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      1 //===-- AutoUpgrade.cpp - Implement auto-upgrade helper functions ---------===//
      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 auto-upgrade helper functions
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/IR/AutoUpgrade.h"
     15 #include "llvm/IR/CFG.h"
     16 #include "llvm/IR/CallSite.h"
     17 #include "llvm/IR/Constants.h"
     18 #include "llvm/IR/DebugInfo.h"
     19 #include "llvm/IR/DiagnosticInfo.h"
     20 #include "llvm/IR/Function.h"
     21 #include "llvm/IR/IRBuilder.h"
     22 #include "llvm/IR/Instruction.h"
     23 #include "llvm/IR/IntrinsicInst.h"
     24 #include "llvm/IR/LLVMContext.h"
     25 #include "llvm/IR/Module.h"
     26 #include "llvm/Support/ErrorHandling.h"
     27 #include <cstring>
     28 using namespace llvm;
     29 
     30 // Upgrade the declarations of the SSE4.1 functions whose arguments have
     31 // changed their type from v4f32 to v2i64.
     32 static bool UpgradeSSE41Function(Function* F, Intrinsic::ID IID,
     33                                  Function *&NewFn) {
     34   // Check whether this is an old version of the function, which received
     35   // v4f32 arguments.
     36   Type *Arg0Type = F->getFunctionType()->getParamType(0);
     37   if (Arg0Type != VectorType::get(Type::getFloatTy(F->getContext()), 4))
     38     return false;
     39 
     40   // Yes, it's old, replace it with new version.
     41   F->setName(F->getName() + ".old");
     42   NewFn = Intrinsic::getDeclaration(F->getParent(), IID);
     43   return true;
     44 }
     45 
     46 static bool UpgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
     47   assert(F && "Illegal to upgrade a non-existent Function.");
     48 
     49   // Quickly eliminate it, if it's not a candidate.
     50   StringRef Name = F->getName();
     51   if (Name.size() <= 8 || !Name.startswith("llvm."))
     52     return false;
     53   Name = Name.substr(5); // Strip off "llvm."
     54 
     55   switch (Name[0]) {
     56   default: break;
     57   case 'a': {
     58     if (Name.startswith("arm.neon.vclz")) {
     59       Type* args[2] = {
     60         F->arg_begin()->getType(),
     61         Type::getInt1Ty(F->getContext())
     62       };
     63       // Can't use Intrinsic::getDeclaration here as it adds a ".i1" to
     64       // the end of the name. Change name from llvm.arm.neon.vclz.* to
     65       //  llvm.ctlz.*
     66       FunctionType* fType = FunctionType::get(F->getReturnType(), args, false);
     67       NewFn = Function::Create(fType, F->getLinkage(),
     68                                "llvm.ctlz." + Name.substr(14), F->getParent());
     69       return true;
     70     }
     71     if (Name.startswith("arm.neon.vcnt")) {
     72       NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctpop,
     73                                         F->arg_begin()->getType());
     74       return true;
     75     }
     76     break;
     77   }
     78   case 'c': {
     79     if (Name.startswith("ctlz.") && F->arg_size() == 1) {
     80       F->setName(Name + ".old");
     81       NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz,
     82                                         F->arg_begin()->getType());
     83       return true;
     84     }
     85     if (Name.startswith("cttz.") && F->arg_size() == 1) {
     86       F->setName(Name + ".old");
     87       NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::cttz,
     88                                         F->arg_begin()->getType());
     89       return true;
     90     }
     91     break;
     92   }
     93   case 'o':
     94     // We only need to change the name to match the mangling including the
     95     // address space.
     96     if (F->arg_size() == 2 && Name.startswith("objectsize.")) {
     97       Type *Tys[2] = { F->getReturnType(), F->arg_begin()->getType() };
     98       if (F->getName() != Intrinsic::getName(Intrinsic::objectsize, Tys)) {
     99         F->setName(Name + ".old");
    100         NewFn = Intrinsic::getDeclaration(F->getParent(),
    101                                           Intrinsic::objectsize, Tys);
    102         return true;
    103       }
    104     }
    105     break;
    106 
    107   case 'x': {
    108     if (Name.startswith("x86.sse2.pcmpeq.") ||
    109         Name.startswith("x86.sse2.pcmpgt.") ||
    110         Name.startswith("x86.avx2.pcmpeq.") ||
    111         Name.startswith("x86.avx2.pcmpgt.") ||
    112         Name.startswith("x86.avx.vpermil.") ||
    113         Name == "x86.avx.movnt.dq.256" ||
    114         Name == "x86.avx.movnt.pd.256" ||
    115         Name == "x86.avx.movnt.ps.256" ||
    116         Name == "x86.sse42.crc32.64.8" ||
    117         Name == "x86.avx.vbroadcast.ss" ||
    118         Name == "x86.avx.vbroadcast.ss.256" ||
    119         Name == "x86.avx.vbroadcast.sd.256" ||
    120         (Name.startswith("x86.xop.vpcom") && F->arg_size() == 2)) {
    121       NewFn = nullptr;
    122       return true;
    123     }
    124     // SSE4.1 ptest functions may have an old signature.
