1 //===- ConstantFold.cpp - LLVM constant folder ----------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements folding of constants for LLVM. This implements the 11 // (internal) ConstantFold.h interface, which is used by the 12 // ConstantExpr::get* methods to automatically fold constants when possible. 13 // 14 // The current constant folding implementation is implemented in two pieces: the 15 // pieces that don't need TargetData, and the pieces that do. This is to avoid 16 // a dependence in VMCore on Target. 17 // 18 //===----------------------------------------------------------------------===// 19 20 #include "ConstantFold.h" 21 #include "llvm/Constants.h" 22 #include "llvm/Instructions.h" 23 #include "llvm/DerivedTypes.h" 24 #include "llvm/Function.h" 25 #include "llvm/GlobalAlias.h" 26 #include "llvm/GlobalVariable.h" 27 #include "llvm/Operator.h" 28 #include "llvm/ADT/SmallVector.h" 29 #include "llvm/Support/Compiler.h" 30 #include "llvm/Support/ErrorHandling.h" 31 #include "llvm/Support/GetElementPtrTypeIterator.h" 32 #include "llvm/Support/ManagedStatic.h" 33 #include "llvm/Support/MathExtras.h" 34 #include <limits> 35 using namespace llvm; 36 37 //===----------------------------------------------------------------------===// 38 // ConstantFold*Instruction Implementations 39 //===----------------------------------------------------------------------===// 40 41 /// BitCastConstantVector - Convert the specified vector Constant node to the 42 /// specified vector type. At this point, we know that the elements of the 43 /// input vector constant are all simple integer or FP values. 44 static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { 45 46 if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); 47 if (CV->isNullValue()) return Constant::getNullValue(DstTy); 48 49 // If this cast changes element count then we can't handle it here: 50 // doing so requires endianness information. This should be handled by 51 // Analysis/ConstantFolding.cpp 52 unsigned NumElts = DstTy->getNumElements(); 53 if (NumElts != CV->getType()->getVectorNumElements()) 54 return 0; 55 56 Type *DstEltTy = DstTy->getElementType(); 57 58 // Check to verify that all elements of the input are simple. 59 SmallVector<Constant*, 16> Result; 60 for (unsigned i = 0; i != NumElts; ++i) { 61 Constant *C = CV->getAggregateElement(i); 62 if (C == 0) return 0; 63 C = ConstantExpr::getBitCast(C, DstEltTy); 64 if (isa<ConstantExpr>(C)) return 0; 65 Result.push_back(C); 66 } 67 68 return ConstantVector::get(Result); 69 } 70 71 /// This function determines which opcode to use to fold two constant cast 72 /// expressions together. It uses CastInst::isEliminableCastPair to determine 73 /// the opcode. Consequently its just a wrapper around that function. 74 /// @brief Determine if it is valid to fold a cast of a cast 75 static unsigned 76 foldConstantCastPair( 77 unsigned opc, ///< opcode of the second cast constant expression 78 ConstantExpr *Op, ///< the first cast constant expression 79 Type *DstTy ///< desintation type of the first cast 80 ) { 81 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); 82 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); 83 assert(CastInst::isCast(opc) && "Invalid cast opcode"); 84 85 // The the types and opcodes for the two Cast constant expressions 86 Type *SrcTy = Op->getOperand(0)->getType(); 87 Type *MidTy = Op->getType(); 88 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); 89 Instruction::CastOps secondOp = Instruction::CastOps(opc); 90 91 // Let CastInst::isEliminableCastPair do the heavy lifting. 92 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, 93 Type::getInt64Ty(DstTy->getContext())); 94 } 95 96 static Constant *FoldBitCast(Constant *V, Type *DestTy) { 97 Type *SrcTy = V->getType(); 98 if (SrcTy == DestTy) 99 return V; // no-op cast 100 101 // Check to see if we are casting a pointer to an aggregate to a pointer to 102 // the first element. If so, return the appropriate GEP instruction. 103 if (PointerType *PTy = dyn_cast<PointerType>(V->getType())) 104 if (PointerType *DPTy = dyn_cast<PointerType>(DestTy)) 105 if (PTy->getAddressSpace() == DPTy->getAddressSpace() 106 && DPTy->getElementType()->isSized()) { 107 SmallVector<Value*, 8> IdxList; 108 Value *Zero = 109 Constant::getNullValue(Type::getInt32Ty(DPTy->getContext())); 110 IdxList.push_back(Zero); 111 Type *ElTy = PTy->getElementType(); 112 while (ElTy != DPTy->getElementType()) { 113 if (StructType *STy = dyn_cast<StructType>(ElTy)) { 114 if (STy->getNumElements() == 0) break; 115 ElTy = STy->getElementType(0); 116 IdxList.push_back(Zero); 117 } else if (SequentialType *STy = 118 dyn_cast<SequentialType>(ElTy)) { 119 if (ElTy->isPointerTy()) break; // Can't index into pointers! 120 ElTy = STy->getElementType(); 121 IdxList.push_back(Zero); 122 } else { 123 break; 124 } 125 } 126 127 if (ElTy == DPTy->getElementType()) 128 // This GEP is inbounds because all indices are zero. 129 return ConstantExpr::getInBoundsGetElementPtr(V, IdxList); 130 } 131 132 // Handle casts from one vector constant to another. We know that the src 133 // and dest type have the same size (otherwise its an illegal cast). 134 if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 135 if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 136 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 137 "Not cast between same sized vectors!"); 138 SrcTy = NULL; 139 // First, check for null. Undef is already handled. 140 if (isa<ConstantAggregateZero>(V)) 141 return Constant::getNullValue(DestTy); 142 143 // Handle ConstantVector and ConstantAggregateVector. 144 return BitCastConstantVector(V, DestPTy); 145 } 146 147 // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts 148 // This allows for other simplifications (although some of them 149 // can only be handled by Analysis/ConstantFolding.cpp). 150 if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) 151 return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); 152 } 153 154 // Finally, implement bitcast folding now. The code below doesn't handle 155 // bitcast right. 156 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 157 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 158 159 // Handle integral constant input. 160 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 161 if (DestTy->isIntegerTy()) 162 // Integral -> Integral. This is a no-op because the bit widths must 163 // be the same. Consequently, we just fold to V. 164 return V; 165 166 if (DestTy->isFloatingPointTy()) 167 return ConstantFP::get(DestTy->getContext(), 168 APFloat(CI->getValue(), 169 !DestTy->isPPC_FP128Ty())); 170 171 // Otherwise, can't fold this (vector?) 172 return 0; 173 } 174 175 // Handle ConstantFP input: FP -> Integral. 176 if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) 177 return ConstantInt::get(FP->getContext(), 178 FP->getValueAPF().bitcastToAPInt()); 179 180 return 0; 181 } 182 183 184 /// ExtractConstantBytes - V is an integer constant which only has a subset of 185 /// its bytes used. The bytes used are indicated by ByteStart (which is the 186 /// first byte used, counting from the least significant byte) and ByteSize, 187 /// which is the number of bytes used. 188 /// 189 /// This function analyzes the specified constant to see if the specified byte 190 /// range can be returned as a simplified constant. If so, the constant is 191 /// returned, otherwise null is returned. 192 /// 193 static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, 194 unsigned ByteSize) { 195 assert(C->getType()->isIntegerTy() && 196 (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && 197 "Non-byte sized integer input"); 198 unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; 199 assert(ByteSize && "Must be accessing some piece"); 200 assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); 201 assert(ByteSize != CSize && "Should not extract everything"); 202 203 // Constant Integers are simple. 204 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { 205 APInt V = CI->getValue(); 206 if (ByteStart) 207 V = V.lshr(ByteStart*8); 208 V = V.trunc(ByteSize*8); 209 return ConstantInt::get(CI->getContext(), V); 210 } 211 212 // In the input is a constant expr, we might be able to recursively simplify. 213 // If not, we definitely can't do anything. 214 ConstantExpr *CE = dyn_cast<ConstantExpr>(C); 215 if (CE == 0) return 0; 216 217 switch (CE->getOpcode()) { 218 default: return 0; 219 case Instruction::Or: { 220 Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 221 if (RHS == 0) 222 return 0; 223 224 // X | -1 -> -1. 225 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) 226 if (RHSC->isAllOnesValue()) 227 return RHSC; 228 229 Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 230 if (LHS == 0) 231 return 0; 232 return ConstantExpr::getOr(LHS, RHS); 233 } 234 case Instruction::And: { 235 Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 236 if (RHS == 0) 237 return 0; 238 239 // X & 0 -> 0. 240 if (RHS->isNullValue()) 241 return RHS; 242 243 Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 244 if (LHS == 0) 245 return 0; 246 return ConstantExpr::getAnd(LHS, RHS); 247 } 248 case Instruction::LShr: { 249 ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 250 if (Amt == 0) 251 return 0; 252 unsigned ShAmt = Amt->getZExtValue(); 253 // Cannot analyze non-byte shifts. 254 if ((ShAmt & 7) != 0) 255 return 0; 256 ShAmt >>= 3; 257 258 // If the extract is known to be all zeros, return zero. 259 if (ByteStart >= CSize-ShAmt) 260 return Constant::getNullValue(IntegerType::get(CE->getContext(), 261 ByteSize*8)); 262 // If the extract is known to be fully in the input, extract it. 263 if (ByteStart+ByteSize+ShAmt <= CSize) 264 return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); 265 266 // TODO: Handle the 'partially zero' case. 267 return 0; 268 } 269 270 case Instruction::Shl: { 271 ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 272 if (Amt == 0) 273 return 0; 274 unsigned ShAmt = Amt->getZExtValue(); 275 // Cannot analyze non-byte shifts. 