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/Analysis/InstructionSimplify.h" 16 #include "llvm/IR/Intrinsics.h" 17 #include "llvm/Support/ConstantRange.h" 18 #include "llvm/Support/PatternMatch.h" 19 #include "llvm/Transforms/Utils/CmpInstAnalysis.h" 20 using namespace llvm; 21 using namespace PatternMatch; 22 23 24 /// AddOne - Add one to a ConstantInt. 25 static Constant *AddOne(ConstantInt *C) { 26 return ConstantInt::get(C->getContext(), C->getValue() + 1); 27 } 28 /// SubOne - Subtract one from a ConstantInt. 29 static Constant *SubOne(ConstantInt *C) { 30 return ConstantInt::get(C->getContext(), C->getValue()-1); 31 } 32 33 /// isFreeToInvert - Return true if the specified value is free to invert (apply 34 /// ~ to). This happens in cases where the ~ can be eliminated. 35 static inline bool isFreeToInvert(Value *V) { 36 // ~(~(X)) -> X. 37 if (BinaryOperator::isNot(V)) 38 return true; 39 40 // Constants can be considered to be not'ed values. 41 if (isa<ConstantInt>(V)) 42 return true; 43 44 // Compares can be inverted if they have a single use. 45 if (CmpInst *CI = dyn_cast<CmpInst>(V)) 46 return CI->hasOneUse(); 47 48 return false; 49 } 50 51 static inline Value *dyn_castNotVal(Value *V) { 52 // If this is not(not(x)) don't return that this is a not: we want the two 53 // not's to be folded first. 54 if (BinaryOperator::isNot(V)) { 55 Value *Operand = BinaryOperator::getNotArgument(V); 56 if (!isFreeToInvert(Operand)) 57 return Operand; 58 } 59 60 // Constants can be considered to be not'ed values... 61 if (ConstantInt *C = dyn_cast<ConstantInt>(V)) 62 return ConstantInt::get(C->getType(), ~C->getValue()); 63 return 0; 64 } 65 66 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp 67 /// predicate into a three bit mask. It also returns whether it is an ordered 68 /// predicate by reference. 69 static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) { 70 isOrdered = false; 71 switch (CC) { 72 case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000 73 case FCmpInst::FCMP_UNO: return 0; // 000 74 case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001 75 case FCmpInst::FCMP_UGT: return 1; // 001 76 case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010 77 case FCmpInst::FCMP_UEQ: return 2; // 010 78 case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011 79 case FCmpInst::FCMP_UGE: return 3; // 011 80 case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100 81 case FCmpInst::FCMP_ULT: return 4; // 100 82 case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101 83 case FCmpInst::FCMP_UNE: return 5; // 101 84 case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110 85 case FCmpInst::FCMP_ULE: return 6; // 110 86 // True -> 7 87 default: 88 // Not expecting FCMP_FALSE and FCMP_TRUE; 89 llvm_unreachable("Unexpected FCmp predicate!"); 90 } 91 } 92 93 /// getNewICmpValue - This is the complement of getICmpCode, which turns an 94 /// opcode and two operands into either a constant true or false, or a brand 95 /// new ICmp instruction. The sign is passed in to determine which kind 96 /// of predicate to use in the new icmp instruction. 97 static Value *getNewICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, 98 InstCombiner::BuilderTy *Builder) { 99 ICmpInst::Predicate NewPred; 100 if (Value *NewConstant = getICmpValue(Sign, Code, LHS, RHS, NewPred)) 101 return NewConstant; 102 return Builder->CreateICmp(NewPred, LHS, RHS); 103 } 104 105 /// getFCmpValue - This is the complement of getFCmpCode, which turns an 106 /// opcode and two operands into either a FCmp instruction. isordered is passed 107 /// in to determine which kind of predicate to use in the new fcmp instruction. 108 static Value *getFCmpValue(bool isordered, unsigned code, 109 Value *LHS, Value *RHS, 110 InstCombiner::BuilderTy *Builder) { 111 CmpInst::Predicate Pred; 112 switch (code) { 113 default: llvm_unreachable("Illegal FCmp code!"); 114 case 0: Pred = isordered ? FCmpInst::FCMP_ORD : FCmpInst::FCMP_UNO; break; 115 case 1: Pred = isordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; break; 116 case 2: Pred = isordered ? FCmpInst::FCMP_OEQ : FCmpInst::FCMP_UEQ; break; 117 case 3: Pred = isordered ? FCmpInst::FCMP_OGE : FCmpInst::FCMP_UGE; break; 118 case 4: Pred = isordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; break; 119 case 5: Pred = isordered ? FCmpInst::FCMP_ONE : FCmpInst::FCMP_UNE; break; 120 case 6: Pred = isordered ? FCmpInst::FCMP_OLE : FCmpInst::FCMP_ULE; break; 121 case 7: 122 if (!isordered) return ConstantInt::getTrue(LHS->getContext()); 123 Pred = FCmpInst::FCMP_ORD; break; 124 } 125 return Builder->CreateFCmp(Pred, LHS, RHS); 126 } 127 128 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where 129 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is 130 // guaranteed to be a binary operator. 131 Instruction *InstCombiner::OptAndOp(Instruction *Op, 132 ConstantInt *OpRHS, 133 ConstantInt *AndRHS, 134 BinaryOperator &TheAnd) { 135 Value *X = Op->getOperand(0); 136 Constant *Together = 0; 137 if (!Op->isShift()) 138 Together = ConstantExpr::getAnd(AndRHS, OpRHS); 139 140 switch (Op->getOpcode()) { 141 case Instruction::Xor: 142 if (Op->hasOneUse()) { 143 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) 144 Value *And = Builder->CreateAnd(X, AndRHS); 145 And->takeName(Op); 146 return BinaryOperator::CreateXor(And, Together); 147 } 148 break; 149 case Instruction::Or: 150 if (Op->hasOneUse()){ 151 if (Together != OpRHS) { 152 // (X | C1) & C2 --> (X | (C1&C2)) & C2 153 Value *Or = Builder->CreateOr(X, Together); 154 Or->takeName(Op); 155 return BinaryOperator::CreateAnd(Or, AndRHS); 156 } 157 158 ConstantInt *TogetherCI = dyn_cast<ConstantInt>(Together); 159 if (TogetherCI && !TogetherCI->isZero()){ 160 // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1 161 // NOTE: This reduces the number of bits set in the & mask, which 162 // can expose opportunities for store narrowing. 163 Together = ConstantExpr::getXor(AndRHS, Together); 164 Value *And = Builder->CreateAnd(X, Together); 165 And->takeName(Op); 166 return BinaryOperator::CreateOr(And, OpRHS); 167 } 168 } 169 170 break; 171 case Instruction::Add: 172 if (Op->hasOneUse()) { 173 // Adding a one to a single bit bit-field should be turned into an XOR 174 // of the bit. First thing to check is to see if this AND is with a 175 // single bit constant. 176 const APInt &AndRHSV = cast<ConstantInt>(AndRHS)->getValue(); 177 178 // If there is only one bit set. 179 if (AndRHSV.isPowerOf2()) { 180 // Ok, at this point, we know that we are masking the result of the 181 // ADD down to exactly one bit. If the constant we are adding has 182 // no bits set below this bit, then we can eliminate the ADD. 183 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue(); 184 185 // Check to see if any bits below the one bit set in AndRHSV are set. 186 if ((AddRHS & (AndRHSV-1)) == 0) { 187 // If not, the only thing that can effect the output of the AND is 188 // the bit specified by AndRHSV. If that bit is set, the effect of 189 // the XOR is to toggle the bit. If it is clear, then the ADD has 190 // no effect. 191 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop 192 TheAnd.setOperand(0, X); 193 return &TheAnd; 194 } else { 195 // Pull the XOR out of the AND. 196 Value *NewAnd = Builder->CreateAnd(X, AndRHS); 197 NewAnd->takeName(Op); 198 return BinaryOperator::CreateXor(NewAnd, AndRHS); 199 } 200 } 201 } 202 } 203 break; 204 205 case Instruction::Shl: { 206 // We know that the AND will not produce any of the bits shifted in, so if 207 // the anded constant includes them, clear them now! 208 // 209 uint32_t BitWidth = AndRHS->getType()->getBitWidth(); 210 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); 211 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal)); 212 ConstantInt *CI = ConstantInt::get(AndRHS->getContext(), 213 AndRHS->getValue() & ShlMask); 214 215 if (CI->getValue() == ShlMask) 216 // Masking out bits that the shift already masks. 217 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and. 218 219 if (CI != AndRHS) { // Reducing bits set in and. 220 TheAnd.setOperand(1, CI); 221 return &TheAnd; 222 } 223 break; 224 } 225 case Instruction::LShr: { 226 // We know that the AND will not produce any of the bits shifted in, so if 227 // the anded constant includes them, clear them now! This only applies to 228 // unsigned shifts, because a signed shr may bring in set bits! 229 // 230 uint32_t BitWidth = AndRHS->getType()->getBitWidth(); 231 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); 232 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); 233 ConstantInt *CI = ConstantInt::get(Op->getContext(), 234 AndRHS->getValue() & ShrMask); 235 236 if (CI->getValue() == ShrMask) 237 // Masking out bits that the shift already masks. 238 return ReplaceInstUsesWith(TheAnd, Op); 239 240 if (CI != AndRHS) { 241 TheAnd.setOperand(1, CI); // Reduce bits set in and cst. 242 return &TheAnd; 243 } 244 break; 245 } 246 case Instruction::AShr: 247 // Signed shr. 248 // See if this is shifting in some sign extension, then masking it out 249 // with an and. 250 if (Op->hasOneUse()) { 251 uint32_t BitWidth = AndRHS->getType()->getBitWidth(); 252 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); 253 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); 254 Constant *C = ConstantInt::get(Op->getContext(), 255 AndRHS->getValue() & ShrMask); 256 if (C == AndRHS) { // Masking out bits shifted in. 257 // (Val ashr C1) & C2 -> (Val lshr C1) & C2 258 // Make the argument unsigned. 259 Value *ShVal = Op->getOperand(0); 260 ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName()); 261 return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName()); 262 } 263 } 264 break; 265 } 266 return 0; 267 } 268 269 270 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is 271 /// true, otherwise (V < Lo || V >= Hi). In practice, we emit the more efficient 272 /// (V-Lo) \<u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates 273 /// whether to treat the V, Lo and HI as signed or not. IB is the location to 274 /// insert new instructions. 275 Value *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, 276 bool isSigned, bool Inside) { 277 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ? 278 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() && 279 "Lo is not <= Hi in range emission code!"); 280 281 if (Inside) { 282 if (Lo == Hi) // Trivially false. 283 return ConstantInt::getFalse(V->getContext()); 284 285 // V >= Min && V < Hi --> V < Hi 286 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) { 287 ICmpInst::Predicate pred = (isSigned ? 288 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT); 289 return Builder->CreateICmp(pred, V, Hi); 290 } 291 292 // Emit V-Lo <u Hi-Lo 293 Constant *NegLo = ConstantExpr::getNeg(Lo); 294 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off"); 295 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi); 296 return Builder->CreateICmpULT(Add, UpperBound); 297 } 298 299 if (Lo == Hi) // Trivially true. 300 return ConstantInt::getTrue(V->getContext()); 301 302 // V < Min || V >= Hi -> V > Hi-1 303 Hi = SubOne(cast<ConstantInt>(Hi)); 304 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) { 305 ICmpInst::Predicate pred = (isSigned ? 306 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT); 307 return Builder->CreateICmp(pred, V, Hi); 308 } 309 310 // Emit V-Lo >u Hi-1-Lo 311 // Note that Hi has already had one subtracted from it, above. 