1 //===- ScalarReplAggregates.cpp - Scalar Replacement of Aggregates --------===//
3 // The LLVM Compiler Infrastructure
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.
8 //===----------------------------------------------------------------------===//
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.
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.
20 //===----------------------------------------------------------------------===//
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/Debug.h"
32 #include "llvm/Support/GetElementPtrTypeIterator.h"
33 #include "llvm/Support/MathExtras.h"
34 #include "llvm/Support/Compiler.h"
35 #include "llvm/ADT/Statistic.h"
36 #include "llvm/ADT/StringExtras.h"
41 Statistic<> NumReplaced("scalarrepl", "Number of allocas broken up");
42 Statistic<> NumPromoted("scalarrepl", "Number of allocas promoted");
43 Statistic<> NumConverted("scalarrepl",
44 "Number of aggregates converted to scalar");
46 struct VISIBILITY_HIDDEN SROA : public FunctionPass {
47 bool runOnFunction(Function &F);
49 bool performScalarRepl(Function &F);
50 bool performPromotion(Function &F);
52 // getAnalysisUsage - This pass does not require any passes, but we know it
53 // will not alter the CFG, so say so.
54 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
55 AU.addRequired<DominatorTree>();
56 AU.addRequired<DominanceFrontier>();
57 AU.addRequired<TargetData>();
62 int isSafeElementUse(Value *Ptr);
63 int isSafeUseOfAllocation(Instruction *User);
64 int isSafeAllocaToScalarRepl(AllocationInst *AI);
65 void CanonicalizeAllocaUsers(AllocationInst *AI);
66 AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
68 const Type *CanConvertToScalar(Value *V, bool &IsNotTrivial);
69 void ConvertToScalar(AllocationInst *AI, const Type *Ty);
70 void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset);
73 RegisterPass<SROA> X("scalarrepl", "Scalar Replacement of Aggregates");
76 // Public interface to the ScalarReplAggregates pass
77 FunctionPass *llvm::createScalarReplAggregatesPass() { return new SROA(); }
80 bool SROA::runOnFunction(Function &F) {
81 bool Changed = performPromotion(F);
83 bool LocalChange = performScalarRepl(F);
84 if (!LocalChange) break; // No need to repromote if no scalarrepl
86 LocalChange = performPromotion(F);
87 if (!LocalChange) break; // No need to re-scalarrepl if no promotion
94 bool SROA::performPromotion(Function &F) {
95 std::vector<AllocaInst*> Allocas;
96 const TargetData &TD = getAnalysis<TargetData>();
97 DominatorTree &DT = getAnalysis<DominatorTree>();
98 DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
100 BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
102 bool Changed = false;
107 // Find allocas that are safe to promote, by looking at all instructions in
109 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
110 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
111 if (isAllocaPromotable(AI, TD))
112 Allocas.push_back(AI);
114 if (Allocas.empty()) break;
116 PromoteMemToReg(Allocas, DT, DF, TD);
117 NumPromoted += Allocas.size();
124 // performScalarRepl - This algorithm is a simple worklist driven algorithm,
125 // which runs on all of the malloc/alloca instructions in the function, removing
126 // them if they are only used by getelementptr instructions.
128 bool SROA::performScalarRepl(Function &F) {
129 std::vector<AllocationInst*> WorkList;
131 // Scan the entry basic block, adding any alloca's and mallocs to the worklist
132 BasicBlock &BB = F.getEntryBlock();
133 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
134 if (AllocationInst *A = dyn_cast<AllocationInst>(I))
135 WorkList.push_back(A);
137 // Process the worklist
138 bool Changed = false;
139 while (!WorkList.empty()) {
140 AllocationInst *AI = WorkList.back();
143 // If we can turn this aggregate value (potentially with casts) into a
144 // simple scalar value that can be mem2reg'd into a register value.
