1 //===- llvm/Analysis/MemoryBuiltins.h- Calls to memory builtins -*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This family of functions identifies calls to builtin functions that allocate 11 // or free memory. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_ANALYSIS_MEMORYBUILTINS_H 16 #define LLVM_ANALYSIS_MEMORYBUILTINS_H 17 18 #include "llvm/ADT/DenseMap.h" 19 #include "llvm/ADT/SmallPtrSet.h" 20 #include "llvm/Analysis/TargetFolder.h" 21 #include "llvm/IR/IRBuilder.h" 22 #include "llvm/IR/InstVisitor.h" 23 #include "llvm/IR/Operator.h" 24 #include "llvm/IR/ValueHandle.h" 25 #include "llvm/Support/DataTypes.h" 26 27 namespace llvm { 28 class CallInst; 29 class PointerType; 30 class DataLayout; 31 class TargetLibraryInfo; 32 class Type; 33 class Value; 34 35 /// \brief Tests if a value is a call or invoke to a library function that 36 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup 37 /// like). 38 bool isAllocationFn(const Value *V, const TargetLibraryInfo *TLI, 39 bool LookThroughBitCast = false); 40 41 /// \brief Tests if a value is a call or invoke to a function that returns a 42 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions). 43 bool isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI, 44 bool LookThroughBitCast = false); 45 46 /// \brief Tests if a value is a call or invoke to a library function that 47 /// allocates uninitialized memory (such as malloc). 48 bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 49 bool LookThroughBitCast = false); 50 51 /// \brief Tests if a value is a call or invoke to a library function that 52 /// allocates zero-filled memory (such as calloc). 53 bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 54 bool LookThroughBitCast = false); 55 56 /// \brief Tests if a value is a call or invoke to a library function that 57 /// allocates memory similar to malloc or calloc. 58 bool isMallocOrCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 59 bool LookThroughBitCast = false); 60 61 /// \brief Tests if a value is a call or invoke to a library function that 62 /// allocates memory (either malloc, calloc, or strdup like). 63 bool isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 64 bool LookThroughBitCast = false); 65 66 //===----------------------------------------------------------------------===// 67 // malloc Call Utility Functions. 68 // 69 70 /// extractMallocCall - Returns the corresponding CallInst if the instruction 71 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we 72 /// ignore InvokeInst here. 73 const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI); 74 static inline CallInst *extractMallocCall(Value *I, 75 const TargetLibraryInfo *TLI) { 76 return const_cast<CallInst*>(extractMallocCall((const Value*)I, TLI)); 77 } 78 79 /// getMallocType - Returns the PointerType resulting from the malloc call. 80 /// The PointerType depends on the number of bitcast uses of the malloc call: 81 /// 0: PointerType is the malloc calls' return type. 82 /// 1: PointerType is the bitcast's result type. 83 /// >1: Unique PointerType cannot be determined, return NULL. 84 PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI); 85 86 /// getMallocAllocatedType - Returns the Type allocated by malloc call. 87 /// The Type depends on the number of bitcast uses of the malloc call: 88 /// 0: PointerType is the malloc calls' return type. 89 /// 1: PointerType is the bitcast's result type. 90 /// >1: Unique PointerType cannot be determined, return NULL. 91 Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI); 92 93 /// getMallocArraySize - Returns the array size of a malloc call. If the 94 /// argument passed to malloc is a multiple of the size of the malloced type, 95 /// then return that multiple. For non-array mallocs, the multiple is 96 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be 97 /// determined. 98 Value *getMallocArraySize(CallInst *CI, const DataLayout &DL, 99 const TargetLibraryInfo *TLI, 100 bool LookThroughSExt = false); 101 102 //===----------------------------------------------------------------------===// 103 // calloc Call Utility Functions. 104 // 105 106 /// extractCallocCall - Returns the corresponding CallInst if the instruction 107 /// is a calloc call. 108 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI); 109 static inline CallInst *extractCallocCall(Value *I, 110 const TargetLibraryInfo *TLI) { 111 return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI)); 112 } 113 114 115 //===----------------------------------------------------------------------===// 116 // free Call Utility Functions. 117 // 118 119 /// isFreeCall - Returns non-null if the value is a call to the builtin free() 120 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI); 121 122 static inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) { 123 return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI)); 124 } 125 126 127 //===----------------------------------------------------------------------===// 128 // Utility functions to compute size of objects. 129 // 130 131 /// Various options to control the behavior of getObjectSize. 132 struct ObjectSizeOpts { 133 /// Controls how we handle conditional statements with unknown conditions. 134 enum class Mode : uint8_t { 135 /// Fail to evaluate an unknown condition. 136 Exact, 137 /// Evaluate all branches of an unknown condition. If all evaluations 138 /// succeed, pick the minimum size. 139 Min, 140 /// Same as Min, except we pick the maximum size of all of the branches. 