lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

   1 //===- InstCombineAndOrXor.cpp --------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the visitAnd, visitOr, and visitXor functions.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "InstCombine.h"
  15 #include "llvm/Intrinsics.h"
  16 #include "llvm/Analysis/InstructionSimplify.h"
  17 #include "llvm/Support/ConstantRange.h"
  18 #include "llvm/Support/PatternMatch.h"
  19 using namespace llvm;
  20 using namespace PatternMatch;
  21
  22
  23 /// AddOne - Add one to a ConstantInt.
  24 static Constant *AddOne(Constant *C) {
  25   return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
  26 }
  27 /// SubOne - Subtract one from a ConstantInt.
  28 static Constant *SubOne(ConstantInt *C) {
  29   return ConstantInt::get(C->getContext(), C->getValue()-1);
  30 }
  31
  32 /// isFreeToInvert - Return true if the specified value is free to invert (apply
  33 /// ~ to).  This happens in cases where the ~ can be eliminated.
  34 static inline bool isFreeToInvert(Value *V) {
  35   // ~(~(X)) -> X.
  36   if (BinaryOperator::isNot(V))
  37     return true;
  38
  39   // Constants can be considered to be not'ed values.
  40   if (isa<ConstantInt>(V))
  41     return true;
  42
  43   // Compares can be inverted if they have a single use.
  44   if (CmpInst *CI = dyn_cast<CmpInst>(V))
  45     return CI->hasOneUse();
  46
  47   return false;
  48 }
  49
  50 static inline Value *dyn_castNotVal(Value *V) {
  51   // If this is not(not(x)) don't return that this is a not: we want the two
  52   // not's to be folded first.
  53   if (BinaryOperator::isNot(V)) {
  54     Value *Operand = BinaryOperator::getNotArgument(V);
  55     if (!isFreeToInvert(Operand))
  56       return Operand;
  57   }
  58
  59   // Constants can be considered to be not'ed values...
  60   if (ConstantInt *C = dyn_cast<ConstantInt>(V))
  61     return ConstantInt::get(C->getType(), ~C->getValue());
  62   return 0;
  63 }
  64
  65
  66 /// getICmpCode - Encode a icmp predicate into a three bit mask.  These bits
  67 /// are carefully arranged to allow folding of expressions such as:
  68 ///
  69 ///      (A < B) | (A > B) --> (A != B)
  70 ///
  71 /// Note that this is only valid if the first and second predicates have the
  72 /// same sign. Is illegal to do: (A u< B) | (A s> B)
  73 ///
  74 /// Three bits are used to represent the condition, as follows:
  75 ///   0  A > B
  76 ///   1  A == B
  77 ///   2  A < B
  78 ///
  79 /// <=>  Value  Definition
  80 /// 000     0   Always false
  81 /// 001     1   A >  B
  82 /// 010     2   A == B
  83 /// 011     3   A >= B
  84 /// 100     4   A <  B
  85 /// 101     5   A != B
  86 /// 110     6   A <= B
  87 /// 111     7   Always true
  88 ///
  89 static unsigned getICmpCode(const ICmpInst *ICI) {
  90   switch (ICI->getPredicate()) {
  91     // False -> 0
  92   case ICmpInst::ICMP_UGT: return 1;  // 001
  93   case ICmpInst::ICMP_SGT: return 1;  // 001
  94   case ICmpInst::ICMP_EQ:  return 2;  // 010
  95   case ICmpInst::ICMP_UGE: return 3;  // 011
  96   case ICmpInst::ICMP_SGE: return 3;  // 011
  97   case ICmpInst::ICMP_ULT: return 4;  // 100
  98   case ICmpInst::ICMP_SLT: return 4;  // 100
  99   case ICmpInst::ICMP_NE:  return 5;  // 101
 100   case ICmpInst::ICMP_ULE: return 6;  // 110
 101   case ICmpInst::ICMP_SLE: return 6;  // 110
 102     // True -> 7
 103   default:
 104     llvm_unreachable("Invalid ICmp predicate!");
 105     return 0;
 106   }
 107 }
 108
 109 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
 110 /// predicate into a three bit mask. It also returns whether it is an ordered
 111 /// predicate by reference.
 112 static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
 113   isOrdered = false;
 114   switch (CC) {
 115   case FCmpInst::FCMP_ORD: isOrdered = true; return 0;  // 000
 116   case FCmpInst::FCMP_UNO:                   return 0;  // 000
 117   case FCmpInst::FCMP_OGT: isOrdered = true; return 1;  // 001
 118   case FCmpInst::FCMP_UGT:                   return 1;  // 001
 119   case FCmpInst::FCMP_OEQ: isOrdered = true; return 2;  // 010
 120   case FCmpInst::FCMP_UEQ:                   return 2;  // 010
 121   case FCmpInst::FCMP_OGE: isOrdered = true; return 3;  // 011
 122   case FCmpInst::FCMP_UGE:                   return 3;  // 011
 123   case FCmpInst::FCMP_OLT: isOrdered = true; return 4;  // 100
 124   case FCmpInst::FCMP_ULT:                   return 4;  // 100
 125   case FCmpInst::FCMP_ONE: isOrdered = true; return 5;  // 101
 126   case FCmpInst::FCMP_UNE:                   return 5;  // 101
 127   case FCmpInst::FCMP_OLE: isOrdered = true; return 6;  // 110
 128   case FCmpInst::FCMP_ULE:                   return 6;  // 110
 129     // True -> 7
 130   default:
 131     // Not expecting FCMP_FALSE and FCMP_TRUE;
 132     llvm_unreachable("Unexpected FCmp predicate!");
 133     return 0;
 134   }
 135 }
 136
 137 /// getICmpValue - This is the complement of getICmpCode, which turns an
 138 /// opcode and two operands into either a constant true or false, or a brand
 139 /// new ICmp instruction. The sign is passed in to determine which kind
 140 /// of predicate to use in the new icmp instruction.
 141 static Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
 142                            InstCombiner::BuilderTy *Builder) {
 143   CmpInst::Predicate Pred;
 144   switch (Code) {
 145   default: assert(0 && "Illegal ICmp code!");
 146   case 0: // False.
 147     return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
 148   case 1: Pred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
 149   case 2: Pred = ICmpInst::ICMP_EQ; break;
 150   case 3: Pred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
 151   case 4: Pred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
 152   case 5: Pred = ICmpInst::ICMP_NE; break;
 153   case 6: Pred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
 154   case 7: // True.
 155     return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
 156   }
 157   return Builder->CreateICmp(Pred, LHS, RHS);
 158 }
 159
 160 /// getFCmpValue - This is the complement of getFCmpCode, which turns an
 161 /// opcode and two operands into either a FCmp instruction. isordered is passed
 162 /// in to determine which kind of predicate to use in the new fcmp instruction.
 163 static Value *getFCmpValue(bool isordered, unsigned code,
 164                            Value *LHS, Value *RHS,
 165                            InstCombiner::BuilderTy *Builder) {
 166   CmpInst::Predicate Pred;
 167   switch (code) {
 168   default: assert(0 && "Illegal FCmp code!");
 169   case 0: Pred = isordered ? FCmpInst::FCMP_ORD : FCmpInst::FCMP_UNO; break;
 170   case 1: Pred = isordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; break;
 171   case 2: Pred = isordered ? FCmpInst::FCMP_OEQ : FCmpInst::FCMP_UEQ; break;
 172   case 3: Pred = isordered ? FCmpInst::FCMP_OGE : FCmpInst::FCMP_UGE; break;
 173   case 4: Pred = isordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; break;
 174   case 5: Pred = isordered ? FCmpInst::FCMP_ONE : FCmpInst::FCMP_UNE; break;
 175   case 6: Pred = isordered ? FCmpInst::FCMP_OLE : FCmpInst::FCMP_ULE; break;
 176   case 7:
 177     if (!isordered) return ConstantInt::getTrue(LHS->getContext());
 178     Pred = FCmpInst::FCMP_ORD; break;
 179   }
 180   return Builder->CreateFCmp(Pred, LHS, RHS);
 181 }
 182
 183 /// PredicatesFoldable - Return true if both predicates match sign or if at
 184 /// least one of them is an equality comparison (which is signless).
 185 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
 186   return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
 187          (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
 188          (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
 189 }
 190
 191 // OptAndOp - This handles expressions of the form ((val OP C1) & C2).  Where
 192 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'.  Op is
 193 // guaranteed to be a binary operator.
 194 Instruction *InstCombiner::OptAndOp(Instruction *Op,
 195                                     ConstantInt *OpRHS,
 196                                     ConstantInt *AndRHS,
 197                                     BinaryOperator &TheAnd) {
 198   Value *X = Op->getOperand(0);
 199   Constant *Together = 0;
 200   if (!Op->isShift())
 201     Together = ConstantExpr::getAnd(AndRHS, OpRHS);
 202
 203   switch (Op->getOpcode()) {
 204   case Instruction::Xor:
 205     if (Op->hasOneUse()) {
 206       // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
 207       Value *And = Builder->CreateAnd(X, AndRHS);
 208       And->takeName(Op);
 209       return BinaryOperator::CreateXor(And, Together);
 210     }
 211     break;
 212   case Instruction::Or:
 213     if (Op->hasOneUse()){
 214       if (Together != OpRHS) {
 215         // (X | C1) & C2 --> (X | (C1&C2)) & C2
 216         Value *Or = Builder->CreateOr(X, Together);
 217         Or->takeName(Op);
 218         return BinaryOperator::CreateAnd(Or, AndRHS);
 219       }
 220
 221       ConstantInt *TogetherCI = dyn_cast<ConstantInt>(Together);
 222       if (TogetherCI && !TogetherCI->isZero()){
 223         // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1
 224         // NOTE: This reduces the number of bits set in the & mask, which
 225         // can expose opportunities for store narrowing.
 226         Together = ConstantExpr::getXor(AndRHS, Together);
 227         Value *And = Builder->CreateAnd(X, Together);
 228         And->takeName(Op);
 229         return BinaryOperator::CreateOr(And, OpRHS);
 230       }
 231     }
 232
 233     break;
 234   case Instruction::Add:
 235     if (Op->hasOneUse()) {
 236       // Adding a one to a single bit bit-field should be turned into an XOR
 237       // of the bit.  First thing to check is to see if this AND is with a
 238       // single bit constant.
 239       const APInt &AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
 240
 241       // If there is only one bit set.
 242       if (AndRHSV.isPowerOf2()) {
 243         // Ok, at this point, we know that we are masking the result of the
 244         // ADD down to exactly one bit.  If the constant we are adding has
 245         // no bits set below this bit, then we can eliminate the ADD.
 246         const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
 247
 248         // Check to see if any bits below the one bit set in AndRHSV are set.
 249         if ((AddRHS & (AndRHSV-1)) == 0) {
 250           // If not, the only thing that can effect the output of the AND is
 251           // the bit specified by AndRHSV.  If that bit is set, the effect of
 252           // the XOR is to toggle the bit.  If it is clear, then the ADD has
 253           // no effect.
 254           if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
 255             TheAnd.setOperand(0, X);
 256             return &TheAnd;
 257           } else {
 258             // Pull the XOR out of the AND.
 259             Value *NewAnd = Builder->CreateAnd(X, AndRHS);
 260             NewAnd->takeName(Op);
 261             return BinaryOperator::CreateXor(NewAnd, AndRHS);
 262           }
 263         }
 264       }
 265     }
 266     break;
 267
 268   case Instruction::Shl: {
 269     // We know that the AND will not produce any of the bits shifted in, so if
 270     // the anded constant includes them, clear them now!
