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 enum class ObjSizeMode {
36 Exact = 0,
37 Min = 1,
38 Max = 2
39 };
40
41 /// \brief Tests if a value is a call or invoke to a library function that
42 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
43 /// like).
44 bool isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
45 bool LookThroughBitCast = false);
46
47 /// \brief Tests if a value is a call or invoke to a function that returns a
48 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
49 bool isNoAliasFn(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 uninitialized memory (such as malloc).
54 bool isMallocLikeFn(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 zero-filled memory (such as calloc).
59 bool isCallocLikeFn(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 /// allocates memory (either malloc, calloc, or strdup like).
64 bool isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
65 bool LookThroughBitCast = false);
66
67 //===----------------------------------------------------------------------===//
68 // malloc Call Utility Functions.
69 //
70
71 /// extractMallocCall - Returns the corresponding CallInst if the instruction
72 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
73 /// ignore InvokeInst here.
74 const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI);
extractMallocCall(Value * I,const TargetLibraryInfo * TLI)75 static inline CallInst *extractMallocCall(Value *I,
76 const TargetLibraryInfo *TLI) {
77 return const_cast<CallInst*>(extractMallocCall((const Value*)I, TLI));
78 }
79
80 /// getMallocType - Returns the PointerType resulting from the malloc call.
81 /// The PointerType depends on the number of bitcast uses of the malloc call:
82 /// 0: PointerType is the malloc calls' return type.
83 /// 1: PointerType is the bitcast's result type.
84 /// >1: Unique PointerType cannot be determined, return NULL.
85 PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
86
87 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
88 /// The Type 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 Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
93
94 /// getMallocArraySize - Returns the array size of a malloc call. If the
95 /// argument passed to malloc is a multiple of the size of the malloced type,
96 /// then return that multiple. For non-array mallocs, the multiple is
97 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
98 /// determined.
99 Value *getMallocArraySize(CallInst *CI, const DataLayout &DL,
100 const TargetLibraryInfo *TLI,
101 bool LookThroughSExt = false);
102
103 //===----------------------------------------------------------------------===//
104 // calloc Call Utility Functions.
105 //
106
107 /// extractCallocCall - Returns the corresponding CallInst if the instruction
108 /// is a calloc call.
109 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
extractCallocCall(Value * I,const TargetLibraryInfo * TLI)110 static inline CallInst *extractCallocCall(Value *I,
111 const TargetLibraryInfo *TLI) {
112 return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
113 }
114
115
116 //===----------------------------------------------------------------------===//
117 // free Call Utility Functions.
118 //
119
120 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
121 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
122
isFreeCall(Value * I,const TargetLibraryInfo * TLI)123 static inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
124 return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
125 }
126
127
128 //===----------------------------------------------------------------------===//
129 // Utility functions to compute size of objects.
130 //
131
132 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
133 /// object size in Size if successful, and false otherwise. In this context, by
134 /// object we mean the region of memory starting at Ptr to the end of the
135 /// underlying object pointed to by Ptr.
136 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
137 /// byval arguments, and global variables.
138 /// If Mode is Min or Max the size will be evaluated even if it depends on
139 /// a condition and corresponding value will be returned (min or max).
140 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
141 const TargetLibraryInfo *TLI, bool RoundToAlign = false,
142 ObjSizeMode Mode = ObjSizeMode::Exact);
143
144 typedef std::pair<APInt, APInt> SizeOffsetType;
145
146 /// \brief Evaluate the size and offset of an object pointed to by a Value*
147 /// statically. Fails if size or offset are not known at compile time.
148 class ObjectSizeOffsetVisitor
149 : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
150
151 const DataLayout &DL;
152 const TargetLibraryInfo *TLI;
153 bool RoundToAlign;
154 ObjSizeMode Mode;
155 unsigned IntTyBits;
156 APInt Zero;
157 SmallPtrSet<Instruction *, 8> SeenInsts;
158
159 APInt align(APInt Size, uint64_t Align);
160
unknown()161 SizeOffsetType unknown() {
162 return std::make_pair(APInt(), APInt());
163 }
164
165 public:
166 ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
167 LLVMContext &Context, bool RoundToAlign = false,
168 ObjSizeMode Mode = ObjSizeMode::Exact);
169
170 SizeOffsetType compute(Value *V);
171
knownSize(const SizeOffsetType & SizeOffset)172 static bool knownSize(const SizeOffsetType &SizeOffset) {
173 return SizeOffset.first.getBitWidth() > 1;
174 }
175
knownOffset(const SizeOffsetType & SizeOffset)176 static bool knownOffset(const SizeOffsetType &SizeOffset) {
177 return SizeOffset.second.getBitWidth() > 1;
178 }
179
bothKnown(const SizeOffsetType & SizeOffset)180 static bool bothKnown(const 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<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