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 OpNewLike = 1<<0, // allocates; never returns null
35 MallocLike = 1<<1 | OpNewLike, // allocates; may return null
36 CallocLike = 1<<2, // allocates + bzero
37 ReallocLike = 1<<3, // reallocates
39 AllocLike = MallocLike | CallocLike | StrDupLike,
40 AnyAlloc = AllocLike | ReallocLike
46 unsigned char NumParams;
47 // First and Second size parameters (or -1 if unused)
48 signed char FstParam, SndParam;
51 // FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
52 // know which functions are nounwind, noalias, nocapture parameters, etc.
53 static const AllocFnsTy AllocationFnData[] = {
54 {LibFunc::malloc, MallocLike, 1, 0, -1},
55 {LibFunc::valloc, MallocLike, 1, 0, -1},
56 {LibFunc::Znwj, OpNewLike, 1, 0, -1}, // new(unsigned int)
57 {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow)
58 {LibFunc::Znwm, OpNewLike, 1, 0, -1}, // new(unsigned long)
59 {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow)
60 {LibFunc::Znaj, OpNewLike, 1, 0, -1}, // new[](unsigned int)
61 {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow)
62 {LibFunc::Znam, OpNewLike, 1, 0, -1}, // new[](unsigned long)
63 {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow)
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}
69 // TODO: Handle "int posix_memalign(void **, size_t, size_t)"
73 static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) {
74 if (LookThroughBitCast)
75 V = V->stripPointerCasts();
77 CallSite CS(const_cast<Value*>(V));
78 if (!CS.getInstruction())
84 Function *Callee = CS.getCalledFunction();
85 if (!Callee || !Callee->isDeclaration())
90 /// \brief Returns the allocation data for the given value if it is a call to a
91 /// known allocation function, and NULL otherwise.
92 static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy,
93 const TargetLibraryInfo *TLI,
94 bool LookThroughBitCast = false) {
96 if (isa<IntrinsicInst>(V))
99 Function *Callee = getCalledFunction(V, LookThroughBitCast);
103 // Make sure that the function is available.
104 StringRef FnName = Callee->getName();
106 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
111 for ( ; i < array_lengthof(AllocationFnData); ++i) {
112 if (AllocationFnData[i].Func == TLIFn) {
120 const AllocFnsTy *FnData = &AllocationFnData[i];
121 if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
124 // Check function prototype.
125 int FstParam = FnData->FstParam;
126 int SndParam = FnData->SndParam;
127 FunctionType *FTy = Callee->getFunctionType();
129 if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
130 FTy->getNumParams() == FnData->NumParams &&
132 (FTy->getParamType(FstParam)->isIntegerTy(32) ||
133 FTy->getParamType(FstParam)->isIntegerTy(64))) &&
135 FTy->getParamType(SndParam)->isIntegerTy(32) ||
136 FTy->getParamType(SndParam)->isIntegerTy(64)))
141 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
142 ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
143 return CS && CS.hasFnAttr(Attribute::NoAlias);
147 /// \brief Tests if a value is a call or invoke to a library function that
148 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
150 bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
151 bool LookThroughBitCast) {
152 return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast);
155 /// \brief Tests if a value is a call or invoke to a function that returns a
156 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
157 bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
158 bool LookThroughBitCast) {
159 // it's safe to consider realloc as noalias since accessing the original
160 // pointer is undefined behavior
161 return isAllocationFn(V, TLI, LookThroughBitCast) ||
162 hasNoAliasAttr(V, LookThroughBitCast);
165 /// \brief Tests if a value is a call or invoke to a library function that
166 /// allocates uninitialized memory (such as malloc).
167 bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
168 bool LookThroughBitCast) {
169 return getAllocationData(V, MallocLike, TLI, LookThroughBitCast);
172 /// \brief Tests if a value is a call or invoke to a library function that
173 /// allocates zero-filled memory (such as calloc).
174 bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
175 bool LookThroughBitCast) {
176 return getAllocationData(V, CallocLike, TLI, LookThroughBitCast);
179 /// \brief Tests if a value is a call or invoke to a library function that
180 /// allocates memory (either malloc, calloc, or strdup like).
181 bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
182 bool LookThroughBitCast) {
183 return getAllocationData(V, AllocLike, TLI, LookThroughBitCast);
186 /// \brief Tests if a value is a call or invoke to a library function that
187 /// reallocates memory (such as realloc).
188 bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
189 bool LookThroughBitCast) {
190 return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast);
193 /// \brief Tests if a value is a call or invoke to a library function that
194 /// allocates memory and never returns null (such as operator new).
195 bool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
196 bool LookThroughBitCast) {
197 return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast);
200 /// extractMallocCall - Returns the corresponding CallInst if the instruction
201 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
202 /// ignore InvokeInst here.
