include/llvm/Analysis/MemoryBuiltins.h

   1 //==- llvm/Analysis/MemoryBuiltins.h - Calls to memory builtins --*- C++ -*-==//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This family of functions identifies calls to builtin functions that allocate
  10 // or free memory.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_ANALYSIS_MEMORYBUILTINS_H
  15 #define LLVM_ANALYSIS_MEMORYBUILTINS_H
  16
  17 #include "llvm/ADT/APInt.h"
  18 #include "llvm/ADT/DenseMap.h"
  19 #include "llvm/ADT/SmallPtrSet.h"
  20 #include "llvm/Analysis/TargetFolder.h"
  21 #include "llvm/Analysis/TargetLibraryInfo.h"
  22 #include "llvm/IR/CallSite.h"
  23 #include "llvm/IR/IRBuilder.h"
  24 #include "llvm/IR/InstVisitor.h"
  25 #include "llvm/IR/ValueHandle.h"
  26 #include <cstdint>
  27 #include <utility>
  28
  29 namespace llvm {
  30
  31 class AllocaInst;
  32 class Argument;
  33 class CallInst;
  34 class ConstantInt;
  35 class ConstantPointerNull;
  36 class DataLayout;
  37 class ExtractElementInst;
  38 class ExtractValueInst;
  39 class GEPOperator;
  40 class GlobalAlias;
  41 class GlobalVariable;
  42 class Instruction;
  43 class IntegerType;
  44 class IntrinsicInst;
  45 class IntToPtrInst;
  46 class LLVMContext;
  47 class LoadInst;
  48 class PHINode;
  49 class PointerType;
  50 class SelectInst;
  51 class TargetLibraryInfo;
  52 class Type;
  53 class UndefValue;
  54 class Value;
  55
  56 /// Tests if a value is a call or invoke to a library function that
  57 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
  58 /// like).
  59 bool isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
  60                     bool LookThroughBitCast = false);
  61 bool isAllocationFn(const Value *V,
  62                     function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
  63                     bool LookThroughBitCast = false);
  64
  65 /// Tests if a value is a call or invoke to a function that returns a
  66 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
  67 bool isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
  68                  bool LookThroughBitCast = false);
  69
  70 /// Tests if a value is a call or invoke to a library function that
  71 /// allocates uninitialized memory (such as malloc).
  72 bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
  73                     bool LookThroughBitCast = false);
  74 bool isMallocLikeFn(const Value *V,
  75                     function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
  76                     bool LookThroughBitCast = false);
  77
  78 /// Tests if a value is a call or invoke to a library function that
  79 /// allocates zero-filled memory (such as calloc).
  80 bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
  81                     bool LookThroughBitCast = false);
  82
  83 /// Tests if a value is a call or invoke to a library function that
  84 /// allocates memory similar to malloc or calloc.
  85 bool isMallocOrCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
  86                             bool LookThroughBitCast = false);
  87
  88 /// Tests if a value is a call or invoke to a library function that
  89 /// allocates memory (either malloc, calloc, or strdup like).
  90 bool isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
  91                    bool LookThroughBitCast = false);
  92
  93 /// Tests if a value is a call or invoke to a library function that
  94 /// reallocates memory (e.g., realloc).
  95 bool isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
  96                      bool LookThroughBitCast = false);
  97
  98 /// Tests if a function is a call or invoke to a library function that
  99 /// reallocates memory (e.g., realloc).
 100 bool isReallocLikeFn(const Function *F, const TargetLibraryInfo *TLI);
 101
 102 /// Tests if a value is a call or invoke to a library function that
 103 /// allocates memory and throws if an allocation failed (e.g., new).
 104 bool isOpNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
 105                      bool LookThroughBitCast = false);
 106
 107 //===----------------------------------------------------------------------===//
 108 //  malloc Call Utility Functions.
 109 //
 110
 111 /// extractMallocCall - Returns the corresponding CallInst if the instruction
 112 /// is a malloc call.  Since CallInst::CreateMalloc() only creates calls, we
 113 /// ignore InvokeInst here.
 114 const CallInst *
 115 extractMallocCall(const Value *I,
 116                   function_ref<const TargetLibraryInfo &(Function &)> GetTLI);
 117 inline CallInst *
 118 extractMallocCall(Value *I,
 119                   function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
 120   return const_cast<CallInst *>(extractMallocCall((const Value *)I, GetTLI));
 121 }
 122
 123 /// getMallocType - Returns the PointerType resulting from the malloc call.
