ScalarReplAggregates.cpp revision 6860f6a01ccc71d7cad61de506e0cf8ecb8ca146
1//===- ScalarReplAggregates.cpp - Scalar Replacement of Aggregates --------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This transformation implements the well known scalar replacement of 11// aggregates transformation. This xform breaks up alloca instructions of 12// aggregate type (structure or array) into individual alloca instructions for 13// each member (if possible). Then, if possible, it transforms the individual 14// alloca instructions into nice clean scalar SSA form. 15// 16// This combines a simple SRoA algorithm with the Mem2Reg algorithm because 17// often interact, especially for C++ programs. As such, iterating between 18// SRoA, then Mem2Reg until we run out of things to promote works well. 19// 20//===----------------------------------------------------------------------===// 21 22#include "llvm/Transforms/Scalar.h" 23#include "llvm/Constants.h" 24#include "llvm/DerivedTypes.h" 25#include "llvm/Function.h" 26#include "llvm/Pass.h" 27#include "llvm/Instructions.h" 28#include "llvm/Analysis/Dominators.h" 29#include "llvm/Target/TargetData.h" 30#include "llvm/Transforms/Utils/PromoteMemToReg.h" 31#include "llvm/Support/GetElementPtrTypeIterator.h" 32#include "llvm/Support/MathExtras.h" 33#include "llvm/Support/Debug.h" 34#include "llvm/ADT/Statistic.h" 35#include "llvm/ADT/StringExtras.h" 36using namespace llvm; 37 38namespace { 39 Statistic<> NumReplaced("scalarrepl", "Number of allocas broken up"); 40 Statistic<> NumPromoted("scalarrepl", "Number of allocas promoted"); 41 Statistic<> NumConverted("scalarrepl", 42 "Number of aggregates converted to scalar"); 43 44 struct SROA : public FunctionPass { 45 bool runOnFunction(Function &F); 46 47 bool performScalarRepl(Function &F); 48 bool performPromotion(Function &F); 49 50 // getAnalysisUsage - This pass does not require any passes, but we know it 51 // will not alter the CFG, so say so. 52 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 53 AU.addRequired<DominatorTree>(); 54 AU.addRequired<DominanceFrontier>(); 55 AU.addRequired<TargetData>(); 56 AU.setPreservesCFG(); 57 } 58 59 private: 60 int isSafeElementUse(Value *Ptr); 61 int isSafeUseOfAllocation(Instruction *User); 62 int isSafeAllocaToScalarRepl(AllocationInst *AI); 63 void CanonicalizeAllocaUsers(AllocationInst *AI); 64 AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base); 65 66 const Type *CanConvertToScalar(Value *V, bool &IsNotTrivial); 67 void ConvertToScalar(AllocationInst *AI, const Type *Ty); 68 void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset); 69 }; 70 71 RegisterOpt<SROA> X("scalarrepl", "Scalar Replacement of Aggregates"); 72} 73 74// Public interface to the ScalarReplAggregates pass 75FunctionPass *llvm::createScalarReplAggregatesPass() { return new SROA(); } 76 77 78bool SROA::runOnFunction(Function &F) { 79 bool Changed = performPromotion(F); 80 while (1) { 81 bool LocalChange = performScalarRepl(F); 82 if (!LocalChange) break; // No need to repromote if no scalarrepl 83 Changed = true; 84 LocalChange = performPromotion(F); 85 if (!LocalChange) break; // No need to re-scalarrepl if no promotion 86 } 87 88 return Changed; 89} 90 91 92bool SROA::performPromotion(Function &F) { 93 std::vector<AllocaInst*> Allocas; 94 const TargetData &TD = getAnalysis<TargetData>(); 95 DominatorTree &DT = getAnalysis<DominatorTree>(); 96 DominanceFrontier &DF = getAnalysis<DominanceFrontier>(); 97 98 BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function 