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      1 //===- InstCombineCalls.cpp -----------------------------------------------===//
      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 visitCall and visitInvoke functions.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "InstCombine.h"
     15 #include "llvm/ADT/Statistic.h"
     16 #include "llvm/Analysis/MemoryBuiltins.h"
     17 #include "llvm/IR/DataLayout.h"
     18 #include "llvm/Support/CallSite.h"
     19 #include "llvm/Support/PatternMatch.h"
     20 #include "llvm/Transforms/Utils/BuildLibCalls.h"
     21 #include "llvm/Transforms/Utils/Local.h"
     22 using namespace llvm;
     23 using namespace PatternMatch;
     24 
     25 STATISTIC(NumSimplified, "Number of library calls simplified");
     26 
     27 /// getPromotedType - Return the specified type promoted as it would be to pass
     28 /// though a va_arg area.
     29 static Type *getPromotedType(Type *Ty) {
     30   if (IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
     31     if (ITy->getBitWidth() < 32)
     32       return Type::getInt32Ty(Ty->getContext());
     33   }
     34   return Ty;
     35 }
     36 
     37 /// reduceToSingleValueType - Given an aggregate type which ultimately holds a
     38 /// single scalar element, like {{{type}}} or [1 x type], return type.
     39 static Type *reduceToSingleValueType(Type *T) {
     40   while (!T->isSingleValueType()) {
     41     if (StructType *STy = dyn_cast<StructType>(T)) {
     42       if (STy->getNumElements() == 1)
     43         T = STy->getElementType(0);
     44       else
     45         break;
     46     } else if (ArrayType *ATy = dyn_cast<ArrayType>(T)) {
     47       if (ATy->getNumElements() == 1)
     48         T = ATy->getElementType();
     49       else
     50         break;
     51     } else
     52       break;
     53   }
     54 
     55   return T;
     56 }
     57 
     58 Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
     59   unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), TD);
     60   unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), TD);
     61   unsigned MinAlign = std::min(DstAlign, SrcAlign);
     62   unsigned CopyAlign = MI->getAlignment();
     63 
     64   if (CopyAlign < MinAlign) {
     65     MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
     66                                              MinAlign, false));
     67     return MI;
     68   }
     69 
     70   // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
     71   // load/store.
     72   ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getArgOperand(2));
     73   if (MemOpLength == 0) return 0;
     74 
     75   // Source and destination pointer types are always "i8*" for intrinsic.  See
     76   // if the size is something we can handle with a single primitive load/store.
     77   // A single load+store correctly handles overlapping memory in the memmove
     78   // case.
     79   uint64_t Size = MemOpLength->getLimitedValue();
     80   assert(Size && "0-sized memory transfering should be removed already.");
     81 
     82   if (Size > 8 || (Size&(Size-1)))
     83     return 0;  // If not 1/2/4/8 bytes, exit.
     84 
     85   // Use an integer load+store unless we can find something better.
     86   unsigned SrcAddrSp =
     87     cast<PointerType>(MI->getArgOperand(1)->getType())->getAddressSpace();
     88   unsigned DstAddrSp =
     89     cast<PointerType>(MI->getArgOperand(0)->getType())->getAddressSpace();
     90 
     91   IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3);
     92   Type *NewSrcPtrTy = PointerType::get(IntType, SrcAddrSp);
     93   Type *NewDstPtrTy = PointerType::get(IntType, DstAddrSp);
     94 
     95   // Memcpy forces the use of i8* for the source and destination.  That means
     96   // that if you're using memcpy to move one double around, you'll get a cast
     97   // from double* to i8*.  We'd much rather use a double load+store rather than
     98   // an i64 load+store, here because this improves the odds that the source or
     99   // dest address will be promotable.  See if we can find a better type than the
    100   // integer datatype.
    101   Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
    102   MDNode *CopyMD = 0;
    103   if (StrippedDest != MI->getArgOperand(0)) {
    104     Type *SrcETy = cast<PointerType>(StrippedDest->getType())
    105                                     ->getElementType();
    106     if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
    107       // The SrcETy might be something like {{{double}}} or [1 x double].  Rip
    108       // down through these levels if so.
    109       SrcETy = reduceToSingleValueType(SrcETy);
    110 
    111       if (SrcETy->isSingleValueType()) {
    112         NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
    113         NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
    114 
    115         // If the memcpy has metadata describing the members, see if we can
    116         // get the TBAA tag describing our copy.
    117         if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) {
    118           if (M->getNumOperands() == 3 &&
    119               M->getOperand(0) &&
    120               isa<ConstantInt>(M->getOperand(0)) &&
    121               cast<ConstantInt>(M->getOperand(0))->isNullValue() &&
    122               M->getOperand(1) &&
    123               isa<ConstantInt>(M->getOperand(1)) &&
    124               cast<ConstantInt>(M->getOperand(1))->getValue() == Size &&
    125               M->getOperand(2) &&
    126               isa<MDNode>(M->getOperand(2)))
    127             CopyMD = cast<MDNode>(M->getOperand(2));
    128         }
    129       }
    130     }
    131   }
    132 
    133   // If the memcpy/memmove provides better alignment info than we can
    134   // infer, use it.
    135   SrcAlign = std::max(SrcAlign, CopyAlign);
    136   DstAlign = std::max(DstAlign, CopyAlign);
    137 
    138   Value *Src = Builder->CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
    139   Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
    140   LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
    141   L->setAlignment(SrcAlign);
    142   if (CopyMD)
    143     L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
    144   StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
    145   S->setAlignment(DstAlign);
    146   if (CopyMD)
    147     S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
    148 
    149   // Set the size of the copy to 0, it will be deleted on the next iteration.
    150   MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));
    151   return MI;
    152 }
    153 
    154 Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
    155   unsigned Alignment = getKnownAlignment(MI->getDest(), TD);
    156   if (MI->getAlignment() < Alignment) {
    157     MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
    158                                              Alignment, false));
    159     return MI;
    160   }
    161 
    162   // Extract the length and alignment and fill if they are constant.
    163   ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
    164   ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
    165   if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8))
    166     return 0;
    167   uint64_t Len = LenC->getLimitedValue();
    168   Alignment = MI->getAlignment();
    169   assert(Len && "0-sized memory setting should be removed already.");
    170 
    171   // memset(s,c,n) -> store s, c (for n=1,2,4,8)
    172   if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
    173     Type *ITy = IntegerType::get(MI->getContext(), Len*8);  // n=1 -> i8.
    174 
    175     Value *Dest = MI->getDest();
    176     unsigned DstAddrSp = cast<PointerType>(Dest->getType())->getAddressSpace();
    177     Type *NewDstPtrTy = PointerType::get(ITy, DstAddrSp);
    178     Dest = Builder->CreateBitCast(Dest, NewDstPtrTy);
    179 
    180     // Alignment 0 is identity for alignment 1 for memset, but not store.
    181     if (Alignment == 0) Alignment = 1;
    182 
    183     // Extract the fill value and store.
    184     uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
    185     StoreInst *S = Builder->CreateStore(ConstantInt::get(ITy, Fill), Dest,
    186                                         MI->isVolatile());
    187     S->setAlignment(Alignment);
    188 
    189     // Set the size of the copy to 0, it will be deleted on the next iteration.