 124 /// The PointerType depends on the number of bitcast uses of the malloc call:
 125 ///   0: PointerType is the malloc calls' return type.
 126 ///   1: PointerType is the bitcast's result type.
 127 ///  >1: Unique PointerType cannot be determined, return NULL.
 128 PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
 129
 130 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
 131 /// The Type depends on the number of bitcast uses of the malloc call:
 132 ///   0: PointerType is the malloc calls' return type.
 133 ///   1: PointerType is the bitcast's result type.
 134 ///  >1: Unique PointerType cannot be determined, return NULL.
 135 Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
 136
 137 /// getMallocArraySize - Returns the array size of a malloc call.  If the
 138 /// argument passed to malloc is a multiple of the size of the malloced type,
 139 /// then return that multiple.  For non-array mallocs, the multiple is
 140 /// constant 1.  Otherwise, return NULL for mallocs whose array size cannot be
 141 /// determined.
 142 Value *getMallocArraySize(CallInst *CI, const DataLayout &DL,
 143                           const TargetLibraryInfo *TLI,
 144                           bool LookThroughSExt = false);
 145
 146 //===----------------------------------------------------------------------===//
 147 //  calloc Call Utility Functions.
 148 //
 149
 150 /// extractCallocCall - Returns the corresponding CallInst if the instruction
 151 /// is a calloc call.
 152 const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
 153 inline CallInst *extractCallocCall(Value *I, const TargetLibraryInfo *TLI) {
 154   return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
 155 }
 156
 157
 158 //===----------------------------------------------------------------------===//
 159 //  free Call Utility Functions.
 160 //
 161
 162 /// isLibFreeFunction - Returns true if the function is a builtin free()
 163 bool isLibFreeFunction(const Function *F, const LibFunc TLIFn);
 164
 165 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
 166 const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
 167
 168 inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
 169   return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
 170 }
 171
 172 //===----------------------------------------------------------------------===//
 173 //  Utility functions to compute size of objects.
 174 //
 175
 176 /// Various options to control the behavior of getObjectSize.
 177 struct ObjectSizeOpts {
 178   /// Controls how we handle conditional statements with unknown conditions.
 179   enum class Mode : uint8_t {
 180     /// Fail to evaluate an unknown condition.
 181     Exact,
 182     /// Evaluate all branches of an unknown condition. If all evaluations
 183     /// succeed, pick the minimum size.
 184     Min,
 185     /// Same as Min, except we pick the maximum size of all of the branches.
 186     Max
 187   };
 188
 189   /// How we want to evaluate this object's size.
 190   Mode EvalMode = Mode::Exact;
 191   /// Whether to round the result up to the alignment of allocas, byval
 192   /// arguments, and global variables.
 193   bool RoundToAlign = false;
 194   /// If this is true, null pointers in address space 0 will be treated as
 195   /// though they can't be evaluated. Otherwise, null is always considered to
 196   /// point to a 0 byte region of memory.
 197   bool NullIsUnknownSize = false;
 198 };
 199
 200 /// Compute the size of the object pointed by Ptr. Returns true and the
 201 /// object size in Size if successful, and false otherwise. In this context, by
 202 /// object we mean the region of memory starting at Ptr to the end of the
 203 /// underlying object pointed to by Ptr.
 204 bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
 205                    const TargetLibraryInfo *TLI, ObjectSizeOpts Opts = {});
 206
 207 /// Try to turn a call to \@llvm.objectsize into an integer value of the given
 208 /// Type. Returns null on failure. If MustSucceed is true, this function will
 209 /// not return null, and may return conservative values governed by the second
 210 /// argument of the call to objectsize.
 211 Value *lowerObjectSizeCall(IntrinsicInst *ObjectSize, const DataLayout &DL,
 212                            const TargetLibraryInfo *TLI, bool MustSucceed);
 213
 214
 215
 216 using SizeOffsetType = std::pair<APInt, APInt>;
 217
 218 /// Evaluate the size and offset of an object pointed to by a Value*
 219 /// statically. Fails if size or offset are not known at compile time.