    125     if (Name.startswith("x86.sse41.ptest")) {
    126       if (Name == "x86.sse41.ptestc")
    127         return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestc, NewFn);
    128       if (Name == "x86.sse41.ptestz")
    129         return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestz, NewFn);
    130       if (Name == "x86.sse41.ptestnzc")
    131         return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestnzc, NewFn);
    132     }
    133     // frcz.ss/sd may need to have an argument dropped
    134     if (Name.startswith("x86.xop.vfrcz.ss") && F->arg_size() == 2) {
    135       F->setName(Name + ".old");
    136       NewFn = Intrinsic::getDeclaration(F->getParent(),
    137                                         Intrinsic::x86_xop_vfrcz_ss);
    138       return true;
    139     }
    140     if (Name.startswith("x86.xop.vfrcz.sd") && F->arg_size() == 2) {
    141       F->setName(Name + ".old");
    142       NewFn = Intrinsic::getDeclaration(F->getParent(),
    143                                         Intrinsic::x86_xop_vfrcz_sd);
    144       return true;
    145     }
    146     // Fix the FMA4 intrinsics to remove the 4
    147     if (Name.startswith("x86.fma4.")) {
    148       F->setName("llvm.x86.fma" + Name.substr(8));
    149       NewFn = F;
    150       return true;
    151     }
    152     break;
    153   }
    154   }
    155 
    156   //  This may not belong here. This function is effectively being overloaded
    157   //  to both detect an intrinsic which needs upgrading, and to provide the
    158   //  upgraded form of the intrinsic. We should perhaps have two separate
    159   //  functions for this.
    160   return false;
    161 }
    162 
    163 bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn) {
    164   NewFn = nullptr;
    165   bool Upgraded = UpgradeIntrinsicFunction1(F, NewFn);
    166 
    167   // Upgrade intrinsic attributes.  This does not change the function.
    168   if (NewFn)
    169     F = NewFn;
    170   if (unsigned id = F->getIntrinsicID())
    171     F->setAttributes(Intrinsic::getAttributes(F->getContext(),
    172                                               (Intrinsic::ID)id));
    173   return Upgraded;
    174 }
    175 
    176 static bool UpgradeGlobalStructors(GlobalVariable *GV) {
    177   ArrayType *ATy = dyn_cast<ArrayType>(GV->getType()->getElementType());
    178   StructType *OldTy =
    179       ATy ? dyn_cast<StructType>(ATy->getElementType()) : nullptr;
    180 
    181   // Only upgrade an array of a two field struct with the appropriate field
    182   // types.
    183   if (!OldTy || OldTy->getNumElements() != 2)
    184     return false;
    185 
    186   // Get the upgraded 3 element type.
    187   PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
    188   Type *Tys[3] = {
    189     OldTy->getElementType(0),
    190     OldTy->getElementType(1),
    191     VoidPtrTy
    192   };
    193   StructType *NewTy =
    194       StructType::get(GV->getContext(), Tys, /*isPacked=*/false);
    195 
    196   // Build new constants with a null third field filled in.
    197   Constant *OldInitC = GV->getInitializer();
    198   ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
    199   if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
    200     return false;
    201   std::vector<Constant *> Initializers;
    202   if (OldInit) {
    203     for (Use &U : OldInit->operands()) {
    204       ConstantStruct *Init = cast<ConstantStruct>(&U);
    205       Constant *NewInit =
    206         ConstantStruct::get(NewTy, Init->getOperand(0), Init->getOperand(1),
    207                             Constant::getNullValue(VoidPtrTy), nullptr);
    208       Initializers.push_back(NewInit);
    209     }
    210   }
    211   assert(Initializers.size() == ATy->getNumElements());
    212 
    213   // Replace the old GV with a new one.
