1 //===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This family of functions identifies calls to builtin functions that allocate
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "memory-builtins"
16 #include "llvm/Analysis/MemoryBuiltins.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/Statistic.h"
19 #include "llvm/Analysis/ValueTracking.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/GlobalVariable.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/Intrinsics.h"
24 #include "llvm/IR/Metadata.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/MathExtras.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Target/TargetLibraryInfo.h"
30 #include "llvm/Transforms/Utils/Local.h"
34 MallocLike = 1<<0, // allocates
35 CallocLike = 1<<1, // allocates + bzero
36 ReallocLike = 1<<2, // reallocates
38 AllocLike = MallocLike | CallocLike | StrDupLike,
39 AnyAlloc = MallocLike | CallocLike | ReallocLike | StrDupLike
45 unsigned char NumParams;
46 // First and Second size parameters (or -1 if unused)
47 signed char FstParam, SndParam;
50 // FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
51 // know which functions are nounwind, noalias, nocapture parameters, etc.
52 static const AllocFnsTy AllocationFnData[] = {
53 {LibFunc::malloc, MallocLike, 1, 0, -1},
54 {LibFunc::valloc, MallocLike, 1, 0, -1},
55 {LibFunc::Znwj, MallocLike, 1, 0, -1}, // new(unsigned int)
56 {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow)
57 {LibFunc::Znwm, MallocLike, 1, 0, -1}, // new(unsigned long)
58 {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow)
59 {LibFunc::Znaj, MallocLike, 1, 0, -1}, // new[](unsigned int)
60 {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow)
61 {LibFunc::Znam, MallocLike, 1, 0, -1}, // new[](unsigned long)
62 {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow)
63 {LibFunc::posix_memalign, MallocLike, 3, 2, -1},
64 {LibFunc::calloc, CallocLike, 2, 0, 1},
65 {LibFunc::realloc, ReallocLike, 2, 1, -1},
66 {LibFunc::reallocf, ReallocLike, 2, 1, -1},
67 {LibFunc::strdup, StrDupLike, 1, -1, -1},
68 {LibFunc::strndup, StrDupLike, 2, 1, -1}
72 static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) {
73 if (LookThroughBitCast)
74 V = V->stripPointerCasts();
76 CallSite CS(const_cast<Value*>(V));
77 if (!CS.getInstruction())
80 Function *Callee = CS.getCalledFunction();
81 if (!Callee || !Callee->isDeclaration())
86 /// \brief Returns the allocation data for the given value if it is a call to a
87 /// known allocation function, and NULL otherwise.
88 static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy,
89 const TargetLibraryInfo *TLI,
90 bool LookThroughBitCast = false) {
91 Function *Callee = getCalledFunction(V, LookThroughBitCast);
95 // Make sure that the function is available.
96 StringRef FnName = Callee->getName();
98 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
103 for ( ; i < array_lengthof(AllocationFnData); ++i) {
104 if (AllocationFnData[i].Func == TLIFn) {
112 const AllocFnsTy *FnData = &AllocationFnData[i];
113 if ((FnData->AllocTy & AllocTy) == 0)
116 // Check function prototype.
117 int FstParam = FnData->FstParam;
118 int SndParam = FnData->SndParam;
119 FunctionType *FTy = Callee->getFunctionType();
121 if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
122 FTy->getNumParams() == FnData->NumParams &&
124 (FTy->getParamType(FstParam)->isIntegerTy(32) ||
125 FTy->getParamType(FstParam)->isIntegerTy(64))) &&
127 FTy->getParamType(SndParam)->isIntegerTy(32) ||
128 FTy->getParamType(SndParam)->isIntegerTy(64)))
133 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
134 ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
135 return CS && CS.hasFnAttr(Attribute::NoAlias);
139 /// \brief Tests if a value is a call or invoke to a library function that
140 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
142 bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
143 bool LookThroughBitCast) {
144 return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast);
147 /// \brief Tests if a value is a call or invoke to a function that returns a
148 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
149 bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
150 bool LookThroughBitCast) {
151 // it's safe to consider realloc as noalias since accessing the original
152 // pointer is undefined behavior
153 return isAllocationFn(V, TLI, LookThroughBitCast) ||
154 hasNoAliasAttr(V, LookThroughBitCast);
157 /// \brief Tests if a value is a call or invoke to a library function that
158 /// allocates uninitialized memory (such as malloc).