 271     //
 272     uint32_t BitWidth = AndRHS->getType()->getBitWidth();
 273     uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
 274     APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
 275     ConstantInt *CI = ConstantInt::get(AndRHS->getContext(),
 276                                        AndRHS->getValue() & ShlMask);
 277
 278     if (CI->getValue() == ShlMask)
 279       // Masking out bits that the shift already masks.
 280       return ReplaceInstUsesWith(TheAnd, Op);   // No need for the and.
 281
 282     if (CI != AndRHS) {                  // Reducing bits set in and.
 283       TheAnd.setOperand(1, CI);
 284       return &TheAnd;
 285     }
 286     break;
 287   }
 288   case Instruction::LShr: {
 289     // We know that the AND will not produce any of the bits shifted in, so if
 290     // the anded constant includes them, clear them now!  This only applies to
 291     // unsigned shifts, because a signed shr may bring in set bits!
 292     //
 293     uint32_t BitWidth = AndRHS->getType()->getBitWidth();
 294     uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
 295     APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
 296     ConstantInt *CI = ConstantInt::get(Op->getContext(),
 297                                        AndRHS->getValue() & ShrMask);
 298
 299     if (CI->getValue() == ShrMask)
 300       // Masking out bits that the shift already masks.
 301       return ReplaceInstUsesWith(TheAnd, Op);
 302
 303     if (CI != AndRHS) {
 304       TheAnd.setOperand(1, CI);  // Reduce bits set in and cst.
 305       return &TheAnd;
 306     }
 307     break;
 308   }
 309   case Instruction::AShr:
 310     // Signed shr.
 311     // See if this is shifting in some sign extension, then masking it out
 312     // with an and.
 313     if (Op->hasOneUse()) {
 314       uint32_t BitWidth = AndRHS->getType()->getBitWidth();
 315       uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
 316       APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
 317       Constant *C = ConstantInt::get(Op->getContext(),
 318                                      AndRHS->getValue() & ShrMask);
 319       if (C == AndRHS) {          // Masking out bits shifted in.
 320         // (Val ashr C1) & C2 -> (Val lshr C1) & C2
 321         // Make the argument unsigned.
 322         Value *ShVal = Op->getOperand(0);
 323         ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
 324         return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
 325       }
 326     }
 327     break;
 328   }
 329   return 0;
 330 }
 331
 332
 333 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
 334 /// true, otherwise (V < Lo || V >= Hi).  In pratice, we emit the more efficient
 335 /// (V-Lo) <u Hi-Lo.  This method expects that Lo <= Hi. isSigned indicates
 336 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
 337 /// insert new instructions.
 338 Value *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
 339                                      bool isSigned, bool Inside) {
 340   assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
 341             ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
 342          "Lo is not <= Hi in range emission code!");
 343
 344   if (Inside) {
 345     if (Lo == Hi)  // Trivially false.
 346       return ConstantInt::getFalse(V->getContext());
 347
 348     // V >= Min && V < Hi --> V < Hi
 349     if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
 350       ICmpInst::Predicate pred = (isSigned ?
 351         ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
 352       return Builder->CreateICmp(pred, V, Hi);
 353     }
 354
 355     // Emit V-Lo <u Hi-Lo
 356     Constant *NegLo = ConstantExpr::getNeg(Lo);
 357     Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
 358     Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
 359     return Builder->CreateICmpULT(Add, UpperBound);
 360   }
 361
 362   if (Lo == Hi)  // Trivially true.
 363     return ConstantInt::getTrue(V->getContext());
 364
 365   // V < Min || V >= Hi -> V > Hi-1
 366   Hi = SubOne(cast<ConstantInt>(Hi));
 367   if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
 368     ICmpInst::Predicate pred = (isSigned ?
 369         ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
 370     return Builder->CreateICmp(pred, V, Hi);
 371   }
 372
 373   // Emit V-Lo >u Hi-1-Lo
 374   // Note that Hi has already had one subtracted from it, above.
 375   ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
 376   Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
 377   Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
 378   return Builder->CreateICmpUGT(Add, LowerBound);
 379 }
 380
 381 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
 382 // any number of 0s on either side.  The 1s are allowed to wrap from LSB to
 383 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs.  0x0F0F0000 is
 384 // not, since all 1s are not contiguous.
 385 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
 386   const APInt& V = Val->getValue();
 387   uint32_t BitWidth = Val->getType()->getBitWidth();
 388   if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
 389
 390   // look for the first zero bit after the run of ones
 391   MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
 392   // look for the first non-zero bit
 393   ME = V.getActiveBits();
 394   return true;
 395 }
 396
 397 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
 398 /// where isSub determines whether the operator is a sub.  If we can fold one of
 399 /// the following xforms:
 400 ///
 401 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
 402 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
 403 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
 404 ///
 405 /// return (A +/- B).
 406 ///
 407 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
 408                                         ConstantInt *Mask, bool isSub,
 409                                         Instruction &I) {
 410   Instruction *LHSI = dyn_cast<Instruction>(LHS);
 411   if (!LHSI || LHSI->getNumOperands() != 2 ||
 412       !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
 413
 414   ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
 415
 416   switch (LHSI->getOpcode()) {
 417   default: return 0;
 418   case Instruction::And:
 419     if (ConstantExpr::getAnd(N, Mask) == Mask) {
 420       // If the AndRHS is a power of two minus one (0+1+), this is simple.
 421       if ((Mask->getValue().countLeadingZeros() +
 422            Mask->getValue().countPopulation()) ==
 423           Mask->getValue().getBitWidth())
 424         break;
 425
 426       // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
 427       // part, we don't need any explicit masks to take them out of A.  If that
 428       // is all N is, ignore it.
 429       uint32_t MB = 0, ME = 0;
 430       if (isRunOfOnes(Mask, MB, ME)) {  // begin/end bit of run, inclusive
 431         uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
 432         APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
 433         if (MaskedValueIsZero(RHS, Mask))
 434           break;
 435       }
 436     }
 437     return 0;
 438   case Instruction::Or:
 439   case Instruction::Xor:
 440     // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
 441     if ((Mask->getValue().countLeadingZeros() +
 442          Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
 443         && ConstantExpr::getAnd(N, Mask)->isNullValue())
 444       break;
 445     return 0;
 446   }
 447
 448   if (isSub)
 449     return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
 450   return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
 451 }
 452
 453 /// enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C)
 454 /// One of A and B is considered the mask, the other the value. This is
 455 /// described as the "AMask" or "BMask" part of the enum. If the enum
 456 /// contains only "Mask", then both A and B can be considered masks.
 457 /// If A is the mask, then it was proven, that (A & C) == C. This
 458 /// is trivial if C == A, or C == 0. If both A and C are constants, this
 459 /// proof is also easy.
 460 /// For the following explanations we assume that A is the mask.
 461 /// The part "AllOnes" declares, that the comparison is true only
 462 /// if (A & B) == A, or all bits of A are set in B.
 463 ///   Example: (icmp eq (A & 3), 3) -> FoldMskICmp_AMask_AllOnes
 464 /// The part "AllZeroes" declares, that the comparison is true only
 465 /// if (A & B) == 0, or all bits of A are cleared in B.
 466 ///   Example: (icmp eq (A & 3), 0) -> FoldMskICmp_Mask_AllZeroes
 467 /// The part "Mixed" declares, that (A & B) == C and C might or might not
 468 /// contain any number of one bits and zero bits.
 469 ///   Example: (icmp eq (A & 3), 1) -> FoldMskICmp_AMask_Mixed
 470 /// The Part "Not" means, that in above descriptions "==" should be replaced
 471 /// by "!=".
 472 ///   Example: (icmp ne (A & 3), 3) -> FoldMskICmp_AMask_NotAllOnes
 473 /// If the mask A contains a single bit, then the following is equivalent:
 474 ///    (icmp eq (A & B), A) equals (icmp ne (A & B), 0)
 475 ///    (icmp ne (A & B), A) equals (icmp eq (A & B), 0)
 476 enum MaskedICmpType {
 477   FoldMskICmp_AMask_AllOnes           =     1,
 478   FoldMskICmp_AMask_NotAllOnes        =     2,
 479   FoldMskICmp_BMask_AllOnes           =     4,
 480   FoldMskICmp_BMask_NotAllOnes        =     8,
 481   FoldMskICmp_Mask_AllZeroes          =    16,
 482   FoldMskICmp_Mask_NotAllZeroes       =    32,
 483   FoldMskICmp_AMask_Mixed             =    64,
 484   FoldMskICmp_AMask_NotMixed          =   128,
 485   FoldMskICmp_BMask_Mixed             =   256,
 486   FoldMskICmp_BMask_NotMixed          =   512
 487 };
 488
 489 /// return the set of pattern classes (from MaskedICmpType)
 490 /// that (icmp SCC (A & B), C) satisfies
 491 static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C,
 492                                     ICmpInst::Predicate SCC)
 493 {
 494   ConstantInt *ACst = dyn_cast<ConstantInt>(A);
 495   ConstantInt *BCst = dyn_cast<ConstantInt>(B);
 496   ConstantInt *CCst = dyn_cast<ConstantInt>(C);
 497   bool icmp_eq = (SCC == ICmpInst::ICMP_EQ);
 498   bool icmp_abit = (ACst != 0 && !ACst->isZero() &&
 499                     ACst->getValue().isPowerOf2());
 500   bool icmp_bbit = (BCst != 0 && !BCst->isZero() &&
 501                     BCst->getValue().isPowerOf2());
 502   unsigned result = 0;
 503   if (CCst != 0 && CCst->isZero()) {
 504     // if C is zero, then both A and B qualify as mask
 505     result |= (icmp_eq ? (FoldMskICmp_Mask_AllZeroes |
 506                           FoldMskICmp_Mask_AllZeroes |
 507                           FoldMskICmp_AMask_Mixed |
 508                           FoldMskICmp_BMask_Mixed)
 509                        : (FoldMskICmp_Mask_NotAllZeroes |
 510                           FoldMskICmp_Mask_NotAllZeroes |
 511                           FoldMskICmp_AMask_NotMixed |
 512                           FoldMskICmp_BMask_NotMixed));
 513     if (icmp_abit)
 514       result |= (icmp_eq ? (FoldMskICmp_AMask_NotAllOnes |
 515                             FoldMskICmp_AMask_NotMixed)
 516                          : (FoldMskICmp_AMask_AllOnes |
 517                             FoldMskICmp_AMask_Mixed));
 518     if (icmp_bbit)
 519       result |= (icmp_eq ? (FoldMskICmp_BMask_NotAllOnes |
 520                             FoldMskICmp_BMask_NotMixed)
 521                          : (FoldMskICmp_BMask_AllOnes |
 522                             FoldMskICmp_BMask_Mixed));
 523     return result;
 524   }
 525   if (A == C) {
 526     result |= (icmp_eq ? (FoldMskICmp_AMask_AllOnes |
 527                           FoldMskICmp_AMask_Mixed)
 528                        : (FoldMskICmp_AMask_NotAllOnes |
 529                           FoldMskICmp_AMask_NotMixed));
 530     if (icmp_abit)
 531       result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
 532                             FoldMskICmp_AMask_NotMixed)
 533                          : (FoldMskICmp_Mask_AllZeroes |
 534                             FoldMskICmp_AMask_Mixed));
 535   }
 536   else if (ACst != 0 && CCst != 0 &&
 537         ConstantExpr::getAnd(ACst, CCst) == CCst) {
 538     result |= (icmp_eq ? FoldMskICmp_AMask_Mixed
 539                        : FoldMskICmp_AMask_NotMixed);
 540   }
 541   if (B == C)
 542   {
 543     result |= (icmp_eq ? (FoldMskICmp_BMask_AllOnes |
 544                           FoldMskICmp_BMask_Mixed)
 545                        : (FoldMskICmp_BMask_NotAllOnes |
 546                           FoldMskICmp_BMask_NotMixed));
 547     if (icmp_bbit)
 548       result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
 549                             FoldMskICmp_BMask_NotMixed)
 550                          : (FoldMskICmp_Mask_AllZeroes |
 551                             FoldMskICmp_BMask_Mixed));
 552   }
 553   else if (BCst != 0 && CCst != 0 &&
 554         ConstantExpr::getAnd(BCst, CCst) == CCst) {
 555     result |= (icmp_eq ? FoldMskICmp_BMask_Mixed
 556                        : FoldMskICmp_BMask_NotMixed);
 557   }
 558   return result;
 559 }
 560
 561 /// foldLogOpOfMaskedICmpsHelper:
 562 /// handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
 563 /// return the set of pattern classes (from MaskedICmpType)
 564 /// that both LHS and RHS satisfy
 565 static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
 566                                              Value*& B, Value*& C,
 567                                              Value*& D, Value*& E,
 568                                              ICmpInst *LHS, ICmpInst *RHS) {
 569   ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
 570   if (LHSCC != ICmpInst::ICMP_EQ && LHSCC != ICmpInst::ICMP_NE) return 0;
 571   if (RHSCC != ICmpInst::ICMP_EQ && RHSCC != ICmpInst::ICMP_NE) return 0;
 572   if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0;
 573   // vectors are not (yet?) supported
 574   if (LHS->getOperand(0)->getType()->isVectorTy()) return 0;
 575
 576   // Here comes the tricky part:
 577   // LHS might be of the form L11 & L12 == X, X == L21 & L22,
 578   // and L11 & L12 == L21 & L22. The same goes for RHS.
