Home | History | Annotate | Download | only in Analysis 
      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 
     36 /// \brief Tests if a value is a call or invoke to a library function that
     37 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
     38 /// like).
     39 bool isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
     40                     bool LookThroughBitCast = false);
     41 
     42 /// \brief Tests if a value is a call or invoke to a function that returns a
     43 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
     44 bool isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
     45                  bool LookThroughBitCast = false);
     46 
     47 /// \brief Tests if a value is a call or invoke to a library function that
     48 /// allocates uninitialized memory (such as malloc).
     49 bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
     50                     bool LookThroughBitCast = false);
     51 
     52 /// \brief Tests if a value is a call or invoke to a library function that
     53 /// allocates zero-filled memory (such as calloc).
     54 bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
     55                     bool LookThroughBitCast = false);
     56 
     57 /// \brief Tests if a value is a call or invoke to a library function that
     58 /// allocates memory (either malloc, calloc, or strdup like).
     59 bool isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
     60                    bool LookThroughBitCast = false);
     61 
     62 /// \brief Tests if a value is a call or invoke to a library function that
     63 /// reallocates memory (such as realloc).
     64 bool isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
     65                      bool LookThroughBitCast = false);
     66 
     67 /// \brief Tests if a value is a call or invoke to a library function that
     68 /// allocates memory and never returns null (such as operator new).
     69 bool isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
     70                          bool LookThroughBitCast = false);
     71 
     72 //===----------------------------------------------------------------------===//
     73 //  malloc Call Utility Functions.
     74 //
     75 
     76 /// extractMallocCall - Returns the corresponding CallInst if the instruction
     77 /// is a malloc call.  Since CallInst::CreateMalloc() only creates calls, we
     78 /// ignore InvokeInst here.
     79 const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI);
     80 static inline CallInst *extractMallocCall(Value *I,
     81                                           const TargetLibraryInfo *TLI) {
     82   return const_cast<CallInst*>(extractMallocCall((const Value*)I, TLI));
     83 }
     84 
     85 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
     86 /// is a call to malloc whose array size can be determined and the array size
     87 /// is not constant 1.  Otherwise, return NULL.
     88 const CallInst *isArrayMalloc(const Value *I, const DataLayout *DL,
     89                               const TargetLibraryInfo *TLI);
     90 
     91 /// getMallocType - Returns the PointerType resulting from the malloc call.
     92 /// The PointerType depends on the number of bitcast uses of the malloc call:
     93 ///   0: PointerType is the malloc calls' return type.
     94 ///   1: PointerType is the bitcast's result type.
     95 ///  >1: Unique PointerType cannot be determined, return NULL.
     96 PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
     97 
     98 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
     99 /// The Type depends on the number of bitcast uses of the malloc call:
    100 ///   0: PointerType is the malloc calls' return type.
    101 ///   1: PointerType is the bitcast's result type.
    102 ///  >1: Unique PointerType cannot be determined, return NULL.
    103 Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
    104 
    105 /// getMallocArraySize - Returns the array size of a malloc call.  If the
    106 /// argument passed to malloc is a multiple of the size of the malloced type,
    107 /// then return that multiple.  For non-array mallocs, the multiple is
    108 /// constant 1.  Otherwise, return NULL for mallocs whose array size cannot be
    109 /// determined.
    110 Value *getMallocArraySize(CallInst *CI, const DataLayout *DL,
    111                           const TargetLibraryInfo *TLI,
    112                           bool LookThroughSExt = false);
    113 
    114 
    115 //===----------------------------------------------------------------------===//
    116 //  calloc Call Utility Functions.
    117 //
    118 
    119 /// extractCallocCall - Returns the corresponding CallInst if the instruction
    120 /// is a calloc call.
    121 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
    122 static inline CallInst *extractCallocCall(Value *I,
    123                                           const TargetLibraryInfo *TLI) {
    124   return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
    125 }
    126 
    127 
    128 //===----------------------------------------------------------------------===//
    129 //  free Call Utility Functions.
    130 //
    131 
    132 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
    133 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
    134 
    135 static inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
    136   return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
    137 }
    138 
    139 
    140 //===----------------------------------------------------------------------===//
    141 //  Utility functions to compute size of objects.
    142 //
    143 
    144 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
    145 /// object size in Size if successful, and false otherwise. In this context, by
    146 /// object we mean the region of memory starting at Ptr to the end of the
    147 /// underlying object pointed to by Ptr.
    148 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
    149 /// byval arguments, and global variables.
    150 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL,
    151                    const TargetLibraryInfo *TLI, bool RoundToAlign = false);
    152 
    153 
    154 
    155 typedef std::pair<APInt, APInt> SizeOffsetType;
    156 
    157 /// \brief Evaluate the size and offset of an object pointed to by a Value*
    158 /// statically. Fails if size or offset are not known at compile time.