145 bool IsNotTrivial = false;
146 if (const Type *ActualType = CanConvertToScalar(AI, IsNotTrivial))
147 if (IsNotTrivial && ActualType != Type::VoidTy) {
148 ConvertToScalar(AI, ActualType);
153 // We cannot transform the allocation instruction if it is an array
154 // allocation (allocations OF arrays are ok though), and an allocation of a
155 // scalar value cannot be decomposed at all.
157 if (AI->isArrayAllocation() ||
158 (!isa<StructType>(AI->getAllocatedType()) &&
159 !isa<ArrayType>(AI->getAllocatedType()))) continue;
161 // Check that all of the users of the allocation are capable of being
163 switch (isSafeAllocaToScalarRepl(AI)) {
164 default: assert(0 && "Unexpected value!");
165 case 0: // Not safe to scalar replace.
167 case 1: // Safe, but requires cleanup/canonicalizations first
168 CanonicalizeAllocaUsers(AI);
169 case 3: // Safe to scalar replace.
173 DEBUG(std::cerr << "Found inst to xform: " << *AI);
176 std::vector<AllocaInst*> ElementAllocas;
177 if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
178 ElementAllocas.reserve(ST->getNumContainedTypes());
179 for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
180 AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
182 AI->getName() + "." + utostr(i), AI);
183 ElementAllocas.push_back(NA);
184 WorkList.push_back(NA); // Add to worklist for recursive processing
187 const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
188 ElementAllocas.reserve(AT->getNumElements());
189 const Type *ElTy = AT->getElementType();
190 for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
191 AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(),
192 AI->getName() + "." + utostr(i), AI);
193 ElementAllocas.push_back(NA);
194 WorkList.push_back(NA); // Add to worklist for recursive processing
198 // Now that we have created the alloca instructions that we want to use,
199 // expand the getelementptr instructions to use them.
201 while (!AI->use_empty()) {
202 Instruction *User = cast<Instruction>(AI->use_back());
203 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
204 // We now know that the GEP is of the form: GEP <ptr>, 0, <cst>
206 (unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
208 assert(Idx < ElementAllocas.size() && "Index out of range?");
209 AllocaInst *AllocaToUse = ElementAllocas[Idx];
212 if (GEPI->getNumOperands() == 3) {
213 // Do not insert a new getelementptr instruction with zero indices, only
214 // to have it optimized out later.
215 RepValue = AllocaToUse;
217 // We are indexing deeply into the structure, so we still need a
218 // getelement ptr instruction to finish the indexing. This may be
219 // expanded itself once the worklist is rerun.
221 std::string OldName = GEPI->getName(); // Steal the old name.
222 std::vector<Value*> NewArgs;
223 NewArgs.push_back(Constant::getNullValue(Type::IntTy));
224 NewArgs.insert(NewArgs.end(), GEPI->op_begin()+3, GEPI->op_end());
226 RepValue = new GetElementPtrInst(AllocaToUse, NewArgs, OldName, GEPI);
229 // Move all of the users over to the new GEP.
230 GEPI->replaceAllUsesWith(RepValue);
231 // Delete the old GEP
232 GEPI->eraseFromParent();
235 // Finally, delete the Alloca instruction
236 AI->getParent()->getInstList().erase(AI);
244 /// isSafeElementUse - Check to see if this use is an allowed use for a
245 /// getelementptr instruction of an array aggregate allocation.
247 int SROA::isSafeElementUse(Value *Ptr) {
248 for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
250 Instruction *User = cast<Instruction>(*I);
251 switch (User->getOpcode()) {
252 case Instruction::Load: break;
253 case Instruction::Store:
254 // Store is ok if storing INTO the pointer, not storing the pointer
255 if (User->getOperand(0) == Ptr) return 0;
257 case Instruction::GetElementPtr: {
258 GetElementPtrInst *GEP = cast<GetElementPtrInst>(User);
259 if (GEP->getNumOperands() > 1) {
260 if (!isa<Constant>(GEP->getOperand(1)) ||
261 !cast<Constant>(GEP->getOperand(1))->isNullValue())
262 return 0; // Using pointer arithmetic to navigate the array...