159 bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
160 bool LookThroughBitCast) {
161 return getAllocationData(V, MallocLike, TLI, LookThroughBitCast);
164 /// \brief Tests if a value is a call or invoke to a library function that
165 /// allocates zero-filled memory (such as calloc).
166 bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
167 bool LookThroughBitCast) {
168 return getAllocationData(V, CallocLike, TLI, LookThroughBitCast);
171 /// \brief Tests if a value is a call or invoke to a library function that
172 /// allocates memory (either malloc, calloc, or strdup like).
173 bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
174 bool LookThroughBitCast) {
175 return getAllocationData(V, AllocLike, TLI, LookThroughBitCast);
178 /// \brief Tests if a value is a call or invoke to a library function that
179 /// reallocates memory (such as realloc).
180 bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
181 bool LookThroughBitCast) {
182 return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast);
185 /// extractMallocCall - Returns the corresponding CallInst if the instruction
186 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
187 /// ignore InvokeInst here.
188 const CallInst *llvm::extractMallocCall(const Value *I,
189 const TargetLibraryInfo *TLI) {
190 return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : 0;
193 static Value *computeArraySize(const CallInst *CI, const DataLayout *TD,
194 const TargetLibraryInfo *TLI,
195 bool LookThroughSExt = false) {
199 // The size of the malloc's result type must be known to determine array size.
200 Type *T = getMallocAllocatedType(CI, TLI);
201 if (!T || !T->isSized() || !TD)
204 unsigned ElementSize = TD->getTypeAllocSize(T);
205 if (StructType *ST = dyn_cast<StructType>(T))
206 ElementSize = TD->getStructLayout(ST)->getSizeInBytes();
208 // If malloc call's arg can be determined to be a multiple of ElementSize,
209 // return the multiple. Otherwise, return NULL.
210 Value *MallocArg = CI->getArgOperand(0);
211 Value *Multiple = NULL;
212 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
219 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
220 /// is a call to malloc whose array size can be determined and the array size
221 /// is not constant 1. Otherwise, return NULL.
222 const CallInst *llvm::isArrayMalloc(const Value *I,
223 const DataLayout *TD,
224 const TargetLibraryInfo *TLI) {
225 const CallInst *CI = extractMallocCall(I, TLI);
226 Value *ArraySize = computeArraySize(CI, TD, TLI);
229 ArraySize != ConstantInt::get(CI->getArgOperand(0)->getType(), 1))
232 // CI is a non-array malloc or we can't figure out that it is an array malloc.
236 /// getMallocType - Returns the PointerType resulting from the malloc call.
237 /// The PointerType depends on the number of bitcast uses of the malloc call:
238 /// 0: PointerType is the calls' return type.
239 /// 1: PointerType is the bitcast's result type.
240 /// >1: Unique PointerType cannot be determined, return NULL.
241 PointerType *llvm::getMallocType(const CallInst *CI,
242 const TargetLibraryInfo *TLI) {
243 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
245 PointerType *MallocType = NULL;
246 unsigned NumOfBitCastUses = 0;
248 // Determine if CallInst has a bitcast use.
249 for (Value::const_use_iterator UI = CI->use_begin(), E = CI->use_end();
251 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
252 MallocType = cast<PointerType>(BCI->getDestTy());
256 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
257 if (NumOfBitCastUses == 1)
260 // Malloc call was not bitcast, so type is the malloc function's return type.
261 if (NumOfBitCastUses == 0)
262 return cast<PointerType>(CI->getType());
264 // Type could not be determined.
268 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
269 /// The Type depends on the number of bitcast uses of the malloc call:
270 /// 0: PointerType is the malloc calls' return type.
