1 //===- RaiseAllocations.cpp - Convert @malloc & @free calls to insts ------===//
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 file defines the RaiseAllocations pass which convert malloc and free
11 // calls to malloc and free instructions.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "raiseallocs"
16 #include "llvm/Transforms/IPO.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Module.h"
20 #include "llvm/Instructions.h"
21 #include "llvm/Pass.h"
22 #include "llvm/Support/CallSite.h"
23 #include "llvm/Support/Compiler.h"
24 #include "llvm/ADT/Statistic.h"
28 STATISTIC(NumRaised, "Number of allocations raised");
31 // RaiseAllocations - Turn @malloc and @free calls into the appropriate
34 class VISIBILITY_HIDDEN RaiseAllocations : public ModulePass {
35 Function *MallocFunc; // Functions in the module we are processing
36 Function *FreeFunc; // Initialized by doPassInitializationVirt
38 static char ID; // Pass identification, replacement for typeid
40 : ModulePass(&ID), MallocFunc(0), FreeFunc(0) {}
42 // doPassInitialization - For the raise allocations pass, this finds a
43 // declaration for malloc and free if they exist.
45 void doInitialization(Module &M);
47 // run - This method does the actual work of converting instructions over.
49 bool runOnModule(Module &M);
51 } // end anonymous namespace
53 char RaiseAllocations::ID = 0;
54 static RegisterPass<RaiseAllocations>
55 X("raiseallocs", "Raise allocations from calls to instructions");
57 // createRaiseAllocationsPass - The interface to this file...
58 ModulePass *llvm::createRaiseAllocationsPass() {
59 return new RaiseAllocations();
63 // If the module has a symbol table, they might be referring to the malloc and
64 // free functions. If this is the case, grab the method pointers that the
67 // Lookup @malloc and @free in the symbol table, for later use. If they don't
68 // exist, or are not external, we do not worry about converting calls to that
69 // function into the appropriate instruction.
71 void RaiseAllocations::doInitialization(Module &M) {
73 // Get Malloc and free prototypes if they exist!
74 MallocFunc = M.getFunction("malloc");
76 const FunctionType* TyWeHave = MallocFunc->getFunctionType();
78 // Get the expected prototype for malloc
79 const FunctionType *Malloc1Type =
80 FunctionType::get(PointerType::getUnqual(Type::Int8Ty),
81 std::vector<const Type*>(1, Type::Int64Ty), false);
83 // Chck to see if we got the expected malloc
84 if (TyWeHave != Malloc1Type) {
85 // Check to see if the prototype is wrong, giving us i8*(i32) * malloc
86 // This handles the common declaration of: 'void *malloc(unsigned);'
87 const FunctionType *Malloc2Type =
88 FunctionType::get(PointerType::getUnqual(Type::Int8Ty),
89 std::vector<const Type*>(1, Type::Int32Ty), false);
90 if (TyWeHave != Malloc2Type) {
91 // Check to see if the prototype is missing, giving us
93 // This handles the common declaration of: 'void *malloc();'
94 const FunctionType *Malloc3Type =
95 FunctionType::get(PointerType::getUnqual(Type::Int8Ty), true);
96 if (TyWeHave != Malloc3Type)
103 FreeFunc = M.getFunction("free");
105 const FunctionType* TyWeHave = FreeFunc->getFunctionType();
107 // Get the expected prototype for void free(i8*)
108 const FunctionType *Free1Type = FunctionType::get(Type::VoidTy,
109 std::vector<const Type*>(1, PointerType::getUnqual(Type::Int8Ty)), false);
111 if (TyWeHave != Free1Type) {
112 // Check to see if the prototype was forgotten, giving us
114 // This handles the common forward declaration of: 'void free();'
115 const FunctionType* Free2Type = FunctionType::get(Type::VoidTy, true);
117 if (TyWeHave != Free2Type) {
118 // One last try, check to see if we can find free as
119 // int (...)* free. This handles the case where NOTHING was declared.
