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
35enum 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).
44bool 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).
49bool 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).
54bool 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).
59bool 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).
64bool 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.
74const CallInst *extractMallocCall(const Value *I, const TargetLibraryInfo *TLI);
75static 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.
85PointerType *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.
92Type *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.
99Value *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.
109const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
110static 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()
121const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
122
123static 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).
140bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
141                   const TargetLibraryInfo *TLI, bool RoundToAlign = false,
142                   ObjSizeMode Mode = ObjSizeMode::Exact);
143
144typedef 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.
148class 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
161  SizeOffsetType unknown() {
162    return std::make_pair(APInt(), APInt());
163  }
164
165public:
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
172  static bool knownSize(const SizeOffsetType &SizeOffset) {
173    return SizeOffset.first.getBitWidth() > 1;
174  }
175
176  static bool knownOffset(const SizeOffsetType &SizeOffset) {
177    return SizeOffset.second.getBitWidth() > 1;
178  }
179
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
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<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