1 //===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This family of functions identifies calls to builtin functions that allocate
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/MemoryBuiltins.h"
16 #include "llvm/Constants.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/Module.h"
19 #include "llvm/Analysis/ConstantFolding.h"
20 #include "llvm/Target/TargetData.h"
23 //===----------------------------------------------------------------------===//
24 // malloc Call Utility Functions.
27 /// isMalloc - Returns true if the the value is either a malloc call or a
28 /// bitcast of the result of a malloc call.
29 bool llvm::isMalloc(const Value *I) {
30 return extractMallocCall(I) || extractMallocCallFromBitCast(I);
33 static bool isMallocCall(const CallInst *CI) {
37 Function *Callee = CI->getCalledFunction();
38 if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "malloc")
41 // Check malloc prototype.
42 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
43 // attribute will exist.
44 const FunctionType *FTy = Callee->getFunctionType();
45 if (FTy->getNumParams() != 1)
47 if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
48 if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
56 /// extractMallocCall - Returns the corresponding CallInst if the instruction
57 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
58 /// ignore InvokeInst here.
59 const CallInst *llvm::extractMallocCall(const Value *I) {
60 const CallInst *CI = dyn_cast<CallInst>(I);
61 return (isMallocCall(CI)) ? CI : NULL;
64 CallInst *llvm::extractMallocCall(Value *I) {
65 CallInst *CI = dyn_cast<CallInst>(I);
66 return (isMallocCall(CI)) ? CI : NULL;
69 static bool isBitCastOfMallocCall(const BitCastInst *BCI) {
73 return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
76 /// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
77 /// instruction is a bitcast of the result of a malloc call.
78 CallInst *llvm::extractMallocCallFromBitCast(Value *I) {
79 BitCastInst *BCI = dyn_cast<BitCastInst>(I);
80 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
84 const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) {
85 const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
86 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
90 /// isConstantOne - Return true only if val is constant int 1.
91 static bool isConstantOne(Value *val) {
92 return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
95 static Value *isArrayMallocHelper(const CallInst *CI, LLVMContext &Context,
96 const TargetData *TD) {
100 // The size of the malloc's result type must be known to determine array size.
101 const Type *T = getMallocAllocatedType(CI);
102 if (!T || !T->isSized() || !TD)
105 Value *MallocArg = CI->getOperand(1);
106 const Type *ArgType = MallocArg->getType();
107 ConstantExpr *CO = dyn_cast<ConstantExpr>(MallocArg);
108 BinaryOperator *BO = dyn_cast<BinaryOperator>(MallocArg);
110 unsigned ElementSizeInt = TD->getTypeAllocSize(T);
111 if (const StructType *ST = dyn_cast<StructType>(T))
112 ElementSizeInt = TD->getStructLayout(ST)->getSizeInBytes();
113 Constant *ElementSize = ConstantInt::get(ArgType, ElementSizeInt);
115 // First, check if CI is a non-array malloc.
116 if (CO && CO == ElementSize)
117 // Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
118 return ConstantInt::get(ArgType, 1);
120 // Second, check if CI is an array malloc whose array size can be determined.
121 if (isConstantOne(ElementSize))
124 if (ConstantInt *CInt = dyn_cast<ConstantInt>(MallocArg))
125 if (CInt->getZExtValue() % ElementSizeInt == 0)
126 return ConstantInt::get(ArgType, CInt->getZExtValue() / ElementSizeInt);
134 if (CO && ((CO->getOpcode() == Instruction::Mul) ||
135 (CO->getOpcode() == Instruction::Shl))) {
136 Op0 = CO->getOperand(0);
137 Op1 = CO->getOperand(1);
138 Opcode = CO->getOpcode();
140 if (BO && ((BO->getOpcode() == Instruction::Mul) ||
141 (BO->getOpcode() == Instruction::Shl))) {
142 Op0 = BO->getOperand(0);
143 Op1 = BO->getOperand(1);
144 Opcode = BO->getOpcode();
147 // Determine array size if malloc's argument is the product of a mul or shl.