312 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo)); 313 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off"); 314 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi); 315 return Builder->CreateICmpUGT(Add, LowerBound); 316 } 317 318 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with 319 // any number of 0s on either side. The 1s are allowed to wrap from LSB to 320 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is 321 // not, since all 1s are not contiguous. 322 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) { 323 const APInt& V = Val->getValue(); 324 uint32_t BitWidth = Val->getType()->getBitWidth(); 325 if (!APIntOps::isShiftedMask(BitWidth, V)) return false; 326 327 // look for the first zero bit after the run of ones 328 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros(); 329 // look for the first non-zero bit 330 ME = V.getActiveBits(); 331 return true; 332 } 333 334 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask, 335 /// where isSub determines whether the operator is a sub. If we can fold one of 336 /// the following xforms: 337 /// 338 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask 339 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 340 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 341 /// 342 /// return (A +/- B). 343 /// 344 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS, 345 ConstantInt *Mask, bool isSub, 346 Instruction &I) { 347 Instruction *LHSI = dyn_cast<Instruction>(LHS); 348 if (!LHSI || LHSI->getNumOperands() != 2 || 349 !isa<ConstantInt>(LHSI->getOperand(1))) return 0; 350 351 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1)); 352 353 switch (LHSI->getOpcode()) { 354 default: return 0; 355 case Instruction::And: 356 if (ConstantExpr::getAnd(N, Mask) == Mask) { 357 // If the AndRHS is a power of two minus one (0+1+), this is simple. 358 if ((Mask->getValue().countLeadingZeros() + 359 Mask->getValue().countPopulation()) == 360 Mask->getValue().getBitWidth()) 361 break; 362 363 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+ 364 // part, we don't need any explicit masks to take them out of A. If that 365 // is all N is, ignore it. 366 uint32_t MB = 0, ME = 0; 367 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive 368 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth(); 369 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1)); 370 if (MaskedValueIsZero(RHS, Mask)) 371 break; 372 } 373 } 374 return 0; 375 case Instruction::Or: 376 case Instruction::Xor: 377 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0 378 if ((Mask->getValue().countLeadingZeros() + 379 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth() 380 && ConstantExpr::getAnd(N, Mask)->isNullValue()) 381 break; 382 return 0; 383 } 384 385 if (isSub) 386 return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold"); 387 return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold"); 388 } 389 390 /// enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C) 391 /// One of A and B is considered the mask, the other the value. This is 392 /// described as the "AMask" or "BMask" part of the enum. If the enum 393 /// contains only "Mask", then both A and B can be considered masks. 394 /// If A is the mask, then it was proven, that (A & C) == C. This 395 /// is trivial if C == A, or C == 0. If both A and C are constants, this 396 /// proof is also easy. 397 /// For the following explanations we assume that A is the mask. 398 /// The part "AllOnes" declares, that the comparison is true only 399 /// if (A & B) == A, or all bits of A are set in B. 400 /// Example: (icmp eq (A & 3), 3) -> FoldMskICmp_AMask_AllOnes 401 /// The part "AllZeroes" declares, that the comparison is true only 402 /// if (A & B) == 0, or all bits of A are cleared in B. 403 /// Example: (icmp eq (A & 3), 0) -> FoldMskICmp_Mask_AllZeroes 404 /// The part "Mixed" declares, that (A & B) == C and C might or might not 405 /// contain any number of one bits and zero bits. 406 /// Example: (icmp eq (A & 3), 1) -> FoldMskICmp_AMask_Mixed 407 /// The Part "Not" means, that in above descriptions "==" should be replaced 408 /// by "!=". 409 /// Example: (icmp ne (A & 3), 3) -> FoldMskICmp_AMask_NotAllOnes 410 /// If the mask A contains a single bit, then the following is equivalent: 411 /// (icmp eq (A & B), A) equals (icmp ne (A & B), 0) 412 /// (icmp ne (A & B), A) equals (icmp eq (A & B), 0) 413 enum MaskedICmpType { 414 FoldMskICmp_AMask_AllOnes = 1, 415 FoldMskICmp_AMask_NotAllOnes = 2, 416 FoldMskICmp_BMask_AllOnes = 4, 417 FoldMskICmp_BMask_NotAllOnes = 8, 418 FoldMskICmp_Mask_AllZeroes = 16, 419 FoldMskICmp_Mask_NotAllZeroes = 32, 420 FoldMskICmp_AMask_Mixed = 64, 421 FoldMskICmp_AMask_NotMixed = 128, 422 FoldMskICmp_BMask_Mixed = 256, 423 FoldMskICmp_BMask_NotMixed = 512 424 }; 425 426 /// return the set of pattern classes (from MaskedICmpType) 427 /// that (icmp SCC (A & B), C) satisfies 428 static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C, 429 ICmpInst::Predicate SCC) 430 { 431 ConstantInt *ACst = dyn_cast<ConstantInt>(A); 432 ConstantInt *BCst = dyn_cast<ConstantInt>(B); 433 ConstantInt *CCst = dyn_cast<ConstantInt>(C); 434 bool icmp_eq = (SCC == ICmpInst::ICMP_EQ); 435 bool icmp_abit = (ACst != 0 && !ACst->isZero() && 436 ACst->getValue().isPowerOf2()); 437 bool icmp_bbit = (BCst != 0 && !BCst->isZero() && 438 BCst->getValue().isPowerOf2()); 439 unsigned result = 0; 440 if (CCst != 0 && CCst->isZero()) { 441 // if C is zero, then both A and B qualify as mask 442 result |= (icmp_eq ? (FoldMskICmp_Mask_AllZeroes | 443 FoldMskICmp_Mask_AllZeroes | 444 FoldMskICmp_AMask_Mixed | 445 FoldMskICmp_BMask_Mixed) 446 : (FoldMskICmp_Mask_NotAllZeroes | 447 FoldMskICmp_Mask_NotAllZeroes | 448 FoldMskICmp_AMask_NotMixed | 449 FoldMskICmp_BMask_NotMixed)); 450 if (icmp_abit) 451 result |= (icmp_eq ? (FoldMskICmp_AMask_NotAllOnes | 452 FoldMskICmp_AMask_NotMixed) 453 : (FoldMskICmp_AMask_AllOnes | 454 FoldMskICmp_AMask_Mixed)); 455 if (icmp_bbit) 456 result |= (icmp_eq ? (FoldMskICmp_BMask_NotAllOnes | 457 FoldMskICmp_BMask_NotMixed) 458 : (FoldMskICmp_BMask_AllOnes | 459 FoldMskICmp_BMask_Mixed)); 460 return result; 461 } 462 if (A == C) { 463 result |= (icmp_eq ? (FoldMskICmp_AMask_AllOnes | 464 FoldMskICmp_AMask_Mixed) 465 : (FoldMskICmp_AMask_NotAllOnes | 466 FoldMskICmp_AMask_NotMixed)); 467 if (icmp_abit) 468 result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes | 469 FoldMskICmp_AMask_NotMixed) 470 : (FoldMskICmp_Mask_AllZeroes | 471 FoldMskICmp_AMask_Mixed)); 472 } else if (ACst != 0 && CCst != 0 && 473 ConstantExpr::getAnd(ACst, CCst) == CCst) { 474 result |= (icmp_eq ? FoldMskICmp_AMask_Mixed 475 : FoldMskICmp_AMask_NotMixed); 476 } 477 if (B == C) { 478 result |= (icmp_eq ? (FoldMskICmp_BMask_AllOnes | 479 FoldMskICmp_BMask_Mixed) 480 : (FoldMskICmp_BMask_NotAllOnes | 481 FoldMskICmp_BMask_NotMixed)); 482 if (icmp_bbit) 483 result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes | 484 FoldMskICmp_BMask_NotMixed) 485 : (FoldMskICmp_Mask_AllZeroes | 486 FoldMskICmp_BMask_Mixed)); 487 } else if (BCst != 0 && CCst != 0 && 488 ConstantExpr::getAnd(BCst, CCst) == CCst) { 489 result |= (icmp_eq ? FoldMskICmp_BMask_Mixed 490 : FoldMskICmp_BMask_NotMixed); 491 } 492 return result; 493 } 494 495 /// decomposeBitTestICmp - Decompose an icmp into the form ((X & Y) pred Z) 496 /// if possible. The returned predicate is either == or !=. Returns false if 497 /// decomposition fails. 498 static bool decomposeBitTestICmp(const ICmpInst *I, ICmpInst::Predicate &Pred, 499 Value *&X, Value *&Y, Value *&Z) { 500 // X < 0 is equivalent to (X & SignBit) != 0. 501 if (I->getPredicate() == ICmpInst::ICMP_SLT) 502 if (ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1))) 503 if (C->isZero()) { 504 X = I->getOperand(0); 505 Y = ConstantInt::get(I->getContext(), 506 APInt::getSignBit(C->getBitWidth())); 507 Pred = ICmpInst::ICMP_NE; 508 Z = C; 509 return true; 510 } 511 512 // X > -1 is equivalent to (X & SignBit) == 0. 513 if (I->getPredicate() == ICmpInst::ICMP_SGT) 514 if (ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1))) 515 if (C->isAllOnesValue()) { 516 X = I->getOperand(0); 517 Y = ConstantInt::get(I->getContext(), 518 APInt::getSignBit(C->getBitWidth())); 519 Pred = ICmpInst::ICMP_EQ; 520 Z = ConstantInt::getNullValue(C->getType()); 521 return true; 522 } 523 524 return false; 525 } 526 527 /// foldLogOpOfMaskedICmpsHelper: 528 /// handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) 529 /// return the set of pattern classes (from MaskedICmpType) 530 /// that both LHS and RHS satisfy 531 static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A, 532 Value*& B, Value*& C, 533 Value*& D, Value*& E, 534 ICmpInst *LHS, ICmpInst *RHS, 535 ICmpInst::Predicate &LHSCC, 536 ICmpInst::Predicate &RHSCC) { 537 if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0; 538 // vectors are not (yet?) supported 539 if (LHS->getOperand(0)->getType()->isVectorTy()) return 0; 540 541 // Here comes the tricky part: 542 // LHS might be of the form L11 & L12 == X, X == L21 & L22, 543 // and L11 & L12 == L21 & L22. The same goes for RHS. 544 // Now we must find those components L** and R**, that are equal, so 545 // that we can extract the parameters A, B, C, D, and E for the canonical 546 // above. 547 Value *L1 = LHS->getOperand(0); 548 Value *L2 = LHS->getOperand(1); 549 Value *L11,*L12,*L21,*L22; 550 // Check whether the icmp can be decomposed into a bit test. 551 if (decomposeBitTestICmp(LHS, LHSCC, L11, L12, L2)) { 552 L21 = L22 = L1 = 0; 553 } else { 554 // Look for ANDs in the LHS icmp. 555 if (match(L1, m_And(m_Value(L11), m_Value(L12)))) { 556 if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) 557 L21 = L22 = 0; 558 } else { 559 if (!match(L2, m_And(m_Value(L11), m_Value(L12)))) 560 return 0; 561 std::swap(L1, L2); 562 L21 = L22 = 0; 563 } 564 } 565 566 // Bail if LHS was a icmp that can't be decomposed into an equality. 567 if (!ICmpInst::isEquality(LHSCC)) 568 return 0; 569 570 Value *R1 = RHS->getOperand(0); 571 Value *R2 = RHS->getOperand(1); 572 Value *R11,*R12; 573 bool ok = false; 574 if (decomposeBitTestICmp(RHS, RHSCC, R11, R12, R2)) { 575 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { 576 A = R11; D = R12; 577 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { 578 A = R12; D = R11; 579 } else { 580 return 0; 581 } 582 E = R2; R1 = 0; ok = true; 583 } else if (match(R1, m_And(m_Value(R11), m_Value(R12)))) { 584 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { 585 A = R11; D = R12; E = R2; ok = true; 586 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { 587 A = R12; D = R11; E = R2; ok = true; 588 } 589 } 590 591 // Bail if RHS was a icmp that can't be decomposed into an equality. 592 if (!ICmpInst::isEquality(RHSCC)) 593 return 0; 594 595 // Look for ANDs in on the right side of the RHS icmp. 596 if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) { 597 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { 598 A = R11; D = R12; E = R1; ok = true; 599 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { 600 A = R12; D = R11; E = R1; ok = true; 601 } else { 602 return 0; 603 } 604 } 605 if (!ok) 606 return 0; 607 608 if (L11 == A) { 609 B = L12; C = L2; 610 } else if (L12 == A) { 611 B = L11; C = L2; 612 } else if (L21 == A) { 613 B = L22; C = L1; 614 } else if (L22 == A) { 615 B = L21; C = L1; 616 } 617 618 unsigned left_type = getTypeOfMaskedICmp(A, B, C, LHSCC); 619 unsigned right_type = getTypeOfMaskedICmp(A, D, E, RHSCC); 620 return left_type & right_type; 621 } 622 /// foldLogOpOfMaskedICmps: 623 /// try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) 624 /// into a single (icmp(A & X) ==/!