 579   // Now we must find those components L** and R**, that are equal, so
 580   // that we can extract the parameters A, B, C, D, and E for the canonical
 581   // above.
 582   Value *L1 = LHS->getOperand(0);
 583   Value *L2 = LHS->getOperand(1);
 584   Value *L11,*L12,*L21,*L22;
 585   if (match(L1, m_And(m_Value(L11), m_Value(L12)))) {
 586     if (!match(L2, m_And(m_Value(L21), m_Value(L22))))
 587       L21 = L22 = 0;
 588   }
 589   else {
 590     if (!match(L2, m_And(m_Value(L11), m_Value(L12))))
 591       return 0;
 592     std::swap(L1, L2);
 593     L21 = L22 = 0;
 594   }
 595
 596   Value *R1 = RHS->getOperand(0);
 597   Value *R2 = RHS->getOperand(1);
 598   Value *R11,*R12;
 599   bool ok = false;
 600   if (match(R1, m_And(m_Value(R11), m_Value(R12)))) {
 601     if (R11 != 0 && (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22)) {
 602       A = R11; D = R12; E = R2; ok = true;
 603     }
 604     else
 605     if (R12 != 0 && (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22)) {
 606       A = R12; D = R11; E = R2; ok = true;
 607     }
 608   }
 609   if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) {
 610     if (R11 != 0 && (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22)) {
 611        A = R11; D = R12; E = R1; ok = true;
 612     }
 613     else
 614     if (R12 != 0 && (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22)) {
 615       A = R12; D = R11; E = R1; ok = true;
 616     }
 617     else
 618       return 0;
 619   }
 620   if (!ok)
 621     return 0;
 622
 623   if (L11 == A) {
 624     B = L12; C = L2;
 625   }
 626   else if (L12 == A) {
 627     B = L11; C = L2;
 628   }
 629   else if (L21 == A) {
 630     B = L22; C = L1;
 631   }
 632   else if (L22 == A) {
 633     B = L21; C = L1;
 634   }
 635
 636   unsigned left_type = getTypeOfMaskedICmp(A, B, C, LHSCC);
 637   unsigned right_type = getTypeOfMaskedICmp(A, D, E, RHSCC);
 638   return left_type & right_type;
 639 }
 640 /// foldLogOpOfMaskedICmps:
 641 /// try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
 642 /// into a single (icmp(A & X) ==/!= Y)
 643 static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
 644                                      ICmpInst::Predicate NEWCC,
 645                                      llvm::InstCombiner::BuilderTy* Builder) {
 646   Value *A = 0, *B = 0, *C = 0, *D = 0, *E = 0;
 647   unsigned mask = foldLogOpOfMaskedICmpsHelper(A, B, C, D, E, LHS, RHS);
 648   if (mask == 0) return 0;
 649
 650   if (NEWCC == ICmpInst::ICMP_NE)
 651     mask >>= 1; // treat "Not"-states as normal states
 652
 653   if (mask & FoldMskICmp_Mask_AllZeroes) {
 654     // (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
 655     // -> (icmp eq (A & (B|D)), 0)
 656     Value* newOr = Builder->CreateOr(B, D);
 657     Value* newAnd = Builder->CreateAnd(A, newOr);
 658     // we can't use C as zero, because we might actually handle
 659     //   (icmp ne (A & B), B) & (icmp ne (A & D), D)
 660     // with B and D, having a single bit set
 661     Value* zero = Constant::getNullValue(A->getType());
 662     return Builder->CreateICmp(NEWCC, newAnd, zero);
 663   }
 664   else if (mask & FoldMskICmp_BMask_AllOnes) {
 665     // (icmp eq (A & B), B) & (icmp eq (A & D), D)
 666     // -> (icmp eq (A & (B|D)), (B|D))
 667     Value* newOr = Builder->CreateOr(B, D);
 668     Value* newAnd = Builder->CreateAnd(A, newOr);
 669     return Builder->CreateICmp(NEWCC, newAnd, newOr);
 670   }
 671   else if (mask & FoldMskICmp_AMask_AllOnes) {
 672     // (icmp eq (A & B), A) & (icmp eq (A & D), A)
 673     // -> (icmp eq (A & (B&D)), A)
 674     Value* newAnd1 = Builder->CreateAnd(B, D);
 675     Value* newAnd = Builder->CreateAnd(A, newAnd1);
 676     return Builder->CreateICmp(NEWCC, newAnd, A);
 677   }
 678   else if (mask & FoldMskICmp_BMask_Mixed) {
 679     // (icmp eq (A & B), C) & (icmp eq (A & D), E)
 680     // We already know that B & C == C && D & E == E.
 681     // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
 682     // C and E, which are shared by both the mask B and the mask D, don't
 683     // contradict, then we can transform to
 684     // -> (icmp eq (A & (B|D)), (C|E))
 685     // Currently, we only handle the case of B, C, D, and E being constant.
 686     ConstantInt *BCst = dyn_cast<ConstantInt>(B);
 687     if (BCst == 0) return 0;
 688     ConstantInt *DCst = dyn_cast<ConstantInt>(D);
 689     if (DCst == 0) return 0;
 690     // we can't simply use C and E, because we might actually handle
 691     //   (icmp ne (A & B), B) & (icmp eq (A & D), D)
 692     // with B and D, having a single bit set
 693
 694     ConstantInt *CCst = dyn_cast<ConstantInt>(C);
 695     if (CCst == 0) return 0;
 696     if (LHS->getPredicate() != NEWCC)
 697       CCst = dyn_cast<ConstantInt>( ConstantExpr::getXor(BCst, CCst) );
 698     ConstantInt *ECst = dyn_cast<ConstantInt>(E);
 699     if (ECst == 0) return 0;
 700     if (RHS->getPredicate() != NEWCC)
 701       ECst = dyn_cast<ConstantInt>( ConstantExpr::getXor(DCst, ECst) );
 702     ConstantInt* MCst = dyn_cast<ConstantInt>(
 703       ConstantExpr::getAnd(ConstantExpr::getAnd(BCst, DCst),
 704                            ConstantExpr::getXor(CCst, ECst)) );
 705     // if there is a conflict we should actually return a false for the
 706     // whole construct
 707     if (!MCst->isZero())
 708       return 0;
 709     Value *newOr1 = Builder->CreateOr(B, D);
 710     Value *newOr2 = ConstantExpr::getOr(CCst, ECst);
 711     Value *newAnd = Builder->CreateAnd(A, newOr1);
 712     return Builder->CreateICmp(NEWCC, newAnd, newOr2);
 713   }
 714   return 0;
 715 }
 716
 717 /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
 718 Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
 719   ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
 720
 721   // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
 722   if (PredicatesFoldable(LHSCC, RHSCC)) {
 723     if (LHS->getOperand(0) == RHS->getOperand(1) &&
 724         LHS->getOperand(1) == RHS->getOperand(0))
 725       LHS->swapOperands();
 726     if (LHS->getOperand(0) == RHS->getOperand(0) &&
 727         LHS->getOperand(1) == RHS->getOperand(1)) {
 728       Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
 729       unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
 730       bool isSigned = LHS->isSigned() || RHS->isSigned();
 731       return getICmpValue(isSigned, Code, Op0, Op1, Builder);
 732     }
 733   }
 734
 735   // handle (roughly):  (icmp eq (A & B), C) & (icmp eq (A & D), E)
 736   if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_EQ, Builder))
 737     return V;
 738
 739   // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
 740   Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
 741   ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
 742   ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
 743   if (LHSCst == 0 || RHSCst == 0) return 0;
 744
 745   if (LHSCst == RHSCst && LHSCC == RHSCC) {
 746     // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
 747     // where C is a power of 2
 748     if (LHSCC == ICmpInst::ICMP_ULT &&
 749         LHSCst->getValue().isPowerOf2()) {
 750       Value *NewOr = Builder->CreateOr(Val, Val2);
 751       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
 752     }
 753
 754     // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
 755     if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
 756       Value *NewOr = Builder->CreateOr(Val, Val2);
 757       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
 758     }
 759
 760     // (icmp slt A, 0) & (icmp slt B, 0) --> (icmp slt (A&B), 0)
 761     if (LHSCC == ICmpInst::ICMP_SLT && LHSCst->isZero()) {
 762       Value *NewAnd = Builder->CreateAnd(Val, Val2);
 763       return Builder->CreateICmp(LHSCC, NewAnd, LHSCst);
 764     }
 765
 766     // (icmp sgt A, -1) & (icmp sgt B, -1) --> (icmp sgt (A|B), -1)
 767     if (LHSCC == ICmpInst::ICMP_SGT && LHSCst->isAllOnesValue()) {
 768       Value *NewOr = Builder->CreateOr(Val, Val2);
 769       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
 770     }
 771   }
 772
 773   // From here on, we only handle:
 774   //    (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
 775   if (Val != Val2) return 0;
 776
 777   // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
 778   if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
 779       RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
 780       LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
 781       RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
 782     return 0;
 783
 784   // Make a constant range that's the intersection of the two icmp ranges.
 785   // If the intersection is empty, we know that the result is false.
 786   ConstantRange LHSRange =
 787     ConstantRange::makeICmpRegion(LHSCC, LHSCst->getValue());
 788   ConstantRange RHSRange =
 789     ConstantRange::makeICmpRegion(RHSCC, RHSCst->getValue());
 790
 791   if (LHSRange.intersectWith(RHSRange).isEmptySet())
 792     return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
 793
 794   // We can't fold (ugt x, C) & (sgt x, C2).
 795   if (!PredicatesFoldable(LHSCC, RHSCC))
 796     return 0;
 797
 798   // Ensure that the larger constant is on the RHS.