264 if (!isSafeElementUse(GEP)) return 0;
268 DEBUG(std::cerr << " Transformation preventing inst: " << *User);
272 return 3; // All users look ok :)
275 /// AllUsersAreLoads - Return true if all users of this value are loads.
276 static bool AllUsersAreLoads(Value *Ptr) {
277 for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
279 if (cast<Instruction>(*I)->getOpcode() != Instruction::Load)
284 /// isSafeUseOfAllocation - Check to see if this user is an allowed use for an
285 /// aggregate allocation.
287 int SROA::isSafeUseOfAllocation(Instruction *User) {
288 if (!isa<GetElementPtrInst>(User)) return 0;
290 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
291 gep_type_iterator I = gep_type_begin(GEPI), E = gep_type_end(GEPI);
293 // The GEP is not safe to transform if not of the form "GEP <ptr>, 0, <cst>".
295 I.getOperand() != Constant::getNullValue(I.getOperand()->getType()))
299 if (I == E) return 0; // ran out of GEP indices??
301 // If this is a use of an array allocation, do a bit more checking for sanity.
302 if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
303 uint64_t NumElements = AT->getNumElements();
305 if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
306 // Check to make sure that index falls within the array. If not,
307 // something funny is going on, so we won't do the optimization.
309 if (cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue() >= NumElements)
312 // We cannot scalar repl this level of the array unless any array
313 // sub-indices are in-range constants. In particular, consider:
314 // A[0][i]. We cannot know that the user isn't doing invalid things like
315 // allowing i to index an out-of-range subscript that accesses A[1].
317 // Scalar replacing *just* the outer index of the array is probably not
318 // going to be a win anyway, so just give up.
319 for (++I; I != E && isa<ArrayType>(*I); ++I) {
320 const ArrayType *SubArrayTy = cast<ArrayType>(*I);
321 uint64_t NumElements = SubArrayTy->getNumElements();
322 if (!isa<ConstantInt>(I.getOperand())) return 0;
323 if (cast<ConstantInt>(I.getOperand())->getZExtValue() >= NumElements)
328 // If this is an array index and the index is not constant, we cannot
329 // promote... that is unless the array has exactly one or two elements in
330 // it, in which case we CAN promote it, but we have to canonicalize this
331 // out if this is the only problem.
332 if ((NumElements == 1 || NumElements == 2) &&
333 AllUsersAreLoads(GEPI))
334 return 1; // Canonicalization required!
339 // If there are any non-simple uses of this getelementptr, make sure to reject
341 return isSafeElementUse(GEPI);
344 /// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of
345 /// an aggregate can be broken down into elements. Return 0 if not, 3 if safe,
346 /// or 1 if safe after canonicalization has been performed.
348 int SROA::isSafeAllocaToScalarRepl(AllocationInst *AI) {
349 // Loop over the use list of the alloca. We can only transform it if all of
350 // the users are safe to transform.
353 for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
355 isSafe &= isSafeUseOfAllocation(cast<Instruction>(*I));
357 DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
362 // If we require cleanup, isSafe is now 1, otherwise it is 3.
366 /// CanonicalizeAllocaUsers - If SROA reported that it can promote the specified
367 /// allocation, but only if cleaned up, perform the cleanups required.
368 void SROA::CanonicalizeAllocaUsers(AllocationInst *AI) {
369 // At this point, we know that the end result will be SROA'd and promoted, so
370 // we can insert ugly code if required so long as sroa+mem2reg will clean it
372 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
374 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(*UI++);
375 gep_type_iterator I = gep_type_begin(GEPI);
378 if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
379 uint64_t NumElements = AT->getNumElements();
381 if (!isa<ConstantInt>(I.getOperand())) {
382 if (NumElements == 1) {
383 GEPI->setOperand(2, Constant::getNullValue(Type::IntTy));
385 assert(NumElements == 2 && "Unhandled case!");
386 // All users of the GEP must be loads. At each use of the GEP, insert
387 // two loads of the appropriate indexed GEP and select between them.