= Y) 625 static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, 626 ICmpInst::Predicate NEWCC, 627 llvm::InstCombiner::BuilderTy* Builder) { 628 Value *A = 0, *B = 0, *C = 0, *D = 0, *E = 0; 629 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); 630 unsigned mask = foldLogOpOfMaskedICmpsHelper(A, B, C, D, E, LHS, RHS, 631 LHSCC, RHSCC); 632 if (mask == 0) return 0; 633 assert(ICmpInst::isEquality(LHSCC) && ICmpInst::isEquality(RHSCC) && 634 "foldLogOpOfMaskedICmpsHelper must return an equality predicate."); 635 636 if (NEWCC == ICmpInst::ICMP_NE) 637 mask >>= 1; // treat "Not"-states as normal states 638 639 if (mask & FoldMskICmp_Mask_AllZeroes) { 640 // (icmp eq (A & B), 0) & (icmp eq (A & D), 0) 641 // -> (icmp eq (A & (B|D)), 0) 642 Value* newOr = Builder->CreateOr(B, D); 643 Value* newAnd = Builder->CreateAnd(A, newOr); 644 // we can't use C as zero, because we might actually handle 645 // (icmp ne (A & B), B) & (icmp ne (A & D), D) 646 // with B and D, having a single bit set 647 Value* zero = Constant::getNullValue(A->getType()); 648 return Builder->CreateICmp(NEWCC, newAnd, zero); 649 } 650 if (mask & FoldMskICmp_BMask_AllOnes) { 651 // (icmp eq (A & B), B) & (icmp eq (A & D), D) 652 // -> (icmp eq (A & (B|D)), (B|D)) 653 Value* newOr = Builder->CreateOr(B, D); 654 Value* newAnd = Builder->CreateAnd(A, newOr); 655 return Builder->CreateICmp(NEWCC, newAnd, newOr); 656 } 657 if (mask & FoldMskICmp_AMask_AllOnes) { 658 // (icmp eq (A & B), A) & (icmp eq (A & D), A) 659 // -> (icmp eq (A & (B&D)), A) 660 Value* newAnd1 = Builder->CreateAnd(B, D); 661 Value* newAnd = Builder->CreateAnd(A, newAnd1); 662 return Builder->CreateICmp(NEWCC, newAnd, A); 663 } 664 if (mask & FoldMskICmp_BMask_Mixed) { 665 // (icmp eq (A & B), C) & (icmp eq (A & D), E) 666 // We already know that B & C == C && D & E == E. 667 // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of 668 // C and E, which are shared by both the mask B and the mask D, don't 669 // contradict, then we can transform to 670 // -> (icmp eq (A & (B|D)), (C|E)) 671 // Currently, we only handle the case of B, C, D, and E being constant. 672 ConstantInt *BCst = dyn_cast<ConstantInt>(B); 673 if (BCst == 0) return 0; 674 ConstantInt *DCst = dyn_cast<ConstantInt>(D); 675 if (DCst == 0) return 0; 676 // we can't simply use C and E, because we might actually handle 677 // (icmp ne (A & B), B) & (icmp eq (A & D), D) 678 // with B and D, having a single bit set 679 680 ConstantInt *CCst = dyn_cast<ConstantInt>(C); 681 if (CCst == 0) return 0; 682 if (LHSCC != NEWCC) 683 CCst = dyn_cast<ConstantInt>( ConstantExpr::getXor(BCst, CCst) ); 684 ConstantInt *ECst = dyn_cast<ConstantInt>(E); 685 if (ECst == 0) return 0; 686 if (RHSCC != NEWCC) 687 ECst = dyn_cast<ConstantInt>( ConstantExpr::getXor(DCst, ECst) ); 688 ConstantInt* MCst = dyn_cast<ConstantInt>( 689 ConstantExpr::getAnd(ConstantExpr::getAnd(BCst, DCst), 690 ConstantExpr::getXor(CCst, ECst)) ); 691 // if there is a conflict we should actually return a false for the 692 // whole construct 693 if (!MCst->isZero()) 694 return 0; 695 Value *newOr1 = Builder->CreateOr(B, D); 696 Value *newOr2 = ConstantExpr::getOr(CCst, ECst); 697 Value *newAnd = Builder->CreateAnd(A, newOr1); 698 return Builder->CreateICmp(NEWCC, newAnd, newOr2); 699 } 700 return 0; 701 } 702 703 /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible. 704 Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) { 705 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); 706 707 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B) 708 if (PredicatesFoldable(LHSCC, RHSCC)) { 709 if (LHS->getOperand(0) == RHS->getOperand(1) && 710 LHS->getOperand(1) == RHS->getOperand(0)) 711 LHS->swapOperands(); 712 if (LHS->getOperand(0) == RHS->getOperand(0) && 713 LHS->getOperand(1) == RHS->getOperand(1)) { 714 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); 715 unsigned Code = getICmpCode(LHS) & getICmpCode(RHS); 716 bool isSigned = LHS->isSigned() || RHS->isSigned(); 717 return getNewICmpValue(isSigned, Code, Op0, Op1, Builder); 718 } 719 } 720 721 // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E) 722 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_EQ, Builder)) 723 return V; 724 725 // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). 726 Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0); 727 ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1)); 728 ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1)); 729 if (LHSCst == 0 || RHSCst == 0) return 0; 730 731 if (LHSCst == RHSCst && LHSCC == RHSCC) { 732 // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C) 733 // where C is a power of 2 734 if (LHSCC == ICmpInst::ICMP_ULT && 735 LHSCst->getValue().isPowerOf2()) { 736 Value *NewOr = Builder->CreateOr(Val, Val2); 737 return Builder->CreateICmp(LHSCC, NewOr, LHSCst); 738 } 739 740 // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0) 741 if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) { 742 Value *NewOr = Builder->CreateOr(Val, Val2); 743 return Builder->CreateICmp(LHSCC, NewOr, LHSCst); 744 } 745 } 746 747 // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2 748 // where CMAX is the all ones value for the truncated type, 749 // iff the lower bits of C2 and CA are zero. 750 if (LHSCC == ICmpInst::ICMP_EQ && LHSCC == RHSCC && 751 LHS->hasOneUse() && RHS->hasOneUse()) { 752 Value *V; 753 ConstantInt *AndCst, *SmallCst = 0, *BigCst = 0; 754 755 // (trunc x) == C1 & (and x, CA) == C2 756 // (and x, CA) == C2 & (trunc x) == C1 757 if (match(Val2, m_Trunc(m_Value(V))) && 758 match(Val, m_And(m_Specific(V), m_ConstantInt(AndCst)))) { 759 SmallCst = RHSCst; 760 BigCst = LHSCst; 761 } else if (match(Val, m_Trunc(m_Value(V))) && 762 match(Val2, m_And(m_Specific(V), m_ConstantInt(AndCst)))) { 763 SmallCst = LHSCst; 764 BigCst = RHSCst; 765 } 766 767 if (SmallCst && BigCst) { 768 unsigned BigBitSize = BigCst->getType()->getBitWidth(); 769 unsigned SmallBitSize = SmallCst->getType()->getBitWidth(); 770 771 // Check that the low bits are zero. 772 APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); 773 if ((Low & AndCst->getValue()) == 0 && (Low & BigCst->getValue()) == 0) { 774 Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue()); 775 APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue(); 776 Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N); 777 return Builder->CreateICmp(LHSCC, NewAnd, NewVal); 778 } 779 } 780 } 781 782 // From here on, we only handle: 783 // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler. 784 if (Val != Val2) return 0; 785 786 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. 787 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || 788 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || 789 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || 790 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) 791 return 0; 792 793 // Make a constant range that's the intersection of the two icmp ranges. 794 // If the intersection is empty, we know that the result is false. 795 ConstantRange LHSRange = 796 ConstantRange::makeICmpRegion(LHSCC, LHSCst->getValue()); 797 ConstantRange RHSRange = 798 ConstantRange::makeICmpRegion(RHSCC, RHSCst->getValue()); 799 800 if (LHSRange.intersectWith(RHSRange).isEmptySet()) 801 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); 802 803 // We can't fold (ugt x, C) & (sgt x, C2). 804 if (!PredicatesFoldable(LHSCC, RHSCC)) 805 return 0; 806 807 // Ensure that the larger constant is on the RHS. 808 bool ShouldSwap; 809 if (CmpInst::isSigned(LHSCC) || 810 (ICmpInst::isEquality(LHSCC) && 811 CmpInst::isSigned(RHSCC))) 812 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); 813 else 814 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); 815 816 if (ShouldSwap) { 817 std::swap(LHS, RHS); 818 std::swap(LHSCst, RHSCst); 819 std::swap(LHSCC, RHSCC); 820 } 821 822 // At this point, we know we have two icmp instructions 823 // comparing a value against two constants and and'ing the result 824 // together. Because of the above check, we know that we only have 825 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know 826 // (from the icmp folding check above), that the two constants 827 // are not equal and that the larger constant is on the RHS 828 assert(LHSCst != RHSCst && "Compares not folded above?"); 829 830 switch (LHSCC) { 831 default: llvm_unreachable("Unknown integer condition code!"); 832 case ICmpInst::ICMP_EQ: 833 switch (RHSCC) { 834 default: llvm_unreachable("Unknown integer condition code!"); 835 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13 836 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13 837 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13 838 return LHS; 839 } 840 case ICmpInst::ICMP_NE: 841 switch (RHSCC) { 842 default: llvm_unreachable("Unknown integer condition code!"); 843 case ICmpInst::ICMP_ULT: 844 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13 845 return Builder->CreateICmpULT(Val, LHSCst); 846 break; // (X != 13 & X u< 15) -> no change 847 case ICmpInst::ICMP_SLT: 848 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13 849 return Builder->CreateICmpSLT(Val, LHSCst); 850 break; // (X != 13 & X s< 15) -> no change 851 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15 852 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15 853 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15 854 return RHS; 855 case ICmpInst::ICMP_NE: 856 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1 857 Constant *AddCST = ConstantExpr::getNeg(LHSCst); 858 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off"); 859 return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1)); 860 } 861 break; // (X != 13 & X != 15) -> no change 862 } 863 break; 864 case ICmpInst::ICMP_ULT: 865 switch (RHSCC) { 866 default: llvm_unreachable("Unknown integer condition code!"); 867 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false 868 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false 869 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); 870 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change 871 break; 872 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13 873 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13 874 return LHS; 875 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change 876 break; 877 } 878 break; 879 case ICmpInst::ICMP_SLT: 880 switch (RHSCC) { 881 default: llvm_unreachable("Unknown integer condition code!"); 882 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change 883 break; 884 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13 885 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13 886 return LHS; 887 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change 888 break; 889 } 890 break; 891 case ICmpInst::ICMP_UGT: 892 switch (RHSCC) { 893 default: llvm_unreachable("Unknown integer condition code!"); 894 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15 895 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15 896 return RHS; 897 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change 898 break; 899 case ICmpInst::ICMP_NE: 900 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14 901 return Builder->CreateICmp(LHSCC, Val, RHSCst); 902 break; // (X u> 13 & X != 15) -> no change 903 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1 904 return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true); 905 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change 906 break; 907 } 908 break; 909 case ICmpInst::ICMP_SGT: 910 switch (RHSCC) { 911 default: llvm_unreachable("Unknown integer condition code!"); 912 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15 913 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15 914 return RHS; 915 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change 916 break; 917 case ICmpInst::ICMP_NE: 918 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14 919 return Builder->CreateICmp(LHSCC, Val, RHSCst); 920 break; // (X s> 13 & X != 15) -> no change 921 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1 922 return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true); 923 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change 924 break; 925 } 926 break; 927 } 928 929 return 0; 930 } 931 932 /// FoldAndOfFCmps - Optimize (fcmp)&(fcmp). NOTE: Unlike the rest of 933 /// instcombine, this returns a Value which should already be inserted into the 934 /// function. 