LLVM API Documentation

IntrinsicLowering.cpp
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00001 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file is distributed under the University of Illinois Open Source
00006 // License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements the IntrinsicLowering class.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #include "llvm/CodeGen/IntrinsicLowering.h"
00015 #include "llvm/ADT/SmallVector.h"
00016 #include "llvm/IR/CallSite.h"
00017 #include "llvm/IR/Constants.h"
00018 #include "llvm/IR/DataLayout.h"
00019 #include "llvm/IR/DerivedTypes.h"
00020 #include "llvm/IR/IRBuilder.h"
00021 #include "llvm/IR/Module.h"
00022 #include "llvm/IR/Type.h"
00023 #include "llvm/Support/ErrorHandling.h"
00024 #include "llvm/Support/raw_ostream.h"
00025 using namespace llvm;
00026 
00027 template <class ArgIt>
00028 static void EnsureFunctionExists(Module &M, const char *Name,
00029                                  ArgIt ArgBegin, ArgIt ArgEnd,
00030                                  Type *RetTy) {
00031   // Insert a correctly-typed definition now.
00032   std::vector<Type *> ParamTys;
00033   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
00034     ParamTys.push_back(I->getType());
00035   M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
00036 }
00037 
00038 static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
00039                                     const char *FName,
00040                                     const char *DName, const char *LDName) {
00041   // Insert definitions for all the floating point types.
00042   switch((int)Fn->arg_begin()->getType()->getTypeID()) {
00043   case Type::FloatTyID:
00044     EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
00045                          Type::getFloatTy(M.getContext()));
00046     break;
00047   case Type::DoubleTyID:
00048     EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
00049                          Type::getDoubleTy(M.getContext()));
00050     break;
00051   case Type::X86_FP80TyID:
00052   case Type::FP128TyID:
00053   case Type::PPC_FP128TyID:
00054     EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
00055                          Fn->arg_begin()->getType());
00056     break;
00057   }
00058 }
00059 
00060 /// ReplaceCallWith - This function is used when we want to lower an intrinsic
00061 /// call to a call of an external function.  This handles hard cases such as
00062 /// when there was already a prototype for the external function, and if that
00063 /// prototype doesn't match the arguments we expect to pass in.
00064 template <class ArgIt>
00065 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
00066                                  ArgIt ArgBegin, ArgIt ArgEnd,
00067                                  Type *RetTy) {
00068   // If we haven't already looked up this function, check to see if the
00069   // program already contains a function with this name.
00070   Module *M = CI->getParent()->getParent()->getParent();
00071   // Get or insert the definition now.
00072   std::vector<Type *> ParamTys;
00073   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
00074     ParamTys.push_back((*I)->getType());
00075   Constant* FCache = M->getOrInsertFunction(NewFn,
00076                                   FunctionType::get(RetTy, ParamTys, false));
00077 
00078   IRBuilder<> Builder(CI->getParent(), CI);
00079   SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
00080   CallInst *NewCI = Builder.CreateCall(FCache, Args);
00081   NewCI->setName(CI->getName());
00082   if (!CI->use_empty())
00083     CI->replaceAllUsesWith(NewCI);
00084   return NewCI;
00085 }
00086 
00087 // VisualStudio defines setjmp as _setjmp
00088 #if defined(_MSC_VER) && defined(setjmp) && \
00089                          !defined(setjmp_undefined_for_msvc)
00090 #  pragma push_macro("setjmp")
00091 #  undef setjmp
00092 #  define setjmp_undefined_for_msvc
00093 #endif
00094 
00095 void IntrinsicLowering::AddPrototypes(Module &M) {
00096   LLVMContext &Context = M.getContext();
00097   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
00098     if (I->isDeclaration() && !I->use_empty())
00099       switch (I->getIntrinsicID()) {
00100       default: break;
00101       case Intrinsic::setjmp:
00102         EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
00103                              Type::getInt32Ty(M.getContext()));
00104         break;
00105       case Intrinsic::longjmp:
00106         EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
00107                              Type::getVoidTy(M.getContext()));
00108         break;
00109       case Intrinsic::siglongjmp:
00110         EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
00111                              Type::getVoidTy(M.getContext()));
00112         break;
00113       case Intrinsic::memcpy:
00114         M.getOrInsertFunction("memcpy",
00115           Type::getInt8PtrTy(Context),
00116                               Type::getInt8PtrTy(Context), 
00117                               Type::getInt8PtrTy(Context), 
00118                               DL.getIntPtrType(Context), nullptr);
00119         break;
00120       case Intrinsic::memmove:
00121         M.getOrInsertFunction("memmove",
00122           Type::getInt8PtrTy(Context),
00123                               Type::getInt8PtrTy(Context), 
00124                               Type::getInt8PtrTy(Context), 
00125                               DL.getIntPtrType(Context), nullptr);
00126         break;
00127       case Intrinsic::memset:
00128         M.getOrInsertFunction("memset",
00129           Type::getInt8PtrTy(Context),
00130                               Type::getInt8PtrTy(Context), 
00131                               Type::getInt32Ty(M.getContext()), 
00132                               DL.getIntPtrType(Context), nullptr);
00133         break;
00134       case Intrinsic::sqrt:
00135         EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
00136         break;