271 /// 1: PointerType is the bitcast's result type.
272 /// >1: Unique PointerType cannot be determined, return NULL.
273 Type *llvm::getMallocAllocatedType(const CallInst *CI,
274 const TargetLibraryInfo *TLI) {
275 PointerType *PT = getMallocType(CI, TLI);
276 return PT ? PT->getElementType() : NULL;
279 /// getMallocArraySize - Returns the array size of a malloc call. If the
280 /// argument passed to malloc is a multiple of the size of the malloced type,
281 /// then return that multiple. For non-array mallocs, the multiple is
282 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
284 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *TD,
285 const TargetLibraryInfo *TLI,
286 bool LookThroughSExt) {
287 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
288 return computeArraySize(CI, TD, TLI, LookThroughSExt);
292 /// extractCallocCall - Returns the corresponding CallInst if the instruction
293 /// is a calloc call.
294 const CallInst *llvm::extractCallocCall(const Value *I,
295 const TargetLibraryInfo *TLI) {
296 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : 0;
300 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
301 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
302 const CallInst *CI = dyn_cast<CallInst>(I);
305 Function *Callee = CI->getCalledFunction();
306 if (Callee == 0 || !Callee->isDeclaration())
309 StringRef FnName = Callee->getName();
311 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
314 if (TLIFn != LibFunc::free &&
315 TLIFn != LibFunc::ZdlPv && // operator delete(void*)
316 TLIFn != LibFunc::ZdaPv) // operator delete[](void*)
319 // Check free prototype.
320 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
321 // attribute will exist.
322 FunctionType *FTy = Callee->getFunctionType();
323 if (!FTy->getReturnType()->isVoidTy())
325 if (FTy->getNumParams() != 1)
327 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
335 //===----------------------------------------------------------------------===//
336 // Utility functions to compute size of objects.
340 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
341 /// object size in Size if successful, and false otherwise.
342 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
343 /// byval arguments, and global variables.
344 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *TD,
345 const TargetLibraryInfo *TLI, bool RoundToAlign) {
349 ObjectSizeOffsetVisitor Visitor(TD, TLI, Ptr->getContext(), RoundToAlign);
350 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
351 if (!Visitor.bothKnown(Data))
354 APInt ObjSize = Data.first, Offset = Data.second;
355 // check for overflow
356 if (Offset.slt(0) || ObjSize.ult(Offset))
359 Size = (ObjSize - Offset).getZExtValue();
363 /// \brief Compute the size of the underlying object pointed by Ptr. Returns
364 /// true and the object size in Size if successful, and false otherwise.
365 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
366 /// byval arguments, and global variables.
367 bool llvm::getUnderlyingObjectSize(const Value *Ptr, uint64_t &Size,
368 const DataLayout *TD,
369 const TargetLibraryInfo *TLI,
374 ObjectSizeOffsetVisitor Visitor(TD, TLI, Ptr->getContext(), RoundToAlign);
375 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
376 if (!Visitor.knownSize(Data))
379 Size = Data.first.getZExtValue();
384 STATISTIC(ObjectVisitorArgument,
385 "Number of arguments with unsolved size and offset");
386 STATISTIC(ObjectVisitorLoad,
387 "Number of load instructions with unsolved size and offset");
390 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
391 if (RoundToAlign && Align)
392 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
396 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *TD,
397 const TargetLibraryInfo *TLI,
398 LLVMContext &Context,
400 : TD(TD), TLI(TLI), RoundToAlign(RoundToAlign) {
401 IntegerType *IntTy = TD->getIntPtrType(Context);
402 IntTyBits = IntTy->getBitWidth();
403 Zero = APInt::getNullValue(IntTyBits);
406 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
407 V = V->stripPointerCasts();
408 if (Instruction *I = dyn_cast<Instruction>(V)) {
409 // If we have already seen this instruction, bail out. Cycles can happen in
410 // unreachable code after constant propagation.