935 Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { 936 if (LHS->getPredicate() == FCmpInst::FCMP_ORD && 937 RHS->getPredicate() == FCmpInst::FCMP_ORD) { 938 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y) 939 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1))) 940 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) { 941 // If either of the constants are nans, then the whole thing returns 942 // false. 943 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) 944 return ConstantInt::getFalse(LHS->getContext()); 945 return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); 946 } 947 948 // Handle vector zeros. This occurs because the canonical form of 949 // "fcmp ord x,x" is "fcmp ord x, 0". 950 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) && 951 isa<ConstantAggregateZero>(RHS->getOperand(1))) 952 return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); 953 return 0; 954 } 955 956 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); 957 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); 958 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); 959 960 961 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { 962 // Swap RHS operands to match LHS. 963 Op1CC = FCmpInst::getSwappedPredicate(Op1CC); 964 std::swap(Op1LHS, Op1RHS); 965 } 966 967 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { 968 // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y). 969 if (Op0CC == Op1CC) 970 return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); 971 if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE) 972 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); 973 if (Op0CC == FCmpInst::FCMP_TRUE) 974 return RHS; 975 if (Op1CC == FCmpInst::FCMP_TRUE) 976 return LHS; 977 978 bool Op0Ordered; 979 bool Op1Ordered; 980 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); 981 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); 982 // uno && ord -> false 983 if (Op0Pred == 0 && Op1Pred == 0 && Op0Ordered != Op1Ordered) 984 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); 985 if (Op1Pred == 0) { 986 std::swap(LHS, RHS); 987 std::swap(Op0Pred, Op1Pred); 988 std::swap(Op0Ordered, Op1Ordered); 989 } 990 if (Op0Pred == 0) { 991 // uno && ueq -> uno && (uno || eq) -> uno 992 // ord && olt -> ord && (ord && lt) -> olt 993 if (!Op0Ordered && (Op0Ordered == Op1Ordered)) 994 return LHS; 995 if (Op0Ordered && (Op0Ordered == Op1Ordered)) 996 return RHS; 997 998 // uno && oeq -> uno && (ord && eq) -> false 999 if (!Op0Ordered) 1000 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); 1001 // ord && ueq -> ord && (uno || eq) -> oeq 1002 return getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS, Builder); 1003 } 1004 } 1005 1006 return 0; 1007 } 1008 1009 1010 Instruction *InstCombiner::visitAnd(BinaryOperator &I) { 1011 bool Changed = SimplifyAssociativeOrCommutative(I); 1012 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 1013 1014 if (Value *V = SimplifyAndInst(Op0, Op1, TD)) 1015 return ReplaceInstUsesWith(I, V); 1016 1017 // (A|B)&(A|C) -> A|(B&C) etc 1018 if (Value *V = SimplifyUsingDistributiveLaws(I)) 1019 return ReplaceInstUsesWith(I, V); 1020 1021 // See if we can simplify any instructions used by the instruction whose sole 1022 // purpose is to compute bits we don't care about. 1023 if (SimplifyDemandedInstructionBits(I)) 1024 return &I; 1025 1026 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) { 1027 const APInt &AndRHSMask = AndRHS->getValue(); 1028 1029 // Optimize a variety of ((val OP C1) & C2) combinations... 1030 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { 1031 Value *Op0LHS = Op0I->getOperand(0); 1032 Value *Op0RHS = Op0I->getOperand(1); 1033 switch (Op0I->getOpcode()) { 1034 default: break; 1035 case Instruction::Xor: 1036 case Instruction::Or: { 1037 // If the mask is only needed on one incoming arm, push it up. 1038 if (!Op0I->hasOneUse()) break; 1039 1040 APInt NotAndRHS(~AndRHSMask); 1041 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) { 1042 // Not masking anything out for the LHS, move to RHS. 1043 Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS, 1044 Op0RHS->getName()+".masked"); 1045 return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS); 1046 } 1047 if (!isa<Constant>(Op0RHS) && 1048 MaskedValueIsZero(Op0RHS, NotAndRHS)) { 1049 // Not masking anything out for the RHS, move to LHS. 1050 Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS, 1051 Op0LHS->getName()+".masked"); 1052 return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS); 1053 } 1054 1055 break; 1056 } 1057 case Instruction::Add: 1058 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS. 1059 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 1060 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 1061 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I)) 1062 return BinaryOperator::CreateAnd(V, AndRHS); 1063 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I)) 1064 return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes 1065 break; 1066 1067 case Instruction::Sub: 1068 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS. 1069 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 1070 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 1071 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I)) 1072 return BinaryOperator::CreateAnd(V, AndRHS); 1073 1074 // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS 1075 // has 1's for all bits that the subtraction with A might affect. 1076 if (Op0I->hasOneUse() && !match(Op0LHS, m_Zero())) { 1077 uint32_t BitWidth = AndRHSMask.getBitWidth(); 1078 uint32_t Zeros = AndRHSMask.countLeadingZeros(); 1079 APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros); 1080 1081 if (MaskedValueIsZero(Op0LHS, Mask)) { 1082 Value *NewNeg = Builder->CreateNeg(Op0RHS); 1083 return BinaryOperator::CreateAnd(NewNeg, AndRHS); 1084 } 1085 } 1086 break; 1087 1088 case Instruction::Shl: 1089 case Instruction::LShr: 1090 // (1 << x) & 1 --> zext(x == 0) 1091 // (1 >> x) & 1 --> zext(x == 0) 1092 if (AndRHSMask == 1 && Op0LHS == AndRHS) { 1093 Value *NewICmp = 1094 Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType())); 1095 return new ZExtInst(NewICmp, I.getType()); 1096 } 1097 break; 1098 } 1099 1100 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) 1101 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I)) 1102 return Res; 1103 } 1104 1105 // If this is an integer truncation, and if the source is an 'and' with 1106 // immediate, transform it. This frequently occurs for bitfield accesses. 1107 { 1108 Value *X = 0; ConstantInt *YC = 0; 1109 if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) { 1110 // Change: and (trunc (and X, YC) to T), C2 1111 // into : and (trunc X to T), trunc(YC) & C2 1112 // This will fold the two constants together, which may allow 1113 // other simplifications. 1114 Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk"); 1115 Constant *C3 = ConstantExpr::getTrunc(YC, I.getType()); 1116 C3 = ConstantExpr::getAnd(C3, AndRHS); 1117 return BinaryOperator::CreateAnd(NewCast, C3); 1118 } 1119 } 1120 1121 // Try to fold constant and into select arguments. 1122 if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) 1123 if (Instruction *R = FoldOpIntoSelect(I, SI)) 1124 return R; 1125 if (isa<PHINode>(Op0)) 1126 if (Instruction *NV = FoldOpIntoPhi(I)) 1127 return NV; 1128 } 1129 1130 1131 // (~A & ~B) == (~(A | B)) - De Morgan's Law 1132 if (Value *Op0NotVal = dyn_castNotVal(Op0)) 1133 if (Value *Op1NotVal = dyn_castNotVal(Op1)) 1134 if (Op0->hasOneUse() && Op1->hasOneUse()) { 1135 Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal, 1136 I.getName()+".demorgan"); 1137 return BinaryOperator::CreateNot(Or); 1138 } 1139 1140 { 1141 Value *A = 0, *B = 0, *C = 0, *D = 0; 1142 // (A|B) & ~(A&B) -> A^B 1143 if (match(Op0, m_Or(m_Value(A), m_Value(B))) && 1144 match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) && 1145 ((A == C && B == D) || (A == D && B == C))) 1146 return BinaryOperator::CreateXor(A, B); 1147 1148 // ~(A&B) & (A|B) -> A^B 1149 if (match(Op1, m_Or(m_Value(A), m_Value(B))) && 1150 match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) && 1151 ((A == C && B == D) || (A == D && B == C))) 1152 return BinaryOperator::CreateXor(A, B); 1153 1154 // A&(A^B) => A & ~B 1155 { 1156 Value *tmpOp0 = Op0; 1157 Value *tmpOp1 = Op1; 1158 if (Op0->hasOneUse() && 1159 match(Op0, m_Xor(m_Value(A), m_Value(B)))) { 1160 if (A == Op1 || B == Op1 ) { 1161 tmpOp1 = Op0; 1162 tmpOp0 = Op1; 1163 // Simplify below 1164 } 1165 } 1166 1167 if (tmpOp1->hasOneUse() && 1168 match(tmpOp1, m_Xor(m_Value(A), m_Value(B)))) { 1169 if (B == tmpOp0) { 1170 std::swap(A, B); 1171 } 1172 // Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if 1173 // A is originally -1 (or a vector of -1 and undefs), then we enter 1174 // an endless loop. By checking that A is non-constant we ensure that 1175 // we will never get to the loop. 1176 if (A == tmpOp0 && !isa<Constant>(A)) // A&(A^B) -> A & ~B 1177 return BinaryOperator::CreateAnd(A, Builder->CreateNot(B)); 1178 } 1179 } 1180 1181 // (A&((~A)|B)) -> A&B 1182 if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) || 1183 match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1))))) 1184 return BinaryOperator::CreateAnd(A, Op1); 1185 if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) || 1186 match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0))))) 1187 return BinaryOperator::CreateAnd(A, Op0); 1188 } 1189 1190 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) 1191 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0)) 1192 if (Value *Res = FoldAndOfICmps(LHS, RHS)) 1193 return ReplaceInstUsesWith(I, Res); 1194 1195 // If and'ing two fcmp, try combine them into one. 1196 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) 1197 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) 1198 if (Value *Res = FoldAndOfFCmps(LHS, RHS)) 1199 return ReplaceInstUsesWith(I, Res); 1200 1201 1202 // fold (and (cast A), (cast B)) -> (cast (and A, B)) 1203 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) 1204 if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) { 1205 Type *SrcTy = Op0C->getOperand(0)->getType(); 1206 if (Op0C->getOpcode() == Op1C->getOpcode() && // same cast kind ? 