    190     MI->setLength(Constant::getNullValue(LenC->getType()));
    191     return MI;
    192   }
    193 
    194   return 0;
    195 }
    196 
    197 /// visitCallInst - CallInst simplification.  This mostly only handles folding
    198 /// of intrinsic instructions.  For normal calls, it allows visitCallSite to do
    199 /// the heavy lifting.
    200 ///
    201 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
    202   if (isFreeCall(&CI, TLI))
    203     return visitFree(CI);
    204 
    205   // If the caller function is nounwind, mark the call as nounwind, even if the
    206   // callee isn't.
    207   if (CI.getParent()->getParent()->doesNotThrow() &&
    208       !CI.doesNotThrow()) {
    209     CI.setDoesNotThrow();
    210     return &CI;
    211   }
    212 
    213   IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
    214   if (!II) return visitCallSite(&CI);
    215 
    216   // Intrinsics cannot occur in an invoke, so handle them here instead of in
    217   // visitCallSite.
    218   if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
    219     bool Changed = false;
    220 
    221     // memmove/cpy/set of zero bytes is a noop.
    222     if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
    223       if (NumBytes->isNullValue())
    224         return EraseInstFromFunction(CI);
    225 
    226       if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
    227         if (CI->getZExtValue() == 1) {
    228           // Replace the instruction with just byte operations.  We would
    229           // transform other cases to loads/stores, but we don't know if
    230           // alignment is sufficient.
    231         }
    232     }
    233 
    234     // No other transformations apply to volatile transfers.
    235     if (MI->isVolatile())
    236       return 0;
    237 
    238     // If we have a memmove and the source operation is a constant global,
    239     // then the source and dest pointers can't alias, so we can change this
    240     // into a call to memcpy.
    241     if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
    242       if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
    243         if (GVSrc->isConstant()) {
    244           Module *M = CI.getParent()->getParent()->getParent();
    245           Intrinsic::ID MemCpyID = Intrinsic::memcpy;
    246           Type *Tys[3] = { CI.getArgOperand(0)->getType(),
    247                            CI.getArgOperand(1)->getType(),
    248                            CI.getArgOperand(2)->getType() };
    249           CI.setCalledFunction(Intrinsic::getDeclaration(M, MemCpyID, Tys));
    250           Changed = true;
    251         }
    252     }
    253 
    254     if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
    255       // memmove(x,x,size) -> noop.
    256       if (MTI->getSource() == MTI->getDest())
    257         return EraseInstFromFunction(CI);
    258     }
    259 
    260     // If we can determine a pointer alignment that is bigger than currently
    261     // set, update the alignment.
    262     if (isa<MemTransferInst>(MI)) {
    263       if (Instruction *I = SimplifyMemTransfer(MI))
    264         return I;
    265     } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
    266       if (Instruction *I = SimplifyMemSet(MSI))
    267         return I;
    268     }
    269 
    270     if (Changed) return II;
    271   }
    272 
    273   switch (II->getIntrinsicID()) {
    274   default: break;
    275   case Intrinsic::objectsize: {
    276     uint64_t Size;
    277     if (getObjectSize(II->getArgOperand(0), Size, TD, TLI))
    278       return ReplaceInstUsesWith(CI, ConstantInt::get(CI.getType(), Size));
    279     return 0;
    280   }
    281   case Intrinsic::bswap: {
    282     Value *IIOperand = II->getArgOperand(0);
    283     Value *X = 0;
    284 
    285     // bswap(bswap(x)) -> x
    286     if (match(IIOperand, m_BSwap(m_Value(X))))
    287         return ReplaceInstUsesWith(CI, X);
    288 
    289     // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
    290     if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) {
    291       unsigned C = X->getType()->getPrimitiveSizeInBits() -
    292         IIOperand->getType()->getPrimitiveSizeInBits();
    293       Value *CV = ConstantInt::get(X->getType(), C);
    294       Value *V = Builder->CreateLShr(X, CV);
    295       return new TruncInst(V, IIOperand->getType());
    296     }
    297     break;
    298   }
    299 
    300   case Intrinsic::powi:
    301     if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
    302       // powi(x, 0) -> 1.0
    303       if (Power->isZero())
    304         return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
    305       // powi(x, 1) -> x
    306       if (Power->isOne())
    307         return ReplaceInstUsesWith(CI, II->getArgOperand(0));
    308       // powi(x, -1) -> 1/x
    309       if (Power->isAllOnesValue())
    310         return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
    311                                           II->getArgOperand(0));
    312     }
    313     break;
    314   case Intrinsic::cttz: {
    315     // If all bits below the first known one are known zero,
    316     // this value is constant.
    317     IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
    318     // FIXME: Try to simplify vectors of integers.
    319     if (!IT) break;
    320     uint32_t BitWidth = IT->getBitWidth();
    321     APInt KnownZero(BitWidth, 0);
    322     APInt KnownOne(BitWidth, 0);
    323     ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
    324     unsigned TrailingZeros = KnownOne.countTrailingZeros();
    325     APInt Mask(APInt::getLowBitsSet(BitWidth, TrailingZeros));
    326     if ((Mask & KnownZero) == Mask)
    327       return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
    328                                  APInt(BitWidth, TrailingZeros)));
    329 
    330     }
    331     break;
    332   case Intrinsic::ctlz: {
    333     // If all bits above the first known one are known zero,
    334     // this value is constant.
    335     IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
    336     // FIXME: Try to simplify vectors of integers.
    337     if (!IT) break;
    338     uint32_t BitWidth = IT->getBitWidth();
    339     APInt KnownZero(BitWidth, 0);
    340     APInt KnownOne(BitWidth, 0);
    341     ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
    342     unsigned LeadingZeros = KnownOne.countLeadingZeros();
    343     APInt Mask(APInt::getHighBitsSet(BitWidth, LeadingZeros));
    344     if ((Mask & KnownZero) == Mask)
    345       return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
    346                                  APInt(BitWidth, LeadingZeros)));
    347 
    348     }
    349     break;
    350   case Intrinsic::uadd_with_overflow: {
    351     Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
    352     IntegerType *IT = cast<IntegerType>(II->getArgOperand(0)->getType());
    353     uint32_t BitWidth = IT->getBitWidth();
    354     APInt LHSKnownZero(BitWidth, 0);
    355     APInt LHSKnownOne(BitWidth, 0);
    356     ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
    357     bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
    358     bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
    359 
    360     if (LHSKnownNegative || LHSKnownPositive) {
    361       APInt RHSKnownZero(BitWidth, 0);
    362       APInt RHSKnownOne(BitWidth, 0);
    363       ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
    364       bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
    365       bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
    366       if (LHSKnownNegative && RHSKnownNegative) {
    367         // The sign bit is set in both cases: this MUST overflow.
    368         // Create a simple add instruction, and insert it into the struct.
    369         Value *Add = Builder->CreateAdd(LHS, RHS);
    370         Add->takeName(&CI);
    371         Constant *V[] = {
    372           UndefValue::get(LHS->getType()),
    373           ConstantInt::getTrue(II->getContext())
    374         };
    375         StructType *ST = cast<StructType>(II->getType());
    376         Constant *Struct = ConstantStruct::get(ST, V);
    377         return InsertValueInst::Create(Struct, Add, 0);
    378       }
    379 
    380       if (LHSKnownPositive && RHSKnownPositive) {
    381         // The sign bit is clear in both cases: this CANNOT overflow.
