LCOV - code coverage report
Current view: top level - lib/IR - ConstantFold.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 804 917 87.7 %
Date: 2018-07-13 00:08:38 Functions: 25 25 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
       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 folding of constants for LLVM.  This implements the
      11             : // (internal) ConstantFold.h interface, which is used by the
      12             : // ConstantExpr::get* methods to automatically fold constants when possible.
      13             : //
      14             : // The current constant folding implementation is implemented in two pieces: the
      15             : // pieces that don't need DataLayout, and the pieces that do. This is to avoid
      16             : // a dependence in IR on Target.
      17             : //
      18             : //===----------------------------------------------------------------------===//
      19             : 
      20             : #include "ConstantFold.h"
      21             : #include "llvm/ADT/APSInt.h"
      22             : #include "llvm/ADT/SmallVector.h"
      23             : #include "llvm/IR/Constants.h"
      24             : #include "llvm/IR/DerivedTypes.h"
      25             : #include "llvm/IR/Function.h"
      26             : #include "llvm/IR/GetElementPtrTypeIterator.h"
      27             : #include "llvm/IR/GlobalAlias.h"
      28             : #include "llvm/IR/GlobalVariable.h"
      29             : #include "llvm/IR/Instructions.h"
      30             : #include "llvm/IR/Operator.h"
      31             : #include "llvm/IR/PatternMatch.h"
      32             : #include "llvm/Support/ErrorHandling.h"
      33             : #include "llvm/Support/ManagedStatic.h"
      34             : #include "llvm/Support/MathExtras.h"
      35             : using namespace llvm;
      36             : using namespace llvm::PatternMatch;
      37             : 
      38             : //===----------------------------------------------------------------------===//
      39             : //                ConstantFold*Instruction Implementations
      40             : //===----------------------------------------------------------------------===//
      41             : 
      42             : /// Convert the specified vector Constant node to the specified vector type.
      43             : /// At this point, we know that the elements of the input vector constant are
      44             : /// all simple integer or FP values.
      45         186 : static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) {
      46             : 
      47         186 :   if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy);
      48          98 :   if (CV->isNullValue()) return Constant::getNullValue(DstTy);
      49             : 
      50             :   // If this cast changes element count then we can't handle it here:
      51             :   // doing so requires endianness information.  This should be handled by
      52             :   // Analysis/ConstantFolding.cpp
      53          98 :   unsigned NumElts = DstTy->getNumElements();
      54         196 :   if (NumElts != CV->getType()->getVectorNumElements())
      55             :     return nullptr;
      56             : 
      57           2 :   Type *DstEltTy = DstTy->getElementType();
      58             : 
      59             :   SmallVector<Constant*, 16> Result;
      60           2 :   Type *Ty = IntegerType::get(CV->getContext(), 32);
      61          10 :   for (unsigned i = 0; i != NumElts; ++i) {
      62             :     Constant *C =
      63           4 :       ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i));
      64           4 :     C = ConstantExpr::getBitCast(C, DstEltTy);
      65           4 :     Result.push_back(C);
      66             :   }
      67             : 
      68           2 :   return ConstantVector::get(Result);
      69             : }
      70             : 
      71             : /// This function determines which opcode to use to fold two constant cast
      72             : /// expressions together. It uses CastInst::isEliminableCastPair to determine
      73             : /// the opcode. Consequently its just a wrapper around that function.
      74             : /// Determine if it is valid to fold a cast of a cast
      75             : static unsigned
      76      532386 : foldConstantCastPair(
      77             :   unsigned opc,          ///< opcode of the second cast constant expression
      78             :   ConstantExpr *Op,      ///< the first cast constant expression
      79             :   Type *DstTy            ///< destination type of the first cast
      80             : ) {
      81             :   assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
      82             :   assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
      83             :   assert(CastInst::isCast(opc) && "Invalid cast opcode");
      84             : 
      85             :   // The types and opcodes for the two Cast constant expressions
      86      532386 :   Type *SrcTy = Op->getOperand(0)->getType();
      87      532386 :   Type *MidTy = Op->getType();
      88             :   Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
      89             :   Instruction::CastOps secondOp = Instruction::CastOps(opc);
      90             : 
      91             :   // Assume that pointers are never more than 64 bits wide, and only use this
      92             :   // for the middle type. Otherwise we could end up folding away illegal
      93             :   // bitcasts between address spaces with different sizes.
      94      532386 :   IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext());
      95             : 
      96             :   // Let CastInst::isEliminableCastPair do the heavy lifting.
      97             :   return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
      98      532386 :                                         nullptr, FakeIntPtrTy, nullptr);
      99             : }
     100             : 
     101     1629815 : static Constant *FoldBitCast(Constant *V, Type *DestTy) {
     102     1629815 :   Type *SrcTy = V->getType();
     103     1629815 :   if (SrcTy == DestTy)
     104             :     return V; // no-op cast
     105             : 
     106             :   // Check to see if we are casting a pointer to an aggregate to a pointer to
     107             :   // the first element.  If so, return the appropriate GEP instruction.
     108             :   if (PointerType *PTy = dyn_cast<PointerType>(V->getType()))
     109             :     if (PointerType *DPTy = dyn_cast<PointerType>(DestTy))
     110             :       if (PTy->getAddressSpace() == DPTy->getAddressSpace()
     111     1627413 :           && PTy->getElementType()->isSized()) {
     112             :         SmallVector<Value*, 8> IdxList;
     113             :         Value *Zero =
     114     1580278 :           Constant::getNullValue(Type::getInt32Ty(DPTy->getContext()));
     115     1580278 :         IdxList.push_back(Zero);
     116     1580278 :         Type *ElTy = PTy->getElementType();
     117     3072019 :         while (ElTy != DPTy->getElementType()) {
     118             :           if (StructType *STy = dyn_cast<StructType>(ElTy)) {
     119       29015 :             if (STy->getNumElements() == 0) break;
     120       28986 :             ElTy = STy->getElementType(0);
     121       28986 :             IdxList.push_back(Zero);
     122             :           } else if (SequentialType *STy =
     123             :                      dyn_cast<SequentialType>(ElTy)) {
     124     1462755 :             ElTy = STy->getElementType();
     125     1462755 :             IdxList.push_back(Zero);
     126             :           } else {
     127             :             break;
     128             :           }
     129             :         }
     130             : 
     131     1580278 :         if (ElTy == DPTy->getElementType())
     132             :           // This GEP is inbounds because all indices are zero.
     133       20862 :           return ConstantExpr::getInBoundsGetElementPtr(PTy->getElementType(),
     134             :                                                         V, IdxList);
     135             :       }
     136             : 
     137             :   // Handle casts from one vector constant to another.  We know that the src
     138             :   // and dest type have the same size (otherwise its an illegal cast).
     139             :   if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
     140         302 :     if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
     141             :       assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
     142             :              "Not cast between same sized vectors!");
     143             :       SrcTy = nullptr;
     144             :       // First, check for null.  Undef is already handled.
     145         186 :       if (isa<ConstantAggregateZero>(V))
     146           0 :         return Constant::getNullValue(DestTy);
     147             : 
     148             :       // Handle ConstantVector and ConstantAggregateVector.
     149         186 :       return BitCastConstantVector(V, DestPTy);
     150             :     }
     151             : 
     152             :     // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts
     153             :     // This allows for other simplifications (although some of them
     154             :     // can only be handled by Analysis/ConstantFolding.cpp).
     155         116 :     if (isa<ConstantInt>(V) || isa<ConstantFP>(V))
     156          87 :       return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy);
     157             :   }
     158             : 
     159             :   // Finally, implement bitcast folding now.   The code below doesn't handle
     160             :   // bitcast right.
     161     3217360 :   if (isa<ConstantPointerNull>(V))  // ptr->ptr cast.
     162           0 :     return ConstantPointerNull::get(cast<PointerType>(DestTy));
     163             : 
     164             :   // Handle integral constant input.
     165             :   if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     166         581 :     if (DestTy->isIntegerTy())
     167             :       // Integral -> Integral. This is a no-op because the bit widths must
     168             :       // be the same. Consequently, we just fold to V.
     169             :       return V;
     170             : 
     171             :     // See note below regarding the PPC_FP128 restriction.
     172         577 :     if (DestTy->isFloatingPointTy() && !DestTy->isPPC_FP128Ty())
     173         577 :       return ConstantFP::get(DestTy->getContext(),
     174        1154 :                              APFloat(DestTy->getFltSemantics(),
     175         577 :                                      CI->getValue()));
     176             : 
     177             :     // Otherwise, can't fold this (vector?)
     178             :     return nullptr;
     179             :   }
     180             : 
     181             :   // Handle ConstantFP input: FP -> Integral.
     182             :   if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
     183             :     // PPC_FP128 is really the sum of two consecutive doubles, where the first
     184             :     // double is always stored first in memory, regardless of the target
     185             :     // endianness. The memory layout of i128, however, depends on the target
     186             :     // endianness, and so we can't fold this without target endianness
     187             :     // information. This should instead be handled by
     188             :     // Analysis/ConstantFolding.cpp
     189        2668 :     if (FP->getType()->isPPC_FP128Ty())
     190             :       return nullptr;
     191             : 
     192             :     // Make sure dest type is compatible with the folded integer constant.
     193        1325 :     if (!DestTy->isIntegerTy())
     194             :       return nullptr;
     195             : 
     196        1320 :     return ConstantInt::get(FP->getContext(),
     197        3960 :                             FP->getValueAPF().bitcastToAPInt());
     198             :   }
     199             : 
     200             :   return nullptr;
     201             : }
     202             : 
     203             : 
     204             : /// V is an integer constant which only has a subset of its bytes used.
     205             : /// The bytes used are indicated by ByteStart (which is the first byte used,
     206             : /// counting from the least significant byte) and ByteSize, which is the number
     207             : /// of bytes used.
     208             : ///
     209             : /// This function analyzes the specified constant to see if the specified byte
     210             : /// range can be returned as a simplified constant.  If so, the constant is
     211             : /// returned, otherwise null is returned.
     212        1250 : static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart,
     213             :                                       unsigned ByteSize) {
     214             :   assert(C->getType()->isIntegerTy() &&
     215             :          (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 &&
     216             :          "Non-byte sized integer input");
     217        2500 :   unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8;
     218             :   assert(ByteSize && "Must be accessing some piece");
     219             :   assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input");
     220             :   assert(ByteSize != CSize && "Should not extract everything");
     221             : 
     222             :   // Constant Integers are simple.
     223             :   if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
     224             :     APInt V = CI->getValue();
     225          18 :     if (ByteStart)
     226          13 :       V.lshrInPlace(ByteStart*8);
     227          36 :     V = V.trunc(ByteSize*8);
     228          18 :     return ConstantInt::get(CI->getContext(), V);
     229             :   }
     230             : 
     231             :   // In the input is a constant expr, we might be able to recursively simplify.
     232             :   // If not, we definitely can't do anything.
     233             :   ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
     234             :   if (!CE) return nullptr;
     235             : 
     236        1232 :   switch (CE->getOpcode()) {
     237             :   default: return nullptr;
     238             :   case Instruction::Or: {
     239          14 :     Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize);
     240          14 :     if (!RHS)
     241             :       return nullptr;
     242             : 
     243             :     // X | -1 -> -1.
     244             :     if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS))
     245          12 :       if (RHSC->isMinusOne())
     246             :         return RHSC;
     247             : 
     248          14 :     Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize);
     249          14 :     if (!LHS)
     250             :       return nullptr;
     251           7 :     return ConstantExpr::getOr(LHS, RHS);
     252             :   }
     253             :   case Instruction::And: {
     254          11 :     Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize);
     255          11 :     if (!RHS)
     256             :       return nullptr;
     257             : 
     258             :     // X & 0 -> 0.
     259          11 :     if (RHS->isNullValue())
     260             :       return RHS;
     261             : 
     262           7 :     Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize);
     263           7 :     if (!LHS)
     264             :       return nullptr;
     265           3 :     return ConstantExpr::getAnd(LHS, RHS);
     266             :   }
     267             :   case Instruction::LShr: {
     268             :     ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
     269             :     if (!Amt)
     270             :       return nullptr;
     271          36 :     unsigned ShAmt = Amt->getZExtValue();
     272             :     // Cannot analyze non-byte shifts.
     273          36 :     if ((ShAmt & 7) != 0)
     274             :       return nullptr;
     275          36 :     ShAmt >>= 3;
     276             : 
     277             :     // If the extract is known to be all zeros, return zero.
     278          36 :     if (ByteStart >= CSize-ShAmt)
     279           0 :       return Constant::getNullValue(IntegerType::get(CE->getContext(),
     280           0 :                                                      ByteSize*8));
     281             :     // If the extract is known to be fully in the input, extract it.
     282          36 :     if (ByteStart+ByteSize+ShAmt <= CSize)
     283          72 :       return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize);
     284             : 
     285             :     // TODO: Handle the 'partially zero' case.
     286             :     return nullptr;
     287             :   }
     288             : 
     289             :   case Instruction::Shl: {
     290             :     ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
     291             :     if (!Amt)
     292             :       return nullptr;
     293          20 :     unsigned ShAmt = Amt->getZExtValue();
     294             :     // Cannot analyze non-byte shifts.
     295          20 :     if ((ShAmt & 7) != 0)
     296             :       return nullptr;
     297          16 :     ShAmt >>= 3;
     298             : 
     299             :     // If the extract is known to be all zeros, return zero.
     300          16 :     if (ByteStart+ByteSize <= ShAmt)
     301           5 :       return Constant::getNullValue(IntegerType::get(CE->getContext(),
     302           5 :                                                      ByteSize*8));
     303             :     // If the extract is known to be fully in the input, extract it.
     304          11 :     if (ByteStart >= ShAmt)
     305          10 :       return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize);
     306             : 
     307             :     // TODO: Handle the 'partially zero' case.
     308             :     return nullptr;
     309             :   }
     310             : 
     311             :   case Instruction::ZExt: {
     312             :     unsigned SrcBitSize =
     313          12 :       cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth();
     314             : 
     315             :     // If extracting something that is completely zero, return 0.
     316          12 :     if (ByteStart*8 >= SrcBitSize)
     317           6 :       return Constant::getNullValue(IntegerType::get(CE->getContext(),
     318           6 :                                                      ByteSize*8));
     319             : 
     320             :     // If exactly extracting the input, return it.
     321           6 :     if (ByteStart == 0 && ByteSize*8 == SrcBitSize)
     322             :       return CE->getOperand(0);
     323             : 
     324             :     // If extracting something completely in the input, if the input is a
     325             :     // multiple of 8 bits, recurse.