    214   ATy = ArrayType::get(NewTy, Initializers.size());
    215   Constant *NewInit = ConstantArray::get(ATy, Initializers);
    216   GlobalVariable *NewGV = new GlobalVariable(
    217       *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
    218       GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
    219       GV->isExternallyInitialized());
    220   NewGV->copyAttributesFrom(GV);
    221   NewGV->takeName(GV);
    222   assert(GV->use_empty() && "program cannot use initializer list");
    223   GV->eraseFromParent();
    224   return true;
    225 }
    226 
    227 bool llvm::UpgradeGlobalVariable(GlobalVariable *GV) {
    228   if (GV->getName() == "llvm.global_ctors" ||
    229       GV->getName() == "llvm.global_dtors")
    230     return UpgradeGlobalStructors(GV);
    231 
    232   // Nothing to do yet.
    233   return false;
    234 }
    235 
    236 // UpgradeIntrinsicCall - Upgrade a call to an old intrinsic to be a call the
    237 // upgraded intrinsic. All argument and return casting must be provided in
    238 // order to seamlessly integrate with existing context.
    239 void llvm::UpgradeIntrinsicCall(CallInst *CI, Function *NewFn) {
    240   Function *F = CI->getCalledFunction();
    241   LLVMContext &C = CI->getContext();
    242   IRBuilder<> Builder(C);
    243   Builder.SetInsertPoint(CI->getParent(), CI);
    244 
    245   assert(F && "Intrinsic call is not direct?");
    246 
    247   if (!NewFn) {
    248     // Get the Function's name.
    249     StringRef Name = F->getName();
    250 
    251     Value *Rep;
    252     // Upgrade packed integer vector compares intrinsics to compare instructions
    253     if (Name.startswith("llvm.x86.sse2.pcmpeq.") ||
    254         Name.startswith("llvm.x86.avx2.pcmpeq.")) {
    255       Rep = Builder.CreateICmpEQ(CI->getArgOperand(0), CI->getArgOperand(1),
    256                                  "pcmpeq");
    257       // need to sign extend since icmp returns vector of i1
    258       Rep = Builder.CreateSExt(Rep, CI->getType(), "");
    259     } else if (Name.startswith("llvm.x86.sse2.pcmpgt.") ||
    260                Name.startswith("llvm.x86.avx2.pcmpgt.")) {
    261       Rep = Builder.CreateICmpSGT(CI->getArgOperand(0), CI->getArgOperand(1),
    262                                   "pcmpgt");
    263       // need to sign extend since icmp returns vector of i1
    264       Rep = Builder.CreateSExt(Rep, CI->getType(), "");
    265     } else if (Name == "llvm.x86.avx.movnt.dq.256" ||
    266                Name == "llvm.x86.avx.movnt.ps.256" ||
    267                Name == "llvm.x86.avx.movnt.pd.256") {
    268       IRBuilder<> Builder(C);
    269       Builder.SetInsertPoint(CI->getParent(), CI);
    270 
    271       Module *M = F->getParent();
    272       SmallVector<Value *, 1> Elts;
    273       Elts.push_back(ConstantInt::get(Type::getInt32Ty(C), 1));
    274       MDNode *Node = MDNode::get(C, Elts);
    275 
    276       Value *Arg0 = CI->getArgOperand(0);
    277       Value *Arg1 = CI->getArgOperand(1);
    278 
    279       // Convert the type of the pointer to a pointer to the stored type.
    280       Value *BC = Builder.CreateBitCast(Arg0,
    281                                         PointerType::getUnqual(Arg1->getType()),
    282                                         "cast");
    283       StoreInst *SI = Builder.CreateStore(Arg1, BC);
    284       SI->setMetadata(M->getMDKindID("nontemporal"), Node);
    285       SI->setAlignment(16);
    286 
    287       // Remove intrinsic.