388 Value *IsOne = BinaryOperator::createSetNE(I.getOperand(),
389 Constant::getNullValue(I.getOperand()->getType()),
391 // Insert the new GEP instructions, which are properly indexed.
392 std::vector<Value*> Indices(GEPI->op_begin()+1, GEPI->op_end());
393 Indices[1] = Constant::getNullValue(Type::IntTy);
394 Value *ZeroIdx = new GetElementPtrInst(GEPI->getOperand(0), Indices,
395 GEPI->getName()+".0", GEPI);
396 Indices[1] = ConstantInt::get(Type::IntTy, 1);
397 Value *OneIdx = new GetElementPtrInst(GEPI->getOperand(0), Indices,
398 GEPI->getName()+".1", GEPI);
399 // Replace all loads of the variable index GEP with loads from both
400 // indexes and a select.
401 while (!GEPI->use_empty()) {
402 LoadInst *LI = cast<LoadInst>(GEPI->use_back());
403 Value *Zero = new LoadInst(ZeroIdx, LI->getName()+".0", LI);
404 Value *One = new LoadInst(OneIdx , LI->getName()+".1", LI);
405 Value *R = new SelectInst(IsOne, One, Zero, LI->getName(), LI);
406 LI->replaceAllUsesWith(R);
407 LI->eraseFromParent();
409 GEPI->eraseFromParent();
416 /// MergeInType - Add the 'In' type to the accumulated type so far. If the
417 /// types are incompatible, return true, otherwise update Accum and return
420 /// There are two cases we handle here:
421 /// 1) An effectively integer union, where the pieces are stored into as
422 /// smaller integers (common with byte swap and other idioms).
423 /// 2) A union of a vector and its elements. Here we turn element accesses
424 /// into insert/extract element operations.
425 static bool MergeInType(const Type *In, const Type *&Accum,
426 const TargetData &TD) {
427 // If this is our first type, just use it.
428 const PackedType *PTy;
429 if (Accum == Type::VoidTy || In == Accum) {
431 } else if (In->isIntegral() && Accum->isIntegral()) { // integer union.
432 // Otherwise pick whichever type is larger.
433 if (In->getTypeID() > Accum->getTypeID())
435 } else if (isa<PointerType>(In) && isa<PointerType>(Accum)) {
436 // Pointer unions just stay as one of the pointers.
437 } else if ((PTy = dyn_cast<PackedType>(Accum)) &&
438 PTy->getElementType() == In) {
439 // Accum is a vector, and we are accessing an element: ok.
440 } else if ((PTy = dyn_cast<PackedType>(In)) &&
441 PTy->getElementType() == Accum) {
442 // In is a vector, and accum is an element: ok, remember In.
444 } else if (isa<PointerType>(In) && Accum->isIntegral()) {
445 // Pointer/Integer unions merge together as integers.
446 return MergeInType(TD.getIntPtrType(), Accum, TD);
447 } else if (isa<PointerType>(Accum) && In->isIntegral()) {
448 // Pointer/Integer unions merge together as integers.
449 Accum = TD.getIntPtrType();
450 return MergeInType(In, Accum, TD);
457 /// getUIntAtLeastAsBitAs - Return an unsigned integer type that is at least
458 /// as big as the specified type. If there is no suitable type, this returns
460 const Type *getUIntAtLeastAsBitAs(unsigned NumBits) {
461 if (NumBits > 64) return 0;
462 if (NumBits > 32) return Type::ULongTy;
463 if (NumBits > 16) return Type::UIntTy;
464 if (NumBits > 8) return Type::UShortTy;
465 return Type::UByteTy;
468 /// CanConvertToScalar - V is a pointer. If we can convert the pointee to a
469 /// single scalar integer type, return that type. Further, if the use is not
470 /// a completely trivial use that mem2reg could promote, set IsNotTrivial. If
471 /// there are no uses of this pointer, return Type::VoidTy to differentiate from
474 const Type *SROA::CanConvertToScalar(Value *V, bool &IsNotTrivial) {
475 const Type *UsedType = Type::VoidTy; // No uses, no forced type.
