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"
22 //===----------------------------------------------------------------------===//
23 // malloc Call Utility Functions.
26 /// isMalloc - Returns true if the the value is either a malloc call or a
27 /// bitcast of the result of a malloc call.
28 bool llvm::isMalloc(const Value *I) {
29 return extractMallocCall(I) || extractMallocCallFromBitCast(I);
32 static bool isMallocCall(const CallInst *CI) {
36 const Module *M = CI->getParent()->getParent()->getParent();
37 Function *MallocFunc = M->getFunction("malloc");
39 if (CI->getOperand(0) != MallocFunc)
42 // Check malloc prototype.
43 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
44 // attribute will exist.
45 const FunctionType *FTy = MallocFunc->getFunctionType();
46 if (FTy->getNumParams() != 1)
48 if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
49 if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
57 /// extractMallocCall - Returns the corresponding CallInst if the instruction
58 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
59 /// ignore InvokeInst here.
60 const CallInst *llvm::extractMallocCall(const Value *I) {
61 const CallInst *CI = dyn_cast<CallInst>(I);
62 return (isMallocCall(CI)) ? CI : NULL;
65 CallInst *llvm::extractMallocCall(Value *I) {
66 CallInst *CI = dyn_cast<CallInst>(I);
67 return (isMallocCall(CI)) ? CI : NULL;
70 static bool isBitCastOfMallocCall(const BitCastInst *BCI) {
74 return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
77 /// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
78 /// instruction is a bitcast of the result of a malloc call.
79 CallInst *llvm::extractMallocCallFromBitCast(Value *I) {
80 BitCastInst *BCI = dyn_cast<BitCastInst>(I);
81 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
85 const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) {
86 const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
87 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
91 /// isConstantOne - Return true only if val is constant int 1.
92 static bool isConstantOne(Value *val) {
93 return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
96 static Value *isArrayMallocHelper(const CallInst *CI, LLVMContext &Context,
97 const TargetData *TD) {
101 // Type must be known to determine array size.
102 const Type *T = getMallocAllocatedType(CI);
106 Value *MallocArg = CI->getOperand(1);
107 ConstantExpr *CO = dyn_cast<ConstantExpr>(MallocArg);
108 BinaryOperator *BO = dyn_cast<BinaryOperator>(MallocArg);
110 Constant *ElementSize = ConstantExpr::getSizeOf(T);
111 ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
112 MallocArg->getType());
113 Constant *FoldedElementSize =
114 ConstantFoldConstantExpression(cast<ConstantExpr>(ElementSize), Context, TD);
116 // First, check if CI is a non-array malloc.
117 if (CO && ((CO == ElementSize) ||
118 (FoldedElementSize && (CO == FoldedElementSize))))
119 // Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
120 return ConstantInt::get(MallocArg->getType(), 1);
122 // Second, check if CI is an array malloc whose array size can be determined.
123 if (isConstantOne(ElementSize) ||
124 (FoldedElementSize && isConstantOne(FoldedElementSize)))
133 if (CO && ((CO->getOpcode() == Instruction::Mul) ||
134 (CO->getOpcode() == Instruction::Shl))) {
135 Op0 = CO->getOperand(0);
136 Op1 = CO->getOperand(1);
137 Opcode = CO->getOpcode();
139 if (BO && ((BO->getOpcode() == Instruction::Mul) ||
140 (BO->getOpcode() == Instruction::Shl))) {
141 Op0 = BO->getOperand(0);
142 Op1 = BO->getOperand(1);
143 Opcode = BO->getOpcode();
146 // Determine array size if malloc's argument is the product of a mul or shl.
148 if (Opcode == Instruction::Mul) {
149 if ((Op1 == ElementSize) ||
150 (FoldedElementSize && (Op1 == FoldedElementSize)))
151 // ArraySize * ElementSize
153 if ((Op0 == ElementSize) ||
154 (FoldedElementSize && (Op0 == FoldedElementSize)))
155 // ElementSize * ArraySize
158 if (Opcode == Instruction::Shl) {
159 ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1);
160 if (!Op1CI) return NULL;
162 APInt Op1Int = Op1CI->getValue();
163 uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1);
164 Value *Op1Pow = ConstantInt::get(Context,
165 APInt(Op1Int.getBitWidth(), 0).set(BitToSet));
166 if (Op0 == ElementSize || (FoldedElementSize && Op0 == FoldedElementSize))
167 // ArraySize << log2(ElementSize)
169 if (Op1Pow == ElementSize ||
170 (FoldedElementSize && Op1Pow == FoldedElementSize))
171 // ElementSize << log2(ArraySize)
176 // We could not determine the malloc array size from MallocArg.
180 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
181 /// is a call to malloc whose array size can be determined and the array size
182 /// is not constant 1. Otherwise, return NULL.
183 CallInst *llvm::isArrayMalloc(Value *I, LLVMContext &Context,
184 const TargetData *TD) {
185 CallInst *CI = extractMallocCall(I);
186 Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
189 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
192 // CI is a non-array malloc or we can't figure out that it is an array malloc.
196 const CallInst *llvm::isArrayMalloc(const Value *I, LLVMContext &Context,
197 const TargetData *TD) {
198 const CallInst *CI = extractMallocCall(I);
199 Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
202 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
205 // CI is a non-array malloc or we can't figure out that it is an array malloc.
209 /// getMallocType - Returns the PointerType resulting from the malloc call.
210 /// This PointerType is the result type of the call's only bitcast use.
211 /// If there is no unique bitcast use, then return NULL.
212 const PointerType *llvm::getMallocType(const CallInst *CI) {
213 assert(isMalloc(CI) && "GetMallocType and not malloc call");
215 const BitCastInst *BCI = NULL;
217 // Determine if CallInst has a bitcast use.
218 for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
220 if ((BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++))))
223 // Malloc call has 1 bitcast use and no other uses, so type is the bitcast's
225 if (BCI && CI->hasOneUse())
226 return cast<PointerType>(BCI->getDestTy());
228 // Malloc call was not bitcast, so type is the malloc function's return type.
230 return cast<PointerType>(CI->getType());
232 // Type could not be determined.
236 /// getMallocAllocatedType - Returns the Type allocated by malloc call. This
237 /// Type is the result type of the call's only bitcast use. If there is no
238 /// unique bitcast use, then return NULL.
239 const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
240 const PointerType *PT = getMallocType(CI);
241 return PT ? PT->getElementType() : NULL;
244 /// getMallocArraySize - Returns the array size of a malloc call. If the
245 /// argument passed to malloc is a multiple of the size of the malloced type,
246 /// then return that multiple. For non-array mallocs, the multiple is
247 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
249 Value *llvm::getMallocArraySize(CallInst *CI, LLVMContext &Context,
250 const TargetData *TD) {
251 return isArrayMallocHelper(CI, Context, TD);
254 //===----------------------------------------------------------------------===//
255 // free Call Utility Functions.
258 /// isFreeCall - Returns true if the the value is a call to the builtin free()
259 bool llvm::isFreeCall(const Value *I) {
260 const CallInst *CI = dyn_cast<CallInst>(I);
264 const Module *M = CI->getParent()->getParent()->getParent();
265 Function *FreeFunc = M->getFunction("free");
267 if (CI->getOperand(0) != FreeFunc)
270 // Check free prototype.
271 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
272 // attribute will exist.
273 const FunctionType *FTy = FreeFunc->getFunctionType();
274 if (FTy->getReturnType() != Type::getVoidTy(M->getContext()))
276 if (FTy->getNumParams() != 1)
278 if (FTy->param_begin()->get() != Type::getInt8PtrTy(M->getContext()))