 799   bool ShouldSwap;
 800   if (CmpInst::isSigned(LHSCC) ||
 801       (ICmpInst::isEquality(LHSCC) &&
 802        CmpInst::isSigned(RHSCC)))
 803     ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
 804   else
 805     ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
 806
 807   if (ShouldSwap) {
 808     std::swap(LHS, RHS);
 809     std::swap(LHSCst, RHSCst);
 810     std::swap(LHSCC, RHSCC);
 811   }
 812
 813   // At this point, we know we have two icmp instructions
 814   // comparing a value against two constants and and'ing the result
 815   // together.  Because of the above check, we know that we only have
 816   // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
 817   // (from the icmp folding check above), that the two constants
 818   // are not equal and that the larger constant is on the RHS
 819   assert(LHSCst != RHSCst && "Compares not folded above?");
 820
 821   switch (LHSCC) {
 822   default: llvm_unreachable("Unknown integer condition code!");
 823   case ICmpInst::ICMP_EQ:
 824     switch (RHSCC) {
 825     default: llvm_unreachable("Unknown integer condition code!");
 826     case ICmpInst::ICMP_NE:         // (X == 13 & X != 15) -> X == 13
 827     case ICmpInst::ICMP_ULT:        // (X == 13 & X <  15) -> X == 13
 828     case ICmpInst::ICMP_SLT:        // (X == 13 & X <  15) -> X == 13
 829       return LHS;
 830     }
 831   case ICmpInst::ICMP_NE:
 832     switch (RHSCC) {
 833     default: llvm_unreachable("Unknown integer condition code!");
 834     case ICmpInst::ICMP_ULT:
 835       if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
 836         return Builder->CreateICmpULT(Val, LHSCst);
 837       break;                        // (X != 13 & X u< 15) -> no change
 838     case ICmpInst::ICMP_SLT:
 839       if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
 840         return Builder->CreateICmpSLT(Val, LHSCst);
 841       break;                        // (X != 13 & X s< 15) -> no change
 842     case ICmpInst::ICMP_EQ:         // (X != 13 & X == 15) -> X == 15
 843     case ICmpInst::ICMP_UGT:        // (X != 13 & X u> 15) -> X u> 15
 844     case ICmpInst::ICMP_SGT:        // (X != 13 & X s> 15) -> X s> 15
 845       return RHS;
 846     case ICmpInst::ICMP_NE:
 847       if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
 848         Constant *AddCST = ConstantExpr::getNeg(LHSCst);
 849         Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
 850         return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1));
 851       }
 852       break;                        // (X != 13 & X != 15) -> no change
 853     }
 854     break;
 855   case ICmpInst::ICMP_ULT:
 856     switch (RHSCC) {
 857     default: llvm_unreachable("Unknown integer condition code!");
 858     case ICmpInst::ICMP_EQ:         // (X u< 13 & X == 15) -> false
 859     case ICmpInst::ICMP_UGT:        // (X u< 13 & X u> 15) -> false
 860       return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
 861     case ICmpInst::ICMP_SGT:        // (X u< 13 & X s> 15) -> no change
 862       break;
 863     case ICmpInst::ICMP_NE:         // (X u< 13 & X != 15) -> X u< 13
 864     case ICmpInst::ICMP_ULT:        // (X u< 13 & X u< 15) -> X u< 13
 865       return LHS;
 866     case ICmpInst::ICMP_SLT:        // (X u< 13 & X s< 15) -> no change
 867       break;
 868     }
 869     break;
 870   case ICmpInst::ICMP_SLT:
 871     switch (RHSCC) {
 872     default: llvm_unreachable("Unknown integer condition code!");
 873     case ICmpInst::ICMP_UGT:        // (X s< 13 & X u> 15) -> no change
 874       break;
 875     case ICmpInst::ICMP_NE:         // (X s< 13 & X != 15) -> X < 13
 876     case ICmpInst::ICMP_SLT:        // (X s< 13 & X s< 15) -> X < 13
 877       return LHS;
 878     case ICmpInst::ICMP_ULT:        // (X s< 13 & X u< 15) -> no change
 879       break;
 880     }
 881     break;
 882   case ICmpInst::ICMP_UGT:
 883     switch (RHSCC) {
 884     default: llvm_unreachable("Unknown integer condition code!");
 885     case ICmpInst::ICMP_EQ:         // (X u> 13 & X == 15) -> X == 15
 886     case ICmpInst::ICMP_UGT:        // (X u> 13 & X u> 15) -> X u> 15
 887       return RHS;
 888     case ICmpInst::ICMP_SGT:        // (X u> 13 & X s> 15) -> no change
 889       break;
 890     case ICmpInst::ICMP_NE:
 891       if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
 892         return Builder->CreateICmp(LHSCC, Val, RHSCst);
 893       break;                        // (X u> 13 & X != 15) -> no change
 894     case ICmpInst::ICMP_ULT:        // (X u> 13 & X u< 15) -> (X-14) <u 1
 895       return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true);
 896     case ICmpInst::ICMP_SLT:        // (X u> 13 & X s< 15) -> no change
 897       break;
 898     }
 899     break;
 900   case ICmpInst::ICMP_SGT:
 901     switch (RHSCC) {
 902     default: llvm_unreachable("Unknown integer condition code!");
 903     case ICmpInst::ICMP_EQ:         // (X s> 13 & X == 15) -> X == 15
 904     case ICmpInst::ICMP_SGT:        // (X s> 13 & X s> 15) -> X s> 15
 905       return RHS;
 906     case ICmpInst::ICMP_UGT:        // (X s> 13 & X u> 15) -> no change
 907       break;
 908     case ICmpInst::ICMP_NE:
 909       if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
 910         return Builder->CreateICmp(LHSCC, Val, RHSCst);
 911       break;                        // (X s> 13 & X != 15) -> no change
 912     case ICmpInst::ICMP_SLT:        // (X s> 13 & X s< 15) -> (X-14) s< 1
 913       return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true);
 914     case ICmpInst::ICMP_ULT:        // (X s> 13 & X u< 15) -> no change
 915       break;
 916     }
 917     break;
 918   }
 919
 920   return 0;
 921 }
 922
 923 /// FoldAndOfFCmps - Optimize (fcmp)&(fcmp).  NOTE: Unlike the rest of
 924 /// instcombine, this returns a Value which should already be inserted into the
 925 /// function.
 926 Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
 927   if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
 928       RHS->getPredicate() == FCmpInst::FCMP_ORD) {
 929     // (fcmp ord x, c) & (fcmp ord y, c)  -> (fcmp ord x, y)
 930     if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
 931       if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
 932         // If either of the constants are nans, then the whole thing returns
 933         // false.
 934         if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
 935           return ConstantInt::getFalse(LHS->getContext());
 936         return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
 937       }
 938
 939     // Handle vector zeros.  This occurs because the canonical form of
 940     // "fcmp ord x,x" is "fcmp ord x, 0".
 941     if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
 942         isa<ConstantAggregateZero>(RHS->getOperand(1)))
 943       return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
 944     return 0;
 945   }
 946
 947   Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
 948   Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
 949   FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
 950
 951
 952   if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
 953     // Swap RHS operands to match LHS.
 954     Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
 955     std::swap(Op1LHS, Op1RHS);
 956   }
 957
 958   if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
 959     // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
 960     if (Op0CC == Op1CC)
 961       return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
 962     if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
 963       return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
 964     if (Op0CC == FCmpInst::FCMP_TRUE)
 965       return RHS;
 966     if (Op1CC == FCmpInst::FCMP_TRUE)
 967       return LHS;
 968
 969     bool Op0Ordered;
 970     bool Op1Ordered;
 971     unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
 972     unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
 973     if (Op1Pred == 0) {
 974       std::swap(LHS, RHS);
 975       std::swap(Op0Pred, Op1Pred);
 976       std::swap(Op0Ordered, Op1Ordered);
 977     }
 978     if (Op0Pred == 0) {
 979       // uno && ueq -> uno && (uno || eq) -> ueq
 980       // ord && olt -> ord && (ord && lt) -> olt
 981       if (Op0Ordered == Op1Ordered)
 982         return RHS;
 983
 984       // uno && oeq -> uno && (ord && eq) -> false
 985       // uno && ord -> false
 986       if (!Op0Ordered)
 987         return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
 988       // ord && ueq -> ord && (uno || eq) -> oeq
 989       return getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS, Builder);
 990     }
 991   }
 992
 993   return 0;
 994 }
 995
 996
 997 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
 998   bool Changed = SimplifyAssociativeOrCommutative(I);
 999   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1000
1001   if (Value *V = SimplifyAndInst(Op0, Op1, TD))
1002     return ReplaceInstUsesWith(I, V);
1003
1004   // (A|B)&(A|C) -> A|(B&C) etc
1005   if (Value *V = SimplifyUsingDistributiveLaws(I))
1006     return ReplaceInstUsesWith(I, V);
1007
1008   // See if we can simplify any instructions used by the instruction whose sole
1009   // purpose is to compute bits we don't care about.
1010   if (SimplifyDemandedInstructionBits(I))
1011     return &I;
1012
1013   if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
1014     const APInt &AndRHSMask = AndRHS->getValue();
1015
1016     // Optimize a variety of ((val OP C1) & C2) combinations...
1017     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1018       Value *Op0LHS = Op0I->getOperand(0);
1019       Value *Op0RHS = Op0I->getOperand(1);
1020       switch (Op0I->getOpcode()) {
1021       default: break;
1022       case Instruction::Xor:
1023       case Instruction::Or: {
1024         // If the mask is only needed on one incoming arm, push it up.
1025         if (!Op0I->hasOneUse()) break;
1026
1027         APInt NotAndRHS(~AndRHSMask);
1028         if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1029           // Not masking anything out for the LHS, move to RHS.
1030           Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
1031                                              Op0RHS->getName()+".masked");
1032           return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
1033         }
1034         if (!isa<Constant>(Op0RHS) &&
1035             MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1036           // Not masking anything out for the RHS, move to LHS.
1037           Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
1038                                              Op0LHS->getName()+".masked");
1039           return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
1040         }
1041
1042         break;
1043       }
1044       case Instruction::Add:
1045         // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1046         // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1047         // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1048         if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1049           return BinaryOperator::CreateAnd(V, AndRHS);
1050         if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1051           return BinaryOperator::CreateAnd(V, AndRHS);  // Add commutes
1052         break;
1053
1054       case Instruction::Sub:
1055         // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1056         // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1057         // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1058         if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1059           return BinaryOperator::CreateAnd(V, AndRHS);
1060
1061         // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
1062         // has 1's for all bits that the subtraction with A might affect.
1063         if (Op0I->hasOneUse() && !match(Op0LHS, m_Zero())) {
1064           uint32_t BitWidth = AndRHSMask.getBitWidth();
1065           uint32_t Zeros = AndRHSMask.countLeadingZeros();
1066           APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
1067
1068           if (MaskedValueIsZero(Op0LHS, Mask)) {
1069             Value *NewNeg = Builder->CreateNeg(Op0RHS);
1070             return BinaryOperator::CreateAnd(NewNeg, AndRHS);
1071           }
1072         }
1073         break;
1074
1075       case Instruction::Shl:
1076       case Instruction::LShr:
1077         // (1 << x) & 1 --> zext(x == 0)
1078         // (1 >> x) & 1 --> zext(x == 0)
1079         if (AndRHSMask == 1 && Op0LHS == AndRHS) {
1080           Value *NewICmp =
1081             Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
1082           return new ZExtInst(NewICmp, I.getType());
1083         }
1084         break;
1085       }
1086
1087       if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1088         if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1089           return Res;
1090     }
1091
1092     // If this is an integer truncation, and if the source is an 'and' with
1093     // immediate, transform it.  This frequently occurs for bitfield accesses.
1094     {
1095       Value *X = 0; ConstantInt *YC = 0;
1096       if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) {
1097         // Change: and (trunc (and X, YC) to T), C2
1098         // into  : and (trunc X to T), trunc(YC) & C2
1099         // This will fold the two constants together, which may allow
1100         // other simplifications.