476 const TargetData &TD = getAnalysis<TargetData>();
477 const PointerType *PTy = cast<PointerType>(V->getType());
479 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
480 Instruction *User = cast<Instruction>(*UI);
482 if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
483 if (MergeInType(LI->getType(), UsedType, TD))
486 } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
487 // Storing the pointer, not the into the value?
488 if (SI->getOperand(0) == V) return 0;
490 // NOTE: We could handle storing of FP imms into integers here!
492 if (MergeInType(SI->getOperand(0)->getType(), UsedType, TD))
494 } else if (CastInst *CI = dyn_cast<CastInst>(User)) {
495 if (!isa<PointerType>(CI->getType())) return 0;
497 const Type *SubTy = CanConvertToScalar(CI, IsNotTrivial);
498 if (!SubTy || MergeInType(SubTy, UsedType, TD)) return 0;
499 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
500 // Check to see if this is stepping over an element: GEP Ptr, int C
501 if (GEP->getNumOperands() == 2 && isa<ConstantInt>(GEP->getOperand(1))) {
502 unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getZExtValue();
503 unsigned ElSize = TD.getTypeSize(PTy->getElementType());
504 unsigned BitOffset = Idx*ElSize*8;
505 if (BitOffset > 64 || !isPowerOf2_32(ElSize)) return 0;
508 const Type *SubElt = CanConvertToScalar(GEP, IsNotTrivial);
509 if (SubElt == 0) return 0;
510 if (SubElt != Type::VoidTy && SubElt->isInteger()) {
512 getUIntAtLeastAsBitAs(TD.getTypeSize(SubElt)*8+BitOffset);
513 if (NewTy == 0 || MergeInType(NewTy, UsedType, TD)) return 0;
516 } else if (GEP->getNumOperands() == 3 &&
517 isa<ConstantInt>(GEP->getOperand(1)) &&
518 isa<ConstantInt>(GEP->getOperand(2)) &&
519 cast<Constant>(GEP->getOperand(1))->isNullValue()) {
520 // We are stepping into an element, e.g. a structure or an array:
521 // GEP Ptr, int 0, uint C
522 const Type *AggTy = PTy->getElementType();
523 unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
525 if (const ArrayType *ATy = dyn_cast<ArrayType>(AggTy)) {
526 if (Idx >= ATy->getNumElements()) return 0; // Out of range.
527 } else if (const PackedType *PackedTy = dyn_cast<PackedType>(AggTy)) {
528 // Getting an element of the packed vector.
529 if (Idx >= PackedTy->getNumElements()) return 0; // Out of range.
531 // Merge in the packed type.
532 if (MergeInType(PackedTy, UsedType, TD)) return 0;
534 const Type *SubTy = CanConvertToScalar(GEP, IsNotTrivial);
535 if (SubTy == 0) return 0;
537 if (SubTy != Type::VoidTy && MergeInType(SubTy, UsedType, TD))
540 // We'll need to change this to an insert/extract element operation.
542 continue; // Everything looks ok
544 } else if (isa<StructType>(AggTy)) {
545 // Structs are always ok.
549 const Type *NTy = getUIntAtLeastAsBitAs(TD.getTypeSize(AggTy)*8);
550 if (NTy == 0 || MergeInType(NTy, UsedType, TD)) return 0;
551 const Type *SubTy = CanConvertToScalar(GEP, IsNotTrivial);
552 if (SubTy == 0) return 0;
553 if (SubTy != Type::VoidTy && MergeInType(SubTy, UsedType, TD))
555 continue; // Everything looks ok
559 // Cannot handle this!
