MemoryBuiltins.h revision cee51c48030f37133ad4004d3e5c14d8ebfc91c4 
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
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/// 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.
88const 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.
96PointerType *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.
103Type *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.
110Value *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.
121const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
122static 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()
133const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
134
135static 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.
150bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL,
151                   const TargetLibraryInfo *TLI, bool RoundToAlign = false);
152
153
154
155typedef 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.
159class 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
175public:
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  SizeOffsetType visitAllocaInst(AllocaInst &I);
194  SizeOffsetType visitArgument(Argument &A);
195  SizeOffsetType visitCallSite(CallSite CS);
196  SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
197  SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
198  SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
199  SizeOffsetType visitGEPOperator(GEPOperator &GEP);
200  SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
201  SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
202  SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
203  SizeOffsetType visitLoadInst(LoadInst &I);
204  SizeOffsetType visitPHINode(PHINode&);
205  SizeOffsetType visitSelectInst(SelectInst &I);
206  SizeOffsetType visitUndefValue(UndefValue&);
207  SizeOffsetType visitInstruction(Instruction &I);
208};
209
210typedef std::pair<Value*, Value*> SizeOffsetEvalType;
211
212
213/// \brief Evaluate the size and offset of an object pointed to by a Value*.
214/// May create code to compute the result at run-time.
215class ObjectSizeOffsetEvaluator
216  : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
217
218  typedef IRBuilder<true, TargetFolder> BuilderTy;
219  typedef std::pair<WeakVH, WeakVH> WeakEvalType;
220  typedef DenseMap<const Value*, WeakEvalType> CacheMapTy;
221  typedef SmallPtrSet<const Value*, 8> PtrSetTy;
222
223  const DataLayout *DL;
224  const TargetLibraryInfo *TLI;
225  LLVMContext &Context;
226  BuilderTy Builder;
227  IntegerType *IntTy;
228  Value *Zero;
229  CacheMapTy CacheMap;
230  PtrSetTy SeenVals;
231
232  SizeOffsetEvalType unknown() {
233    return std::make_pair((Value*)0, (Value*)0);
234  }
235  SizeOffsetEvalType compute_(Value *V);
236
237public:
238  ObjectSizeOffsetEvaluator(const DataLayout *DL, const TargetLibraryInfo *TLI,
239                            LLVMContext &Context);
240  SizeOffsetEvalType compute(Value *V);
241
242  bool knownSize(SizeOffsetEvalType SizeOffset) {
243    return SizeOffset.first;
244  }
245
246  bool knownOffset(SizeOffsetEvalType SizeOffset) {
247    return SizeOffset.second;
248  }
249
250  bool anyKnown(SizeOffsetEvalType SizeOffset) {
251    return knownSize(SizeOffset) || knownOffset(SizeOffset);
252  }
253
254  bool bothKnown(SizeOffsetEvalType SizeOffset) {
255    return knownSize(SizeOffset) && knownOffset(SizeOffset);
256  }
257
258  SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
259  SizeOffsetEvalType visitCallSite(CallSite CS);
260  SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
261  SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
262  SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
263  SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
264  SizeOffsetEvalType visitLoadInst(LoadInst &I);
265  SizeOffsetEvalType visitPHINode(PHINode &PHI);
266  SizeOffsetEvalType visitSelectInst(SelectInst &I);
267  SizeOffsetEvalType visitInstruction(Instruction &I);
268};
269
270} // End llvm namespace
271
272#endif
273