00137       case Intrinsic::sin:
00138         EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
00139         break;
00140       case Intrinsic::cos:
00141         EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
00142         break;
00143       case Intrinsic::pow:
00144         EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
00145         break;
00146       case Intrinsic::log:
00147         EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
00148         break;
00149       case Intrinsic::log2:
00150         EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
00151         break;
00152       case Intrinsic::log10:
00153         EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
00154         break;
00155       case Intrinsic::exp:
00156         EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
00157         break;
00158       case Intrinsic::exp2:
00159         EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
00160         break;
00161       }
00162 }
00163 
00164 /// LowerBSWAP - Emit the code to lower bswap of V before the specified
00165 /// instruction IP.
00166 static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
00167   assert(V->getType()->isIntegerTy() && "Can't bswap a non-integer type!");
00168 
00169   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
00170   
00171   IRBuilder<> Builder(IP->getParent(), IP);
00172 
00173   switch(BitSize) {
00174   default: llvm_unreachable("Unhandled type size of value to byteswap!");
00175   case 16: {
00176     Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
00177                                     "bswap.2");
00178     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
00179                                      "bswap.1");
00180     V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
00181     break;
00182   }
00183   case 32: {
00184     Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
00185                                     "bswap.4");
00186     Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
00187                                     "bswap.3");
00188     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
00189                                      "bswap.2");
00190     Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
00191                                      "bswap.1");
00192     Tmp3 = Builder.CreateAnd(Tmp3,
00193                          ConstantInt::get(Type::getInt32Ty(Context), 0xFF0000),
00194                              "bswap.and3");
00195     Tmp2 = Builder.CreateAnd(Tmp2,
00196                            ConstantInt::get(Type::getInt32Ty(Context), 0xFF00),
00197                              "bswap.and2");
00198     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
00199     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
00200     V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
00201     break;
00202   }
00203   case 64: {
00204     Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
00205                                     "bswap.8");
00206     Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
00207                                     "bswap.7");
00208     Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
00209                                     "bswap.6");
00210     Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
00211                                     "bswap.5");
00212     Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
00213                                      "bswap.4");
00214     Value* Tmp3 = Builder.CreateLShr(V, 
00215                                      ConstantInt::get(V->getType(), 24),
00216                                      "bswap.3");
00217     Value* Tmp2 = Builder.CreateLShr(V, 
00218                                      ConstantInt::get(V->getType(), 40),
00219                                      "bswap.2");
00220     Value* Tmp1 = Builder.CreateLShr(V, 
00221                                      ConstantInt::get(V->getType(), 56),
00222                                      "bswap.1");
00223     Tmp7 = Builder.CreateAnd(Tmp7,
00224                              ConstantInt::get(Type::getInt64Ty(Context),
00225                                               0xFF000000000000ULL),
00226                              "bswap.and7");
00227     Tmp6 = Builder.CreateAnd(Tmp6,
00228                              ConstantInt::get(Type::getInt64Ty(Context),
00229                                               0xFF0000000000ULL),
00230                              "bswap.and6");
00231     Tmp5 = Builder.CreateAnd(Tmp5,
00232                         ConstantInt::get(Type::getInt64Ty(Context),
00233                              0xFF00000000ULL),
00234                              "bswap.and5");
00235     Tmp4 = Builder.CreateAnd(Tmp4,
00236                         ConstantInt::get(Type::getInt64Ty(Context),
00237                              0xFF000000ULL),
00238                              "bswap.and4");
00239     Tmp3 = Builder.CreateAnd(Tmp3,
00240                              ConstantInt::get(Type::getInt64Ty(Context),
00241                              0xFF0000ULL),
00242                              "bswap.and3");
00243     Tmp2 = Builder.CreateAnd(Tmp2,
00244                              ConstantInt::get(Type::getInt64Ty(Context),
00245                              0xFF00ULL),
00246                              "bswap.and2");
00247     Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
00248     Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
00249     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
00250     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
00251     Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
00252     Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
00253     V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
00254     break;
00255   }
00256   }
00257   return V;
00258 }
00259 
00260 /// LowerCTPOP - Emit the code to lower ctpop of V before the specified
00261 /// instruction IP.
