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      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/IR/IRBuilder.h"
     21 #include "llvm/IR/Operator.h"
     22 #include "llvm/InstVisitor.h"
     23 #include "llvm/Support/DataTypes.h"
     24 #include "llvm/Support/TargetFolder.h"
     25 #include "llvm/Support/ValueHandle.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 
     68 //===----------------------------------------------------------------------===//
     69 //  malloc Call Utility Functions.
     70 //
     71 
     72 /// extractMallocCall - Returns the corresponding CallInst if the instruction
     73 /// is a malloc call.  Since CallInst::CreateMalloc() only creates calls, we
     74 /// ignore InvokeInst here.
     75 const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI);
     76 static inline CallInst *extractMallocCall(Value *I,
     77                                           const TargetLibraryInfo *TLI) {
     78   return const_cast<CallInst*>(extractMallocCall((const Value*)I, TLI));
     79 }
     80 
     81 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
     82 /// is a call to malloc whose array size can be determined and the array size
     83 /// is not constant 1.  Otherwise, return NULL.
     84 const CallInst *isArrayMalloc(const Value *I, const DataLayout *TD,
     85                               const TargetLibraryInfo *TLI);
     86 
     87 /// getMallocType - Returns the PointerType resulting from the malloc call.
     88 /// The PointerType depends on the number of bitcast uses of the malloc call:
     89 ///   0: PointerType is the malloc calls' return type.
     90 ///   1: PointerType is the bitcast's result type.
     91 ///  >1: Unique PointerType cannot be determined, return NULL.
     92 PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
     93 
     94 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
     95 /// The Type depends on the number of bitcast uses of the malloc call:
     96 ///   0: PointerType is the malloc calls' return type.
     97 ///   1: PointerType is the bitcast's result type.
     98 ///  >1: Unique PointerType cannot be determined, return NULL.
     99 Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
    100 
    101 /// getMallocArraySize - Returns the array size of a malloc call.  If the
    102 /// argument passed to malloc is a multiple of the size of the malloced type,
    103 /// then return that multiple.  For non-array mallocs, the multiple is
    104 /// constant 1.  Otherwise, return NULL for mallocs whose array size cannot be
    105 /// determined.
    106 Value *getMallocArraySize(CallInst *CI, const DataLayout *TD,
    107                           const TargetLibraryInfo *TLI,
    108                           bool LookThroughSExt = false);
    109 
    110 
    111 //===----------------------------------------------------------------------===//
    112 //  calloc Call Utility Functions.
    113 //
    114 
    115 /// extractCallocCall - Returns the corresponding CallInst if the instruction
    116 /// is a calloc call.
    117 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
    118 static inline CallInst *extractCallocCall(Value *I,
    119                                           const TargetLibraryInfo *TLI) {
    120   return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
    121 }
    122 
    123 
    124 //===----------------------------------------------------------------------===//
    125 //  free Call Utility Functions.
    126 //
    127 
    128 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
    129 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
    130 
    131 static inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
    132   return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
    133 }
    134 
    135 
    136 //===----------------------------------------------------------------------===//
    137 //  Utility functions to compute size of objects.
    138 //
    139 
    140 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
    141 /// object size in Size if successful, and false otherwise. In this context, by
    142 /// object we mean the region of memory starting at Ptr to the end of the
    143 /// underlying object pointed to by Ptr.
    144 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
    145 /// byval arguments, and global variables.
    146 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *TD,
    147                    const TargetLibraryInfo *TLI, bool RoundToAlign = false);
    148 
    149 /// \brief Compute the size of the underlying object pointed by Ptr. Returns
    150 /// true and the object size in Size if successful, and false otherwise.
    151 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
    152 /// byval arguments, and global variables.
    153 bool getUnderlyingObjectSize(const Value *Ptr, uint64_t &Size,
    154                              const DataLayout *TD, const TargetLibraryInfo *TLI,
    155                              bool RoundToAlign = false);
    156 
    157 
    158 
    159 typedef std::pair<APInt, APInt> SizeOffsetType;
    160 
    161 /// \brief Evaluate the size and offset of an object ponted by a Value*
    162 /// statically. Fails if size or offset are not known at compile time.