    382         // Create a simple add instruction, and insert it into the struct.
    383         Value *Add = Builder->CreateNUWAdd(LHS, RHS);
    384         Add->takeName(&CI);
    385         Constant *V[] = {
    386           UndefValue::get(LHS->getType()),
    387           ConstantInt::getFalse(II->getContext())
    388         };
    389         StructType *ST = cast<StructType>(II->getType());
    390         Constant *Struct = ConstantStruct::get(ST, V);
    391         return InsertValueInst::Create(Struct, Add, 0);
    392       }
    393     }
    394   }
    395   // FALL THROUGH uadd into sadd
    396   case Intrinsic::sadd_with_overflow:
    397     // Canonicalize constants into the RHS.
    398     if (isa<Constant>(II->getArgOperand(0)) &&
    399         !isa<Constant>(II->getArgOperand(1))) {
    400       Value *LHS = II->getArgOperand(0);
    401       II->setArgOperand(0, II->getArgOperand(1));
    402       II->setArgOperand(1, LHS);
    403       return II;
    404     }
    405 
    406     // X + undef -> undef
    407     if (isa<UndefValue>(II->getArgOperand(1)))
    408       return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
    409 
    410     if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
    411       // X + 0 -> {X, false}
    412       if (RHS->isZero()) {
    413         Constant *V[] = {
    414           UndefValue::get(II->getArgOperand(0)->getType()),
    415           ConstantInt::getFalse(II->getContext())
    416         };
    417         Constant *Struct =
    418           ConstantStruct::get(cast<StructType>(II->getType()), V);
    419         return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
    420       }
    421     }
    422     break;
    423   case Intrinsic::usub_with_overflow:
    424   case Intrinsic::ssub_with_overflow:
    425     // undef - X -> undef
    426     // X - undef -> undef
    427     if (isa<UndefValue>(II->getArgOperand(0)) ||
    428         isa<UndefValue>(II->getArgOperand(1)))
    429       return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
    430 
    431     if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
    432       // X - 0 -> {X, false}
    433       if (RHS->isZero()) {
    434         Constant *V[] = {
    435           UndefValue::get(II->getArgOperand(0)->getType()),
    436           ConstantInt::getFalse(II->getContext())
    437         };
    438         Constant *Struct =
    439           ConstantStruct::get(cast<StructType>(II->getType()), V);
    440         return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
    441       }
    442     }
    443     break;
    444   case Intrinsic::umul_with_overflow: {
    445     Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
    446     unsigned BitWidth = cast<IntegerType>(LHS->getType())->getBitWidth();
    447 
    448     APInt LHSKnownZero(BitWidth, 0);
    449     APInt LHSKnownOne(BitWidth, 0);
    450     ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
    451     APInt RHSKnownZero(BitWidth, 0);
    452     APInt RHSKnownOne(BitWidth, 0);
    453     ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
    454 
    455     // Get the largest possible values for each operand.
    456     APInt LHSMax = ~LHSKnownZero;
    457     APInt RHSMax = ~RHSKnownZero;
    458 
    459     // If multiplying the maximum values does not overflow then we can turn
    460     // this into a plain NUW mul.
    461     bool Overflow;
    462     LHSMax.umul_ov(RHSMax, Overflow);
    463     if (!Overflow) {
    464       Value *Mul = Builder->CreateNUWMul(LHS, RHS, "umul_with_overflow");
    465       Constant *V[] = {
    466         UndefValue::get(LHS->getType()),
    467         Builder->getFalse()
    468       };
    469       Constant *Struct = ConstantStruct::get(cast<StructType>(II->getType()),V);
    470       return InsertValueInst::Create(Struct, Mul, 0);
    471     }
    472   } // FALL THROUGH
    473   case Intrinsic::smul_with_overflow:
    474     // Canonicalize constants into the RHS.
    475     if (isa<Constant>(II->getArgOperand(0)) &&
    476         !isa<Constant>(II->getArgOperand(1))) {
    477       Value *LHS = II->getArgOperand(0);
    478       II->setArgOperand(0, II->getArgOperand(1));
    479       II->setArgOperand(1, LHS);
    480       return II;
    481     }
    482 
    483     // X * undef -> undef
    484     if (isa<UndefValue>(II->getArgOperand(1)))
    485       return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
    486 
    487     if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
    488       // X*0 -> {0, false}
    489       if (RHSI->isZero())
    490         return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
    491 
    492       // X * 1 -> {X, false}
    493       if (RHSI->equalsInt(1)) {
    494         Constant *V[] = {
    495           UndefValue::get(II->getArgOperand(0)->getType()),
    496           ConstantInt::getFalse(II->getContext())
    497         };
    498         Constant *Struct =
    499           ConstantStruct::get(cast<StructType>(II->getType()), V);
    500         return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
    501       }
    502     }
    503     break;
    504   case Intrinsic::ppc_altivec_lvx:
    505   case Intrinsic::ppc_altivec_lvxl:
    506     // Turn PPC lvx -> load if the pointer is known aligned.
    507     if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
    508       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
    509                                          PointerType::getUnqual(II->getType()));
    510       return new LoadInst(Ptr);
    511     }
    512     break;
    513   case Intrinsic::ppc_altivec_stvx:
    514   case Intrinsic::ppc_altivec_stvxl:
    515     // Turn stvx -> store if the pointer is known aligned.
    516     if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, TD) >= 16) {
    517       Type *OpPtrTy =
    518         PointerType::getUnqual(II->getArgOperand(0)->getType());
    519       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
    520       return new StoreInst(II->getArgOperand(0), Ptr);
    521     }
    522     break;
    523   case Intrinsic::x86_sse_storeu_ps:
    524   case Intrinsic::x86_sse2_storeu_pd:
    525   case Intrinsic::x86_sse2_storeu_dq:
    526     // Turn X86 storeu -> store if the pointer is known aligned.
    527     if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
    528       Type *OpPtrTy =
    529         PointerType::getUnqual(II->getArgOperand(1)->getType());
    530       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy);
    531       return new StoreInst(II->getArgOperand(1), Ptr);
    532     }
    533     break;
    534 
    535   case Intrinsic::x86_sse_cvtss2si:
    536   case Intrinsic::x86_sse_cvtss2si64:
    537   case Intrinsic::x86_sse_cvttss2si:
    538   case Intrinsic::x86_sse_cvttss2si64:
    539   case Intrinsic::x86_sse2_cvtsd2si:
    540   case Intrinsic::x86_sse2_cvtsd2si64:
    541   case Intrinsic::x86_sse2_cvttsd2si:
    542   case Intrinsic::x86_sse2_cvttsd2si64: {
    543     // These intrinsics only demand the 0th element of their input vectors. If
    544     // we can simplify the input based on that, do so now.
    545     unsigned VWidth =
    546       cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
    547     APInt DemandedElts(VWidth, 1);
    548     APInt UndefElts(VWidth, 0);
    549     if (Value *V = SimplifyDemandedVectorElts(II->getArgOperand(0),
    550                                               DemandedElts, UndefElts)) {
    551       II->setArgOperand(0, V);
    552       return II;
    553     }
    554     break;
    555   }
    556 
    557 
    558   case Intrinsic::x86_sse41_pmovsxbw:
    559   case Intrinsic::x86_sse41_pmovsxwd:
    560   case Intrinsic::x86_sse41_pmovsxdq:
    561   case Intrinsic::x86_sse41_pmovzxbw:
    562   case Intrinsic::x86_sse41_pmovzxwd:
    563   case Intrinsic::x86_sse41_pmovzxdq: {
    564     // pmov{s|z}x ignores the upper half of their input vectors.