00262 static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
00263   assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");
00264 
00265   static const uint64_t MaskValues[6] = {
00266     0x5555555555555555ULL, 0x3333333333333333ULL,
00267     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
00268     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
00269   };
00270 
00271   IRBuilder<> Builder(IP->getParent(), IP);
00272 
00273   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
00274   unsigned WordSize = (BitSize + 63) / 64;
00275   Value *Count = ConstantInt::get(V->getType(), 0);
00276 
00277   for (unsigned n = 0; n < WordSize; ++n) {
00278     Value *PartValue = V;
00279     for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize); 
00280          i <<= 1, ++ct) {
00281       Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
00282       Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
00283       Value *VShift = Builder.CreateLShr(PartValue,
00284                                         ConstantInt::get(V->getType(), i),
00285                                          "ctpop.sh");
00286       Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
00287       PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
00288     }
00289     Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
00290     if (BitSize > 64) {
00291       V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
00292                              "ctpop.part.sh");
00293       BitSize -= 64;
00294     }
00295   }
00296 
00297   return Count;
00298 }
00299 
00300 /// LowerCTLZ - Emit the code to lower ctlz of V before the specified
00301 /// instruction IP.
00302 static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
00303 
00304   IRBuilder<> Builder(IP->getParent(), IP);
00305 
00306   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
00307   for (unsigned i = 1; i < BitSize; i <<= 1) {
00308     Value *ShVal = ConstantInt::get(V->getType(), i);
00309     ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
00310     V = Builder.CreateOr(V, ShVal, "ctlz.step");
00311   }
00312 
00313   V = Builder.CreateNot(V);
00314   return LowerCTPOP(Context, V, IP);
00315 }
00316 
00317 static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
00318                                        const char *Dname,
00319                                        const char *LDname) {
00320   CallSite CS(CI);
00321   switch (CI->getArgOperand(0)->getType()->getTypeID()) {
00322   default: llvm_unreachable("Invalid type in intrinsic");
00323   case Type::FloatTyID:
00324     ReplaceCallWith(Fname, CI, CS.arg_begin(), CS.arg_end(),
00325                   Type::getFloatTy(CI->getContext()));
00326     break;
00327   case Type::DoubleTyID:
00328     ReplaceCallWith(Dname, CI, CS.arg_begin(), CS.arg_end(),
00329                   Type::getDoubleTy(CI->getContext()));
00330     break;
00331   case Type::X86_FP80TyID:
00332   case Type::FP128TyID:
00333   case Type::PPC_FP128TyID:
00334     ReplaceCallWith(LDname, CI, CS.arg_begin(), CS.arg_end(),
00335                   CI->getArgOperand(0)->getType());
00336     break;
00337   }
00338 }
00339 
00340 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
00341   IRBuilder<> Builder(CI->getParent(), CI);
00342   LLVMContext &Context = CI->getContext();
00343 
00344   const Function *Callee = CI->getCalledFunction();
00345   assert(Callee && "Cannot lower an indirect call!");
00346 
00347   CallSite CS(CI);
00348   switch (Callee->getIntrinsicID()) {
00349   case Intrinsic::not_intrinsic:
00350     report_fatal_error("Cannot lower a call to a non-intrinsic function '"+
00351                       Callee->getName() + "'!");
00352   default:
00353     report_fatal_error("Code generator does not support intrinsic function '"+
00354                       Callee->getName()+"'!");
00355 
00356   case Intrinsic::expect: {
00357     // Just replace __builtin_expect(exp, c) with EXP.