276 if ((ShAmt & 7) != 0) 277 return 0; 278 ShAmt >>= 3; 279 280 // If the extract is known to be all zeros, return zero. 281 if (ByteStart+ByteSize <= ShAmt) 282 return Constant::getNullValue(IntegerType::get(CE->getContext(), 283 ByteSize*8)); 284 // If the extract is known to be fully in the input, extract it. 285 if (ByteStart >= ShAmt) 286 return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); 287 288 // TODO: Handle the 'partially zero' case. 289 return 0; 290 } 291 292 case Instruction::ZExt: { 293 unsigned SrcBitSize = 294 cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); 295 296 // If extracting something that is completely zero, return 0. 297 if (ByteStart*8 >= SrcBitSize) 298 return Constant::getNullValue(IntegerType::get(CE->getContext(), 299 ByteSize*8)); 300 301 // If exactly extracting the input, return it. 302 if (ByteStart == 0 && ByteSize*8 == SrcBitSize) 303 return CE->getOperand(0); 304 305 // If extracting something completely in the input, if if the input is a 306 // multiple of 8 bits, recurse. 307 if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) 308 return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); 309 310 // Otherwise, if extracting a subset of the input, which is not multiple of 311 // 8 bits, do a shift and trunc to get the bits. 312 if ((ByteStart+ByteSize)*8 < SrcBitSize) { 313 assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); 314 Constant *Res = CE->getOperand(0); 315 if (ByteStart) 316 Res = ConstantExpr::getLShr(Res, 317 ConstantInt::get(Res->getType(), ByteStart*8)); 318 return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), 319 ByteSize*8)); 320 } 321 322 // TODO: Handle the 'partially zero' case. 323 return 0; 324 } 325 } 326 } 327 328 /// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof 329 /// on Ty, with any known factors factored out. If Folded is false, 330 /// return null if no factoring was possible, to avoid endlessly 331 /// bouncing an unfoldable expression back into the top-level folder. 332 /// 333 static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, 334 bool Folded) { 335 if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 336 Constant *N = ConstantInt::get(DestTy, ATy->getNumElements()); 337 Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 338 return ConstantExpr::getNUWMul(E, N); 339 } 340 341 if (StructType *STy = dyn_cast<StructType>(Ty)) 342 if (!STy->isPacked()) { 343 unsigned NumElems = STy->getNumElements(); 344 // An empty struct has size zero. 345 if (NumElems == 0) 346 return ConstantExpr::getNullValue(DestTy); 347 // Check for a struct with all members having the same size. 348 Constant *MemberSize = 349 getFoldedSizeOf(STy->getElementType(0), DestTy, true); 350 bool AllSame = true; 351 for (unsigned i = 1; i != NumElems; ++i) 352 if (MemberSize != 353 getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 354 AllSame = false; 355 break; 356 } 357 if (AllSame) { 358 Constant *N = ConstantInt::get(DestTy, NumElems); 359 return ConstantExpr::getNUWMul(MemberSize, N); 360 } 361 } 362 363 // Pointer size doesn't depend on the pointee type, so canonicalize them 364 // to an arbitrary pointee. 365 if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 366 if (!PTy->getElementType()->isIntegerTy(1)) 367 return 368 getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1), 369 PTy->getAddressSpace()), 370 DestTy, true); 371 372 // If there's no interesting folding happening, bail so that we don't create 373 // a constant that looks like it needs folding but really doesn't. 374 if (!Folded) 375 return 0; 376 377 // Base case: Get a regular sizeof expression. 378 Constant *C = ConstantExpr::getSizeOf(Ty); 379 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 380 DestTy, false), 381 C, DestTy); 382 return C; 383 } 384 385 /// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof 386 /// on Ty, with any known factors factored out. If Folded is false, 387 /// return null if no factoring was possible, to avoid endlessly 388 /// bouncing an unfoldable expression back into the top-level folder. 389 /// 390 static Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, 391 bool Folded) { 392 // The alignment of an array is equal to the alignment of the 393 // array element. Note that this is not always true for vectors. 394 if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 395 Constant *C = ConstantExpr::getAlignOf(ATy->getElementType()); 396 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 397 DestTy, 398 false), 399 C, DestTy); 400 return C; 401 } 402 403 if (StructType *STy = dyn_cast<StructType>(Ty)) { 404 // Packed structs always have an alignment of 1. 405 if (STy->isPacked()) 406 return ConstantInt::get(DestTy, 1); 407 408 // Otherwise, struct alignment is the maximum alignment of any member. 409 // Without target data, we can't compare much, but we can check to see 410 // if all the members have the same alignment. 411 unsigned NumElems = STy->getNumElements(); 412 // An empty struct has minimal alignment. 413 if (NumElems == 0) 414 return ConstantInt::get(DestTy, 1); 415 // Check for a struct with all members having the same alignment. 416 Constant *MemberAlign = 417 getFoldedAlignOf(STy->getElementType(0), DestTy, true); 418 bool AllSame = true; 419 for (unsigned i = 1; i != NumElems; ++i) 420 if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) { 421 AllSame = false; 422 break; 423 } 424 if (AllSame) 425 return MemberAlign; 426 } 427 428 // Pointer alignment doesn't depend on the pointee type, so canonicalize them 429 // to an arbitrary pointee. 430 if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 431 if (!PTy->getElementType()->isIntegerTy(1)) 432 return 433 getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(), 434 1), 435 PTy->getAddressSpace()), 436 DestTy, true); 437 438 // If there's no interesting folding happening, bail so that we don't create 439 // a constant that looks like it needs folding but really doesn't. 440 if (!Folded) 441 return 0; 442 443 // Base case: Get a regular alignof expression. 444 Constant *C = ConstantExpr::getAlignOf(Ty); 445 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 446 DestTy, false), 447 C, DestTy); 448 return C; 449 } 450 451 /// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof 452 /// on Ty and FieldNo, with any known factors factored out. If Folded is false, 453 /// return null if no factoring was possible, to avoid endlessly 454 /// bouncing an unfoldable expression back into the top-level folder. 455 /// 456 static Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, 457 Type *DestTy, 458 bool Folded) { 459 if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 460 Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false, 461 DestTy, false), 462 FieldNo, DestTy); 463 Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 464 return ConstantExpr::getNUWMul(E, N); 465 } 466 467 if (StructType *STy = dyn_cast<StructType>(Ty)) 468 if (!STy->isPacked()) { 469 unsigned NumElems = STy->getNumElements(); 470 // An empty struct has no members. 471 if (NumElems == 0) 472 return 0; 473 // Check for a struct with all members having the same size. 474 Constant *MemberSize = 475 getFoldedSizeOf(STy->getElementType(0), DestTy, true); 476 bool AllSame = true; 477 for (unsigned i = 1; i != NumElems; ++i) 478 if (MemberSize != 479 getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 480 AllSame = false; 481 break; 482 } 483 if (AllSame) { 484 Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, 485 false, 486 DestTy, 487 false), 488 FieldNo, DestTy); 489 return ConstantExpr::getNUWMul(MemberSize, N); 490 } 491 } 492 493 // If there's no interesting folding happening, bail so that we don't create 494 // a constant that looks like it needs folding but really doesn't. 495 if (!Folded) 496 return 0; 497 498 // Base case: Get a regular offsetof expression. 499 Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo); 500 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 501 DestTy, false), 502 C, DestTy); 503 return C; 504 } 505 506 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, 507 Type *DestTy) { 508 if (isa<UndefValue>(V)) { 509 // zext(undef) = 0, because the top bits will be zero. 510 // sext(undef) = 0, because the top bits will all be the same. 511 // [us]itofp(undef) = 0, because the result value is bounded. 512 if (opc == Instruction::ZExt || opc == Instruction::SExt || 513 opc == Instruction::UIToFP || opc == Instruction::SIToFP) 514 return Constant::getNullValue(DestTy); 515 return UndefValue::get(DestTy); 516 } 517 518 // No compile-time operations on this type yet. 519 if (V->getType()->isPPC_FP128Ty() || DestTy->isPPC_FP128Ty()) 520 return 0; 521 522 if (V->isNullValue() && !DestTy->isX86_MMXTy()) 523 return Constant::getNullValue(DestTy); 524 525 // If the cast operand is a constant expression, there's a few things we can 526 // do to try to simplify it. 527 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 528 if (CE->isCast()) { 529 // Try hard to fold cast of cast because they are often eliminable. 530 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 531 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 532 } else if (CE->getOpcode() == Instruction::GetElementPtr) { 533 // If all of the indexes in the GEP are null values, there is no pointer 534 // adjustment going on. We might as well cast the source pointer. 