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creation functions in their public header file, unless they can help it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1816 91177308-0d34-0410-b5e6-96231b3b80d8
241 lines
8.7 KiB
C++
241 lines
8.7 KiB
C++
//===- ChangeAllocations.cpp - Modify %malloc & %free calls -----------------=//
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//
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// This file defines two passes that convert malloc and free instructions to
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// calls to and from %malloc & %free function calls. The LowerAllocations
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// transformation is a target dependant tranformation because it depends on the
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// size of data types and alignment constraints.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/ChangeAllocations.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Module.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/iMemory.h"
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#include "llvm/iOther.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/ConstantVals.h"
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#include "llvm/Pass.h"
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#include "TransformInternals.h"
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using std::vector;
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namespace {
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// LowerAllocations - Turn malloc and free instructions into %malloc and %free
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// calls.
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//
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class LowerAllocations : public BasicBlockPass {
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Method *MallocMeth; // Methods in the module we are processing
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Method *FreeMeth; // Initialized by doInitialization
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const TargetData &DataLayout;
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public:
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inline LowerAllocations(const TargetData &TD) : DataLayout(TD) {
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MallocMeth = FreeMeth = 0;
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}
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// doPassInitialization - For the lower allocations pass, this ensures that a
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// module contains a declaration for a malloc and a free function.
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//
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bool doInitialization(Module *M);
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// runOnBasicBlock - This method does the actual work of converting
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// instructions over, assuming that the pass has already been initialized.
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//
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bool runOnBasicBlock(BasicBlock *BB);
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};
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// RaiseAllocations - Turn %malloc and %free calls into the appropriate
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// instruction.
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//
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class RaiseAllocations : public BasicBlockPass {
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Method *MallocMeth; // Methods in the module we are processing
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Method *FreeMeth; // Initialized by doPassInitializationVirt
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public:
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inline RaiseAllocations() : MallocMeth(0), FreeMeth(0) {}
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// doPassInitialization - For the raise allocations pass, this finds a
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// declaration for malloc and free if they exist.
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//
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bool doInitialization(Module *M);
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// runOnBasicBlock - This method does the actual work of converting
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// instructions over, assuming that the pass has already been initialized.
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//
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bool runOnBasicBlock(BasicBlock *BB);
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};
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} // end anonymous namespace
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// doInitialization - For the lower allocations pass, this ensures that a
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// module contains a declaration for a malloc and a free function.
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//
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// This function is always successful.
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//
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bool LowerAllocations::doInitialization(Module *M) {
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bool Changed = false;
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const MethodType *MallocType =
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MethodType::get(PointerType::get(Type::SByteTy),
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vector<const Type*>(1, Type::UIntTy), false);
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SymbolTable *SymTab = M->getSymbolTableSure();
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// Check for a definition of malloc
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if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) {
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MallocMeth = cast<Method>(V); // Yup, got it
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} else { // Nope, add one
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M->getMethodList().push_back(MallocMeth = new Method(MallocType, false,
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"malloc"));
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Changed = true;
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}
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const MethodType *FreeType =
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MethodType::get(Type::VoidTy,
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vector<const Type*>(1, PointerType::get(Type::SByteTy)),
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false);
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// Check for a definition of free
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if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) {
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FreeMeth = cast<Method>(V); // Yup, got it
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} else { // Nope, add one
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M->getMethodList().push_back(FreeMeth = new Method(FreeType, false,"free"));
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Changed = true;
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}
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return Changed;
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}
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// runOnBasicBlock - This method does the actual work of converting
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// instructions over, assuming that the pass has already been initialized.
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//
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bool LowerAllocations::runOnBasicBlock(BasicBlock *BB) {
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bool Changed = false;
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assert(MallocMeth && FreeMeth && BB && "Pass not initialized!");
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// Loop over all of the instructions, looking for malloc or free instructions
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for (unsigned i = 0; i < BB->size(); ++i) {
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BasicBlock::InstListType &BBIL = BB->getInstList();
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if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) {
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BBIL.remove(BBIL.begin()+i); // remove the malloc instr...
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const Type *AllocTy =cast<PointerType>(MI->getType())->getElementType();
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// Get the number of bytes to be allocated for one element of the
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// requested type...