1101         Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk");
1102         Constant *C3 = ConstantExpr::getTrunc(YC, I.getType());
1103         C3 = ConstantExpr::getAnd(C3, AndRHS);
1104         return BinaryOperator::CreateAnd(NewCast, C3);
1105       }
1106     }
1107
1108     // Try to fold constant and into select arguments.
1109     if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1110       if (Instruction *R = FoldOpIntoSelect(I, SI))
1111         return R;
1112     if (isa<PHINode>(Op0))
1113       if (Instruction *NV = FoldOpIntoPhi(I))
1114         return NV;
1115   }
1116
1117
1118   // (~A & ~B) == (~(A | B)) - De Morgan's Law
1119   if (Value *Op0NotVal = dyn_castNotVal(Op0))
1120     if (Value *Op1NotVal = dyn_castNotVal(Op1))
1121       if (Op0->hasOneUse() && Op1->hasOneUse()) {
1122         Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
1123                                       I.getName()+".demorgan");
1124         return BinaryOperator::CreateNot(Or);
1125       }
1126
1127   {
1128     Value *A = 0, *B = 0, *C = 0, *D = 0;
1129     // (A|B) & ~(A&B) -> A^B
1130     if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1131         match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
1132         ((A == C && B == D) || (A == D && B == C)))
1133       return BinaryOperator::CreateXor(A, B);
1134
1135     // ~(A&B) & (A|B) -> A^B
1136     if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1137         match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
1138         ((A == C && B == D) || (A == D && B == C)))
1139       return BinaryOperator::CreateXor(A, B);
1140
1141     if (Op0->hasOneUse() &&
1142         match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
1143       if (A == Op1) {                                // (A^B)&A -> A&(A^B)
1144         I.swapOperands();     // Simplify below
1145         std::swap(Op0, Op1);
1146       } else if (B == Op1) {                         // (A^B)&B -> B&(B^A)
1147         cast<BinaryOperator>(Op0)->swapOperands();
1148         I.swapOperands();     // Simplify below
1149         std::swap(Op0, Op1);
1150       }
1151     }
1152
1153     if (Op1->hasOneUse() &&
1154         match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
1155       if (B == Op0) {                                // B&(A^B) -> B&(B^A)
1156         cast<BinaryOperator>(Op1)->swapOperands();
1157         std::swap(A, B);
1158       }
1159       // Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if
1160       // A is originally -1 (or a vector of -1 and undefs), then we enter
1161       // an endless loop. By checking that A is non-constant we ensure that
1162       // we will never get to the loop.
1163       if (A == Op0 && !isa<Constant>(A)) // A&(A^B) -> A & ~B
1164         return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
1165     }
1166
1167     // (A&((~A)|B)) -> A&B
1168     if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
1169         match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
1170       return BinaryOperator::CreateAnd(A, Op1);
1171     if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
1172         match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
1173       return BinaryOperator::CreateAnd(A, Op0);
1174   }
1175
1176   if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1))
1177     if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
1178       if (Value *Res = FoldAndOfICmps(LHS, RHS))
1179         return ReplaceInstUsesWith(I, Res);
1180
1181   // If and'ing two fcmp, try combine them into one.
1182   if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
1183     if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
1184       if (Value *Res = FoldAndOfFCmps(LHS, RHS))
1185         return ReplaceInstUsesWith(I, Res);
1186
1187
1188   // fold (and (cast A), (cast B)) -> (cast (and A, B))
1189   if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
1190     if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) {
1191       const Type *SrcTy = Op0C->getOperand(0)->getType();
1192       if (Op0C->getOpcode() == Op1C->getOpcode() && // same cast kind ?
1193           SrcTy == Op1C->getOperand(0)->getType() &&
1194           SrcTy->isIntOrIntVectorTy()) {
1195         Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0);
1196
1197         // Only do this if the casts both really cause code to be generated.
1198         if (ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
1199             ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
1200           Value *NewOp = Builder->CreateAnd(Op0COp, Op1COp, I.getName());
1201           return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
1202         }
1203
1204         // If this is and(cast(icmp), cast(icmp)), try to fold this even if the
1205         // cast is otherwise not optimizable.  This happens for vector sexts.
1206         if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
1207           if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
1208             if (Value *Res = FoldAndOfICmps(LHS, RHS))
1209               return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
1210
1211         // If this is and(cast(fcmp), cast(fcmp)), try to fold this even if the
1212         // cast is otherwise not optimizable.  This happens for vector sexts.
1213         if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
1214           if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
1215             if (Value *Res = FoldAndOfFCmps(LHS, RHS))
1216               return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
1217       }
1218     }
1219
1220   // (X >> Z) & (Y >> Z)  -> (X&Y) >> Z  for all shifts.
1221   if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
1222     if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
1223       if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
1224           SI0->getOperand(1) == SI1->getOperand(1) &&
1225           (SI0->hasOneUse() || SI1->hasOneUse())) {
1226         Value *NewOp =
1227           Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
1228                              SI0->getName());
1229         return BinaryOperator::Create(SI1->getOpcode(), NewOp,
1230                                       SI1->getOperand(1));
1231       }
1232   }
1233
1234   return Changed ? &I : 0;
1235 }
1236
1237 /// CollectBSwapParts - Analyze the specified subexpression and see if it is
1238 /// capable of providing pieces of a bswap.  The subexpression provides pieces
1239 /// of a bswap if it is proven that each of the non-zero bytes in the output of
1240 /// the expression came from the corresponding "byte swapped" byte in some other
1241 /// value.  For example, if the current subexpression is "(shl i32 %X, 24)" then
1242 /// we know that the expression deposits the low byte of %X into the high byte
1243 /// of the bswap result and that all other bytes are zero.  This expression is
1244 /// accepted, the high byte of ByteValues is set to X to indicate a correct
1245 /// match.
1246 ///
1247 /// This function returns true if the match was unsuccessful and false if so.
1248 /// On entry to the function the "OverallLeftShift" is a signed integer value
1249 /// indicating the number of bytes that the subexpression is later shifted.  For
1250 /// example, if the expression is later right shifted by 16 bits, the
1251 /// OverallLeftShift value would be -2 on entry.  This is used to specify which
1252 /// byte of ByteValues is actually being set.
1253 ///
1254 /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
1255 /// byte is masked to zero by a user.  For example, in (X & 255), X will be
1256 /// processed with a bytemask of 1.  Because bytemask is 32-bits, this limits
1257 /// this function to working on up to 32-byte (256 bit) values.  ByteMask is
1258 /// always in the local (OverallLeftShift) coordinate space.
1259 ///
1260 static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
1261                               SmallVector<Value*, 8> &ByteValues) {
1262   if (Instruction *I = dyn_cast<Instruction>(V)) {
1263     // If this is an or instruction, it may be an inner node of the bswap.
1264     if (I->getOpcode() == Instruction::Or) {
1265       return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1266                                ByteValues) ||
1267              CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
1268                                ByteValues);
1269     }
1270
1271     // If this is a logical shift by a constant multiple of 8, recurse with
1272     // OverallLeftShift and ByteMask adjusted.
1273     if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
1274       unsigned ShAmt =
1275         cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
1276       // Ensure the shift amount is defined and of a byte value.
1277       if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
1278         return true;
1279
1280       unsigned ByteShift = ShAmt >> 3;
1281       if (I->getOpcode() == Instruction::Shl) {
1282         // X << 2 -> collect(X, +2)
1283         OverallLeftShift += ByteShift;
1284         ByteMask >>= ByteShift;
1285       } else {
1286         // X >>u 2 -> collect(X, -2)
1287         OverallLeftShift -= ByteShift;
1288         ByteMask <<= ByteShift;
1289         ByteMask &= (~0U >> (32-ByteValues.size()));
1290       }
1291
1292       if (OverallLeftShift >= (int)ByteValues.size()) return true;
1293       if (OverallLeftShift <= -(int)ByteValues.size()) return true;
1294
1295       return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1296                                ByteValues);
1297     }
1298
1299     // If this is a logical 'and' with a mask that clears bytes, clear the
1300     // corresponding bytes in ByteMask.
1301     if (I->getOpcode() == Instruction::And &&
1302         isa<ConstantInt>(I->getOperand(1))) {
1303       // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
1304       unsigned NumBytes = ByteValues.size();
1305       APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
1306       const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
1307
1308       for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
1309         // If this byte is masked out by a later operation, we don't care what
1310         // the and mask is.
1311         if ((ByteMask & (1 << i)) == 0)
1312           continue;
1313
1314         // If the AndMask is all zeros for this byte, clear the bit.
1315         APInt MaskB = AndMask & Byte;
1316         if (MaskB == 0) {
1317           ByteMask &= ~(1U << i);
1318           continue;
1319         }
1320
1321         // If the AndMask is not all ones for this byte, it's not a bytezap.
1322         if (MaskB != Byte)
1323           return true;
1324
1325         // Otherwise, this byte is kept.
1326       }
1327
1328       return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1329                                ByteValues);
1330     }
1331   }
1332
1333   // Okay, we got to something that isn't a shift, 'or' or 'and'.  This must be
1334   // the input value to the bswap.  Some observations: 1) if more than one byte
1335   // is demanded from this input, then it could not be successfully assembled
1336   // into a byteswap.  At least one of the two bytes would not be aligned with
1337   // their ultimate destination.
1338   if (!isPowerOf2_32(ByteMask)) return true;
1339   unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
1340
1341   // 2) The input and ultimate destinations must line up: if byte 3 of an i32
1342   // is demanded, it needs to go into byte 0 of the result.  This means that the
1343   // byte needs to be shifted until it lands in the right byte bucket.  The
1344   // shift amount depends on the position: if the byte is coming from the high
1345   // part of the value (e.g. byte 3) then it must be shifted right.  If from the
1346   // low part, it must be shifted left.
1347   unsigned DestByteNo = InputByteNo + OverallLeftShift;
1348   if (InputByteNo < ByteValues.size()/2) {
1349     if (ByteValues.size()-1-DestByteNo != InputByteNo)
1350       return true;
1351   } else {
1352     if (ByteValues.size()-1-DestByteNo != InputByteNo)
1353       return true;
1354   }
1355
1356   // If the destination byte value is already defined, the values are or'd
1357   // together, which isn't a bswap (unless it's an or of the same bits).
1358   if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
1359     return true;
1360   ByteValues[DestByteNo] = V;
1361   return false;
1362 }
1363
1364 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
1365 /// If so, insert the new bswap intrinsic and return it.
1366 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
1367   const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
1368   if (!ITy || ITy->getBitWidth() % 16 ||
1369       // ByteMask only allows up to 32-byte values.
1370       ITy->getBitWidth() > 32*8)
1371     return 0;   // Can only bswap pairs of bytes.  Can't do vectors.
1372
1373   /// ByteValues - For each byte of the result, we keep track of which value
1374   /// defines each byte.
1375   SmallVector<Value*, 8> ByteValues;
1376   ByteValues.resize(ITy->getBitWidth()/8);
1377
1378   // Try to find all the pieces corresponding to the bswap.
1379   uint32_t ByteMask = ~0U >> (32-ByteValues.size());
1380   if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
1381     return 0;
1382
1383   // Check to see if all of the bytes come from the same value.
1384   Value *V = ByteValues[0];
1385   if (V == 0) return 0;  // Didn't find a byte?  Must be zero.
1386
1387   // Check to make sure that all of the bytes come from the same value.
1388   for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
1389     if (ByteValues[i] != V)
1390       return 0;
1391   const Type *Tys[] = { ITy };
1392   Module *M = I.getParent()->getParent()->getParent();
1393   Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
1394   return CallInst::Create(F, V);
1395 }
1396
1397 /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D).  Check
1398 /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
1399 /// we can simplify this expression to "cond ? C : D or B".