535 bool isAllNull = true; 536 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 537 if (!CE->getOperand(i)->isNullValue()) { 538 isAllNull = false; 539 break; 540 } 541 if (isAllNull) 542 // This is casting one pointer type to another, always BitCast 543 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 544 } 545 } 546 547 // If the cast operand is a constant vector, perform the cast by 548 // operating on each element. In the cast of bitcasts, the element 549 // count may be mismatched; don't attempt to handle that here. 550 if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) && 551 DestTy->isVectorTy() && 552 DestTy->getVectorNumElements() == V->getType()->getVectorNumElements()) { 553 SmallVector<Constant*, 16> res; 554 VectorType *DestVecTy = cast<VectorType>(DestTy); 555 Type *DstEltTy = DestVecTy->getElementType(); 556 for (unsigned i = 0, e = V->getType()->getVectorNumElements(); i != e; ++i) 557 res.push_back(ConstantExpr::getCast(opc, 558 V->getAggregateElement(i), DstEltTy)); 559 return ConstantVector::get(res); 560 } 561 562 // We actually have to do a cast now. Perform the cast according to the 563 // opcode specified. 564 switch (opc) { 565 default: 566 llvm_unreachable("Failed to cast constant expression"); 567 case Instruction::FPTrunc: 568 case Instruction::FPExt: 569 if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 570 bool ignored; 571 APFloat Val = FPC->getValueAPF(); 572 Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf : 573 DestTy->isFloatTy() ? APFloat::IEEEsingle : 574 DestTy->isDoubleTy() ? APFloat::IEEEdouble : 575 DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : 576 DestTy->isFP128Ty() ? APFloat::IEEEquad : 577 APFloat::Bogus, 578 APFloat::rmNearestTiesToEven, &ignored); 579 return ConstantFP::get(V->getContext(), Val); 580 } 581 return 0; // Can't fold. 582 case Instruction::FPToUI: 583 case Instruction::FPToSI: 584 if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 585 const APFloat &V = FPC->getValueAPF(); 586 bool ignored; 587 uint64_t x[2]; 588 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 589 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 590 APFloat::rmTowardZero, &ignored); 591 APInt Val(DestBitWidth, x); 592 return ConstantInt::get(FPC->getContext(), Val); 593 } 594 return 0; // Can't fold. 595 case Instruction::IntToPtr: //always treated as unsigned 596 if (V->isNullValue()) // Is it an integral null value? 597 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 598 return 0; // Other pointer types cannot be casted 599 case Instruction::PtrToInt: // always treated as unsigned 600 // Is it a null pointer value? 601 if (V->isNullValue()) 602 return ConstantInt::get(DestTy, 0); 603 // If this is a sizeof-like expression, pull out multiplications by 604 // known factors to expose them to subsequent folding. If it's an 605 // alignof-like expression, factor out known factors. 606 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 607 if (CE->getOpcode() == Instruction::GetElementPtr && 608 CE->getOperand(0)->isNullValue()) { 609 Type *Ty = 610 cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); 611 if (CE->getNumOperands() == 2) { 612 // Handle a sizeof-like expression. 613 Constant *Idx = CE->getOperand(1); 614 bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne(); 615 if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) { 616 Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true, 617 DestTy, false), 618 Idx, DestTy); 619 return ConstantExpr::getMul(C, Idx); 620 } 621 } else if (CE->getNumOperands() == 3 && 622 CE->getOperand(1)->isNullValue()) { 623 // Handle an alignof-like expression. 624 if (StructType *STy = dyn_cast<StructType>(Ty)) 625 if (!STy->isPacked()) { 626 ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2)); 627 if (CI->isOne() && 628 STy->getNumElements() == 2 && 629 STy->getElementType(0)->isIntegerTy(1)) { 630 return getFoldedAlignOf(STy->getElementType(1), DestTy, false); 631 } 632 } 633 // Handle an offsetof-like expression. 634 if (Ty->isStructTy() || Ty->isArrayTy()) { 635 if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2), 636 DestTy, false)) 637 return C; 638 } 639 } 640 } 641 // Other pointer types cannot be casted 642 return 0; 643 case Instruction::UIToFP: 644 case Instruction::SIToFP: 645 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 646 APInt api = CI->getValue(); 647 APFloat apf(APInt::getNullValue(DestTy->getPrimitiveSizeInBits()), true); 648 (void)apf.convertFromAPInt(api, 649 opc==Instruction::SIToFP, 650 APFloat::rmNearestTiesToEven); 651 return ConstantFP::get(V->getContext(), apf); 652 } 653 return 0; 654 case Instruction::ZExt: 655 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 656 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 657 return ConstantInt::get(V->getContext(), 658 CI->getValue().zext(BitWidth)); 659 } 660 return 0; 661 case Instruction::SExt: 662 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 663 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 664 return ConstantInt::get(V->getContext(), 665 CI->getValue().sext(BitWidth)); 666 } 667 return 0; 668 case Instruction::Trunc: { 669 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 670 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 671 return ConstantInt::get(V->getContext(), 672 CI->getValue().trunc(DestBitWidth)); 673 } 674 675 // The input must be a constantexpr. See if we can simplify this based on 676 // the bytes we are demanding. Only do this if the source and dest are an 677 // even multiple of a byte. 678 if ((DestBitWidth & 7) == 0 && 679 (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) 680 if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) 681 return Res; 682 683 return 0; 684 } 685 case Instruction::BitCast: 686 return FoldBitCast(V, DestTy); 687 } 688 } 689 690 Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond, 691 Constant *V1, Constant *V2) { 692 // Check for i1 and vector true/false conditions. 693 if (Cond->isNullValue()) return V2; 694 if (Cond->isAllOnesValue()) return V1; 695 696 // If the condition is a vector constant, fold the result elementwise. 697 if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) { 698 SmallVector<Constant*, 16> Result; 699 for (unsigned i = 0, e = V1->getType()->getVectorNumElements(); i != e;++i){ 700 ConstantInt *Cond = dyn_cast<ConstantInt>(CondV->getOperand(i)); 701 if (Cond == 0) break; 702 703 Constant *Res = (Cond->getZExtValue() ? V2 : V1)->getAggregateElement(i); 704 if (Res == 0) break; 705 Result.push_back(Res); 706 } 707 708 // If we were able to build the vector, return it. 709 if (Result.size() == V1->getType()->getVectorNumElements()) 710 return ConstantVector::get(Result); 711 } 712 713 if (isa<UndefValue>(Cond)) { 714 if (isa<UndefValue>(V1)) return V1; 715 return V2; 716 } 717 if (isa<UndefValue>(V1)) return V2; 718 if (isa<UndefValue>(V2)) return V1; 719 if (V1 == V2) return V1; 720 721 if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) { 722 if (TrueVal->getOpcode() == Instruction::Select) 723 if (TrueVal->getOperand(0) == Cond) 724 return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2); 725 } 726 if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) { 727 if (FalseVal->getOpcode() == Instruction::Select) 728 if (FalseVal->getOperand(0) == Cond) 729 return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2)); 730 } 731 732 return 0; 733 } 734 735 Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val, 736 Constant *Idx) { 737 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 738 return UndefValue::get(Val->getType()->getVectorElementType()); 739 if (Val->isNullValue()) // ee(zero, x) -> zero 740 return Constant::getNullValue(Val->getType()->getVectorElementType()); 741 // ee({w,x,y,z}, undef) -> undef 742 if (isa<UndefValue>(Idx)) 743 return UndefValue::get(Val->getType()->getVectorElementType()); 744 745 if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 746 uint64_t Index = CIdx->getZExtValue(); 747 // ee({w,x,y,z}, wrong_value) -> undef 748 if (Index >= Val->getType()->getVectorNumElements()) 749 return UndefValue::get(Val->getType()->getVectorElementType()); 750 return Val->getAggregateElement(Index); 751 } 752 return 0; 753 } 754 755 Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val, 756 Constant *Elt, 757 Constant *Idx) { 758 ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 759 if (!CIdx) return 0; 760 const APInt &IdxVal = CIdx->getValue(); 761 762 SmallVector<Constant*, 16> Result; 763 for (unsigned i = 0, e = Val->getType()->getVectorNumElements(); i != e; ++i){ 764 if (i == IdxVal) { 765 Result.push_back(Elt); 766 continue; 767 } 768 769 if (Constant *C = Val->getAggregateElement(i)) 770 Result.push_back(C); 771 else 772 return 0; 773 } 774 775 return ConstantVector::get(Result); 776 } 777 778 Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, 779 Constant *V2, 780 Constant *Mask) { 781 unsigned MaskNumElts = Mask->getType()->getVectorNumElements(); 782 Type *EltTy = V1->getType()->getVectorElementType(); 783 784 // Undefined shuffle mask -> undefined value. 785 if (isa<UndefValue>(Mask)) 786 return UndefValue::get(VectorType::get(EltTy, MaskNumElts)); 787 788 // Don't break the bitcode reader hack. 789 if (isa<ConstantExpr>(Mask)) return 0; 790 791 unsigned SrcNumElts = V1->getType()->getVectorNumElements(); 792 793 // Loop over the shuffle mask, evaluating each element. 794 SmallVector<Constant*, 32> Result; 795 for (unsigned i = 0; i != MaskNumElts; ++i) { 796 int Elt = ShuffleVectorInst::getMaskValue(Mask, i); 797 if (Elt == -1) { 798 Result.push_back(UndefValue::get(EltTy)); 799 continue; 800 } 801 Constant *InElt; 802 if (unsigned(Elt) >= SrcNumElts*2) 803 InElt = UndefValue::get(EltTy); 804 else if (unsigned(Elt) >= SrcNumElts) 805 InElt = V2->getAggregateElement(Elt - SrcNumElts); 806 else 807 InElt = V1->getAggregateElement(Elt); 808 if (InElt == 0) return 0; 809 Result.push_back(InElt); 810 } 811 812 return ConstantVector::get(Result); 813 } 814 815 Constant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg, 816 ArrayRef<unsigned> Idxs) { 817 // Base case: no indices, so return the entire value. 