     326           1 :     if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize)
     327           0 :       return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize);
     328             : 
     329             :     // Otherwise, if extracting a subset of the input, which is not multiple of
     330             :     // 8 bits, do a shift and trunc to get the bits.
     331           1 :     if ((ByteStart+ByteSize)*8 < SrcBitSize) {
     332             :       assert((SrcBitSize&7) && "Shouldn't get byte sized case here");
     333             :       Constant *Res = CE->getOperand(0);
     334           0 :       if (ByteStart)
     335           0 :         Res = ConstantExpr::getLShr(Res,
     336             :                                  ConstantInt::get(Res->getType(), ByteStart*8));
     337           0 :       return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(),
     338           0 :                                                           ByteSize*8));
     339             :     }
     340             : 
     341             :     // TODO: Handle the 'partially zero' case.
     342             :     return nullptr;
     343             :   }
     344             :   }
     345             : }
     346             : 
     347             : /// Return a ConstantExpr with type DestTy for sizeof on Ty, with any known
     348             : /// factors factored out. If Folded is false, return null if no factoring was
     349             : /// possible, to avoid endlessly bouncing an unfoldable expression back into the
     350             : /// top-level folder.
     351         749 : static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, bool Folded) {
     352             :   if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
     353          21 :     Constant *N = ConstantInt::get(DestTy, ATy->getNumElements());
     354          21 :     Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true);
     355          21 :     return ConstantExpr::getNUWMul(E, N);
     356             :   }
     357             : 
     358             :   if (StructType *STy = dyn_cast<StructType>(Ty))
     359         112 :     if (!STy->isPacked()) {
     360         112 :       unsigned NumElems = STy->getNumElements();
     361             :       // An empty struct has size zero.
     362         112 :       if (NumElems == 0)
     363           0 :         return ConstantExpr::getNullValue(DestTy);
     364             :       // Check for a struct with all members having the same size.
     365             :       Constant *MemberSize =
     366         224 :         getFoldedSizeOf(STy->getElementType(0), DestTy, true);
     367             :       bool AllSame = true;
     368         138 :       for (unsigned i = 1; i != NumElems; ++i)
     369          32 :         if (MemberSize !=
     370          64 :             getFoldedSizeOf(STy->getElementType(i), DestTy, true)) {
     371             :           AllSame = false;
     372             :           break;
     373             :         }
     374         112 :       if (AllSame) {
     375          93 :         Constant *N = ConstantInt::get(DestTy, NumElems);
     376          93 :         return ConstantExpr::getNUWMul(MemberSize, N);
     377             :       }
     378             :     }
     379             : 
     380             :   // Pointer size doesn't depend on the pointee type, so canonicalize them
     381             :   // to an arbitrary pointee.
     382             :   if (PointerType *PTy = dyn_cast<PointerType>(Ty))
     383          48 :     if (!PTy->getElementType()->isIntegerTy(1))
     384             :       return
     385          15 :         getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1),
     386             :                                          PTy->getAddressSpace()),
     387          15 :                         DestTy, true);
     388             : 
     389             :   // If there's no interesting folding happening, bail so that we don't create
     390             :   // a constant that looks like it needs folding but really doesn't.
     391         620 :   if (!Folded)
     392             :     return nullptr;
     393             : 
     394             :   // Base case: Get a regular sizeof expression.
     395         197 :   Constant *C = ConstantExpr::getSizeOf(Ty);
     396         197 :   C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
     397             :                                                     DestTy, false),
     398             :                             C, DestTy);
     399         197 :   return C;
     400             : }
     401             : 
     402             : /// Return a ConstantExpr with type DestTy for alignof on Ty, with any known
     403             : /// factors factored out. If Folded is false, return null if no factoring was
     404             : /// possible, to avoid endlessly bouncing an unfoldable expression back into the
     405             : /// top-level folder.
     406         106 : static Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, bool Folded) {
     407             :   // The alignment of an array is equal to the alignment of the
     408             :   // array element. Note that this is not always true for vectors.
     409             :   if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
     410          10 :     Constant *C = ConstantExpr::getAlignOf(ATy->getElementType());
     411          10 :     C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
     412             :                                                       DestTy,
     413             :                                                       false),
     414             :                               C, DestTy);
     415          10 :     return C;
     416             :   }
     417             : 
     418             :   if (StructType *STy = dyn_cast<StructType>(Ty)) {
     419             :     // Packed structs always have an alignment of 1.
     420          20 :     if (STy->isPacked())
     421          10 :       return ConstantInt::get(DestTy, 1);
     422             : 
     423             :     // Otherwise, struct alignment is the maximum alignment of any member.
     424             :     // Without target data, we can't compare much, but we can check to see
     425             :     // if all the members have the same alignment.
     426          10 :     unsigned NumElems = STy->getNumElements();
     427             :     // An empty struct has minimal alignment.
     428          10 :     if (NumElems == 0)
     429           0 :       return ConstantInt::get(DestTy, 1);
     430             :     // Check for a struct with all members having the same alignment.
     431             :     Constant *MemberAlign =
     432          20 :       getFoldedAlignOf(STy->getElementType(0), DestTy, true);
     433             :     bool AllSame = true;
     434          30 :     for (unsigned i = 1; i != NumElems; ++i)
     435          20 :       if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) {
     436             :         AllSame = false;
     437             :         break;
     438             :       }
     439          10 :     if (AllSame)
     440             :       return MemberAlign;
     441             :   }
     442             : 
     443             :   // Pointer alignment doesn't depend on the pointee type, so canonicalize them
     444             :   // to an arbitrary pointee.
     445             :   if (PointerType *PTy = dyn_cast<PointerType>(Ty))
     446          24 :     if (!PTy->getElementType()->isIntegerTy(1))
     447             :       return
     448           8 :         getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(),
     449             :                                                            1),
     450             :                                           PTy->getAddressSpace()),
     451           8 :                          DestTy, true);
     452             : 
     453             :   // If there's no interesting folding happening, bail so that we don't create
     454             :   // a constant that looks like it needs folding but really doesn't.
     455          68 :   if (!Folded)
     456             :     return nullptr;
     457             : 
     458             :   // Base case: Get a regular alignof expression.
     459          28 :   Constant *C = ConstantExpr::getAlignOf(Ty);
     460          28 :   C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
     461             :                                                     DestTy, false),
     462             :                             C, DestTy);
     463          28 :   return C;
     464             : }
     465             : 
     466             : /// Return a ConstantExpr with type DestTy for offsetof on Ty and FieldNo, with
     467             : /// any known factors factored out. If Folded is false, return null if no
     468             : /// factoring was possible, to avoid endlessly bouncing an unfoldable expression
     469             : /// back into the top-level folder.
     470          35 : static Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, Type *DestTy,
     471             :                                    bool Folded) {
     472             :   if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
     473          10 :     Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false,
     474             :                                                                 DestTy, false),
     475          10 :                                         FieldNo, DestTy);
     476          10 :     Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true);
     477          10 :     return ConstantExpr::getNUWMul(E, N);
     478             :   }
     479             : 
     480             :   if (StructType *STy = dyn_cast<StructType>(Ty))
     481          25 :     if (!STy->isPacked()) {
     482          25 :       unsigned NumElems = STy->getNumElements();
     483             :       // An empty struct has no members.
     484          25 :       if (NumElems == 0)
     485             :         return nullptr;
     486             :       // Check for a struct with all members having the same size.
     487             :       Constant *MemberSize =
     488          50 :         getFoldedSizeOf(STy->getElementType(0), DestTy, true);
     489             :       bool AllSame = true;
     490          85 :       for (unsigned i = 1; i != NumElems; ++i)
     491          45 :         if (MemberSize !=
     492          90 :             getFoldedSizeOf(STy->getElementType(i), DestTy, true)) {
     493             :           AllSame = false;
     494             :           break;
     495             :         }
     496          25 :       if (AllSame) {
     497          10 :         Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo,
     498             :                                                                     false,
     499             :                                                                     DestTy,
     500             :                                                                     false),
     501          10 :                                             FieldNo, DestTy);
     502          10 :         return ConstantExpr::getNUWMul(MemberSize, N);
     503             :       }
     504             :     }
     505             : 
     506             :   // If there's no interesting folding happening, bail so that we don't create
     507             :   // a constant that looks like it needs folding but really doesn't.
     508          15 :   if (!Folded)
     509             :     return nullptr;
     510             : 
     511             :   // Base case: Get a regular offsetof expression.
     512           0 :   Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo);
     513           0 :   C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
     514             :                                                     DestTy, false),
     515             :                             C, DestTy);
     516           0 :   return C;
     517             : }
     518             : 
     519     3102602 : Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
     520             :                                             Type *DestTy) {
     521     3102602 :   if (isa<UndefValue>(V)) {
     522             :     // zext(undef) = 0, because the top bits will be zero.
     523             :     // sext(undef) = 0, because the top bits will all be the same.
     524             :     // [us]itofp(undef) = 0, because the result value is bounded.
     525        8540 :     if (opc == Instruction::ZExt || opc == Instruction::SExt ||
     526        4505 :         opc == Instruction::UIToFP || opc == Instruction::SIToFP)
     527        4037 :       return Constant::getNullValue(DestTy);
     528         233 :     return UndefValue::get(DestTy);
     529             :   }
     530             : 
     531     3433819 :   if (V->isNullValue() && !DestTy->isX86_MMXTy() &&
     532             :       opc != Instruction::AddrSpaceCast)
     533      334979 :     return Constant::getNullValue(DestTy);
     534             : 
     535             :   // If the cast operand is a constant expression, there's a few things we can
     536             :   // do to try to simplify it.
     537             :   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
     538      791057 :     if (CE->isCast()) {
     539             :       // Try hard to fold cast of cast because they are often eliminable.
     540      532386 :       if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
     541      531515 :         return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
     542      511634 :     } else if (CE->getOpcode() == Instruction::GetElementPtr &&
     543             :                // Do not fold addrspacecast (gep 0, .., 0). It might make the
     544             :                // addrspacecast uncanonicalized.
     545      252883 :                opc != Instruction::AddrSpaceCast &&
     546             :                // Do not fold bitcast (gep) with inrange index, as this loses
     547             :                // information.
     548      738336 :                !cast<GEPOperator>(CE)->getInRangeIndex().hasValue() &&
     549             :                // Do not fold if the gep type is a vector, as bitcasting
     550             :                // operand 0 of a vector gep will result in a bitcast between
     551             :                // different sizes.
     552      226782 :                !CE->getType()->isVectorTy()) {
     553             :       // If all of the indexes in the GEP are null values, there is no pointer
     554             :       // adjustment going on.  We might as well cast the source pointer.
     555             :       bool isAllNull = true;
     556      999192 :       for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
     557      449189 :         if (!CE->getOperand(i)->isNullValue()) {
     558             :           isAllNull = false;
     559             :           break;
     560             :         }
     561      226778 :       if (isAllNull)
     562             :         // This is casting one pointer type to another, always BitCast
     563      163796 :         return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
     564             :     }
     565             :   }
     566             : 
     567             :   // If the cast operand is a constant vector, perform the cast by
     568             :   // operating on each element. In the cast of bitcasts, the element
     569             :   // count may be mismatched; don't attempt to handle that here.
     570     2068892 :   if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) &&
     571     2068945 :       DestTy->isVectorTy() &&
     572         903 :       DestTy->getVectorNumElements() == V->getType()->getVectorNumElements()) {
     573             :     SmallVector<Constant*, 16> res;
     574             :     VectorType *DestVecTy = cast<VectorType>(DestTy);
     575         722 :     Type *DstEltTy = DestVecTy->getElementType();
     576         722 :     Type *Ty = IntegerType::get(V->getContext(), 32);
     577        7894 :     for (unsigned i = 0, e = V->getType()->getVectorNumElements(); i != e; ++i) {
     578             :       Constant *C =
     579        3225 :         ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i));
     580        3225 :       res.push_back(ConstantExpr::getCast(opc, C, DstEltTy));
     581             :     }
     582         722 :     return ConstantVector::get(res);
     583             :   }
     584             : 
     585             :   // We actually have to do a cast now. Perform the cast according to the
     586             :   // opcode specified.
     587     2067320 :   switch (opc) {
     588           0 :   default:
     589           0 :     llvm_unreachable("Failed to cast constant expression");
     590        1795 :   case Instruction::FPTrunc:
     591             :   case Instruction::FPExt:
     592             :     if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
     593             :       bool ignored;
     594             :       APFloat Val = FPC->getValueAPF();
     595        1793 :       Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf() :
     596             :                   DestTy->isFloatTy() ? APFloat::IEEEsingle() :
     597             :                   DestTy->isDoubleTy() ? APFloat::IEEEdouble() :
     598             :                   DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended() :
     599             :                   DestTy->isFP128Ty() ? APFloat::IEEEquad() :
     600             :                   DestTy->isPPC_FP128Ty() ? APFloat::PPCDoubleDouble() :
     601             :                   APFloat::Bogus(),
     602             :                   APFloat::rmNearestTiesToEven, &ignored);
     603        1793 :       return ConstantFP::get(V->getContext(), Val);
     604             :     }
     605             :     return nullptr; // Can't fold.
     606          72 :   case Instruction::FPToUI:
     607             :   case Instruction::FPToSI:
     608             :     if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
     609             :       const APFloat &V = FPC->getValueAPF();
     610             :       bool ignored;
     611             :       uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     612          72 :       APSInt IntVal(DestBitWidth, opc == Instruction::FPToUI);
     613          72 :       if (APFloat::opInvalidOp ==
     614          72 :           V.convertToInteger(IntVal, APFloat::rmTowardZero, &ignored)) {
     615             :         // Undefined behavior invoked - the destination type can't represent
     616             :         // the input constant.
     617          18 :         return UndefValue::get(DestTy);
     618             :       }
     619          54 :       return ConstantInt::get(FPC->getContext(), IntVal);
     620             :     }
     621             :     return nullptr; // Can't fold.
     622       10617 :   case Instruction::IntToPtr:   //always treated as unsigned
     623       10617 :     if (V->isNullValue())       // Is it an integral null value?
     624           0 :       return ConstantPointerNull::get(cast<PointerType>(DestTy));
     625             :     return nullptr;                   // Other pointer types cannot be casted
     626       12677 :   case Instruction::PtrToInt:   // always treated as unsigned
     627             :     // Is it a null pointer value?