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unsigned Size = DataLayout.getTypeSize(AllocTy);
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// malloc(type) becomes sbyte *malloc(constint)
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Value *MallocArg = ConstantUInt::get(Type::UIntTy, Size);
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if (MI->getNumOperands() && Size == 1) {
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MallocArg = MI->getOperand(0); // Operand * 1 = Operand
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} else if (MI->getNumOperands()) {
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// Multiply it by the array size if neccesary...
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MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
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MallocArg);
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BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg));
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}
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// Create the call to Malloc...
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CallInst *MCall = new CallInst(MallocMeth,
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vector<Value*>(1, MallocArg));
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BBIL.insert(BBIL.begin()+i, MCall);
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// Create a cast instruction to convert to the right type...
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CastInst *MCast = new CastInst(MCall, MI->getType());
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BBIL.insert(BBIL.begin()+i+1, MCast);
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// Replace all uses of the old malloc inst with the cast inst
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MI->replaceAllUsesWith(MCast);
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delete MI; // Delete the malloc inst
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Changed = true;
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} else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) {
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BBIL.remove(BB->getInstList().begin()+i);
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// Cast the argument to free into a ubyte*...
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CastInst *MCast = new CastInst(FI->getOperand(0),
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PointerType::get(Type::UByteTy));
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BBIL.insert(BBIL.begin()+i, MCast);
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// Insert a call to the free function...
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CallInst *FCall = new CallInst(FreeMeth,
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vector<Value*>(1, MCast));
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BBIL.insert(BBIL.begin()+i+1, FCall);
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// Delete the old free instruction
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delete FI;
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Changed = true;
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}
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}
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return Changed;
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}
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bool RaiseAllocations::doInitialization(Module *M) {
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SymbolTable *ST = M->getSymbolTable();
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if (!ST) return false;
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// If the module has a symbol table, they might be referring to the malloc
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// and free functions. If this is the case, grab the method pointers that
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// the module is using.
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//
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// Lookup %malloc and %free in the symbol table, for later use. If they
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// don't exist, or are not external, we do not worry about converting calls
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// to that function into the appropriate instruction.
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//
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const PointerType *MallocType = // Get the type for malloc
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PointerType::get(MethodType::get(PointerType::get(Type::SByteTy),
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vector<const Type*>(1, Type::UIntTy), false));
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MallocMeth = cast_or_null<Method>(ST->lookup(MallocType, "malloc"));
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if (MallocMeth && !MallocMeth->isExternal())
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MallocMeth = 0; // Don't mess with locally defined versions of the fn
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const PointerType *FreeType = // Get the type for free
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PointerType::get(MethodType::get(Type::VoidTy,
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vector<const Type*>(1, PointerType::get(Type::SByteTy)), false));
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FreeMeth = cast_or_null<Method>(ST->lookup(FreeType, "free"));
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if (FreeMeth && !FreeMeth->isExternal())
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FreeMeth = 0; // Don't mess with locally defined versions of the fn
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return false;
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}
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// doOneCleanupPass - Do one pass over the input method, fixing stuff up.
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//
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bool RaiseAllocations::runOnBasicBlock(BasicBlock *BB) {
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bool Changed = false;
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BasicBlock::InstListType &BIL = BB->getInstList();
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for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
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Instruction *I = *BI;
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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if (CI->getCalledValue() == MallocMeth) { // Replace call to malloc?
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const Type *PtrSByte = PointerType::get(Type::SByteTy);
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MallocInst *MallocI = new MallocInst(PtrSByte, CI->getOperand(1),
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CI->getName());
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CI->setName("");
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ReplaceInstWithInst(BIL, BI, MallocI);
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Changed = true;
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continue; // Skip the ++BI
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} else if (CI->getCalledValue() == FreeMeth) { // Replace call to free?
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ReplaceInstWithInst(BIL, BI, new FreeInst(CI->getOperand(1)));
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Changed = true;
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continue; // Skip the ++BI
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}
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}
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++BI;
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}
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return Changed;
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}
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Pass *createLowerAllocationsPass(const TargetData &TD) {
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return new LowerAllocations(TD);
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}
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Pass *createRaiseAllocationsPass() {
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return new RaiseAllocations();
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}
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