818 if (Idxs.empty()) 819 return Agg; 820 821 if (Constant *C = Agg->getAggregateElement(Idxs[0])) 822 return ConstantFoldExtractValueInstruction(C, Idxs.slice(1)); 823 824 return 0; 825 } 826 827 Constant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg, 828 Constant *Val, 829 ArrayRef<unsigned> Idxs) { 830 // Base case: no indices, so replace the entire value. 831 if (Idxs.empty()) 832 return Val; 833 834 unsigned NumElts; 835 if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 836 NumElts = ST->getNumElements(); 837 else if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 838 NumElts = AT->getNumElements(); 839 else 840 NumElts = AT->getVectorNumElements(); 841 842 SmallVector<Constant*, 32> Result; 843 for (unsigned i = 0; i != NumElts; ++i) { 844 Constant *C = Agg->getAggregateElement(i); 845 if (C == 0) return 0; 846 847 if (Idxs[0] == i) 848 C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1)); 849 850 Result.push_back(C); 851 } 852 853 if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 854 return ConstantStruct::get(ST, Result); 855 if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 856 return ConstantArray::get(AT, Result); 857 return ConstantVector::get(Result); 858 } 859 860 861 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, 862 Constant *C1, Constant *C2) { 863 // No compile-time operations on this type yet. 864 if (C1->getType()->isPPC_FP128Ty()) 865 return 0; 866 867 // Handle UndefValue up front. 868 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 869 switch (Opcode) { 870 case Instruction::Xor: 871 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 872 // Handle undef ^ undef -> 0 special case. This is a common 873 // idiom (misuse). 874 return Constant::getNullValue(C1->getType()); 875 // Fallthrough 876 case Instruction::Add: 877 case Instruction::Sub: 878 return UndefValue::get(C1->getType()); 879 case Instruction::And: 880 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef 881 return C1; 882 return Constant::getNullValue(C1->getType()); // undef & X -> 0 883 case Instruction::Mul: { 884 ConstantInt *CI; 885 // X * undef -> undef if X is odd or undef 886 if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) || 887 ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) || 888 (isa<UndefValue>(C1) && isa<UndefValue>(C2))) 889 return UndefValue::get(C1->getType()); 890 891 // X * undef -> 0 otherwise 892 return Constant::getNullValue(C1->getType()); 893 } 894 case Instruction::UDiv: 895 case Instruction::SDiv: 896 // undef / 1 -> undef 897 if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv) 898 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) 899 if (CI2->isOne()) 900 return C1; 901 // FALL THROUGH 902 case Instruction::URem: 903 case Instruction::SRem: 904 if (!isa<UndefValue>(C2)) // undef / X -> 0 905 return Constant::getNullValue(C1->getType()); 906 return C2; // X / undef -> undef 907 case Instruction::Or: // X | undef -> -1 908 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef 909 return C1; 910 return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 911 case Instruction::LShr: 912 if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 913 return C1; // undef lshr undef -> undef 914 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 915 // undef lshr X -> 0 916 case Instruction::AShr: 917 if (!isa<UndefValue>(C2)) // undef ashr X --> all ones 918 return Constant::getAllOnesValue(C1->getType()); 919 else if (isa<UndefValue>(C1)) 920 return C1; // undef ashr undef -> undef 921 else 922 return C1; // X ashr undef --> X 923 case Instruction::Shl: 924 if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 925 return C1; // undef shl undef -> undef 926 // undef << X -> 0 or X << undef -> 0 927 return Constant::getNullValue(C1->getType()); 928 } 929 } 930 931 // Handle simplifications when the RHS is a constant int. 932 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 933 switch (Opcode) { 934 case Instruction::Add: 935 if (CI2->equalsInt(0)) return C1; // X + 0 == X 936 break; 937 case Instruction::Sub: 938 if (CI2->equalsInt(0)) return C1; // X - 0 == X 939 break; 940 case Instruction::Mul: 941 if (CI2->equalsInt(0)) return C2; // X * 0 == 0 942 if (CI2->equalsInt(1)) 943 return C1; // X * 1 == X 944 break; 945 case Instruction::UDiv: 946 case Instruction::SDiv: 947 if (CI2->equalsInt(1)) 948 return C1; // X / 1 == X 949 if (CI2->equalsInt(0)) 950 return UndefValue::get(CI2->getType()); // X / 0 == undef 951 break; 952 case Instruction::URem: 953 case Instruction::SRem: 954 if (CI2->equalsInt(1)) 955 return Constant::getNullValue(CI2->getType()); // X % 1 == 0 956 if (CI2->equalsInt(0)) 957 return UndefValue::get(CI2->getType()); // X % 0 == undef 958 break; 959 case Instruction::And: 960 if (CI2->isZero()) return C2; // X & 0 == 0 961 if (CI2->isAllOnesValue()) 962 return C1; // X & -1 == X 963 964 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 965 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 966 if (CE1->getOpcode() == Instruction::ZExt) { 967 unsigned DstWidth = CI2->getType()->getBitWidth(); 968 unsigned SrcWidth = 969 CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); 970 APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); 971 if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) 972 return C1; 973 } 974 975 // If and'ing the address of a global with a constant, fold it. 976 if (CE1->getOpcode() == Instruction::PtrToInt && 977 isa<GlobalValue>(CE1->getOperand(0))) { 978 GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); 979 980 // Functions are at least 4-byte aligned. 981 unsigned GVAlign = GV->getAlignment(); 982 if (isa<Function>(GV)) 983 GVAlign = std::max(GVAlign, 4U); 984 985 if (GVAlign > 1) { 986 unsigned DstWidth = CI2->getType()->getBitWidth(); 987 unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); 988 APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); 989 990 // If checking bits we know are clear, return zero. 991 if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) 992 return Constant::getNullValue(CI2->getType()); 993 } 994 } 995 } 996 break; 997 case Instruction::Or: 998 if (CI2->equalsInt(0)) return C1; // X | 0 == X 999 if (CI2->isAllOnesValue()) 1000 return C2; // X | -1 == -1 1001 break; 1002 case Instruction::Xor: 1003 if (CI2->equalsInt(0)) return C1; // X ^ 0 == X 1004 1005 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1006 switch (CE1->getOpcode()) { 1007 default: break; 1008 case Instruction::ICmp: 1009 case Instruction::FCmp: 1010 // cmp pred ^ true -> cmp !pred 1011 assert(CI2->equalsInt(1)); 1012 CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); 1013 pred = CmpInst::getInversePredicate(pred); 1014 return ConstantExpr::getCompare(pred, CE1->getOperand(0), 1015 CE1->getOperand(1)); 1016 } 1017 } 1018 break; 1019 case Instruction::AShr: 1020 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 1021 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) 1022 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 1023 return ConstantExpr::getLShr(C1, C2); 1024 break; 1025 } 1026 } else if (isa<ConstantInt>(C1)) { 1027 // If C1 is a ConstantInt and C2 is not, swap the operands. 1028 if (Instruction::isCommutative(Opcode)) 1029 return ConstantExpr::get(Opcode, C2, C1); 1030 } 1031 1032 // At this point we know neither constant is an UndefValue. 1033 if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 1034 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 1035 const APInt &C1V = CI1->getValue(); 1036 const APInt &C2V = CI2->getValue(); 1037 switch (Opcode) { 1038 default: 1039 break; 1040 case Instruction::Add: 1041 return ConstantInt::get(CI1->getContext(), C1V + C2V); 1042 case Instruction::Sub: 1043 return ConstantInt::get(CI1->getContext(), C1V - C2V); 1044 case Instruction::Mul: 1045 return ConstantInt::get(CI1->getContext(), C1V * C2V); 1046 case Instruction::UDiv: 1047 assert(!CI2->isNullValue() && "Div by zero handled above"); 1048 return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V)); 1049 case Instruction::SDiv: 1050 assert(!CI2->isNullValue() && "Div by zero handled above"); 1051 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1052 return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef 1053 return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V)); 1054 case Instruction::URem: 1055 assert(!CI2->isNullValue() && "Div by zero handled above"); 1056 return ConstantInt::get(CI1->getContext(), C1V.urem(C2V)); 1057 case Instruction::SRem: 1058 assert(!CI2->isNullValue() && "Div by zero handled above"); 1059 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1060 return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef 1061 return ConstantInt::get(CI1->getContext(), C1V.srem(C2V)); 1062 case Instruction::And: 1063 return ConstantInt::get(CI1->getContext(), C1V & C2V); 1064 case Instruction::Or: 1065 return ConstantInt::get(CI1->getContext(), C1V | C2V); 1066 case Instruction::Xor: 1067 return ConstantInt::get(CI1->getContext(), C1V ^ C2V); 1068 case Instruction::Shl: { 1069 uint32_t shiftAmt = C2V.getZExtValue(); 1070 if (shiftAmt < C1V.getBitWidth()) 1071 return ConstantInt::get(CI1->getContext(), C1V.shl(shiftAmt)); 1072 else 1073 return UndefValue::get(C1->getType()); // too big shift is undef 1074 } 1075 case Instruction::LShr: { 1076 uint32_t shiftAmt = C2V.getZExtValue(); 1077 if (shiftAmt < C1V.getBitWidth()) 1078 return ConstantInt::get(CI1->getContext(), C1V.lshr(shiftAmt)); 1079 else 1080 return UndefValue::get(C1->getType()); // too big shift is undef 1081 } 1082 case Instruction::AShr: { 1083 uint32_t shiftAmt = C2V.getZExtValue(); 1084 if (shiftAmt < C1V.getBitWidth()) 1085 return