    163 class ObjectSizeOffsetVisitor
    164   : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
    165 
    166   typedef DenseMap<const Value*, SizeOffsetType> CacheMapTy;
    167 
    168   const DataLayout *TD;
    169   const TargetLibraryInfo *TLI;
    170   bool RoundToAlign;
    171   unsigned IntTyBits;
    172   APInt Zero;
    173   CacheMapTy CacheMap;
    174 
    175   APInt align(APInt Size, uint64_t Align);
    176 
    177   SizeOffsetType unknown() {
    178     return std::make_pair(APInt(), APInt());
    179   }
    180 
    181 public:
    182   ObjectSizeOffsetVisitor(const DataLayout *TD, const TargetLibraryInfo *TLI,
    183                           LLVMContext &Context, bool RoundToAlign = false);
    184 
    185   SizeOffsetType compute(Value *V);
    186 
    187   bool knownSize(SizeOffsetType &SizeOffset) {
    188     return SizeOffset.first.getBitWidth() > 1;
    189   }
    190 
    191   bool knownOffset(SizeOffsetType &SizeOffset) {
    192     return SizeOffset.second.getBitWidth() > 1;
    193   }
    194 
    195   bool bothKnown(SizeOffsetType &SizeOffset) {
    196     return knownSize(SizeOffset) && knownOffset(SizeOffset);
    197   }
    198 
    199   SizeOffsetType visitAllocaInst(AllocaInst &I);
    200   SizeOffsetType visitArgument(Argument &A);
    201   SizeOffsetType visitCallSite(CallSite CS);
    202   SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
    203   SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
    204   SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
    205   SizeOffsetType visitGEPOperator(GEPOperator &GEP);
    206   SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
    207   SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
    208   SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
    209   SizeOffsetType visitLoadInst(LoadInst &I);
    210   SizeOffsetType visitPHINode(PHINode&);
    211   SizeOffsetType visitSelectInst(SelectInst &I);
    212   SizeOffsetType visitUndefValue(UndefValue&);
    213   SizeOffsetType visitInstruction(Instruction &I);
    214 };
    215 
    216 typedef std::pair<Value*, Value*> SizeOffsetEvalType;
    217 
    218 
    219 /// \brief Evaluate the size and offset of an object ponted by a Value*.
    220 /// May create code to compute the result at run-time.
    221 class ObjectSizeOffsetEvaluator
    222   : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
    223 
    224   typedef IRBuilder<true, TargetFolder> BuilderTy;
    225   typedef std::pair<WeakVH, WeakVH> WeakEvalType;
    226   typedef DenseMap<const Value*, WeakEvalType> CacheMapTy;
    227   typedef SmallPtrSet<const Value*, 8> PtrSetTy;
    228 
    229   const DataLayout *TD;
    230   const TargetLibraryInfo *TLI;
    231   LLVMContext &Context;
    232   BuilderTy Builder;
    233   IntegerType *IntTy;
    234   Value *Zero;
    235   CacheMapTy CacheMap;
    236   PtrSetTy SeenVals;
    237 
    238   SizeOffsetEvalType unknown() {
    239     return std::make_pair((Value*)0, (Value*)0);
    240   }
    241   SizeOffsetEvalType compute_(Value *V);
    242 
    243 public:
    244   ObjectSizeOffsetEvaluator(const DataLayout *TD, const TargetLibraryInfo *TLI,
    245                             LLVMContext &Context);
    246   SizeOffsetEvalType compute(Value *V);
    247 
    248   bool knownSize(SizeOffsetEvalType SizeOffset) {
    249     return SizeOffset.first;
    250   }
    251 
    252   bool knownOffset(SizeOffsetEvalType SizeOffset) {
    253     return SizeOffset.second;
    254   }
    255 
    256   bool anyKnown(SizeOffsetEvalType SizeOffset) {
    257     return knownSize(SizeOffset) || knownOffset(SizeOffset);
    258   }
    259 
    260   bool bothKnown(SizeOffsetEvalType SizeOffset) {
    261     return knownSize(SizeOffset) && knownOffset(SizeOffset);
    262   }
    263 
    264   SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
    265   SizeOffsetEvalType visitCallSite(CallSite CS);
    266   SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
    267   SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
    268   SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
    269   SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
    270   SizeOffsetEvalType visitLoadInst(LoadInst &I);
    271   SizeOffsetEvalType visitPHINode(PHINode &PHI);
    272   SizeOffsetEvalType visitSelectInst(SelectInst &I);
    273   SizeOffsetEvalType visitInstruction(Instruction &I);
    274 };
    275 
    276 } // End llvm namespace
    277 
    278 #endif
    279