 220 class ObjectSizeOffsetVisitor
 221   : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
 222   const DataLayout &DL;
 223   const TargetLibraryInfo *TLI;
 224   ObjectSizeOpts Options;
 225   unsigned IntTyBits;
 226   APInt Zero;
 227   SmallPtrSet<Instruction *, 8> SeenInsts;
 228
 229   APInt align(APInt Size, uint64_t Align);
 230
 231   SizeOffsetType unknown() {
 232     return std::make_pair(APInt(), APInt());
 233   }
 234
 235 public:
 236   ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
 237                           LLVMContext &Context, ObjectSizeOpts Options = {});
 238
 239   SizeOffsetType compute(Value *V);
 240
 241   static bool knownSize(const SizeOffsetType &SizeOffset) {
 242     return SizeOffset.first.getBitWidth() > 1;
 243   }
 244
 245   static bool knownOffset(const SizeOffsetType &SizeOffset) {
 246     return SizeOffset.second.getBitWidth() > 1;
 247   }
 248
 249   static bool bothKnown(const SizeOffsetType &SizeOffset) {
 250     return knownSize(SizeOffset) && knownOffset(SizeOffset);
 251   }
 252
 253   // These are "private", except they can't actually be made private. Only
 254   // compute() should be used by external users.
 255   SizeOffsetType visitAllocaInst(AllocaInst &I);
 256   SizeOffsetType visitArgument(Argument &A);
 257   SizeOffsetType visitCallSite(CallSite CS);
 258   SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
 259   SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
 260   SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
 261   SizeOffsetType visitGEPOperator(GEPOperator &GEP);
 262   SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
 263   SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
 264   SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
 265   SizeOffsetType visitLoadInst(LoadInst &I);
 266   SizeOffsetType visitPHINode(PHINode&);
 267   SizeOffsetType visitSelectInst(SelectInst &I);
 268   SizeOffsetType visitUndefValue(UndefValue&);
 269   SizeOffsetType visitInstruction(Instruction &I);
 270
 271 private:
 272   bool CheckedZextOrTrunc(APInt &I);
 273 };
 274
 275 using SizeOffsetEvalType = std::pair<Value *, Value *>;
 276
 277 /// Evaluate the size and offset of an object pointed to by a Value*.
 278 /// May create code to compute the result at run-time.
 279 class ObjectSizeOffsetEvaluator
 280   : public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
 281   using BuilderTy = IRBuilder<TargetFolder, IRBuilderCallbackInserter>;
 282   using WeakEvalType = std::pair<WeakTrackingVH, WeakTrackingVH>;
 283   using CacheMapTy = DenseMap<const Value *, WeakEvalType>;
 284   using PtrSetTy = SmallPtrSet<const Value *, 8>;
 285
 286   const DataLayout &DL;
 287   const TargetLibraryInfo *TLI;
 288   LLVMContext &Context;
 289   BuilderTy Builder;
 290   IntegerType *IntTy;
 291   Value *Zero;
 292   CacheMapTy CacheMap;
 293   PtrSetTy SeenVals;
 294   ObjectSizeOpts EvalOpts;
 295   SmallPtrSet<Instruction *, 8> InsertedInstructions;
 296
 297   SizeOffsetEvalType compute_(Value *V);
 298
 299 public:
 300   static SizeOffsetEvalType unknown() {
 301     return std::make_pair(nullptr, nullptr);
 302   }
 303
 304   ObjectSizeOffsetEvaluator(const DataLayout &DL, const TargetLibraryInfo *TLI,
 305                             LLVMContext &Context, ObjectSizeOpts EvalOpts = {});
 306
 307   SizeOffsetEvalType compute(Value *V);
 308
 309   bool knownSize(SizeOffsetEvalType SizeOffset) {
 310     return SizeOffset.first;
 311   }
 312
 313   bool knownOffset(SizeOffsetEvalType SizeOffset) {
 314     return SizeOffset.second;
 315   }
 316
 317   bool anyKnown(SizeOffsetEvalType SizeOffset) {
 318     return knownSize(SizeOffset) || knownOffset(SizeOffset);
 319   }
 320
 321   bool bothKnown(SizeOffsetEvalType SizeOffset) {
 322     return knownSize(SizeOffset) && knownOffset(SizeOffset);
 323   }
 324
 325   // The individual instruction visitors should be treated as private.
 326   SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
 327   SizeOffsetEvalType visitCallSite(CallSite CS);
 328   SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
 329   SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
 330   SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
 331   SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
 332   SizeOffsetEvalType visitLoadInst(LoadInst &I);
 333   SizeOffsetEvalType visitPHINode(PHINode &PHI);
 334   SizeOffsetEvalType visitSelectInst(SelectInst &I);
 335   SizeOffsetEvalType visitInstruction(Instruction &I);
 336 };
 337
 338 } // end namespace llvm
 339
 340 #endif // LLVM_ANALYSIS_MEMORYBUILTINS_H