1400 static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
1401                                          Value *C, Value *D) {
1402   // If A is not a select of -1/0, this cannot match.
1403   Value *Cond = 0;
1404   if (!match(A, m_SExt(m_Value(Cond))) ||
1405       !Cond->getType()->isIntegerTy(1))
1406     return 0;
1407
1408   // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
1409   if (match(D, m_Not(m_SExt(m_Specific(Cond)))))
1410     return SelectInst::Create(Cond, C, B);
1411   if (match(D, m_SExt(m_Not(m_Specific(Cond)))))
1412     return SelectInst::Create(Cond, C, B);
1413
1414   // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
1415   if (match(B, m_Not(m_SExt(m_Specific(Cond)))))
1416     return SelectInst::Create(Cond, C, D);
1417   if (match(B, m_SExt(m_Not(m_Specific(Cond)))))
1418     return SelectInst::Create(Cond, C, D);
1419   return 0;
1420 }
1421
1422 /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
1423 Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
1424   ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
1425
1426   // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
1427   if (PredicatesFoldable(LHSCC, RHSCC)) {
1428     if (LHS->getOperand(0) == RHS->getOperand(1) &&
1429         LHS->getOperand(1) == RHS->getOperand(0))
1430       LHS->swapOperands();
1431     if (LHS->getOperand(0) == RHS->getOperand(0) &&
1432         LHS->getOperand(1) == RHS->getOperand(1)) {
1433       Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
1434       unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
1435       bool isSigned = LHS->isSigned() || RHS->isSigned();
1436       return getICmpValue(isSigned, Code, Op0, Op1, Builder);
1437     }
1438   }
1439
1440   // handle (roughly):
1441   // (icmp ne (A & B), C) | (icmp ne (A & D), E)
1442   if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_NE, Builder))
1443     return V;
1444
1445   // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
1446   Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
1447   ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
1448   ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
1449   if (LHSCst == 0 || RHSCst == 0) return 0;
1450
1451   if (LHSCst == RHSCst && LHSCC == RHSCC) {
1452     // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
1453     if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
1454       Value *NewOr = Builder->CreateOr(Val, Val2);
1455       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
1456     }
1457
1458     // (icmp slt A, 0) | (icmp slt B, 0) --> (icmp slt (A|B), 0)
1459     if (LHSCC == ICmpInst::ICMP_SLT && LHSCst->isZero()) {
1460       Value *NewOr = Builder->CreateOr(Val, Val2);
1461       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
1462     }
1463
1464     // (icmp sgt A, -1) | (icmp sgt B, -1) --> (icmp sgt (A&B), -1)
1465     if (LHSCC == ICmpInst::ICMP_SGT && LHSCst->isAllOnesValue()) {
1466       Value *NewAnd = Builder->CreateAnd(Val, Val2);
1467       return Builder->CreateICmp(LHSCC, NewAnd, LHSCst);
1468     }
1469   }
1470
1471   // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1)
1472   //   iff C2 + CA == C1.
1473   if (LHSCC == ICmpInst::ICMP_ULT && RHSCC == ICmpInst::ICMP_EQ) {
1474     ConstantInt *AddCst;
1475     if (match(Val, m_Add(m_Specific(Val2), m_ConstantInt(AddCst))))
1476       if (RHSCst->getValue() + AddCst->getValue() == LHSCst->getValue())
1477         return Builder->CreateICmpULE(Val, LHSCst);
1478   }
1479
1480   // From here on, we only handle:
1481   //    (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
1482   if (Val != Val2) return 0;
1483
1484   // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
1485   if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
1486       RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
1487       LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
1488       RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
1489     return 0;
1490
1491   // We can't fold (ugt x, C) | (sgt x, C2).
1492   if (!PredicatesFoldable(LHSCC, RHSCC))
1493     return 0;
1494
1495   // Ensure that the larger constant is on the RHS.
1496   bool ShouldSwap;
1497   if (CmpInst::isSigned(LHSCC) ||
1498       (ICmpInst::isEquality(LHSCC) &&
1499        CmpInst::isSigned(RHSCC)))
1500     ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
1501   else
1502     ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
1503
1504   if (ShouldSwap) {
1505     std::swap(LHS, RHS);
1506     std::swap(LHSCst, RHSCst);
1507     std::swap(LHSCC, RHSCC);
1508   }
1509
1510   // At this point, we know we have two icmp instructions
1511   // comparing a value against two constants and or'ing the result
1512   // together.  Because of the above check, we know that we only have
1513   // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
1514   // icmp folding check above), that the two constants are not
1515   // equal.
1516   assert(LHSCst != RHSCst && "Compares not folded above?");
1517
1518   switch (LHSCC) {
1519   default: llvm_unreachable("Unknown integer condition code!");
1520   case ICmpInst::ICMP_EQ:
1521     switch (RHSCC) {
1522     default: llvm_unreachable("Unknown integer condition code!");
1523     case ICmpInst::ICMP_EQ:
1524       if (LHSCst == SubOne(RHSCst)) {
1525         // (X == 13 | X == 14) -> X-13 <u 2
1526         Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1527         Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
1528         AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1529         return Builder->CreateICmpULT(Add, AddCST);
1530       }
1531       break;                         // (X == 13 | X == 15) -> no change
1532     case ICmpInst::ICMP_UGT:         // (X == 13 | X u> 14) -> no change
1533     case ICmpInst::ICMP_SGT:         // (X == 13 | X s> 14) -> no change
1534       break;
1535     case ICmpInst::ICMP_NE:          // (X == 13 | X != 15) -> X != 15
1536     case ICmpInst::ICMP_ULT:         // (X == 13 | X u< 15) -> X u< 15
1537     case ICmpInst::ICMP_SLT:         // (X == 13 | X s< 15) -> X s< 15
1538       return RHS;
1539     }
1540     break;
1541   case ICmpInst::ICMP_NE:
1542     switch (RHSCC) {
1543     default: llvm_unreachable("Unknown integer condition code!");
1544     case ICmpInst::ICMP_EQ:          // (X != 13 | X == 15) -> X != 13
1545     case ICmpInst::ICMP_UGT:         // (X != 13 | X u> 15) -> X != 13
1546     case ICmpInst::ICMP_SGT:         // (X != 13 | X s> 15) -> X != 13
1547       return LHS;
1548     case ICmpInst::ICMP_NE:          // (X != 13 | X != 15) -> true
1549     case ICmpInst::ICMP_ULT:         // (X != 13 | X u< 15) -> true
1550     case ICmpInst::ICMP_SLT:         // (X != 13 | X s< 15) -> true
1551       return ConstantInt::getTrue(LHS->getContext());
1552     }
1553     break;
1554   case ICmpInst::ICMP_ULT:
1555     switch (RHSCC) {
1556     default: llvm_unreachable("Unknown integer condition code!");
1557     case ICmpInst::ICMP_EQ:         // (X u< 13 | X == 14) -> no change
1558       break;
1559     case ICmpInst::ICMP_UGT:        // (X u< 13 | X u> 15) -> (X-13) u> 2
1560       // If RHSCst is [us]MAXINT, it is always false.  Not handling
1561       // this can cause overflow.
1562       if (RHSCst->isMaxValue(false))
1563         return LHS;
1564       return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false);
1565     case ICmpInst::ICMP_SGT:        // (X u< 13 | X s> 15) -> no change
1566       break;
1567     case ICmpInst::ICMP_NE:         // (X u< 13 | X != 15) -> X != 15
1568     case ICmpInst::ICMP_ULT:        // (X u< 13 | X u< 15) -> X u< 15
1569       return RHS;
1570     case ICmpInst::ICMP_SLT:        // (X u< 13 | X s< 15) -> no change
1571       break;
1572     }
1573     break;
1574   case ICmpInst::ICMP_SLT:
1575     switch (RHSCC) {
1576     default: llvm_unreachable("Unknown integer condition code!");
1577     case ICmpInst::ICMP_EQ:         // (X s< 13 | X == 14) -> no change
1578       break;
1579     case ICmpInst::ICMP_SGT:        // (X s< 13 | X s> 15) -> (X-13) s> 2
1580       // If RHSCst is [us]MAXINT, it is always false.  Not handling
1581       // this can cause overflow.
1582       if (RHSCst->isMaxValue(true))
1583         return LHS;
1584       return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false);
1585     case ICmpInst::ICMP_UGT:        // (X s< 13 | X u> 15) -> no change
1586       break;
1587     case ICmpInst::ICMP_NE:         // (X s< 13 | X != 15) -> X != 15
1588     case ICmpInst::ICMP_SLT:        // (X s< 13 | X s< 15) -> X s< 15
1589       return RHS;
1590     case ICmpInst::ICMP_ULT:        // (X s< 13 | X u< 15) -> no change
1591       break;
1592     }
1593     break;
1594   case ICmpInst::ICMP_UGT:
1595     switch (RHSCC) {
1596     default: llvm_unreachable("Unknown integer condition code!");
1597     case ICmpInst::ICMP_EQ:         // (X u> 13 | X == 15) -> X u> 13
1598     case ICmpInst::ICMP_UGT:        // (X u> 13 | X u> 15) -> X u> 13
1599       return LHS;
1600     case ICmpInst::ICMP_SGT:        // (X u> 13 | X s> 15) -> no change
1601       break;
1602     case ICmpInst::ICMP_NE:         // (X u> 13 | X != 15) -> true
1603     case ICmpInst::ICMP_ULT:        // (X u> 13 | X u< 15) -> true
1604       return ConstantInt::getTrue(LHS->getContext());
1605     case ICmpInst::ICMP_SLT:        // (X u> 13 | X s< 15) -> no change
1606       break;
1607     }
1608     break;
1609   case ICmpInst::ICMP_SGT:
1610     switch (RHSCC) {
1611     default: llvm_unreachable("Unknown integer condition code!");
1612     case ICmpInst::ICMP_EQ:         // (X s> 13 | X == 15) -> X > 13
1613     case ICmpInst::ICMP_SGT:        // (X s> 13 | X s> 15) -> X > 13
1614       return LHS;
1615     case ICmpInst::ICMP_UGT:        // (X s> 13 | X u> 15) -> no change
1616       break;
1617     case ICmpInst::ICMP_NE:         // (X s> 13 | X != 15) -> true
1618     case ICmpInst::ICMP_SLT:        // (X s> 13 | X s< 15) -> true
1619       return ConstantInt::getTrue(LHS->getContext());
1620     case ICmpInst::ICMP_ULT:        // (X s> 13 | X u< 15) -> no change
1621       break;
1622     }
1623     break;
1624   }
1625   return 0;
1626 }
1627
1628 /// FoldOrOfFCmps - Optimize (fcmp)|(fcmp).  NOTE: Unlike the rest of
1629 /// instcombine, this returns a Value which should already be inserted into the
1630 /// function.
1631 Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
1632   if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
1633       RHS->getPredicate() == FCmpInst::FCMP_UNO &&
1634       LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
1635     if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
1636       if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
1637         // If either of the constants are nans, then the whole thing returns
1638         // true.
1639         if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
1640           return ConstantInt::getTrue(LHS->getContext());
1641
1642         // Otherwise, no need to compare the two constants, compare the
1643         // rest.
1644         return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
1645       }
1646
1647     // Handle vector zeros.  This occurs because the canonical form of
1648     // "fcmp uno x,x" is "fcmp uno x, 0".
1649     if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
1650         isa<ConstantAggregateZero>(RHS->getOperand(1)))
1651       return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
1652
1653     return 0;
1654   }
1655
1656   Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
1657   Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
1658   FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
1659
1660   if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
1661     // Swap RHS operands to match LHS.
