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 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 static Value *computeArraySize(const CallInst *CI, const TargetData *TD,
91 bool LookThroughSExt = false) {
95 // The size of the malloc's result type must be known to determine array size.
96 const Type *T = getMallocAllocatedType(CI);
97 if (!T || !T->isSized() || !TD)
100 unsigned ElementSize = TD->getTypeAllocSize(T);
101 if (const StructType *ST = dyn_cast<StructType>(T))
102 ElementSize = TD->getStructLayout(ST)->getSizeInBytes();
104 // If malloc calls' arg can be determined to be a multiple of ElementSize,
105 // return the multiple. Otherwise, return NULL.
106 Value *MallocArg = CI->getOperand(1);
107 Value *Multiple = NULL;
108 APInt Val(TD->getTypeSizeInBits(MallocArg->getType()->getScalarType()), 0);
109 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
110 Val, LookThroughSExt, TD))
116 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
117 /// is a call to malloc whose array size can be determined and the array size
118 /// is not constant 1. Otherwise, return NULL.
119 const CallInst *llvm::isArrayMalloc(const Value *I, const TargetData *TD) {
120 const CallInst *CI = extractMallocCall(I);
121 Value *ArraySize = computeArraySize(CI, TD);
124 ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
127 // CI is a non-array malloc or we can't figure out that it is an array malloc.
131 /// getMallocType - Returns the PointerType resulting from the malloc call.
132 /// The PointerType depends on the number of bitcast uses of the malloc call:
133 /// 0: PointerType is the calls' return type.
134 /// 1: PointerType is the bitcast's result type.
135 /// >1: Unique PointerType cannot be determined, return NULL.
136 const PointerType *llvm::getMallocType(const CallInst *CI) {
137 assert(isMalloc(CI) && "getMallocType and not malloc call");
139 const PointerType *MallocType = NULL;
140 unsigned NumOfBitCastUses = 0;
142 // Determine if CallInst has a bitcast use.
143 for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
145 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
146 MallocType = cast<PointerType>(BCI->getDestTy());
150 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
151 if (NumOfBitCastUses == 1)
154 // Malloc call was not bitcast, so type is the malloc function's return type.
155 if (NumOfBitCastUses == 0)
156 return cast<PointerType>(CI->getType());
158 // Type could not be determined.
162 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
163 /// The Type depends on the number of bitcast uses of the malloc call:
164 /// 0: PointerType is the malloc calls' return type.
165 /// 1: PointerType is the bitcast's result type.
166 /// >1: Unique PointerType cannot be determined, return NULL.
167 const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
168 const PointerType *PT = getMallocType(CI);
169 return PT ? PT->getElementType() : NULL;
172 /// getMallocArraySize - Returns the array size of a malloc call. If the
173 /// argument passed to malloc is a multiple of the size of the malloced type,
174 /// then return that multiple. For non-array mallocs, the multiple is
175 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
177 Value *llvm::getMallocArraySize(CallInst *CI, const TargetData *TD,
178 bool LookThroughSExt) {
179 assert(isMalloc(CI) && "getMallocArraySize and not malloc call");
180 return computeArraySize(CI, TD, LookThroughSExt);
183 //===----------------------------------------------------------------------===//
184 // free Call Utility Functions.
187 /// isFreeCall - Returns true if the the value is a call to the builtin free()
188 bool llvm::isFreeCall(const Value *I) {
189 const CallInst *CI = dyn_cast<CallInst>(I);
192 Function *Callee = CI->getCalledFunction();
193 if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "free")
196 // Check free prototype.
197 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
198 // attribute will exist.
199 const FunctionType *FTy = Callee->getFunctionType();
200 if (!FTy->getReturnType()->isVoidTy())
202 if (FTy->getNumParams() != 1)
204 if (FTy->param_begin()->get() != Type::getInt8PtrTy(Callee->getContext()))