    288       CI->eraseFromParent();
    289       return;
    290     } else if (Name.startswith("llvm.x86.xop.vpcom")) {
    291       Intrinsic::ID intID;
    292       if (Name.endswith("ub"))
    293         intID = Intrinsic::x86_xop_vpcomub;
    294       else if (Name.endswith("uw"))
    295         intID = Intrinsic::x86_xop_vpcomuw;
    296       else if (Name.endswith("ud"))
    297         intID = Intrinsic::x86_xop_vpcomud;
    298       else if (Name.endswith("uq"))
    299         intID = Intrinsic::x86_xop_vpcomuq;
    300       else if (Name.endswith("b"))
    301         intID = Intrinsic::x86_xop_vpcomb;
    302       else if (Name.endswith("w"))
    303         intID = Intrinsic::x86_xop_vpcomw;
    304       else if (Name.endswith("d"))
    305         intID = Intrinsic::x86_xop_vpcomd;
    306       else if (Name.endswith("q"))
    307         intID = Intrinsic::x86_xop_vpcomq;
    308       else
    309         llvm_unreachable("Unknown suffix");
    310 
    311       Name = Name.substr(18); // strip off "llvm.x86.xop.vpcom"
    312       unsigned Imm;
    313       if (Name.startswith("lt"))
    314         Imm = 0;
    315       else if (Name.startswith("le"))
    316         Imm = 1;
    317       else if (Name.startswith("gt"))
    318         Imm = 2;
    319       else if (Name.startswith("ge"))
    320         Imm = 3;
    321       else if (Name.startswith("eq"))
    322         Imm = 4;
    323       else if (Name.startswith("ne"))
    324         Imm = 5;
    325       else if (Name.startswith("true"))
    326         Imm = 6;
    327       else if (Name.startswith("false"))
    328         Imm = 7;
    329       else
    330         llvm_unreachable("Unknown condition");
    331 
    332       Function *VPCOM = Intrinsic::getDeclaration(F->getParent(), intID);
    333       Rep = Builder.CreateCall3(VPCOM, CI->getArgOperand(0),
    334                                 CI->getArgOperand(1), Builder.getInt8(Imm));
    335     } else if (Name == "llvm.x86.sse42.crc32.64.8") {
    336       Function *CRC32 = Intrinsic::getDeclaration(F->getParent(),
    337                                                Intrinsic::x86_sse42_crc32_32_8);
    338       Value *Trunc0 = Builder.CreateTrunc(CI->getArgOperand(0), Type::getInt32Ty(C));
    339       Rep = Builder.CreateCall2(CRC32, Trunc0, CI->getArgOperand(1));
    340       Rep = Builder.CreateZExt(Rep, CI->getType(), "");
    341     } else if (Name.startswith("llvm.x86.avx.vbroadcast")) {
    342       // Replace broadcasts with a series of insertelements.
    343       Type *VecTy = CI->getType();
    344       Type *EltTy = VecTy->getVectorElementType();
    345       unsigned EltNum = VecTy->getVectorNumElements();
    346       Value *Cast = Builder.CreateBitCast(CI->getArgOperand(0),
    347                                           EltTy->getPointerTo());
    348       Value *Load = Builder.CreateLoad(Cast);
    349       Type *I32Ty = Type::getInt32Ty(C);
    350       Rep = UndefValue::get(VecTy);
    351       for (unsigned I = 0; I < EltNum; ++I)
    352         Rep = Builder.CreateInsertElement(Rep, Load,
    353                                           ConstantInt::get(I32Ty, I));
    354     } else {
    355       bool PD128 = false, PD256 = false, PS128 = false, PS256 = false;
    356       if (Name == "llvm.x86.avx.vpermil.pd.256")
    357         PD256 = true;
    358       else if (Name == "llvm.x86.avx.vpermil.pd")
    359         PD128 = true;
    360       else if (Name == "llvm.x86.avx.vpermil.ps.256")
    361         PS256 = true;
    362       else if (Name == "llvm.x86.avx.vpermil.ps")
    363         PS128 = true;
    364 
    365       if (PD256 || PD128 || PS256 || PS128) {
    366         Value *Op0 = CI->getArgOperand(0);
    367         unsigned Imm = cast<ConstantInt>(CI->getArgOperand(1))->getZExtValue();
    368         SmallVector<Constant*, 8> Idxs;
    369 
    370         if (PD128)
    371           for (unsigned i = 0; i != 2; ++i)
    372             Idxs.push_back(Builder.getInt32((Imm >> i) & 0x1));
    373         else if (PD256)
    374           for (unsigned l = 0; l != 4; l+=2)
    375             for (unsigned i = 0; i != 2; ++i)
    376               Idxs.push_back(Builder.getInt32(((Imm >> (l+i)) & 0x1) + l));
    377         else if (PS128)
    378           for (unsigned i = 0; i != 4; ++i)