ConstantInt::get(CI1->getContext(), C1V.ashr(shiftAmt)); 1086 else 1087 return UndefValue::get(C1->getType()); // too big shift is undef 1088 } 1089 } 1090 } 1091 1092 switch (Opcode) { 1093 case Instruction::SDiv: 1094 case Instruction::UDiv: 1095 case Instruction::URem: 1096 case Instruction::SRem: 1097 case Instruction::LShr: 1098 case Instruction::AShr: 1099 case Instruction::Shl: 1100 if (CI1->equalsInt(0)) return C1; 1101 break; 1102 default: 1103 break; 1104 } 1105 } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 1106 if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 1107 APFloat C1V = CFP1->getValueAPF(); 1108 APFloat C2V = CFP2->getValueAPF(); 1109 APFloat C3V = C1V; // copy for modification 1110 switch (Opcode) { 1111 default: 1112 break; 1113 case Instruction::FAdd: 1114 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 1115 return ConstantFP::get(C1->getContext(), C3V); 1116 case Instruction::FSub: 1117 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 1118 return ConstantFP::get(C1->getContext(), C3V); 1119 case Instruction::FMul: 1120 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 1121 return ConstantFP::get(C1->getContext(), C3V); 1122 case Instruction::FDiv: 1123 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 1124 return ConstantFP::get(C1->getContext(), C3V); 1125 case Instruction::FRem: 1126 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); 1127 return ConstantFP::get(C1->getContext(), C3V); 1128 } 1129 } 1130 } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 1131 // Perform elementwise folding. 1132 SmallVector<Constant*, 16> Result; 1133 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1134 Constant *LHS = C1->getAggregateElement(i); 1135 Constant *RHS = C2->getAggregateElement(i); 1136 if (LHS == 0 || RHS == 0) break; 1137 1138 Result.push_back(ConstantExpr::get(Opcode, LHS, RHS)); 1139 } 1140 1141 if (Result.size() == VTy->getNumElements()) 1142 return ConstantVector::get(Result); 1143 } 1144 1145 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1146 // There are many possible foldings we could do here. We should probably 1147 // at least fold add of a pointer with an integer into the appropriate 1148 // getelementptr. This will improve alias analysis a bit. 1149 1150 // Given ((a + b) + c), if (b + c) folds to something interesting, return 1151 // (a + (b + c)). 1152 if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) { 1153 Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2); 1154 if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode) 1155 return ConstantExpr::get(Opcode, CE1->getOperand(0), T); 1156 } 1157 } else if (isa<ConstantExpr>(C2)) { 1158 // If C2 is a constant expr and C1 isn't, flop them around and fold the 1159 // other way if possible. 1160 if (Instruction::isCommutative(Opcode)) 1161 return ConstantFoldBinaryInstruction(Opcode, C2, C1); 1162 } 1163 1164 // i1 can be simplified in many cases. 1165 if (C1->getType()->isIntegerTy(1)) { 1166 switch (Opcode) { 1167 case Instruction::Add: 1168 case Instruction::Sub: 1169 return ConstantExpr::getXor(C1, C2); 1170 case Instruction::Mul: 1171 return ConstantExpr::getAnd(C1, C2); 1172 case Instruction::Shl: 1173 case Instruction::LShr: 1174 case Instruction::AShr: 1175 // We can assume that C2 == 0. If it were one the result would be 1176 // undefined because the shift value is as large as the bitwidth. 1177 return C1; 1178 case Instruction::SDiv: 1179 case Instruction::UDiv: 1180 // We can assume that C2 == 1. If it were zero the result would be 1181 // undefined through division by zero. 1182 return C1; 1183 case Instruction::URem: 1184 case Instruction::SRem: 1185 // We can assume that C2 == 1. If it were zero the result would be 1186 // undefined through division by zero. 1187 return ConstantInt::getFalse(C1->getContext()); 1188 default: 1189 break; 1190 } 1191 } 1192 1193 // We don't know how to fold this. 1194 return 0; 1195 } 1196 1197 /// isZeroSizedType - This type is zero sized if its an array or structure of 1198 /// zero sized types. The only leaf zero sized type is an empty structure. 1199 static bool isMaybeZeroSizedType(Type *Ty) { 1200 if (StructType *STy = dyn_cast<StructType>(Ty)) { 1201 if (STy->isOpaque()) return true; // Can't say. 1202 1203 // If all of elements have zero size, this does too. 1204 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 1205 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 1206 return true; 1207 1208 } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 1209 return isMaybeZeroSizedType(ATy->getElementType()); 1210 } 1211 return false; 1212 } 1213 1214 /// IdxCompare - Compare the two constants as though they were getelementptr 1215 /// indices. This allows coersion of the types to be the same thing. 1216 /// 1217 /// If the two constants are the "same" (after coersion), return 0. If the 1218 /// first is less than the second, return -1, if the second is less than the 1219 /// first, return 1. If the constants are not integral, return -2. 1220 /// 1221 static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) { 1222 if (C1 == C2) return 0; 1223 1224 // Ok, we found a different index. If they are not ConstantInt, we can't do 1225 // anything with them. 1226 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 1227 return -2; // don't know! 1228 1229 // Ok, we have two differing integer indices. Sign extend them to be the same 1230 // type. Long is always big enough, so we use it. 1231 if (!C1->getType()->isIntegerTy(64)) 1232 C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext())); 1233 1234 if (!C2->getType()->isIntegerTy(64)) 1235 C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext())); 1236 1237 if (C1 == C2) return 0; // They are equal 1238 1239 // If the type being indexed over is really just a zero sized type, there is 1240 // no pointer difference being made here. 1241 if (isMaybeZeroSizedType(ElTy)) 1242 return -2; // dunno. 1243 1244 // If they are really different, now that they are the same type, then we 1245 // found a difference! 1246 if (cast<ConstantInt>(C1)->getSExtValue() < 1247 cast<ConstantInt>(C2)->getSExtValue()) 1248 return -1; 1249 else 1250 return 1; 1251 } 1252 1253 /// evaluateFCmpRelation - This function determines if there is anything we can 1254 /// decide about the two constants provided. This doesn't need to handle simple 1255 /// things like ConstantFP comparisons, but should instead handle ConstantExprs. 1256 /// If we can determine that the two constants have a particular relation to 1257 /// each other, we should return the corresponding FCmpInst predicate, 1258 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 1259 /// ConstantFoldCompareInstruction. 1260 /// 1261 /// To simplify this code we canonicalize the relation so that the first 1262 /// operand is always the most "complex" of the two. We consider ConstantFP 1263 /// to be the simplest, and ConstantExprs to be the most complex. 1264 static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { 1265 assert(V1->getType() == V2->getType() && 1266 "Cannot compare values of different types!"); 1267 1268 // No compile-time operations on this type yet. 1269 if (V1->getType()->isPPC_FP128Ty()) 1270 return FCmpInst::BAD_FCMP_PREDICATE; 1271 1272 // Handle degenerate case quickly 1273 if (V1 == V2) return FCmpInst::FCMP_OEQ; 1274 1275 if (!isa<ConstantExpr>(V1)) { 1276 if (!isa<ConstantExpr>(V2)) { 1277 // We distilled thisUse the standard constant folder for a few cases 1278 ConstantInt *R = 0; 1279 R = dyn_cast<ConstantInt>( 1280 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); 1281 if (R && !R->isZero()) 1282 return FCmpInst::FCMP_OEQ; 1283 R = dyn_cast<ConstantInt>( 1284 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); 1285 if (R && !R->isZero()) 1286 return FCmpInst::FCMP_OLT; 1287 R = dyn_cast<ConstantInt>( 1288 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); 1289 if (R && !R->isZero()) 1290 return FCmpInst::FCMP_OGT; 1291 1292 // Nothing more we can do 1293 return FCmpInst::BAD_FCMP_PREDICATE; 1294 } 1295 1296 // If the first operand is simple and second is ConstantExpr, swap operands. 1297 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); 1298 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 1299 return FCmpInst::getSwappedPredicate(SwappedRelation); 1300 } else { 1301 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1302 // constantexpr or a simple constant. 1303 ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1304 switch (CE1->getOpcode()) { 1305 case Instruction::FPTrunc: 1306 case Instruction::FPExt: 1307 case Instruction::UIToFP: 1308 case Instruction::SIToFP: 1309 // We might be able to do something with these but we don't right now. 1310 break; 1311 default: 1312 break; 1313 } 1314 } 1315 // There are MANY other foldings that we could perform here. They will 1316 // probably be added on demand, as they seem needed. 1317 return FCmpInst::BAD_FCMP_PREDICATE; 1318 } 1319 1320 /// evaluateICmpRelation - This function determines if there is anything we can 1321 /// decide about the two constants provided. This doesn't need to handle simple 1322 /// things like integer comparisons, but should instead handle ConstantExprs 1323 /// and GlobalValues. If we can determine that the two constants have a 1324 /// particular relation to each other, we should return the corresponding ICmp 1325 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 1326 /// 1327 /// To simplify this code we canonicalize the relation so that the first 1328 /// operand is always the most "complex" of the two. We consider simple 1329 /// constants (like ConstantInt) to be the simplest, followed by 1330 /// GlobalValues, followed by ConstantExpr's (the most complex). 