411 if (!SeenInsts.insert(I))
414 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
415 return visitGEPOperator(*GEP);
418 if (Argument *A = dyn_cast<Argument>(V))
419 return visitArgument(*A);
420 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
421 return visitConstantPointerNull(*P);
422 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
423 return visitGlobalAlias(*GA);
424 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
425 return visitGlobalVariable(*GV);
426 if (UndefValue *UV = dyn_cast<UndefValue>(V))
427 return visitUndefValue(*UV);
428 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
429 if (CE->getOpcode() == Instruction::IntToPtr)
430 return unknown(); // clueless
431 if (CE->getOpcode() == Instruction::GetElementPtr)
432 return visitGEPOperator(cast<GEPOperator>(*CE));
435 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
440 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
441 if (!I.getAllocatedType()->isSized())
444 APInt Size(IntTyBits, TD->getTypeAllocSize(I.getAllocatedType()));
445 if (!I.isArrayAllocation())
446 return std::make_pair(align(Size, I.getAlignment()), Zero);
448 Value *ArraySize = I.getArraySize();
449 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
450 Size *= C->getValue().zextOrSelf(IntTyBits);
451 return std::make_pair(align(Size, I.getAlignment()), Zero);
456 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
457 // no interprocedural analysis is done at the moment
458 if (!A.hasByValAttr()) {
459 ++ObjectVisitorArgument;
462 PointerType *PT = cast<PointerType>(A.getType());
463 APInt Size(IntTyBits, TD->getTypeAllocSize(PT->getElementType()));
464 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
467 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
468 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
473 // handle strdup-like functions separately
474 if (FnData->AllocTy == StrDupLike) {
475 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
479 // strndup limits strlen
480 if (FnData->FstParam > 0) {
481 ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
485 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
486 if (Size.ugt(MaxSize))
489 return std::make_pair(Size, Zero);
492 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
496 APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
497 // size determined by just 1 parameter
498 if (FnData->SndParam < 0)
499 return std::make_pair(Size, Zero);
501 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
505 Size *= Arg->getValue().zextOrSelf(IntTyBits);
506 return std::make_pair(Size, Zero);
508 // TODO: handle more standard functions (+ wchar cousins):
509 // - strdup / strndup
510 // - strcpy / strncpy
511 // - strcat / strncat
512 // - memcpy / memmove
513 // - strcat / strncat
518 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
519 return std::make_pair(Zero, Zero);
523 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
528 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
529 // Easy cases were already folded by previous passes.
533 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
534 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
535 APInt Offset(IntTyBits, 0);
536 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*TD, Offset))
539 return std::make_pair(PtrData.first, PtrData.second + Offset);
542 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
543 if (GA.mayBeOverridden())
545 return compute(GA.getAliasee());
548 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
549 if (!GV.hasDefinitiveInitializer())
552 APInt Size(IntTyBits, TD->getTypeAllocSize(GV.getType()->getElementType()));
553 return std::make_pair(align(Size, GV.getAlignment()), Zero);
556 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
561 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
566 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
567 // too complex to analyze statically.
571 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
572 SizeOffsetType TrueSide = compute(I.getTrueValue());
573 SizeOffsetType FalseSide = compute(I.getFalseValue());
574 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
579 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
580 return std::make_pair(Zero, Zero);
583 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
584 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
589 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *TD,
590 const TargetLibraryInfo *TLI,
591 LLVMContext &Context)
592 : TD(TD), TLI(TLI), Context(Context), Builder(Context, TargetFolder(TD)) {
593 IntTy = TD->getIntPtrType(Context);
594 Zero = ConstantInt::get(IntTy, 0);
597 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
598 SizeOffsetEvalType Result = compute_(V);
600 if (!bothKnown(Result)) {
601 // erase everything that was computed in this iteration from the cache, so
602 // that no dangling references are left behind. We could be a bit smarter if
603 // we kept a dependency graph. It's probably not worth the complexity.