1207 SrcTy == Op1C->getOperand(0)->getType() && 1208 SrcTy->isIntOrIntVectorTy()) { 1209 Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0); 1210 1211 // Only do this if the casts both really cause code to be generated. 1212 if (ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) && 1213 ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) { 1214 Value *NewOp = Builder->CreateAnd(Op0COp, Op1COp, I.getName()); 1215 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); 1216 } 1217 1218 // If this is and(cast(icmp), cast(icmp)), try to fold this even if the 1219 // cast is otherwise not optimizable. This happens for vector sexts. 1220 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp)) 1221 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp)) 1222 if (Value *Res = FoldAndOfICmps(LHS, RHS)) 1223 return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); 1224 1225 // If this is and(cast(fcmp), cast(fcmp)), try to fold this even if the 1226 // cast is otherwise not optimizable. This happens for vector sexts. 1227 if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp)) 1228 if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp)) 1229 if (Value *Res = FoldAndOfFCmps(LHS, RHS)) 1230 return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); 1231 } 1232 } 1233 1234 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts. 1235 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) { 1236 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0)) 1237 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && 1238 SI0->getOperand(1) == SI1->getOperand(1) && 1239 (SI0->hasOneUse() || SI1->hasOneUse())) { 1240 Value *NewOp = 1241 Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0), 1242 SI0->getName()); 1243 return BinaryOperator::Create(SI1->getOpcode(), NewOp, 1244 SI1->getOperand(1)); 1245 } 1246 } 1247 1248 { 1249 Value *X = 0; 1250 bool OpsSwapped = false; 1251 // Canonicalize SExt or Not to the LHS 1252 if (match(Op1, m_SExt(m_Value())) || 1253 match(Op1, m_Not(m_Value()))) { 1254 std::swap(Op0, Op1); 1255 OpsSwapped = true; 1256 } 1257 1258 // Fold (and (sext bool to A), B) --> (select bool, B, 0) 1259 if (match(Op0, m_SExt(m_Value(X))) && 1260 X->getType()->getScalarType()->isIntegerTy(1)) { 1261 Value *Zero = Constant::getNullValue(Op1->getType()); 1262 return SelectInst::Create(X, Op1, Zero); 1263 } 1264 1265 // Fold (and ~(sext bool to A), B) --> (select bool, 0, B) 1266 if (match(Op0, m_Not(m_SExt(m_Value(X)))) && 1267 X->getType()->getScalarType()->isIntegerTy(1)) { 1268 Value *Zero = Constant::getNullValue(Op0->getType()); 1269 return SelectInst::Create(X, Zero, Op1); 1270 } 1271 1272 if (OpsSwapped) 1273 std::swap(Op0, Op1); 1274 } 1275 1276 return Changed ? &I : 0; 1277 } 1278 1279 /// CollectBSwapParts - Analyze the specified subexpression and see if it is 1280 /// capable of providing pieces of a bswap. The subexpression provides pieces 1281 /// of a bswap if it is proven that each of the non-zero bytes in the output of 1282 /// the expression came from the corresponding "byte swapped" byte in some other 1283 /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then 1284 /// we know that the expression deposits the low byte of %X into the high byte 1285 /// of the bswap result and that all other bytes are zero. This expression is 1286 /// accepted, the high byte of ByteValues is set to X to indicate a correct 1287 /// match. 1288 /// 1289 /// This function returns true if the match was unsuccessful and false if so. 1290 /// On entry to the function the "OverallLeftShift" is a signed integer value 1291 /// indicating the number of bytes that the subexpression is later shifted. For 1292 /// example, if the expression is later right shifted by 16 bits, the 1293 /// OverallLeftShift value would be -2 on entry. This is used to specify which 1294 /// byte of ByteValues is actually being set. 1295 /// 1296 /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding 1297 /// byte is masked to zero by a user. For example, in (X & 255), X will be 1298 /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits 1299 /// this function to working on up to 32-byte (256 bit) values. ByteMask is 1300 /// always in the local (OverallLeftShift) coordinate space. 1301 /// 1302 static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask, 1303 SmallVector<Value*, 8> &ByteValues) { 1304 if (Instruction *I = dyn_cast<Instruction>(V)) { 1305 // If this is an or instruction, it may be an inner node of the bswap. 1306 if (I->getOpcode() == Instruction::Or) { 1307 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, 1308 ByteValues) || 1309 CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask, 1310 ByteValues); 1311 } 1312 1313 // If this is a logical shift by a constant multiple of 8, recurse with 1314 // OverallLeftShift and ByteMask adjusted. 1315 if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) { 1316 unsigned ShAmt = 1317 cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U); 1318 // Ensure the shift amount is defined and of a byte value. 1319 if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size())) 1320 return true; 1321 1322 unsigned ByteShift = ShAmt >> 3; 1323 if (I->getOpcode() == Instruction::Shl) { 1324 // X << 2 -> collect(X, +2) 1325 OverallLeftShift += ByteShift; 1326 ByteMask >>= ByteShift; 1327 } else { 1328 // X >>u 2 -> collect(X, -2) 1329 OverallLeftShift -= ByteShift; 1330 ByteMask <<= ByteShift; 1331 ByteMask &= (~0U >> (32-ByteValues.size())); 1332 } 1333 1334 if (OverallLeftShift >= (int)ByteValues.size()) return true; 1335 if (OverallLeftShift <= -(int)ByteValues.size()) return true; 1336 1337 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, 1338 ByteValues); 1339 } 1340 1341 // If this is a logical 'and' with a mask that clears bytes, clear the 1342 // corresponding bytes in ByteMask. 1343 if (I->getOpcode() == Instruction::And && 1344 isa<ConstantInt>(I->getOperand(1))) { 1345 // Scan every byte of the and mask, seeing if the byte is either 0 or 255. 1346 unsigned NumBytes = ByteValues.size(); 1347 APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255); 1348 const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue(); 1349 1350 for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) { 1351 // If this byte is masked out by a later operation, we don't care what 1352 // the and mask is. 1353 if ((ByteMask & (1 << i)) == 0) 1354 continue; 1355 1356 // If the AndMask is all zeros for this byte, clear the bit. 1357 APInt MaskB = AndMask & Byte; 1358 if (MaskB == 0) { 1359 ByteMask &= ~(1U << i); 1360 continue; 1361 } 1362 1363 // If the AndMask is not all ones for this byte, it's not a bytezap. 1364 if (MaskB != Byte) 1365 return true; 1366 1367 // Otherwise, this byte is kept. 1368 } 1369 1370 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, 1371 ByteValues); 1372 } 1373 } 1374 1375 // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be 1376 // the input value to the bswap. Some observations: 1) if more than one byte 1377 // is demanded from this input, then it could not be successfully assembled 1378 // into a byteswap. At least one of the two bytes would not be aligned with 1379 // their ultimate destination. 1380 if (!isPowerOf2_32(ByteMask)) return true; 1381 unsigned InputByteNo = CountTrailingZeros_32(ByteMask); 1382 1383 // 2) The input and ultimate destinations must line up: if byte 3 of an i32 1384 // is demanded, it needs to go into byte 0 of the result. This means that the 1385 // byte needs to be shifted until it lands in the right byte bucket. The 1386 // shift amount depends on the position: if the byte is coming from the high 1387 // part of the value (e.g. byte 3) then it must be shifted right. If from the 1388 // low part, it must be shifted left. 1389 unsigned DestByteNo = InputByteNo + OverallLeftShift; 1390 if (ByteValues.size()-1-DestByteNo != InputByteNo) 1391 return true; 1392 1393 // If the destination byte value is already defined, the values are or'd 1394 // together, which isn't a bswap (unless it's an or of the same bits). 1395 if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V) 1396 return true; 1397 ByteValues[DestByteNo] = V; 1398 return false; 1399 } 1400 1401 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom. 1402 /// If so, insert the new bswap intrinsic and return it. 1403 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) { 1404 IntegerType *ITy = dyn_cast<IntegerType>(I.getType()); 1405 if (!ITy || ITy->getBitWidth() % 16 || 1406 // ByteMask only allows up to 32-byte values. 1407 ITy->getBitWidth() > 32*8) 1408 return 0; // Can only bswap pairs of bytes. Can't do vectors. 1409 1410 /// ByteValues - For each byte of the result, we keep track of which value 1411 /// defines each byte. 1412 SmallVector<Value*, 8> ByteValues; 1413 ByteValues.resize(ITy->getBitWidth()/8); 1414 1415 // Try to find all the pieces corresponding to the bswap. 1416 uint32_t ByteMask = ~0U >> (32-ByteValues.size()); 1417 if (CollectBSwapParts(&I, 0, ByteMask, ByteValues)) 1418 return 0; 1419 1420 // Check to see if all of the bytes come from the same value. 1421 Value *V = ByteValues[0]; 1422 if (V == 0) return 0; // Didn't find a byte? Must be zero. 1423 1424 // Check to make sure that all of the bytes come from the same value. 1425 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i) 1426 if (ByteValues[i] != V) 1427 return 0; 1428 Module *M = I.getParent()->getParent()->getParent(); 1429 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, ITy); 1430 return CallInst::Create(F, V); 1431 } 1432 1433 /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check 1434 /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then 1435 /// we can simplify this expression to "cond ? C : D or B". 1436 static Instruction *MatchSelectFromAndOr(Value *A, Value *B, 1437 Value *C, Value *D) { 1438 // If A is not a select of -1/0, this cannot match. 1439 Value *Cond = 0; 1440 if (!match(A, m_SExt(m_Value(Cond))) || 1441 !Cond->getType()->isIntegerTy(1)) 1442 return 0; 1443 1444 // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B. 1445 if (match(D, m_Not(m_SExt(m_Specific(Cond))))) 1446 return SelectInst::Create(Cond, C, B); 1447 if (match(D, m_SExt(m_Not(m_Specific(Cond))))) 1448 return SelectInst::Create(Cond, C, B); 1449 1450 // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D. 1451 if (match(B, m_Not(m_SExt(m_Specific(Cond))))) 1452 return SelectInst::Create(Cond, C, D); 1453 if (match(B, m_SExt(m_Not(m_Specific(Cond))))) 1454 return SelectInst::Create(Cond, C, D); 1455 return 0; 1456 } 1457 1458 /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible. 1459 Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) { 1460 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); 1461 1462 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) 1463 if (PredicatesFoldable(LHSCC, RHSCC)) { 1464 if (LHS->getOperand(0) == RHS->getOperand(1) && 1465 LHS->getOperand(1) == RHS->getOperand(0)) 1466 LHS->swapOperands(); 1467 if (LHS->getOperand(0) == RHS->getOperand(0) && 1468 LHS->getOperand(1) == RHS->getOperand(1)) { 1469 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); 1470 unsigned Code = getICmpCode(LHS) | getICmpCode(RHS); 1471 bool isSigned = LHS->isSigned() || RHS->isSigned(); 1472 return getNewICmpValue(isSigned, Code, Op0, Op1, Builder); 1473 } 1474 } 1475 1476 // handle (roughly): 1477 // (icmp ne (A & B), C) | (icmp ne (A & D), E) 1478 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_NE, Builder)) 1479 return V; 1480 1481 // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). 