1331 /// 1332 static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, 1333 bool isSigned) { 1334 assert(V1->getType() == V2->getType() && 1335 "Cannot compare different types of values!"); 1336 if (V1 == V2) return ICmpInst::ICMP_EQ; 1337 1338 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && 1339 !isa<BlockAddress>(V1)) { 1340 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && 1341 !isa<BlockAddress>(V2)) { 1342 // We distilled this down to a simple case, use the standard constant 1343 // folder. 1344 ConstantInt *R = 0; 1345 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 1346 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1347 if (R && !R->isZero()) 1348 return pred; 1349 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1350 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1351 if (R && !R->isZero()) 1352 return pred; 1353 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1354 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1355 if (R && !R->isZero()) 1356 return pred; 1357 1358 // If we couldn't figure it out, bail. 1359 return ICmpInst::BAD_ICMP_PREDICATE; 1360 } 1361 1362 // If the first operand is simple, swap operands. 1363 ICmpInst::Predicate SwappedRelation = 1364 evaluateICmpRelation(V2, V1, isSigned); 1365 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1366 return ICmpInst::getSwappedPredicate(SwappedRelation); 1367 1368 } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { 1369 if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1370 ICmpInst::Predicate SwappedRelation = 1371 evaluateICmpRelation(V2, V1, isSigned); 1372 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1373 return ICmpInst::getSwappedPredicate(SwappedRelation); 1374 return ICmpInst::BAD_ICMP_PREDICATE; 1375 } 1376 1377 // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1378 // constant (which, since the types must match, means that it's a 1379 // ConstantPointerNull). 1380 if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1381 // Don't try to decide equality of aliases. 1382 if (!isa<GlobalAlias>(GV) && !isa<GlobalAlias>(GV2)) 1383 if (!GV->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage()) 1384 return ICmpInst::ICMP_NE; 1385 } else if (isa<BlockAddress>(V2)) { 1386 return ICmpInst::ICMP_NE; // Globals never equal labels. 1387 } else { 1388 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 1389 // GlobalVals can never be null unless they have external weak linkage. 1390 // We don't try to evaluate aliases here. 1391 if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV)) 1392 return ICmpInst::ICMP_NE; 1393 } 1394 } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { 1395 if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1396 ICmpInst::Predicate SwappedRelation = 1397 evaluateICmpRelation(V2, V1, isSigned); 1398 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1399 return ICmpInst::getSwappedPredicate(SwappedRelation); 1400 return ICmpInst::BAD_ICMP_PREDICATE; 1401 } 1402 1403 // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1404 // constant (which, since the types must match, means that it is a 1405 // ConstantPointerNull). 1406 if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { 1407 // Block address in another function can't equal this one, but block 1408 // addresses in the current function might be the same if blocks are 1409 // empty. 1410 if (BA2->getFunction() != BA->getFunction()) 1411 return ICmpInst::ICMP_NE; 1412 } else { 1413 // Block addresses aren't null, don't equal the address of globals. 1414 assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && 1415 "Canonicalization guarantee!"); 1416 return ICmpInst::ICMP_NE; 1417 } 1418 } else { 1419 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1420 // constantexpr, a global, block address, or a simple constant. 1421 ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1422 Constant *CE1Op0 = CE1->getOperand(0); 1423 1424 switch (CE1->getOpcode()) { 1425 case Instruction::Trunc: 1426 case Instruction::FPTrunc: 1427 case Instruction::FPExt: 1428 case Instruction::FPToUI: 1429 case Instruction::FPToSI: 1430 break; // We can't evaluate floating point casts or truncations. 1431 1432 case Instruction::UIToFP: 1433 case Instruction::SIToFP: 1434 case Instruction::BitCast: 1435 case Instruction::ZExt: 1436 case Instruction::SExt: 1437 // If the cast is not actually changing bits, and the second operand is a 1438 // null pointer, do the comparison with the pre-casted value. 1439 if (V2->isNullValue() && 1440 (CE1->getType()->isPointerTy() || CE1->getType()->isIntegerTy())) { 1441 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 1442 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 1443 return evaluateICmpRelation(CE1Op0, 1444 Constant::getNullValue(CE1Op0->getType()), 1445 isSigned); 1446 } 1447 break; 1448 1449 case Instruction::GetElementPtr: 1450 // Ok, since this is a getelementptr, we know that the constant has a 1451 // pointer type. Check the various cases. 1452 if (isa<ConstantPointerNull>(V2)) { 1453 // If we are comparing a GEP to a null pointer, check to see if the base 1454 // of the GEP equals the null pointer. 1455 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1456 if (GV->hasExternalWeakLinkage()) 1457 // Weak linkage GVals could be zero or not. We're comparing that 1458 // to null pointer so its greater-or-equal 1459 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1460 else 1461 // If its not weak linkage, the GVal must have a non-zero address 1462 // so the result is greater-than 1463 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1464 } else if (isa<ConstantPointerNull>(CE1Op0)) { 1465 // If we are indexing from a null pointer, check to see if we have any 1466 // non-zero indices. 1467 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1468 if (!CE1->getOperand(i)->isNullValue()) 1469 // Offsetting from null, must not be equal. 1470 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1471 // Only zero indexes from null, must still be zero. 1472 return ICmpInst::ICMP_EQ; 1473 } 1474 // Otherwise, we can't really say if the first operand is null or not. 1475 } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1476 if (isa<ConstantPointerNull>(CE1Op0)) { 1477 if (GV2->hasExternalWeakLinkage()) 1478 // Weak linkage GVals could be zero or not. We're comparing it to 1479 // a null pointer, so its less-or-equal 1480 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1481 else 1482 // If its not weak linkage, the GVal must have a non-zero address 1483 // so the result is less-than 1484 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1485 } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1486 if (GV == GV2) { 1487 // If this is a getelementptr of the same global, then it must be 1488 // different. Because the types must match, the getelementptr could 1489 // only have at most one index, and because we fold getelementptr's 1490 // with a single zero index, it must be nonzero. 1491 assert(CE1->getNumOperands() == 2 && 1492 !CE1->getOperand(1)->isNullValue() && 1493 "Surprising getelementptr!"); 1494 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1495 } else { 1496 // If they are different globals, we don't know what the value is, 1497 // but they can't be equal. 1498 return ICmpInst::ICMP_NE; 1499 } 1500 } 1501 } else { 1502 ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1503 Constant *CE2Op0 = CE2->getOperand(0); 1504 1505 // There are MANY other foldings that we could perform here. They will 1506 // probably be added on demand, as they seem needed. 1507 switch (CE2->getOpcode()) { 1508 default: break; 1509 case Instruction::GetElementPtr: 1510 // By far the most common case to handle is when the base pointers are 1511 // obviously to the same or different globals. 1512 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1513 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal 1514 return ICmpInst::ICMP_NE; 1515 // Ok, we know that both getelementptr instructions are based on the 1516 // same global. From this, we can precisely determine the relative 1517 // ordering of the resultant pointers. 1518 unsigned i = 1; 1519 1520 // The logic below assumes that the result of the comparison 1521 // can be determined by finding the first index that differs. 1522 // This doesn't work if there is over-indexing in any 1523 // subsequent indices, so check for that case first. 1524 if (!CE1->isGEPWithNoNotionalOverIndexing() || 1525 !CE2->isGEPWithNoNotionalOverIndexing()) 1526 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1527 1528 // Compare all of the operands the GEP's have in common. 1529 gep_type_iterator GTI = gep_type_begin(CE1); 1530 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1531 ++i, ++GTI) 1532 switch (IdxCompare(CE1->getOperand(i), 1533 CE2->getOperand(i), GTI.getIndexedType())) { 1534 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1535 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1536 case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1537 } 1538 1539 // Ok, we ran out of things they have in common. If any leftovers 1540 // are non-zero then we have a difference, otherwise we are equal. 1541 for (; i < CE1->getNumOperands(); ++i) 1542 if (!CE1->getOperand(i)->isNullValue()) { 1543 if (isa<ConstantInt>(CE1->getOperand(i))) 1544 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1545 else 1546 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1547 } 1548 1549 for (; i < CE2->getNumOperands(); ++i) 1550 if (!CE2->getOperand(i)->isNullValue()) { 1551 if (isa<ConstantInt>(CE2->getOperand(i))) 1552 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1553 else 1554 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1555 } 1556 return ICmpInst::ICMP_EQ; 1557 } 1558 } 1559 } 1560 default: 1561 break; 1562 } 1563 } 1564 1565 return ICmpInst::BAD_ICMP_PREDICATE; 1566 } 1567 1568 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred, 1569 Constant *C1, Constant *C2) { 1570 Type *ResultTy; 1571 if (VectorType *VT = dyn_cast<VectorType>(C1->getType())) 1572 ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()), 1573 VT->getNumElements()); 1574 else 1575 ResultTy = Type::getInt1Ty(C1->getContext()); 1576 1577 // Fold FCMP_FALSE/FCMP_TRUE unconditionally. 