203 const CallInst *llvm::extractMallocCall(const Value *I,
204 const TargetLibraryInfo *TLI) {
205 return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : 0;
208 static Value *computeArraySize(const CallInst *CI, const DataLayout *DL,
209 const TargetLibraryInfo *TLI,
210 bool LookThroughSExt = false) {
214 // The size of the malloc's result type must be known to determine array size.
215 Type *T = getMallocAllocatedType(CI, TLI);
216 if (!T || !T->isSized() || !DL)
219 unsigned ElementSize = DL->getTypeAllocSize(T);
220 if (StructType *ST = dyn_cast<StructType>(T))
221 ElementSize = DL->getStructLayout(ST)->getSizeInBytes();
223 // If malloc call's arg can be determined to be a multiple of ElementSize,
224 // return the multiple. Otherwise, return NULL.
225 Value *MallocArg = CI->getArgOperand(0);
227 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
234 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
235 /// is a call to malloc whose array size can be determined and the array size
236 /// is not constant 1. Otherwise, return NULL.
237 const CallInst *llvm::isArrayMalloc(const Value *I,
238 const DataLayout *DL,
239 const TargetLibraryInfo *TLI) {
240 const CallInst *CI = extractMallocCall(I, TLI);
241 Value *ArraySize = computeArraySize(CI, DL, TLI);
243 if (ConstantInt *ConstSize = dyn_cast_or_null<ConstantInt>(ArraySize))
244 if (ConstSize->isOne())
247 // CI is a non-array malloc or we can't figure out that it is an array malloc.
251 /// getMallocType - Returns the PointerType resulting from the malloc call.
252 /// The PointerType depends on the number of bitcast uses of the malloc call:
253 /// 0: PointerType is the calls' return type.
254 /// 1: PointerType is the bitcast's result type.
255 /// >1: Unique PointerType cannot be determined, return NULL.
256 PointerType *llvm::getMallocType(const CallInst *CI,
257 const TargetLibraryInfo *TLI) {
258 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
260 PointerType *MallocType = 0;
261 unsigned NumOfBitCastUses = 0;
263 // Determine if CallInst has a bitcast use.
264 for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
266 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
267 MallocType = cast<PointerType>(BCI->getDestTy());
271 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
272 if (NumOfBitCastUses == 1)
275 // Malloc call was not bitcast, so type is the malloc function's return type.
276 if (NumOfBitCastUses == 0)
277 return cast<PointerType>(CI->getType());
279 // Type could not be determined.
283 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
284 /// The Type depends on the number of bitcast uses of the malloc call:
285 /// 0: PointerType is the malloc calls' return type.
286 /// 1: PointerType is the bitcast's result type.
287 /// >1: Unique PointerType cannot be determined, return NULL.
288 Type *llvm::getMallocAllocatedType(const CallInst *CI,
289 const TargetLibraryInfo *TLI) {
290 PointerType *PT = getMallocType(CI, TLI);
291 return PT ? PT->getElementType() : 0;
294 /// getMallocArraySize - Returns the array size of a malloc call. If the
295 /// argument passed to malloc is a multiple of the size of the malloced type,
296 /// then return that multiple. For non-array mallocs, the multiple is
297 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
299 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *DL,
300 const TargetLibraryInfo *TLI,
301 bool LookThroughSExt) {
302 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
303 return computeArraySize(CI, DL, TLI, LookThroughSExt);
307 /// extractCallocCall - Returns the corresponding CallInst if the instruction
308 /// is a calloc call.
309 const CallInst *llvm::extractCallocCall(const Value *I,
310 const TargetLibraryInfo *TLI) {
311 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : 0;
315 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
316 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
317 const CallInst *CI = dyn_cast<CallInst>(I);
318 if (!CI || isa<IntrinsicInst>(CI))
320 Function *Callee = CI->getCalledFunction();
321 if (Callee == 0 || !Callee->isDeclaration())
324 StringRef FnName = Callee->getName();
326 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
329 unsigned ExpectedNumParams;
330 if (TLIFn == LibFunc::free ||
331 TLIFn == LibFunc::ZdlPv || // operator delete(void*)
332 TLIFn == LibFunc::ZdaPv) // operator delete[](void*)
333 ExpectedNumParams = 1;
334 else if (TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
335 TLIFn == LibFunc::ZdaPvRKSt9nothrow_t) // delete[](void*, nothrow)
336 ExpectedNumParams = 2;
340 // Check free prototype.
341 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
342 // attribute will exist.
343 FunctionType *FTy = Callee->getFunctionType();
344 if (!FTy->getReturnType()->isVoidTy())
346 if (FTy->getNumParams() != ExpectedNumParams)
348 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
356 //===----------------------------------------------------------------------===//
357 // Utility functions to compute size of objects.