1482 Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0); 1483 ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1)); 1484 ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1)); 1485 if (LHSCst == 0 || RHSCst == 0) return 0; 1486 1487 if (LHSCst == RHSCst && LHSCC == RHSCC) { 1488 // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0) 1489 if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) { 1490 Value *NewOr = Builder->CreateOr(Val, Val2); 1491 return Builder->CreateICmp(LHSCC, NewOr, LHSCst); 1492 } 1493 } 1494 1495 // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1) 1496 // iff C2 + CA == C1. 1497 if (LHSCC == ICmpInst::ICMP_ULT && RHSCC == ICmpInst::ICMP_EQ) { 1498 ConstantInt *AddCst; 1499 if (match(Val, m_Add(m_Specific(Val2), m_ConstantInt(AddCst)))) 1500 if (RHSCst->getValue() + AddCst->getValue() == LHSCst->getValue()) 1501 return Builder->CreateICmpULE(Val, LHSCst); 1502 } 1503 1504 // From here on, we only handle: 1505 // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler. 1506 if (Val != Val2) return 0; 1507 1508 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. 1509 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || 1510 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || 1511 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || 1512 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) 1513 return 0; 1514 1515 // We can't fold (ugt x, C) | (sgt x, C2). 1516 if (!PredicatesFoldable(LHSCC, RHSCC)) 1517 return 0; 1518 1519 // Ensure that the larger constant is on the RHS. 1520 bool ShouldSwap; 1521 if (CmpInst::isSigned(LHSCC) || 1522 (ICmpInst::isEquality(LHSCC) && 1523 CmpInst::isSigned(RHSCC))) 1524 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); 1525 else 1526 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); 1527 1528 if (ShouldSwap) { 1529 std::swap(LHS, RHS); 1530 std::swap(LHSCst, RHSCst); 1531 std::swap(LHSCC, RHSCC); 1532 } 1533 1534 // At this point, we know we have two icmp instructions 1535 // comparing a value against two constants and or'ing the result 1536 // together. Because of the above check, we know that we only have 1537 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the 1538 // icmp folding check above), that the two constants are not 1539 // equal. 1540 assert(LHSCst != RHSCst && "Compares not folded above?"); 1541 1542 switch (LHSCC) { 1543 default: llvm_unreachable("Unknown integer condition code!"); 1544 case ICmpInst::ICMP_EQ: 1545 switch (RHSCC) { 1546 default: llvm_unreachable("Unknown integer condition code!"); 1547 case ICmpInst::ICMP_EQ: 1548 if (LHSCst == SubOne(RHSCst)) { 1549 // (X == 13 | X == 14) -> X-13 <u 2 1550 Constant *AddCST = ConstantExpr::getNeg(LHSCst); 1551 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off"); 1552 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst); 1553 return Builder->CreateICmpULT(Add, AddCST); 1554 } 1555 1556 if (LHS->getOperand(0) == RHS->getOperand(0)) { 1557 // if LHSCst and RHSCst differ only by one bit: 1558 // (A == C1 || A == C2) -> (A & ~(C1 ^ C2)) == C1 1559 assert(LHSCst->getValue().ule(LHSCst->getValue())); 1560 1561 APInt Xor = LHSCst->getValue() ^ RHSCst->getValue(); 1562 if (Xor.isPowerOf2()) { 1563 Value *NegCst = Builder->getInt(~Xor); 1564 Value *And = Builder->CreateAnd(LHS->getOperand(0), NegCst); 1565 return Builder->CreateICmp(ICmpInst::ICMP_EQ, And, LHSCst); 1566 } 1567 } 1568 1569 break; // (X == 13 | X == 15) -> no change 1570 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change 1571 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change 1572 break; 1573 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15 1574 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15 1575 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15 1576 return RHS; 1577 } 1578 break; 1579 case ICmpInst::ICMP_NE: 1580 switch (RHSCC) { 1581 default: llvm_unreachable("Unknown integer condition code!"); 1582 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13 1583 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13 1584 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13 1585 return LHS; 1586 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true 1587 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true 1588 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true 1589 return ConstantInt::getTrue(LHS->getContext()); 1590 } 1591 case ICmpInst::ICMP_ULT: 1592 switch (RHSCC) { 1593 default: llvm_unreachable("Unknown integer condition code!"); 1594 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change 1595 break; 1596 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2 1597 // If RHSCst is [us]MAXINT, it is always false. Not handling 1598 // this can cause overflow. 1599 if (RHSCst->isMaxValue(false)) 1600 return LHS; 1601 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false); 1602 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change 1603 break; 1604 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15 1605 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15 1606 return RHS; 1607 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change 1608 break; 1609 } 1610 break; 1611 case ICmpInst::ICMP_SLT: 1612 switch (RHSCC) { 1613 default: llvm_unreachable("Unknown integer condition code!"); 1614 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change 1615 break; 1616 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2 1617 // If RHSCst is [us]MAXINT, it is always false. Not handling 1618 // this can cause overflow. 1619 if (RHSCst->isMaxValue(true)) 1620 return LHS; 1621 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false); 1622 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change 1623 break; 1624 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15 1625 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15 1626 return RHS; 1627 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change 1628 break; 1629 } 1630 break; 1631 case ICmpInst::ICMP_UGT: 1632 switch (RHSCC) { 1633 default: llvm_unreachable("Unknown integer condition code!"); 1634 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13 1635 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13 1636 return LHS; 1637 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change 1638 break; 1639 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true 1640 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true 1641 return ConstantInt::getTrue(LHS->getContext()); 1642 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change 1643 break; 1644 } 1645 break; 1646 case ICmpInst::ICMP_SGT: 1647 switch (RHSCC) { 1648 default: llvm_unreachable("Unknown integer condition code!"); 1649 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13 1650 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13 1651 return LHS; 1652 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change 1653 break; 1654 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true 1655 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true 1656 return ConstantInt::getTrue(LHS->getContext()); 1657 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change 1658 break; 1659 } 1660 break; 1661 } 1662 return 0; 1663 } 1664 1665 /// FoldOrOfFCmps - Optimize (fcmp)|(fcmp). NOTE: Unlike the rest of 1666 /// instcombine, this returns a Value which should already be inserted into the 1667 /// function. 1668 Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { 1669 if (LHS->getPredicate() == FCmpInst::FCMP_UNO && 1670 RHS->getPredicate() == FCmpInst::FCMP_UNO && 1671 LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) { 1672 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1))) 1673 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) { 1674 // If either of the constants are nans, then the whole thing returns 1675 // true. 1676 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) 1677 return ConstantInt::getTrue(LHS->getContext()); 1678 1679 // Otherwise, no need to compare the two constants, compare the 1680 // rest. 1681 return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); 1682 } 1683 1684 // Handle vector zeros. This occurs because the canonical form of 1685 // "fcmp uno x,x" is "fcmp uno x, 0". 1686 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) && 1687 isa<ConstantAggregateZero>(RHS->getOperand(1))) 1688 return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); 1689 1690 return 0; 1691 } 1692 1693 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); 1694 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); 1695 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); 1696 1697 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { 1698 // Swap RHS operands to match LHS. 1699 Op1CC = FCmpInst::getSwappedPredicate(Op1CC); 1700 std::swap(Op1LHS, Op1RHS); 1701 } 1702 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { 1703 // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y). 1704 if (Op0CC == Op1CC) 1705 return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); 1706 if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE) 1707 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1); 1708 if (Op0CC == FCmpInst::FCMP_FALSE) 1709 return RHS; 1710 if (Op1CC == FCmpInst::FCMP_FALSE) 1711 return LHS; 1712 bool Op0Ordered; 1713 bool Op1Ordered; 1714 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); 1715 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); 1716 if (Op0Ordered == Op1Ordered) { 1717 // If both are ordered or unordered, return a new fcmp with 1718 // or'ed predicates. 1719 return getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS, Builder); 1720 } 1721 } 1722 return 0; 1723 } 1724 1725 /// FoldOrWithConstants - This helper function folds: 1726 /// 1727 /// ((A | B) & C1) | (B & C2) 1728 /// 1729 /// into: 1730 /// 1731 /// (A & C1) | B 1732 /// 1733 /// when the XOR of the two constants is "all ones" (-1). 1734 Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op, 1735 Value *A, Value *B, Value *C) { 1736 ConstantInt *CI1 = dyn_cast<ConstantInt>(C); 1737 if (!CI1) return 0; 1738 1739 Value *V1 = 0; 1740 ConstantInt *CI2 = 0; 1741 if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0; 1742 1743 APInt Xor = CI1->getValue() ^ CI2->getValue(); 1744 if (!Xor.isAllOnesValue()) return 0; 1745 1746 if (V1 == A || V1 == B) { 1747 Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1); 1748 return BinaryOperator::CreateOr(NewOp, V1); 1749 } 1750 1751 return 0; 1752 } 1753 1754 Instruction *InstCombiner::visitOr(BinaryOperator &I) { 1755 bool Changed = SimplifyAssociativeOrCommutative(I); 1756 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 1757 1758 if (Value *V = SimplifyOrInst(Op0, Op1, TD)) 1759 return ReplaceInstUsesWith(I, V); 1760 1761 // (A&B)|(A&C) -> A&(B|C) etc 1762 if (Value *V = SimplifyUsingDistributiveLaws(I)) 1763 return ReplaceInstUsesWith(I, V); 1764 1765 // See if we can simplify any instructions used by the instruction whose sole 1766 // purpose is to compute bits we don't care about. 