    565     unsigned VWidth =
    566       cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
    567     unsigned LowHalfElts = VWidth / 2;
    568     APInt InputDemandedElts(APInt::getBitsSet(VWidth, 0, LowHalfElts));
    569     APInt UndefElts(VWidth, 0);
    570     if (Value *TmpV = SimplifyDemandedVectorElts(II->getArgOperand(0),
    571                                                  InputDemandedElts,
    572                                                  UndefElts)) {
    573       II->setArgOperand(0, TmpV);
    574       return II;
    575     }
    576     break;
    577   }
    578 
    579   case Intrinsic::ppc_altivec_vperm:
    580     // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
    581     if (Constant *Mask = dyn_cast<Constant>(II->getArgOperand(2))) {
    582       assert(Mask->getType()->getVectorNumElements() == 16 &&
    583              "Bad type for intrinsic!");
    584 
    585       // Check that all of the elements are integer constants or undefs.
    586       bool AllEltsOk = true;
    587       for (unsigned i = 0; i != 16; ++i) {
    588         Constant *Elt = Mask->getAggregateElement(i);
    589         if (Elt == 0 ||
    590             !(isa<ConstantInt>(Elt) || isa<UndefValue>(Elt))) {
    591           AllEltsOk = false;
    592           break;
    593         }
    594       }
    595 
    596       if (AllEltsOk) {
    597         // Cast the input vectors to byte vectors.
    598         Value *Op0 = Builder->CreateBitCast(II->getArgOperand(0),
    599                                             Mask->getType());
    600         Value *Op1 = Builder->CreateBitCast(II->getArgOperand(1),
    601                                             Mask->getType());
    602         Value *Result = UndefValue::get(Op0->getType());
    603 
    604         // Only extract each element once.
    605         Value *ExtractedElts[32];
    606         memset(ExtractedElts, 0, sizeof(ExtractedElts));
    607 
    608         for (unsigned i = 0; i != 16; ++i) {
    609           if (isa<UndefValue>(Mask->getAggregateElement(i)))
    610             continue;
    611           unsigned Idx =
    612             cast<ConstantInt>(Mask->getAggregateElement(i))->getZExtValue();
    613           Idx &= 31;  // Match the hardware behavior.
    614 
    615           if (ExtractedElts[Idx] == 0) {
    616             ExtractedElts[Idx] =
    617               Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
    618                                             Builder->getInt32(Idx&15));
    619           }
    620 
    621           // Insert this value into the result vector.
    622           Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
    623                                                 Builder->getInt32(i));
    624         }
    625         return CastInst::Create(Instruction::BitCast, Result, CI.getType());
    626       }
    627     }
    628     break;
    629 
    630   case Intrinsic::arm_neon_vld1:
    631   case Intrinsic::arm_neon_vld2:
    632   case Intrinsic::arm_neon_vld3:
    633   case Intrinsic::arm_neon_vld4:
    634   case Intrinsic::arm_neon_vld2lane:
    635   case Intrinsic::arm_neon_vld3lane:
    636   case Intrinsic::arm_neon_vld4lane:
    637   case Intrinsic::arm_neon_vst1:
    638   case Intrinsic::arm_neon_vst2:
    639   case Intrinsic::arm_neon_vst3:
    640   case Intrinsic::arm_neon_vst4:
    641   case Intrinsic::arm_neon_vst2lane:
    642   case Intrinsic::arm_neon_vst3lane:
    643   case Intrinsic::arm_neon_vst4lane: {
    644     unsigned MemAlign = getKnownAlignment(II->getArgOperand(0), TD);
    645     unsigned AlignArg = II->getNumArgOperands() - 1;
    646     ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
    647     if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) {
    648       II->setArgOperand(AlignArg,
    649                         ConstantInt::get(Type::getInt32Ty(II->getContext()),
    650                                          MemAlign, false));
    651       return II;
    652     }
    653     break;
    654   }
    655 
    656   case Intrinsic::arm_neon_vmulls:
    657   case Intrinsic::arm_neon_vmullu: {
    658     Value *Arg0 = II->getArgOperand(0);
    659     Value *Arg1 = II->getArgOperand(1);
    660 
    661     // Handle mul by zero first:
    662     if (isa<ConstantAggregateZero>(Arg0) || isa<ConstantAggregateZero>(Arg1)) {
    663       return ReplaceInstUsesWith(CI, ConstantAggregateZero::get(II->getType()));
    664     }
    665 
    666     // Check for constant LHS & RHS - in this case we just simplify.
    667     bool Zext = (II->getIntrinsicID() == Intrinsic::arm_neon_vmullu);
    668     VectorType *NewVT = cast<VectorType>(II->getType());
    669     unsigned NewWidth = NewVT->getElementType()->getIntegerBitWidth();
    670     if (ConstantDataVector *CV0 = dyn_cast<ConstantDataVector>(Arg0)) {
    671       if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
    672         VectorType* VT = cast<VectorType>(CV0->getType());
    673         SmallVector<Constant*, 4> NewElems;
    674         for (unsigned i = 0; i < VT->getNumElements(); ++i) {
    675           APInt CV0E =
    676             (cast<ConstantInt>(CV0->getAggregateElement(i)))->getValue();
    677           CV0E = Zext ? CV0E.zext(NewWidth) : CV0E.sext(NewWidth);
    678           APInt CV1E =
    679             (cast<ConstantInt>(CV1->getAggregateElement(i)))->getValue();
    680           CV1E = Zext ? CV1E.zext(NewWidth) : CV1E.sext(NewWidth);
    681           NewElems.push_back(
    682             ConstantInt::get(NewVT->getElementType(), CV0E * CV1E));
    683         }
    684         return ReplaceInstUsesWith(CI, ConstantVector::get(NewElems));
    685       }
    686 
    687       // Couldn't simplify - cannonicalize constant to the RHS.
    688       std::swap(Arg0, Arg1);
    689     }
    690 
    691     // Handle mul by one:
    692     if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
    693       if (ConstantInt *Splat =
    694             dyn_cast_or_null<ConstantInt>(CV1->getSplatValue())) {
    695         if (Splat->isOne()) {
    696           if (Zext)
    697             return CastInst::CreateZExtOrBitCast(Arg0, II->getType());
    698           // else
    699           return CastInst::CreateSExtOrBitCast(Arg0, II->getType());
    700         }
    701       }
    702     }
    703 
    704     break;
    705   }
    706 
    707   case Intrinsic::stackrestore: {
    708     // If the save is right next to the restore, remove the restore.  This can
    709     // happen when variable allocas are DCE'd.
    710     if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
    711       if (SS->getIntrinsicID() == Intrinsic::stacksave) {
    712         BasicBlock::iterator BI = SS;
    713         if (&*++BI == II)
    714           return EraseInstFromFunction(CI);
    715       }
    716     }
    717 
    718     // Scan down this block to see if there is another stack restore in the
    719     // same block without an intervening call/alloca.
