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
27namespace llvm {
28class CallInst;
29class PointerType;
30class DataLayout;
31class TargetLibraryInfo;
32class Type;
33class 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).
39bool 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).
44bool 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).
49bool 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).
54bool 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).
59bool 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).
64bool 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).
69bool 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.
79const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI);
80static inline CallInst *extractMallocCall(Value *I,
81                                          const TargetLibraryInfo *TLI) {
82  return const_cast<CallInst*>(extractMallocCall((const Value*)I, TLI));
83}
84
85/// getMallocType - Returns the PointerType resulting from the malloc call.
86/// The PointerType depends on the number of bitcast uses of the malloc call:
87///   0: PointerType is the malloc calls' return type.
88///   1: PointerType is the bitcast's result type.
89///  >1: Unique PointerType cannot be determined, return NULL.
90PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
91
92/// getMallocAllocatedType - Returns the Type allocated by malloc call.
93/// The Type depends on the number of bitcast uses of the malloc call:
94///   0: PointerType is the malloc calls' return type.
95///   1: PointerType is the bitcast's result type.
96///  >1: Unique PointerType cannot be determined, return NULL.
97Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
98
99/// getMallocArraySize - Returns the array size of a malloc call.  If the
100/// argument passed to malloc is a multiple of the size of the malloced type,
101/// then return that multiple.  For non-array mallocs, the multiple is
102/// constant 1.  Otherwise, return NULL for mallocs whose array size cannot be
103/// determined.
104Value *getMallocArraySize(CallInst *CI, const DataLayout &DL,
105                          const TargetLibraryInfo *TLI,
106                          bool LookThroughSExt = false);
107
108//===----------------------------------------------------------------------===//
109//  calloc Call Utility Functions.
110//
111
112/// extractCallocCall - Returns the corresponding CallInst if the instruction
113/// is a calloc call.
114const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
115static inline CallInst *extractCallocCall(Value *I,
116                                          const TargetLibraryInfo *TLI) {
117  return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
118}
119
120
121//===----------------------------------------------------------------------===//
122//  free Call Utility Functions.
123//
124
125/// isFreeCall - Returns non-null if the value is a call to the builtin free()
126const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
127
128static inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
129  return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
130}
131
132
133//===----------------------------------------------------------------------===//
134//  Utility functions to compute size of objects.
135//
136
137/// \brief Compute the size of the object pointed by Ptr. Returns true and the
138/// object size in Size if successful, and false otherwise. In this context, by
139/// object we mean the region of memory starting at Ptr to the end of the
140/// underlying object pointed to by Ptr.
141/// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
142/// byval arguments, and global variables.
143bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
144                   const TargetLibraryInfo *TLI, bool RoundToAlign = false);
145
146typedef std::pair<APInt, APInt> SizeOffsetType;
147
148/// \brief Evaluate the size and offset of an object pointed to by a Value*
149/// statically. Fails if size or offset are not known at compile time.
150class ObjectSizeOffsetVisitor
151  : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
152
153  const DataLayout &DL;
154  const TargetLibraryInfo *TLI;
155  bool RoundToAlign;
156  unsigned IntTyBits;
157  APInt Zero;
158  SmallPtrSet<Instruction *, 8> SeenInsts;
159
160  APInt align(APInt Size, uint64_t Align);
161
162  SizeOffsetType unknown() {
163    return std::make_pair(APInt(), APInt());
164  }
165
166public:
167  ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
168                          LLVMContext &Context, bool RoundToAlign = false);
169
170  SizeOffsetType compute(Value *V);
171
172  bool knownSize(SizeOffsetType &SizeOffset) {
173    return SizeOffset.first.getBitWidth() > 1;
174  }
175
176  bool knownOffset(SizeOffsetType &SizeOffset) {
177    return SizeOffset.second.getBitWidth() > 1;
178  }
179
180  bool bothKnown(SizeOffsetType &SizeOffset) {
181    return knownSize(SizeOffset) && knownOffset(SizeOffset);
182  }
183
184  // These are "private", except they can't actually be made private. Only
185  // compute() should be used by external users.
186  SizeOffsetType visitAllocaInst(AllocaInst &I);
187  SizeOffsetType visitArgument(Argument &A);
188  SizeOffsetType visitCallSite(CallSite CS);
189  SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
190  SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
191  SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
192  SizeOffsetType visitGEPOperator(GEPOperator &GEP);
193  SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
194  SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
195  SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
196  SizeOffsetType visitLoadInst(LoadInst &I);
197  SizeOffsetType visitPHINode(PHINode&);
198  SizeOffsetType visitSelectInst(SelectInst &I);
199  SizeOffsetType visitUndefValue(UndefValue&);
200  SizeOffsetType visitInstruction(Instruction &I);
201};
202
203typedef std::pair<Value*, Value*> SizeOffsetEvalType;
204
205
206/// \brief Evaluate the size and offset of an object pointed to by a Value*.
207/// May create code to compute the result at run-time.
208class ObjectSizeOffsetEvaluator
209  : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
210
211  typedef IRBuilder<true, TargetFolder> BuilderTy;
212  typedef std::pair<WeakVH, WeakVH> WeakEvalType;
213  typedef DenseMap<const Value*, WeakEvalType> CacheMapTy;
214  typedef SmallPtrSet<const Value*, 8> PtrSetTy;
215
216  const DataLayout &DL;
217  const TargetLibraryInfo *TLI;
218  LLVMContext &Context;
219  BuilderTy Builder;
220  IntegerType *IntTy;
221  Value *Zero;
222  CacheMapTy CacheMap;
223  PtrSetTy SeenVals;
224  bool RoundToAlign;
225
226  SizeOffsetEvalType unknown() {
227    return std::make_pair(nullptr, nullptr);
228  }
229  SizeOffsetEvalType compute_(Value *V);
230
231public:
232  ObjectSizeOffsetEvaluator(const DataLayout &DL, const TargetLibraryInfo *TLI,
233                            LLVMContext &Context, bool RoundToAlign = false);
234  SizeOffsetEvalType compute(Value *V);
235
236  bool knownSize(SizeOffsetEvalType SizeOffset) {
237    return SizeOffset.first;
238  }
239
240  bool knownOffset(SizeOffsetEvalType SizeOffset) {
241    return SizeOffset.second;
242  }
243
244  bool anyKnown(SizeOffsetEvalType SizeOffset) {
245    return knownSize(SizeOffset) || knownOffset(SizeOffset);
246  }
247
248  bool bothKnown(SizeOffsetEvalType SizeOffset) {
249    return knownSize(SizeOffset) && knownOffset(SizeOffset);
250  }
251
252  // The individual instruction visitors should be treated as private.
253  SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
254  SizeOffsetEvalType visitCallSite(CallSite CS);
255  SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
256  SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
257  SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
258  SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
259  SizeOffsetEvalType visitLoadInst(LoadInst &I);
260  SizeOffsetEvalType visitPHINode(PHINode &PHI);
261  SizeOffsetEvalType visitSelectInst(SelectInst &I);
262  SizeOffsetEvalType visitInstruction(Instruction &I);
263};
264
265} // End llvm namespace
266
267#endif
268