00358     Value *V = CI->getArgOperand(0);
00359     CI->replaceAllUsesWith(V);
00360     break;
00361   }
00362 
00363     // The setjmp/longjmp intrinsics should only exist in the code if it was
00364     // never optimized (ie, right out of the CFE), or if it has been hacked on
00365     // by the lowerinvoke pass.  In both cases, the right thing to do is to
00366     // convert the call to an explicit setjmp or longjmp call.
00367   case Intrinsic::setjmp: {
00368     Value *V = ReplaceCallWith("setjmp", CI, CS.arg_begin(), CS.arg_end(),
00369                                Type::getInt32Ty(Context));
00370     if (!CI->getType()->isVoidTy())
00371       CI->replaceAllUsesWith(V);
00372     break;
00373   }
00374   case Intrinsic::sigsetjmp:
00375      if (!CI->getType()->isVoidTy())
00376        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
00377      break;
00378 
00379   case Intrinsic::longjmp: {
00380     ReplaceCallWith("longjmp", CI, CS.arg_begin(), CS.arg_end(),
00381                     Type::getVoidTy(Context));
00382     break;
00383   }
00384 
00385   case Intrinsic::siglongjmp: {
00386     // Insert the call to abort
00387     ReplaceCallWith("abort", CI, CS.arg_end(), CS.arg_end(), 
00388                     Type::getVoidTy(Context));
00389     break;
00390   }
00391   case Intrinsic::ctpop:
00392     CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI));
00393     break;
00394 
00395   case Intrinsic::bswap:
00396     CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI));
00397     break;
00398     
00399   case Intrinsic::ctlz:
00400     CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI));
00401     break;
00402 
00403   case Intrinsic::cttz: {
00404     // cttz(x) -> ctpop(~X & (X-1))
00405     Value *Src = CI->getArgOperand(0);
00406     Value *NotSrc = Builder.CreateNot(Src);
00407     NotSrc->setName(Src->getName() + ".not");
00408     Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
00409     SrcM1 = Builder.CreateSub(Src, SrcM1);
00410     Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
00411     CI->replaceAllUsesWith(Src);
00412     break;
00413   }
00414 
00415   case Intrinsic::stacksave:
00416   case Intrinsic::stackrestore: {
00417     if (!Warned)
00418       errs() << "WARNING: this target does not support the llvm.stack"
00419              << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
00420                "save" : "restore") << " intrinsic.\n";
00421     Warned = true;
00422     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
00423       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
00424     break;
00425   }
00426     
00427   case Intrinsic::returnaddress:
00428   case Intrinsic::frameaddress:
00429     errs() << "WARNING: this target does not support the llvm."
00430            << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
00431              "return" : "frame") << "address intrinsic.\n";
00432     CI->replaceAllUsesWith(ConstantPointerNull::get(
00433                                             cast<PointerType>(CI->getType())));
00434     break;
00435 
00436   case Intrinsic::prefetch:
00437     break;    // Simply strip out prefetches on unsupported architectures
00438 
00439   case Intrinsic::pcmarker:
00440     break;    // Simply strip out pcmarker on unsupported architectures
00441   case Intrinsic::readcyclecounter: {
00442     errs() << "WARNING: this target does not support the llvm.readcyclecoun"
00443            << "ter intrinsic.  It is being lowered to a constant 0\n";
00444     CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
00445     break;
00446   }
00447 
00448   case Intrinsic::dbg_declare:
00449     break;    // Simply strip out debugging intrinsics
00450 
00451   case Intrinsic::eh_typeid_for:
00452     // Return something different to eh_selector.