1578 if (pred == FCmpInst::FCMP_FALSE) 1579 return Constant::getNullValue(ResultTy); 1580 1581 if (pred == FCmpInst::FCMP_TRUE) 1582 return Constant::getAllOnesValue(ResultTy); 1583 1584 // Handle some degenerate cases first 1585 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 1586 // For EQ and NE, we can always pick a value for the undef to make the 1587 // predicate pass or fail, so we can return undef. 1588 // Also, if both operands are undef, we can return undef. 1589 if (ICmpInst::isEquality(ICmpInst::Predicate(pred)) || 1590 (isa<UndefValue>(C1) && isa<UndefValue>(C2))) 1591 return UndefValue::get(ResultTy); 1592 // Otherwise, pick the same value as the non-undef operand, and fold 1593 // it to true or false. 1594 return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred)); 1595 } 1596 1597 // No compile-time operations on this type yet. 1598 if (C1->getType()->isPPC_FP128Ty()) 1599 return 0; 1600 1601 // icmp eq/ne(null,GV) -> false/true 1602 if (C1->isNullValue()) { 1603 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1604 // Don't try to evaluate aliases. External weak GV can be null. 1605 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1606 if (pred == ICmpInst::ICMP_EQ) 1607 return ConstantInt::getFalse(C1->getContext()); 1608 else if (pred == ICmpInst::ICMP_NE) 1609 return ConstantInt::getTrue(C1->getContext()); 1610 } 1611 // icmp eq/ne(GV,null) -> false/true 1612 } else if (C2->isNullValue()) { 1613 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1614 // Don't try to evaluate aliases. External weak GV can be null. 1615 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1616 if (pred == ICmpInst::ICMP_EQ) 1617 return ConstantInt::getFalse(C1->getContext()); 1618 else if (pred == ICmpInst::ICMP_NE) 1619 return ConstantInt::getTrue(C1->getContext()); 1620 } 1621 } 1622 1623 // If the comparison is a comparison between two i1's, simplify it. 1624 if (C1->getType()->isIntegerTy(1)) { 1625 switch(pred) { 1626 case ICmpInst::ICMP_EQ: 1627 if (isa<ConstantInt>(C2)) 1628 return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); 1629 return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); 1630 case ICmpInst::ICMP_NE: 1631 return ConstantExpr::getXor(C1, C2); 1632 default: 1633 break; 1634 } 1635 } 1636 1637 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1638 APInt V1 = cast<ConstantInt>(C1)->getValue(); 1639 APInt V2 = cast<ConstantInt>(C2)->getValue(); 1640 switch (pred) { 1641 default: llvm_unreachable("Invalid ICmp Predicate"); 1642 case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2); 1643 case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2); 1644 case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2)); 1645 case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2)); 1646 case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2)); 1647 case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2)); 1648 case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2)); 1649 case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2)); 1650 case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2)); 1651 case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2)); 1652 } 1653 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1654 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1655 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1656 APFloat::cmpResult R = C1V.compare(C2V); 1657 switch (pred) { 1658 default: llvm_unreachable("Invalid FCmp Predicate"); 1659 case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy); 1660 case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy); 1661 case FCmpInst::FCMP_UNO: 1662 return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered); 1663 case FCmpInst::FCMP_ORD: 1664 return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered); 1665 case FCmpInst::FCMP_UEQ: 1666 return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1667 R==APFloat::cmpEqual); 1668 case FCmpInst::FCMP_OEQ: 1669 return ConstantInt::get(ResultTy, R==APFloat::cmpEqual); 1670 case FCmpInst::FCMP_UNE: 1671 return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual); 1672 case FCmpInst::FCMP_ONE: 1673 return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1674 R==APFloat::cmpGreaterThan); 1675 case FCmpInst::FCMP_ULT: 1676 return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1677 R==APFloat::cmpLessThan); 1678 case FCmpInst::FCMP_OLT: 1679 return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan); 1680 case FCmpInst::FCMP_UGT: 1681 return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1682 R==APFloat::cmpGreaterThan); 1683 case FCmpInst::FCMP_OGT: 1684 return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan); 1685 case FCmpInst::FCMP_ULE: 1686 return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan); 1687 case FCmpInst::FCMP_OLE: 1688 return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1689 R==APFloat::cmpEqual); 1690 case FCmpInst::FCMP_UGE: 1691 return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan); 1692 case FCmpInst::FCMP_OGE: 1693 return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan || 1694 R==APFloat::cmpEqual); 1695 } 1696 } else if (C1->getType()->isVectorTy()) { 1697 // If we can constant fold the comparison of each element, constant fold 1698 // the whole vector comparison. 1699 SmallVector<Constant*, 4> ResElts; 1700 // Compare the elements, producing an i1 result or constant expr. 1701 for (unsigned i = 0, e = C1->getType()->getVectorNumElements(); i != e;++i){ 1702 Constant *C1E = C1->getAggregateElement(i); 1703 Constant *C2E = C2->getAggregateElement(i); 1704 if (C1E == 0 || C2E == 0) break; 1705 1706 ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E)); 1707 } 1708 1709 if (ResElts.size() == C1->getType()->getVectorNumElements()) 1710 return ConstantVector::get(ResElts); 1711 } 1712 1713 if (C1->getType()->isFloatingPointTy()) { 1714 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1715 switch (evaluateFCmpRelation(C1, C2)) { 1716 default: llvm_unreachable("Unknown relation!"); 1717 case FCmpInst::FCMP_UNO: 1718 case FCmpInst::FCMP_ORD: 1719 case FCmpInst::FCMP_UEQ: 1720 case FCmpInst::FCMP_UNE: 1721 case FCmpInst::FCMP_ULT: 1722 case FCmpInst::FCMP_UGT: 1723 case FCmpInst::FCMP_ULE: 1724 case FCmpInst::FCMP_UGE: 1725 case FCmpInst::FCMP_TRUE: 1726 case FCmpInst::FCMP_FALSE: 1727 case FCmpInst::BAD_FCMP_PREDICATE: 1728 break; // Couldn't determine anything about these constants. 1729 case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1730 Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1731 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1732 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1733 break; 1734 case FCmpInst::FCMP_OLT: // We know that C1 < C2 1735 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1736 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1737 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1738 break; 1739 case FCmpInst::FCMP_OGT: // We know that C1 > C2 1740 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1741 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1742 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1743 break; 1744 case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1745 // We can only partially decide this relation. 1746 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1747 Result = 0; 1748 else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1749 Result = 1; 1750 break; 1751 case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1752 // We can only partially decide this relation. 1753 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1754 Result = 0; 1755 else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1756 Result = 1; 1757 break; 1758 case FCmpInst::FCMP_ONE: // We know that C1 != C2 1759 // We can only partially decide this relation. 1760 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1761 Result = 0; 1762 else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1763 Result = 1; 1764 break; 1765 } 1766 1767 // If we evaluated the result, return it now. 1768 if (Result != -1) 1769 return ConstantInt::get(ResultTy, Result); 1770 1771 } else { 1772 // Evaluate the relation between the two constants, per the predicate. 1773 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1774 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { 1775 default: llvm_unreachable("Unknown relational!"); 1776 case ICmpInst::BAD_ICMP_PREDICATE: 1777 break; // Couldn't determine anything about these constants. 1778 case ICmpInst::ICMP_EQ: // We know the constants are equal! 1779 // If we know the constants are equal, we can decide the result of this 1780 // computation precisely. 