141 Max 142 }; 143 144 /// How we want to evaluate this object's size. 145 Mode EvalMode = Mode::Exact; 146 /// Whether to round the result up to the alignment of allocas, byval 147 /// arguments, and global variables. 148 bool RoundToAlign = false; 149 /// If this is true, null pointers in address space 0 will be treated as 150 /// though they can't be evaluated. Otherwise, null is always considered to 151 /// point to a 0 byte region of memory. 152 bool NullIsUnknownSize = false; 153 }; 154 155 /// \brief Compute the size of the object pointed by Ptr. Returns true and the 156 /// object size in Size if successful, and false otherwise. In this context, by 157 /// object we mean the region of memory starting at Ptr to the end of the 158 /// underlying object pointed to by Ptr. 159 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL, 160 const TargetLibraryInfo *TLI, ObjectSizeOpts Opts = {}); 161 162 /// Try to turn a call to @llvm.objectsize into an integer value of the given 163 /// Type. Returns null on failure. 164 /// If MustSucceed is true, this function will not return null, and may return 165 /// conservative values governed by the second argument of the call to 166 /// objectsize. 167 ConstantInt *lowerObjectSizeCall(IntrinsicInst *ObjectSize, 168 const DataLayout &DL, 169 const TargetLibraryInfo *TLI, 170 bool MustSucceed); 171 172 typedef std::pair<APInt, APInt> SizeOffsetType; 173 174 /// \brief Evaluate the size and offset of an object pointed to by a Value* 175 /// statically. Fails if size or offset are not known at compile time. 176 class ObjectSizeOffsetVisitor 177 : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> { 178 179 const DataLayout &DL; 180 const TargetLibraryInfo *TLI; 181 ObjectSizeOpts Options; 182 unsigned IntTyBits; 183 APInt Zero; 184 SmallPtrSet<Instruction *, 8> SeenInsts; 185 186 APInt align(APInt Size, uint64_t Align); 187 188 SizeOffsetType unknown() { 189 return std::make_pair(APInt(), APInt()); 190 } 191 192 public: 193 ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI, 194 LLVMContext &Context, ObjectSizeOpts Options = {}); 195 196 SizeOffsetType compute(Value *V); 197 198 static bool knownSize(const SizeOffsetType &SizeOffset) { 199 return SizeOffset.first.getBitWidth() > 1; 200 } 201 202 static bool knownOffset(const SizeOffsetType &SizeOffset) { 203 return SizeOffset.second.getBitWidth() > 1; 204 } 205 206 static bool bothKnown(const SizeOffsetType &SizeOffset) { 207 return knownSize(SizeOffset) && knownOffset(SizeOffset); 208 } 209 210 // These are "private", except they can't actually be made private. Only 211 // compute() should be used by external users. 212 SizeOffsetType visitAllocaInst(AllocaInst &I); 213 SizeOffsetType visitArgument(Argument &A); 214 SizeOffsetType visitCallSite(CallSite CS); 215 SizeOffsetType visitConstantPointerNull(ConstantPointerNull&); 216 SizeOffsetType visitExtractElementInst(ExtractElementInst &I); 217 SizeOffsetType visitExtractValueInst(ExtractValueInst &I); 218 SizeOffsetType visitGEPOperator(GEPOperator &GEP); 219 SizeOffsetType visitGlobalAlias(GlobalAlias &GA); 220 SizeOffsetType visitGlobalVariable(GlobalVariable &GV); 221 SizeOffsetType visitIntToPtrInst(IntToPtrInst&); 222 SizeOffsetType visitLoadInst(LoadInst &I); 223 SizeOffsetType visitPHINode(PHINode&); 224 SizeOffsetType visitSelectInst(SelectInst &I); 225 SizeOffsetType visitUndefValue(UndefValue&); 226 SizeOffsetType visitInstruction(Instruction &I); 227 }; 228 229 typedef std::pair<Value*, Value*> SizeOffsetEvalType; 230 231 232 /// \brief Evaluate the size and offset of an object pointed to by a Value*. 233 /// May create code to compute the result at run-time. 234 class ObjectSizeOffsetEvaluator 235 : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> { 236 237 typedef IRBuilder<TargetFolder> BuilderTy; 238 typedef std::pair<WeakTrackingVH, WeakTrackingVH> WeakEvalType; 239 typedef DenseMap<const Value*, WeakEvalType> CacheMapTy; 240 typedef SmallPtrSet<const Value*, 8> PtrSetTy; 241 242 const DataLayout &DL; 243 const TargetLibraryInfo *TLI; 244 LLVMContext &Context; 245 BuilderTy Builder; 246 IntegerType *IntTy; 247 Value *Zero; 248 CacheMapTy CacheMap; 249 PtrSetTy SeenVals; 250 bool RoundToAlign; 251 252 SizeOffsetEvalType unknown() { 253 return std::make_pair(nullptr, nullptr); 254 } 255 SizeOffsetEvalType compute_(Value *V); 256 257 public: 258 ObjectSizeOffsetEvaluator(const DataLayout &DL, const TargetLibraryInfo *TLI, 259 LLVMContext &Context, bool RoundToAlign = false); 260 SizeOffsetEvalType compute(Value *V); 261 262 bool knownSize(SizeOffsetEvalType SizeOffset) { 263 return SizeOffset.first; 264 } 265 266 bool knownOffset(SizeOffsetEvalType SizeOffset) { 267 return SizeOffset.second; 268 } 269 270 bool anyKnown(SizeOffsetEvalType SizeOffset) { 271 return knownSize(SizeOffset) || knownOffset(SizeOffset); 272 } 273 274 bool bothKnown(SizeOffsetEvalType SizeOffset) { 275 return knownSize(SizeOffset) && knownOffset(SizeOffset); 276 } 277 278 // The individual instruction visitors should be treated as private. 279 SizeOffsetEvalType visitAllocaInst(AllocaInst &I); 280 SizeOffsetEvalType visitCallSite(CallSite CS); 281 SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I); 282 SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I); 283 SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP); 284 SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&); 285 SizeOffsetEvalType visitLoadInst(LoadInst &I); 286 SizeOffsetEvalType visitPHINode(PHINode &PHI); 287 SizeOffsetEvalType visitSelectInst(SelectInst &I); 288 SizeOffsetEvalType visitInstruction(Instruction &I); 289 }; 290 291 } // End llvm namespace 292 293 #endif 294