsic::exp2: {
 507     ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
 508     break;
 509   }
 510   case Intrinsic::pow: {
 511     ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
 512     break;
 513   }
 514   case Intrinsic::flt_rounds:
 515      // Lower to "round to the nearest"
 516      if (CI->getType() != Type::getVoidTy(Context))
 517        CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 518      break;
 519   }
 520
 521   assert(CI->use_empty() &&
 522          "Lowering should have eliminated any uses of the intrinsic call!");
 523   CI->eraseFromParent();
 524 }