1781 Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); 1782 break; 1783 case ICmpInst::ICMP_ULT: 1784 switch (pred) { 1785 case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: 1786 Result = 1; break; 1787 case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: 1788 Result = 0; break; 1789 } 1790 break; 1791 case ICmpInst::ICMP_SLT: 1792 switch (pred) { 1793 case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: 1794 Result = 1; break; 1795 case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: 1796 Result = 0; break; 1797 } 1798 break; 1799 case ICmpInst::ICMP_UGT: 1800 switch (pred) { 1801 case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: 1802 Result = 1; break; 1803 case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: 1804 Result = 0; break; 1805 } 1806 break; 1807 case ICmpInst::ICMP_SGT: 1808 switch (pred) { 1809 case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: 1810 Result = 1; break; 1811 case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: 1812 Result = 0; break; 1813 } 1814 break; 1815 case ICmpInst::ICMP_ULE: 1816 if (pred == ICmpInst::ICMP_UGT) Result = 0; 1817 if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; 1818 break; 1819 case ICmpInst::ICMP_SLE: 1820 if (pred == ICmpInst::ICMP_SGT) Result = 0; 1821 if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; 1822 break; 1823 case ICmpInst::ICMP_UGE: 1824 if (pred == ICmpInst::ICMP_ULT) Result = 0; 1825 if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; 1826 break; 1827 case ICmpInst::ICMP_SGE: 1828 if (pred == ICmpInst::ICMP_SLT) Result = 0; 1829 if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; 1830 break; 1831 case ICmpInst::ICMP_NE: 1832 if (pred == ICmpInst::ICMP_EQ) Result = 0; 1833 if (pred == ICmpInst::ICMP_NE) Result = 1; 1834 break; 1835 } 1836 1837 // If we evaluated the result, return it now. 1838 if (Result != -1) 1839 return ConstantInt::get(ResultTy, Result); 1840 1841 // If the right hand side is a bitcast, try using its inverse to simplify 1842 // it by moving it to the left hand side. We can't do this if it would turn 1843 // a vector compare into a scalar compare or visa versa. 1844 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { 1845 Constant *CE2Op0 = CE2->getOperand(0); 1846 if (CE2->getOpcode() == Instruction::BitCast && 1847 CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) { 1848 Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); 1849 return ConstantExpr::getICmp(pred, Inverse, CE2Op0); 1850 } 1851 } 1852 1853 // If the left hand side is an extension, try eliminating it. 1854 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1855 if ((CE1->getOpcode() == Instruction::SExt && ICmpInst::isSigned(pred)) || 1856 (CE1->getOpcode() == Instruction::ZExt && !ICmpInst::isSigned(pred))){ 1857 Constant *CE1Op0 = CE1->getOperand(0); 1858 Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); 1859 if (CE1Inverse == CE1Op0) { 1860 // Check whether we can safely truncate the right hand side. 1861 Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); 1862 if (ConstantExpr::getZExt(C2Inverse, C2->getType()) == C2) { 1863 return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); 1864 } 1865 } 1866 } 1867 } 1868 1869 if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || 1870 (C1->isNullValue() && !C2->isNullValue())) { 1871 // If C2 is a constant expr and C1 isn't, flip them around and fold the 1872 // other way if possible. 1873 // Also, if C1 is null and C2 isn't, flip them around. 1874 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1875 return ConstantExpr::getICmp(pred, C2, C1); 1876 } 1877 } 1878 return 0; 1879 } 1880 1881 /// isInBoundsIndices - Test whether the given sequence of *normalized* indices 1882 /// is "inbounds". 1883 template<typename IndexTy> 1884 static bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) { 1885 // No indices means nothing that could be out of bounds. 1886 if (Idxs.empty()) return true; 1887 1888 // If the first index is zero, it's in bounds. 1889 if (cast<Constant>(Idxs[0])->isNullValue()) return true; 1890 1891 // If the first index is one and all the rest are zero, it's in bounds, 1892 // by the one-past-the-end rule. 1893 if (!cast<ConstantInt>(Idxs[0])->isOne()) 1894 return false; 1895 for (unsigned i = 1, e = Idxs.size(); i != e; ++i) 1896 if (!cast<Constant>(Idxs[i])->isNullValue()) 1897 return false; 1898 return true; 1899 } 1900 1901 template<typename IndexTy> 1902 static Constant *ConstantFoldGetElementPtrImpl(Constant *C, 1903 bool inBounds, 1904 ArrayRef<IndexTy> Idxs) { 1905 if (Idxs.empty()) return C; 1906 Constant *Idx0 = cast<Constant>(Idxs[0]); 1907 if ((Idxs.size() == 1 && Idx0->isNullValue())) 1908 return C; 1909 1910 if (isa<UndefValue>(C)) { 1911 PointerType *Ptr = cast<PointerType>(C->getType()); 1912 Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); 1913 assert(Ty != 0 && "Invalid indices for GEP!"); 1914 return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 1915 } 1916 1917 if (C->isNullValue()) { 1918 bool isNull = true; 1919 for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 1920 if (!cast<Constant>(Idxs[i])->isNullValue()) { 1921 isNull = false; 1922 break; 1923 } 1924 if (isNull) { 1925 PointerType *Ptr = cast<PointerType>(C->getType()); 1926 Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); 1927 assert(Ty != 0 && "Invalid indices for GEP!"); 1928 return ConstantPointerNull::get(PointerType::get(Ty, 1929 Ptr->getAddressSpace())); 1930 } 1931 } 1932 1933 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { 1934 // Combine Indices - If the source pointer to this getelementptr instruction 1935 // is a getelementptr instruction, combine the indices of the two 1936 // getelementptr instructions into a single instruction. 1937 // 1938 if (CE->getOpcode() == Instruction::GetElementPtr) { 1939 Type *LastTy = 0; 1940 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 1941 I != E; ++I) 1942 LastTy = *I; 1943 1944 if ((LastTy && isa<SequentialType>(LastTy)) || Idx0->isNullValue()) { 1945 SmallVector<Value*, 16> NewIndices; 1946 NewIndices.reserve(Idxs.size() + CE->getNumOperands()); 1947 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) 1948 NewIndices.push_back(CE->getOperand(i)); 1949 1950 // Add the last index of the source with the first index of the new GEP. 1951 // Make sure to handle the case when they are actually different types. 1952 Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 1953 // Otherwise it must be an array. 1954 if (!Idx0->isNullValue()) { 1955 Type *IdxTy = Combined->getType(); 1956 if (IdxTy != Idx0->getType()) { 1957 Type *Int64Ty = Type::getInt64Ty(IdxTy->getContext()); 1958 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Int64Ty); 1959 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, Int64Ty); 1960 Combined = ConstantExpr::get(Instruction::Add, C1, C2); 1961 } else { 1962 Combined = 1963 ConstantExpr::get(Instruction::Add, Idx0, Combined); 1964 } 1965 } 1966 1967 NewIndices.push_back(Combined); 1968 NewIndices.append(Idxs.begin() + 1, Idxs.end()); 1969 return 1970 ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices, 1971 inBounds && 1972 cast<GEPOperator>(CE)->isInBounds()); 1973 } 1974 } 1975 1976 // Implement folding of: 1977 // i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*), 1978 // i64 0, i64 0) 1979 // To: i32* getelementptr ([3 x i32]* %X, i64 0, i64 0) 1980 // 1981 if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) { 1982 if (PointerType *SPT = 1983 dyn_cast<PointerType>(CE->getOperand(0)->getType())) 1984 if (ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) 1985 if (ArrayType *CAT = 1986 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) 1987 if (CAT->getElementType() == SAT->getElementType()) 1988 return 1989 ConstantExpr::getGetElementPtr((Constant*)CE->getOperand(0), 1990 Idxs, inBounds); 1991 } 1992 } 1993 1994 // Check to see if any array indices are not within the corresponding 1995 // notional array bounds. If so, try to determine if they can be factored 1996 // out into preceding dimensions. 1997 bool Unknown = false; 1998 SmallVector<Constant *, 8> NewIdxs; 1999 Type *Ty = C->getType(); 2000 Type *Prev = 0; 2001 for (unsigned i = 0, e = Idxs.size(); i != e; 2002 Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { 2003 if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { 2004 if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) 2005 if (ATy->getNumElements() <= INT64_MAX && 2006 ATy->getNumElements() != 0 && 2007 CI->getSExtValue() >= (int64_t)ATy->getNumElements()) { 2008 if (isa<SequentialType>(Prev)) { 2009 // It's out of range, but we can factor it into the prior 2010 // dimension. 2011 NewIdxs.resize(Idxs.size()); 2012 ConstantInt *Factor = ConstantInt::get(CI->getType(), 2013 ATy->getNumElements()); 2014 NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); 2015 2016 Constant *PrevIdx = cast<Constant>(Idxs[i-1]); 2017 Constant *Div = ConstantExpr::getSDiv(CI, Factor); 2018 2019 // Before adding, extend both operands to i64 to avoid 2020 // overflow trouble. 2021 if (!PrevIdx->getType()->isIntegerTy(64)) 2022 PrevIdx = ConstantExpr::getSExt(PrevIdx, 2023 Type::getInt64Ty(Div->getContext())); 2024 if (!Div->getType()->isIntegerTy(64)) 2025 Div = ConstantExpr::getSExt(Div, 2026 Type::getInt64Ty(Div->getContext())); 2027 2028 NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); 2029 } else { 2030 // It's out of range, but the prior dimension is a struct 2031 // so we can't do anything about it. 2032 Unknown = true; 2033 } 2034 } 2035 } else { 2036 // We don't know if it's in range or not. 2037 Unknown = true; 2038 } 2039 } 2040 2041 // If we did any factoring, start over with the adjusted indices. 2042 if (!NewIdxs.empty()) { 2043 for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 2044 if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]); 2045 return ConstantExpr::getGetElementPtr(C, NewIdxs, inBounds); 2046 } 2047 2048 // If all indices are known integers and normalized, we can do a simple 2049 // check for the "inbounds" property. 2050 if (!Unknown && !inBounds && 2051 isa<GlobalVariable>(C) && isInBoundsIndices(Idxs)) 2052 return ConstantExpr::getInBoundsGetElementPtr(C, Idxs); 2053 2054 return 0; 2055 } 2056 2057 Constant *llvm::ConstantFoldGetElementPtr(Constant *C, 2058 bool inBounds, 2059 ArrayRef<Constant *> Idxs) { 2060 return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); 2061 } 2062 2063 Constant *llvm::ConstantFoldGetElementPtr(Constant *C, 2064 bool inBounds, 2065 ArrayRef<Value *> Idxs) { 2066 return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); 2067 } 2068