361 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
362 /// object size in Size if successful, and false otherwise.
363 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
364 /// byval arguments, and global variables.
365 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL,
366 const TargetLibraryInfo *TLI, bool RoundToAlign) {
370 ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign);
371 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
372 if (!Visitor.bothKnown(Data))
375 APInt ObjSize = Data.first, Offset = Data.second;
376 // check for overflow
377 if (Offset.slt(0) || ObjSize.ult(Offset))
380 Size = (ObjSize - Offset).getZExtValue();
385 STATISTIC(ObjectVisitorArgument,
386 "Number of arguments with unsolved size and offset");
387 STATISTIC(ObjectVisitorLoad,
388 "Number of load instructions with unsolved size and offset");
391 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
392 if (RoundToAlign && Align)
393 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
397 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *DL,
398 const TargetLibraryInfo *TLI,
399 LLVMContext &Context,
401 : DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) {
402 // Pointer size must be rechecked for each object visited since it could have
403 // a different address space.
406 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
407 IntTyBits = DL->getPointerTypeSizeInBits(V->getType());
408 Zero = APInt::getNullValue(IntTyBits);
410 V = V->stripPointerCasts();
411 if (Instruction *I = dyn_cast<Instruction>(V)) {
412 // If we have already seen this instruction, bail out. Cycles can happen in
413 // unreachable code after constant propagation.
414 if (!SeenInsts.insert(I))
417 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
418 return visitGEPOperator(*GEP);
421 if (Argument *A = dyn_cast<Argument>(V))
422 return visitArgument(*A);
423 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
424 return visitConstantPointerNull(*P);
425 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
426 return visitGlobalAlias(*GA);
427 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
428 return visitGlobalVariable(*GV);
429 if (UndefValue *UV = dyn_cast<UndefValue>(V))
430 return visitUndefValue(*UV);
431 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
432 if (CE->getOpcode() == Instruction::IntToPtr)
433 return unknown(); // clueless
434 if (CE->getOpcode() == Instruction::GetElementPtr)
435 return visitGEPOperator(cast<GEPOperator>(*CE));
438 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
443 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
444 if (!I.getAllocatedType()->isSized())
447 APInt Size(IntTyBits, DL->getTypeAllocSize(I.getAllocatedType()));
448 if (!I.isArrayAllocation())
449 return std::make_pair(align(Size, I.getAlignment()), Zero);
451 Value *ArraySize = I.getArraySize();
452 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
453 Size *= C->getValue().zextOrSelf(IntTyBits);
454 return std::make_pair(align(Size, I.getAlignment()), Zero);
459 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
460 // no interprocedural analysis is done at the moment
461 if (!A.hasByValOrInAllocaAttr()) {
462 ++ObjectVisitorArgument;
465 PointerType *PT = cast<PointerType>(A.getType());
466 APInt Size(IntTyBits, DL->getTypeAllocSize(PT->getElementType()));
467 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
470 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
471 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
476 // handle strdup-like functions separately
477 if (FnData->AllocTy == StrDupLike) {
478 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
482 // strndup limits strlen
483 if (FnData->FstParam > 0) {
484 ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
488 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
489 if (Size.ugt(MaxSize))
492 return std::make_pair(Size, Zero);
495 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
499 APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
500 // size determined by just 1 parameter
501 if (FnData->SndParam < 0)
502 return std::make_pair(Size, Zero);
504 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
508 Size *= Arg->getValue().zextOrSelf(IntTyBits);
509 return std::make_pair(Size, Zero);
511 // TODO: handle more standard functions (+ wchar cousins):
512 // - strdup / strndup
513 // - strcpy / strncpy
514 // - strcat / strncat
515 // - memcpy / memmove
516 // - strcat / strncat
521 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
522 return std::make_pair(Zero, Zero);
526 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
531 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
532 // Easy cases were already folded by previous passes.
536 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
537 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
538 APInt Offset(IntTyBits, 0);
539 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*DL, Offset))
542 return std::make_pair(PtrData.first, PtrData.second + Offset);
545 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
546 if (GA.mayBeOverridden())
548 return compute(GA.getAliasee());
551 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
552 if (!GV.hasDefinitiveInitializer())
555 APInt Size(IntTyBits, DL->getTypeAllocSize(GV.getType()->getElementType()));
556 return std::make_pair(align(Size, GV.getAlignment()), Zero);
559 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
564 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
569 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
570 // too complex to analyze statically.
574 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
575 SizeOffsetType TrueSide = compute(I.getTrueValue());
576 SizeOffsetType FalseSide = compute(I.getFalseValue());
577 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
582 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
583 return std::make_pair(Zero, Zero);
586 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
587 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
591 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *DL,
592 const TargetLibraryInfo *TLI,
593 LLVMContext &Context,
595 : DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
596 RoundToAlign(RoundToAlign) {
597 // IntTy and Zero must be set for each compute() since the address space may
598 // be different for later objects.