99 100 bool Changed = false; 101 102 while (1) { 103 Allocas.clear(); 104 105 // Find allocas that are safe to promote, by looking at all instructions in 106 // the entry node 107 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I) 108 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca? 109 if (isAllocaPromotable(AI, TD)) 110 Allocas.push_back(AI); 111 112 if (Allocas.empty()) break; 113 114 PromoteMemToReg(Allocas, DT, DF, TD); 115 NumPromoted += Allocas.size(); 116 Changed = true; 117 } 118 119 return Changed; 120} 121 122// performScalarRepl - This algorithm is a simple worklist driven algorithm, 123// which runs on all of the malloc/alloca instructions in the function, removing 124// them if they are only used by getelementptr instructions. 125// 126bool SROA::performScalarRepl(Function &F) { 127 std::vector<AllocationInst*> WorkList; 128 129 // Scan the entry basic block, adding any alloca's and mallocs to the worklist 130 BasicBlock &BB = F.getEntryBlock(); 131 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 132 if (AllocationInst *A = dyn_cast<AllocationInst>(I)) 133 WorkList.push_back(A); 134 135 // Process the worklist 136 bool Changed = false; 137 while (!WorkList.empty()) { 138 AllocationInst *AI = WorkList.back(); 139 WorkList.pop_back(); 140 141 // If we can turn this aggregate value (potentially with casts) into a 142 // simple scalar value that can be mem2reg'd into a register value. 143 bool IsNotTrivial = false; 144 if (const Type *ActualType = CanConvertToScalar(AI, IsNotTrivial)) 145 if (IsNotTrivial) { 146 ConvertToScalar(AI, ActualType); 147 Changed = true; 148 continue; 149 } 150 151 // We cannot transform the allocation instruction if it is an array 152 // allocation (allocations OF arrays are ok though), and an allocation of a 153 // scalar value cannot be decomposed at all. 154 // 155 if (AI->isArrayAllocation() || 156 (!isa<StructType>(AI->getAllocatedType()) && 157 !isa<ArrayType>(AI->getAllocatedType()))) continue; 158 159 // Check that all of the users of the allocation are capable of being 160 // transformed. 161 switch (isSafeAllocaToScalarRepl(AI)) { 162 default: assert(0 && "Unexpected value!"); 163 case 0: // Not safe to scalar replace. 164 continue; 165 case 1: // Safe, but requires cleanup/canonicalizations first 166 CanonicalizeAllocaUsers(AI); 167 case 3: // Safe to scalar replace. 168 break; 169 } 170 171 DEBUG(std::cerr << "Found inst to xform: " << *AI); 172 Changed = true; 173 174 std::vector<AllocaInst*> ElementAllocas; 175 if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) { 176 ElementAllocas.reserve(ST->getNumContainedTypes()); 177 for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) { 178 AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0, 179 AI->getAlignment(), 180 AI->getName() + "." + utostr(i), AI); 181 ElementAllocas.push_back(NA); 182 WorkList.push_back(NA); // Add to worklist for recursive processing 183 } 184 } else { 185 const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType()); 186 ElementAllocas.reserve(AT->getNumElements()); 187 const Type *ElTy = AT->getElementType(); 188 for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) { 189 AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(), 190 AI->getName() + "." + utostr(i), AI); 191 ElementAllocas.push_back(NA); 192 WorkList.push_back(NA); // Add to worklist for recursive processing 193 } 194 } 195 196 // Now that we have created the alloca instructions that we want to use, 197 // expand the getelementptr instructions to use them. 198 // 199 while (!AI->use_empty()) { 200 Instruction *User = cast<Instruction>(AI->use_back()); 201 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User); 202 // We now know that the GEP is of the form: GEP <ptr>, 0, <cst> 203 unsigned Idx = 204 (unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getRawValue(); 205 206 assert(Idx < ElementAllocas.size() && "Index out of range?"); 207 AllocaInst *AllocaToUse = ElementAllocas[Idx]; 208 209 Value *RepValue; 210 if (GEPI->getNumOperands() == 3) { 211 // Do not insert a new getelementptr instruction with zero indices, only 212 // to have it optimized out later. 213 RepValue = AllocaToUse; 214 } else { 215 // We are indexing deeply into the structure, so we still need a 216 // getelement ptr instruction to finish the indexing. This may be 217 // expanded itself once the worklist is rerun. 218 // 219 std::string OldName = GEPI->getName(); // Steal the old name. 220 std::vector<Value*> NewArgs; 221 NewArgs.push_back(Constant::getNullValue(Type::IntTy)); 222 NewArgs.insert(NewArgs.end(), GEPI->op_begin()+3, GEPI->op_end()); 223 GEPI->setName(""); 224 RepValue = new GetElementPtrInst(AllocaToUse, NewArgs, OldName, GEPI); 225 } 226 227 // Move all of the users over to the new GEP. 228 GEPI->replaceAllUsesWith(RepValue); 229 // Delete the old GEP 230 GEPI->eraseFromParent(); 231 } 232 233 // Finally, delete the Alloca instruction 234 AI->getParent()->getInstList().erase(AI); 235 NumReplaced++; 236 } 237 238 return Changed; 239} 240 241 242/// isSafeElementUse - Check to see if this use is an allowed use for a 243/// getelementptr instruction of an array aggregate allocation. 244/// 245int SROA::isSafeElementUse(Value *Ptr) { 246 for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end(); 247 I != E; ++I) { 248 Instruction *User = cast<Instruction>(*I); 249 switch (User->getOpcode()) { 250 case Instruction::Load: break; 251 case Instruction::Store: 252 // Store is ok if storing INTO the pointer, not storing the pointer 253 if (User->getOperand(0) == Ptr) return 0; 254 break; 255 case Instruction::GetElementPtr: { 256 GetElementPtrInst *GEP = cast<GetElementPtrInst>(User); 257 if (GEP->getNumOperands() > 1) { 258 if (!isa<Constant>(GEP->getOperand(1)) || 259 !cast<Constant>(GEP->getOperand(1))->isNullValue()) 260 return 0; // Using pointer arithmetic to navigate the array... 261 } 262 if (!isSafeElementUse(GEP)) return 0; 263 break; 264 } 265 default: 266 DEBUG(std::cerr << " Transformation preventing inst: " << *User); 267 return 0; 268 } 269 } 270 return 3; // All users look ok :) 271} 272 273/// AllUsersAreLoads - Return true if all users of this value are loads. 274static bool AllUsersAreLoads(Value *Ptr) { 275 for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end(); 276 I != E; ++I) 277 if (cast<Instruction>(*I)->getOpcode() != Instruction::Load) 278 return false; 279 return true; 280} 281 282/// isSafeUseOfAllocation - Check to see if this user is an allowed use for an 283/// aggregate allocation. 284/// 285int SROA::isSafeUseOfAllocation(Instruction *User) { 286 if (!isa<GetElementPtrInst>(User)) return 0; 287 288 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User); 289 gep_type_iterator I = gep_type_begin(GEPI), E = gep_type_end(GEPI); 290 291 // The GEP is safe to transform if it is of the form GEP <ptr>, 0, <cst> 292 if (I == E || 293 I.getOperand() != Constant::getNullValue(I.getOperand()->getType())) 294 return 0; 295 296 ++I; 297 if (I == E) return 0; // ran out of GEP indices?? 