1 //===- RaiseAllocations.cpp - Convert %malloc & %free calls to insts ------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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 #include "llvm/Transforms/IPO.h"
16 #include "llvm/Module.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/iMemory.h"
19 #include "llvm/iTerminators.h"
20 #include "llvm/iOther.h"
21 #include "llvm/Pass.h"
22 #include "llvm/Support/CallSite.h"
23 #include "Support/Statistic.h"
27 Statistic<> NumRaised("raiseallocs", "Number of allocations raised");
29 // RaiseAllocations - Turn %malloc and %free calls into the appropriate
32 class RaiseAllocations : public Pass {
33 Function *MallocFunc; // Functions in the module we are processing
34 Function *FreeFunc; // Initialized by doPassInitializationVirt
36 RaiseAllocations() : MallocFunc(0), FreeFunc(0) {}
38 // doPassInitialization - For the raise allocations pass, this finds a
39 // declaration for malloc and free if they exist.
41 void doInitialization(Module &M);
43 // run - This method does the actual work of converting instructions over.
48 RegisterOpt<RaiseAllocations>
49 X("raiseallocs", "Raise allocations from calls to instructions");
50 } // end anonymous namespace
53 // createRaiseAllocationsPass - The interface to this file...
54 Pass *llvm::createRaiseAllocationsPass() {
55 return new RaiseAllocations();
59 // If the module has a symbol table, they might be referring to the malloc and
60 // free functions. If this is the case, grab the method pointers that the
63 // Lookup %malloc and %free in the symbol table, for later use. If they don't
64 // exist, or are not external, we do not worry about converting calls to that
65 // function into the appropriate instruction.
67 void RaiseAllocations::doInitialization(Module &M) {
68 const FunctionType *MallocType = // Get the type for malloc
69 FunctionType::get(PointerType::get(Type::SByteTy),
70 std::vector<const Type*>(1, Type::ULongTy), false);
72 const FunctionType *FreeType = // Get the type for free
73 FunctionType::get(Type::VoidTy,
74 std::vector<const Type*>(1, PointerType::get(Type::SByteTy)),
77 // Get Malloc and free prototypes if they exist!
78 MallocFunc = M.getFunction("malloc", MallocType);
79 FreeFunc = M.getFunction("free" , FreeType);
81 // Check to see if the prototype is wrong, giving us sbyte*(uint) * malloc
82 // This handles the common declaration of: 'void *malloc(unsigned);'
83 if (MallocFunc == 0) {
84 MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
85 std::vector<const Type*>(1, Type::UIntTy), false);
86 MallocFunc = M.getFunction("malloc", MallocType);
89 // Check to see if the prototype is missing, giving us sbyte*(...) * malloc
90 // This handles the common declaration of: 'void *malloc();'
91 if (MallocFunc == 0) {
92 MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
93 std::vector<const Type*>(), true);
94 MallocFunc = M.getFunction("malloc", MallocType);
97 // Check to see if the prototype was forgotten, giving us void (...) * free
98 // This handles the common forward declaration of: 'void free();'
100 FreeType = FunctionType::get(Type::VoidTy, std::vector<const Type*>(),true);
101 FreeFunc = M.getFunction("free", FreeType);
104 // One last try, check to see if we can find free as 'int (...)* free'. This
105 // handles the case where NOTHING was declared.
107 FreeType = FunctionType::get(Type::IntTy, std::vector<const Type*>(),true);
108 FreeFunc = M.getFunction("free", FreeType);
111 // Don't mess with locally defined versions of these functions...
112 if (MallocFunc && !MallocFunc->isExternal()) MallocFunc = 0;
113 if (FreeFunc && !FreeFunc->isExternal()) FreeFunc = 0;
116 // run - Transform calls into instructions...
118 bool RaiseAllocations::run(Module &M) {
119 // Find the malloc/free prototypes...
122 bool Changed = false;
124 // First, process all of the malloc calls...
126 std::vector<User*> Users(MallocFunc->use_begin(), MallocFunc->use_end());
127 while (!Users.empty()) {
128 if (Instruction *I = dyn_cast<Instruction>(Users.back())) {
129 CallSite CS = CallSite::get(I);
130 if (CS.getInstruction() && CS.getCalledFunction() == MallocFunc &&
131 CS.arg_begin() != CS.arg_end()) {
132 Value *Source = *CS.arg_begin();
134 // If no prototype was provided for malloc, we may need to cast the
136 if (Source->getType() != Type::UIntTy)
137 Source = new CastInst(Source, Type::UIntTy, "MallocAmtCast", I);
139 std::string Name(I->getName()); I->setName("");
140 MallocInst *MI = new MallocInst(Type::SByteTy, Source, Name, I);
141 I->replaceAllUsesWith(MI);
143 // If the old instruction was an invoke, add an unconditional branch
144 // before the invoke, which will become the new terminator.
145 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
146 new BranchInst(II->getNormalDest(), I);
148 // Delete the old call site
149 MI->getParent()->getInstList().erase(I);
159 // Next, process all free calls...
161 std::vector<User*> Users(FreeFunc->use_begin(), FreeFunc->use_end());
163 while (!Users.empty()) {
164 if (Instruction *I = dyn_cast<Instruction>(Users.back())) {
165 CallSite CS = CallSite::get(I);
166 if (CS.getInstruction() && CS.getCalledFunction() == FreeFunc &&
167 CS.arg_begin() != CS.arg_end()) {
169 // If no prototype was provided for free, we may need to cast the
170 // source pointer. This should be really uncommon, but it's necessary
171 // just in case we are dealing with wierd code like this:
174 Value *Source = *CS.arg_begin();
175 if (!isa<PointerType>(Source->getType()))
176 Source = new CastInst(Source, PointerType::get(Type::SByteTy),
178 new FreeInst(Source, I);
180 // If the old instruction was an invoke, add an unconditional branch
181 // before the invoke, which will become the new terminator.
182 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
183 new BranchInst(II->getNormalDest(), I);
185 // Delete the old call site
186 I->getParent()->getInstList().erase(I);