1 //===- RaiseAllocations.cpp - Convert %malloc & %free calls to insts ------===//
3 // This file defines the RaiseAllocations pass which convert malloc and free
4 // calls to malloc and free instructions.
6 //===----------------------------------------------------------------------===//
8 #include "llvm/Transforms/ChangeAllocations.h"
9 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
10 #include "llvm/Module.h"
11 #include "llvm/Function.h"
12 #include "llvm/DerivedTypes.h"
13 #include "llvm/iMemory.h"
14 #include "llvm/iOther.h"
15 #include "llvm/Pass.h"
16 #include "Support/StatisticReporter.h"
18 static Statistic<> NumRaised("raiseallocs\t- Number of allocations raised");
22 // RaiseAllocations - Turn %malloc and %free calls into the appropriate
25 class RaiseAllocations : public BasicBlockPass {
26 Function *MallocFunc; // Functions in the module we are processing
27 Function *FreeFunc; // Initialized by doPassInitializationVirt
29 inline RaiseAllocations() : MallocFunc(0), FreeFunc(0) {}
31 const char *getPassName() const { return "Raise Allocations"; }
33 // doPassInitialization - For the raise allocations pass, this finds a
34 // declaration for malloc and free if they exist.
36 bool doInitialization(Module &M);
38 // runOnBasicBlock - This method does the actual work of converting
39 // instructions over, assuming that the pass has already been initialized.
41 bool runOnBasicBlock(BasicBlock &BB);
44 } // end anonymous namespace
47 // createRaiseAllocationsPass - The interface to this file...
48 Pass *createRaiseAllocationsPass() {
49 return new RaiseAllocations();
53 bool RaiseAllocations::doInitialization(Module &M) {
54 // If the module has a symbol table, they might be referring to the malloc
55 // and free functions. If this is the case, grab the method pointers that
56 // the module is using.
58 // Lookup %malloc and %free in the symbol table, for later use. If they
59 // don't exist, or are not external, we do not worry about converting calls
60 // to that function into the appropriate instruction.
62 const FunctionType *MallocType = // Get the type for malloc
63 FunctionType::get(PointerType::get(Type::SByteTy),
64 std::vector<const Type*>(1, Type::ULongTy), false);
66 const FunctionType *FreeType = // Get the type for free
67 FunctionType::get(Type::VoidTy,
68 std::vector<const Type*>(1, PointerType::get(Type::SByteTy)),
71 // Get Malloc and free prototypes if they exist!
72 MallocFunc = M.getFunction("malloc", MallocType);
73 FreeFunc = M.getFunction("free" , FreeType);
75 // Check to see if the prototype is wrong, giving us sbyte*(uint) * malloc
76 // This handles the common declaration of: 'void *malloc(unsigned);'
77 if (MallocFunc == 0) {
78 MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
79 std::vector<const Type*>(1, Type::UIntTy), false);
80 MallocFunc = M.getFunction("malloc", MallocType);
83 // Check to see if the prototype is missing, giving us sbyte*(...) * malloc
84 // This handles the common declaration of: 'void *malloc();'
85 if (MallocFunc == 0) {
86 MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
87 std::vector<const Type*>(), true);
88 MallocFunc = M.getFunction("malloc", MallocType);
91 // Check to see if the prototype was forgotten, giving us void (...) * free
92 // This handles the common forward declaration of: 'void free();'
94 FreeType = FunctionType::get(Type::VoidTy, std::vector<const Type*>(),true);
95 FreeFunc = M.getFunction("free", FreeType);
99 // Don't mess with locally defined versions of these functions...
100 if (MallocFunc && !MallocFunc->isExternal()) MallocFunc = 0;
101 if (FreeFunc && !FreeFunc->isExternal()) FreeFunc = 0;
105 // runOnBasicBlock - Process a basic block, fixing it up...
107 bool RaiseAllocations::runOnBasicBlock(BasicBlock &BB) {
108 bool Changed = false;
109 BasicBlock::InstListType &BIL = BB.getInstList();
111 for (BasicBlock::iterator BI = BB.begin(); BI != BB.end();) {
114 if (CallInst *CI = dyn_cast<CallInst>(I)) {
115 if (CI->getCalledValue() == MallocFunc) { // Replace call to malloc?
116 const Type *PtrSByte = PointerType::get(Type::SByteTy);
117 Value *Source = CI->getOperand(1);
119 // If no prototype was provided for malloc, we may need to cast the
121 if (Source->getType() != Type::UIntTy) {
122 CastInst *New = new CastInst(Source, Type::UIntTy, "MallocAmtCast");
123 BI = ++BIL.insert(BI, New);
127 MallocInst *MallocI = new MallocInst(PtrSByte, Source, CI->getName());
130 ReplaceInstWithInst(BIL, BI, MallocI);
133 continue; // Skip the ++BI
134 } else if (CI->getCalledValue() == FreeFunc) { // Replace call to free?
135 // If no prototype was provided for free, we may need to cast the
136 // source pointer. This should be really uncommon, but it's neccesary
137 // just in case we are dealing with wierd code like this:
140 Value *Source = CI->getOperand(1);
141 if (!isa<PointerType>(Source->getType())) {
142 CastInst *New = new CastInst(Source, PointerType::get(Type::SByteTy),
144 BI = ++BIL.insert(BI, New);
148 ReplaceInstWithInst(BIL, BI, new FreeInst(Source));
150 continue; // Skip the ++BI