1767 if (SimplifyDemandedInstructionBits(I)) 1768 return &I; 1769 1770 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { 1771 ConstantInt *C1 = 0; Value *X = 0; 1772 // (X & C1) | C2 --> (X | C2) & (C1|C2) 1773 // iff (C1 & C2) == 0. 1774 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && 1775 (RHS->getValue() & C1->getValue()) != 0 && 1776 Op0->hasOneUse()) { 1777 Value *Or = Builder->CreateOr(X, RHS); 1778 Or->takeName(Op0); 1779 return BinaryOperator::CreateAnd(Or, 1780 ConstantInt::get(I.getContext(), 1781 RHS->getValue() | C1->getValue())); 1782 } 1783 1784 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) 1785 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && 1786 Op0->hasOneUse()) { 1787 Value *Or = Builder->CreateOr(X, RHS); 1788 Or->takeName(Op0); 1789 return BinaryOperator::CreateXor(Or, 1790 ConstantInt::get(I.getContext(), 1791 C1->getValue() & ~RHS->getValue())); 1792 } 1793 1794 // Try to fold constant and into select arguments. 1795 if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) 1796 if (Instruction *R = FoldOpIntoSelect(I, SI)) 1797 return R; 1798 1799 if (isa<PHINode>(Op0)) 1800 if (Instruction *NV = FoldOpIntoPhi(I)) 1801 return NV; 1802 } 1803 1804 Value *A = 0, *B = 0; 1805 ConstantInt *C1 = 0, *C2 = 0; 1806 1807 // (A | B) | C and A | (B | C) -> bswap if possible. 1808 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible. 1809 if (match(Op0, m_Or(m_Value(), m_Value())) || 1810 match(Op1, m_Or(m_Value(), m_Value())) || 1811 (match(Op0, m_LogicalShift(m_Value(), m_Value())) && 1812 match(Op1, m_LogicalShift(m_Value(), m_Value())))) { 1813 if (Instruction *BSwap = MatchBSwap(I)) 1814 return BSwap; 1815 } 1816 1817 // (X^C)|Y -> (X|Y)^C iff Y&C == 0 1818 if (Op0->hasOneUse() && 1819 match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) && 1820 MaskedValueIsZero(Op1, C1->getValue())) { 1821 Value *NOr = Builder->CreateOr(A, Op1); 1822 NOr->takeName(Op0); 1823 return BinaryOperator::CreateXor(NOr, C1); 1824 } 1825 1826 // Y|(X^C) -> (X|Y)^C iff Y&C == 0 1827 if (Op1->hasOneUse() && 1828 match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) && 1829 MaskedValueIsZero(Op0, C1->getValue())) { 1830 Value *NOr = Builder->CreateOr(A, Op0); 1831 NOr->takeName(Op0); 1832 return BinaryOperator::CreateXor(NOr, C1); 1833 } 1834 1835 // (A & C)|(B & D) 1836 Value *C = 0, *D = 0; 1837 if (match(Op0, m_And(m_Value(A), m_Value(C))) && 1838 match(Op1, m_And(m_Value(B), m_Value(D)))) { 1839 Value *V1 = 0, *V2 = 0; 1840 C1 = dyn_cast<ConstantInt>(C); 1841 C2 = dyn_cast<ConstantInt>(D); 1842 if (C1 && C2) { // (A & C1)|(B & C2) 1843 // If we have: ((V + N) & C1) | (V & C2) 1844 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 1845 // replace with V+N. 1846 if (C1->getValue() == ~C2->getValue()) { 1847 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+ 1848 match(A, m_Add(m_Value(V1), m_Value(V2)))) { 1849 // Add commutes, try both ways. 1850 if (V1 == B && MaskedValueIsZero(V2, C2->getValue())) 1851 return ReplaceInstUsesWith(I, A); 1852 if (V2 == B && MaskedValueIsZero(V1, C2->getValue())) 1853 return ReplaceInstUsesWith(I, A); 1854 } 1855 // Or commutes, try both ways. 1856 if ((C1->getValue() & (C1->getValue()+1)) == 0 && 1857 match(B, m_Add(m_Value(V1), m_Value(V2)))) { 1858 // Add commutes, try both ways. 1859 if (V1 == A && MaskedValueIsZero(V2, C1->getValue())) 1860 return ReplaceInstUsesWith(I, B); 1861 if (V2 == A && MaskedValueIsZero(V1, C1->getValue())) 1862 return ReplaceInstUsesWith(I, B); 1863 } 1864 } 1865 1866 if ((C1->getValue() & C2->getValue()) == 0) { 1867 // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2) 1868 // iff (C1&C2) == 0 and (N&~C1) == 0 1869 if (match(A, m_Or(m_Value(V1), m_Value(V2))) && 1870 ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N) 1871 (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V) 1872 return BinaryOperator::CreateAnd(A, 1873 ConstantInt::get(A->getContext(), 1874 C1->getValue()|C2->getValue())); 1875 // Or commutes, try both ways. 1876 if (match(B, m_Or(m_Value(V1), m_Value(V2))) && 1877 ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N) 1878 (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V) 1879 return BinaryOperator::CreateAnd(B, 1880 ConstantInt::get(B->getContext(), 1881 C1->getValue()|C2->getValue())); 1882 1883 // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2) 1884 // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0. 1885 ConstantInt *C3 = 0, *C4 = 0; 1886 if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) && 1887 (C3->getValue() & ~C1->getValue()) == 0 && 1888 match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) && 1889 (C4->getValue() & ~C2->getValue()) == 0) { 1890 V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield"); 1891 return BinaryOperator::CreateAnd(V2, 1892 ConstantInt::get(B->getContext(), 1893 C1->getValue()|C2->getValue())); 1894 } 1895 } 1896 } 1897 1898 // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants. 1899 // Don't do this for vector select idioms, the code generator doesn't handle 1900 // them well yet. 1901 if (!I.getType()->isVectorTy()) { 1902 if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D)) 1903 return Match; 1904 if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C)) 1905 return Match; 1906 if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D)) 1907 return Match; 1908 if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C)) 1909 return Match; 1910 } 1911 1912 // ((A&~B)|(~A&B)) -> A^B 1913 if ((match(C, m_Not(m_Specific(D))) && 1914 match(B, m_Not(m_Specific(A))))) 1915 return BinaryOperator::CreateXor(A, D); 1916 // ((~B&A)|(~A&B)) -> A^B 1917 if ((match(A, m_Not(m_Specific(D))) && 1918 match(B, m_Not(m_Specific(C))))) 1919 return BinaryOperator::CreateXor(C, D); 1920 // ((A&~B)|(B&~A)) -> A^B 1921 if ((match(C, m_Not(m_Specific(B))) && 1922 match(D, m_Not(m_Specific(A))))) 1923 return BinaryOperator::CreateXor(A, B); 1924 // ((~B&A)|(B&~A)) -> A^B 1925 if ((match(A, m_Not(m_Specific(B))) && 1926 match(D, m_Not(m_Specific(C))))) 1927 return BinaryOperator::CreateXor(C, B); 1928 1929 // ((A|B)&1)|(B&-2) -> (A&1) | B 1930 if (match(A, m_Or(m_Value(V1), m_Specific(B))) || 1931 match(A, m_Or(m_Specific(B), m_Value(V1)))) { 1932 Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C); 1933 if (Ret) return Ret; 1934 } 1935 // (B&-2)|((A|B)&1) -> (A&1) | B 1936 if (match(B, m_Or(m_Specific(A), m_Value(V1))) || 1937 match(B, m_Or(m_Value(V1), m_Specific(A)))) { 1938 Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D); 1939 if (Ret) return Ret; 1940 } 1941 } 1942 1943 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts. 1944 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) { 1945 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0)) 1946 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && 1947 SI0->getOperand(1) == SI1->getOperand(1) && 1948 (SI0->hasOneUse() || SI1->hasOneUse())) { 1949 Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0), 1950 SI0->getName()); 1951 return BinaryOperator::Create(SI1->getOpcode(), NewOp, 1952 SI1->getOperand(1)); 1953 } 1954 } 1955 1956 // (~A | ~B) == (~(A & B)) - De Morgan's Law 1957 if (Value *Op0NotVal = dyn_castNotVal(Op0)) 1958 if (Value *Op1NotVal = dyn_castNotVal(Op1)) 1959 if (Op0->hasOneUse() && Op1->hasOneUse()) { 1960 Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal, 1961 I.getName()+".demorgan"); 1962 return BinaryOperator::CreateNot(And); 1963 } 1964 1965 // Canonicalize xor to the RHS. 1966 bool SwappedForXor = false; 1967 if (match(Op0, m_Xor(m_Value(), m_Value()))) { 1968 std::swap(Op0, Op1); 1969 SwappedForXor = true; 1970 } 1971 1972 // A | ( A ^ B) -> A | B 1973 // A | (~A ^ B) -> A | ~B 1974 // (A & B) | (A ^ B) 1975 if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) { 1976 if (Op0 == A || Op0 == B) 1977 return BinaryOperator::CreateOr(A, B); 1978 1979 if (match(Op0, m_And(m_Specific(A), m_Specific(B))) || 1980 match(Op0, m_And(m_Specific(B), m_Specific(A)))) 1981 return BinaryOperator::CreateOr(A, B); 1982 1983 if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) { 1984 Value *Not = Builder->CreateNot(B, B->getName()+".not"); 1985 return BinaryOperator::CreateOr(Not, Op0); 1986 } 1987 if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) { 1988 Value *Not = Builder->CreateNot(A, A->getName()+".not"); 1989 return BinaryOperator::CreateOr(Not, Op0); 1990 } 1991 } 1992 1993 // A | ~(A | B) -> A | ~B 1994 // A | ~(A ^ B) -> A | ~B 1995 if (match(Op1, m_Not(m_Value(A)))) 1996 if (BinaryOperator *B = dyn_cast<BinaryOperator>(A)) 1997 if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) && 1998 Op1->hasOneUse() && (B->getOpcode() == Instruction::Or || 1999 B->getOpcode() == Instruction::Xor)) { 2000 Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) : 2001 B->getOperand(0); 2002 Value *Not = Builder->CreateNot(NotOp, NotOp->getName()+".not"); 2003 return BinaryOperator::CreateOr(Not, Op0); 2004 } 2005 2006 if (SwappedForXor) 2007 std::swap(Op0, Op1); 2008 2009 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) 2010 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0))) 2011 if (Value *Res = FoldOrOfICmps(LHS, RHS)) 2012 return ReplaceInstUsesWith(I, Res); 2013 2014 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y) 2015 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) 2016 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) 2017 if (Value *Res = FoldOrOfFCmps(LHS, RHS)) 2018 return ReplaceInstUsesWith(I, Res); 2019 2020 // fold (or (cast A), (cast B)) -> (cast (or A, B)) 2021 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { 2022 CastInst *Op1C = dyn_cast<CastInst>(Op1); 2023 if (Op1C && Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ? 2024 Type *SrcTy = Op0C->getOperand(0)->getType(); 2025 if (SrcTy == Op1C->getOperand(0)->getType() && 2026 SrcTy->isIntOrIntVectorTy()) { 2027 Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0); 2028 2029 if ((!isa<ICmpInst>(Op0COp) || !isa<ICmpInst>(Op1COp)) && 2030 // Only do this if the casts both really cause code to be 2031 // generated. 2032 ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) && 2033 ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) { 2034 Value *NewOp = Builder->CreateOr(Op0COp, Op1COp, I.getName()); 2035 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); 2036 } 2037 2038 // If this is or(cast(icmp), cast(icmp)), try to fold this even if the 2039 // cast is otherwise not optimizable. This happens for vector sexts. 2040 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp)) 2041 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp)) 2042 if (Value *Res = FoldOrOfICmps(LHS, RHS)) 2043 return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); 2044 2045 // If this is or(cast(fcmp), cast(fcmp)), try to fold this even if the 2046 // cast is otherwise not optimizable. This happens for vector sexts. 