149 if (Opcode == Instruction::Mul) {
150 if (Op1 == ElementSize)
151 // ArraySize * ElementSize
153 if (Op0 == ElementSize)
154 // ElementSize * ArraySize
157 if (Opcode == Instruction::Shl) {
158 ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1);
159 if (!Op1CI) return NULL;
161 APInt Op1Int = Op1CI->getValue();
162 uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1);
163 Value *Op1Pow = ConstantInt::get(Context,
164 APInt(Op1Int.getBitWidth(), 0).set(BitToSet));
165 if (Op0 == ElementSize)
166 // ArraySize << log2(ElementSize)
168 if (Op1Pow == ElementSize)
169 // ElementSize << log2(ArraySize)
174 // We could not determine the malloc array size from MallocArg.
178 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
179 /// is a call to malloc whose array size can be determined and the array size
180 /// is not constant 1. Otherwise, return NULL.
181 CallInst *llvm::isArrayMalloc(Value *I, LLVMContext &Context,
182 const TargetData *TD) {
183 CallInst *CI = extractMallocCall(I);
184 Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
187 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
190 // CI is a non-array malloc or we can't figure out that it is an array malloc.
194 const CallInst *llvm::isArrayMalloc(const Value *I, LLVMContext &Context,
195 const TargetData *TD) {
196 const CallInst *CI = extractMallocCall(I);
197 Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
200 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
203 // CI is a non-array malloc or we can't figure out that it is an array malloc.
207 /// getMallocType - Returns the PointerType resulting from the malloc call.
208 /// The PointerType depends on the number of bitcast uses of the malloc call:
209 /// 0: PointerType is the calls' return type.
210 /// 1: PointerType is the bitcast's result type.
211 /// >1: Unique PointerType cannot be determined, return NULL.
212 const PointerType *llvm::getMallocType(const CallInst *CI) {
213 assert(isMalloc(CI) && "GetMallocType and not malloc call");
215 const PointerType *MallocType = NULL;
216 unsigned NumOfBitCastUses = 0;
218 // Determine if CallInst has a bitcast use.
219 for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
221 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
222 MallocType = cast<PointerType>(BCI->getDestTy());
226 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
227 if (NumOfBitCastUses == 1)
230 // Malloc call was not bitcast, so type is the malloc function's return type.
231 if (NumOfBitCastUses == 0)
232 return cast<PointerType>(CI->getType());
234 // Type could not be determined.
238 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
239 /// The Type depends on the number of bitcast uses of the malloc call:
240 /// 0: PointerType is the malloc calls' return type.
241 /// 1: PointerType is the bitcast's result type.
242 /// >1: Unique PointerType cannot be determined, return NULL.
243 const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
244 const PointerType *PT = getMallocType(CI);
245 return PT ? PT->getElementType() : NULL;
248 /// getMallocArraySize - Returns the array size of a malloc call. If the
249 /// argument passed to malloc is a multiple of the size of the malloced type,
250 /// then return that multiple. For non-array mallocs, the multiple is
251 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
253 Value *llvm::getMallocArraySize(CallInst *CI, LLVMContext &Context,
254 const TargetData *TD) {
255 return isArrayMallocHelper(CI, Context, TD);
258 //===----------------------------------------------------------------------===//
259 // free Call Utility Functions.
262 /// isFreeCall - Returns true if the the value is a call to the builtin free()
263 bool llvm::isFreeCall(const Value *I) {
264 const CallInst *CI = dyn_cast<CallInst>(I);
267 Function *Callee = CI->getCalledFunction();
268 if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "free")
271 // Check free prototype.
272 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
273 // attribute will exist.
274 const FunctionType *FTy = Callee->getFunctionType();
275 if (!FTy->getReturnType()->isVoidTy())
277 if (FTy->getNumParams() != 1)
279 if (FTy->param_begin()->get() != Type::getInt8PtrTy(Callee->getContext()))