    379             Idxs.push_back(Builder.getInt32((Imm >> (2 * i)) & 0x3));
    380         else if (PS256)
    381           for (unsigned l = 0; l != 8; l+=4)
    382             for (unsigned i = 0; i != 4; ++i)
    383               Idxs.push_back(Builder.getInt32(((Imm >> (2 * i)) & 0x3) + l));
    384         else
    385           llvm_unreachable("Unexpected function");
    386 
    387         Rep = Builder.CreateShuffleVector(Op0, Op0, ConstantVector::get(Idxs));
    388       } else {
    389         llvm_unreachable("Unknown function for CallInst upgrade.");
    390       }
    391     }
    392 
    393     CI->replaceAllUsesWith(Rep);
    394     CI->eraseFromParent();
    395     return;
    396   }
    397 
    398   std::string Name = CI->getName().str();
    399   CI->setName(Name + ".old");
    400 
    401   switch (NewFn->getIntrinsicID()) {
    402   default:
    403     llvm_unreachable("Unknown function for CallInst upgrade.");
    404 
    405   case Intrinsic::ctlz:
    406   case Intrinsic::cttz:
    407     assert(CI->getNumArgOperands() == 1 &&
    408            "Mismatch between function args and call args");
    409     CI->replaceAllUsesWith(Builder.CreateCall2(NewFn, CI->getArgOperand(0),
    410                                                Builder.getFalse(), Name));
    411     CI->eraseFromParent();
    412     return;
    413 
    414   case Intrinsic::objectsize:
    415     CI->replaceAllUsesWith(Builder.CreateCall2(NewFn,
    416                                                CI->getArgOperand(0),
    417                                                CI->getArgOperand(1),
    418                                                Name));
    419     CI->eraseFromParent();
    420     return;
    421 
    422   case Intrinsic::arm_neon_vclz: {
    423     // Change name from llvm.arm.neon.vclz.* to llvm.ctlz.*
    424     CI->replaceAllUsesWith(Builder.CreateCall2(NewFn, CI->getArgOperand(0),
    425                                                Builder.getFalse(),
    426                                                "llvm.ctlz." + Name.substr(14)));
    427     CI->eraseFromParent();
    428     return;
    429   }
    430   case Intrinsic::ctpop: {
    431     CI->replaceAllUsesWith(Builder.CreateCall(NewFn, CI->getArgOperand(0)));
    432     CI->eraseFromParent();
    433     return;
    434   }
    435 
    436   case Intrinsic::x86_xop_vfrcz_ss:
    437   case Intrinsic::x86_xop_vfrcz_sd:
    438     CI->replaceAllUsesWith(Builder.CreateCall(NewFn, CI->getArgOperand(1),
    439                                               Name));
    440     CI->eraseFromParent();
    441     return;
    442 
    443   case Intrinsic::x86_sse41_ptestc:
    444   case Intrinsic::x86_sse41_ptestz:
    445   case Intrinsic::x86_sse41_ptestnzc: {
    446     // The arguments for these intrinsics used to be v4f32, and changed
    447     // to v2i64. This is purely a nop, since those are bitwise intrinsics.
    448     // So, the only thing required is a bitcast for both arguments.
    449     // First, check the arguments have the old type.
    450     Value *Arg0 = CI->getArgOperand(0);
    451     if (Arg0->getType() != VectorType::get(Type::getFloatTy(C), 4))
    452       return;
    453 
    454     // Old intrinsic, add bitcasts
    455     Value *Arg1 = CI->getArgOperand(1);
    456 
    457     Value *BC0 =
    458       Builder.CreateBitCast(Arg0,
    459                             VectorType::get(Type::getInt64Ty(C), 2),
    460                             "cast");
    461     Value *BC1 =
    462       Builder.CreateBitCast(Arg1,
    463                             VectorType::get(Type::getInt64Ty(C), 2),
    464                             "cast");
    465 
    466     CallInst* NewCall = Builder.CreateCall2(NewFn, BC0, BC1, Name);
    467     CI->replaceAllUsesWith(NewCall);
    468     CI->eraseFromParent();
    469     return;
    470   }
    471   }
    472 }
    473 
    474 // This tests each Function to determine if it needs upgrading. When we find
    475 // one we are interested in, we then upgrade all calls to reflect the new
    476 // function.
    477 void llvm::UpgradeCallsToIntrinsic(Function* F) {
    478   assert(F && "Illegal attempt to upgrade a non-existent intrinsic.");
    479 
    480   // Upgrade the function and check if it is a totaly new function.