00453     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
00454     break;
00455 
00456   case Intrinsic::annotation:
00457   case Intrinsic::ptr_annotation:
00458     // Just drop the annotation, but forward the value
00459     CI->replaceAllUsesWith(CI->getOperand(0));
00460     break;
00461 
00462   case Intrinsic::assume:
00463   case Intrinsic::var_annotation:
00464     break;   // Strip out these intrinsics
00465  
00466   case Intrinsic::memcpy: {
00467     Type *IntPtr = DL.getIntPtrType(Context);
00468     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
00469                                         /* isSigned */ false);
00470     Value *Ops[3];
00471     Ops[0] = CI->getArgOperand(0);
00472     Ops[1] = CI->getArgOperand(1);
00473     Ops[2] = Size;
00474     ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
00475     break;
00476   }
00477   case Intrinsic::memmove: {
00478     Type *IntPtr = DL.getIntPtrType(Context);
00479     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
00480                                         /* isSigned */ false);
00481     Value *Ops[3];
00482     Ops[0] = CI->getArgOperand(0);
00483     Ops[1] = CI->getArgOperand(1);
00484     Ops[2] = Size;
00485     ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
00486     break;
00487   }
00488   case Intrinsic::memset: {
00489     Value *Op0 = CI->getArgOperand(0);
00490     Type *IntPtr = DL.getIntPtrType(Op0->getType());
00491     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
00492                                         /* isSigned */ false);
00493     Value *Ops[3];
00494     Ops[0] = Op0;
00495     // Extend the amount to i32.
00496     Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1),
00497                                    Type::getInt32Ty(Context),
00498                                    /* isSigned */ false);
00499     Ops[2] = Size;
00500     ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
00501     break;
00502   }
00503   case Intrinsic::sqrt: {
00504     ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
00505     break;
00506   }
00507   case Intrinsic::log: {
00508     ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
00509     break;
00510   }
00511   case Intrinsic::log2: {
00512     ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
00513     break;
00514   }
00515   case Intrinsic::log10: {
00516     ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
00517     break;
00518   }
00519   case Intrinsic::exp: {
00520     ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
00521     break;
00522   }
00523   case Intrinsic::exp2: {
00524     ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
00525     break;
00526   }
00527   case Intrinsic::pow: {
00528     ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
00529     break;
00530   }
00531   case Intrinsic::sin: {
00532     ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl");
00533     break;
00534   }
00535   case Intrinsic::cos: {
00536     ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl");
00537     break;
00538   }
00539   case Intrinsic::ceil: {
00540     ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill");
00541     break;
00542   }
00543   case Intrinsic::flt_rounds:
00544      // Lower to "round to the nearest"
00545      if (!CI->getType()->isVoidTy())
00546        CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
00547      break;
00548   case Intrinsic::invariant_start:
00549   case Intrinsic::lifetime_start:
00550     // Discard region information.
00551     CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
00552     break;
00553   case Intrinsic::invariant_end:
00554   case Intrinsic::lifetime_end:
00555     // Discard region information.
00556     break;
00557   }
00558 
00559   assert(CI->use_empty() &&
00560          "Lowering should have eliminated any uses of the intrinsic call!");
00561   CI->eraseFromParent();
00562 }
00563 
00564 bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) {
00565   // Verify this is a simple bswap.
00566   if (CI->getNumArgOperands() != 1 ||
00567       CI->getType() != CI->getArgOperand(0)->getType() ||
00568       !CI->getType()->isIntegerTy())
00569     return false;
00570 
00571   IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
00572   if (!Ty)
00573     return false;
00574 
00575   // Okay, we can do this xform, do so now.
00576   Module *M = CI->getParent()->getParent()->getParent();
00577   Constant *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty);
00578 
00579   Value *Op = CI->getArgOperand(0);
00580   Op = CallInst::Create(Int, Op, CI->getName(), CI);
00581 
00582   CI->replaceAllUsesWith(Op);
00583   CI->eraseFromParent();
00584   return true;
00585 }