1662     Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
1663     std::swap(Op1LHS, Op1RHS);
1664   }
1665   if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
1666     // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
1667     if (Op0CC == Op1CC)
1668       return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
1669     if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
1670       return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
1671     if (Op0CC == FCmpInst::FCMP_FALSE)
1672       return RHS;
1673     if (Op1CC == FCmpInst::FCMP_FALSE)
1674       return LHS;
1675     bool Op0Ordered;
1676     bool Op1Ordered;
1677     unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
1678     unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
1679     if (Op0Ordered == Op1Ordered) {
1680       // If both are ordered or unordered, return a new fcmp with
1681       // or'ed predicates.
1682       return getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS, Builder);
1683     }
1684   }
1685   return 0;
1686 }
1687
1688 /// FoldOrWithConstants - This helper function folds:
1689 ///
1690 ///     ((A | B) & C1) | (B & C2)
1691 ///
1692 /// into:
1693 ///
1694 ///     (A & C1) | B
1695 ///
1696 /// when the XOR of the two constants is "all ones" (-1).
1697 Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
1698                                                Value *A, Value *B, Value *C) {
1699   ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
1700   if (!CI1) return 0;
1701
1702   Value *V1 = 0;
1703   ConstantInt *CI2 = 0;
1704   if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
1705
1706   APInt Xor = CI1->getValue() ^ CI2->getValue();
1707   if (!Xor.isAllOnesValue()) return 0;
1708
1709   if (V1 == A || V1 == B) {
1710     Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
1711     return BinaryOperator::CreateOr(NewOp, V1);
1712   }
1713
1714   return 0;
1715 }
1716
1717 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1718   bool Changed = SimplifyAssociativeOrCommutative(I);
1719   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1720
1721   if (Value *V = SimplifyOrInst(Op0, Op1, TD))
1722     return ReplaceInstUsesWith(I, V);
1723
1724   // (A&B)|(A&C) -> A&(B|C) etc
1725   if (Value *V = SimplifyUsingDistributiveLaws(I))
1726     return ReplaceInstUsesWith(I, V);
1727
1728   // See if we can simplify any instructions used by the instruction whose sole
1729   // purpose is to compute bits we don't care about.
1730   if (SimplifyDemandedInstructionBits(I))
1731     return &I;
1732
1733   if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1734     ConstantInt *C1 = 0; Value *X = 0;
1735     // (X & C1) | C2 --> (X | C2) & (C1|C2)
1736     // iff (C1 & C2) == 0.
1737     if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
1738         (RHS->getValue() & C1->getValue()) != 0 &&
1739         Op0->hasOneUse()) {
1740       Value *Or = Builder->CreateOr(X, RHS);
1741       Or->takeName(Op0);
1742       return BinaryOperator::CreateAnd(Or,
1743                          ConstantInt::get(I.getContext(),
1744                                           RHS->getValue() | C1->getValue()));
1745     }
1746
1747     // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1748     if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
1749         Op0->hasOneUse()) {
1750       Value *Or = Builder->CreateOr(X, RHS);
1751       Or->takeName(Op0);
1752       return BinaryOperator::CreateXor(Or,
1753                  ConstantInt::get(I.getContext(),
1754                                   C1->getValue() & ~RHS->getValue()));
1755     }
1756
1757     // Try to fold constant and into select arguments.
1758     if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1759       if (Instruction *R = FoldOpIntoSelect(I, SI))
1760         return R;
1761
1762     if (isa<PHINode>(Op0))
1763       if (Instruction *NV = FoldOpIntoPhi(I))
1764         return NV;
1765   }
1766
1767   Value *A = 0, *B = 0;
1768   ConstantInt *C1 = 0, *C2 = 0;
1769
1770   // (A | B) | C  and  A | (B | C)                  -> bswap if possible.
1771   // (A >> B) | (C << D)  and  (A << B) | (B >> C)  -> bswap if possible.
1772   if (match(Op0, m_Or(m_Value(), m_Value())) ||
1773       match(Op1, m_Or(m_Value(), m_Value())) ||
1774       (match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
1775        match(Op1, m_LogicalShift(m_Value(), m_Value())))) {
1776     if (Instruction *BSwap = MatchBSwap(I))
1777       return BSwap;
1778   }
1779
1780   // (X^C)|Y -> (X|Y)^C iff Y&C == 0
1781   if (Op0->hasOneUse() &&
1782       match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1783       MaskedValueIsZero(Op1, C1->getValue())) {
1784     Value *NOr = Builder->CreateOr(A, Op1);
1785     NOr->takeName(Op0);
1786     return BinaryOperator::CreateXor(NOr, C1);
1787   }
1788
1789   // Y|(X^C) -> (X|Y)^C iff Y&C == 0
1790   if (Op1->hasOneUse() &&
1791       match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1792       MaskedValueIsZero(Op0, C1->getValue())) {
1793     Value *NOr = Builder->CreateOr(A, Op0);
1794     NOr->takeName(Op0);
1795     return BinaryOperator::CreateXor(NOr, C1);
1796   }
1797
1798   // (A & C)|(B & D)
1799   Value *C = 0, *D = 0;
1800   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1801       match(Op1, m_And(m_Value(B), m_Value(D)))) {
1802     Value *V1 = 0, *V2 = 0;
1803     C1 = dyn_cast<ConstantInt>(C);
1804     C2 = dyn_cast<ConstantInt>(D);
1805     if (C1 && C2) {  // (A & C1)|(B & C2)
1806       // If we have: ((V + N) & C1) | (V & C2)
1807       // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1808       // replace with V+N.
1809       if (C1->getValue() == ~C2->getValue()) {
1810         if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
1811             match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1812           // Add commutes, try both ways.
1813           if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
1814             return ReplaceInstUsesWith(I, A);
1815           if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
1816             return ReplaceInstUsesWith(I, A);
1817         }
1818         // Or commutes, try both ways.
1819         if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
1820             match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1821           // Add commutes, try both ways.
1822           if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
1823             return ReplaceInstUsesWith(I, B);
1824           if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
1825             return ReplaceInstUsesWith(I, B);
1826         }
1827       }
1828
1829       if ((C1->getValue() & C2->getValue()) == 0) {
1830         // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
1831         // iff (C1&C2) == 0 and (N&~C1) == 0
1832         if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
1833             ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) ||  // (V|N)
1834              (V2 == B && MaskedValueIsZero(V1, ~C1->getValue()))))   // (N|V)
1835           return BinaryOperator::CreateAnd(A,
1836                                ConstantInt::get(A->getContext(),
1837                                                 C1->getValue()|C2->getValue()));
1838         // Or commutes, try both ways.
1839         if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
1840             ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) ||  // (V|N)
1841              (V2 == A && MaskedValueIsZero(V1, ~C2->getValue()))))   // (N|V)
1842           return BinaryOperator::CreateAnd(B,
1843                                ConstantInt::get(B->getContext(),
1844                                                 C1->getValue()|C2->getValue()));
1845
1846         // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2)
1847         // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0.
1848         ConstantInt *C3 = 0, *C4 = 0;
1849         if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) &&
1850             (C3->getValue() & ~C1->getValue()) == 0 &&
1851             match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) &&
1852             (C4->getValue() & ~C2->getValue()) == 0) {
1853           V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield");
1854           return BinaryOperator::CreateAnd(V2,
1855                                ConstantInt::get(B->getContext(),
1856                                                 C1->getValue()|C2->getValue()));
1857         }
1858       }
1859     }
1860
1861     // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) ->  C0 ? A : B, and commuted variants.
1862     // Don't do this for vector select idioms, the code generator doesn't handle
1863     // them well yet.
1864     if (!I.getType()->isVectorTy()) {
1865       if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
1866         return Match;
1867       if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
1868         return Match;
1869       if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
1870         return Match;
1871       if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
1872         return Match;
1873     }
1874
1875     // ((A&~B)|(~A&B)) -> A^B
1876     if ((match(C, m_Not(m_Specific(D))) &&
1877          match(B, m_Not(m_Specific(A)))))
1878       return BinaryOperator::CreateXor(A, D);
1879     // ((~B&A)|(~A&B)) -> A^B
1880     if ((match(A, m_Not(m_Specific(D))) &&
1881          match(B, m_Not(m_Specific(C)))))
1882       return BinaryOperator::CreateXor(C, D);
1883     // ((A&~B)|(B&~A)) -> A^B
1884     if ((match(C, m_Not(m_Specific(B))) &&
1885          match(D, m_Not(m_Specific(A)))))
1886       return BinaryOperator::CreateXor(A, B);
1887     // ((~B&A)|(B&~A)) -> A^B
1888     if ((match(A, m_Not(m_Specific(B))) &&
1889          match(D, m_Not(m_Specific(C)))))
1890       return BinaryOperator::CreateXor(C, B);
1891
1892     // ((A|B)&1)|(B&-2) -> (A&1) | B
1893     if (match(A, m_Or(m_Value(V1), m_Specific(B))) ||
1894         match(A, m_Or(m_Specific(B), m_Value(V1)))) {
1895       Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C);
1896       if (Ret) return Ret;
1897     }
1898     // (B&-2)|((A|B)&1) -> (A&1) | B
1899     if (match(B, m_Or(m_Specific(A), m_Value(V1))) ||
1900         match(B, m_Or(m_Value(V1), m_Specific(A)))) {
1901       Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D);
1902       if (Ret) return Ret;
1903     }
1904   }
1905
1906   // (X >> Z) | (Y >> Z)  -> (X|Y) >> Z  for all shifts.
1907   if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
1908     if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
1909       if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
1910           SI0->getOperand(1) == SI1->getOperand(1) &&
1911           (SI0->hasOneUse() || SI1->hasOneUse())) {
1912         Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
1913                                          SI0->getName());
1914         return BinaryOperator::Create(SI1->getOpcode(), NewOp,
1915                                       SI1->getOperand(1));
1916       }
1917   }
1918
1919   // (~A | ~B) == (~(A & B)) - De Morgan's Law
1920   if (Value *Op0NotVal = dyn_castNotVal(Op0))
1921     if (Value *Op1NotVal = dyn_castNotVal(Op1))
1922       if (Op0->hasOneUse() && Op1->hasOneUse()) {
1923         Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
1924                                         I.getName()+".demorgan");
1925         return BinaryOperator::CreateNot(And);
1926       }
1927
1928   // Canonicalize xor to the RHS.
1929   if (match(Op0, m_Xor(m_Value(), m_Value())))
1930     std::swap(Op0, Op1);
1931
1932   // A | ( A ^ B) -> A |  B
1933   // A | (~A ^ B) -> A | ~B
1934   if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
1935     if (Op0 == A || Op0 == B)
1936       return BinaryOperator::CreateOr(A, B);
1937
1938     if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) {
1939       Value *Not = Builder->CreateNot(B, B->getName()+".not");
1940       return BinaryOperator::CreateOr(Not, Op0);
1941     }
1942     if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) {
1943       Value *Not = Builder->CreateNot(A, A->getName()+".not");
1944       return BinaryOperator::CreateOr(Not, Op0);
1945     }
1946   }
1947
1948   // A | ~(A | B) -> A | ~B
1949   // A | ~(A ^ B) -> A | ~B
1950   if (match(Op1, m_Not(m_Value(A))))
1951     if (BinaryOperator *B = dyn_cast<BinaryOperator>(A))
1952       if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) &&
1953           Op1->hasOneUse() && (B->getOpcode() == Instruction::Or ||
1954                                B->getOpcode() == Instruction::Xor)) {
1955         Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) :
1956                                                  B->getOperand(0);
1957         Value *Not = Builder->CreateNot(NotOp, NotOp->getName()+".not");
1958         return BinaryOperator::CreateOr(Not, Op0);
1959       }
1960
1961   if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
1962     if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
1963       if (Value *Res = FoldOrOfICmps(LHS, RHS))
1964         return ReplaceInstUsesWith(I, Res);
1965
1966   // (fcmp uno x, c) | (fcmp uno y, c)  -> (fcmp uno x, y)
1967   if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
1968     if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
1969       if (Value *Res = FoldOrOfFCmps(LHS, RHS))
1970         return ReplaceInstUsesWith(I, Res);
1971
1972   // fold (or (cast A), (cast B)) -> (cast (or A, B))
1973   if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
1974     CastInst *Op1C = dyn_cast<CastInst>(Op1);
1975     if (Op1C && Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
1976       const Type *SrcTy = Op0C->getOperand(0)->getType();
1977       if (SrcTy == Op1C->getOperand(0)->getType() &&
1978           SrcTy->isIntOrIntVectorTy()) {
1979         Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0);
1980
1981         if ((!isa<ICmpInst>(Op0COp) || !isa<ICmpInst>(Op1COp)) &&
1982             // Only do this if the casts both really cause code to be
1983             // generated.