     628       12677 :     if (V->isNullValue())
     629           0 :       return ConstantInt::get(DestTy, 0);
     630             :     // If this is a sizeof-like expression, pull out multiplications by
     631             :     // known factors to expose them to subsequent folding. If it's an
     632             :     // alignof-like expression, factor out known factors.
     633             :     if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
     634        9415 :       if (CE->getOpcode() == Instruction::GetElementPtr &&
     635        4653 :           CE->getOperand(0)->isNullValue()) {
     636             :         // FIXME: Looks like getFoldedSizeOf(), getFoldedOffsetOf() and
     637             :         // getFoldedAlignOf() don't handle the case when DestTy is a vector of
     638             :         // pointers yet. We end up in asserts in CastInst::getCastOpcode (see
     639             :         // test/Analysis/ConstantFolding/cast-vector.ll). I've only seen this
     640             :         // happen in one "real" C-code test case, so it does not seem to be an
     641             :         // important optimization to handle vectors here. For now, simply bail
     642             :         // out.
     643         604 :         if (DestTy->isVectorTy())
     644             :           return nullptr;
     645             :         GEPOperator *GEPO = cast<GEPOperator>(CE);
     646         602 :         Type *Ty = GEPO->getSourceElementType();
     647         602 :         if (CE->getNumOperands() == 2) {
     648             :           // Handle a sizeof-like expression.
     649             :           Constant *Idx = CE->getOperand(1);
     650         978 :           bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne();
     651         489 :           if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) {
     652          66 :             Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true,
     653             :                                                                 DestTy, false),
     654             :                                         Idx, DestTy);
     655          66 :             return ConstantExpr::getMul(C, Idx);
     656             :           }
     657         226 :         } else if (CE->getNumOperands() == 3 &&
     658         113 :                    CE->getOperand(1)->isNullValue()) {
     659             :           // Handle an alignof-like expression.
     660             :           if (StructType *STy = dyn_cast<StructType>(Ty))
     661         103 :             if (!STy->isPacked()) {
     662             :               ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2));
     663          80 :               if (CI->isOne() &&
     664         182 :                   STy->getNumElements() == 2 &&
     665         158 :                   STy->getElementType(0)->isIntegerTy(1)) {
     666         156 :                 return getFoldedAlignOf(STy->getElementType(1), DestTy, false);
     667             :               }
     668             :             }
     669             :           // Handle an offsetof-like expression.
     670          35 :           if (Ty->isStructTy() || Ty->isArrayTy()) {
     671          35 :             if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2),
     672          35 :                                                 DestTy, false))
     673             :               return C;
     674             :           }
     675             :         }
     676             :       }
     677             :     // Other pointer types cannot be casted
     678             :     return nullptr;
     679        2718 :   case Instruction::UIToFP:
     680             :   case Instruction::SIToFP:
     681             :     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     682             :       const APInt &api = CI->getValue();
     683             :       APFloat apf(DestTy->getFltSemantics(),
     684        5410 :                   APInt::getNullValue(DestTy->getPrimitiveSizeInBits()));
     685        2705 :       apf.convertFromAPInt(api, opc==Instruction::SIToFP,
     686             :                            APFloat::rmNearestTiesToEven);
     687        2705 :       return ConstantFP::get(V->getContext(), apf);
     688             :     }
     689             :     return nullptr;
     690      122527 :   case Instruction::ZExt:
     691             :     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     692             :       uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     693      121095 :       return ConstantInt::get(V->getContext(),
     694      363285 :                               CI->getValue().zext(BitWidth));
     695             :     }
     696             :     return nullptr;
     697       92523 :   case Instruction::SExt:
     698             :     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     699             :       uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     700       92499 :       return ConstantInt::get(V->getContext(),
     701      277497 :                               CI->getValue().sext(BitWidth));
     702             :     }
     703             :     return nullptr;
     704      192992 :   case Instruction::Trunc: {
     705      385984 :     if (V->getType()->isVectorTy())
     706             :       return nullptr;
     707             : 
     708             :     uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     709             :     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     710      191800 :       return ConstantInt::get(V->getContext(),
     711      575400 :                               CI->getValue().trunc(DestBitWidth));
     712             :     }
     713             : 
     714             :     // The input must be a constantexpr.  See if we can simplify this based on
     715             :     // the bytes we are demanding.  Only do this if the source and dest are an
     716             :     // even multiple of a byte.
     717        2352 :     if ((DestBitWidth & 7) == 0 &&
     718             :         (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0)
     719        1163 :       if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8))
     720             :         return Res;
     721             : 
     722             :     return nullptr;
     723             :   }
     724     1629815 :   case Instruction::BitCast:
     725     1629815 :     return FoldBitCast(V, DestTy);
     726             :   case Instruction::AddrSpaceCast:
     727             :     return nullptr;
     728             :   }
     729             : }
     730             : 
     731        4825 : Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond,
     732             :                                               Constant *V1, Constant *V2) {
     733             :   // Check for i1 and vector true/false conditions.
     734        4825 :   if (Cond->isNullValue()) return V2;
     735        2855 :   if (Cond->isAllOnesValue()) return V1;
     736             : 
     737             :   // If the condition is a vector constant, fold the result elementwise.
     738             :   if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) {
     739             :     SmallVector<Constant*, 16> Result;
     740          73 :     Type *Ty = IntegerType::get(CondV->getContext(), 32);
     741         782 :     for (unsigned i = 0, e = V1->getType()->getVectorNumElements(); i != e;++i){
     742             :       Constant *V;
     743         319 :       Constant *V1Element = ConstantExpr::getExtractElement(V1,
     744             :                                                     ConstantInt::get(Ty, i));
     745         319 :       Constant *V2Element = ConstantExpr::getExtractElement(V2,
     746         319 :                                                     ConstantInt::get(Ty, i));
     747         319 :       Constant *Cond = dyn_cast<Constant>(CondV->getOperand(i));
     748         319 :       if (V1Element == V2Element) {
     749          78 :         V = V1Element;
     750         241 :       } else if (isa<UndefValue>(Cond)) {
     751           6 :         V = isa<UndefValue>(V1Element) ? V1Element : V2Element;
     752             :       } else {
     753         235 :         if (!isa<ConstantInt>(Cond)) break;
     754         234 :         V = Cond->isNullValue() ? V2Element : V1Element;
     755             :       }
     756         318 :       Result.push_back(V);
     757             :     }
     758             : 
     759             :     // If we were able to build the vector, return it.
     760         146 :     if (Result.size() == V1->getType()->getVectorNumElements())
     761          72 :       return ConstantVector::get(Result);
     762             :   }
     763             : 
     764         139 :   if (isa<UndefValue>(Cond)) {
     765          28 :     if (isa<UndefValue>(V1)) return V1;
     766          16 :     return V2;
     767             :   }
     768         111 :   if (isa<UndefValue>(V1)) return V2;
     769         111 :   if (isa<UndefValue>(V2)) return V1;
     770         110 :   if (V1 == V2) return V1;
     771             : 
     772          64 :   if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) {
     773          64 :     if (TrueVal->getOpcode() == Instruction::Select)
     774           1 :       if (TrueVal->getOperand(0) == Cond)
     775           1 :         return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2);
     776             :   }
     777          18 :   if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) {
     778          18 :     if (FalseVal->getOpcode() == Instruction::Select)
     779           0 :       if (FalseVal->getOperand(0) == Cond)
     780           0 :         return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2));
     781             :   }
     782             : 
     783             :   return nullptr;
     784             : }
     785             : 
     786      309971 : Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val,
     787             :                                                       Constant *Idx) {
     788      309971 :   if (isa<UndefValue>(Val))  // ee(undef, x) -> undef
     789      190072 :     return UndefValue::get(Val->getType()->getVectorElementType());
     790      214935 :   if (Val->isNullValue())  // ee(zero, x) -> zero
     791        6578 :     return Constant::getNullValue(Val->getType()->getVectorElementType());
     792             :   // ee({w,x,y,z}, undef) -> undef
     793      211646 :   if (isa<UndefValue>(Idx))
     794           2 :     return UndefValue::get(Val->getType()->getVectorElementType());
     795             : 
     796             :   if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
     797             :     // ee({w,x,y,z}, wrong_value) -> undef
     798      423290 :     if (CIdx->uge(Val->getType()->getVectorNumElements()))
     799           6 :       return UndefValue::get(Val->getType()->getVectorElementType());
     800      211642 :     return Val->getAggregateElement(CIdx->getZExtValue());
     801             :   }
     802             :   return nullptr;
     803             : }
     804             : 
     805      157772 : Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val,
     806             :                                                      Constant *Elt,
     807             :                                                      Constant *Idx) {
     808      157772 :   if (isa<UndefValue>(Idx))
     809           1 :     return UndefValue::get(Val->getType());
     810             : 
     811             :   ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
     812             :   if (!CIdx) return nullptr;
     813             : 
     814      157771 :   unsigned NumElts = Val->getType()->getVectorNumElements();
     815      157771 :   if (CIdx->uge(NumElts))
     816           3 :     return UndefValue::get(Val->getType());
     817             : 
     818             :   SmallVector<Constant*, 16> Result;
     819      157768 :   Result.reserve(NumElts);
     820      157768 :   auto *Ty = Type::getInt32Ty(Val->getContext());
     821             :   uint64_t IdxVal = CIdx->getZExtValue();
     822      999366 :   for (unsigned i = 0; i != NumElts; ++i) {
     823      578567 :     if (i == IdxVal) {
     824      157768 :       Result.push_back(Elt);
     825      157768 :       continue;
     826             :     }
     827             : 
     828      263031 :     Constant *C = ConstantExpr::getExtractElement(Val, ConstantInt::get(Ty, i));
     829      263031 :     Result.push_back(C);
     830             :   }
     831             : 
     832      157768 :   return ConstantVector::get(Result);
     833             : }
     834             : 
     835        3299 : Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1,
     836             :                                                      Constant *V2,
     837             :                                                      Constant *Mask) {
     838        3299 :   unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
     839        3299 :   Type *EltTy = V1->getType()->getVectorElementType();
     840             : 
     841             :   // Undefined shuffle mask -> undefined value.
     842        3299 :   if (isa<UndefValue>(Mask))
     843          13 :     return UndefValue::get(VectorType::get(EltTy, MaskNumElts));
     844             : 
     845             :   // Don't break the bitcode reader hack.
     846        3286 :   if (isa<ConstantExpr>(Mask)) return nullptr;
     847             : 
     848             :   unsigned SrcNumElts = V1->getType()->getVectorNumElements();
     849             : 
     850             :   // Loop over the shuffle mask, evaluating each element.
     851             :   SmallVector<Constant*, 32> Result;
     852       40234 :   for (unsigned i = 0; i != MaskNumElts; ++i) {
     853       18474 :     int Elt = ShuffleVectorInst::getMaskValue(Mask, i);
     854       18768 :     if (Elt == -1) {
     855         294 :       Result.push_back(UndefValue::get(EltTy));
     856         294 :       continue;
     857             :     }
     858             :     Constant *InElt;
     859       18180 :     if (unsigned(Elt) >= SrcNumElts*2)
     860           0 :       InElt = UndefValue::get(EltTy);
     861       18180 :     else if (unsigned(Elt) >= SrcNumElts) {
     862         697 :       Type *Ty = IntegerType::get(V2->getContext(), 32);
     863         697 :       InElt =
     864         697 :         ConstantExpr::getExtractElement(V2,
     865         697 :                                         ConstantInt::get(Ty, Elt - SrcNumElts));
     866             :     } else {
     867       17483 :       Type *Ty = IntegerType::get(V1->getContext(), 32);
     868       17483 :       InElt = ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, Elt));
     869             :     }
     870       18180 :     Result.push_back(InElt);
     871             :   }
     872             : 
     873        3286 :   return ConstantVector::get(Result);
     874             : }
     875             : 
     876      328929 : Constant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg,
     877             :                                                     ArrayRef<unsigned> Idxs) {
     878             :   // Base case: no indices, so return the entire value.
     879      328929 :   if (Idxs.empty())
     880             :     return Agg;
     881             : 
     882      164473 :   if (Constant *C = Agg->getAggregateElement(Idxs[0]))
     883      164468 :     return ConstantFoldExtractValueInstruction(C, Idxs.slice(1));
     884             : 
     885             :   return nullptr;
     886             : }
     887             : 
     888         584 : Constant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg,
     889             :                                                    Constant *Val,
     890             :                                                    ArrayRef<unsigned> Idxs) {
     891             :   // Base case: no indices, so replace the entire value.
     892         584 :   if (Idxs.empty())
     893             :     return Val;
     894             : 
     895             :   unsigned NumElts;
     896         354 :   if (StructType *ST = dyn_cast<StructType>(Agg->getType()))
     897         242 :     NumElts = ST->getNumElements();
     898             :   else
     899         112 :     NumElts = cast<SequentialType>(Agg->getType())->getNumElements();
     900             : 
     901             :   SmallVector<Constant*, 32> Result;
     902       10354 :   for (unsigned i = 0; i != NumElts; ++i) {
     903        5001 :     Constant *C = Agg->getAggregateElement(i);
     904        5001 :     if (!C) return nullptr;
     905             : 
     906        5000 :     if (Idxs[0] == i)
     907         353 :       C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1));
     908             : 
     909        5000 :     Result.push_back(C);
     910             :   }
     911             : 
     912         353 :   if (StructType *ST = dyn_cast<StructType>(Agg->getType()))
     913         241 :     return ConstantStruct::get(ST, Result);
     914             :   if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType()))
     915         112 :     return ConstantArray::get(AT, Result);
     916           0 :   return ConstantVector::get(Result);
     917             : }
     918             : 
     919             : 
     920      798564 : Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
     921             :                                               Constant *C1, Constant *C2) {
     922             :   assert(Instruction::isBinaryOp(Opcode) && "Non-binary instruction detected");
     923             : 
     924             :   // Handle UndefValue up front.
     925     1596629 :   if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
     926         784 :     switch (static_cast<Instruction::BinaryOps>(Opcode)) {
     927          34 :     case Instruction::Xor:
     928          53 :       if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
     929             :         // Handle undef ^ undef -> 0 special case. This is a common
     930             :         // idiom (misuse).