601 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
602 // XXX - Are vectors of pointers possible here?
603 IntTy = cast<IntegerType>(DL->getIntPtrType(V->getType()));
604 Zero = ConstantInt::get(IntTy, 0);
606 SizeOffsetEvalType Result = compute_(V);
608 if (!bothKnown(Result)) {
609 // erase everything that was computed in this iteration from the cache, so
610 // that no dangling references are left behind. We could be a bit smarter if
611 // we kept a dependency graph. It's probably not worth the complexity.
612 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
613 CacheMapTy::iterator CacheIt = CacheMap.find(*I);
614 // non-computable results can be safely cached
615 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
616 CacheMap.erase(CacheIt);
624 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
625 ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
626 SizeOffsetType Const = Visitor.compute(V);
627 if (Visitor.bothKnown(Const))
628 return std::make_pair(ConstantInt::get(Context, Const.first),
629 ConstantInt::get(Context, Const.second));
631 V = V->stripPointerCasts();
634 CacheMapTy::iterator CacheIt = CacheMap.find(V);
635 if (CacheIt != CacheMap.end())
636 return CacheIt->second;
638 // always generate code immediately before the instruction being
639 // processed, so that the generated code dominates the same BBs
640 Instruction *PrevInsertPoint = Builder.GetInsertPoint();
641 if (Instruction *I = dyn_cast<Instruction>(V))
642 Builder.SetInsertPoint(I);
644 // now compute the size and offset
645 SizeOffsetEvalType Result;
647 // Record the pointers that were handled in this run, so that they can be
648 // cleaned later if something fails. We also use this set to break cycles that
649 // can occur in dead code.
650 if (!SeenVals.insert(V)) {
652 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
653 Result = visitGEPOperator(*GEP);
654 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
656 } else if (isa<Argument>(V) ||
657 (isa<ConstantExpr>(V) &&
658 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
659 isa<GlobalAlias>(V) ||
660 isa<GlobalVariable>(V)) {
661 // ignore values where we cannot do more than what ObjectSizeVisitor can
664 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
670 Builder.SetInsertPoint(PrevInsertPoint);
672 // Don't reuse CacheIt since it may be invalid at this point.
673 CacheMap[V] = Result;
677 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
678 if (!I.getAllocatedType()->isSized())
682 assert(I.isArrayAllocation());
683 Value *ArraySize = I.getArraySize();
684 Value *Size = ConstantInt::get(ArraySize->getType(),
685 DL->getTypeAllocSize(I.getAllocatedType()));
686 Size = Builder.CreateMul(Size, ArraySize);
687 return std::make_pair(Size, Zero);
690 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
691 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
696 // handle strdup-like functions separately
697 if (FnData->AllocTy == StrDupLike) {
702 Value *FirstArg = CS.getArgument(FnData->FstParam);
703 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
704 if (FnData->SndParam < 0)
705 return std::make_pair(FirstArg, Zero);
707 Value *SecondArg = CS.getArgument(FnData->SndParam);
708 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
709 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
710 return std::make_pair(Size, Zero);
712 // TODO: handle more standard functions (+ wchar cousins):
713 // - strdup / strndup
714 // - strcpy / strncpy
715 // - strcat / strncat
716 // - memcpy / memmove
717 // - strcat / strncat
722 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
727 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
732 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
733 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
734 if (!bothKnown(PtrData))
737 Value *Offset = EmitGEPOffset(&Builder, *DL, &GEP, /*NoAssumptions=*/true);
738 Offset = Builder.CreateAdd(PtrData.second, Offset);
739 return std::make_pair(PtrData.first, Offset);
742 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
747 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
751 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
752 // create 2 PHIs: one for size and another for offset
753 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
754 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
756 // insert right away in the cache to handle recursive PHIs
757 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
759 // compute offset/size for each PHI incoming pointer
760 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
761 Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt());
762 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
764 if (!bothKnown(EdgeData)) {
765 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
766 OffsetPHI->eraseFromParent();
767 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
768 SizePHI->eraseFromParent();
771 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
772 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
775 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
776 if ((Tmp = SizePHI->hasConstantValue())) {
778 SizePHI->replaceAllUsesWith(Size);
779 SizePHI->eraseFromParent();
781 if ((Tmp = OffsetPHI->hasConstantValue())) {
783 OffsetPHI->replaceAllUsesWith(Offset);
784 OffsetPHI->eraseFromParent();
786 return std::make_pair(Size, Offset);
789 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
790 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
791 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
793 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
795 if (TrueSide == FalseSide)
798 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
800 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
802 return std::make_pair(Size, Offset);
805 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
806 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');