1984             ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
1985             ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
1986           Value *NewOp = Builder->CreateOr(Op0COp, Op1COp, I.getName());
1987           return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
1988         }
1989
1990         // If this is or(cast(icmp), cast(icmp)), try to fold this even if the
1991         // cast is otherwise not optimizable.  This happens for vector sexts.
1992         if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
1993           if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
1994             if (Value *Res = FoldOrOfICmps(LHS, RHS))
1995               return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
1996
1997         // If this is or(cast(fcmp), cast(fcmp)), try to fold this even if the
1998         // cast is otherwise not optimizable.  This happens for vector sexts.
1999         if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
2000           if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
2001             if (Value *Res = FoldOrOfFCmps(LHS, RHS))
2002               return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
2003       }
2004     }
2005   }
2006
2007   // Note: If we've gotten to the point of visiting the outer OR, then the
2008   // inner one couldn't be simplified.  If it was a constant, then it won't
2009   // be simplified by a later pass either, so we try swapping the inner/outer
2010   // ORs in the hopes that we'll be able to simplify it this way.
2011   // (X|C) | V --> (X|V) | C
2012   if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) &&
2013       match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) {
2014     Value *Inner = Builder->CreateOr(A, Op1);
2015     Inner->takeName(Op0);
2016     return BinaryOperator::CreateOr(Inner, C1);
2017   }
2018
2019   return Changed ? &I : 0;
2020 }
2021
2022 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2023   bool Changed = SimplifyAssociativeOrCommutative(I);
2024   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2025
2026   if (Value *V = SimplifyXorInst(Op0, Op1, TD))
2027     return ReplaceInstUsesWith(I, V);
2028
2029   // (A&B)^(A&C) -> A&(B^C) etc
2030   if (Value *V = SimplifyUsingDistributiveLaws(I))
2031     return ReplaceInstUsesWith(I, V);
2032
2033   // See if we can simplify any instructions used by the instruction whose sole
2034   // purpose is to compute bits we don't care about.
2035   if (SimplifyDemandedInstructionBits(I))
2036     return &I;
2037
2038   // Is this a ~ operation?
2039   if (Value *NotOp = dyn_castNotVal(&I)) {
2040     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
2041       if (Op0I->getOpcode() == Instruction::And ||
2042           Op0I->getOpcode() == Instruction::Or) {
2043         // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
2044         // ~(~X | Y) === (X & ~Y) - De Morgan's Law
2045         if (dyn_castNotVal(Op0I->getOperand(1)))
2046           Op0I->swapOperands();
2047         if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2048           Value *NotY =
2049             Builder->CreateNot(Op0I->getOperand(1),
2050                                Op0I->getOperand(1)->getName()+".not");
2051           if (Op0I->getOpcode() == Instruction::And)
2052             return BinaryOperator::CreateOr(Op0NotVal, NotY);
2053           return BinaryOperator::CreateAnd(Op0NotVal, NotY);
2054         }
2055
2056         // ~(X & Y) --> (~X | ~Y) - De Morgan's Law
2057         // ~(X | Y) === (~X & ~Y) - De Morgan's Law
2058         if (isFreeToInvert(Op0I->getOperand(0)) &&
2059             isFreeToInvert(Op0I->getOperand(1))) {
2060           Value *NotX =
2061             Builder->CreateNot(Op0I->getOperand(0), "notlhs");
2062           Value *NotY =
2063             Builder->CreateNot(Op0I->getOperand(1), "notrhs");
2064           if (Op0I->getOpcode() == Instruction::And)
2065             return BinaryOperator::CreateOr(NotX, NotY);
2066           return BinaryOperator::CreateAnd(NotX, NotY);
2067         }
2068
2069       } else if (Op0I->getOpcode() == Instruction::AShr) {
2070         // ~(~X >>s Y) --> (X >>s Y)
2071         if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0)))
2072           return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1));
2073       }
2074     }
2075   }
2076
2077
2078   if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2079     if (RHS->isOne() && Op0->hasOneUse())
2080       // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
2081       if (CmpInst *CI = dyn_cast<CmpInst>(Op0))
2082         return CmpInst::Create(CI->getOpcode(),
2083                                CI->getInversePredicate(),
2084                                CI->getOperand(0), CI->getOperand(1));
2085
2086     // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
2087     if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
2088       if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
2089         if (CI->hasOneUse() && Op0C->hasOneUse()) {
2090           Instruction::CastOps Opcode = Op0C->getOpcode();
2091           if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
2092               (RHS == ConstantExpr::getCast(Opcode,
2093                                            ConstantInt::getTrue(I.getContext()),
2094                                             Op0C->getDestTy()))) {
2095             CI->setPredicate(CI->getInversePredicate());
2096             return CastInst::Create(Opcode, CI, Op0C->getType());
2097           }
2098         }
2099       }
2100     }
2101
2102     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2103       // ~(c-X) == X-c-1 == X+(-c-1)
2104       if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2105         if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2106           Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2107           Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2108                                       ConstantInt::get(I.getType(), 1));
2109           return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
2110         }
2111
2112       if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
2113         if (Op0I->getOpcode() == Instruction::Add) {
2114           // ~(X-c) --> (-c-1)-X
2115           if (RHS->isAllOnesValue()) {
2116             Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2117             return BinaryOperator::CreateSub(
2118                            ConstantExpr::getSub(NegOp0CI,
2119                                       ConstantInt::get(I.getType(), 1)),
2120                                       Op0I->getOperand(0));
2121           } else if (RHS->getValue().isSignBit()) {
2122             // (X + C) ^ signbit -> (X + C + signbit)
2123             Constant *C = ConstantInt::get(I.getContext(),
2124                                            RHS->getValue() + Op0CI->getValue());
2125             return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
2126
2127           }
2128         } else if (Op0I->getOpcode() == Instruction::Or) {
2129           // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
2130           if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
2131             Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
2132             // Anything in both C1 and C2 is known to be zero, remove it from
2133             // NewRHS.
2134             Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
2135             NewRHS = ConstantExpr::getAnd(NewRHS,
2136                                        ConstantExpr::getNot(CommonBits));
2137             Worklist.Add(Op0I);
2138             I.setOperand(0, Op0I->getOperand(0));
2139             I.setOperand(1, NewRHS);
2140             return &I;
2141           }
2142         }
2143       }
2144     }
2145
2146     // Try to fold constant and into select arguments.
2147     if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2148       if (Instruction *R = FoldOpIntoSelect(I, SI))
2149         return R;
2150     if (isa<PHINode>(Op0))
2151       if (Instruction *NV = FoldOpIntoPhi(I))
2152         return NV;
2153   }
2154
2155   BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
2156   if (Op1I) {
2157     Value *A, *B;
2158     if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
2159       if (A == Op0) {              // B^(B|A) == (A|B)^B
2160         Op1I->swapOperands();
2161         I.swapOperands();
2162         std::swap(Op0, Op1);
2163       } else if (B == Op0) {       // B^(A|B) == (A|B)^B
2164         I.swapOperands();     // Simplified below.
2165         std::swap(Op0, Op1);
2166       }
2167     } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
2168                Op1I->hasOneUse()){
2169       if (A == Op0) {                                      // A^(A&B) -> A^(B&A)
2170         Op1I->swapOperands();
2171         std::swap(A, B);
2172       }
2173       if (B == Op0) {                                      // A^(B&A) -> (B&A)^A
2174         I.swapOperands();     // Simplified below.
2175         std::swap(Op0, Op1);
2176       }
2177     }
2178   }
2179
2180   BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
2181   if (Op0I) {
2182     Value *A, *B;
2183     if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
2184         Op0I->hasOneUse()) {
2185       if (A == Op1)                                  // (B|A)^B == (A|B)^B
2186         std::swap(A, B);
2187       if (B == Op1)                                  // (A|B)^B == A & ~B
2188         return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1, "tmp"));
2189     } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
2190                Op0I->hasOneUse()){
2191       if (A == Op1)                                        // (A&B)^A -> (B&A)^A
2192         std::swap(A, B);
2193       if (B == Op1 &&                                      // (B&A)^A == ~B & A
2194           !isa<ConstantInt>(Op1)) {  // Canonical form is (B&C)^C
2195         return BinaryOperator::CreateAnd(Builder->CreateNot(A, "tmp"), Op1);
2196       }
2197     }
2198   }
2199
2200   // (X >> Z) ^ (Y >> Z)  -> (X^Y) >> Z  for all shifts.
2201   if (Op0I && Op1I && Op0I->isShift() &&
2202       Op0I->getOpcode() == Op1I->getOpcode() &&
2203       Op0I->getOperand(1) == Op1I->getOperand(1) &&
2204       (Op1I->hasOneUse() || Op1I->hasOneUse())) {
2205     Value *NewOp =
2206       Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
2207                          Op0I->getName());
2208     return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
2209                                   Op1I->getOperand(1));
2210   }
2211
2212   if (Op0I && Op1I) {
2213     Value *A, *B, *C, *D;
2214     // (A & B)^(A | B) -> A ^ B
2215     if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
2216         match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
2217       if ((A == C && B == D) || (A == D && B == C))
2218         return BinaryOperator::CreateXor(A, B);
2219     }
2220     // (A | B)^(A & B) -> A ^ B
2221     if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
2222         match(Op1I, m_And(m_Value(C), m_Value(D)))) {
2223       if ((A == C && B == D) || (A == D && B == C))
2224         return BinaryOperator::CreateXor(A, B);
2225     }
2226   }
2227
2228   // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
2229   if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
2230     if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
2231       if (PredicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) {
2232         if (LHS->getOperand(0) == RHS->getOperand(1) &&
2233             LHS->getOperand(1) == RHS->getOperand(0))
2234           LHS->swapOperands();
2235         if (LHS->getOperand(0) == RHS->getOperand(0) &&
2236             LHS->getOperand(1) == RHS->getOperand(1)) {
2237           Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
2238           unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
2239           bool isSigned = LHS->isSigned() || RHS->isSigned();
2240           return ReplaceInstUsesWith(I,
2241                                getICmpValue(isSigned, Code, Op0, Op1, Builder));
2242         }
2243       }
2244
2245   // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
2246   if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
2247     if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
2248       if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
2249         const Type *SrcTy = Op0C->getOperand(0)->getType();
2250         if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegerTy() &&
2251             // Only do this if the casts both really cause code to be generated.
2252             ShouldOptimizeCast(Op0C->getOpcode(), Op0C->getOperand(0),
2253                                I.getType()) &&
2254             ShouldOptimizeCast(Op1C->getOpcode(), Op1C->getOperand(0),
2255                                I.getType())) {
2256           Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
2257                                             Op1C->getOperand(0), I.getName());
2258           return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
2259         }
2260       }
2261   }
2262
2263   return Changed ? &I : 0;
2264 }