    720     BasicBlock::iterator BI = II;
    721     TerminatorInst *TI = II->getParent()->getTerminator();
    722     bool CannotRemove = false;
    723     for (++BI; &*BI != TI; ++BI) {
    724       if (isa<AllocaInst>(BI)) {
    725         CannotRemove = true;
    726         break;
    727       }
    728       if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
    729         if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
    730           // If there is a stackrestore below this one, remove this one.
    731           if (II->getIntrinsicID() == Intrinsic::stackrestore)
    732             return EraseInstFromFunction(CI);
    733           // Otherwise, ignore the intrinsic.
    734         } else {
    735           // If we found a non-intrinsic call, we can't remove the stack
    736           // restore.
    737           CannotRemove = true;
    738           break;
    739         }
    740       }
    741     }
    742 
    743     // If the stack restore is in a return, resume, or unwind block and if there
    744     // are no allocas or calls between the restore and the return, nuke the
    745     // restore.
    746     if (!CannotRemove && (isa<ReturnInst>(TI) || isa<ResumeInst>(TI)))
    747       return EraseInstFromFunction(CI);
    748     break;
    749   }
    750   }
    751 
    752   return visitCallSite(II);
    753 }
    754 
    755 // InvokeInst simplification
    756 //
    757 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
    758   return visitCallSite(&II);
    759 }
    760 
    761 /// isSafeToEliminateVarargsCast - If this cast does not affect the value
    762 /// passed through the varargs area, we can eliminate the use of the cast.
    763 static bool isSafeToEliminateVarargsCast(const CallSite CS,
    764                                          const CastInst * const CI,
    765                                          const DataLayout * const TD,
    766                                          const int ix) {
    767   if (!CI->isLosslessCast())
    768     return false;
    769 
    770   // The size of ByVal arguments is derived from the type, so we
    771   // can't change to a type with a different size.  If the size were
    772   // passed explicitly we could avoid this check.
    773   if (!CS.isByValArgument(ix))
    774     return true;
    775 
    776   Type* SrcTy =
    777             cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
    778   Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
    779   if (!SrcTy->isSized() || !DstTy->isSized())
    780     return false;
    781   if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
    782     return false;
    783   return true;
    784 }
    785 
    786 // Try to fold some different type of calls here.
    787 // Currently we're only working with the checking functions, memcpy_chk,
    788 // mempcpy_chk, memmove_chk, memset_chk, strcpy_chk, stpcpy_chk, strncpy_chk,
    789 // strcat_chk and strncat_chk.
    790 Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const DataLayout *TD) {
    791   if (CI->getCalledFunction() == 0) return 0;
    792 
    793   if (Value *With = Simplifier->optimizeCall(CI)) {
    794     ++NumSimplified;
    795     return CI->use_empty() ? CI : ReplaceInstUsesWith(*CI, With);
    796   }
    797 
    798   return 0;
    799 }
    800 
    801 static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) {
    802   // Strip off at most one level of pointer casts, looking for an alloca.  This
    803   // is good enough in practice and simpler than handling any number of casts.
    804   Value *Underlying = TrampMem->stripPointerCasts();
    805   if (Underlying != TrampMem &&
    806       (!Underlying->hasOneUse() || *Underlying->use_begin() != TrampMem))
    807     return 0;
    808   if (!isa<AllocaInst>(Underlying))
    809     return 0;
    810 
    811   IntrinsicInst *InitTrampoline = 0;
    812   for (Value::use_iterator I = TrampMem->use_begin(), E = TrampMem->use_end();
    813        I != E; I++) {
    814     IntrinsicInst *II = dyn_cast<IntrinsicInst>(*I);
    815     if (!II)
    816       return 0;
    817     if (II->getIntrinsicID() == Intrinsic::init_trampoline) {
    818       if (InitTrampoline)
    819         // More than one init_trampoline writes to this value.  Give up.
    820         return 0;
    821       InitTrampoline = II;
    822       continue;
    823     }
    824     if (II->getIntrinsicID() == Intrinsic::adjust_trampoline)
    825       // Allow any number of calls to adjust.trampoline.
    826       continue;
    827     return 0;
    828   }
    829 
    830   // No call to init.trampoline found.
    831   if (!InitTrampoline)
    832     return 0;
    833 
    834   // Check that the alloca is being used in the expected way.
    835   if (InitTrampoline->getOperand(0) != TrampMem)
    836     return 0;
    837 
    838   return InitTrampoline;
    839 }
    840 
    841 static IntrinsicInst *FindInitTrampolineFromBB(IntrinsicInst *AdjustTramp,
    842                                                Value *TrampMem) {
    843   // Visit all the previous instructions in the basic block, and try to find a
    844   // init.trampoline which has a direct path to the adjust.trampoline.
    845   for (BasicBlock::iterator I = AdjustTramp,
    846        E = AdjustTramp->getParent()->begin(); I != E; ) {
    847     Instruction *Inst = --I;
    848     if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
    849       if (II->getIntrinsicID() == Intrinsic::init_trampoline &&
    850           II->getOperand(0) == TrampMem)
    851         return II;
    852     if (Inst->mayWriteToMemory())
    853       return 0;
    854   }
    855   return 0;
    856 }
    857 
    858 // Given a call to llvm.adjust.trampoline, find and return the corresponding
    859 // call to llvm.init.trampoline if the call to the trampoline can be optimized
    860 // to a direct call to a function.  Otherwise return NULL.
    861 //
    862 static IntrinsicInst *FindInitTrampoline(Value *Callee) {
    863   Callee = Callee->stripPointerCasts();
    864   IntrinsicInst *AdjustTramp = dyn_cast<IntrinsicInst>(Callee);
    865   if (!AdjustTramp ||
    866       AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline)
    867     return 0;
    868 
    869   Value *TrampMem = AdjustTramp->getOperand(0);
    870 
    871   if (IntrinsicInst *IT = FindInitTrampolineFromAlloca(TrampMem))
    872     return IT;
    873   if (IntrinsicInst *IT = FindInitTrampolineFromBB(AdjustTramp, TrampMem))
    874     return IT;
    875   return 0;
    876 }
    877 
    878 // visitCallSite - Improvements for call and invoke instructions.
    879 //
    880 Instruction *InstCombiner::visitCallSite(CallSite CS) {
    881   if (isAllocLikeFn(CS.getInstruction(), TLI))
    882     return visitAllocSite(*CS.getInstruction());
    883 
    884   bool Changed = false;
    885 
    886   // If the callee is a pointer to a function, attempt to move any casts to the
    887   // arguments of the call/invoke.
    888   Value *Callee = CS.getCalledValue();
    889   if (!isa<Function>(Callee) && transformConstExprCastCall(CS))
    890     return 0;
    891 
    892   if (Function *CalleeF = dyn_cast<Function>(Callee))
    893     // If the call and callee calling conventions don't match, this call must
    894     // be unreachable, as the call is undefined.
    895     if (CalleeF->getCallingConv() != CS.getCallingConv() &&
    896         // Only do this for calls to a function with a body.  A prototype may
    897         // not actually end up matching the implementation's calling conv for a
    898         // variety of reasons (e.g. it may be written in assembly).