    159 class ObjectSizeOffsetVisitor
    160   : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
    161 
    162   const DataLayout *DL;
    163   const TargetLibraryInfo *TLI;
    164   bool RoundToAlign;
    165   unsigned IntTyBits;
    166   APInt Zero;
    167   SmallPtrSet<Instruction *, 8> SeenInsts;
    168 
    169   APInt align(APInt Size, uint64_t Align);
    170 
    171   SizeOffsetType unknown() {
    172     return std::make_pair(APInt(), APInt());
    173   }
    174 
    175 public:
    176   ObjectSizeOffsetVisitor(const DataLayout *DL, const TargetLibraryInfo *TLI,
    177                           LLVMContext &Context, bool RoundToAlign = false);
    178 
    179   SizeOffsetType compute(Value *V);
    180 
    181   bool knownSize(SizeOffsetType &SizeOffset) {
    182     return SizeOffset.first.getBitWidth() > 1;
    183   }
    184 
    185   bool knownOffset(SizeOffsetType &SizeOffset) {
    186     return SizeOffset.second.getBitWidth() > 1;
    187   }
    188 
    189   bool bothKnown(SizeOffsetType &SizeOffset) {
    190     return knownSize(SizeOffset) && knownOffset(SizeOffset);
    191   }
    192 
    193   // These are "private", except they can't actually be made private. Only
    194   // compute() should be used by external users.
    195   SizeOffsetType visitAllocaInst(AllocaInst &I);
    196   SizeOffsetType visitArgument(Argument &A);
    197   SizeOffsetType visitCallSite(CallSite CS);
    198   SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
    199   SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
    200   SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
    201   SizeOffsetType visitGEPOperator(GEPOperator &GEP);
    202   SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
    203   SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
    204   SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
    205   SizeOffsetType visitLoadInst(LoadInst &I);
    206   SizeOffsetType visitPHINode(PHINode&);
    207   SizeOffsetType visitSelectInst(SelectInst &I);
    208   SizeOffsetType visitUndefValue(UndefValue&);
    209   SizeOffsetType visitInstruction(Instruction &I);
    210 };
    211 
    212 typedef std::pair<Value*, Value*> SizeOffsetEvalType;
    213 
    214 
    215 /// \brief Evaluate the size and offset of an object pointed to by a Value*.
    216 /// May create code to compute the result at run-time.
    217 class ObjectSizeOffsetEvaluator
    218   : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
    219 
    220   typedef IRBuilder<true, TargetFolder> BuilderTy;
    221   typedef std::pair<WeakVH, WeakVH> WeakEvalType;
    222   typedef DenseMap<const Value*, WeakEvalType> CacheMapTy;
    223   typedef SmallPtrSet<const Value*, 8> PtrSetTy;
    224 
    225   const DataLayout *DL;
    226   const TargetLibraryInfo *TLI;
    227   LLVMContext &Context;
    228   BuilderTy Builder;
    229   IntegerType *IntTy;
    230   Value *Zero;
    231   CacheMapTy CacheMap;
    232   PtrSetTy SeenVals;
    233   bool RoundToAlign;
    234 
    235   SizeOffsetEvalType unknown() {
    236     return std::make_pair(nullptr, nullptr);
    237   }
    238   SizeOffsetEvalType compute_(Value *V);
    239 
    240 public:
    241   ObjectSizeOffsetEvaluator(const DataLayout *DL, const TargetLibraryInfo *TLI,
    242                             LLVMContext &Context, bool RoundToAlign = false);
    243   SizeOffsetEvalType compute(Value *V);
    244 
    245   bool knownSize(SizeOffsetEvalType SizeOffset) {
    246     return SizeOffset.first;
    247   }
    248 
    249   bool knownOffset(SizeOffsetEvalType SizeOffset) {
    250     return SizeOffset.second;
    251   }
    252 
    253   bool anyKnown(SizeOffsetEvalType SizeOffset) {
    254     return knownSize(SizeOffset) || knownOffset(SizeOffset);
    255   }
    256 
    257   bool bothKnown(SizeOffsetEvalType SizeOffset) {
    258     return knownSize(SizeOffset) && knownOffset(SizeOffset);
    259   }
    260 
    261   // The individual instruction visitors should be treated as private.
    262   SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
    263   SizeOffsetEvalType visitCallSite(CallSite CS);
    264   SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
    265   SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
    266   SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
    267   SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
    268   SizeOffsetEvalType visitLoadInst(LoadInst &I);
    269   SizeOffsetEvalType visitPHINode(PHINode &PHI);
    270   SizeOffsetEvalType visitSelectInst(SelectInst &I);
    271   SizeOffsetEvalType visitInstruction(Instruction &I);
    272 };
    273 
    274 } // End llvm namespace
    275 
    276 #endif
    277