     931           3 :         return Constant::getNullValue(C1->getType());
     932             :       LLVM_FALLTHROUGH;
     933             :     case Instruction::Add:
     934             :     case Instruction::Sub:
     935         176 :       return UndefValue::get(C1->getType());
     936         121 :     case Instruction::And:
     937         241 :       if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef
     938             :         return C1;
     939         115 :       return Constant::getNullValue(C1->getType());   // undef & X -> 0
     940          13 :     case Instruction::Mul: {
     941             :       // undef * undef -> undef
     942          19 :       if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
     943             :         return C1;
     944             :       const APInt *CV;
     945             :       // X * undef -> undef   if X is odd
     946          26 :       if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV)))
     947          22 :         if ((*CV)[0])
     948           3 :           return UndefValue::get(C1->getType());
     949             : 
     950             :       // X * undef -> 0       otherwise
     951           8 :       return Constant::getNullValue(C1->getType());
     952             :     }
     953           8 :     case Instruction::SDiv:
     954             :     case Instruction::UDiv:
     955             :       // X / undef -> undef
     956           8 :       if (isa<UndefValue>(C2))
     957             :         return C2;
     958             :       // undef / 0 -> undef
     959             :       // undef / 1 -> undef
     960          14 :       if (match(C2, m_Zero()) || match(C2, m_One()))
     961             :         return C1;
     962             :       // undef / X -> 0       otherwise
     963           3 :       return Constant::getNullValue(C1->getType());
     964             :     case Instruction::URem:
     965             :     case Instruction::SRem:
     966             :       // X % undef -> undef
     967          12 :       if (match(C2, m_Undef()))
     968             :         return C2;
     969             :       // undef % 0 -> undef
     970          12 :       if (match(C2, m_Zero()))
     971             :         return C1;
     972             :       // undef % X -> 0       otherwise
     973          12 :       return Constant::getNullValue(C1->getType());
     974          20 :     case Instruction::Or:                          // X | undef -> -1
     975          33 :       if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef
     976             :         return C1;
     977           9 :       return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0
     978          29 :     case Instruction::LShr:
     979             :       // X >>l undef -> undef
     980          29 :       if (isa<UndefValue>(C2))
     981             :         return C2;
     982             :       // undef >>l 0 -> undef
     983          26 :       if (match(C2, m_Zero()))
     984             :         return C1;
     985             :       // undef >>l X -> 0
     986          25 :       return Constant::getNullValue(C1->getType());
     987           9 :     case Instruction::AShr:
     988             :       // X >>a undef -> undef
     989           9 :       if (isa<UndefValue>(C2))
     990             :         return C2;
     991             :       // undef >>a 0 -> undef
     992           7 :       if (match(C2, m_Zero()))
     993             :         return C1;
     994             :       // TODO: undef >>a X -> undef if the shift is exact
     995             :       // undef >>a X -> 0
     996           6 :       return Constant::getNullValue(C1->getType());
     997          31 :     case Instruction::Shl:
     998             :       // X << undef -> undef
     999          31 :       if (isa<UndefValue>(C2))
    1000             :         return C2;
    1001             :       // undef << 0 -> undef
    1002          25 :       if (match(C2, m_Zero()))
    1003             :         return C1;
    1004             :       // undef << X -> 0
    1005          23 :       return Constant::getNullValue(C1->getType());
    1006         362 :     case Instruction::FAdd:
    1007             :     case Instruction::FSub:
    1008             :     case Instruction::FMul:
    1009             :     case Instruction::FDiv:
    1010             :     case Instruction::FRem:
    1011             :       // [any flop] undef, undef -> undef
    1012         529 :       if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
    1013             :         return C1;
    1014             :       // [any flop] C, undef -> NaN
    1015             :       // [any flop] undef, C -> NaN
    1016             :       // We could potentially specialize NaN/Inf constants vs. 'normal'
    1017             :       // constants (possibly differently depending on opcode and operand). This
    1018             :       // would allow returning undef sometimes. But it is always safe to fold to
    1019             :       // NaN because we can choose the undef operand as NaN, and any FP opcode
    1020             :       // with a NaN operand will propagate NaN.
    1021         291 :       return ConstantFP::getNaN(C1->getType());
    1022           0 :     case Instruction::BinaryOpsEnd:
    1023           0 :       llvm_unreachable("Invalid BinaryOp");
    1024             :     }
    1025             :   }
    1026             : 
    1027             :   // At this point neither constant should be an UndefValue.
    1028             :   assert(!isa<UndefValue>(C1) && !isa<UndefValue>(C2) &&
    1029             :          "Unexpected UndefValue");
    1030             : 
    1031             :   // Handle simplifications when the RHS is a constant int.
    1032             :   if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
    1033      787356 :     switch (Opcode) {
    1034             :     case Instruction::Add:
    1035      160532 :       if (CI2->isZero()) return C1;                             // X + 0 == X
    1036             :       break;
    1037             :     case Instruction::Sub:
    1038      445957 :       if (CI2->isZero()) return C1;                             // X - 0 == X
    1039             :       break;
    1040             :     case Instruction::Mul:
    1041       19897 :       if (CI2->isZero()) return C2;                             // X * 0 == 0
    1042       19592 :       if (CI2->isOne())
    1043             :         return C1;                                              // X * 1 == X
    1044             :       break;
    1045             :     case Instruction::UDiv:
    1046             :     case Instruction::SDiv:
    1047       29743 :       if (CI2->isOne())
    1048             :         return C1;                                            // X / 1 == X
    1049       12865 :       if (CI2->isZero())
    1050           6 :         return UndefValue::get(CI2->getType());               // X / 0 == undef
    1051             :       break;
    1052             :     case Instruction::URem:
    1053             :     case Instruction::SRem:
    1054         920 :       if (CI2->isOne())
    1055          14 :         return Constant::getNullValue(CI2->getType());        // X % 1 == 0
    1056         906 :       if (CI2->isZero())
    1057           3 :         return UndefValue::get(CI2->getType());               // X % 0 == undef
    1058             :       break;
    1059             :     case Instruction::And:
    1060       15418 :       if (CI2->isZero()) return C2;                           // X & 0 == 0
    1061       15352 :       if (CI2->isMinusOne())
    1062             :         return C1;                                            // X & -1 == X
    1063             : 
    1064             :       if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
    1065             :         // (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
    1066        3138 :         if (CE1->getOpcode() == Instruction::ZExt) {
    1067             :           unsigned DstWidth = CI2->getType()->getBitWidth();
    1068             :           unsigned SrcWidth =
    1069           3 :             CE1->getOperand(0)->getType()->getPrimitiveSizeInBits();
    1070           3 :           APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth));
    1071           6 :           if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits)
    1072             :             return C1;
    1073             :         }
    1074             : 
    1075             :         // If and'ing the address of a global with a constant, fold it.
    1076        3138 :         if (CE1->getOpcode() == Instruction::PtrToInt &&
    1077             :             isa<GlobalValue>(CE1->getOperand(0))) {
    1078             :           GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0));
    1079             : 
    1080             :           // Functions are at least 4-byte aligned.
    1081         137 :           unsigned GVAlign = GV->getAlignment();
    1082         137 :           if (isa<Function>(GV))
    1083         128 :             GVAlign = std::max(GVAlign, 4U);
    1084             : 
    1085         137 :           if (GVAlign > 1) {
    1086         112 :             unsigned DstWidth = CI2->getType()->getBitWidth();
    1087         224 :             unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign));
    1088         112 :             APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth));
    1089             : 
    1090             :             // If checking bits we know are clear, return zero.
    1091         224 :             if ((CI2->getValue() & BitsNotSet) == CI2->getValue())
    1092          83 :               return Constant::getNullValue(CI2->getType());
    1093             :           }
    1094             :         }
    1095             :       }
    1096             :       break;
    1097             :     case Instruction::Or:
    1098        8999 :       if (CI2->isZero()) return C1;        // X | 0 == X
    1099        8396 :       if (CI2->isMinusOne())
    1100             :         return C2;                         // X | -1 == -1
    1101             :       break;
    1102             :     case Instruction::Xor:
    1103       85339 :       if (CI2->isZero()) return C1;        // X ^ 0 == X
    1104             : 
    1105             :       if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
    1106          62 :         switch (CE1->getOpcode()) {
    1107             :         default: break;
    1108          29 :         case Instruction::ICmp:
    1109             :         case Instruction::FCmp:
    1110             :           // cmp pred ^ true -> cmp !pred
    1111             :           assert(CI2->isOne());
    1112          29 :           CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate();
    1113          29 :           pred = CmpInst::getInversePredicate(pred);
    1114          29 :           return ConstantExpr::getCompare(pred, CE1->getOperand(0),
    1115          29 :                                           CE1->getOperand(1));
    1116             :         }
    1117             :       }
    1118             :       break;
    1119        1432 :     case Instruction::AShr:
    1120             :       // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
    1121             :       if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1))
    1122          47 :         if (CE1->getOpcode() == Instruction::ZExt)  // Top bits known zero.
    1123           0 :           return ConstantExpr::getLShr(C1, C2);
    1124             :       break;
    1125             :     }
    1126       10424 :   } else if (isa<ConstantInt>(C1)) {
    1127             :     // If C1 is a ConstantInt and C2 is not, swap the operands.
    1128             :     if (Instruction::isCommutative(Opcode))
    1129        1070 :       return ConstantExpr::get(Opcode, C2, C1);
    1130             :   }
    1131             : 
    1132             :   if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
    1133             :     if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
    1134             :       const APInt &C1V = CI1->getValue();
    1135             :       const APInt &C2V = CI2->getValue();
    1136      547094 :       switch (Opcode) {
    1137             :       default:
    1138             :         break;
    1139             :       case Instruction::Add:
    1140      471519 :         return ConstantInt::get(CI1->getContext(), C1V + C2V);
    1141             :       case Instruction::Sub:
    1142      724584 :         return ConstantInt::get(CI1->getContext(), C1V - C2V);
    1143        8785 :       case Instruction::Mul:
    1144       17570 :         return ConstantInt::get(CI1->getContext(), C1V * C2V);
    1145       11247 :       case Instruction::UDiv:
    1146             :         assert(!CI2->isZero() && "Div by zero handled above");
    1147       22494 :         return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V));
    1148             :       case Instruction::SDiv:
    1149             :         assert(!CI2->isZero() && "Div by zero handled above");
    1150        1579 :         if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
    1151           1 :           return UndefValue::get(CI1->getType());   // MIN_INT / -1 -> undef
    1152        3156 :         return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V));
    1153         765 :       case Instruction::URem:
    1154             :         assert(!CI2->isZero() && "Div by zero handled above");
    1155        1530 :         return ConstantInt::get(CI1->getContext(), C1V.urem(C2V));
    1156             :       case Instruction::SRem:
    1157             :         assert(!CI2->isZero() && "Div by zero handled above");
    1158         130 :         if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
    1159           1 :           return UndefValue::get(CI1->getType());   // MIN_INT % -1 -> undef
    1160         258 :         return ConstantInt::get(CI1->getContext(), C1V.srem(C2V));
    1161             :       case Instruction::And:
    1162       36510 :         return ConstantInt::get(CI1->getContext(), C1V & C2V);
    1163             :       case Instruction::Or:
    1164       24897 :         return ConstantInt::get(CI1->getContext(), C1V | C2V);
    1165             :       case Instruction::Xor:
    1166      255384 :         return ConstantInt::get(CI1->getContext(), C1V ^ C2V);
    1167       16225 :       case Instruction::Shl:
    1168       16225 :         if (C2V.ult(C1V.getBitWidth()))
    1169       32412 :           return ConstantInt::get(CI1->getContext(), C1V.shl(C2V));
    1170          19 :         return UndefValue::get(C1->getType()); // too big shift is undef
    1171        2680 :       case Instruction::LShr:
    1172        2680 :         if (C2V.ult(C1V.getBitWidth()))
    1173        5320 :           return ConstantInt::get(CI1->getContext(), C1V.lshr(C2V));
    1174          20 :         return UndefValue::get(C1->getType()); // too big shift is undef
    1175        1385 :       case Instruction::AShr:
    1176        1385 :         if (C2V.ult(C1V.getBitWidth()))
    1177        2750 :           return ConstantInt::get(CI1->getContext(), C1V.ashr(C2V));
    1178          10 :         return UndefValue::get(C1->getType()); // too big shift is undef
    1179             :       }
    1180             :     }
    1181             : 
    1182             :     switch (Opcode) {
    1183             :     case Instruction::SDiv:
    1184             :     case Instruction::UDiv:
    1185             :     case Instruction::URem:
    1186             :     case Instruction::SRem:
    1187             :     case Instruction::LShr:
    1188             :     case Instruction::AShr:
    1189             :     case Instruction::Shl:
    1190          64 :       if (CI1->isZero()) return C1;
    1191             :       break;
    1192             :     default:
    1193             :       break;
    1194             :     }
    1195             :   } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
    1196             :     if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
    1197             :       const APFloat &C1V = CFP1->getValueAPF();
    1198             :       const APFloat &C2V = CFP2->getValueAPF();
    1199             :       APFloat C3V = C1V;  // copy for modification
    1200        1011 :       switch (Opcode) {
    1201             :       default:
    1202             :         break;
    1203         303 :       case Instruction::FAdd:
    1204         303 :         (void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
    1205         303 :         return ConstantFP::get(C1->getContext(), C3V);
    1206         271 :       case Instruction::FSub:
    1207         271 :         (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
    1208         271 :         return ConstantFP::get(C1->getContext(), C3V);
    1209         283 :       case Instruction::FMul:
    1210         283 :         (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
    1211         283 :         return ConstantFP::get(C1->getContext(), C3V);
    1212          93 :       case Instruction::FDiv:
    1213          93 :         (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
    1214          93 :         return ConstantFP::get(C1->getContext(), C3V);
    1215          61 :       case Instruction::FRem:
    1216          61 :         (void)C3V.mod(C2V);
    1217          61 :         return ConstantFP::get(C1->getContext(), C3V);
    1218             :       }
    1219             :     }
    1220       13220 :   } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) {
    1221             :     // Perform elementwise folding.
    1222             :     SmallVector<Constant*, 16> Result;
    1223        2868 :     Type *Ty = IntegerType::get(VTy->getContext(), 32);
    1224       14766 :     for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
    1225       11903 :       Constant *ExtractIdx = ConstantInt::get(Ty, i);
    1226       11903 :       Constant *LHS = ConstantExpr::getExtractElement(C1, ExtractIdx);
    1227       11903 :       Constant *RHS = ConstantExpr::getExtractElement(C2, ExtractIdx);
    1228             : 
    1229             :       // If any element of a divisor vector is zero, the whole op is undef.