2047 if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp)) 2048 if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp)) 2049 if (Value *Res = FoldOrOfFCmps(LHS, RHS)) 2050 return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); 2051 } 2052 } 2053 } 2054 2055 // or(sext(A), B) -> A ? -1 : B where A is an i1 2056 // or(A, sext(B)) -> B ? -1 : A where B is an i1 2057 if (match(Op0, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1)) 2058 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1); 2059 if (match(Op1, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1)) 2060 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0); 2061 2062 // Note: If we've gotten to the point of visiting the outer OR, then the 2063 // inner one couldn't be simplified. If it was a constant, then it won't 2064 // be simplified by a later pass either, so we try swapping the inner/outer 2065 // ORs in the hopes that we'll be able to simplify it this way. 2066 // (X|C) | V --> (X|V) | C 2067 if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) && 2068 match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) { 2069 Value *Inner = Builder->CreateOr(A, Op1); 2070 Inner->takeName(Op0); 2071 return BinaryOperator::CreateOr(Inner, C1); 2072 } 2073 2074 // Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D)) 2075 // Since this OR statement hasn't been optimized further yet, we hope 2076 // that this transformation will allow the new ORs to be optimized. 2077 { 2078 Value *X = 0, *Y = 0; 2079 if (Op0->hasOneUse() && Op1->hasOneUse() && 2080 match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) && 2081 match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) { 2082 Value *orTrue = Builder->CreateOr(A, C); 2083 Value *orFalse = Builder->CreateOr(B, D); 2084 return SelectInst::Create(X, orTrue, orFalse); 2085 } 2086 } 2087 2088 return Changed ? &I : 0; 2089 } 2090 2091 Instruction *InstCombiner::visitXor(BinaryOperator &I) { 2092 bool Changed = SimplifyAssociativeOrCommutative(I); 2093 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 2094 2095 if (Value *V = SimplifyXorInst(Op0, Op1, TD)) 2096 return ReplaceInstUsesWith(I, V); 2097 2098 // (A&B)^(A&C) -> A&(B^C) etc 2099 if (Value *V = SimplifyUsingDistributiveLaws(I)) 2100 return ReplaceInstUsesWith(I, V); 2101 2102 // See if we can simplify any instructions used by the instruction whose sole 2103 // purpose is to compute bits we don't care about. 2104 if (SimplifyDemandedInstructionBits(I)) 2105 return &I; 2106 2107 // Is this a ~ operation? 2108 if (Value *NotOp = dyn_castNotVal(&I)) { 2109 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) { 2110 if (Op0I->getOpcode() == Instruction::And || 2111 Op0I->getOpcode() == Instruction::Or) { 2112 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law 2113 // ~(~X | Y) === (X & ~Y) - De Morgan's Law 2114 if (dyn_castNotVal(Op0I->getOperand(1))) 2115 Op0I->swapOperands(); 2116 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { 2117 Value *NotY = 2118 Builder->CreateNot(Op0I->getOperand(1), 2119 Op0I->getOperand(1)->getName()+".not"); 2120 if (Op0I->getOpcode() == Instruction::And) 2121 return BinaryOperator::CreateOr(Op0NotVal, NotY); 2122 return BinaryOperator::CreateAnd(Op0NotVal, NotY); 2123 } 2124 2125 // ~(X & Y) --> (~X | ~Y) - De Morgan's Law 2126 // ~(X | Y) === (~X & ~Y) - De Morgan's Law 2127 if (isFreeToInvert(Op0I->getOperand(0)) && 2128 isFreeToInvert(Op0I->getOperand(1))) { 2129 Value *NotX = 2130 Builder->CreateNot(Op0I->getOperand(0), "notlhs"); 2131 Value *NotY = 2132 Builder->CreateNot(Op0I->getOperand(1), "notrhs"); 2133 if (Op0I->getOpcode() == Instruction::And) 2134 return BinaryOperator::CreateOr(NotX, NotY); 2135 return BinaryOperator::CreateAnd(NotX, NotY); 2136 } 2137 2138 } else if (Op0I->getOpcode() == Instruction::AShr) { 2139 // ~(~X >>s Y) --> (X >>s Y) 2140 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) 2141 return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1)); 2142 } 2143 } 2144 } 2145 2146 2147 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { 2148 if (RHS->isOne() && Op0->hasOneUse()) 2149 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B 2150 if (CmpInst *CI = dyn_cast<CmpInst>(Op0)) 2151 return CmpInst::Create(CI->getOpcode(), 2152 CI->getInversePredicate(), 2153 CI->getOperand(0), CI->getOperand(1)); 2154 2155 // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp). 2156 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { 2157 if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) { 2158 if (CI->hasOneUse() && Op0C->hasOneUse()) { 2159 Instruction::CastOps Opcode = Op0C->getOpcode(); 2160 if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) && 2161 (RHS == ConstantExpr::getCast(Opcode, 2162 ConstantInt::getTrue(I.getContext()), 2163 Op0C->getDestTy()))) { 2164 CI->setPredicate(CI->getInversePredicate()); 2165 return CastInst::Create(Opcode, CI, Op0C->getType()); 2166 } 2167 } 2168 } 2169 } 2170 2171 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { 2172 // ~(c-X) == X-c-1 == X+(-c-1) 2173 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue()) 2174 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) { 2175 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C); 2176 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C, 2177 ConstantInt::get(I.getType(), 1)); 2178 return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS); 2179 } 2180 2181 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) { 2182 if (Op0I->getOpcode() == Instruction::Add) { 2183 // ~(X-c) --> (-c-1)-X 2184 if (RHS->isAllOnesValue()) { 2185 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI); 2186 return BinaryOperator::CreateSub( 2187 ConstantExpr::getSub(NegOp0CI, 2188 ConstantInt::get(I.getType(), 1)), 2189 Op0I->getOperand(0)); 2190 } else if (RHS->getValue().isSignBit()) { 2191 // (X + C) ^ signbit -> (X + C + signbit) 2192 Constant *C = ConstantInt::get(I.getContext(), 2193 RHS->getValue() + Op0CI->getValue()); 2194 return BinaryOperator::CreateAdd(Op0I->getOperand(0), C); 2195 2196 } 2197 } else if (Op0I->getOpcode() == Instruction::Or) { 2198 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 2199 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) { 2200 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS); 2201 // Anything in both C1 and C2 is known to be zero, remove it from 2202 // NewRHS. 2203 Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS); 2204 NewRHS = ConstantExpr::getAnd(NewRHS, 2205 ConstantExpr::getNot(CommonBits)); 2206 Worklist.Add(Op0I); 2207 I.setOperand(0, Op0I->getOperand(0)); 2208 I.setOperand(1, NewRHS); 2209 return &I; 2210 } 2211 } else if (Op0I->getOpcode() == Instruction::LShr) { 2212 // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3) 2213 // E1 = "X ^ C1" 2214 BinaryOperator *E1; 2215 ConstantInt *C1; 2216 if (Op0I->hasOneUse() && 2217 (E1 = dyn_cast<BinaryOperator>(Op0I->getOperand(0))) && 2218 E1->getOpcode() == Instruction::Xor && 2219 (C1 = dyn_cast<ConstantInt>(E1->getOperand(1)))) { 2220 // fold (C1 >> C2) ^ C3 2221 ConstantInt *C2 = Op0CI, *C3 = RHS; 2222 APInt FoldConst = C1->getValue().lshr(C2->getValue()); 2223 FoldConst ^= C3->getValue(); 2224 // Prepare the two operands. 2225 Value *Opnd0 = Builder->CreateLShr(E1->getOperand(0), C2); 2226 Opnd0->takeName(Op0I); 2227 cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc()); 2228 Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst); 2229 2230 return BinaryOperator::CreateXor(Opnd0, FoldVal); 2231 } 2232 } 2233 } 2234 } 2235 2236 // Try to fold constant and into select arguments. 2237 if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) 2238 if (Instruction *R = FoldOpIntoSelect(I, SI)) 2239 return R; 2240 if (isa<PHINode>(Op0)) 2241 if (Instruction *NV = FoldOpIntoPhi(I)) 2242 return NV; 2243 } 2244 2245 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1); 2246 if (Op1I) { 2247 Value *A, *B; 2248 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) { 2249 if (A == Op0) { // B^(B|A) == (A|B)^B 2250 Op1I->swapOperands(); 2251 I.swapOperands(); 2252 std::swap(Op0, Op1); 2253 } else if (B == Op0) { // B^(A|B) == (A|B)^B 2254 I.swapOperands(); // Simplified below. 2255 std::swap(Op0, Op1); 2256 } 2257 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && 2258 Op1I->hasOneUse()){ 2259 if (A == Op0) { // A^(A&B) -> A^(B&A) 2260 Op1I->swapOperands(); 2261 std::swap(A, B); 2262 } 2263 if (B == Op0) { // A^(B&A) -> (B&A)^A 2264 I.swapOperands(); // Simplified below. 2265 std::swap(Op0, Op1); 2266 } 2267 } 2268 } 2269 2270 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0); 2271 if (Op0I) { 2272 Value *A, *B; 2273 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && 2274 Op0I->hasOneUse()) { 2275 if (A == Op1) // (B|A)^B == (A|B)^B 2276 std::swap(A, B); 2277 if (B == Op1) // (A|B)^B == A & ~B 2278 return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1)); 2279 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && 2280 Op0I->hasOneUse()){ 2281 if (A == Op1) // (A&B)^A -> (B&A)^A 2282 std::swap(A, B); 2283 if (B == Op1 && // (B&A)^A == ~B & A 2284 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C 2285 return BinaryOperator::CreateAnd(Builder->CreateNot(A), Op1); 2286 } 2287 } 2288 } 2289 2290 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts. 2291 if (Op0I && Op1I && Op0I->isShift() && 2292 Op0I->getOpcode() == Op1I->getOpcode() && 2293 Op0I->getOperand(1) == Op1I->getOperand(1) && 2294 (Op0I->hasOneUse() || Op1I->hasOneUse())) { 2295 Value *NewOp = 2296 Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0), 2297 Op0I->getName()); 2298 return BinaryOperator::Create(Op1I->getOpcode(), NewOp, 2299 Op1I->getOperand(1)); 2300 } 2301 2302 if (Op0I && Op1I) { 2303 Value *A, *B, *C, *D; 2304 // (A & B)^(A | B) -> A ^ B 2305 if (match(Op0I, m_And(m_Value(A), m_Value(B))) && 2306 match(Op1I, m_Or(m_Value(C), m_Value(D)))) { 2307 if ((A == C && B == D) || (A == D && B == C)) 2308 return BinaryOperator::CreateXor(A, B); 2309 } 2310 // (A | B)^(A & B) -> A ^ B 2311 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && 2312 match(Op1I, m_And(m_Value(C), m_Value(D)))) { 2313 if ((A == C && B == D) || (A == D && B == C)) 2314 return BinaryOperator::CreateXor(A, B); 2315 } 2316 } 2317 2318 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) 2319 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) 2320 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0))) 2321 if (PredicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) { 2322 if (LHS->getOperand(0) == RHS->getOperand(1) && 2323 LHS->getOperand(1) == RHS->getOperand(0)) 2324 LHS->swapOperands(); 2325 if (LHS->getOperand(0) == RHS->getOperand(0) && 2326 LHS->getOperand(1) == RHS->getOperand(1)) { 2327 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); 2328 unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS); 2329 bool isSigned = LHS->isSigned() || RHS->isSigned(); 2330 return ReplaceInstUsesWith(I, 2331 getNewICmpValue(isSigned, Code, Op0, Op1, 2332 Builder)); 2333 } 2334 } 2335 2336 // fold (xor (cast A), (cast B)) -> (cast (xor A, B)) 2337 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { 2338 if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) 2339 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind? 2340 Type *SrcTy = Op0C->getOperand(0)->getType(); 2341 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegerTy() && 2342 // Only do this if the casts both really cause code to be generated. 2343 ShouldOptimizeCast(Op0C->getOpcode(), Op0C->getOperand(0), 2344 I.getType()) && 2345 ShouldOptimizeCast(Op1C->getOpcode(), Op1C->getOperand(0), 2346 I.getType())) { 2347 Value *NewOp = Builder->CreateXor(Op0C->getOperand(0), 2348 Op1C->getOperand(0), I.getName()); 2349 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); 2350 } 2351 } 2352 } 2353 2354 return Changed ? &I : 0; 2355 } 2356