    899         !CalleeF->isDeclaration()) {
    900       Instruction *OldCall = CS.getInstruction();
    901       new StoreInst(ConstantInt::getTrue(Callee->getContext()),
    902                 UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
    903                                   OldCall);
    904       // If OldCall does not return void then replaceAllUsesWith undef.
    905       // This allows ValueHandlers and custom metadata to adjust itself.
    906       if (!OldCall->getType()->isVoidTy())
    907         ReplaceInstUsesWith(*OldCall, UndefValue::get(OldCall->getType()));
    908       if (isa<CallInst>(OldCall))
    909         return EraseInstFromFunction(*OldCall);
    910 
    911       // We cannot remove an invoke, because it would change the CFG, just
    912       // change the callee to a null pointer.
    913       cast<InvokeInst>(OldCall)->setCalledFunction(
    914                                     Constant::getNullValue(CalleeF->getType()));
    915       return 0;
    916     }
    917 
    918   if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
    919     // If CS does not return void then replaceAllUsesWith undef.
    920     // This allows ValueHandlers and custom metadata to adjust itself.
    921     if (!CS.getInstruction()->getType()->isVoidTy())
    922       ReplaceInstUsesWith(*CS.getInstruction(),
    923                           UndefValue::get(CS.getInstruction()->getType()));
    924 
    925     if (isa<InvokeInst>(CS.getInstruction())) {
    926       // Can't remove an invoke because we cannot change the CFG.
    927       return 0;
    928     }
    929 
    930     // This instruction is not reachable, just remove it.  We insert a store to
    931     // undef so that we know that this code is not reachable, despite the fact
    932     // that we can't modify the CFG here.
    933     new StoreInst(ConstantInt::getTrue(Callee->getContext()),
    934                   UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
    935                   CS.getInstruction());
    936 
    937     return EraseInstFromFunction(*CS.getInstruction());
    938   }
    939 
    940   if (IntrinsicInst *II = FindInitTrampoline(Callee))
    941     return transformCallThroughTrampoline(CS, II);
    942 
    943   PointerType *PTy = cast<PointerType>(Callee->getType());
    944   FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
    945   if (FTy->isVarArg()) {
    946     int ix = FTy->getNumParams();
    947     // See if we can optimize any arguments passed through the varargs area of
    948     // the call.
    949     for (CallSite::arg_iterator I = CS.arg_begin() + FTy->getNumParams(),
    950            E = CS.arg_end(); I != E; ++I, ++ix) {
    951       CastInst *CI = dyn_cast<CastInst>(*I);
    952       if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
    953         *I = CI->getOperand(0);
    954         Changed = true;
    955       }
    956     }
    957   }
    958 
    959   if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
    960     // Inline asm calls cannot throw - mark them 'nounwind'.
    961     CS.setDoesNotThrow();
    962     Changed = true;
    963   }
    964 
    965   // Try to optimize the call if possible, we require DataLayout for most of
    966   // this.  None of these calls are seen as possibly dead so go ahead and
    967   // delete the instruction now.
    968   if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
    969     Instruction *I = tryOptimizeCall(CI, TD);
    970     // If we changed something return the result, etc. Otherwise let
    971     // the fallthrough check.
    972     if (I) return EraseInstFromFunction(*I);
    973   }
    974 
    975   return Changed ? CS.getInstruction() : 0;
    976 }
    977 
    978 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
    979 // attempt to move the cast to the arguments of the call/invoke.
    980 //
    981 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
    982   Function *Callee =
    983     dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
    984   if (Callee == 0)
    985     return false;
    986   Instruction *Caller = CS.getInstruction();
    987   const AttributeSet &CallerPAL = CS.getAttributes();
    988 
    989   // Okay, this is a cast from a function to a different type.  Unless doing so
    990   // would cause a type conversion of one of our arguments, change this call to
    991   // be a direct call with arguments casted to the appropriate types.
    992   //
    993   FunctionType *FT = Callee->getFunctionType();
    994   Type *OldRetTy = Caller->getType();
    995   Type *NewRetTy = FT->getReturnType();
    996 
    997   if (NewRetTy->isStructTy())
    998     return false; // TODO: Handle multiple return values.
    999 
   1000   // Check to see if we are changing the return type...
   1001   if (OldRetTy != NewRetTy) {
   1002     if (Callee->isDeclaration() &&
   1003         // Conversion is ok if changing from one pointer type to another or from
   1004         // a pointer to an integer of the same size.
   1005         !((OldRetTy->isPointerTy() || !TD ||
   1006            OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
   1007           (NewRetTy->isPointerTy() || !TD ||
   1008            NewRetTy == TD->getIntPtrType(Caller->getContext()))))
   1009       return false;   // Cannot transform this return value.
   1010 
   1011     if (!Caller->use_empty() &&
   1012         // void -> non-void is handled specially
   1013         !NewRetTy->isVoidTy() &&
   1014         !CastInst::isBitCastable(NewRetTy, OldRetTy))
   1015       return false;   // Cannot transform this return value.
   1016 
   1017     if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
   1018       AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex);
   1019       if (RAttrs.
   1020           hasAttributes(AttributeFuncs::
   1021                         typeIncompatible(NewRetTy, AttributeSet::ReturnIndex),
   1022                         AttributeSet::ReturnIndex))
   1023         return false;   // Attribute not compatible with transformed value.
   1024     }
   1025 
   1026     // If the callsite is an invoke instruction, and the return value is used by
   1027     // a PHI node in a successor, we cannot change the return type of the call
   1028     // because there is no place to put the cast instruction (without breaking
   1029     // the critical edge).  Bail out in this case.
   1030     if (!Caller->use_empty())
   1031       if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
   1032         for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
   1033              UI != E; ++UI)
   1034           if (PHINode *PN = dyn_cast<PHINode>(*UI))
   1035             if (PN->getParent() == II->getNormalDest() ||
   1036                 PN->getParent() == II->getUnwindDest())
   1037               return false;
   1038   }
   1039 
   1040   unsigned NumActualArgs = CS.arg_size();
   1041   unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
   1042 
   1043   CallSite::arg_iterator AI = CS.arg_begin();
   1044   for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
   1045     Type *ParamTy = FT->getParamType(i);
   1046     Type *ActTy = (*AI)->getType();
   1047 
   1048     if (!CastInst::isBitCastable(ActTy, ParamTy)) {
   1049       return false;   // Cannot transform this parameter value.
   1050     }
   1051 
   1052     if (AttrBuilder(CallerPAL.getParamAttributes(i + 1), i + 1).
   1053           hasAttributes(AttributeFuncs::
   1054                         typeIncompatible(ParamTy, i + 1), i + 1))
   1055       return false;   // Attribute not compatible with transformed value.
   1056 
   1057     // If the parameter is passed as a byval argument, then we have to have a
   1058     // sized type and the sized type has to have the same size as the old type.
   1059     if (ParamTy != ActTy &&
   1060         CallerPAL.getParamAttributes(i + 1).hasAttribute(i + 1,
   1061                                                          Attribute::ByVal)) {
   1062       PointerType *ParamPTy = dyn_cast<PointerType>(ParamTy);
   1063       if (ParamPTy == 0 || !ParamPTy->getElementType()->isSized() || TD == 0)
   1064         return false;
   1065 
   1066       Type *CurElTy = cast<PointerType>(ActTy)->getElementType();
   1067       if (TD->getTypeAllocSize(CurElTy) !=
   1068           TD->getTypeAllocSize(ParamPTy->getElementType()))
   1069         return false;
   1070     }
   1071 
   1072     // Converting from one pointer type to another or between a pointer and an
   1073     // integer of the same size is safe even if we do not have a body.
