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 /// 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.
90 PointerType *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.
97 Type *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.
104 Value *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.
114 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
extractCallocCall(Value * I,const TargetLibraryInfo * TLI)115 static 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()
126 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
127
isFreeCall(Value * I,const TargetLibraryInfo * TLI)128 static 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.
143 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
144 const TargetLibraryInfo *TLI, bool RoundToAlign = false);
145
146 typedef 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.
150 class 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
unknown()162 SizeOffsetType unknown() {
163 return std::make_pair(APInt(), APInt());
164 }
165
166 public:
167 ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
168 LLVMContext &Context, bool RoundToAlign = false);
169
170 SizeOffsetType compute(Value *V);
171
knownSize(SizeOffsetType & SizeOffset)172 bool knownSize(SizeOffsetType &SizeOffset) {
173 return SizeOffset.first.getBitWidth() > 1;
174 }
175
knownOffset(SizeOffsetType & SizeOffset)176 bool knownOffset(SizeOffsetType &SizeOffset) {
177 return SizeOffset.second.getBitWidth() > 1;
178 }
179
bothKnown(SizeOffsetType & SizeOffset)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
203 typedef 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.
208 class 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
unknown()226 SizeOffsetEvalType unknown() {
227 return std::make_pair(nullptr, nullptr);
228 }
229 SizeOffsetEvalType compute_(Value *V);
230
231 public:
232 ObjectSizeOffsetEvaluator(const DataLayout &DL, const TargetLibraryInfo *TLI,
233 LLVMContext &Context, bool RoundToAlign = false);
234 SizeOffsetEvalType compute(Value *V);
235
knownSize(SizeOffsetEvalType SizeOffset)236 bool knownSize(SizeOffsetEvalType SizeOffset) {
237 return SizeOffset.first;
238 }
239
knownOffset(SizeOffsetEvalType SizeOffset)240 bool knownOffset(SizeOffsetEvalType SizeOffset) {
241 return SizeOffset.second;
242 }
243
anyKnown(SizeOffsetEvalType SizeOffset)244 bool anyKnown(SizeOffsetEvalType SizeOffset) {
245 return knownSize(SizeOffset) || knownOffset(SizeOffset);
246 }
247
bothKnown(SizeOffsetEvalType SizeOffset)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