    1230          35 :       if (Instruction::isIntDivRem(Opcode) && RHS->isNullValue())
    1231           5 :         return UndefValue::get(VTy);
    1232             : 
    1233       11898 :       Result.push_back(ConstantExpr::get(Opcode, LHS, RHS));
    1234             :     }
    1235             : 
    1236        2863 :     return ConstantVector::get(Result);
    1237             :   }
    1238             : 
    1239             :   if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
    1240             :     // There are many possible foldings we could do here.  We should probably
    1241             :     // at least fold add of a pointer with an integer into the appropriate
    1242             :     // getelementptr.  This will improve alias analysis a bit.
    1243             : 
    1244             :     // Given ((a + b) + c), if (b + c) folds to something interesting, return
    1245             :     // (a + (b + c)).
    1246        8696 :     if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) {
    1247          62 :       Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2);
    1248          77 :       if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode)
    1249          47 :         return ConstantExpr::get(Opcode, CE1->getOperand(0), T);
    1250             :     }
    1251         130 :   } else if (isa<ConstantExpr>(C2)) {
    1252             :     // If C2 is a constant expr and C1 isn't, flop them around and fold the
    1253             :     // other way if possible.
    1254             :     if (Instruction::isCommutative(Opcode))
    1255           0 :       return ConstantFoldBinaryInstruction(Opcode, C2, C1);
    1256             :   }
    1257             : 
    1258             :   // i1 can be simplified in many cases.
    1259       10435 :   if (C1->getType()->isIntegerTy(1)) {
    1260         700 :     switch (Opcode) {
    1261           2 :     case Instruction::Add:
    1262             :     case Instruction::Sub:
    1263           2 :       return ConstantExpr::getXor(C1, C2);
    1264           1 :     case Instruction::Mul:
    1265           1 :       return ConstantExpr::getAnd(C1, C2);
    1266             :     case Instruction::Shl:
    1267             :     case Instruction::LShr:
    1268             :     case Instruction::AShr:
    1269             :       // We can assume that C2 == 0.  If it were one the result would be
    1270             :       // undefined because the shift value is as large as the bitwidth.
    1271             :       return C1;
    1272             :     case Instruction::SDiv:
    1273             :     case Instruction::UDiv:
    1274             :       // We can assume that C2 == 1.  If it were zero the result would be
    1275             :       // undefined through division by zero.
    1276             :       return C1;
    1277           2 :     case Instruction::URem:
    1278             :     case Instruction::SRem:
    1279             :       // We can assume that C2 == 1.  If it were zero the result would be
    1280             :       // undefined through division by zero.
    1281           2 :       return ConstantInt::getFalse(C1->getContext());
    1282             :     default:
    1283             :       break;
    1284             :     }
    1285             :   }
    1286             : 
    1287             :   // We don't know how to fold this.
    1288       10428 :   return nullptr;
    1289             : }
    1290             : 
    1291             : /// This type is zero-sized if it's an array or structure of zero-sized types.
    1292             : /// The only leaf zero-sized type is an empty structure.
    1293          15 : static bool isMaybeZeroSizedType(Type *Ty) {
    1294             :   if (StructType *STy = dyn_cast<StructType>(Ty)) {
    1295           8 :     if (STy->isOpaque()) return true;  // Can't say.
    1296             : 
    1297             :     // If all of elements have zero size, this does too.
    1298           8 :     for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
    1299          16 :       if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
    1300             :     return true;
    1301             : 
    1302             :   } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
    1303           4 :     return isMaybeZeroSizedType(ATy->getElementType());
    1304             :   }
    1305             :   return false;
    1306             : }
    1307             : 
    1308             : /// Compare the two constants as though they were getelementptr indices.
    1309             : /// This allows coercion of the types to be the same thing.
    1310             : ///
    1311             : /// If the two constants are the "same" (after coercion), return 0.  If the
    1312             : /// first is less than the second, return -1, if the second is less than the
    1313             : /// first, return 1.  If the constants are not integral, return -2.
    1314             : ///
    1315          18 : static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) {
    1316          18 :   if (C1 == C2) return 0;
    1317             : 
    1318             :   // Ok, we found a different index.  If they are not ConstantInt, we can't do
    1319             :   // anything with them.
    1320          15 :   if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
    1321             :     return -2; // don't know!
    1322             : 
    1323             :   // We cannot compare the indices if they don't fit in an int64_t.
    1324          14 :   if (cast<ConstantInt>(C1)->getValue().getActiveBits() > 64 ||
    1325             :       cast<ConstantInt>(C2)->getValue().getActiveBits() > 64)
    1326             :     return -2; // don't know!
    1327             : 
    1328             :   // Ok, we have two differing integer indices.  Sign extend them to be the same
    1329             :   // type.
    1330             :   int64_t C1Val = cast<ConstantInt>(C1)->getSExtValue();
    1331             :   int64_t C2Val = cast<ConstantInt>(C2)->getSExtValue();
    1332             : 
    1333           7 :   if (C1Val == C2Val) return 0;  // They are equal
    1334             : 
    1335             :   // If the type being indexed over is really just a zero sized type, there is
    1336             :   // no pointer difference being made here.
    1337           7 :   if (isMaybeZeroSizedType(ElTy))
    1338             :     return -2; // dunno.
    1339             : 
    1340             :   // If they are really different, now that they are the same type, then we
    1341             :   // found a difference!
    1342           7 :   if (C1Val < C2Val)
    1343             :     return -1;
    1344             :   else
    1345           0 :     return 1;
    1346             : }
    1347             : 
    1348             : /// This function determines if there is anything we can decide about the two
    1349             : /// constants provided. This doesn't need to handle simple things like
    1350             : /// ConstantFP comparisons, but should instead handle ConstantExprs.
    1351             : /// If we can determine that the two constants have a particular relation to
    1352             : /// each other, we should return the corresponding FCmpInst predicate,
    1353             : /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
    1354             : /// ConstantFoldCompareInstruction.
    1355             : ///
    1356             : /// To simplify this code we canonicalize the relation so that the first
    1357             : /// operand is always the most "complex" of the two.  We consider ConstantFP
    1358             : /// to be the simplest, and ConstantExprs to be the most complex.
    1359           4 : static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) {
    1360             :   assert(V1->getType() == V2->getType() &&
    1361             :          "Cannot compare values of different types!");
    1362             : 
    1363             :   // Handle degenerate case quickly
    1364           4 :   if (V1 == V2) return FCmpInst::FCMP_OEQ;
    1365             : 
    1366           4 :   if (!isa<ConstantExpr>(V1)) {
    1367           0 :     if (!isa<ConstantExpr>(V2)) {
    1368             :       // Simple case, use the standard constant folder.
    1369             :       ConstantInt *R = nullptr;
    1370           0 :       R = dyn_cast<ConstantInt>(
    1371             :                       ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2));
    1372           0 :       if (R && !R->isZero())
    1373             :         return FCmpInst::FCMP_OEQ;
    1374           0 :       R = dyn_cast<ConstantInt>(
    1375             :                       ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2));
    1376           0 :       if (R && !R->isZero())
    1377             :         return FCmpInst::FCMP_OLT;
    1378           0 :       R = dyn_cast<ConstantInt>(
    1379             :                       ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2));
    1380           0 :       if (R && !R->isZero())
    1381             :         return FCmpInst::FCMP_OGT;
    1382             : 
    1383             :       // Nothing more we can do
    1384             :       return FCmpInst::BAD_FCMP_PREDICATE;
    1385             :     }
    1386             : 
    1387             :     // If the first operand is simple and second is ConstantExpr, swap operands.
    1388           0 :     FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
    1389           0 :     if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
    1390           0 :       return FCmpInst::getSwappedPredicate(SwappedRelation);
    1391             :   } else {
    1392             :     // Ok, the LHS is known to be a constantexpr.  The RHS can be any of a
    1393             :     // constantexpr or a simple constant.
    1394             :     ConstantExpr *CE1 = cast<ConstantExpr>(V1);
    1395             :     switch (CE1->getOpcode()) {
    1396             :     case Instruction::FPTrunc:
    1397             :     case Instruction::FPExt:
    1398             :     case Instruction::UIToFP:
    1399             :     case Instruction::SIToFP:
    1400             :       // We might be able to do something with these but we don't right now.
    1401             :       break;
    1402             :     default:
    1403             :       break;
    1404             :     }
    1405             :   }
    1406             :   // There are MANY other foldings that we could perform here.  They will
    1407             :   // probably be added on demand, as they seem needed.
    1408             :   return FCmpInst::BAD_FCMP_PREDICATE;
    1409             : }
    1410             : 
    1411          95 : static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1,
    1412             :                                                       const GlobalValue *GV2) {
    1413         146 :   auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) {
    1414         146 :     if (GV->hasExternalWeakLinkage() || GV->hasWeakAnyLinkage())
    1415             :       return true;
    1416             :     if (const auto *GVar = dyn_cast<GlobalVariable>(GV)) {
    1417         105 :       Type *Ty = GVar->getValueType();
    1418             :       // A global with opaque type might end up being zero sized.
    1419         105 :       if (!Ty->isSized())
    1420             :         return true;
    1421             :       // A global with an empty type might lie at the address of any other
    1422             :       // global.
    1423         105 :       if (Ty->isEmptyTy())
    1424             :         return true;
    1425             :     }
    1426             :     return false;
    1427             :   };
    1428             :   // Don't try to decide equality of aliases.
    1429         190 :   if (!isa<GlobalAlias>(GV1) && !isa<GlobalAlias>(GV2))
    1430          95 :     if (!isGlobalUnsafeForEquality(GV1) && !isGlobalUnsafeForEquality(GV2))
    1431             :       return ICmpInst::ICMP_NE;
    1432             :   return ICmpInst::BAD_ICMP_PREDICATE;
    1433             : }
    1434             : 
    1435             : /// This function determines if there is anything we can decide about the two
    1436             : /// constants provided. This doesn't need to handle simple things like integer
    1437             : /// comparisons, but should instead handle ConstantExprs and GlobalValues.
    1438             : /// If we can determine that the two constants have a particular relation to
    1439             : /// each other, we should return the corresponding ICmp predicate, otherwise
    1440             : /// return ICmpInst::BAD_ICMP_PREDICATE.
    1441             : ///
    1442             : /// To simplify this code we canonicalize the relation so that the first
    1443             : /// operand is always the most "complex" of the two.  We consider simple
    1444             : /// constants (like ConstantInt) to be the simplest, followed by
    1445             : /// GlobalValues, followed by ConstantExpr's (the most complex).
    1446             : ///
    1447       18855 : static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2,
    1448             :                                                 bool isSigned) {
    1449             :   assert(V1->getType() == V2->getType() &&
    1450             :          "Cannot compare different types of values!");
    1451       18855 :   if (V1 == V2) return ICmpInst::ICMP_EQ;
    1452             : 
    1453        7083 :   if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) &&
    1454             :       !isa<BlockAddress>(V1)) {
    1455          12 :     if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) &&
    1456             :         !isa<BlockAddress>(V2)) {
    1457             :       // We distilled this down to a simple case, use the standard constant
    1458             :       // folder.
    1459             :       ConstantInt *R = nullptr;
    1460             :       ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
    1461           1 :       R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
    1462           0 :       if (R && !R->isZero())
    1463             :         return pred;
    1464           1 :       pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
    1465           1 :       R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
    1466           0 :       if (R && !R->isZero())
    1467             :         return pred;
    1468           1 :       pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
    1469           1 :       R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
    1470           0 :       if (R && !R->isZero())
    1471             :         return pred;
    1472             : 
    1473             :       // If we couldn't figure it out, bail.
    1474             :       return ICmpInst::BAD_ICMP_PREDICATE;
    1475             :     }
    1476             : 
    1477             :     // If the first operand is simple, swap operands.
    1478             :     ICmpInst::Predicate SwappedRelation =
    1479          15 :       evaluateICmpRelation(V2, V1, isSigned);
    1480          15 :     if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
    1481           0 :       return ICmpInst::getSwappedPredicate(SwappedRelation);
    1482             : 
    1483             :   } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) {
    1484         571 :     if (isa<ConstantExpr>(V2)) {  // Swap as necessary.
    1485             :       ICmpInst::Predicate SwappedRelation =
    1486           4 :         evaluateICmpRelation(V2, V1, isSigned);
    1487           4 :       if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
    1488           4 :         return ICmpInst::getSwappedPredicate(SwappedRelation);
    1489             :       return ICmpInst::BAD_ICMP_PREDICATE;
    1490             :     }
    1491             : 
    1492             :     // Now we know that the RHS is a GlobalValue, BlockAddress or simple
    1493             :     // constant (which, since the types must match, means that it's a
    1494             :     // ConstantPointerNull).
    1495             :     if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) {
    1496          82 :       return areGlobalsPotentiallyEqual(GV, GV2);
    1497         485 :     } else if (isa<BlockAddress>(V2)) {
    1498             :       return ICmpInst::ICMP_NE; // Globals never equal labels.
    1499             :     } else {
    1500             :       assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
    1501             :       // GlobalVals can never be null unless they have external weak linkage.
    1502             :       // We don't try to evaluate aliases here.
    1503             :       // NOTE: We should not be doing this constant folding if null pointer
    1504             :       // is considered valid for the function. But currently there is no way to
    1505             :       // query it from the Constant type.
    1506         551 :       if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV) &&
    1507          66 :           !NullPointerIsDefined(nullptr /* F */,
    1508             :                                 GV->getType()->getAddressSpace()))
    1509             :         return ICmpInst::ICMP_NE;
    1510             :     }
    1511             :   } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) {
    1512           1 :     if (isa<ConstantExpr>(V2)) {  // Swap as necessary.
    1513             :       ICmpInst::Predicate SwappedRelation =
    1514           0 :         evaluateICmpRelation(V2, V1, isSigned);
    1515           0 :       if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
    1516           0 :         return ICmpInst::getSwappedPredicate(SwappedRelation);
    1517             :       return ICmpInst::BAD_ICMP_PREDICATE;
    1518             :     }
    1519             : 
    1520             :     // Now we know that the RHS is a GlobalValue, BlockAddress or simple
    1521             :     // constant (which, since the types must match, means that it is a
    1522             :     // ConstantPointerNull).
    1523             :     if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) {
    1524             :       // Block address in another function can't equal this one, but block
    1525             :       // addresses in the current function might be the same if blocks are
    1526             :       // empty.
    1527           0 :       if (BA2->getFunction() != BA->getFunction())
    1528             :         return ICmpInst::ICMP_NE;
    1529             :     } else {
    1530             :       // Block addresses aren't null, don't equal the address of globals.