   1074     bool isConvertible = ActTy == ParamTy ||
   1075       (TD && ((ParamTy->isPointerTy() ||
   1076       ParamTy == TD->getIntPtrType(Caller->getContext())) &&
   1077               (ActTy->isPointerTy() ||
   1078               ActTy == TD->getIntPtrType(Caller->getContext()))));
   1079     if (Callee->isDeclaration() && !isConvertible)
   1080       return false;
   1081   }
   1082 
   1083   if (Callee->isDeclaration()) {
   1084     // Do not delete arguments unless we have a function body.
   1085     if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
   1086       return false;
   1087 
   1088     // If the callee is just a declaration, don't change the varargsness of the
   1089     // call.  We don't want to introduce a varargs call where one doesn't
   1090     // already exist.
   1091     PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
   1092     if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
   1093       return false;
   1094 
   1095     // If both the callee and the cast type are varargs, we still have to make
   1096     // sure the number of fixed parameters are the same or we have the same
   1097     // ABI issues as if we introduce a varargs call.
   1098     if (FT->isVarArg() &&
   1099         cast<FunctionType>(APTy->getElementType())->isVarArg() &&
   1100         FT->getNumParams() !=
   1101         cast<FunctionType>(APTy->getElementType())->getNumParams())
   1102       return false;
   1103   }
   1104 
   1105   if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
   1106       !CallerPAL.isEmpty())
   1107     // In this case we have more arguments than the new function type, but we
   1108     // won't be dropping them.  Check that these extra arguments have attributes
   1109     // that are compatible with being a vararg call argument.
   1110     for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
   1111       unsigned Index = CallerPAL.getSlotIndex(i - 1);
   1112       if (Index <= FT->getNumParams())
   1113         break;
   1114 
   1115       // Check if it has an attribute that's incompatible with varargs.
   1116       AttributeSet PAttrs = CallerPAL.getSlotAttributes(i - 1);
   1117       if (PAttrs.hasAttribute(Index, Attribute::StructRet))
   1118         return false;
   1119     }
   1120 
   1121 
   1122   // Okay, we decided that this is a safe thing to do: go ahead and start
   1123   // inserting cast instructions as necessary.
   1124   std::vector<Value*> Args;
   1125   Args.reserve(NumActualArgs);
   1126   SmallVector<AttributeSet, 8> attrVec;
   1127   attrVec.reserve(NumCommonArgs);
   1128 
   1129   // Get any return attributes.
   1130   AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex);
   1131 
   1132   // If the return value is not being used, the type may not be compatible
   1133   // with the existing attributes.  Wipe out any problematic attributes.
   1134   RAttrs.
   1135     removeAttributes(AttributeFuncs::
   1136                      typeIncompatible(NewRetTy, AttributeSet::ReturnIndex),
   1137                      AttributeSet::ReturnIndex);
   1138 
   1139   // Add the new return attributes.
   1140   if (RAttrs.hasAttributes())
   1141     attrVec.push_back(AttributeSet::get(Caller->getContext(),
   1142                                         AttributeSet::ReturnIndex, RAttrs));
   1143 
   1144   AI = CS.arg_begin();
   1145   for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
   1146     Type *ParamTy = FT->getParamType(i);
   1147 
   1148     if ((*AI)->getType() == ParamTy) {
   1149       Args.push_back(*AI);
   1150     } else {
   1151       Args.push_back(Builder->CreateBitCast(*AI, ParamTy));
   1152     }
   1153 
   1154     // Add any parameter attributes.
   1155     AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1);
   1156     if (PAttrs.hasAttributes())
   1157       attrVec.push_back(AttributeSet::get(Caller->getContext(), i + 1,
   1158                                           PAttrs));
   1159   }
   1160 
   1161   // If the function takes more arguments than the call was taking, add them
   1162   // now.
   1163   for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
   1164     Args.push_back(Constant::getNullValue(FT->getParamType(i)));
   1165 
   1166   // If we are removing arguments to the function, emit an obnoxious warning.
   1167   if (FT->getNumParams() < NumActualArgs) {
   1168     // TODO: if (!FT->isVarArg()) this call may be unreachable. PR14722
   1169     if (FT->isVarArg()) {
   1170       // Add all of the arguments in their promoted form to the arg list.
   1171       for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
   1172         Type *PTy = getPromotedType((*AI)->getType());
   1173         if (PTy != (*AI)->getType()) {
   1174           // Must promote to pass through va_arg area!
   1175           Instruction::CastOps opcode =
   1176             CastInst::getCastOpcode(*AI, false, PTy, false);
   1177           Args.push_back(Builder->CreateCast(opcode, *AI, PTy));
   1178         } else {
   1179           Args.push_back(*AI);
   1180         }
   1181 
   1182         // Add any parameter attributes.
   1183         AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1);
   1184         if (PAttrs.hasAttributes())
   1185           attrVec.push_back(AttributeSet::get(FT->getContext(), i + 1,
   1186                                               PAttrs));
   1187       }
   1188     }
   1189   }
   1190 
   1191   AttributeSet FnAttrs = CallerPAL.getFnAttributes();
   1192   if (CallerPAL.hasAttributes(AttributeSet::FunctionIndex))
   1193     attrVec.push_back(AttributeSet::get(Callee->getContext(), FnAttrs));
   1194 
   1195   if (NewRetTy->isVoidTy())
   1196     Caller->setName("");   // Void type should not have a name.
   1197 
   1198   const AttributeSet &NewCallerPAL = AttributeSet::get(Callee->getContext(),
   1199                                                        attrVec);
   1200 
   1201   Instruction *NC;
   1202   if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
   1203     NC = Builder->CreateInvoke(Callee, II->getNormalDest(),
   1204                                II->getUnwindDest(), Args);
   1205     NC->takeName(II);
   1206     cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
   1207     cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
   1208   } else {
   1209     CallInst *CI = cast<CallInst>(Caller);
   1210     NC = Builder->CreateCall(Callee, Args);
   1211     NC->takeName(CI);
   1212     if (CI->isTailCall())
   1213       cast<CallInst>(NC)->setTailCall();
   1214     cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
   1215     cast<CallInst>(NC)->setAttributes(NewCallerPAL);
   1216   }
   1217 
   1218   // Insert a cast of the return type as necessary.
   1219   Value *NV = NC;
   1220   if (OldRetTy != NV->getType() && !Caller->use_empty()) {
   1221     if (!NV->getType()->isVoidTy()) {
   1222       NV = NC = CastInst::Create(CastInst::BitCast, NC, OldRetTy);
   1223       NC->setDebugLoc(Caller->getDebugLoc());
   1224 
   1225       // If this is an invoke instruction, we should insert it after the first
   1226       // non-phi, instruction in the normal successor block.
   1227       if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
   1228         BasicBlock::iterator I = II->getNormalDest()->getFirstInsertionPt();
   1229         InsertNewInstBefore(NC, *I);
   1230       } else {
   1231         // Otherwise, it's a call, just insert cast right after the call.