120 const FunctionType* Free3Type = FunctionType::get(Type::Int32Ty, true);
122 if (TyWeHave != Free3Type) {
130 // Don't mess with locally defined versions of these functions...
131 if (MallocFunc && !MallocFunc->isDeclaration()) MallocFunc = 0;
132 if (FreeFunc && !FreeFunc->isDeclaration()) FreeFunc = 0;
135 // run - Transform calls into instructions...
137 bool RaiseAllocations::runOnModule(Module &M) {
138 // Find the malloc/free prototypes...
141 bool Changed = false;
143 // First, process all of the malloc calls...
145 std::vector<User*> Users(MallocFunc->use_begin(), MallocFunc->use_end());
146 std::vector<Value*> EqPointers; // Values equal to MallocFunc
147 while (!Users.empty()) {
148 User *U = Users.back();
151 if (Instruction *I = dyn_cast<Instruction>(U)) {
152 CallSite CS = CallSite::get(I);
153 if (CS.getInstruction() && !CS.arg_empty() &&
154 (CS.getCalledFunction() == MallocFunc ||
155 std::find(EqPointers.begin(), EqPointers.end(),
156 CS.getCalledValue()) != EqPointers.end())) {
158 Value *Source = *CS.arg_begin();
160 // If no prototype was provided for malloc, we may need to cast the
162 if (Source->getType() != Type::Int32Ty)
164 CastInst::CreateIntegerCast(Source, Type::Int32Ty, false/*ZExt*/,
167 MallocInst *MI = new MallocInst(Type::Int8Ty, Source, "", I);
169 I->replaceAllUsesWith(MI);
171 // If the old instruction was an invoke, add an unconditional branch
172 // before the invoke, which will become the new terminator.
173 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
174 BranchInst::Create(II->getNormalDest(), I);
176 // Delete the old call site
177 I->eraseFromParent();
181 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
182 Users.insert(Users.end(), GV->use_begin(), GV->use_end());
183 EqPointers.push_back(GV);
184 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
186 Users.insert(Users.end(), CE->use_begin(), CE->use_end());
187 EqPointers.push_back(CE);
193 // Next, process all free calls...
195 std::vector<User*> Users(FreeFunc->use_begin(), FreeFunc->use_end());
196 std::vector<Value*> EqPointers; // Values equal to FreeFunc
198 while (!Users.empty()) {
199 User *U = Users.back();
202 if (Instruction *I = dyn_cast<Instruction>(U)) {
203 if (isa<InvokeInst>(I))
205 CallSite CS = CallSite::get(I);
206 if (CS.getInstruction() && !CS.arg_empty() &&
207 (CS.getCalledFunction() == FreeFunc ||
208 std::find(EqPointers.begin(), EqPointers.end(),
209 CS.getCalledValue()) != EqPointers.end())) {
211 // If no prototype was provided for free, we may need to cast the
212 // source pointer. This should be really uncommon, but it's necessary
213 // just in case we are dealing with weird code like this:
216 Value *Source = *CS.arg_begin();
217 if (!isa<PointerType>(Source->getType()))
218 Source = new IntToPtrInst(Source,
219 PointerType::getUnqual(Type::Int8Ty),
221 new FreeInst(Source, I);
223 // If the old instruction was an invoke, add an unconditional branch
224 // before the invoke, which will become the new terminator.
225 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
226 BranchInst::Create(II->getNormalDest(), I);
228 // Delete the old call site
229 if (I->getType() != Type::VoidTy)
230 I->replaceAllUsesWith(UndefValue::get(I->getType()));
231 I->eraseFromParent();
235 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
236 Users.insert(Users.end(), GV->use_begin(), GV->use_end());
237 EqPointers.push_back(GV);
238 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
240 Users.insert(Users.end(), CE->use_begin(), CE->use_end());
241 EqPointers.push_back(CE);