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/ADT/APInt.h"
20 #include "llvm/Analysis/ConstantFolding.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 const Module* M = CI->getParent()->getParent()->getParent();
38 Function *MallocFunc = M->getFunction("malloc");
40 if (CI->getOperand(0) != MallocFunc)
43 // Check malloc prototype.
44 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
45 // attribute will exist.
46 const FunctionType *FTy = MallocFunc->getFunctionType();
47 if (FTy->getNumParams() != 1)
49 if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
50 if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
58 /// extractMallocCall - Returns the corresponding CallInst if the instruction
59 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
60 /// ignore InvokeInst here.
61 const CallInst* llvm::extractMallocCall(const Value* I) {
62 const CallInst *CI = dyn_cast<CallInst>(I);
63 return (isMallocCall(CI)) ? CI : NULL;
66 CallInst* llvm::extractMallocCall(Value* I) {
67 CallInst *CI = dyn_cast<CallInst>(I);
68 return (isMallocCall(CI)) ? CI : NULL;
71 static bool isBitCastOfMallocCall(const BitCastInst* BCI) {
75 return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
78 /// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
79 /// instruction is a bitcast of the result of a malloc call.
80 CallInst* llvm::extractMallocCallFromBitCast(Value* I) {
81 BitCastInst *BCI = dyn_cast<BitCastInst>(I);
82 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
86 const CallInst* llvm::extractMallocCallFromBitCast(const Value* I) {
87 const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
88 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
92 /// isConstantOne - Return true only if val is constant int 1.
93 static bool isConstantOne(Value *val) {
94 return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
97 static Value* isArrayMallocHelper(const CallInst *CI, LLVMContext &Context,
98 const TargetData* TD) {
102 // Type must be known to determine array size.
103 const Type* T = getMallocAllocatedType(CI);
107 Value* MallocArg = CI->getOperand(1);
108 ConstantExpr* CO = dyn_cast<ConstantExpr>(MallocArg);
109 BinaryOperator* BO = dyn_cast<BinaryOperator>(MallocArg);
111 Constant* ElementSize = ConstantExpr::getSizeOf(T);
112 ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
113 MallocArg->getType());
114 Constant *FoldedElementSize =
115 ConstantFoldConstantExpression(cast<ConstantExpr>(ElementSize), Context, TD);
117 // First, check if CI is a non-array malloc.
118 if (CO && ((CO == ElementSize) ||
119 (FoldedElementSize && (CO == FoldedElementSize))))
120 // Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
121 return ConstantInt::get(MallocArg->getType(), 1);
123 // Second, check if CI is an array malloc whose array size can be determined.
124 if (isConstantOne(ElementSize) ||
125 (FoldedElementSize && isConstantOne(FoldedElementSize)))
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 (FoldedElementSize && (Op1 == FoldedElementSize)))
152 // ArraySize * ElementSize
154 if ((Op0 == ElementSize) ||
155 (FoldedElementSize && (Op0 == FoldedElementSize)))
156 // ElementSize * ArraySize
159 if (Opcode == Instruction::Shl) {
160 ConstantInt* Op1CI = dyn_cast<ConstantInt>(Op1);
161 if (!Op1CI) return NULL;
163 APInt Op1Int = Op1CI->getValue();
164 unsigned Op1Width = Op1Int.getBitWidth();
165 // check for overflow
166 if (Op1Int.getActiveBits() > 64 || Op1Int.getZExtValue() > Op1Width)
168 Value* Op1Pow = ConstantInt::get(Context,
169 APInt(Op1Width, 0).set(Op1Int.getZExtValue()));
171 if (Op0 == ElementSize || (FoldedElementSize && Op0 == FoldedElementSize))
172 // ArraySize << log2(ElementSize)
174 if (Op1Pow == ElementSize ||
175 (FoldedElementSize && Op1Pow == FoldedElementSize))
176 // ElementSize << log2(ArraySize)
181 // We could not determine the malloc array size from MallocArg.
185 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
186 /// is a call to malloc whose array size can be determined and the array size
187 /// is not constant 1. Otherwise, return NULL.
188 CallInst* llvm::isArrayMalloc(Value* I, LLVMContext &Context,
189 const TargetData* TD) {
190 CallInst *CI = extractMallocCall(I);
191 Value* ArraySize = isArrayMallocHelper(CI, Context, TD);
194 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
197 // CI is a non-array malloc or we can't figure out that it is an array malloc.
201 const CallInst* llvm::isArrayMalloc(const Value* I, LLVMContext &Context,
202 const TargetData* TD) {
203 const CallInst *CI = extractMallocCall(I);
204 Value* ArraySize = isArrayMallocHelper(CI, Context, TD);
207 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
210 // CI is a non-array malloc or we can't figure out that it is an array malloc.
214 /// getMallocType - Returns the PointerType resulting from the malloc call.
215 /// This PointerType is the result type of the call's only bitcast use.
216 /// If there is no unique bitcast use, then return NULL.
217 const PointerType* llvm::getMallocType(const CallInst* CI) {
218 assert(isMalloc(CI) && "GetMallocType and not malloc call");
220 const BitCastInst* BCI = NULL;
222 // Determine if CallInst has a bitcast use.
223 for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
225 if ((BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++))))
228 // Malloc call has 1 bitcast use and no other uses, so type is the bitcast's
230 if (BCI && CI->hasOneUse())
231 return cast<PointerType>(BCI->getDestTy());
233 // Malloc call was not bitcast, so type is the malloc function's return type.
235 return cast<PointerType>(CI->getType());
237 // Type could not be determined.
241 /// getMallocAllocatedType - Returns the Type allocated by malloc call. This
242 /// Type is the result type of the call's only bitcast use. If there is no
243 /// unique bitcast use, then return NULL.
244 const Type* llvm::getMallocAllocatedType(const CallInst* CI) {
245 const PointerType* PT = getMallocType(CI);
246 return PT ? PT->getElementType() : NULL;
249 /// getMallocArraySize - Returns the array size of a malloc call. If the
250 /// argument passed to malloc is a multiple of the size of the malloced type,
251 /// then return that multiple. For non-array mallocs, the multiple is
252 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
254 Value* llvm::getMallocArraySize(CallInst* CI, LLVMContext &Context,
255 const TargetData* TD) {
256 return isArrayMallocHelper(CI, Context, TD);
259 //===----------------------------------------------------------------------===//
260 // free Call Utility Functions.
263 /// isFreeCall - Returns true if the the value is a call to the builtin free()
264 bool llvm::isFreeCall(const Value* I) {
265 const CallInst *CI = dyn_cast<CallInst>(I);
269 const Module* M = CI->getParent()->getParent()->getParent();
270 Function *FreeFunc = M->getFunction("free");
272 if (CI->getOperand(0) != FreeFunc)
275 // Check free prototype.
276 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
277 // attribute will exist.
278 const FunctionType *FTy = FreeFunc->getFunctionType();
279 if (FTy->getReturnType() != Type::getVoidTy(M->getContext()))
281 if (FTy->getNumParams() != 1)
283 if (FTy->param_begin()->get() != Type::getInt8PtrTy(M->getContext()))