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/ValueTracking.h"
20 #include "llvm/Target/TargetData.h"
23 //===----------------------------------------------------------------------===//
24 // malloc Call Utility Functions.
27 /// isMalloc - Returns true if 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())
40 if (Callee->getName() != "malloc" &&
41 Callee->getName() != "_Znwj" && // operator new(unsigned int)
42 Callee->getName() != "_Znwm" && // operator new(unsigned long)
43 Callee->getName() != "_Znaj" && // operator new[](unsigned int)
44 Callee->getName() != "_Znam") // operator new[](unsigned long)
47 // Check malloc prototype.
48 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
49 // attribute will exist.
50 const FunctionType *FTy = Callee->getFunctionType();
51 if (FTy->getNumParams() != 1)
53 if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
54 if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
62 /// extractMallocCall - Returns the corresponding CallInst if the instruction
63 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
64 /// ignore InvokeInst here.
65 const CallInst *llvm::extractMallocCall(const Value *I) {
66 const CallInst *CI = dyn_cast<CallInst>(I);
67 return (isMallocCall(CI)) ? CI : NULL;
70 CallInst *llvm::extractMallocCall(Value *I) {
71 CallInst *CI = dyn_cast<CallInst>(I);
72 return (isMallocCall(CI)) ? CI : NULL;
75 static bool isBitCastOfMallocCall(const BitCastInst *BCI) {
79 return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
82 /// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
83 /// instruction is a bitcast of the result of a malloc call.
84 CallInst *llvm::extractMallocCallFromBitCast(Value *I) {
85 BitCastInst *BCI = dyn_cast<BitCastInst>(I);
86 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
90 const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) {
91 const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
92 return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
96 static Value *computeArraySize(const CallInst *CI, const TargetData *TD,
97 bool LookThroughSExt = false) {
101 // The size of the malloc's result type must be known to determine array size.
102 const Type *T = getMallocAllocatedType(CI);
103 if (!T || !T->isSized() || !TD)
106 unsigned ElementSize = TD->getTypeAllocSize(T);
107 if (const StructType *ST = dyn_cast<StructType>(T))
108 ElementSize = TD->getStructLayout(ST)->getSizeInBytes();
110 // If malloc call's arg can be determined to be a multiple of ElementSize,
111 // return the multiple. Otherwise, return NULL.
112 Value *MallocArg = CI->getArgOperand(0);
113 Value *Multiple = NULL;
114 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
121 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
122 /// is a call to malloc whose array size can be determined and the array size
123 /// is not constant 1. Otherwise, return NULL.
124 const CallInst *llvm::isArrayMalloc(const Value *I, const TargetData *TD) {
125 const CallInst *CI = extractMallocCall(I);
126 Value *ArraySize = computeArraySize(CI, TD);
129 ArraySize != ConstantInt::get(CI->getArgOperand(0)->getType(), 1))
132 // CI is a non-array malloc or we can't figure out that it is an array malloc.
136 /// getMallocType - Returns the PointerType resulting from the malloc call.
137 /// The PointerType depends on the number of bitcast uses of the malloc call:
138 /// 0: PointerType is the calls' return type.
139 /// 1: PointerType is the bitcast's result type.
140 /// >1: Unique PointerType cannot be determined, return NULL.
141 const PointerType *llvm::getMallocType(const CallInst *CI) {
142 assert(isMalloc(CI) && "getMallocType and not malloc call");
144 const PointerType *MallocType = NULL;
145 unsigned NumOfBitCastUses = 0;
147 // Determine if CallInst has a bitcast use.
148 for (Value::const_use_iterator UI = CI->use_begin(), E = CI->use_end();
150 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
151 MallocType = cast<PointerType>(BCI->getDestTy());
155 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
156 if (NumOfBitCastUses == 1)
159 // Malloc call was not bitcast, so type is the malloc function's return type.
160 if (NumOfBitCastUses == 0)
161 return cast<PointerType>(CI->getType());
163 // Type could not be determined.
167 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
168 /// The Type depends on the number of bitcast uses of the malloc call:
169 /// 0: PointerType is the malloc calls' return type.
170 /// 1: PointerType is the bitcast's result type.
171 /// >1: Unique PointerType cannot be determined, return NULL.
172 const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
173 const PointerType *PT = getMallocType(CI);
174 return PT ? PT->getElementType() : NULL;
177 /// getMallocArraySize - Returns the array size of a malloc call. If the
178 /// argument passed to malloc is a multiple of the size of the malloced type,
179 /// then return that multiple. For non-array mallocs, the multiple is
180 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
182 Value *llvm::getMallocArraySize(CallInst *CI, const TargetData *TD,
183 bool LookThroughSExt) {
184 assert(isMalloc(CI) && "getMallocArraySize and not malloc call");
185 return computeArraySize(CI, TD, LookThroughSExt);
188 //===----------------------------------------------------------------------===//
189 // free Call Utility Functions.
192 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
193 const CallInst *llvm::isFreeCall(const Value *I) {
194 const CallInst *CI = dyn_cast<CallInst>(I);
197 Function *Callee = CI->getCalledFunction();
198 if (Callee == 0 || !Callee->isDeclaration())
201 if (Callee->getName() != "free" &&
202 Callee->getName() != "_ZdlPv" && // operator delete(void*)
203 Callee->getName() != "_ZdaPv") // operator delete[](void*)
206 // Check free prototype.
207 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
208 // attribute will exist.
209 const FunctionType *FTy = Callee->getFunctionType();
210 if (!FTy->getReturnType()->isVoidTy())
212 if (FTy->getNumParams() != 1)
214 if (FTy->param_begin()->get() != Type::getInt8PtrTy(Callee->getContext()))