567 /// ConvertToScalar - The specified alloca passes the CanConvertToScalar
568 /// predicate and is non-trivial. Convert it to something that can be trivially
569 /// promoted into a register by mem2reg.
570 void SROA::ConvertToScalar(AllocationInst *AI, const Type *ActualTy) {
571 DEBUG(std::cerr << "CONVERT TO SCALAR: " << *AI << " TYPE = "
572 << *ActualTy << "\n");
575 BasicBlock *EntryBlock = AI->getParent();
576 assert(EntryBlock == &EntryBlock->getParent()->front() &&
577 "Not in the entry block!");
578 EntryBlock->getInstList().remove(AI); // Take the alloca out of the program.
580 if (ActualTy->isInteger())
581 ActualTy = ActualTy->getUnsignedVersion();
583 // Create and insert the alloca.
584 AllocaInst *NewAI = new AllocaInst(ActualTy, 0, AI->getName(),
585 EntryBlock->begin());
586 ConvertUsesToScalar(AI, NewAI, 0);
591 /// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
592 /// directly. This happens when we are converting an "integer union" to a
593 /// single integer scalar, or when we are converting a "vector union" to a
594 /// vector with insert/extractelement instructions.
596 /// Offset is an offset from the original alloca, in bits that need to be
597 /// shifted to the right. By the end of this, there should be no uses of Ptr.
598 void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset) {
599 bool isVectorInsert = isa<PackedType>(NewAI->getType()->getElementType());
600 const TargetData &TD = getAnalysis<TargetData>();
601 while (!Ptr->use_empty()) {
602 Instruction *User = cast<Instruction>(Ptr->use_back());
604 if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
605 // The load is a bit extract from NewAI shifted right by Offset bits.
606 Value *NV = new LoadInst(NewAI, LI->getName(), LI);
607 if (NV->getType() != LI->getType()) {
608 if (const PackedType *PTy = dyn_cast<PackedType>(NV->getType())) {
609 // Must be an element access.
610 unsigned Elt = Offset/(TD.getTypeSize(PTy->getElementType())*8);
611 NV = new ExtractElementInst(NV, ConstantInt::get(Type::UIntTy, Elt),
614 assert(NV->getType()->isInteger() && "Unknown promotion!");
615 if (Offset && Offset < TD.getTypeSize(NV->getType())*8)
616 NV = new ShiftInst(Instruction::Shr, NV,
617 ConstantInt::get(Type::UByteTy, Offset),
619 NV = new CastInst(NV, LI->getType(), LI->getName(), LI);
622 LI->replaceAllUsesWith(NV);
623 LI->eraseFromParent();
624 } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
625 assert(SI->getOperand(0) != Ptr && "Consistency error!");
627 // Convert the stored type to the actual type, shift it left to insert
628 // then 'or' into place.
629 Value *SV = SI->getOperand(0);
630 const Type *AllocaType = NewAI->getType()->getElementType();
631 if (SV->getType() != AllocaType) {
632 Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI);
634 if (const PackedType *PTy = dyn_cast<PackedType>(AllocaType)) {
635 // Must be an element insertion.
636 unsigned Elt = Offset/(TD.getTypeSize(PTy->getElementType())*8);
637 SV = new InsertElementInst(Old, SV,
638 ConstantInt::get(Type::UIntTy, Elt),
641 // If SV is signed, convert it to unsigned, so that the next cast zero
642 // extends the value.
643 if (SV->getType()->isSigned())
644 SV = new CastInst(SV, SV->getType()->getUnsignedVersion(),
646 SV = new CastInst(SV, Old->getType(), SV->getName(), SI);
647 if (Offset && Offset < TD.getTypeSize(SV->getType())*8)
648 SV = new ShiftInst(Instruction::Shl, SV,
649 ConstantInt::get(Type::UByteTy, Offset),
650 SV->getName()+".adj", SI);
651 // Mask out the bits we are about to insert from the old value.