298 299 // If this is a use of an array allocation, do a bit more checking for sanity. 300 if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) { 301 uint64_t NumElements = AT->getNumElements(); 302 303 if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) { 304 // Check to make sure that index falls within the array. If not, 305 // something funny is going on, so we won't do the optimization. 306 // 307 if (cast<ConstantInt>(GEPI->getOperand(2))->getRawValue() >= NumElements) 308 return 0; 309 310 } else { 311 // If this is an array index and the index is not constant, we cannot 312 // promote... that is unless the array has exactly one or two elements in 313 // it, in which case we CAN promote it, but we have to canonicalize this 314 // out if this is the only problem. 315 if (NumElements == 1 || NumElements == 2) 316 return AllUsersAreLoads(GEPI) ? 1 : 0; // Canonicalization required! 317 return 0; 318 } 319 } 320 321 // If there are any non-simple uses of this getelementptr, make sure to reject 322 // them. 323 return isSafeElementUse(GEPI); 324} 325 326/// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of 327/// an aggregate can be broken down into elements. Return 0 if not, 3 if safe, 328/// or 1 if safe after canonicalization has been performed. 329/// 330int SROA::isSafeAllocaToScalarRepl(AllocationInst *AI) { 331 // Loop over the use list of the alloca. We can only transform it if all of 332 // the users are safe to transform. 333 // 334 int isSafe = 3; 335 for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); 336 I != E; ++I) { 337 isSafe &= isSafeUseOfAllocation(cast<Instruction>(*I)); 338 if (isSafe == 0) { 339 DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: " 340 << **I); 341 return 0; 342 } 343 } 344 // If we require cleanup, isSafe is now 1, otherwise it is 3. 345 return isSafe; 346} 347 348/// CanonicalizeAllocaUsers - If SROA reported that it can promote the specified 349/// allocation, but only if cleaned up, perform the cleanups required. 350void SROA::CanonicalizeAllocaUsers(AllocationInst *AI) { 351 // At this point, we know that the end result will be SROA'd and promoted, so 352 // we can insert ugly code if required so long as sroa+mem2reg will clean it 353 // up. 354 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); 355 UI != E; ) { 356 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(*UI++); 357 gep_type_iterator I = gep_type_begin(GEPI); 358 ++I; 359 360 if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) { 361 uint64_t NumElements = AT->getNumElements(); 362 363 if (!isa<ConstantInt>(I.getOperand())) { 364 if (NumElements == 1) { 365 GEPI->setOperand(2, Constant::getNullValue(Type::IntTy)); 366 } else { 367 assert(NumElements == 2 && "Unhandled case!"); 368 // All users of the GEP must be loads. At each use of the GEP, insert 369 // two loads of the appropriate indexed GEP and select between them. 370 Value *IsOne = BinaryOperator::createSetNE(I.getOperand(), 371 Constant::getNullValue(I.getOperand()->getType()), 372 "isone", GEPI); 373 // Insert the new GEP instructions, which are properly indexed. 374 std::vector<Value*> Indices(GEPI->op_begin()+1, GEPI->op_end()); 375 Indices[1] = Constant::getNullValue(Type::IntTy); 376 Value *ZeroIdx = new GetElementPtrInst(GEPI->getOperand(0), Indices, 377 GEPI->getName()+".0", GEPI); 378 Indices[1] = ConstantInt::get(Type::IntTy, 1); 379 Value *OneIdx = new GetElementPtrInst(GEPI->getOperand(0), Indices, 380 GEPI->getName()+".1", GEPI); 381 // Replace all loads of the variable index GEP with loads from both 382 // indexes and a select. 