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((intptr_t)&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);
52 char RaiseAllocations::ID = 0;
53 RegisterPass<RaiseAllocations>
54 X("raiseallocs", "Raise allocations from calls to instructions");
55 } // end anonymous namespace
58 // createRaiseAllocationsPass - The interface to this file...
59 ModulePass *llvm::createRaiseAllocationsPass() {
60 return new RaiseAllocations();
64 // If the module has a symbol table, they might be referring to the malloc and
65 // free functions. If this is the case, grab the method pointers that the
68 // Lookup @malloc and @free in the symbol table, for later use. If they don't
69 // exist, or are not external, we do not worry about converting calls to that
70 // function into the appropriate instruction.
72 void RaiseAllocations::doInitialization(Module &M) {
74 // Get Malloc and free prototypes if they exist!
75 MallocFunc = M.getFunction("malloc");
77 const FunctionType* TyWeHave = MallocFunc->getFunctionType();
79 // Get the expected prototype for malloc
80 const FunctionType *Malloc1Type =
81 FunctionType::get(PointerType::getUnqual(Type::Int8Ty),
82 std::vector<const Type*>(1, Type::Int64Ty), false);
84 // Chck to see if we got the expected malloc
85 if (TyWeHave != Malloc1Type) {
86 // Check to see if the prototype is wrong, giving us sbyte*(uint) * malloc
87 // This handles the common declaration of: 'void *malloc(unsigned);'
88 const FunctionType *Malloc2Type =
89 FunctionType::get(PointerType::getUnqual(Type::Int8Ty),
90 std::vector<const Type*>(1, Type::Int32Ty), false);
91 if (TyWeHave != Malloc2Type) {
92 // Check to see if the prototype is missing, giving us
93 // sbyte*(...) * malloc
94 // This handles the common declaration of: 'void *malloc();'
95 const FunctionType *Malloc3Type =
96 FunctionType::get(PointerType::getUnqual(Type::Int8Ty),
97 std::vector<const Type*>(), true);
98 if (TyWeHave != Malloc3Type)
105 FreeFunc = M.getFunction("free");
107 const FunctionType* TyWeHave = FreeFunc->getFunctionType();
109 // Get the expected prototype for void free(i8*)
110 const FunctionType *Free1Type = FunctionType::get(Type::VoidTy,
111 std::vector<const Type*>(1, PointerType::getUnqual(Type::Int8Ty)), false);
113 if (TyWeHave != Free1Type) {
114 // Check to see if the prototype was forgotten, giving us
116 // This handles the common forward declaration of: 'void free();'
117 const FunctionType* Free2Type = FunctionType::get(Type::VoidTy,
118 std::vector<const Type*>(),true);
120 if (TyWeHave != Free2Type) {
121 // One last try, check to see if we can find free as
122 // int (...)* free. This handles the case where NOTHING was declared.
123 const FunctionType* Free3Type = FunctionType::get(Type::Int32Ty,
124 std::vector<const Type*>(),true);
126 if (TyWeHave != Free3Type) {
134 // Don't mess with locally defined versions of these functions...
135 if (MallocFunc && !MallocFunc->isDeclaration()) MallocFunc = 0;
136 if (FreeFunc && !FreeFunc->isDeclaration()) FreeFunc = 0;
139 // run - Transform calls into instructions...
141 bool RaiseAllocations::runOnModule(Module &M) {
142 // Find the malloc/free prototypes...
145 bool Changed = false;
147 // First, process all of the malloc calls...
149 std::vector<User*> Users(MallocFunc->use_begin(), MallocFunc->use_end());
150 std::vector<Value*> EqPointers; // Values equal to MallocFunc
151 while (!Users.empty()) {
152 User *U = Users.back();
155 if (Instruction *I = dyn_cast<Instruction>(U)) {
156 CallSite CS = CallSite::get(I);
157 if (CS.getInstruction() && !CS.arg_empty() &&
158 (CS.getCalledFunction() == MallocFunc ||
159 std::find(EqPointers.begin(), EqPointers.end(),
160 CS.getCalledValue()) != EqPointers.end())) {
162 Value *Source = *CS.arg_begin();
164 // If no prototype was provided for malloc, we may need to cast the
166 if (Source->getType() != Type::Int32Ty)
168 CastInst::createIntegerCast(Source, Type::Int32Ty, false/*ZExt*/,
171 MallocInst *MI = new MallocInst(Type::Int8Ty, Source, "", I);
173 I->replaceAllUsesWith(MI);
175 // If the old instruction was an invoke, add an unconditional branch
176 // before the invoke, which will become the new terminator.
177 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
178 new BranchInst(II->getNormalDest(), I);
180 // Delete the old call site
181 MI->getParent()->getInstList().erase(I);
185 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
186 Users.insert(Users.end(), GV->use_begin(), GV->use_end());
187 EqPointers.push_back(GV);
188 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
190 Users.insert(Users.end(), CE->use_begin(), CE->use_end());
191 EqPointers.push_back(CE);
197 // Next, process all free calls...
199 std::vector<User*> Users(FreeFunc->use_begin(), FreeFunc->use_end());
200 std::vector<Value*> EqPointers; // Values equal to FreeFunc
202 while (!Users.empty()) {
203 User *U = Users.back();
206 if (Instruction *I = dyn_cast<Instruction>(U)) {
207 if (isa<InvokeInst>(I))
209 CallSite CS = CallSite::get(I);
210 if (CS.getInstruction() && !CS.arg_empty() &&
211 (CS.getCalledFunction() == FreeFunc ||
212 std::find(EqPointers.begin(), EqPointers.end(),
213 CS.getCalledValue()) != EqPointers.end())) {
215 // If no prototype was provided for free, we may need to cast the
216 // source pointer. This should be really uncommon, but it's necessary
217 // just in case we are dealing with weird code like this:
220 Value *Source = *CS.arg_begin();
221 if (!isa<PointerType>(Source->getType()))
222 Source = new IntToPtrInst(Source,
223 PointerType::getUnqual(Type::Int8Ty),
225 new FreeInst(Source, I);
227 // If the old instruction was an invoke, add an unconditional branch
228 // before the invoke, which will become the new terminator.
229 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
230 new BranchInst(II->getNormalDest(), I);
232 // Delete the old call site
233 if (I->getType() != Type::VoidTy)
234 I->replaceAllUsesWith(UndefValue::get(I->getType()));
235 I->eraseFromParent();
239 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
240 Users.insert(Users.end(), GV->use_begin(), GV->use_end());
241 EqPointers.push_back(GV);
242 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
244 Users.insert(Users.end(), CE->use_begin(), CE->use_end());
245 EqPointers.push_back(CE);