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);
extractMallocCall(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);
extractCallocCall(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
isFreeCall(Value * I,const TargetLibraryInfo * TLI)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
unknown()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
knownSize(SizeOffsetType & SizeOffset)181 bool knownSize(SizeOffsetType &SizeOffset) {
182 return SizeOffset.first.getBitWidth() > 1;
183 }
184
knownOffset(SizeOffsetType & SizeOffset)185 bool knownOffset(SizeOffsetType &SizeOffset) {
186 return SizeOffset.second.getBitWidth() > 1;
187 }
188
bothKnown(SizeOffsetType & SizeOffset)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
unknown()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
knownSize(SizeOffsetEvalType SizeOffset)245 bool knownSize(SizeOffsetEvalType SizeOffset) {
246 return SizeOffset.first;
247 }
248
knownOffset(SizeOffsetEvalType SizeOffset)249 bool knownOffset(SizeOffsetEvalType SizeOffset) {
250 return SizeOffset.second;
251 }
252
anyKnown(SizeOffsetEvalType SizeOffset)253 bool anyKnown(SizeOffsetEvalType SizeOffset) {
254 return knownSize(SizeOffset) || knownOffset(SizeOffset);
255 }
256
bothKnown(SizeOffsetEvalType SizeOffset)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