    481   Function *NewFn;
    482   if (UpgradeIntrinsicFunction(F, NewFn)) {
    483     if (NewFn != F) {
    484       // Replace all uses to the old function with the new one if necessary.
    485       for (Value::user_iterator UI = F->user_begin(), UE = F->user_end();
    486            UI != UE; ) {
    487         if (CallInst *CI = dyn_cast<CallInst>(*UI++))
    488           UpgradeIntrinsicCall(CI, NewFn);
    489       }
    490       // Remove old function, no longer used, from the module.
    491       F->eraseFromParent();
    492     }
    493   }
    494 }
    495 
    496 void llvm::UpgradeInstWithTBAATag(Instruction *I) {
    497   MDNode *MD = I->getMetadata(LLVMContext::MD_tbaa);
    498   assert(MD && "UpgradeInstWithTBAATag should have a TBAA tag");
    499   // Check if the tag uses struct-path aware TBAA format.
    500   if (isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3)
    501     return;
    502 
    503   if (MD->getNumOperands() == 3) {
    504     Value *Elts[] = {
    505       MD->getOperand(0),
    506       MD->getOperand(1)
    507     };
    508     MDNode *ScalarType = MDNode::get(I->getContext(), Elts);
    509     // Create a MDNode <ScalarType, ScalarType, offset 0, const>
    510     Value *Elts2[] = {
    511       ScalarType, ScalarType,
    512       Constant::getNullValue(Type::getInt64Ty(I->getContext())),
    513       MD->getOperand(2)
    514     };
    515     I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts2));
    516   } else {
    517     // Create a MDNode <MD, MD, offset 0>
    518     Value *Elts[] = {MD, MD,
    519       Constant::getNullValue(Type::getInt64Ty(I->getContext()))};
    520     I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts));
    521   }
    522 }
    523 
    524 Instruction *llvm::UpgradeBitCastInst(unsigned Opc, Value *V, Type *DestTy,
    525                                       Instruction *&Temp) {
    526   if (Opc != Instruction::BitCast)
    527     return nullptr;
    528 
    529   Temp = nullptr;
    530   Type *SrcTy = V->getType();
    531   if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
    532       SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
    533     LLVMContext &Context = V->getContext();
    534 
    535     // We have no information about target data layout, so we assume that
    536     // the maximum pointer size is 64bit.
    537     Type *MidTy = Type::getInt64Ty(Context);
    538     Temp = CastInst::Create(Instruction::PtrToInt, V, MidTy);
    539 
    540     return CastInst::Create(Instruction::IntToPtr, Temp, DestTy);
    541   }
    542 
    543   return nullptr;
    544 }
    545 
    546 Value *llvm::UpgradeBitCastExpr(unsigned Opc, Constant *C, Type *DestTy) {
    547   if (Opc != Instruction::BitCast)
    548     return nullptr;
    549 
    550   Type *SrcTy = C->getType();
    551   if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
    552       SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
    553     LLVMContext &Context = C->getContext();
    554 
    555     // We have no information about target data layout, so we assume that
    556     // the maximum pointer size is 64bit.
    557     Type *MidTy = Type::getInt64Ty(Context);
    558 
    559     return ConstantExpr::getIntToPtr(ConstantExpr::getPtrToInt(C, MidTy),
    560                                      DestTy);
    561   }
    562 
    563   return nullptr;
    564 }
    565 
    566 /// Check the debug info version number, if it is out-dated, drop the debug
    567 /// info. Return true if module is modified.
    568 bool llvm::UpgradeDebugInfo(Module &M) {
    569   unsigned Version = getDebugMetadataVersionFromModule(M);
    570   if (Version == DEBUG_METADATA_VERSION)
    571     return false;
    572 
    573   bool RetCode = StripDebugInfo(M);
    574   if (RetCode) {
    575     DiagnosticInfoDebugMetadataVersion DiagVersion(M, Version);
    576     M.getContext().diagnose(DiagVersion);
    577   }
    578   return RetCode;
    579 }
    580 
    581 void llvm::UpgradeMDStringConstant(std::string &String) {
    582   const std::string OldPrefix = "llvm.vectorizer.";
    583   if (String.find(OldPrefix) == 0) {
    584         String.replace(0, OldPrefix.size(), "llvm.loop.vectorize.");
    585   }
    586 }
    587