383 while (!GEPI->use_empty()) { 384 LoadInst *LI = cast<LoadInst>(GEPI->use_back()); 385 Value *Zero = new LoadInst(ZeroIdx, LI->getName()+".0", LI); 386 Value *One = new LoadInst(OneIdx , LI->getName()+".1", LI); 387 Value *R = new SelectInst(IsOne, One, Zero, LI->getName(), LI); 388 LI->replaceAllUsesWith(R); 389 LI->eraseFromParent(); 390 } 391 GEPI->eraseFromParent(); 392 } 393 } 394 } 395 } 396} 397 398/// MergeInType - Add the 'In' type to the accumulated type so far. If the 399/// types are incompatible, return true, otherwise update Accum and return 400/// false. 401static bool MergeInType(const Type *In, const Type *&Accum) { 402 if (!In->isIntegral()) return true; 403 404 // If this is our first type, just use it. 405 if (Accum == Type::VoidTy) { 406 Accum = In; 407 } else { 408 // Otherwise pick whichever type is larger. 409 if (In->getTypeID() > Accum->getTypeID()) 410 Accum = In; 411 } 412 return false; 413} 414 415/// getUIntAtLeastAsBitAs - Return an unsigned integer type that is at least 416/// as big as the specified type. If there is no suitable type, this returns 417/// null. 418const Type *getUIntAtLeastAsBitAs(unsigned NumBits) { 419 if (NumBits > 64) return 0; 420 if (NumBits > 32) return Type::ULongTy; 421 if (NumBits > 16) return Type::UIntTy; 422 if (NumBits > 8) return Type::UShortTy; 423 return Type::UByteTy; 424} 425 426/// CanConvertToScalar - V is a pointer. If we can convert the pointee to a 427/// single scalar integer type, return that type. Further, if the use is not 428/// a completely trivial use that mem2reg could promote, set IsNotTrivial. If 429/// there are no uses of this pointer, return Type::VoidTy to differentiate from 430/// failure. 431/// 432const Type *SROA::CanConvertToScalar(Value *V, bool &IsNotTrivial) { 433 const Type *UsedType = Type::VoidTy; // No uses, no forced type. 434 const TargetData &TD = getAnalysis<TargetData>(); 435 const PointerType *PTy = cast<PointerType>(V->getType()); 436 437 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) { 438 Instruction *User = cast<Instruction>(*UI); 439 440 if (LoadInst *LI = dyn_cast<LoadInst>(User)) { 441 if (MergeInType(LI->getType(), UsedType)) 442 return 0; 443 444 } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) { 445 // Storing the pointer, not the into the value? 446 if (SI->getOperand(0) == V) return 0; 447 448 // NOTE: We could handle storing of FP imms here! 449 450 if (MergeInType(SI->getOperand(0)->getType(), UsedType)) 451 return 0; 452 } else if (CastInst *CI = dyn_cast<CastInst>(User)) { 453 if (!isa<PointerType>(CI->getType())) return 0; 454 IsNotTrivial = true; 455 const Type *SubTy = CanConvertToScalar(CI, IsNotTrivial); 456 if (!SubTy || MergeInType(SubTy, UsedType)) return 0; 457 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) { 458 // Check to see if this is stepping over an element: GEP Ptr, int C 459 if (GEP->getNumOperands() == 2 && isa<ConstantInt>(GEP->getOperand(1))) { 460 unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getRawValue(); 461 unsigned ElSize = TD.getTypeSize(PTy->getElementType()); 462 unsigned BitOffset = Idx*ElSize*8; 463 if (BitOffset > 64 || !isPowerOf2_32(ElSize)) return 0; 464 465 IsNotTrivial = true; 466 const Type *SubElt = CanConvertToScalar(GEP, IsNotTrivial); 467 if (SubElt == 0) return 0; 468 if (SubElt != Type::VoidTy) { 469 const Type *NewTy = 470 getUIntAtLeastAsBitAs(SubElt->getPrimitiveSizeInBits()+BitOffset); 471 if (NewTy == 0 || MergeInType(NewTy, UsedType)) return 0; 472 continue; 473 } 474 } else if (GEP->getNumOperands() == 3 && 475 isa<ConstantInt>(GEP->getOperand(1)) && 476 isa<ConstantInt>(GEP->getOperand(2)) && 477 cast<Constant>(GEP->getOperand(1))->isNullValue()) { 478 // We are stepping into an element, e.g. a structure or an array: 479 // GEP Ptr, int 0, uint C 480 const Type *AggTy = PTy->getElementType(); 481 unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getRawValue(); 482 483 if (const ArrayType *ATy = dyn_cast<ArrayType>(AggTy)) { 484 if (Idx >= ATy->getNumElements()) return 0; // Out of range. 485 } else if (const PackedType *PTy = dyn_cast<PackedType>(AggTy)) { 486 if (Idx >= PTy->getNumElements()) return 0; // Out of range. 487 } else if (isa<StructType>(AggTy)) { 488 // Structs are always ok. 489 } else { 490 return 0; 491 } 492 const Type *NTy = getUIntAtLeastAsBitAs(TD.getTypeSize(AggTy)*8); 493 if (NTy == 0 || MergeInType(NTy, UsedType)) return 0; 494 const Type *SubTy = CanConvertToScalar(GEP, IsNotTrivial); 495 if (SubTy == 0) return 0; 496 if (SubTy != Type::VoidTy && MergeInType(SubTy, UsedType)) 497 return 0; 498 continue; // Everything looks ok 499 } 500 return 0; 501 } else { 502 // Cannot handle this! 503 return 0; 504 } 505 } 506 507 return UsedType; 508} 509 510/// ConvertToScalar - The specified alloca passes the CanConvertToScalar 511/// predicate and is non-trivial. Convert it to something that can be trivially 512/// promoted into a register by mem2reg. 513void SROA::ConvertToScalar(AllocationInst *AI, const Type *ActualTy) { 514 DEBUG(std::cerr << "CONVERT TO SCALAR: " << *AI << " TYPE = " 515 << *ActualTy << "\n"); 516 ++NumConverted; 517 518 BasicBlock *EntryBlock = AI->getParent(); 519 assert(EntryBlock == &EntryBlock->getParent()->front() && 520 "Not in the entry block!"); 521 EntryBlock->getInstList().remove(AI); // Take the alloca out of the program. 522 523 // Create and insert the alloca. 524 AllocaInst *NewAI = new AllocaInst(ActualTy->getUnsignedVersion(), 0, 525 AI->getName(), EntryBlock->begin()); 526 ConvertUsesToScalar(AI, NewAI, 0); 527 delete AI; 528} 529 530 531/// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca 532/// directly. Offset is an offset from the original alloca, in bits that need 533/// to be shifted to the right. By the end of this, there should be no uses of 534/// Ptr. 535void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset) { 536 while (!Ptr->use_empty()) { 537 Instruction *User = cast<Instruction>(Ptr->use_back()); 538 539 if (LoadInst *LI = dyn_cast<LoadInst>(User)) { 540 // The load is a bit extract from NewAI shifted right by Offset bits. 541 Value *NV = new LoadInst(NewAI, LI->getName(), LI); 542 if (Offset && Offset < NV->getType()->getPrimitiveSizeInBits()) 543 NV = new ShiftInst(Instruction::Shr, NV, 544 ConstantUInt::get(Type::UByteTy, Offset), 545 LI->getName(), LI); 546 if (NV->getType() != LI->getType()) 547 NV = new CastInst(NV, LI->getType(), LI->getName(), LI); 548 LI->replaceAllUsesWith(NV); 549 LI->eraseFromParent(); 550 } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) { 551 assert(SI->getOperand(0) != Ptr && "Consistency error!"); 552 553 // Convert the stored type to the actual type, shift it left to insert 554 // then 'or' into place. 555 Value *SV = SI->getOperand(0); 556 if (SV->getType() == NewAI->getType()->getElementType()) { 557 assert(Offset == 0 && "Store out of bounds!"); 558 } else { 559 Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI); 560 // If SV is signed, convert it to unsigned, so that the next cast zero 561 // extends the value. 