   1232         InsertNewInstBefore(NC, *Caller);
   1233       }
   1234       Worklist.AddUsersToWorkList(*Caller);
   1235     } else {
   1236       NV = UndefValue::get(Caller->getType());
   1237     }
   1238   }
   1239 
   1240   if (!Caller->use_empty())
   1241     ReplaceInstUsesWith(*Caller, NV);
   1242 
   1243   EraseInstFromFunction(*Caller);
   1244   return true;
   1245 }
   1246 
   1247 // transformCallThroughTrampoline - Turn a call to a function created by
   1248 // init_trampoline / adjust_trampoline intrinsic pair into a direct call to the
   1249 // underlying function.
   1250 //
   1251 Instruction *
   1252 InstCombiner::transformCallThroughTrampoline(CallSite CS,
   1253                                              IntrinsicInst *Tramp) {
   1254   Value *Callee = CS.getCalledValue();
   1255   PointerType *PTy = cast<PointerType>(Callee->getType());
   1256   FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
   1257   const AttributeSet &Attrs = CS.getAttributes();
   1258 
   1259   // If the call already has the 'nest' attribute somewhere then give up -
   1260   // otherwise 'nest' would occur twice after splicing in the chain.
   1261   if (Attrs.hasAttrSomewhere(Attribute::Nest))
   1262     return 0;
   1263 
   1264   assert(Tramp &&
   1265          "transformCallThroughTrampoline called with incorrect CallSite.");
   1266 
   1267   Function *NestF =cast<Function>(Tramp->getArgOperand(1)->stripPointerCasts());
   1268   PointerType *NestFPTy = cast<PointerType>(NestF->getType());
   1269   FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
   1270 
   1271   const AttributeSet &NestAttrs = NestF->getAttributes();
   1272   if (!NestAttrs.isEmpty()) {
   1273     unsigned NestIdx = 1;
   1274     Type *NestTy = 0;
   1275     AttributeSet NestAttr;
   1276 
   1277     // Look for a parameter marked with the 'nest' attribute.
   1278     for (FunctionType::param_iterator I = NestFTy->param_begin(),
   1279          E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
   1280       if (NestAttrs.hasAttribute(NestIdx, Attribute::Nest)) {
   1281         // Record the parameter type and any other attributes.
   1282         NestTy = *I;
   1283         NestAttr = NestAttrs.getParamAttributes(NestIdx);
   1284         break;
   1285       }
   1286 
   1287     if (NestTy) {
   1288       Instruction *Caller = CS.getInstruction();
   1289       std::vector<Value*> NewArgs;
   1290       NewArgs.reserve(CS.arg_size() + 1);
   1291 
   1292       SmallVector<AttributeSet, 8> NewAttrs;
   1293       NewAttrs.reserve(Attrs.getNumSlots() + 1);
   1294 
   1295       // Insert the nest argument into the call argument list, which may
   1296       // mean appending it.  Likewise for attributes.
   1297 
   1298       // Add any result attributes.
   1299       if (Attrs.hasAttributes(AttributeSet::ReturnIndex))
   1300         NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
   1301                                              Attrs.getRetAttributes()));
   1302 
   1303       {
   1304         unsigned Idx = 1;
   1305         CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
   1306         do {
   1307           if (Idx == NestIdx) {
   1308             // Add the chain argument and attributes.
   1309             Value *NestVal = Tramp->getArgOperand(2);
   1310             if (NestVal->getType() != NestTy)
   1311               NestVal = Builder->CreateBitCast(NestVal, NestTy, "nest");
   1312             NewArgs.push_back(NestVal);
   1313             NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
   1314                                                  NestAttr));
   1315           }
   1316 
   1317           if (I == E)
   1318             break;
   1319 
   1320           // Add the original argument and attributes.
   1321           NewArgs.push_back(*I);
   1322           AttributeSet Attr = Attrs.getParamAttributes(Idx);
   1323           if (Attr.hasAttributes(Idx)) {
   1324             AttrBuilder B(Attr, Idx);
   1325             NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
   1326                                                  Idx + (Idx >= NestIdx), B));
   1327           }
   1328 
   1329           ++Idx, ++I;
   1330         } while (1);
   1331       }
   1332 
   1333       // Add any function attributes.
   1334       if (Attrs.hasAttributes(AttributeSet::FunctionIndex))
   1335         NewAttrs.push_back(AttributeSet::get(FTy->getContext(),
   1336                                              Attrs.getFnAttributes()));
   1337 
   1338       // The trampoline may have been bitcast to a bogus type (FTy).
   1339       // Handle this by synthesizing a new function type, equal to FTy
   1340       // with the chain parameter inserted.
   1341 
   1342       std::vector<Type*> NewTypes;
   1343       NewTypes.reserve(FTy->getNumParams()+1);
   1344 
   1345       // Insert the chain's type into the list of parameter types, which may
   1346       // mean appending it.
   1347       {
   1348         unsigned Idx = 1;
   1349         FunctionType::param_iterator I = FTy->param_begin(),
   1350           E = FTy->param_end();
   1351 
   1352         do {
   1353           if (Idx == NestIdx)
   1354             // Add the chain's type.
   1355             NewTypes.push_back(NestTy);
   1356 
   1357           if (I == E)
   1358             break;
   1359 
   1360           // Add the original type.
   1361           NewTypes.push_back(*I);
   1362 
   1363           ++Idx, ++I;
   1364         } while (1);
   1365       }
   1366 
   1367       // Replace the trampoline call with a direct call.  Let the generic
   1368       // code sort out any function type mismatches.
   1369       FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
   1370                                                 FTy->isVarArg());
   1371       Constant *NewCallee =
   1372         NestF->getType() == PointerType::getUnqual(NewFTy) ?
   1373         NestF : ConstantExpr::getBitCast(NestF,
   1374                                          PointerType::getUnqual(NewFTy));
   1375       const AttributeSet &NewPAL =
   1376           AttributeSet::get(FTy->getContext(), NewAttrs);
   1377 
   1378       Instruction *NewCaller;
   1379       if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
   1380         NewCaller = InvokeInst::Create(NewCallee,
   1381                                        II->getNormalDest(), II->getUnwindDest(),
   1382                                        NewArgs);
   1383         cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
   1384         cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
   1385       } else {
   1386         NewCaller = CallInst::Create(NewCallee, NewArgs);
   1387         if (cast<CallInst>(Caller)->isTailCall())
   1388           cast<CallInst>(NewCaller)->setTailCall();
   1389         cast<CallInst>(NewCaller)->
   1390           setCallingConv(cast<CallInst>(Caller)->getCallingConv());
   1391         cast<CallInst>(NewCaller)->setAttributes(NewPAL);
   1392       }
   1393 
   1394       return NewCaller;
   1395     }
   1396   }
   1397 
   1398   // Replace the trampoline call with a direct call.  Since there is no 'nest'
   1399   // parameter, there is no need to adjust the argument list.  Let the generic
   1400   // code sort out any function type mismatches.
   1401   Constant *NewCallee =
   1402     NestF->getType() == PTy ? NestF :
   1403                               ConstantExpr::getBitCast(NestF, PTy);
   1404   CS.setCalledFunction(NewCallee);
   1405   return CS.getInstruction();
   1406 }
   1407