652 unsigned TotalBits = TD.getTypeSize(SV->getType())*8;
653 unsigned InsertBits = TD.getTypeSize(SI->getOperand(0)->getType())*8;
654 if (TotalBits != InsertBits) {
655 assert(TotalBits > InsertBits);
656 uint64_t Mask = ~(((1ULL << InsertBits)-1) << Offset);
658 Mask = Mask & ((1ULL << TotalBits)-1);
659 Old = BinaryOperator::createAnd(Old,
660 ConstantInt::get(Old->getType(), Mask),
661 Old->getName()+".mask", SI);
662 SV = BinaryOperator::createOr(Old, SV, SV->getName()+".ins", SI);
666 new StoreInst(SV, NewAI, SI);
667 SI->eraseFromParent();
669 } else if (CastInst *CI = dyn_cast<CastInst>(User)) {
670 unsigned NewOff = Offset;
671 const TargetData &TD = getAnalysis<TargetData>();
672 if (TD.isBigEndian() && !isVectorInsert) {
673 // Adjust the pointer. For example, storing 16-bits into a 32-bit
674 // alloca with just a cast makes it modify the top 16-bits.
675 const Type *SrcTy = cast<PointerType>(Ptr->getType())->getElementType();
676 const Type *DstTy = cast<PointerType>(CI->getType())->getElementType();
677 int PtrDiffBits = TD.getTypeSize(SrcTy)*8-TD.getTypeSize(DstTy)*8;
678 NewOff += PtrDiffBits;
680 ConvertUsesToScalar(CI, NewAI, NewOff);
681 CI->eraseFromParent();
682 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
683 const PointerType *AggPtrTy =
684 cast<PointerType>(GEP->getOperand(0)->getType());
685 const TargetData &TD = getAnalysis<TargetData>();
686 unsigned AggSizeInBits = TD.getTypeSize(AggPtrTy->getElementType())*8;
688 // Check to see if this is stepping over an element: GEP Ptr, int C
689 unsigned NewOffset = Offset;
690 if (GEP->getNumOperands() == 2) {
691 unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getZExtValue();
692 unsigned BitOffset = Idx*AggSizeInBits;
694 if (TD.isLittleEndian() || isVectorInsert)
695 NewOffset += BitOffset;
697 NewOffset -= BitOffset;
699 } else if (GEP->getNumOperands() == 3) {
700 // We know that operand #2 is zero.
701 unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
702 const Type *AggTy = AggPtrTy->getElementType();
703 if (const SequentialType *SeqTy = dyn_cast<SequentialType>(AggTy)) {
704 unsigned ElSizeBits = TD.getTypeSize(SeqTy->getElementType())*8;
706 if (TD.isLittleEndian() || isVectorInsert)
707 NewOffset += ElSizeBits*Idx;
709 NewOffset += AggSizeInBits-ElSizeBits*(Idx+1);
710 } else if (const StructType *STy = dyn_cast<StructType>(AggTy)) {
711 unsigned EltBitOffset = TD.getStructLayout(STy)->MemberOffsets[Idx]*8;
713 if (TD.isLittleEndian() || isVectorInsert)
714 NewOffset += EltBitOffset;
716 const PointerType *ElPtrTy = cast<PointerType>(GEP->getType());
717 unsigned ElSizeBits = TD.getTypeSize(ElPtrTy->getElementType())*8;
718 NewOffset += AggSizeInBits-(EltBitOffset+ElSizeBits);
722 assert(0 && "Unsupported operation!");
726 assert(0 && "Unsupported operation!");
729 ConvertUsesToScalar(GEP, NewAI, NewOffset);
730 GEP->eraseFromParent();
732 assert(0 && "Unsupported operation!");