562 if (SV->getType()->isSigned()) 563 SV = new CastInst(SV, SV->getType()->getUnsignedVersion(), 564 SV->getName(), SI); 565 SV = new CastInst(SV, Old->getType(), SV->getName(), SI); 566 if (Offset && Offset < SV->getType()->getPrimitiveSizeInBits()) 567 SV = new ShiftInst(Instruction::Shl, SV, 568 ConstantUInt::get(Type::UByteTy, Offset), 569 SV->getName()+".adj", SI); 570 // Mask out the bits we are about to insert from the old value. 571 unsigned TotalBits = SV->getType()->getPrimitiveSizeInBits(); 572 unsigned InsertBits = 573 SI->getOperand(0)->getType()->getPrimitiveSizeInBits(); 574 if (TotalBits != InsertBits) { 575 assert(TotalBits > InsertBits); 576 uint64_t Mask = ~(((1ULL << InsertBits)-1) << Offset); 577 if (TotalBits != 64) 578 Mask = Mask & ((1ULL << TotalBits)-1); 579 Old = BinaryOperator::createAnd(Old, 580 ConstantUInt::get(Old->getType(), Mask), 581 Old->getName()+".mask", SI); 582 SV = BinaryOperator::createOr(Old, SV, SV->getName()+".ins", SI); 583 } 584 } 585 new StoreInst(SV, NewAI, SI); 586 SI->eraseFromParent(); 587 588 } else if (CastInst *CI = dyn_cast<CastInst>(User)) { 589 unsigned NewOff = Offset; 590 const TargetData &TD = getAnalysis<TargetData>(); 591 if (TD.isBigEndian()) { 592 // Adjust the pointer. For example, storing 16-bits into a 32-bit 593 // alloca with just a cast makes it modify the top 16-bits. 594 const Type *SrcTy = cast<PointerType>(Ptr->getType())->getElementType(); 595 const Type *DstTy = cast<PointerType>(CI->getType())->getElementType(); 596 int PtrDiffBits = TD.getTypeSize(SrcTy)*8-TD.getTypeSize(DstTy)*8; 597 NewOff += PtrDiffBits; 598 } 599 ConvertUsesToScalar(CI, NewAI, NewOff); 600 CI->eraseFromParent(); 601 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) { 602 const PointerType *AggPtrTy = 603 cast<PointerType>(GEP->getOperand(0)->getType()); 604 const TargetData &TD = getAnalysis<TargetData>(); 605 unsigned AggSizeInBits = TD.getTypeSize(AggPtrTy->getElementType())*8; 606 607 // Check to see if this is stepping over an element: GEP Ptr, int C 608 unsigned NewOffset = Offset; 609 if (GEP->getNumOperands() == 2) { 610 unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getRawValue(); 611 unsigned BitOffset = Idx*AggSizeInBits; 612 613 if (TD.isLittleEndian()) 614 NewOffset += BitOffset; 615 else 616 NewOffset -= BitOffset; 617 618 } else if (GEP->getNumOperands() == 3) { 619 // We know that operand #2 is zero. 620 unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getRawValue(); 621 const Type *AggTy = AggPtrTy->getElementType(); 622 if (const SequentialType *SeqTy = dyn_cast<SequentialType>(AggTy)) { 623 unsigned ElSizeBits = TD.getTypeSize(SeqTy->getElementType())*8; 624 625 if (TD.isLittleEndian()) 626 NewOffset += ElSizeBits*Idx; 627 else 628 NewOffset += AggSizeInBits-ElSizeBits*(Idx+1); 629 } else if (const StructType *STy = dyn_cast<StructType>(AggTy)) { 630 unsigned EltBitOffset = TD.getStructLayout(STy)->MemberOffsets[Idx]*8; 631 632 if (TD.isLittleEndian()) 633 NewOffset += EltBitOffset; 634 else { 635 const PointerType *ElPtrTy = cast<PointerType>(GEP->getType()); 636 unsigned ElSizeBits = TD.getTypeSize(ElPtrTy->getElementType())*8; 637 NewOffset += AggSizeInBits-(EltBitOffset+ElSizeBits); 638 } 639 640 } else { 641 assert(0 && "Unsupported operation!"); 642 abort(); 643 } 644 } else { 645 assert(0 && "Unsupported operation!"); 646 abort(); 647 } 648 ConvertUsesToScalar(GEP, NewAI, NewOffset); 649 GEP->eraseFromParent(); 650 } else { 651 assert(0 && "Unsupported operation!"); 652 abort(); 653 } 654 } 655} 656