604 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
605 CacheMapTy::iterator CacheIt = CacheMap.find(*I);
606 // non-computable results can be safely cached
607 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
608 CacheMap.erase(CacheIt);
616 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
617 ObjectSizeOffsetVisitor Visitor(TD, TLI, Context);
618 SizeOffsetType Const = Visitor.compute(V);
619 if (Visitor.bothKnown(Const))
620 return std::make_pair(ConstantInt::get(Context, Const.first),
621 ConstantInt::get(Context, Const.second));
623 V = V->stripPointerCasts();
626 CacheMapTy::iterator CacheIt = CacheMap.find(V);
627 if (CacheIt != CacheMap.end())
628 return CacheIt->second;
630 // always generate code immediately before the instruction being
631 // processed, so that the generated code dominates the same BBs
632 Instruction *PrevInsertPoint = Builder.GetInsertPoint();
633 if (Instruction *I = dyn_cast<Instruction>(V))
634 Builder.SetInsertPoint(I);
636 // record the pointers that were handled in this run, so that they can be
637 // cleaned later if something fails
640 // now compute the size and offset
641 SizeOffsetEvalType Result;
642 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
643 Result = visitGEPOperator(*GEP);
644 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
646 } else if (isa<Argument>(V) ||
647 (isa<ConstantExpr>(V) &&
648 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
649 isa<GlobalAlias>(V) ||
650 isa<GlobalVariable>(V)) {
651 // ignore values where we cannot do more than what ObjectSizeVisitor can
654 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
660 Builder.SetInsertPoint(PrevInsertPoint);
662 // Don't reuse CacheIt since it may be invalid at this point.
663 CacheMap[V] = Result;
667 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
668 if (!I.getAllocatedType()->isSized())
672 assert(I.isArrayAllocation());
673 Value *ArraySize = I.getArraySize();
674 Value *Size = ConstantInt::get(ArraySize->getType(),
675 TD->getTypeAllocSize(I.getAllocatedType()));
676 Size = Builder.CreateMul(Size, ArraySize);
677 return std::make_pair(Size, Zero);
680 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
681 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
686 // handle strdup-like functions separately
687 if (FnData->AllocTy == StrDupLike) {
692 Value *FirstArg = CS.getArgument(FnData->FstParam);
693 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
694 if (FnData->SndParam < 0)
695 return std::make_pair(FirstArg, Zero);
697 Value *SecondArg = CS.getArgument(FnData->SndParam);
698 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
699 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
700 return std::make_pair(Size, Zero);
702 // TODO: handle more standard functions (+ wchar cousins):
703 // - strdup / strndup
704 // - strcpy / strncpy
705 // - strcat / strncat
706 // - memcpy / memmove
707 // - strcat / strncat
712 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
717 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
722 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
723 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
724 if (!bothKnown(PtrData))
727 Value *Offset = EmitGEPOffset(&Builder, *TD, &GEP, /*NoAssumptions=*/true);
728 Offset = Builder.CreateAdd(PtrData.second, Offset);
729 return std::make_pair(PtrData.first, Offset);
732 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
737 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
741 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
742 // create 2 PHIs: one for size and another for offset
743 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
744 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
746 // insert right away in the cache to handle recursive PHIs
747 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
749 // compute offset/size for each PHI incoming pointer
750 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
751 Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt());
752 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
754 if (!bothKnown(EdgeData)) {
755 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
756 OffsetPHI->eraseFromParent();
757 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
758 SizePHI->eraseFromParent();
761 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
762 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
765 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
766 if ((Tmp = SizePHI->hasConstantValue())) {
768 SizePHI->replaceAllUsesWith(Size);
769 SizePHI->eraseFromParent();
771 if ((Tmp = OffsetPHI->hasConstantValue())) {
773 OffsetPHI->replaceAllUsesWith(Offset);
774 OffsetPHI->eraseFromParent();
776 return std::make_pair(Size, Offset);
779 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
780 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
781 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
783 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
785 if (TrueSide == FalseSide)
788 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
790 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
792 return std::make_pair(Size, Offset);
795 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
796 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');