    1531             :       assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) &&
    1532             :              "Canonicalization guarantee!");
    1533             :       return ICmpInst::ICMP_NE;
    1534             :     }
    1535             :   } else {
    1536             :     // Ok, the LHS is known to be a constantexpr.  The RHS can be any of a
    1537             :     // constantexpr, a global, block address, or a simple constant.
    1538             :     ConstantExpr *CE1 = cast<ConstantExpr>(V1);
    1539             :     Constant *CE1Op0 = CE1->getOperand(0);
    1540             : 
    1541             :     switch (CE1->getOpcode()) {
    1542             :     case Instruction::Trunc:
    1543             :     case Instruction::FPTrunc:
    1544             :     case Instruction::FPExt:
    1545             :     case Instruction::FPToUI:
    1546             :     case Instruction::FPToSI:
    1547             :       break; // We can't evaluate floating point casts or truncations.
    1548             : 
    1549        1320 :     case Instruction::UIToFP:
    1550             :     case Instruction::SIToFP:
    1551             :     case Instruction::BitCast:
    1552             :     case Instruction::ZExt:
    1553             :     case Instruction::SExt:
    1554             :       // We can't evaluate floating point casts or truncations.
    1555        1320 :       if (CE1Op0->getType()->isFloatingPointTy())
    1556             :         break;
    1557             : 
    1558             :       // If the cast is not actually changing bits, and the second operand is a
    1559             :       // null pointer, do the comparison with the pre-casted value.
    1560        1320 :       if (V2->isNullValue() && CE1->getType()->isIntOrPtrTy()) {
    1561        1277 :         if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
    1562        1277 :         if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
    1563        1277 :         return evaluateICmpRelation(CE1Op0,
    1564             :                                     Constant::getNullValue(CE1Op0->getType()),
    1565        1277 :                                     isSigned);
    1566             :       }
    1567             :       break;
    1568             : 
    1569             :     case Instruction::GetElementPtr: {
    1570             :       GEPOperator *CE1GEP = cast<GEPOperator>(CE1);
    1571             :       // Ok, since this is a getelementptr, we know that the constant has a
    1572             :       // pointer type.  Check the various cases.
    1573        3142 :       if (isa<ConstantPointerNull>(V2)) {
    1574             :         // If we are comparing a GEP to a null pointer, check to see if the base
    1575             :         // of the GEP equals the null pointer.
    1576             :         if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
    1577        2790 :           if (GV->hasExternalWeakLinkage())
    1578             :             // Weak linkage GVals could be zero or not. We're comparing that
    1579             :             // to null pointer so its greater-or-equal
    1580           0 :             return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
    1581             :           else
    1582             :             // If its not weak linkage, the GVal must have a non-zero address
    1583             :             // so the result is greater-than
    1584        2790 :             return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
    1585         172 :         } else if (isa<ConstantPointerNull>(CE1Op0)) {
    1586             :           // If we are indexing from a null pointer, check to see if we have any
    1587             :           // non-zero indices.
    1588           3 :           for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
    1589           2 :             if (!CE1->getOperand(i)->isNullValue())
    1590             :               // Offsetting from null, must not be equal.
    1591           1 :               return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
    1592             :           // Only zero indexes from null, must still be zero.
    1593             :           return ICmpInst::ICMP_EQ;
    1594             :         }
    1595             :         // Otherwise, we can't really say if the first operand is null or not.
    1596             :       } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) {
    1597         132 :         if (isa<ConstantPointerNull>(CE1Op0)) {
    1598           0 :           if (GV2->hasExternalWeakLinkage())
    1599             :             // Weak linkage GVals could be zero or not. We're comparing it to
    1600             :             // a null pointer, so its less-or-equal
    1601           0 :             return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
    1602             :           else
    1603             :             // If its not weak linkage, the GVal must have a non-zero address
    1604             :             // so the result is less-than
    1605           0 :             return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
    1606             :         } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
    1607         132 :           if (GV == GV2) {
    1608             :             // If this is a getelementptr of the same global, then it must be
    1609             :             // different.  Because the types must match, the getelementptr could
    1610             :             // only have at most one index, and because we fold getelementptr's
    1611             :             // with a single zero index, it must be nonzero.
    1612             :             assert(CE1->getNumOperands() == 2 &&
    1613             :                    !CE1->getOperand(1)->isNullValue() &&
    1614             :                    "Surprising getelementptr!");
    1615           5 :             return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
    1616             :           } else {
    1617         127 :             if (CE1GEP->hasAllZeroIndices())
    1618           9 :               return areGlobalsPotentiallyEqual(GV, GV2);
    1619             :             return ICmpInst::BAD_ICMP_PREDICATE;
    1620             :           }
    1621             :         }
    1622             :       } else {
    1623             :         ConstantExpr *CE2 = cast<ConstantExpr>(V2);
    1624             :         Constant *CE2Op0 = CE2->getOperand(0);
    1625             : 
    1626             :         // There are MANY other foldings that we could perform here.  They will
    1627             :         // probably be added on demand, as they seem needed.
    1628          48 :         switch (CE2->getOpcode()) {
    1629             :         default: break;
    1630          45 :         case Instruction::GetElementPtr:
    1631             :           // By far the most common case to handle is when the base pointers are
    1632             :           // obviously to the same global.
    1633             :           if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
    1634             :             // Don't know relative ordering, but check for inequality.
    1635          36 :             if (CE1Op0 != CE2Op0) {
    1636             :               GEPOperator *CE2GEP = cast<GEPOperator>(CE2);
    1637          28 :               if (CE1GEP->hasAllZeroIndices() && CE2GEP->hasAllZeroIndices())
    1638             :                 return areGlobalsPotentiallyEqual(cast<GlobalValue>(CE1Op0),
    1639           4 :                                                   cast<GlobalValue>(CE2Op0));
    1640             :               return ICmpInst::BAD_ICMP_PREDICATE;
    1641             :             }
    1642             :             // Ok, we know that both getelementptr instructions are based on the
    1643             :             // same global.  From this, we can precisely determine the relative
    1644             :             // ordering of the resultant pointers.
    1645             :             unsigned i = 1;
    1646             : 
    1647             :             // The logic below assumes that the result of the comparison
    1648             :             // can be determined by finding the first index that differs.
    1649             :             // This doesn't work if there is over-indexing in any
    1650             :             // subsequent indices, so check for that case first.
    1651          16 :             if (!CE1->isGEPWithNoNotionalOverIndexing() ||
    1652           8 :                 !CE2->isGEPWithNoNotionalOverIndexing())
    1653             :                return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
    1654             : 
    1655             :             // Compare all of the operands the GEP's have in common.
    1656           8 :             gep_type_iterator GTI = gep_type_begin(CE1);
    1657          46 :             for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
    1658             :                  ++i, ++GTI)
    1659          36 :               switch (IdxCompare(CE1->getOperand(i),
    1660             :                                  CE2->getOperand(i), GTI.getIndexedType())) {
    1661           7 :               case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
    1662           0 :               case 1:  return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
    1663             :               case -2: return ICmpInst::BAD_ICMP_PREDICATE;
    1664             :               }
    1665             : 
    1666             :             // Ok, we ran out of things they have in common.  If any leftovers
    1667             :             // are non-zero then we have a difference, otherwise we are equal.
    1668           0 :             for (; i < CE1->getNumOperands(); ++i)
    1669           0 :               if (!CE1->getOperand(i)->isNullValue()) {
    1670           0 :                 if (isa<ConstantInt>(CE1->getOperand(i)))
    1671           0 :                   return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
    1672             :                 else
    1673             :                   return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
    1674             :               }
    1675             : 
    1676           0 :             for (; i < CE2->getNumOperands(); ++i)
    1677           0 :               if (!CE2->getOperand(i)->isNullValue()) {
    1678           0 :                 if (isa<ConstantInt>(CE2->getOperand(i)))
    1679           0 :                   return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
    1680             :                 else
    1681             :                   return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
    1682             :               }
    1683             :             return ICmpInst::ICMP_EQ;
    1684             :           }
    1685             :         }
    1686             :       }
    1687             :       break;
    1688             :     }
    1689             :     default:
    1690             :       break;
    1691             :     }
    1692             :   }
    1693             : 
    1694             :   return ICmpInst::BAD_ICMP_PREDICATE;
    1695             : }
    1696             : 
    1697       89725 : Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
    1698             :                                                Constant *C1, Constant *C2) {
    1699             :   Type *ResultTy;
    1700       89725 :   if (VectorType *VT = dyn_cast<VectorType>(C1->getType()))
    1701          84 :     ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()),
    1702          84 :                                VT->getNumElements());
    1703             :   else
    1704       89641 :     ResultTy = Type::getInt1Ty(C1->getContext());
    1705             : 
    1706             :   // Fold FCMP_FALSE/FCMP_TRUE unconditionally.
    1707       89725 :   if (pred == FCmpInst::FCMP_FALSE)
    1708           0 :     return Constant::getNullValue(ResultTy);
    1709             : 
    1710       89725 :   if (pred == FCmpInst::FCMP_TRUE)
    1711           0 :     return Constant::getAllOnesValue(ResultTy);
    1712             : 
    1713             :   // Handle some degenerate cases first
    1714      179254 :   if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
    1715         226 :     CmpInst::Predicate Predicate = CmpInst::Predicate(pred);
    1716             :     bool isIntegerPredicate = ICmpInst::isIntPredicate(Predicate);
    1717             :     // For EQ and NE, we can always pick a value for the undef to make the
    1718             :     // predicate pass or fail, so we can return undef.
    1719             :     // Also, if both operands are undef, we can return undef for int comparison.
    1720         226 :     if (ICmpInst::isEquality(Predicate) || (isIntegerPredicate && C1 == C2))
    1721         121 :       return UndefValue::get(ResultTy);
    1722             : 
    1723             :     // Otherwise, for integer compare, pick the same value as the non-undef
    1724             :     // operand, and fold it to true or false.
    1725         105 :     if (isIntegerPredicate)
    1726          67 :       return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(Predicate));
    1727             : 
    1728             :     // Choosing NaN for the undef will always make unordered comparison succeed
    1729             :     // and ordered comparison fails.
    1730          38 :     return ConstantInt::get(ResultTy, CmpInst::isUnordered(Predicate));
    1731             :   }
    1732             : 
    1733             :   // icmp eq/ne(null,GV) -> false/true
    1734       89499 :   if (C1->isNullValue()) {
    1735             :     if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
    1736             :       // Don't try to evaluate aliases.  External weak GV can be null.
    1737          12 :       if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage() &&
    1738           4 :           !NullPointerIsDefined(nullptr /* F */,
    1739             :                                 GV->getType()->getAddressSpace())) {
    1740           0 :         if (pred == ICmpInst::ICMP_EQ)
    1741           0 :           return ConstantInt::getFalse(C1->getContext());
    1742           0 :         else if (pred == ICmpInst::ICMP_NE)
    1743           0 :           return ConstantInt::getTrue(C1->getContext());
    1744             :       }
    1745             :   // icmp eq/ne(GV,null) -> false/true
    1746       56509 :   } else if (C2->isNullValue()) {
    1747             :     if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
    1748             :       // Don't try to evaluate aliases.  External weak GV can be null.
    1749         350 :       if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage() &&
    1750          75 :           !NullPointerIsDefined(nullptr /* F */,
    1751             :                                 GV->getType()->getAddressSpace())) {
    1752          31 :         if (pred == ICmpInst::ICMP_EQ)
    1753          10 :           return ConstantInt::getFalse(C1->getContext());
    1754          21 :         else if (pred == ICmpInst::ICMP_NE)
    1755          17 :           return ConstantInt::getTrue(C1->getContext());
    1756             :       }
    1757             :   }
    1758             : 
    1759             :   // If the comparison is a comparison between two i1's, simplify it.
    1760       89472 :   if (C1->getType()->isIntegerTy(1)) {
    1761         145 :     switch(pred) {
    1762          85 :     case ICmpInst::ICMP_EQ:
    1763          85 :       if (isa<ConstantInt>(C2))
    1764          85 :         return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2));
    1765           0 :       return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2);
    1766          16 :     case ICmpInst::ICMP_NE:
    1767          16 :       return ConstantExpr::getXor(C1, C2);
    1768             :     default:
    1769             :       break;
    1770             :     }
    1771             :   }
    1772             : 
    1773      160818 :   if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
    1774             :     const APInt &V1 = cast<ConstantInt>(C1)->getValue();
    1775             :     const APInt &V2 = cast<ConstantInt>(C2)->getValue();
    1776       71438 :     switch (pred) {
    1777           0 :     default: llvm_unreachable("Invalid ICmp Predicate");
    1778       23944 :     case ICmpInst::ICMP_EQ:  return ConstantInt::get(ResultTy, V1 == V2);
    1779        5278 :     case ICmpInst::ICMP_NE:  return ConstantInt::get(ResultTy, V1 != V2);
    1780        1593 :     case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2));
    1781       10217 :     case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2));
    1782         950 :     case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2));
    1783         649 :     case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2));
    1784       21742 :     case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2));
    1785        5197 :     case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2));
    1786        1117 :     case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2));
    1787         751 :     case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2));
    1788             :     }
    1789       18232 :   } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
    1790             :     const APFloat &C1V = cast<ConstantFP>(C1)->getValueAPF();
    1791             :     const APFloat &C2V = cast<ConstantFP>(C2)->getValueAPF();
    1792         299 :     APFloat::cmpResult R = C1V.compare(C2V);
    1793         299 :     switch (pred) {
    1794           0 :     default: llvm_unreachable("Invalid FCmp Predicate");
    1795           0 :     case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy);
    1796           0 :     case FCmpInst::FCMP_TRUE:  return Constant::getAllOnesValue(ResultTy);
    1797           9 :     case FCmpInst::FCMP_UNO:
    1798           9 :       return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered);
    1799           1 :     case FCmpInst::FCMP_ORD:
    1800           1 :       return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered);
    1801           7 :     case FCmpInst::FCMP_UEQ:
    1802          14 :       return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
    1803          14 :                                         R==APFloat::cmpEqual);
    1804          42 :     case FCmpInst::FCMP_OEQ:
    1805          42 :       return ConstantInt::get(ResultTy, R==APFloat::cmpEqual);
    1806          88 :     case FCmpInst::FCMP_UNE:
    1807          88 :       return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual);
    1808           3 :     case FCmpInst::FCMP_ONE:
    1809           6 :       return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan ||
    1810           6 :                                         R==APFloat::cmpGreaterThan);
    1811          10 :     case FCmpInst::FCMP_ULT:
    1812          20 :       return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
    1813          20 :                                         R==APFloat::cmpLessThan);
    1814          26 :     case FCmpInst::FCMP_OLT:
    1815          26 :       return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan);
    1816           4 :     case FCmpInst::FCMP_UGT:
    1817           4 :       return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
    1818           4 :                                         R==APFloat::cmpGreaterThan);
    1819          20 :     case FCmpInst::FCMP_OGT:
    1820          20 :       return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan);
    1821           0 :     case FCmpInst::FCMP_ULE:
    1822           0 :       return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan);
    1823          15 :     case FCmpInst::FCMP_OLE:
    1824          15 :       return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan ||
    1825          15 :                                         R==APFloat::cmpEqual);
    1826          39 :     case FCmpInst::FCMP_UGE:
    1827          39 :       return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan);
    1828          35 :     case FCmpInst::FCMP_OGE:
    1829          35 :       return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan ||
    1830          35 :                                         R==APFloat::cmpEqual);
    1831             :     }
    1832       35268 :   } else if (C1->getType()->isVectorTy()) {
    1833             :     // If we can constant fold the comparison of each element, constant fold
    1834             :     // the whole vector comparison.
    1835             :     SmallVector<Constant*, 4> ResElts;
    1836          71 :     Type *Ty = IntegerType::get(C1->getContext(), 32);
    1837             :     // Compare the elements, producing an i1 result or constant expr.
    1838         850 :     for (unsigned i = 0, e = C1->getType()->getVectorNumElements(); i != e;++i){
    1839             :       Constant *C1E =
    1840         354 :         ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i));
    1841             :       Constant *C2E =
    1842         354 :         ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i));
    1843             : 
    1844         354 :       ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E));
    1845             :     }
    1846             : 
    1847          71 :     return ConstantVector::get(ResElts);
    1848             :   }
    1849             : 
    1850           4 :   if (C1->getType()->isFloatingPointTy() &&
    1851             :       // Only call evaluateFCmpRelation if we have a constant expr to avoid
    1852             :       // infinite recursive loop
    1853           0 :       (isa<ConstantExpr>(C1) || isa<ConstantExpr>(C2))) {
    1854             :     int Result = -1;  // -1 = unknown, 0 = known false, 1 = known true.
    1855           4 :     switch (evaluateFCmpRelation(C1, C2)) {
    1856           0 :     default: llvm_unreachable("Unknown relation!");
    1857             :     case FCmpInst::FCMP_UNO:
    1858             :     case FCmpInst::FCMP_ORD:
    1859             :     case FCmpInst::FCMP_UEQ:
    1860             :     case FCmpInst::FCMP_UNE:
    1861             :     case FCmpInst::FCMP_ULT:
    1862             :     case FCmpInst::FCMP_UGT:
    1863             :     case FCmpInst::FCMP_ULE:
    1864             :     case FCmpInst::FCMP_UGE:
    1865             :     case FCmpInst::FCMP_TRUE:
    1866             :     case FCmpInst::FCMP_FALSE:
    1867             :     case FCmpInst::BAD_FCMP_PREDICATE:
    1868             :       break; // Couldn't determine anything about these constants.
    1869           0 :     case FCmpInst::FCMP_OEQ: // We know that C1 == C2
    1870           0 :       Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
    1871           0 :                 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
    1872           0 :                 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
    1873           0 :       break;
    1874           0 :     case FCmpInst::FCMP_OLT: // We know that C1 < C2
    1875           0 :       Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
    1876           0 :                 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
    1877           0 :                 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
    1878           0 :       break;
    1879           0 :     case FCmpInst::FCMP_OGT: // We know that C1 > C2
    1880           0 :       Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
    1881           0 :                 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
    1882           0 :                 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
    1883           0 :       break;
    1884           0 :     case FCmpInst::FCMP_OLE: // We know that C1 <= C2
    1885             :       // We can only partially decide this relation.
    1886           0 :       if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
    1887             :         Result = 0;
    1888           0 :       else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
    1889             :         Result = 1;
    1890             :       break;
    1891           0 :     case FCmpInst::FCMP_OGE: // We known that C1 >= C2
    1892             :       // We can only partially decide this relation.
    1893           0 :       if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
    1894             :         Result = 0;
    1895           0 :       else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
    1896             :         Result = 1;
    1897             :       break;
    1898           0 :     case FCmpInst::FCMP_ONE: // We know that C1 != C2
    1899             :       // We can only partially decide this relation.
    1900           0 :       if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
    1901             :         Result = 0;
    1902           0 :       else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
    1903             :         Result = 1;
    1904             :       break;
    1905             :     }
    1906             : 
    1907             :     // If we evaluated the result, return it now.
    1908             :     if (Result != -1)
    1909           0 :       return ConstantInt::get(ResultTy, Result);
    1910             : 
    1911             :   } else {
    1912             :     // Evaluate the relation between the two constants, per the predicate.
    1913             :     int Result = -1;  // -1 = unknown, 0 = known false, 1 = known true.
    1914       17559 :     switch (evaluateICmpRelation(C1, C2,
    1915       17559 :                                  CmpInst::isSigned((CmpInst::Predicate)pred))) {
    1916           0 :     default: llvm_unreachable("Unknown relational!");
    1917             :     case ICmpInst::BAD_ICMP_PREDICATE:
    1918             :       break;  // Couldn't determine anything about these constants.
    1919       11789 :     case ICmpInst::ICMP_EQ:   // We know the constants are equal!
    1920             :       // If we know the constants are equal, we can decide the result of this
    1921             :       // computation precisely.
    1922       11789 :       Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred);
    1923       11789 :       break;
    1924           7 :     case ICmpInst::ICMP_ULT:
    1925             :       switch (pred) {
    1926             :       case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE:
    1927             :         Result = 1; break;
    1928             :       case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE:
    1929             :         Result = 0; break;
    1930             :       }
    1931             :       break;
    1932           4 :     case ICmpInst::ICMP_SLT:
    1933             :       switch (pred) {
    1934             :       case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE:
    1935             :         Result = 1; break;
    1936             :       case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE:
    1937             :         Result = 0; break;
    1938             :       }
    1939             :       break;
    1940        2792 :     case ICmpInst::ICMP_UGT:
    1941             :       switch (pred) {
    1942             :       case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE:
    1943             :         Result = 1; break;
    1944             :       case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE:
    1945             :         Result = 0; break;
    1946             :       }
    1947             :       break;
    1948           0 :     case ICmpInst::ICMP_SGT:
    1949             :       switch (pred) {
    1950             :       case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE:
    1951             :         Result = 1; break;
    1952             :       case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE:
    1953             :         Result = 0; break;
    1954             :       }
    1955             :       break;
    1956           0 :     case ICmpInst::ICMP_ULE:
    1957           0 :       if (pred == ICmpInst::ICMP_UGT) Result = 0;
    1958           0 :       if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1;
    1959             :       break;
    1960           0 :     case ICmpInst::ICMP_SLE:
    1961           0 :       if (pred == ICmpInst::ICMP_SGT) Result = 0;
    1962           0 :       if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1;
    1963             :       break;
    1964           0 :     case ICmpInst::ICMP_UGE:
    1965           0 :       if (pred == ICmpInst::ICMP_ULT) Result = 0;
    1966           0 :       if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1;
    1967             :       break;
    1968           0 :     case ICmpInst::ICMP_SGE:
    1969           0 :       if (pred == ICmpInst::ICMP_SLT) Result = 0;
    1970           0 :       if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1;
    1971             :       break;
    1972          70 :     case ICmpInst::ICMP_NE:
    1973          70 :       if (pred == ICmpInst::ICMP_EQ) Result = 0;
    1974          70 :       if (pred == ICmpInst::ICMP_NE) Result = 1;
    1975             :       break;
    1976             :     }
    1977             : 
    1978             :     // If we evaluated the result, return it now.
    1979       11856 :     if (Result != -1)
    1980       14625 :       return ConstantInt::get(ResultTy, Result);
    1981             : 
    1982             :     // If the right hand side is a bitcast, try using its inverse to simplify
    1983             :     // it by moving it to the left hand side.  We can't do this if it would turn
    1984             :     // a vector compare into a scalar compare or visa versa.
    1985             :     if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) {
    1986             :       Constant *CE2Op0 = CE2->getOperand(0);
    1987         404 :       if (CE2->getOpcode() == Instruction::BitCast &&
    1988          38 :           CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) {
    1989          19 :         Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType());
    1990          19 :         return ConstantExpr::getICmp(pred, Inverse, CE2Op0);
    1991             :       }
    1992             :     }
    1993             : 
    1994             :     // If the left hand side is an extension, try eliminating it.
    1995             :     if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
    1996           0 :       if ((CE1->getOpcode() == Instruction::SExt &&
    1997        5422 :            ICmpInst::isSigned((ICmpInst::Predicate)pred)) ||
    1998         732 :           (CE1->getOpcode() == Instruction::ZExt &&
    1999         732 :            !ICmpInst::isSigned((ICmpInst::Predicate)pred))){
    2000             :         Constant *CE1Op0 = CE1->getOperand(0);
    2001          35 :         Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType());
    2002          35 :         if (CE1Inverse == CE1Op0) {
    2003             :           // Check whether we can safely truncate the right hand side.
    2004          35 :           Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType());
    2005          70 :           if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse,
    2006             :                                     C2->getType()) == C2)
    2007          35 :             return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse);
    2008             :         }
    2009             :       }
    2010             :     }
    2011             : 
    2012        5953 :     if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) ||
    2013        2873 :         (C1->isNullValue() && !C2->isNullValue())) {
    2014             :       // If C2 is a constant expr and C1 isn't, flip them around and fold the
    2015             :       // other way if possible.
    2016             :       // Also, if C1 is null and C2 isn't, flip them around.
    2017          15 :       pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
    2018          15 :       return ConstantExpr::getICmp(pred, C2, C1);
    2019             :     }
    2020             :   }
    2021             :   return nullptr;
    2022             : }
    2023             : 
    2024             : /// Test whether the given sequence of *normalized* indices is "inbounds".
    2025             : template<typename IndexTy>
    2026      212108 : static bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) {
    2027             :   // No indices means nothing that could be out of bounds.
    2028      212108 :   if (Idxs.empty()) return true;
    2029             : 
    2030             :   // If the first index is zero, it's in bounds.
    2031      212108 :   if (cast<Constant>(Idxs[0])->isNullValue()) return true;
    2032             : 
    2033             :   // If the first index is one and all the rest are zero, it's in bounds,
    2034             :   // by the one-past-the-end rule.
    2035         216 :   if (auto *CI = dyn_cast<ConstantInt>(Idxs[0])) {
    2036         215 :     if (!CI->isOne())
    2037             :       return false;
    2038             :   } else {
    2039             :     auto *CV = cast<ConstantDataVector>(Idxs[0]);
    2040           1 :     CI = dyn_cast_or_null<ConstantInt>(CV->getSplatValue());
    2041           1 :     if (!CI || !CI->isOne())
    2042             :       return false;
    2043             :   }
    2044             : 
    2045         113 :   for (unsigned i = 1, e = Idxs.size(); i != e; ++i)
    2046         104 :     if (!cast<Constant>(Idxs[i])->isNullValue())
    2047             :       return false;
    2048             :   return true;
    2049             : }
    2050             : 
    2051             : /// Test whether a given ConstantInt is in-range for a SequentialType.
    2052    10964286 : static bool isIndexInRangeOfArrayType(uint64_t NumElements,
    2053             :                                       const ConstantInt *CI) {
    2054             :   // We cannot bounds check the index if it doesn't fit in an int64_t.
    2055    10964286 :   if (CI->getValue().getActiveBits() > 64)
    2056             :     return false;
    2057             : 
    2058             :   // A negative index or an index past the end of our sequential type is
    2059             :   // considered out-of-range.
    2060             :   int64_t IndexVal = CI->getSExtValue();
    2061    10964286 :   if (IndexVal < 0 || (NumElements > 0 && (uint64_t)IndexVal >= NumElements))
    2062             :     return false;
    2063             : 
    2064             :   // Otherwise, it is in-range.
    2065    10963702 :   return true;
    2066             : }
    2067             : 
    2068    11029975 : Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C,
    2069             :                                           bool InBounds,
    2070             :                                           Optional<unsigned> InRangeIndex,
    2071             :                                           ArrayRef<Value *> Idxs) {
    2072    11029975 :   if (Idxs.empty()) return C;
    2073             : 
    2074             :   Type *GEPTy = GetElementPtrInst::getGEPReturnType(
    2075    11029973 :       C, makeArrayRef((Value *const *)Idxs.data(), Idxs.size()));
    2076             : 
    2077    11029973 :   if (isa<UndefValue>(C))
    2078          54 :     return UndefValue::get(GEPTy);
    2079             : 
    2080    11029919 :   Constant *Idx0 = cast<Constant>(Idxs[0]);
    2081    11037603 :   if (Idxs.size() == 1 && (Idx0->isNullValue() || isa<UndefValue>(Idx0)))
    2082          10 :     return GEPTy->isVectorTy() && !C->getType()->isVectorTy()
    2083         698 :                ? ConstantVector::getSplat(
    2084           2 :                      cast<VectorType>(GEPTy)->getNumElements(), C)
    2085             :                : C;
    2086             : 
    2087    11029223 :   if (C->isNullValue()) {
    2088             :     bool isNull = true;
    2089        3833 :     for (unsigned i = 0, e = Idxs.size(); i != e; ++i)
    2090       15184 :       if (!isa<UndefValue>(Idxs[i]) &&
    2091        3796 :           !cast<Constant>(Idxs[i])->isNullValue()) {
    2092             :         isNull = false;
    2093             :         break;
    2094             :       }
    2095        2282 :     if (isNull) {
    2096          37 :       PointerType *PtrTy = cast<PointerType>(C->getType()->getScalarType());
    2097          37 :       Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs);
    2098             : 
    2099             :       assert(Ty && "Invalid indices for GEP!");
    2100          37 :       Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
    2101          37 :       Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
    2102          37 :       if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
    2103           2 :         GEPTy = VectorType::get(OrigGEPTy, VT->getNumElements());
    2104             : 
    2105             :       // The GEP returns a vector of pointers when one of more of
    2106             :       // its arguments is a vector.
    2107         179 :       for (unsigned i = 0, e = Idxs.size(); i != e; ++i) {
    2108         148 :         if (auto *VT = dyn_cast<VectorType>(Idxs[i]->getType())) {
    2109           3 :           GEPTy = VectorType::get(OrigGEPTy, VT->getNumElements());
    2110           3 :           break;
    2111             :         }
    2112             :       }
    2113             : 
    2114          37 :       return Constant::getNullValue(GEPTy);
    2115             :     }
    2116             :   }
    2117             : 
    2118             :   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
    2119             :     // Combine Indices - If the source pointer to this getelementptr instruction
    2120             :     // is a getelementptr instruction, combine the indices of the two
    2121             :     // getelementptr instructions into a single instruction.
    2122             :     //
    2123        7142 :     if (CE->getOpcode() == Instruction::GetElementPtr) {
    2124             :       gep_type_iterator LastI = gep_type_end(CE);
    2125       10571 :       for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
    2126       10571 :            I != E; ++I)
    2127        7274 :         LastI = I;
    2128             : 
    2129             :       // We cannot combine indices if doing so would take us outside of an
    2130             :       // array or vector.  Doing otherwise could trick us if we evaluated such a
    2131             :       // GEP as part of a load.
    2132             :       //
    2133             :       // e.g. Consider if the original GEP was:
    2134             :       // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
    2135             :       //                    i32 0, i32 0, i64 0)
    2136             :       //
    2137             :       // If we then tried to offset it by '8' to get to the third element,
    2138             :       // an i8, we should *not* get:
    2139             :       // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
    2140             :       //                    i32 0, i32 0, i64 8)
    2141             :       //
    2142             :       // This GEP tries to index array element '8  which runs out-of-bounds.
    2143             :       // Subsequent evaluation would get confused and produce erroneous results.
    2144             :       //
    2145             :       // The following prohibits such a GEP from being formed by checking to see
    2146             :       // if the index is in-range with respect to an array.
    2147             :       // TODO: This code may be extended to handle vectors as well.
    2148             :       bool PerformFold = false;
    2149        3297 :       if (Idx0->isNullValue())
    2150             :         PerformFold = true;
    2151        1591 :       else if (LastI.isSequential())
    2152             :         if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx0))
    2153        1509 :           PerformFold = (!LastI.isBoundedSequential() ||
    2154        1509 :                          isIndexInRangeOfArrayType(
    2155        1101 :                              LastI.getSequentialNumElements(), CI)) &&
    2156        1101 :                         !CE->getOperand(CE->getNumOperands() - 1)
    2157             :                              ->getType()
    2158        1101 :                              ->isVectorTy();
    2159             : 
    2160             :       if (PerformFold) {
    2161             :         SmallVector<Value*, 16> NewIndices;
    2162        2806 :         NewIndices.reserve(Idxs.size() + CE->getNumOperands());
    2163        5612 :         NewIndices.append(CE->op_begin() + 1, CE->op_end() - 1);
    2164             : 
    2165             :         // Add the last index of the source with the first index of the new GEP.
    2166             :         // Make sure to handle the case when they are actually different types.
    2167        2806 :         Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
    2168             :         // Otherwise it must be an array.
    2169        2806 :         if (!Idx0->isNullValue()) {
    2170        1100 :           Type *IdxTy = Combined->getType();
    2171        1100 :           if (IdxTy != Idx0->getType()) {
    2172             :             unsigned CommonExtendedWidth =
    2173         231 :                 std::max(IdxTy->getIntegerBitWidth(),
    2174         231 :                          Idx0->getType()->getIntegerBitWidth());
    2175         154 :             CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
    2176             : 
    2177             :             Type *CommonTy =
    2178          77 :                 Type::getIntNTy(IdxTy->getContext(), CommonExtendedWidth);
    2179          77 :             Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, CommonTy);
    2180          77 :             Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, CommonTy);
    2181          77 :             Combined = ConstantExpr::get(Instruction::Add, C1, C2);
    2182             :           } else {
    2183        1023 :             Combined =
    2184             :               ConstantExpr::get(Instruction::Add, Idx0, Combined);
    2185             :           }
    2186             :         }
    2187             : 
    2188        2806 :         NewIndices.push_back(Combined);
    2189        2806 :         NewIndices.append(Idxs.begin() + 1, Idxs.end());
    2190             : 
    2191             :         // The combined GEP normally inherits its index inrange attribute from
    2192             :         // the inner GEP, but if the inner GEP's last index was adjusted by the
    2193             :         // outer GEP, any inbounds attribute on that index is invalidated.
    2194             :         Optional<unsigned> IRIndex = cast<GEPOperator>(CE)->getInRangeIndex();
    2195        2812 :         if (IRIndex && *IRIndex == CE->getNumOperands() - 2 && !Idx0->isNullValue())
    2196             :           IRIndex = None;
    2197             : 
    2198        8418 :         return ConstantExpr::getGetElementPtr(
    2199             :             cast<GEPOperator>(CE)->getSourceElementType(), CE->getOperand(0),
    2200        3793 :             NewIndices, InBounds && cast<GEPOperator>(CE)->isInBounds(),
    2201        2806 :             IRIndex);
    2202             :       }
    2203             :     }
    2204             : 
    2205             :     // Attempt to fold casts to the same type away.  For example, folding:
    2206             :     //
    2207             :     //   i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*),
    2208             :     //                       i64 0, i64 0)
    2209             :     // into:
    2210             :     //
    2211             :     //   i32* getelementptr ([3 x i32]* %X, i64 0, i64 0)
    2212             :     //
    2213             :     // Don't fold if the cast is changing address spaces.
    2214        4336 :     if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) {
    2215             :       PointerType *SrcPtrTy =
    2216         603 :         dyn_cast<PointerType>(CE->getOperand(0)->getType());
    2217         603 :       PointerType *DstPtrTy = dyn_cast<PointerType>(CE->getType());
    2218         603 :       if (SrcPtrTy && DstPtrTy) {
    2219             :         ArrayType *SrcArrayTy =
    2220         434 :           dyn_cast<ArrayType>(SrcPtrTy->getElementType());
    2221             :         ArrayType *DstArrayTy =
    2222         434 :           dyn_cast<ArrayType>(DstPtrTy->getElementType());
    2223         434 :         if (SrcArrayTy && DstArrayTy
    2224         111 :             && SrcArrayTy->getElementType() == DstArrayTy->getElementType()
    2225         537 :             && SrcPtrTy->getAddressSpace() == DstPtrTy->getAddressSpace())
    2226          50 :           return ConstantExpr::getGetElementPtr(SrcArrayTy,
    2227             :                                                 (Constant *)CE->getOperand(0),
    2228          25 :                                                 Idxs, InBounds, InRangeIndex);
    2229             :       }
    2230             :     }
    2231             :   }
    2232             : 
    2233             :   // Check to see if any array indices are not within the corresponding
    2234             :   // notional array or vector bounds. If so, try to determine if they can be
    2235             :   // factored out into preceding dimensions.
    2236             :   SmallVector<Constant *, 8> NewIdxs;
    2237             :   Type *Ty = PointeeTy;
    2238    11026355 :   Type *Prev = C->getType();
    2239             :   bool Unknown =
    2240    22052710 :       !isa<ConstantInt>(Idxs[0]) && !isa<ConstantDataVector>(Idxs[0]);
    2241    22088847 :   for (unsigned i = 1, e = Idxs.size(); i != e;
    2242    11062492 :        Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) {
    2243    33187522 :     if (!isa<ConstantInt>(Idxs[i]) && !isa<ConstantDataVector>(Idxs[i])) {
    2244             :       // We don't know if it's in range or not.
    2245             :       Unknown = true;
    2246    11062477 :       continue;
    2247             :     }
    2248    33187400 :     if (!isa<ConstantInt>(Idxs[i - 1]) && !isa<ConstantDataVector>(Idxs[i - 1]))
    2249             :       // Skip if the type of the previous index is not supported.
    2250          12 :       continue;
    2251    11146089 :     if (InRangeIndex && i == *InRangeIndex + 1) {
    2252             :       // If an index is marked inrange, we cannot apply this canonicalization to
    2253             :       // the following index, as that will cause the inrange index to point to
    2254             :       // the wrong element.
    2255       27885 :       continue;
    2256             :     }
    2257    11106368 :     if (isa<StructType>(Ty)) {
    2258             :       // The verify makes sure that GEPs into a struct are in range.
    2259       71819 :       continue;
    2260             :     }
    2261             :     auto *STy = cast<SequentialType>(Ty);
    2262    10962730 :     if (isa<VectorType>(STy)) {
    2263             :       // There can be awkward padding in after a non-power of two vector.
    2264             :       Unknown = true;
    2265          16 :       continue;
    2266             :     }
    2267             :     if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) {
    2268    10962683 :       if (isIndexInRangeOfArrayType(STy->getNumElements(), CI))
    2269             :         // It's in range, skip to the next index.
    2270    10962517 :         continue;
    2271         166 :       if (CI->getSExtValue() < 0) {
    2272             :         // It's out of range and negative, don't try to factor it.
    2273             :         Unknown = true;
    2274          77 :         continue;
    2275             :       }
    2276             :     } else {
    2277             :       auto *CV = cast<ConstantDataVector>(Idxs[i]);
    2278             :       bool InRange = true;
    2279         125 :       for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) {
    2280          94 :         auto *CI = cast<ConstantInt>(CV->getElementAsConstant(I));
    2281          94 :         InRange &= isIndexInRangeOfArrayType(STy->getNumElements(), CI);
    2282          94 :         if (CI->getSExtValue() < 0) {
    2283             :           Unknown = true;
    2284             :           break;
    2285             :         }
    2286             :       }
    2287          31 :       if (InRange || Unknown)
    2288             :         // It's in range, skip to the next index.
    2289             :         // It's out of range and negative, don't try to factor it.
    2290          27 :         continue;
    2291             :     }
    2292          93 :     if (isa<StructType>(Prev)) {
    2293             :       // It's out of range, but the prior dimension is a struct
    2294             :       // so we can't do anything about it.
    2295             :       Unknown = true;
    2296          32 :       continue;
    2297             :     }
    2298             :     // It's out of range, but we can factor it into the prior
    2299             :     // dimension.
    2300          61 :     NewIdxs.resize(Idxs.size());
    2301             :     // Determine the number of elements in our sequential type.
    2302             :     uint64_t NumElements = STy->getArrayNumElements();
    2303             : 
    2304             :     // Expand the current index or the previous index to a vector from a scalar
    2305             :     // if necessary.
    2306          61 :     Constant *CurrIdx = cast<Constant>(Idxs[i]);
    2307             :     auto *PrevIdx =
    2308          61 :         NewIdxs[i - 1] ? NewIdxs[i - 1] : cast<Constant>(Idxs[i - 1]);
    2309          61 :     bool IsCurrIdxVector = CurrIdx->getType()->isVectorTy();
    2310          61 :     bool IsPrevIdxVector = PrevIdx->getType()->isVectorTy();
    2311          61 :     bool UseVector = IsCurrIdxVector || IsPrevIdxVector;
    2312             : 
    2313          61 :     if (!IsCurrIdxVector && IsPrevIdxVector)
    2314           1 :       CurrIdx = ConstantDataVector::getSplat(
    2315             :           PrevIdx->getType()->getVectorNumElements(), CurrIdx);
    2316             : 
    2317          61 :     if (!IsPrevIdxVector && IsCurrIdxVector)
    2318           2 :       PrevIdx = ConstantDataVector::getSplat(
    2319             :           CurrIdx->getType()->getVectorNumElements(), PrevIdx);
    2320             : 
    2321             :     Constant *Factor =
    2322         122 :         ConstantInt::get(CurrIdx->getType()->getScalarType(), NumElements);
    2323          61 :     if (UseVector)
    2324          10 :       Factor = ConstantDataVector::getSplat(
    2325           4 :           IsPrevIdxVector ? PrevIdx->getType()->getVectorNumElements()
    2326           1 :                           : CurrIdx->getType()->getVectorNumElements(),
    2327             :           Factor);
    2328             : 
    2329          61 :     NewIdxs[i] = ConstantExpr::getSRem(CurrIdx, Factor);
    2330             : 
    2331          61 :     Constant *Div = ConstantExpr::getSDiv(CurrIdx, Factor);
    2332             : 
    2333             :     unsigned CommonExtendedWidth =
    2334         183 :         std::max(PrevIdx->getType()->getScalarSizeInBits(),
    2335         183 :                  Div->getType()->getScalarSizeInBits());
    2336         122 :     CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
    2337             : 
    2338             :     // Before adding, extend both operands to i64 to avoid
    2339             :     // overflow trouble.
    2340          61 :     Type *ExtendedTy = Type::getIntNTy(Div->getContext(), CommonExtendedWidth);
    2341          61 :     if (UseVector)
    2342          10 :       ExtendedTy = VectorType::get(
    2343             :           ExtendedTy, IsPrevIdxVector
    2344           4 :                           ? PrevIdx->getType()->getVectorNumElements()
    2345           1 :                           : CurrIdx->getType()->getVectorNumElements());
    2346             : 
    2347         122 :     if (!PrevIdx->getType()->isIntOrIntVectorTy(CommonExtendedWidth))
    2348          22 :       PrevIdx = ConstantExpr::getSExt(PrevIdx, ExtendedTy);
    2349             : 
    2350         122 :     if (!Div->getType()->isIntOrIntVectorTy(CommonExtendedWidth))
    2351          14 :       Div = ConstantExpr::getSExt(Div, ExtendedTy);
    2352             : 
    2353          61 :     NewIdxs[i - 1] = ConstantExpr::getAdd(PrevIdx, Div);
    2354             :   }
    2355             : 
    2356             :   // If we did any factoring, start over with the adjusted indices.
    2357    11026355 :   if (!NewIdxs.empty()) {
    2358         403 :     for (unsigned i = 0, e = Idxs.size(); i != e; ++i)
    2359         399 :       if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]);
    2360          57 :     return ConstantExpr::getGetElementPtr(PointeeTy, C, NewIdxs, InBounds,
    2361             :                                           InRangeIndex);
    2362             :   }
    2363             : 
    2364             :   // If all indices are known integers and normalized, we can do a simple
    2365             :   // check for the "inbounds" property.
    2366    11026298 :   if (!Unknown && !InBounds)
    2367             :     if (auto *GV = dyn_cast<GlobalVariable>(C))
    2368      212168 :       if (!GV->hasExternalWeakLinkage() && isInBoundsIndices(Idxs))
    2369      211953 :         return ConstantExpr::getGetElementPtr(PointeeTy, C, Idxs,
    2370      211953 :                                               /*InBounds=*/true, InRangeIndex);
    2371             : 
    2372             :   return nullptr;
    2373             : }

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